Inkjet recording method

Abstract

The present invention provides an inkjet recording method, which comprises: a step of preparing ink, wherein the ink contains water and particles containing a polymer P and a polymerizable monomer (M), the polymerizable monomer (M) containing a monomer (M-1) having a viscosity of 500 mPa·s or less at 25° C., and the content of the monomer (M-1) is 25% to 80% by mass relative to the total solid content of the particles; an imparting step of imparting the ink to a substrate by an inkjet method; and an irradiation step of irradiating the ink imparted to the substrate with active energy rays, wherein the time from the moment the ink lands on the substrate to the start of irradiation with the active energy rays is less than 1.00 second.

Description

Technical Field

[0001] The present disclosure relates to an inkjet recording method. Background Art

[0002] Conventionally, various studies have been conducted on inkjet inks and inkjet recording methods.

[0003] For example, Patent Document 1 discloses an inkjet ink composition containing water and particles as an inkjet ink composition that can form an image with excellent adhesion to a plastic substrate and has excellent dispersion stability, wherein the particles contain a chain polymer containing a specific structural unit and a hydrophilic group and contain a polymerizable group.

[0004] In addition, Patent Document 2 discloses an inkjet recording method having excellent curability, filling property, adhesion and ejection stability, which includes the following steps: a first step of ejecting droplets of a photocurable ink composition from a nozzle toward a recording medium and causing them to land to form an image, wherein the photocurable ink composition contains a solvent, a polymerizable compound and a photopolymerization initiator, and the polymerizable compound is particles dispersed in the solvent; a second step of evaporating the solvent contained in the photocurable ink composition constituting the image; and a third step of irradiating the image after the second step with light, wherein, when irradiation starts in the third step, the content of the polymerizable compound contained in the photocurable ink composition constituting the image after the second step is 20 to 90% by mass relative to the total mass of the ink composition.

[0005] In addition, Patent Document 3 discloses an active energy ray-curable composition containing the following components as an active energy ray-curable composition and an active energy ray-curable ink composition that cures with high sensitivity even when irradiated with low-output active energy rays, has little bleed-out of surfactant, and has excellent stability over time: (A) a polymerizable compound having an ethylenically unsaturated bond and being substantially insoluble in water; (B) a surfactant having one or more groups selected from the group consisting of an acrylate group, a methacrylate group, an acrylamide group, and a methacrylamide group; (C) a polymerization initiator; and (D) water. Patent Document 3 also discloses an inkjet recording method using the active energy ray-curable composition.

[0006] In addition, in Patent Document 4, as an inkjet recording method having excellent ejection stability, resistance to secondary color bleed-out, resistance to flocculation and feathering, and excellent layering, there is disclosed an inkjet recording method in which inkjet ink is ejected from an inkjet recording head and recorded on a recording medium. The method is characterized in that the inkjet ink contains at least a colorant, a photoreactive resin and water, and after the inkjet ink is ejected on the recording medium, the volatile components contained in the inkjet ink are concentrated by drying means or by penetration into the recording medium before the step of irradiating active energy rays.

[0007] Previous technical literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent No. 6584677

[0010] Patent Document 2: Japanese Patent No. 6047904

[0011] Patent Document 3: Japanese Patent Application Publication No. 2011-208088

[0012] Patent Document 4: Japanese Patent Application Publication No. 2008-194827 Summary of the invention

[0013] Technical issues to be solved by the invention

[0014] However, in an inkjet recording method in which an active energy ray-curable inkjet ink containing a polymerizable monomer is landed on a substrate and the landed inkjet ink is cured by irradiating active energy rays to obtain an image, the time from the landing of the ink to the start of active energy ray irradiation is sometimes shortened (for example, sometimes set to less than 1.00 seconds) for the purpose of improving the image quality.

[0015] However, the inventors of the present invention have discovered through research that, in an inkjet recording method using an inkjet ink containing water and particles including a polymer and a polymerizable monomer, even if the time from ink landing to the start of active energy ray irradiation is shortened, the image quality is not improved, and the abrasion resistance of the image is sometimes reduced.

[0016] The present disclosure has been made in view of the above circumstances.

[0017] An object of one aspect of the present disclosure is to provide an inkjet recording method capable of recording an image having excellent image quality and abrasion resistance.

[0018] Means for solving technical problems

[0019] Specific means for solving the above-mentioned problems include the following aspects.

[0020] <1> An inkjet recording method comprising:

[0021] A step of preparing an ink, wherein the ink contains water and particles containing a polymer P and a polymerizable monomer M, wherein the polymerizable monomer M contains a monomer (M-1) having a viscosity of 500 mPa·s or less at 25° C., and the content of the monomer (M-1) is 25% to 80% by mass relative to the total solid content of the particles;

[0022] an imparting step of imparting the ink to a substrate by an inkjet method; and

[0023] an irradiation step of irradiating the ink applied on the substrate with active energy rays,

[0024] The time from the time when the ink lands on the substrate to the start of irradiation with the active energy ray is 1.00 second or less.

[0025] <2> According to the <1> The inkjet recording method, wherein:

[0026] The monomer (M-1) includes a monomer (M1A) having a viscosity at 25° C. of 150 mPa·s or less.

[0027] <3> According to the <1> or <2> The inkjet recording method, wherein:

[0028] The total solid content of the particles in the ink at the time when the irradiation with the active energy rays starts is 3 mass % or more and less than 20 mass % based on the total amount of the ink at the time when the irradiation with the active energy rays starts.

[0029] <4> According to the <1> ~ <3> The inkjet recording method according to any one of the preceding claims, wherein:

[0030] In the applying step, the temperature of the surface of the substrate on the ink landing side is 30°C to 70°C.

[0031] <5> According to the <1> ~ <4> The inkjet recording method according to any one of the preceding claims,

[0032] The inkjet recording method satisfies at least one of the following:

[0033] Prior to the imparting step, a preheating step of heating the substrate is included; and

[0034] In the applying step, the substrate is heated and the ink is applied.

[0035] <6> According to the <1> ~ <5> The inkjet recording method according to any one of the preceding claims, wherein:

[0036] In the irradiation step, the irradiation energy of the active energy line is 300 mJ / cm 2 above,

[0037] The content of the liquid component in the ink after the irradiation with the active energy ray is 10% by mass or more relative to the content of the liquid component in the ink before the irradiation with the active energy ray.

[0038] <7> According to the <1> ~ <6> The inkjet recording method according to any one of the preceding claims, wherein:

[0039] The method further includes a drying step of heating and drying the ink irradiated with the active energy rays.

[0040] <8> According to the <7> The inkjet recording method, wherein:

[0041] In the drying step, the content of the liquid component in the ink after heat drying is 2.0% by mass to 50% by mass relative to the content of the liquid component in the ink before heat drying.

[0042] Effects of the Invention

[0043] According to one aspect of the present disclosure, there is provided an inkjet recording method capable of recording an image having excellent image quality and abrasion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The figure shows a character image used for evaluating the image quality in the example. DETAILED DESCRIPTION

[0045] In the present disclosure, a numerical range expressed by “to” means a range including the numerical values ​​described before and after “to” as the minimum value and the maximum value, respectively.

[0046] In the present disclosure, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition refers to the total amount of the plurality of substances present in the composition unless otherwise specified.

[0047] In the numerical ranges described in sections in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced by the upper limit value or the lower limit value of the numerical range described in another section, and may also be replaced by the value shown in the Examples.

[0048] In the present disclosure, the term "process" refers not only to an independent process but also to a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

[0049] In the present disclosure, "*" in a chemical formula indicates a bonding position.

[0050] In the present disclosure, the concept of “image” includes not only pattern images (eg, text, symbols, or graphics) but also solid images.

[0051] In the present disclosure, “light” is a concept including active energy rays such as gamma rays, beta rays, electron beams, ultraviolet rays, and visible rays.

[0052] In the present disclosure, irradiation with active energy rays is sometimes referred to as "exposure".

[0053] In this disclosure, ultraviolet rays are sometimes referred to as "UV (Ultra Violet) light".

[0054] In this disclosure, light generated by an LED (Light Emitting Diode) light source is sometimes referred to as “LED light”.

[0055] In the present disclosure, “(meth)acrylic acid” is a concept including both acrylic acid and methacrylic acid, “(meth)acrylate” is a concept including both acrylate and methacrylate, and “(meth)acryloyl” is a concept including both acryloyl and methacryloyl.

[0056] [Inkjet recording method]

[0057] The inkjet recording method in the present disclosure (hereinafter, also simply referred to as “recording method”) includes:

[0058] A step of preparing an ink, wherein the ink contains water and particles containing a polymer P and a polymerizable monomer M (hereinafter also referred to as "specific particles"), wherein the polymerizable monomer M contains a monomer (M-1) having a viscosity of 500 mPa·s or less at 25° C., and the content of the monomer (M-1) is 25% by mass to 80% by mass relative to the total solid content of the specific particles;

[0059] a step of applying ink to the substrate by inkjet method; and

[0060] In the irradiation step, the ink applied on the substrate is irradiated with active energy rays.

[0061] The time from the moment when the ink landed on the substrate to the start of the active energy ray irradiation was 1.00 second or less.

[0062] As described above, the present inventors have discovered through research that in an inkjet recording method in which an inkjet ink containing water and particles containing a polymer and a polymerizable monomer is deposited on a substrate and an image is obtained by curing the deposited inkjet ink by irradiating active energy rays, when the time from the landing of the ink to the start of exposure is shortened (specifically, when it is set to less than 1.00 seconds), the image quality is not improved, and the abrasion resistance of the image is sometimes reduced.

[0063] The reason for this phenomenon is considered to be as follows.

[0064] It is believed that in order to ensure the image quality and wear resistance, it is important that the polymerizable monomer seeps out from the particles to a certain extent at the start of exposure, and the polymerizable monomer seeps out from the particles during exposure, thereby performing solidification between the particles (i.e., the connection between the particles). It is believed that by performing solidification between the particles, excellent film (image) strength is obtained, and the wear resistance of the image is improved. In addition, it is believed that by performing solidification between the particles, the ink on the substrate can be thickened, thereby improving the image quality.

[0065] However, when the time from ink landing to exposure start is less than 1.00 seconds, the polymerizable monomer may not ooze out sufficiently from the particles in the ink at the start of exposure. As a result, the solidification mainly proceeds within the particles, and the solidification between the particles (i.e., the connection between the particles) is insufficient, and as a result, the image quality and abrasion resistance may be reduced.

[0066] With regard to the above-mentioned problems, according to the recording method of the present disclosure, an image having excellent image quality and abrasion resistance can be obtained even though the time from ink landing to the start of exposure is 1.00 second or less.

[0067] The reason why this effect is achieved is considered to be as follows.

[0068] The ink used in the recording method of the present disclosure contains specific particles including a polymer P and a polymerizable monomer M. The polymerizable monomer M includes a monomer (M-1) having a viscosity of 500 mPa·s or less at 25° C. The content of the monomer (M-1) is 25% to 80% by mass relative to the total solid content of the specific particles.

[0069] It is believed that since the ink contains a relatively large amount (i.e., 25% by mass or more) of low-viscosity (i.e., 500 mPa·s or less) monomer (M-1) in the particles, the monomer (M-1) effectively oozes out of the particles after the ink lands, thereby allowing solidification between the particles (i.e., bonding between the particles) to proceed sufficiently. As a result, it is believed that an image with excellent image quality and abrasion resistance can be obtained even though the time from the landing of the ink to the start of exposure is less than 1.00 second.

[0070] Furthermore, a content of the monomer (M-1) of 80% by mass or less contributes to the ejection properties of the ink from an inkjet head, and the effect of the ejection properties also contributes to image quality and abrasion resistance.

[0071] In the present disclosure, the total solid content of specific particles refers to the total amount after removing the solvent (ie, water and organic solvent) from the specific particles. When the specific particles do not contain a solvent, the total solid content of the specific particles is consistent with the total amount of the specific particles.

[0072] As described above, in the recording method of the present disclosure, the time from the landing of the ink to the start of exposure is 1.00 second or less.

[0073] In the recording method disclosed herein, not only is the content of the monomer (M-1) 25% by mass or more relative to the total solid content of the specific particles, but the time from the landing of the ink to the start of exposure is 1.00 seconds or less, which itself contributes to the improvement of the image quality. This is believed to be because the ink dropped on the substrate is exposed to a certain degree of speed (i.e., within 1.00 seconds), which can suppress the movement of the ink landed on the substrate.

[0074] Hereinafter, each process that may be included in the recording method of the present disclosure will be described.

[0075] <Ink Preparation Process>

[0076] This step is a step of preparing ink used in the recording method of the present disclosure.

[0077] The ink contains water and particles including a polymer P and a polymerizable monomer M (i.e., specific particles), wherein the polymerizable monomer M includes a monomer (M-1) having a viscosity of 500 mPa·s or less at 25°C, and the content of the monomer (M-1) is 25% to 80% by mass relative to the total solid content of the specific particles.

[0078] This step may be a step of manufacturing the ink or a step of simply preparing the ink manufactured in advance.

[0079] Preferred embodiments of the ink used in the recording method of the present disclosure will be described later.

[0080] <Assignment process>

[0081] The applying step is a step of applying the ink onto the substrate by an inkjet method.

[0082] (Base material)

[0083] The substrate used in the recording method of the present disclosure is not particularly limited and may be either an impermeable substrate or a permeable substrate, but is preferably an impermeable substrate.

[0084] Here, the non-permeable substrate refers to a substrate having a water absorption rate (unit: mass %, measurement time: 24 hours) of less than 10 in ASTM D570 of the ASTM test method.

[0085] The water absorption of the impermeable substrate is preferably 5 or less.

[0086] Examples of the impermeable substrate include:

[0087] Paper laminated with plastic (e.g. polyethylene, polypropylene, polystyrene, etc.),

[0088] Metal plates (e.g., aluminum, zinc, copper, etc.),

[0089] Plastic films (e.g., films of polyvinyl chloride (PVC: Polyvinyl Chloride) resin, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate (PET: Polyethylene Terephthalate), polyethylene (PE: Polyethylene), polystyrene (PS: Polystyrene), polypropylene (PP: Polypropylene), polycarbonate (PC: Polycarbonate), polyvinyl acetal, acrylic resin, etc.),

[0090] Paper laminated or vapor-deposited with the above metals,

[0091] Plastic films laminated or vapor-deposited with the above metals,

[0092] Leather, etc.

[0093] Examples of leather include natural leather (also referred to as "genuine leather") and synthetic leather (eg, PVC (polyvinyl chloride) leather, PU (polyurethane) leather). For leather, for example, see paragraphs 0163 to 0165 of Japanese Patent Application Laid-Open No. 2009-058750.

[0094] For example, when a film is formed on a leather (eg, a seat cushion for a vehicle, a bag, a shoe, a wallet, etc.) or a plastic film which is an impermeable substrate, the formed film is required to have excellent abrasion resistance and adhesion.

[0095] Furthermore, when a film is formed on a substrate other than leather or a plastic film, the formed film may also be required to have excellent abrasion resistance and adhesion.

[0096] According to the film formation method of the present disclosure, such a requirement can be met.

[0097] From the viewpoint of increasing the surface energy, the substrate may be surface treated.

[0098] Examples of the surface treatment include corona treatment, plasma treatment, flame treatment, heat treatment, abrasion treatment, light irradiation treatment (UV treatment), and flame treatment, but the surface treatment is not limited to these treatments.

[0099] (Ink application conditions, etc.)

[0100] Application of ink by the inkjet method can be performed by ejecting ink from an inkjet head of a known inkjet recording device.

[0101] As the inkjet head, a piezoelectric inkjet head is preferable.

[0102] The resolution of the inkjet head is preferably 300 dpi or more, more preferably 600 dpi or more, and even more preferably 800 dpi or more.

[0103] Here, dpi (dot per inch) means the number of dots per 2.54 cm (1 inch).

[0104] The droplet amount of ink ejected from the inkjet head (droplet amount per dot) is preferably 1 pL (picoliter) to 100 pL, more preferably 3 pL to 80 pL, and even more preferably 3 pL to 50 pL.

[0105] (Substrate temperature, etc.)

[0106] In the application step, the temperature of the surface of the substrate on the ink landing side is preferably 20°C to 80°C, more preferably 25°C to 75°C, further preferably 30°C to 70°C, further preferably 40°C to 70°C.

[0107] When the temperature of the surface of the substrate on the ink landing side is 20° C. to 80° C., the image quality and abrasion resistance are further improved. This is considered to be because the effect of the monomer (M-1) bleeding out from the specific particles is more easily obtained.

[0108] (Heating of substrate)

[0109] The recording method of the present disclosure preferably satisfies at least one of the following: including a preheating step of heating the substrate before the imparting step; and performing heating of the substrate and imparting of ink in the imparting step.

[0110] This further improves the image quality and abrasion resistance of the image. This is considered to be because the effect of the monomer (M-1) seeping out from the specific particles is more easily obtained.

[0111] In addition, when the recording method of the present disclosure satisfies at least one of the above conditions, it is easy to adjust the temperature of the surface of the substrate to the above preferred temperature.

[0112] In each step of heating in the preheating step and the heating in the imparting step, the heating device used to heat the substrate is not particularly limited, and examples thereof include: a heating drum, hot air, an infrared lamp, an infrared LED, an infrared heater, a hot oven, a heating plate, an infrared laser, an infrared dryer, etc.

[0113] <Irradiation process>

[0114] The irradiation step is a step of irradiating the ink applied on the substrate with active energy rays (in other words, a step of exposing the ink applied on the substrate to light).

[0115] By irradiation with active energy rays in this step (i.e., exposure), the polymerizable monomer M in the ink is polymerized, the ink is cured, and an image is obtained. More specifically, as described above, after the ink is deposited, the monomer (M-1) effectively oozes out from the specific particles, thereby sufficiently curing between the specific particles (i.e., the connection between the specific particles), and as a result, an image with excellent image quality and abrasion resistance is obtained.

[0116] Examples of active energy rays include ultraviolet rays (UV light), visible rays, and electron beams. Among them, UV light is preferred.

[0117] The irradiation of the ink applied on the substrate with the active energy rays may be performed in a state where the substrate and the ink applied on the substrate are heated.

[0118] As the irradiation conditions and basic irradiation method of the active energy rays, the irradiation conditions and irradiation method disclosed in paragraph 0023 of Japanese Patent Application Laid-Open No. 60-132767 and Japanese Patent Application Laid-Open No. 2014-132081 can be applied.

[0119] In the recording method of the present disclosure, as described above, the time from the moment when the ink lands to the start of the active energy ray irradiation is short (ie, 1.00 second or less).

[0120] The ink application and active energy ray irradiation of this method are preferably performed using an inkjet recording apparatus including a unit including an active energy ray irradiation inkjet head and an active energy ray source disposed near the inkjet head.

[0121] According to this unit, after the ink is ejected from the inkjet head of the unit and lands on the substrate, the active energy ray can be irradiated from the active energy ray source of the unit at a rapid timing of 1.00 second or less after the landing.

[0122] Examples of light sources for active energy ray irradiation include mercury lamps, metal halide lamps, high-pressure mercury lamps, medium-pressure mercury lamps, low-pressure mercury lamps, ultraviolet fluorescent lamps, gas lasers, solid-state lasers, LEDs (light emitting diodes), and LDs (laser diodes).

[0123] Among them, as the light source for active energy ray irradiation, a metal halide lamp, a high pressure mercury lamp, a medium pressure mercury lamp, a low pressure mercury lamp or an ultraviolet LED (hereinafter also referred to as UV-LED) as a light source for ultraviolet ray irradiation is preferred.

[0124] The peak wavelength of ultraviolet rays is, for example, preferably from 200 nm to 405 nm, more preferably from 220 nm to 400 nm, and further preferably from 340 nm to 400 nm.

[0125] The peak wavelength of light from the LED light source (LED light) is preferably 200 nm to 600 nm, more preferably 300 nm to 450 nm, further preferably 320 nm to 420 nm, further preferably 340 nm to 405 nm, further preferably 355 nm, 365 nm, 385 nm, 395 nm or 405 nm.

[0126] As the UV-LED, for example, there can be mentioned UV-LEDs manufactured by Nichia Chemical Corporation, which have a main emission spectrum with wavelengths of 365 nm and 420 nm.

[0127] In addition, there can be mentioned UV-LEDs described in US Pat. No. 6,084,250 that can emit active rays centered between 300 nm and 370 nm.

[0128] In addition, by combining a plurality of UV-LEDs, it is possible to irradiate ultraviolet rays in different wavelength ranges.

[0129] The irradiation energy (i.e., exposure amount) of the active energy ray is preferably 20 mJ / cm 2 More preferably, 100 mJ / cm 2 More preferably, 300 mJ / cm 2 More than 500 mJ / cm 2 Above, most preferably 900mJ / cm 2 above.

[0130] There is no particular upper limit on the exposure amount, and the upper limit may be 5 J / cm 2 , or 1,500mJ / cm 2 .

[0131] The maximum illumination of LED on the substrate is preferably 10mW / cm 2 ~8,000mW / cm 2 , more preferably 20 mW / cm 2 ~5,000mW / cm 2 , further preferably 30mW / cm 2 ~3000mW / cm 2 , further preferably 50mW / cm 2 ~1000mW / cm 2 .

[0132] The irradiation time of the active energy ray is preferably 0.01 to 120 seconds, more preferably 0.1 to 90 seconds.

[0133] (Time from ink landing to exposure start)

[0134] In the recording method of the present disclosure, the time from the landing of the ink to the start of exposure (ie, the time from the moment when the ink lands on the substrate to the start of irradiation with active energy rays) is 1.00 second or less.

[0135] As described above, a time from ink landing to the start of exposure of 1.00 second or less contributes to improved image quality.

[0136] The lower limit of the time from ink landing to the start of exposure is not particularly limited, and examples thereof include 0.01 seconds, 0.05 seconds, and 0.10 seconds.

[0137] (Total solid content of specific particles in ink at the time of exposure start)

[0138] In the recording method of the present disclosure, the total solid content of specific particles in the ink at the time when irradiation with active energy rays starts (also referred to as "exposure start time" in the present disclosure) is preferably 3 mass % or more and less than 20 mass % relative to the total amount of ink.

[0139] The total solid content of the specific particles in the ink at the start of exposure is less than 20% by mass, which means that the ink applied to the substrate is in an insufficiently dry state (specifically, the state in which the liquid component contains water and / or a water-soluble organic solvent exceeding 80% by mass), and the active energy ray is irradiated to the insufficiently dry ink. According to the active energy ray irradiation of this mode, the exudation of the monomer (M-1) and the curing between the specific particles can be more effectively achieved, so that the image quality and abrasion resistance are further improved.

[0140] The total solid content of the specific particles in the ink at the start of exposure is preferably 4% by mass to 19% by mass, and more preferably 5% by mass to 15% by mass.

[0141] The total solid content of specific particles in the ink at the start of exposure can be adjusted by, for example

[0142] The total solid content of specific particles in the ink before being ejected from the inkjet head,

[0143] The time from ink landing to exposure start,

[0144] The temperature of the surface of the substrate is adjusted.

[0145] The total solid content of specific particles in the ink at the start of exposure can be determined as follows.

[0146] That is, the total solid content (mass %) of the specific particles in the ink before ejection is regarded as the total solid content (mass %) of the specific particles in the ink at the time of landing on the substrate.

[0147] The total solid content (mass %) of specific particles in the ink at the time of landing on the substrate,

[0148] The drying speed of the ink (vol% / s) obtained using a contact angle meter, and

[0149] The total solid content of specific particles in the ink at the start of exposure was determined from the time from ink landing to the start of exposure.

[0150] The drying speed (vol% / s) of the ink was measured using a contact angle meter.

[0151] For example, the drying speed (vol% / s) of the ink when the volume of the ink droplet is 10 pL (droplet radius 13.4 μm) is obtained as follows (1) to (4). As the apparatus, an FTA-1000 contact angle meter and a warm water circulation temperature control stage manufactured by FTA Corporation are used.

[0152] (1) The temperature control stage was heated to a predetermined temperature, and the time change of the droplet volume of each of 0.5 μL (droplet radius 492 μm) and 1 μL (droplet radius 620 μm) ink droplets was measured until 20 seconds. The time change of the droplet volume was obtained based on the time change of the contact angle.

[0153] The drying rate (vol% / s) at each droplet amount was calculated based on the slope of the obtained linear relationship (time vs. droplet volume).

[0154] (2) Based on the obtained drying rate (vol% / s) and droplet radius (492 μm or 620 μm), DGAS (Cv-Ca) and L were calculated by the following formula (A).

[0155] J=DGAS(Cv-Ca)(1 / R+1 / L)…Formula (A)

[0156] [In formula (A), J represents the drying rate (vol% / s), DGAS represents the diffusion coefficient of the gas phase, Cv represents the vapor concentration on the droplet surface, Ca represents the vapor concentration of the atmosphere, R represents the droplet radius, and L represents the thickness of the vapor diffusion layer]

[0157] (Source: "Applications and Materials of Inkjet Printers 2", CMC Publishing 2007)

[0158] (3) DGAS (Cv-Ca) and L obtained in (2) above are substituted into the formula (A), and J (drying speed) of an ink droplet of 10 pL (droplet radius 13.4 μm) is calculated using the obtained mathematical formula.

[0159] (4) Using J (drying speed) obtained in (3) above, the amount of evaporation of the liquid component (i.e., water and water-soluble organic solvent) from the time when the ink lands to the start of exposure (i.e., a value of 1.00 seconds or less) is calculated. Based on the obtained evaporation amount and the total solid content of the specific particles in the ink at the time of landing on the substrate (i.e., the total solid content of the specific particles in the ink before ejection), the total solid content of the specific particles in the ink at the start of exposure is calculated.

[0160] When the volume of the ink droplet is a value other than 10 pL, the total solid content of the specific particles in the ink at the start of exposure can be calculated in the same manner as in the case of 10 pL.

[0161] From the viewpoint of an inkjet recording method capable of recording an image with higher image quality and abrasion resistance, in the irradiation step, the irradiation condition of the active energy ray is such that the irradiation energy of the active energy ray is 300 mJ / cm 2 As described above, the content of the liquid component in the ink after irradiation with active energy rays is preferably 10 mass % or more, more preferably 20 mass % or more and 70 mass % or less, and further preferably 25 mass % or more and 60 mass % or less relative to the content of the liquid component in the ink before irradiation with active energy rays.

[0162] Hereinafter, in the irradiation step, the content of the liquid component in the ink after irradiation with the active energy ray relative to the content of the liquid component in the ink before irradiation with the active energy ray is also referred to as "liquid component residual amount in the irradiation step".

[0163] The content of the liquid component in the ink before irradiation with the active energy ray and the content of the liquid component in the ink after irradiation with the active energy ray are respectively obtained, and the amount of the liquid component remaining in the irradiation step is obtained based on the obtained values.

[0164] The content of the liquid component in the ink before irradiation with the active energy ray was determined as follows.

[0165] The sample obtained by performing the above-mentioned steps of preparing the ink to the above-mentioned step of imparting in the actual inkjet recording method is used as a measurement sample of the content of the liquid component in the ink before irradiation with active energy rays (hereinafter referred to as a sample before irradiation). It is assumed that the ink is imparted in the imparting step to form a square solid image of 4 cm×4 cm, and no irradiation with active energy rays is performed. Even if heating is performed when the ink is imparted in the actual inkjet recording method, the substrate is not heated when the ink is imparted when preparing the measurement sample.

[0166] Then, the content of the liquid component in the ink before irradiation with active energy rays was determined by the same method as the content of the liquid component in the ink (ie, image) before heat drying described later, except that the sample before irradiation was used instead of the image recorded material 1 described later.

[0167] Specifically, the mass content of the water-soluble organic solvent in the ink of the sample before irradiation is quantified by gas chromatography (GC) using the same method as the content of the liquid component in the ink (i.e., the image) before heat drying described later, and the mass content of water in the ink of the sample before irradiation is quantified by Karl Fischer titration.

[0168] The value obtained by adding up the content mass of the water-soluble organic solvent and the content mass of water obtained above is used as the content mass of the liquid component in the ink before irradiation with the active energy ray.

[0169] In addition, the content of the liquid component in the ink after irradiation with the active energy rays was determined as follows.

[0170] The sample obtained by performing the steps from the ink preparation step to the irradiation step in the actual inkjet recording method is used as a sample for measuring the content of the liquid component in the ink after irradiation with active energy rays (hereinafter referred to as a sample after irradiation). It is assumed that, similar to the preparation of the sample before irradiation, the image formed in the imparting step is a solid image of a square of 4 cm×4 cm, and no active energy rays are irradiated except in the irradiation step. Even if heating is performed when imparting ink in the actual inkjet recording method, the substrate is not heated when imparting ink in the sample for measurement.

[0171] Then, the content of the liquid component in the ink after irradiation with active energy rays is determined by the same method as the content of the liquid component in the ink (ie, image) before heat drying described later, except that the irradiated sample is used instead of the image recorded material 1 described later.

[0172] Specifically, the mass content of the water-soluble organic solvent in the ink of the sample after irradiation is quantified by gas chromatography (GC) using the same method as the content of the liquid component in the ink (i.e., the image) before heat drying described later, and the mass content of water in the ink of the sample after irradiation is quantified by Karl Fischer titration.

[0173] The value obtained by adding up the content mass of the water-soluble organic solvent and the content mass of water obtained above is used as the content mass of the liquid component in the ink after irradiation with the active energy ray.

[0174] In the examples described below, the substrate is changed to an OPP (oriented polypropylene) substrate to prepare pre-irradiation samples and post-irradiation samples, and the amount of liquid component remaining in the irradiation step is measured using the prepared pre-irradiation samples and post-irradiation samples and the OPP substrate as a blank.

[0175] <Drying process>

[0176] The recording method of the present disclosure preferably further includes a drying step of heating and drying the ink (ie, the image) after being irradiated with the active energy rays.

[0177] This further improves the abrasion resistance of the image and further suppresses the blocking of the image.

[0178] The heating device for heating the ink is not particularly limited, and examples thereof include a heating drum, hot air, an infrared lamp, an infrared LED, an infrared heater, a hot oven, a hot plate, an infrared laser, and an infrared dryer.

[0179] The heating temperature for heat drying is preferably 40°C or higher, more preferably 40°C to 200°C, further preferably 40°C to 100°C, further preferably 40°C to 80°C, further preferably 45°C to 70°C.

[0180] The heating temperature refers to the temperature of the ink on the substrate, and can be measured with a temperature measuring instrument using an infrared thermal imaging device H2640 (manufactured by Japan Avionics Co., Ltd.).

[0181] The heating time can be appropriately set in consideration of the heating temperature, ink composition, printing speed, etc. The heating time is preferably 5 seconds or longer, more preferably 5 seconds to 20 minutes, more preferably 10 seconds to 10 minutes, and further preferably 20 seconds to 5 minutes.

[0182] (Content of liquid components in the ink after heating and drying)

[0183] In the drying process, the content of the liquid component in the ink after heat drying relative to the content of the liquid component in the ink before heat drying (hereinafter also referred to as "the residual amount of liquid component in the drying process") is preferably 50 mass % or less, more preferably 2.0 mass % to 50 mass %, and further preferably 2.0 mass % to 40 mass %.

[0184] When the amount of the liquid component remaining in the drying step is 50% by mass or less, the image quality and abrasion resistance of the image are further improved.

[0185] When the amount of the liquid component remaining in the drying step is 2.0% by mass or more, the adhesion of the image to the substrate is further improved.

[0186] The amount of the liquid component remaining in the drying process can be adjusted by adjusting the heating conditions (for example, heating temperature and heating time) in the drying process.

[0187] Here, the liquid component refers to water and a water-soluble organic solvent.

[0188] The content of the liquid component in the ink before heat drying refers to the mass of the liquid component in the ink before heat drying (that is, the total mass of water and the water-soluble organic solvent).

[0189] The content of the liquid component in the heat-dried ink refers to the mass of the liquid component in the heat-dried ink (that is, the total mass of water and the water-soluble organic solvent).

[0190] The ink before heating and drying and the ink after heating and drying are both inks after being irradiated with active energy rays, and therefore both correspond to the "image" in the present disclosure. Therefore, in the present disclosure, the ink before heating and drying and the ink after heating and drying can also be referred to as the image before heating and drying and the image after heating and drying, respectively.

[0191] The content of the liquid component in the ink before heat drying and the content of the liquid component in the ink after heat drying are calculated as follows, and the residual amount of the liquid component in the drying process is calculated based on the obtained values ​​(that is, the content of the liquid component in the ink after heat drying relative to the content of the liquid component in the ink before heat drying (mass %)).

[0192] The content (ie, contained mass) of the liquid component in the ink (ie, image) before heat drying was measured as follows using an image-bearing substrate after exposure and before heat drying (hereinafter referred to as "image recorded material 1").

[0193] First, a mixed solution of methanol / tetrahydrofuran (THF) = 1 / 1 (volume ratio) was used to extract the water-soluble organic solvent in the image of the image recorded material 1 at 25°C for 24 hours. The amount of the extracted water-soluble organic solvent was quantified by gas chromatography (GC) using the obtained extract.

[0194] Next, the amount of water contained in the image on the image recorded material 1 was quantified by Karl Fischer titration.

[0195] The value obtained by adding up the mass content of the water-soluble organic solvent and the mass content of water obtained above is used as the mass content of the liquid component in the ink (that is, the image) before heat drying.

[0196] An example of a method for measuring the content of a water-soluble organic solvent using the image recorded material 1 is shown below. This example is an example in which the water-soluble organic solvent is propylene glycol (PG).

[0197] Three rectangular test pieces of 15 mm×8 mm were collected from the image recorded material 1 .

[0198] As solvent A, a mixed solution of methanol / tetrahydrofuran (THF) = 1 / 1 (volume ratio) was prepared.

[0199] Each test piece was subjected to an extraction operation by being immersed in 1 mL of solution A for 24 hours. The extract obtained by the extraction operation was filtered by an injector and diluted 10 times. The obtained dilution was used to quantify the mass of the water-soluble organic solvent contained by gas chromatography (GC) under the following GC conditions.

[0200] -GC conditions-

[0201] GC device: Agilent 7890A (manufactured by Agilent Technology Co., Ltd.)

[0202] Column = DB-WAX (60 m) (manufactured by Agilent Technology)

[0203] Injection volume = 1 μL

[0204] Vaporization chamber temperature = 240°C

[0205] Gradient = 120°C (5 minutes) → 240°C / 15 minutes (heating rate = 8°C / min) → cooling to 120°C (cooling rate = 30°C / min)

[0206] An example of a method for measuring the water content using the image recorded material 1 is shown below.

[0207] Three rectangular test pieces of 24 mm×30 mm were collected from the image recorded material 1 .

[0208] The water content (mass standard) of each test piece was measured by Karl-Fischer titration using a trace moisture measuring device CA-200 and a heat removal unit (VA-230) manufactured by Mitsubishi Chemical Analytic Co., Ltd. AQUAMICRON AKX was used as the anolyte and AQUAMICRON CxU was used as the catholyte. As the mass of the blank, the mass of the substrate having the same volume as that of the substrate of each test piece was measured.

[0209] The content of the liquid component in the ink (ie, the image) after heat drying is also determined by the same method as the content of the liquid component in the ink (ie, the image) before heat drying.

[0210] Based on the content of liquid components in the ink (i.e., image) after heat drying and the content of liquid components in the ink (i.e., image) before heat drying, the residual amount of liquid components in the drying process is calculated (i.e., the content of liquid components in the ink after heat drying relative to the content of liquid components in the ink before heat drying (mass %)).

[0211] In the examples described below, the substrate was changed to an OPP (oriented polypropylene) substrate to produce an image recorded article, and the amount of liquid component remaining in the drying step was measured using the produced image recorded article and the OPP substrate as a blank.

[0212] Hereinafter, preferred embodiments of the ink used in the recording method of the present disclosure will be described.

[0213] 〔Ink〕

[0214] The ink in the recording method of the present disclosure (hereinafter also referred to as the ink in the present disclosure) contains water and particles including a polymer P and a polymerizable monomer M (hereinafter also referred to as "specific particles"), wherein the polymerizable monomer M includes a monomer (M-1) having a viscosity of 500 mPa·s or less at 25° C., and the content of the monomer (M-1) is 25% by mass to 80% by mass relative to the total solid content of the specific particles.

[0215] Hereinafter, each component that may be contained in the above-mentioned ink will be described.

[0216] <Specific Particles>

[0217] The ink contains at least one type of specific particles (ie, particles containing a polymer P and a polymerizable monomer M).

[0218] In the ink of the present disclosure, the inclusion of the polymer P and the polymerizable monomer M in the specific particles contributes to the ejection properties of the ink when ejected from an inkjet head (hereinafter, also simply referred to as “the ejection properties of the ink”).

[0219] A preferred embodiment of the ink in the present disclosure is an embodiment in which the polymerizable monomer M is retained in the specific particles in the ink before being applied on the substrate, and the polymerizable monomer M oozes out from the specific particles in the ink after being applied on the substrate.

[0220] (Polymerizable Monomer M)

[0221] The specific particles contain at least one polymerizable monomer M.

[0222] When the ink applied to the substrate is cured, the polymerizable monomer M contributes to linking the specific particles together, thereby improving the abrasion resistance and image quality of the image.

[0223] The polymerizable monomer M contained in the specific particles may be only one kind or two or more kinds.

[0224] As the polymerizable monomer M contained in the specific particles, the compounds described in paragraphs 0097 to 0105 of International Publication No. 2016 / 052053 can be used.

[0225] The molecular weight of the polymerizable monomer M is preferably 100 to 4,000, more preferably 100 to 2,000, more preferably 100 to 1,000, more preferably 100 to 900, more preferably 100 to 800, and particularly preferably 150 to 750.

[0226] As the polymerizable monomer M which may be contained in the specific particles, a radical polymerizable monomer is more preferred.

[0227] The radical polymerizable monomer has a radical polymerizable group in its molecular structure.

[0228] Preferred forms of the radical polymerizable group of the radical polymerizable monomer are the same as the preferred forms of the radical polymerizable group that the polymer P may contain as described above.

[0229] Examples of the radical polymerizable monomer include acrylic acid ester compounds, methacrylic acid ester compounds, styrene compounds, vinylnaphthalene compounds, N-vinyl heterocyclic compounds, unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.

[0230] The radical polymerizable monomer is preferably a compound having an ethylenically unsaturated group.

[0231] When the specific particles contain a radical polymerizable monomer, the specific particles may contain only one type of radical polymerizable monomer, or may contain two or more types of radical polymerizable monomers.

[0232] Examples of the acrylate compound include 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, tridecyl acrylate, 2-phenoxyethyl acrylate (PEA), bis(4-acryloxypolyethoxyphenyl)propane, oligoester acrylate, epoxy acrylate, isobornyl acrylate (IBOA), dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentyl acrylate, cyclotrimethylolpropane formal acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, octyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, 3,3,5-trimethylcyclohexylpropylene esters, 4-tert-butylcyclohexyl acrylate, isopentyl acrylate, stearyl acrylate, isostearyl acrylate, 2-ethylhexyl diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hydrogenated phthalic acid, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, vinyl ether acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyphthalic acid, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, lactone-modified acrylates, acryloylmorpholine, acrylamide, substituted acrylamides (for example, N-hydroxymethyl acrylamide and diacetone acrylamide) and the like;

[0233] Polyethylene glycol diacrylate, polypropylene glycol diacrylate, polybutylene glycol diacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate (HDDA), 1,9-nonanediol diacrylate (NDDA), 1,10-decanediol diacrylate (DDDA), 3-methylpentanediol diacrylate (3MPDDA), neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, bisphenol A ethylene oxide (EO) adduct diacrylate, bisphenol A propylene oxide (PO) adduct diacrylate, ethoxylated difunctional acrylate compounds such as bisphenol A diacrylate, hydroxy neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, alkoxylated dimethylol tricyclodecane diacrylate, polybutylene glycol diacrylate, alkoxylated cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, dioxanediol diacrylate, cyclohexanone dimethanol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate (TPGDA), and neopentyl glycol propylene oxide adduct diacrylate;

[0234] Trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol tetraacrylate, ethoxylated isocyanuric acid triacrylate, ε-caprolactone-modified tri-(2-acryloyloxyethyl) isocyanurate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, caprolactone-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxy tetraacrylate, glycerol propoxy triacrylate, ethoxylated dipentaerythritol hexaacrylate, caprolactam-modified dipentaerythritol hexaacrylate, propoxylated glycerol triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, and the like.

[0235] Examples of the methacrylate compound include monofunctional methacrylate compounds such as methyl methacrylate, n-butyl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, methoxypolyethylene glycol methacrylate, methoxytriethylene glycol methacrylate, hydroxyethyl methacrylate, phenoxyethyl methacrylate, and cyclohexyl methacrylate;

[0236] Bifunctional methacrylate compounds such as polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane and tetraethylene glycol dimethacrylate, and the like.

[0237] Examples of the styrene compound include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, and p-methoxy-β-methylstyrene.

[0238] Examples of the vinylnaphthalene compound include 1-vinylnaphthalene, methyl-1-vinylnaphthalene, β-methyl-1-vinylnaphthalene, 4-methyl-1-vinylnaphthalene, and 4-methoxy-1-vinylnaphthalene.

[0239] Examples of the N-vinyl heterocyclic compound include N-vinylcarbazole, N-vinylpyrrolidone, N-vinylethylacetamide, N-vinylpyrrole, N-vinylphenothiazine, N-vinylacetanilide, N-vinylethylacetamide, N-vinylsuccinimide, N-vinylphthalimide, N-vinylcaprolactam, and N-vinylimidazole.

[0240] Examples of other radical polymerizable monomers include allyl glycidyl ether, diallyl phthalate, triallyl trimellitate, and N-vinyl amides such as N-vinyl formamide.

[0241] Among these free radical polymerizable monomers, as a free radical polymerizable monomer with less than two functions, at least one selected from the following monomers is preferred: 1,6-hexanediol diacrylate (HDDA), 1,9-nonanediol diacrylate (NDDA), 1,10-decanediol diacrylate (DDDA), 3-methylpentanediol diacrylate (3MPDDA), neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate (TPGDA), cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, polyethylene glycol diacrylate, and polypropylene glycol diacrylate.

[0242] In addition, as a trifunctional or higher radical polymerizable monomer, at least one selected from the following monomers is preferred: trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, caprolactone-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxy tetraacrylate, glycerol propoxy triacrylate, ethoxylated dipentaerythritol hexaacrylate, caprolactam-modified dipentaerythritol hexaacrylate, propoxylated glycerol triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

[0243] The specific particles may include a combination of a difunctional or lower radical polymerizable monomer and a trifunctional or higher radical polymerizable monomer. In this case, the difunctional or lower radical polymerizable monomer mainly improves the adhesion between the film and the substrate, and the trifunctional or higher radical polymerizable monomer mainly improves the hardness of the film.

[0244] Examples of the combination of a difunctional or lower radical polymerizable monomer and a trifunctional or higher radical polymerizable monomer include a combination of a difunctional acrylate compound and a trifunctional acrylate compound, a combination of a difunctional acrylate compound and a pentafunctional acrylate compound, and a combination of a monofunctional acrylate compound and a tetrafunctional acrylate compound.

[0245] From the viewpoint of further improving the adhesion between the film and the substrate, at least one of the radical polymerizable monomers that may be contained in the specific particles is preferably a radical polymerizable monomer having a cyclic structure (hereinafter also referred to as a “cyclic radical polymerizable monomer”).

[0246] Examples of the cyclic radical polymerizable monomer include cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, isobornyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentyl acrylate, ethoxylated isocyanuric acid triacrylate, and ε-caprolactone-modified tri-(2-acryloyloxyethyl) isocyanurate.

[0247] In addition, the bifunctional or higher-functional cyclic radical polymerizable monomers described below can also be mentioned.

[0248] From the viewpoint of further improving the adhesion between the film and the substrate, at least one of the free radical polymerizable monomers that may be contained in the specific particles is preferably a polymerizable monomer containing one or more cyclic structures and two or more (meth)acryloyl groups in one molecule (hereinafter also referred to as "bifunctional or higher-functional cyclic free radical polymerizable monomer").

[0249] Examples of the difunctional or higher-functional cyclic radical polymerizable monomer include:

[0250] Tricyclodecane dimethanol di(meth)acrylate,

[0251] Bisphenol A ethylene oxide (EO) adduct di(meth)acrylate,

[0252] Bisphenol A propylene oxide (PO) adduct di(meth)acrylate,

[0253] Ethoxylated bisphenol A di(meth)acrylate,

[0254] Alkoxylated dimethylol tricyclodecane di(meth)acrylate,

[0255] Alkoxylated cyclohexanone dimethanol di(meth)acrylate,

[0256] Cyclohexanone dimethanol di(meth)acrylate, etc.

[0257] When the specific particles contain a radical polymerizable monomer, the proportion of the difunctional or higher-functional cyclic radical polymerizable monomer in the entire radical polymerizable monomer is preferably 10 to 100 mass %, more preferably 30 to 100 mass %, and particularly preferably 40 to 100 mass %.

[0258] In addition to the free radical polymerizable monomers listed above, commercially available products recorded in "Handbook of Crosslinking Agents" compiled by Shinzo Yamashita (Daiseisha, 1981); "UV·EB Curing Handbook (Raw Materials)" compiled by Kiyoshi Kato (1985, Polymer Publishing House); "Application and Market of UV·EB Curing Technology" compiled by Radtech Research Institute, page 79 (1989, CMC); "Polyester Resin Handbook" by Eiichiro Takiyama (1988, Nikkan Kogyo Shimbun), etc., as well as free radical polymerizable and crosslinking monomers known in the industry can also be used.

[0259] The content of the polymerizable monomer M (i.e., all polymerizable monomers in the specific particles) relative to the total solid content of the specific particles is not particularly limited as long as the condition that the content of the monomer (M-1) is 25% to 80% by mass relative to the total solid content of the specific particles is satisfied.

[0260] The content of the polymerizable monomer M is 25 to 90% by mass, more preferably 25 to 80% by mass, further preferably 25 to 75% by mass, and further preferably 25 to 70% by mass, based on the total solid content of the specific particles.

[0261] The content of the polymerizable monomer M is preferably 0.3% by mass to 20% by mass, more preferably 0.5% by mass to 15% by mass, and even more preferably 1% by mass to 10% by mass, based on the total amount of the ink.

[0262] The polymerizable monomer M includes a monomer (M-1) having a viscosity at 25° C. (hereinafter, also simply referred to as “viscosity”) of 500 mPa·s or less.

[0263] The monomer (M-1) is a polymerizable monomer having a relatively low viscosity than the above-mentioned viscosity and is a polymerizable monomer that easily oozes out of the specific particles.

[0264] The viscosity of the monomer (M-1) is a value measured using a viscometer.

[0265] As the viscometer, for example, VISCOMETER TV-22 (Toki Sangyo Co., Ltd.) can be used.

[0266] The monomer (M-1) may be any polymerizable monomer having a viscosity at 25°C of 500 mPa·s or less.

[0267] The lower limit of the viscosity of the monomer (M-1) is not particularly limited, and is, for example, 10 mPa·s.

[0268] As the monomer (M-1), a monomer having a molecular weight of 500 mPa·s or less can be appropriately selected from the radical polymerizable monomers exemplified above and used.

[0269] Examples of the monomer (M-1) include:

[0270] Pentaerythritol tetraacrylate,

[0271] Tricyclodecane dimethanol diacrylate,

[0272] Glyceryl propoxy triacrylate,

[0273] 1,12-Dodecanediol dimethacrylate,

[0274] Dicyclopentenyloxyethyl methacrylate,

[0275] 2-Phenoxyethyl acrylate,

[0276] Dicyclopentyl acrylate,

[0277] 1,6-Hexanediol diacrylate,

[0278] 1,9-nonanediol diacrylate,

[0279] 1,10-Decanediol diacrylate, etc.

[0280] The content of the monomer (M-1) is 25% by mass to 80% by mass based on the total solid content of the specific particles.

[0281] Since the content of the monomer (M-1) is 25% by mass or more based on the total solid content of the specific particles, the image quality and abrasion resistance are improved.

[0282] In detail, since the content of the monomer (M-1) is 25% by mass or more relative to the total solid content of the specific particles, in the ink applied to the substrate, before exposure, the polymerizable monomer M (particularly the monomer (M-1)) easily seeps out from the specific particles. Since the ink containing the seeped polymerizable monomer M (particularly the monomer (M-1)) is exposed, curing between the specific particles (the specific particles are connected to each other) is performed. As a result, the overall strength of the film is increased, the wear resistance of the image is improved, and the viscosity of the ink is promoted, thereby improving the image quality.

[0283] On the other hand, since the content of the monomer (M-1) is 80% by mass or less based on the total solid content of the specific particles, the content of the polymer P in the specific particles can be ensured, resulting in improved ink ejection properties.

[0284] From the viewpoint of further improving the ejection properties of the ink, the content of the monomer (M-1) is preferably 75% by mass or less, and more preferably 70% by mass or less, based on the total solid content of the specific particles.

[0285] As long as the polymerizable monomer M satisfies the condition of "the content of the monomer (M-1) is 25% to 80% by mass relative to the total solid content of the specific particles", it may also contain polymerizable monomers other than the monomer (M-1) (hereinafter also referred to as "monomer (M-2)").

[0286] From the viewpoint of further improving image quality and abrasion resistance, the proportion of monomer (M-1) in the total amount of polymerizable monomer M contained in the specific particles is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, and further preferably 80% by mass to 100% by mass.

[0287] When the polymerizable monomer M includes the monomer (M-1), the content of the monomer (M-1) is preferably 0.3% to 20% by mass, more preferably 0.5% to 15% by mass, and further preferably 1% to 10% by mass, relative to the total amount of the ink.

[0288] The monomer (M-1) preferably contains a monomer (M1A) having a viscosity at 25°C of 150 mPa·s or less.

[0289] Among the monomers (M-1), the monomer (M1A) is a polymerizable monomer that easily oozes out of the specific particles.

[0290] Therefore, when the monomer (M-1) contains the monomer (M1A), the image quality and abrasion resistance are further improved.

[0291] The monomer (M1A) may be any polymerizable monomer having a viscosity at 25° C. of 150 mPa·s or less.

[0292] The lower limit of the viscosity of the monomer (M1A) is not particularly limited, and is, for example, 10 mPa·s.

[0293] As the monomer (M1A), a monomer having an activity of 150 mPa·s or less can be appropriately selected from the radical polymerizable monomers exemplified above and used.

[0294] Examples of the monomer (M1A) include:

[0295] Tricyclodecane dimethanol diacrylate,

[0296] Glyceryl propoxy triacrylate,

[0297] 1,12-Dodecanediol dimethacrylate,

[0298] Dicyclopentenyloxyethyl methacrylate,

[0299] 2-Phenoxyethyl acrylate,

[0300] Dicyclopentyl acrylate,

[0301] 1,6-Hexanediol diacrylate,

[0302] 1,9-nonanediol diacrylate,

[0303] 1,10-Decanediol diacrylate, etc.

[0304] The monomer (M-1) may further contain a polymerizable monomer other than the monomer (M1A) (hereinafter also referred to as “monomer (M2A)”).

[0305] From the viewpoint of further improving image quality and abrasion resistance, the proportion of the monomer (M1A) in the total amount of the monomer (M-1) is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, and even more preferably 80% by mass to 100% by mass.

[0306] From the viewpoint of further improving image quality and abrasion resistance, the proportion of the monomer (M1A) in the total amount of the polymerizable monomer M contained in the specific particles is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, and further preferably 80% by mass to 100% by mass.

[0307] When the polymerizable monomer M includes the monomer (M1A), the content of the monomer (M1A) is preferably 0.3 to 20% by mass, more preferably 0.5 to 15% by mass, and further preferably 1 to 10% by mass, based on the total amount of the ink.

[0308] Examples of the radical polymerizable monomer selected as the polymerizable monomer M include those described in Japanese Patent Application Publication No. 7-159983, Japanese Patent Application Publication No. 7-31399, Japanese Patent Application Publication No. 8-224982, Japanese Patent Application Publication No. 10-863, Japanese Patent Application Publication No. 9-134011, and Japanese Patent Translation Publication No. 2004-514014.

[0309] Examples of commercially available radical polymerizable monomers include AH-600 (difunctional), AT-600 (difunctional), UA-306H (hexafunctional), UA-306T (hexafunctional), UA-306I (hexafunctional), UA-510H (decanofunctional), UF-8001G (difunctional), DAUA-167 (difunctional), Light Acrylate NPA (difunctional), Light Acrylate 3EG-A (difunctional) (all manufactured by Kyoeisha Chemical Co., Ltd.), SR339A (PEA, monofunctional), SR506 (IBOA, monofunctional), CD262 (difunctional), SR238 (HDDA, difunctional), SR341 (3MPDDA, difunctional), SR508 (difunctional), SR306H (difunctional), CD560 (difunctional), SR833S (difunctional), SR444 (trifunctional), SR454 (trifunctional), SR492 (trifunctional), SR499 (trifunctional), CD501 (trifunctional), SR502 (trifunctional), SR9020 (trifunctional), CD9021 (trifunctional), SR9035 (trifunctional) , SR494 (tetrafunctional), SR399E (pentafunctional) (all manufactured by Sartomer Co., Ltd.), A-NOD-N (NDDA, difunctional), A-DOD-N (DDDA, difunctional), A-200 (difunctional), APG-400 (difunctional), A-BPE-10 (difunctional), A-BPE-20 (difunctional), A-9300 (trifunctional), A-9300-1CL (trifunctional), A-TMPT (trifunctional), A-TMM-3L (trifunctional), A-TMMT (tetrafunctional), AD-TMP (tetrafunctional) (all manufactured by Shin-Nakamura Chemical Co., Ltd.), UV-7510B (trifunctional) (Nippon Synthetic Chemical Co., Ltd.), KAYARAD DPCA-30 (hexafunctional), KAYARAD DPEA-12 (hexafunctional) (all manufactured by Nippon Kayaku Co., Ltd.), etc.

[0310] In addition, as free radical polymerizable monomers, commercially available products such as NPGPODA (neopentyl glycol propylene oxide adduct diacrylate), SR531, SR285, SR256 (all manufactured by Sartomer Co., Ltd.), A-DHP (dipentaerythritol hexaacrylate, Shin-Nakamura Chemical Co., Ltd.), Aronix (registered trademark) M-156 (Toagosei Co., Ltd.), V-CAP (BASF Co., Ltd.), and Viscoat #192 (Osaka Organic Chemical Co., Ltd.) can be preferably used.

[0311] (Polymer P)

[0312] The specific particles comprise at least one polymer P.

[0313] The polymer P plays a role in retaining the polymerizable monomer M in specific particles in the ink before being ejected from the inkjet head, thereby contributing to improving the ejection properties of the ink.

[0314] The polymer P may be a chain polymer or a cross-linked polymer.

[0315] In the present disclosure, a chain polymer refers to a polymer that does not have a cross-linked structure, and a cross-linked polymer refers to a polymer that has a cross-linked structure.

[0316] The chain polymer may have a cyclic structure or a branched structure.

[0317] Regarding specific particles containing polymer P which is a chain polymer, for example, Japanese Patent No. 6584677 can be referred to.

[0318] As a preferred embodiment of the specific particles when the polymer P is a cross-linked polymer, there can be mentioned microcapsules including a shell composed of the polymer P which is a cross-linked polymer and a core containing a polymerizable monomer.

[0319] Regarding specific particles containing a polymer P which is a cross-linked polymer, for example, Japanese Patent No. 6510681 can be referred to.

[0320] -Weight average molecular weight (Mw)-

[0321] From the viewpoint of further improving the ejection properties of the ink, the weight average molecular weight (Mw) of the polymer P is preferably 3,000 to 200,000, more preferably 4,000 to 150,000, further preferably 5,000 to 100,000, further preferably 8,000 to 80,000, further preferably 10,000 to 50,000.

[0322] When the Mw of the polymer P is 3,000 or more, the abrasion resistance of the image is further improved.

[0323] When the Mw of the polymer P is 200,000 or less, the ejection properties of the ink are further improved.

[0324] In the present disclosure, the number average molecular weight (Mn) and the weight average molecular weight (Mw) refer to values ​​calculated by gel permeation chromatography (GPC) in terms of polystyrene.

[0325] As the column used, for example, TSKgel (registered trademark) SuperHZM-H, TSKgel (registered trademark) SuperHZ4000, and TSKgel (registered trademark) SuperHZ200 (all manufactured by Tosoh Corporation) are used.

[0326] -Glass transition temperature (Tg)-

[0327] The glass transition temperature (Tg) of the polymer P is not particularly limited.

[0328] From the viewpoint of improving the mobility of the polymer P and further improving the image quality (specifically, suppressing image roughness), the Tg of the polymer P is preferably 120°C or lower, more preferably 100°C or lower, further preferably 80°C or lower, and further preferably 70°C or lower.

[0329] On the other hand, the Tg of the polymer P is preferably 0°C or higher, more preferably 10°C or higher, further preferably 20°C or higher, and further preferably 30°C or higher.

[0330] In the present disclosure, the glass transition temperature (Tg) of a polymer refers to a value measured using differential scanning calorimetry (DSC).

[0331] The specific measurement of the glass transition temperature is carried out in accordance with the method described in JIS K 7121 (1987) or JIS K 6240 (2011).

[0332] The glass transition temperature in the present disclosure is an extrapolated glass transition start temperature (hereinafter, sometimes referred to as Tig).

[0333] The method for measuring the glass transition temperature will be described in more detail.

[0334] When obtaining the glass transition temperature, the temperature is maintained at about 50°C lower than the predicted glass transition temperature of the resin until the device is stable, and then heated to a temperature about 30°C higher than the temperature at the end of the glass transition at a heating rate of 20°C / min to produce a differential thermal analysis (DTA) curve or a DSC curve.

[0335] The extrapolated glass transition starting temperature (Tig), that is, the glass transition temperature in the present disclosure, is obtained as the temperature of the intersection of a straight line extending the baseline on the low temperature side of a DTA curve or a DSC curve to the high temperature side and a tangent drawn at the maximum point of the gradient of the curve of the step-like change portion of the glass transition.

[0336] When the ink contains two or more polymers P, the glass transition temperature (Tg) of the polymer P refers to a weighted average value of the glass transition temperatures of the respective polymers P.

[0337] Examples of the polymer P include urethane polymers, urethane urea polymers, urea polymers, acrylic polymers, polyesters, polyolefins, polystyrenes, polycarbonates, and polyamides.

[0338] Here, the urethane polymer refers to a polymer including a urethane bond and not including a urea bond, the urea polymer refers to a polymer including a urea bond and not including a urethane bond, and the urethane urea polymer refers to a polymer including a urethane bond and a urea bond.

[0339] The acrylic polymer refers to a polymer (homopolymer or copolymer) containing at least one raw material monomer selected from the group consisting of acrylic acid, acrylic acid derivatives (eg, acrylic acid esters), methacrylic acid, and methacrylic acid derivatives (eg, methacrylic acid esters).

[0340] -Key U-

[0341] The polymer P preferably includes a bond U which is at least one of a urethane bond and a urea bond. In other words, the polymer P is preferably a urethane polymer, a urethane urea polymer, or a urea polymer.

[0342] When the polymer P includes bonds U, in the ink deposited on the substrate, the specific particles are likely to interact with each other due to the interaction (e.g., hydrogen bonds) between the bonds U. Therefore, the specific particles are more likely to be linked to each other due to the polymerization of the polymerizable monomer M (specifically, monomer (M-1)) that oozes out of the specific particles. As a result, the curing between the specific particles is more likely to proceed, and the abrasion resistance of the image is further improved.

[0343] Bond U preferably comprises a urethane bond.

[0344] In other words, the polymer P preferably includes a urethane bond and no urea bond, or includes a urethane bond and a urea bond.

[0345] -Hydrophilic Group-

[0346] The polymer P preferably comprises at least one hydrophilic group.

[0347] This contributes to the dispersion stability of the specific particles in the ink, and as a result, the storage stability of the ink is further improved.

[0348] From the viewpoint of further improving the storage stability of the ink, the hydrophilic group is preferably an anionic group or a nonionic group, and more preferably an anionic group.

[0349] For example, when comparing anionic groups and nonionic groups of the same molecular weight, the anionic group has a superior effect of improving the storage stability of the ink. That is, the anionic group (particularly preferably at least one selected from the group consisting of a carboxyl group and a salt of a carboxyl group) can fully exert the effect of improving the storage stability of the ink even when its molecular weight is small.

[0350] Examples of the nonionic group include a group having a polyether structure, and a monovalent group containing a polyalkyleneoxy group is preferred.

[0351] The anionic group may or may not be neutralized.

[0352] Examples of the unneutralized anionic group include a carboxyl group, a sulfo group, a sulfate group, a phosphonic acid group, and a phosphoric acid group.

[0353] The neutralized anionic group refers to an anionic group in the form of a "salt" (e.g., a salt of a carboxyl group (e.g., -COONa)). Examples of the neutralized anionic group include salts of a carboxyl group, salts of a sulfonic group, salts of a sulfate group, salts of a phosphonic acid group, and salts of a phosphoric acid group.

[0354] Neutralization can be performed using, for example, an alkali metal hydroxide (eg, sodium hydroxide, potassium hydroxide, etc.) or an organic amine (eg, triethylamine, etc.).

[0355] As the hydrophilic group in the polymer P, from the viewpoint of further improving the storage stability of the ink, an anionic group is preferred, and at least one selected from the group consisting of a carboxyl group, a carboxyl salt, a sulfonate group, a sulfonate salt, a sulfate group, a sulfate salt, a phosphonic acid group, a phosphonic acid salt, a phosphoric acid group, and a phosphoric acid salt is more preferred, and at least one selected from the group consisting of a carboxyl group, a carboxyl salt, a sulfonate group, and a sulfonate salt is further preferred.

[0356] As the "salt" among the above-mentioned salts of carboxyl group, sulfonate group, sulfate group, phosphonate group and phosphoric acid group, an alkali metal salt or an organic amine salt is preferred, and an alkali metal salt is more preferred.

[0357] As the alkali metal in the alkali metal salt, K or Na is preferred.

[0358] In addition, in the case where the polymer P contains an anionic group (for example, at least one selected from the group consisting of a carboxyl group and a salt of a carboxyl group) as a hydrophilic group, when the total millimole number of anionic groups (for example, a carboxyl group and a salt of a carboxyl group) contained in 1 g of the polymer P is taken as the acid value of the polymer P, from the viewpoint of dispersion stability, the acid value of the polymer P is preferably 0.10 mmol / g to 2.00 mmol / g, and more preferably 0.30 mmol / g to 1.50 mmol / g.

[0359] When the polymer P has an anionic group as the hydrophilic group, the neutralization degree of the anionic group in the polymer P is preferably 50% to 100%, and more preferably 70% to 90%.

[0360] Here, the degree of neutralization refers to the ratio of the "number of neutralized anionic groups" in the polymer P to the "total number of unneutralized anionic groups (e.g., carboxyl groups) and the number of neutralized anionic groups (e.g., salts of carboxyl groups)" (i.e., the ratio [number of neutralized anionic groups / (number of unneutralized anionic groups + number of neutralized anionic groups)]).

[0361] The degree of neutralization of the anionic groups in the polymer P can be measured by neutralization titration.

[0362] -Polymerizable group-

[0363] The specific particles contain not only the polymer P but also the aforementioned polymerizable monomer M (ie, a compound containing a polymerizable group). The polymerizable monomer M contributes to improving the wear resistance of the film. Therefore, the polymer P does not necessarily need to contain a polymerizable group.

[0364] However, from the viewpoint of further improving the abrasion resistance of the film, the polymer P may contain a polymerizable group.

[0365] As the polymerizable group which may be contained in the polymer P, a photopolymerizable group or a thermal polymerizable group is preferred.

[0366] As the photopolymerizable group, a free radical polymerizable group is preferred, a group containing an ethylenic double bond is more preferred, and a (meth)acryloyl group, an allyl group, a styryl group, or a vinyl group is further preferred. As the free radical polymerizable group, from the viewpoint of free radical polymerization reactivity and the hardness of the formed film, a (meth)acryloyl group is particularly preferred.

[0367] As the heat-polymerizable group, an epoxy group, an oxetanyl group, an aziridine group, an azetidinyl group, a keto group, an aldehyde group, or a blocked isocyanate group is preferred.

[0368] The polymer P may contain only one type of polymerizable group, or may contain two or more types.

[0369] Whether the polymer P contains a polymerizable group can be confirmed by, for example, Fourier transform infrared spectroscopy (FT-IR) analysis.

[0370] When the number of millimoles of ethylenic double bonds in 1 g of polymer P is set as the C=C valence of polymer P, from the viewpoint of further improving the hardness of the image, the C=C valence of polymer P is preferably 0.05 mmol or more, more preferably 0.10 mmol / g or more, further preferably 0.30 mmol / g or more, and particularly preferably 0.50 mmol / g or more.

[0371] From the viewpoint of further improving the water resistance and alcohol resistance of the image, the C=C value of the polymer P is preferably 0.05 mmol or more, more preferably 0.10 mmol / g or more, further preferably 0.30 mmol / g or more, further preferably 0.50 mmol / g or more, further preferably 0.60 mmol / g or more, and particularly preferably 0.70 mmol / g or more.

[0372] On the other hand, from the viewpoint of improving the time-dependent curing property of the ink (i.e., suppressing the time-dependent decrease in the curing property of the ink), the C=C valence of the polymer P is preferably 4.00 mmol / g or less, more preferably 3.00 mmol / g or less, further preferably 2.00 mmol / g or less, and particularly preferably 1.50 mmol / g or less.

[0373] The polymer P may include other structures besides the above-mentioned structures (ie, the bond U, the hydrophilic group, and the polymerizable group).

[0374] Examples of other structures include a polysiloxane bond (ie, a divalent polysiloxane group), a monovalent polysiloxane group, a monovalent fluorinated hydrocarbon group, and a divalent fluorinated hydrocarbon group.

[0375] -Preferred Structure of Polymer P-

[0376] The polymer P preferably contains a structural unit derived from an isocyanate compound (hereinafter, also referred to as "NCO") and a structural unit derived from a compound containing an active hydrogen group.

[0377] The polymer P of the above preferred embodiment includes a bond U formed by a reaction between an isocyanate group of an isocyanate compound and an active hydrogen group of an active hydrogen group-containing compound.

[0378] The active hydrogen group is preferably a hydroxyl group, a primary amino group or a secondary amino group.

[0379] For example, a urethane group is formed by the reaction of an isocyanate group and a hydroxyl group.

[0380] In addition, a urea group is formed by the reaction of an isocyanate group and a primary or secondary amino group.

[0381] Hereinafter, the isocyanate compound and the active hydrogen group-containing compound serving as raw materials of the polymer P having the above-mentioned preferred structure may be referred to as raw material compounds.

[0382] The isocyanate compound as a raw material compound may be one kind or two or more kinds.

[0383] The active hydrogen group-containing compound as the raw material compound may be only one kind or two or more kinds.

[0384] At least one kind of isocyanate compound among the raw material compounds is preferably a difunctional or higher functional isocyanate compound.

[0385] At least one compound containing an active hydrogen group as the raw material compound is preferably a compound containing two or more active hydrogen groups.

[0386] Among the raw material compounds, at least one of the isocyanate compound and the compound containing an active hydrogen group preferably contains a hydrophilic group. Thus, it is easy to produce a polymer P containing a hydrophilic group. In this case, at least a part of the hydrophilic groups in the finally obtained polymer P may be groups obtained by neutralizing the hydrophilic groups in the raw material compound.

[0387] A more preferred embodiment is an embodiment in which at least one of the compounds containing an active hydrogen group among the raw material compounds is a compound containing an active hydrogen group and a hydrophilic group.

[0388] When the polymer P contains a polymerizable group, it is preferred that at least one of the isocyanate compound and the compound containing an active hydrogen group among the raw material compounds contains a polymerizable group. This makes it easy to produce the polymer P containing a polymerizable group.

[0389] A more preferred embodiment is an embodiment in which at least one of the compounds containing an active hydrogen group among the raw material compounds is a compound containing an active hydrogen group and a polymerizable group.

[0390] As mentioned above, the polymer P can be a chain polymer or a cross-linked polymer.

[0391] The chain polymer as the polymer P can be produced by reacting a difunctional isocyanate compound with a compound containing two active hydrogen groups.

[0392] The crosslinked polymer as the polymer P can be produced by reacting a trifunctional or higher functional isocyanate compound with a compound containing two or more active hydrogen groups.

[0393] The crosslinked polymer as the polymer P can also be produced by reacting a difunctional isocyanate compound with a compound containing three or more active hydrogen groups.

[0394] Preferred raw material compounds are described below.

[0395] -Isocyanate compounds-

[0396] The isocyanate compound is preferably a difunctional or higher-functional isocyanate compound, and more preferably a difunctional to hexafunctional isocyanate compound.

[0397] When a difunctional isocyanate compound is used as a raw material compound, the polymer P contains the following structural unit (P1) as a structural unit derived from the difunctional isocyanate compound.

[0398] [Chemical formula 1]

[0399]

[0400] In the structural unit (P1), L 1 It represents a divalent organic group having 1 to 20 carbon atoms, and * represents a bonding position.

[0401] As L 1 Specific examples include residues obtained by removing two isocyanate groups (NCO groups) from the difunctional isocyanate compounds described in the following specific examples.

[0402] Specific examples of the difunctional isocyanate compound are as follows. However, the difunctional isocyanate compound is not limited to the following specific examples.

[0403] [Chemical formula 2]

[0404]

[0405] Furthermore, as the difunctional isocyanate compound, a difunctional isocyanate compound derived from the above specific examples may be used, for example, DURANATE (registered trademark) D101, D201, A101 (manufactured by Asahi Kasei Corporation) and the like.

[0406] In addition, the trifunctional or higher-functional isocyanate compound is preferably a reaction product of at least one selected from the group consisting of difunctional isocyanate compounds and at least one selected from the group consisting of compounds containing three or more active hydrogen groups (for example, trifunctional or higher-functional polyol compounds, trifunctional or higher-functional polyamine compounds, and trifunctional or higher-functional polythiol compounds).

[0407] The number of moles (number of molecules) of the difunctional isocyanate compound to be reacted with the compound containing three or more active hydrogen groups is preferably 0.6 times or more, more preferably 0.6 times to 5 times, further preferably 0.6 times to 3 times, and further preferably 0.8 times to 2 times the number of moles of the active hydrogen groups in the compound containing three or more active hydrogen groups (the equivalent number of active hydrogen groups).

[0408] Examples of the difunctional isocyanate compound for forming a trifunctional or higher-functional isocyanate compound include the difunctional isocyanate compounds described above as specific examples.

[0409] Examples of the compound containing three or more active hydrogen groups for forming a trifunctional or higher functional isocyanate compound include compounds described in paragraphs 0057 to 0058 of International Publication No. 2016 / 052053.

[0410] Examples of the trifunctional or higher-functional isocyanate compound include addition-type trifunctional or higher-functional isocyanate compounds, isocyanurate-type trifunctional or higher-functional isocyanate compounds, and biuret-type trifunctional or higher-functional isocyanate compounds.

[0411] Commercially available products of addition-type trifunctional or higher-functional isocyanate compounds include TAKENATE (registered trademark) D-102, D-103, D-103H, D-103M2, P49-75S, D-110N, D-120N, D-140N, and D-160N (all manufactured by Mitsui Chemicals, Inc.), Desmodur (registered trademark) L75 and UL57SP (Sumika Bayer Polyurethane Co., Ltd.), Coronate (registered trademark) HL and L (Tosoh Corporation), and P301-75E (Asahi Kasei Corporation).

[0412] Examples of commercially available isocyanurate-type trifunctional or higher-functional isocyanate compounds include TAKENATE (registered trademark) D-127N, D-170N, D-170HN, D-172N, and D-177N (all manufactured by Mitsui Chemicals, Inc.), SUMIDURN 3300, Desmodur (registered trademark) N3600, N3900, and Z4470BA (all manufactured by Sumika Bayer Polyurethane Co., Ltd.), CORONATE (registered trademark) HX and HK (all manufactured by Tosoh Corporation), and DURANATE (registered trademark) TPA-100, TKA-100, TSA-100, TSS-100, TLA-100, and TSE-100 (all manufactured by Asahi Kasei Corporation).

[0413] Commercially available products of biuret-type trifunctional or higher-functional isocyanate compounds include TAKENATE (registered trademark) D-165N and NP1100 (both manufactured by Mitsui Chemicals, Inc.), Desmodur (registered trademark) N3200 (Sumika Bayer Polyurethane Co., Ltd.), and DURANATE (registered trademark) 24A-100 (Asahi Kasei Corporation).

[0414] At least one of the isocyanate compounds as the raw material compound may be an isocyanate compound containing a hydrophilic group. For the isocyanate compound containing a hydrophilic group, reference can be made to paragraphs 0112 to 0118 and paragraphs 0252 to 0254 of International Publication No. 2016 / 052053.

[0415] At least one of the isocyanate compounds as the raw material compound may be an isocyanate compound containing a polymerizable group. For the isocyanate compound containing a polymerizable group, reference can be made to paragraphs 0084 to 0089, 0203, and 0205 of International Publication No. 2016 / 052053.

[0416] -Compounds containing active hydrogen groups-

[0417] As the compound containing an active hydrogen group, a compound containing two or more active hydrogen groups is preferable.

[0418] As the compound containing two or more active hydrogen groups, a polyol compound (ie, a compound having two or more hydroxyl groups) or a polyamine compound (ie, a compound having two or more amino groups) is more preferable.

[0419] When a compound containing an active hydrogen group and a hydrophilic group is used as a raw material compound, the polymer P preferably contains at least one structural unit (P0) described below.

[0420] [Chemical formula 3]

[0421]

[0422] In the structural unit (P0),

[0423] L 0 represents a divalent organic group,

[0424] Y 1 and Y 2 Each independently represents an oxygen atom, a sulfur atom, or -NR 1 -base,

[0425] R 1 represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms,

[0426] *Indicates bonding position.

[0427] In the structural unit (P0), L 0 The divalent organic group represented may be a group composed of carbon atoms and hydrogen atoms, or a group containing carbon atoms and hydrogen atoms and a hetero atom (for example, an oxygen atom, a nitrogen atom, a sulfur atom, etc.).

[0428] L 0 The divalent organic group represented may include at least one of a hydrophilic group and a polymerizable group.

[0429] As L 0A specific example of is a residue obtained by removing two active hydrogen groups from the specific examples of the compound containing an active hydrogen group described later.

[0430] As R 1 , preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms.

[0431] Y 1 and Y 2 Preferably, each independently is an oxygen atom or -NR 1 - group, more preferably an oxygen atom.

[0432] Specific examples of the diol compound as the compound containing an active hydrogen group are shown below, but the compound containing an active hydrogen group is not limited to the following specific examples.

[0433] [Chemical formula 4]

[0434]

[0435]

[0436] In compounds (12) to (15), nC7H 15 、nC9H 19 、nC 11 H 23 , and nC 17 H 35 They represent n-heptyl, n-nonyl, n-undecyl and n-heptadecyl, respectively.

[0437] Compound (16) PPG is polypropylene glycol, and n is the number of repetitions.

[0438] Compound (16-2) PEG is polyethylene glycol, and n is the number of repetitions.

[0439] Compound (17) PEs is a polyester diol, n is a repeating number, Ra and two Rb are independently a divalent hydrocarbon group having 2 to 25 carbon atoms. The n Ra in compound (17) PEs may be the same or different. The (n+1) Rb in compound (17) PEs may be the same or different.

[0440] Compound (18) PC is a polycarbonate diol, n is the number of repetitions, and (n+1) Rcs are each independently an alkylene group having 2 to 12 carbon atoms (preferably 3 to 8, more preferably 3 to 6). The (n+1) Rcs in compound (18) PC may be the same or different.

[0441] Compound (19) PCL is polycaprolactone diol, n and m are repeating numbers, and Rd is an alkylene group having 2 to 25 carbon atoms.

[0442] -Compound containing an active hydrogen group and a polymerizable group-

[0443] Examples of the compound containing an active hydrogen group also include compounds containing an active hydrogen group and a polymerizable group.

[0444] A compound containing an active hydrogen group and a polymerizable group is suitable as a compound for introducing a polymerizable group into the polymer P (hereinafter also referred to as a "polymerizable group-introducing compound").

[0445] Specific examples of the diol compound as the compound containing an active hydrogen group and a polymerizable group are shown below, but the compound containing an active hydrogen group and a polymerizable group is not limited to the following specific examples.

[0446] [Chemical formula 5]

[0447]

[0448] Regarding the compound containing an active hydrogen group and a polymerizable group, the description in paragraphs 0075 to 0089 of International Publication No. 2016 / 052053 can be appropriately referred to.

[0449] -Compounds containing active hydrogen groups and hydrophilic groups-

[0450] Examples of the compound containing an active hydrogen group include compounds containing an active hydrogen group and a hydrophilic group.

[0451] A compound containing an active hydrogen group and a hydrophilic group is suitable as a compound for introducing a hydrophilic group into the polymer P (hereinafter also referred to as a "hydrophilic group-introducing compound").

[0452] When a compound containing an active hydrogen group and a hydrophilic group is used as a raw material compound, the polymer P preferably contains the following structural unit (P2).

[0453] [Chemical formula 6]

[0454]

[0455] In the structural unit (P2),

[0456] L 21 represents a trivalent organic group having 1 to 20 carbon atoms,

[0457] L 22 represents a single bond or a divalent organic group having 1 to 20 carbon atoms,

[0458] A 1 represents a carboxyl group, a carboxyl salt, a sulfonic group, or a sulfonic group salt,

[0459] *Indicates bonding position.

[0460] L 21 The trivalent organic group having 1 to 20 carbon atoms represented by is preferably 2 to 20 carbon atoms, more preferably 3 to 20 carbon atoms, and even more preferably 4 to 20 carbon atoms.

[0461] As L 21 The trivalent organic group represented is preferably a trivalent hydrocarbon group, or a group in which at least one carbon atom in the trivalent hydrocarbon group is substituted with a heteroatom (preferably an oxygen atom, a sulfur atom, or a nitrogen atom).

[0462] L 22 The number of carbon atoms in the divalent organic group having 1 to 20 carbon atoms represented by is preferably 1 to 10, more preferably 1 to 6.

[0463] As L 22 The divalent organic group represented is preferably a divalent hydrocarbon group (preferably an alkylene group) or a group in which at least one carbon atom in a divalent hydrocarbon group (preferably an alkylene group) is substituted with an oxygen atom or a sulfur atom (preferably an oxygen atom).

[0464] L 22 It can also be a single bond.

[0465] Specific examples of compounds containing active hydrogen groups and hydrophilic groups are shown below, but the compounds containing active hydrogen groups and hydrophilic groups are not limited to the following specific examples. The carboxyl group and the sulfonic group in the following specific examples may be neutralized (that is, they may be salts of carboxyl groups and salts of sulfonic groups).

[0466] [Chemical formula 7]

[0467]

[0468] Regarding the compound containing an active hydrogen group and a hydrophilic group, the description in paragraphs 0112 to 0118 and paragraphs 0252 to 0254 of International Publication No. 2016 / 052053 can be appropriately referred to.

[0469] The content of the polymer P is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, further preferably 30 to 70% by mass, and further preferably 40 to 60% by mass, based on the total solid content of the specific particles.

[0470] The content of the polymer P is preferably 0.3% by mass to 20% by mass, more preferably 0.5% by mass to 15% by mass, and even more preferably 1% by mass to 10% by mass, based on the total amount of the ink.

[0471] (Free Radical Polymerization Initiator)

[0472] The specific particles may contain at least one kind of radical polymerization initiator.

[0473] In the present disclosure, the radical polymerization initiator refers to a compound that absorbs light to generate radicals.

[0474] When the specific particles contain a radical polymerizable monomer as the polymerizable monomer, the specific particles preferably contain at least one kind of radical polymerization initiators.

[0475] Thereby, the wear resistance and adhesion of the formed film are further improved.

[0476] This is considered to be because the distance between the radical polymerizable group in the radical polymerizable monomer and the radical polymerization initiator becomes closer, thereby increasing the curing sensitivity (hereinafter, also simply referred to as "sensitivity") of the film.

[0477] In addition, when the specific particles contain a free radical polymerization initiator, a free radical polymerization initiator that was previously difficult to use due to its low dispersibility or solubility in water despite its high sensitivity can be used (for example, a free radical polymerization initiator having a solubility in water of 1.0% by mass or less at 25° C.). As a result, the range of choices for the free radical polymerization initiator used is expanded, and the range of choices for the light source used is also expanded. Therefore, the curing sensitivity can be improved compared to the past.

[0478] Specific examples of the radical polymerization initiator that is difficult to use due to its low dispersibility or solubility in water despite its high sensitivity include carbonyl compounds and acylphosphine oxide compounds described below, and acylphosphine oxide compounds are preferred.

[0479] Thus, in the water dispersion and ink of the present disclosure, by making the specific particles contain a substance having low solubility in water, the substance can be contained in the water-based composition, that is, the water dispersion and ink of the present disclosure.

[0480] In addition, the water dispersion and ink in which the specific particles contain a radical polymerization initiator also have excellent storage stability compared to conventional photocurable compositions. This is believed to be because the radical polymerization initiator is contained in the specific particles, thereby suppressing the aggregation or precipitation of the radical polymerization initiator.

[0481] As the radical polymerization initiator, for example, the description in paragraphs 0091 to 0094 of International Publication No. 2016 / 052053 can be appropriately referred to.

[0482] As the free radical polymerization initiator, more preferred are (a) carbonyl compounds such as aromatic ketones or (b) acylphosphine oxide compounds, and specific examples thereof include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (e.g., IRGACURE (registered trademark) 819 manufactured by BASF), 2-(dimethylamino)-1-(4-morpholinophenyl)-2-benzyl-1-butanone (e.g., IRGACURE (registered trademark) 369 manufactured by BASF), 2-methyl-1- -(4-methylthiophenyl)-2-morpholinopropane-1-one (for example, IRGACURE (registered trademark) 907 manufactured by BASF), 1-hydroxy-cyclohexyl-phenyl-ketone (for example, IRGACURE (registered trademark) 184 manufactured by BASF), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (for example, DAROCUR (registered trademark) TPO, LUCIRIN (registered trademark) TPO (both manufactured by BASF)), etc.

[0483] Among them, from the viewpoint of improving sensitivity and adaptability to LED light, as a free radical polymerization initiator, (b) an acylphosphine oxide compound is preferred, and a monoacylphosphine oxide compound (particularly preferably 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide) or a bisacylphosphine oxide compound (particularly preferably bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide) is more preferred.

[0484] The wavelength of the LED light is preferably 355 nm, 365 nm, 385 nm, 395 nm, or 405 nm.

[0485] The specific particles in the form containing a radical polymerization initiator can be produced, for example, by emulsifying a mixture of an oil phase component and an aqueous phase component containing a polymer P (or a raw material compound for producing the polymer P), a radical polymerizable monomer, and a photopolymerization initiator.

[0486] The content of the radical polymerization initiator is preferably 0.1% by mass to 15% by mass, more preferably 0.5% by mass to 10% by mass, and even more preferably 1% by mass to 6% by mass, based on the total solid content of the specific particles.

[0487] (Sensitizer)

[0488] The specific particles may contain at least one of the sensitizers.

[0489] When the specific particles contain at least one kind of photopolymerization initiators, the specific particles preferably contain at least one kind of sensitizers.

[0490] When the specific particles contain a sensitizer, decomposition of the photopolymerization initiator by irradiation with active energy rays can be further accelerated.

[0491] The sensitizer is a substance that absorbs specific active energy rays and becomes an electronically excited state. The sensitizer that becomes an electronically excited state contacts the photopolymerization initiator and causes electron transfer, energy transfer, heat generation, etc. This promotes the chemical changes of the photopolymerization initiator, i.e., decomposition, generation of free radicals, acid or base, etc.

[0492] Examples of the sensitizer include benzophenone, thioxanthone, isopropylthioxanthone, anthraquinone, 3-acylcoumarin derivatives, terphenyl, styryl ketone, 3-(aroylmethylene)thiazoline, camphorquinone, eosin, rhodamine, and erythrosine.

[0493] Furthermore, as the sensitizer, a compound represented by the general formula (i) described in JP-A-2010-24276, a compound represented by the general formula (I) described in JP-A-6-107718, and the like can also be appropriately used.

[0494] Among the above, as a sensitizer, from the viewpoint of adaptability to LED light and reactivity with a photopolymerization initiator, at least one selected from thioxanthone, isopropylthioxanthone, and benzophenone is preferred, at least one selected from thioxanthone and isopropylthioxanthone is more preferred, and isopropylthioxanthone is further preferred.

[0495] When the specific particles contain a sensitizer, the specific particles may contain one type of sensitizer alone or two or more types of sensitizers.

[0496] When the specific particles contain a sensitizer, the content of the sensitizer is preferably 0.1 to 20% by mass, more preferably 0.2 to 15% by mass, and even more preferably 0.3 to 10% by mass, relative to the solid content of the specific particles.

[0497] The specific particles containing a photopolymerization initiator and a sensitizer can be produced, for example, by emulsifying a mixture of an oil phase component containing a polymer P (or a raw material compound for producing the polymer P), a radical polymerizable monomer, a photopolymerization initiator and a sensitizer and a water phase component.

[0498] (Other ingredients)

[0499] The specific particles may contain other components than the above components.

[0500] Examples of other components include compounds containing at least one selected from the group consisting of a polysiloxane bond (ie, a divalent polysiloxane group), a monovalent polysiloxane group, a monovalent fluorinated hydrocarbon group, and a divalent fluorinated hydrocarbon group.

[0501] (Method for producing aqueous dispersion of specific particles)

[0502] The ink in the present disclosure can be produced by preparing an aqueous dispersion of the specific particles containing the above-mentioned specific particles and water, and adding other components to the obtained aqueous dispersion as necessary.

[0503] In addition, the ink in the present disclosure is a form of a water dispersion of specific particles, and therefore, depending on the composition of the ink, the ink can also be produced directly (that is, without adding other components) as a water dispersion of specific particles.

[0504] The method for producing the aqueous dispersion of specific particles is not particularly limited.

[0505] As a method for producing an aqueous dispersion of specific particles, the following production method A and production method B are exemplified.

[0506] -Method A-

[0507] Preparation method A includes a step of obtaining an aqueous dispersion of specific particles by mixing and emulsifying an oil phase component containing an organic solvent, a polymer P, and a polymerizable monomer and an aqueous phase component containing water.

[0508] The production method A is suitable as a method for producing an aqueous dispersion containing specific particles of the polymer P in the form of a chain polymer.

[0509] Regarding the production method A, reference may be made to known documents such as Japanese Patent No. 6584677.

[0510] -Method B-

[0511] Preparation method B has a step of obtaining an aqueous dispersion of specific particles by mixing an oil phase component containing an organic solvent, a raw material compound of the polymer P (for example, a trifunctional or higher-functional isocyanate compound, a compound having two or more active hydrogen groups, etc.) and a polymerizable monomer with an aqueous phase component containing water and emulsifying them.

[0512] The production method B is suitable as a method for producing an aqueous dispersion containing specific particles (for example, microcapsules) of the polymer P in the form of a cross-linked polymer.

[0513] Regarding Preparation Method B, reference may be made to known documents such as International Publication No. 2016 / 052053.

[0514] (Total solid content of specific particles in ink)

[0515] The total solid content of the specific particles in the ink is preferably 2 to 30% by mass, more preferably 3 to 25% by mass, further preferably 4 to 20% by mass, further preferably 5 to 15% by mass, relative to the total amount of the ink.

[0516] When the total solid content of the specific particles is 2% by mass or more relative to the total amount of the ink in the present disclosure, the image quality and abrasion resistance are further improved.

[0517] When the total solid content of the specific particles is 30% by mass or less based on the total amount of the ink in the present disclosure, the image quality and abrasion resistance are further improved.

[0518] The total solid content of specific particles in the ink referred to here means the total solid content of specific particles in the ink before ejection (ie, ejection from the inkjet head).

[0519] (Volume average dispersed particle size of specific particles)

[0520] The volume average dispersed particle size of the specific particles in the ink is not particularly limited, but is preferably 0.01 μm to 10 μm, more preferably 0.01 μm to 5 μm, further preferably 0.05 μm to 1 μm, further preferably 0.05 μm to 0.5 μm, further preferably 0.05 μm to 0.3 μm from the viewpoint of dispersion stability.

[0521] In the present disclosure, “volume average dispersed particle size” refers to a value measured by a light scattering method. The volume average dispersed particle size of specific particles by the light scattering method is measured using, for example, LA-960 (Horiba, Ltd.).

[0522] <Water>

[0523] The ink in the present disclosure contains water.

[0524] The water content is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, and particularly preferably 50% by mass or more, based on the total amount of the ink in the present disclosure.

[0525] The upper limit of the water content relative to the total amount of the ink in the present disclosure is appropriately determined depending on the contents of other components, and is, for example, 99% by mass, preferably 95% by mass, and more preferably 90% by mass.

[0526] <Water-soluble organic solvent>

[0527] The ink of the present disclosure contains at least one water-soluble organic solvent.

[0528] This ensures that ink can be ejected from the inkjet head.

[0529] In the present disclosure, the "water-soluble" in the "water-soluble organic solvent" refers to the property of dissolving 1 g or more in 100 g of water at 25°C.

[0530] The amount of the water-soluble organic solvent that dissolves in 100 g of water at 25° C. is preferably 5 g or more, more preferably 10 g or more.

[0531] The content of the water-soluble organic solvent is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, further preferably 8 to 15% by mass, and further preferably 10 to 20% by mass, based on the total amount of the ink.

[0532] When the content of the water-soluble organic solvent is 1% by mass or more, the ejection properties of the ink are further improved.

[0533] When the content of the water-soluble organic solvent is 50% by mass or less, the storage stability of the ink is further improved.

[0534] Specific examples of the water-soluble organic solvent are as follows.

[0535] Alcohols (e.g., methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.)

[0536] Polyvalent alcohols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexylene glycol, pentylene glycol, glycerol, hexanetriol, thiodiglycol, 2-methylpropanediol, etc.)

[0537] Polyvalent alcohol ethers (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, tripropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.)

[0538] Amines (e.g., ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.)

[0539] Amides (e.g., formamide, N,N-dimethylformamide, N,N-dimethylacetamide, etc.)

[0540] Heterocyclic compounds (e.g., 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone, etc.)

[0541] Sulfoxides (e.g. dimethyl sulfoxide, etc.)

[0542] Sulfones (e.g., sulfolane, etc.)

[0543] Others (urea, acetonitrile, acetone, etc.)

[0544] (Water-soluble organic solvent (S-1) having a boiling point of 190°C or less)

[0545] The water-soluble organic solvent in the ink of the present disclosure preferably contains at least one water-soluble organic solvent (S-1) having a boiling point of 190° C. or less (hereinafter, also simply referred to as “water-soluble organic solvent (S-1)”).

[0546] This further improves the blocking resistance of the recorded image.

[0547] In the present disclosure, excellent blocking resistance means a property in which blocking of an image (that is, a phenomenon in which an object to be contacted sticks to an image when the object to be contacted is placed on the image) is suppressed.

[0548] In the present disclosure, the boiling point refers to the boiling point at 1 atmosphere pressure (101325 Pa).

[0549] Examples of the water-soluble organic solvent (S-1) include propylene glycol (boiling point 188°C), propylene glycol monomethyl ether (boiling point 121°C), ethylene glycol monomethyl ether (boiling point 124°C), propylene glycol monoethyl ether (boiling point 133°C), ethylene glycol monoethyl ether (boiling point 135°C), propylene glycol monopropyl ether (boiling point 149°C), ethylene glycol monopropyl ether (boiling point 151°C), propylene glycol monobutyl ether (boiling point 170°C), ethylene glycol monobutyl ether (boiling point 171°C), 2-ethyl-1-hexanol (boiling point 187°C), dipropylene glycol monomethyl ether (boiling point 188°C), diethylene glycol dimethyl ether (boiling point 162°C), diethylene glycol diethyl ether (boiling point 188°C), and dipropylene glycol dimethyl ether (boiling point 175°C).

[0550] From the viewpoint of ink drying properties, the proportion of the water-soluble organic solvent (S-1) in the water-soluble organic solvent in the ink of the present disclosure is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0551] The proportion of the water-soluble organic solvent (S-1) having a boiling point of 190° C. or lower in the water-soluble organic solvent in the ink of the present disclosure may be 100% by mass or less.

[0552] When the ink contains a water-soluble organic solvent (S-1), the content of the water-soluble organic solvent (S-1) is preferably 1% by mass to 35% by mass, more preferably 5% by mass to 30% by mass, further preferably 8% by mass to 15% by mass, and further preferably 10% by mass to 20% by mass, relative to the total amount of the ink.

[0553] (Organic solvents with boiling points exceeding 190°C)

[0554] The water-soluble organic solvent in the ink of the present disclosure may contain at least one water-soluble organic solvent having a boiling point exceeding 190°C.

[0555] Examples of the water-soluble organic solvent having a boiling point exceeding 190° C. include 2-methyl-1,3-propanediol (MPdiol) (boiling point 214° C.), ethylene glycol (boiling point 196° C.), 1,2-butanediol (boiling point 193° C.), glycerol (boiling point 290° C.), 1,2-hexanediol (boiling point 223° C.), 1,3-propanediol (boiling point 213° C.), diethylene glycol (boiling point 245° C.), diethylene glycol monobutyl ether (boiling point 230° C.), triethylene glycol (boiling point 285° C.), dipropylene glycol (boiling point 232° C.), tripropylene glycol (boiling point 267° C.), trimethylolpropane (boiling point 295° C.), 2-pyrrolidone (boiling point 245° C.), tripropylene glycol monomethyl ether (boiling point 243° C.), and triethylene glycol monomethyl ether (boiling point 248° C.).

[0556] <Color>

[0557] The ink in the present disclosure may be an ink containing at least one colorant (so-called “colored ink”) or an ink containing no colorant (so-called “transparent ink”).

[0558] When the ink contains a colorant, the colorant is preferably contained outside the specific particles (that is, the specific particles do not contain a colorant).

[0559] The colorant is not particularly limited and can be arbitrarily selected from known colorants such as pigments, water-soluble dyes, and disperse dyes. Among them, it is more preferable to include a pigment from the viewpoint of excellent weather resistance and rich color reproducibility.

[0560] The pigment is not particularly limited and can be appropriately selected according to the purpose, and for example, known organic pigments and inorganic pigments can be cited. In addition, the pigment can also include resin particles dyed with dyes, commercially available pigment dispersions, and surface-treated pigments (for example, a substance obtained by dispersing a pigment as a dispersion medium in water, a liquid compound, an insoluble resin, etc., and a substance after the pigment surface is treated with a resin, a pigment derivative, etc.).

[0561] Examples of the organic pigment and the inorganic pigment include yellow pigments, red pigments, magenta pigments, blue pigments, cyan pigments, green pigments, orange pigments, violet pigments, brown pigments, black pigments, and white pigments.

[0562] When a pigment is used as a colorant, a pigment dispersant may be used as necessary.

[0563] When a pigment is used as a colorant, a self-dispersible pigment having a hydrophilic group on the surface of the pigment particles can be used as the pigment.

[0564] Regarding the colorant and the pigment dispersant, reference may be made as appropriate to paragraphs 0180 to 0200 of JP-A-2014-040529 and paragraphs 0122 to 0129 of WO 2016 / 052053.

[0565] When the ink in the present disclosure contains a colorant, the content of the colorant is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and particularly preferably 0.5 to 5% by mass, based on the total amount of the ink.

[0566] <Other ingredients>

[0567] The ink in the present disclosure may contain other components in addition to the components described above, as necessary.

[0568] Other components may or may not be contained in specific particles.

[0569] The ink in the present disclosure may contain a surfactant, a polymerization inhibitor, an ultraviolet absorber, and the like as components that may or may not be contained in the specific particles.

[0570] Furthermore, the ink in the present disclosure may contain a water-soluble polymerizable monomer, a water-soluble photopolymerization initiator, a water-soluble resin, and the like on the outside of specific particles as necessary.

[0571] Regarding these components, for example, paragraphs 0134 to 0157 of International Publication No. 2016 / 052053 can be referred to.

[0572] <Preferred method for producing ink>

[0573] The method for producing the ink in the present disclosure is not particularly limited, but is preferably a method including the following steps:

[0574] A step of producing an aqueous dispersion of specific particles by the above-mentioned method for producing an aqueous dispersion (Production Method A or Production Method B); and

[0575] A step of adding and mixing other components such as a pigment and a water-soluble organic solvent to a water dispersion of specific particles.

[0576] In addition, as another method for producing the ink of the present disclosure, there can be mentioned a method of directly producing the ink as an aqueous dispersion of specific particles by using the above-mentioned method for producing an aqueous dispersion (production method A or production method B) to produce an aqueous dispersion of specific particles (i.e., a method without adding other components to the aqueous dispersion of specific particles).

[0577] <Preferred Physical Properties of Ink>

[0578] The viscosity of the ink in the present disclosure is preferably 3 mPa·s to 15 mPa·s, more preferably 3 mPa·s to 13 mPa·s, when the ink is set at 25°C to 50°C. In particular, the viscosity of the ink in the present disclosure is preferably 50 mPa·s or less when the ink is set at 25°C. When the viscosity of the ink is within the above range, higher ejection stability can be achieved.

[0579] In addition, the viscosity of the ink is a value measured using a viscometer.

[0580] As the viscometer, for example, VISCOMETER TV-22 (Toki Sangyo Co., Ltd.) can be used.

[0581] [Example]

[0582] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples.

[0583] Hereinafter, "parts" means parts by mass unless otherwise specified.

[0584] [Preparation of polymer P]

[0585] Polymers P1 to P4 are prepared as the polymers P contained in the specific particles.

[0586] The details are shown below.

[0587] <Preparation of polymer P1>

[0588] In a three-necked flask add:

[0589] 2,2-dimethylolpropionic acid (DMPA) (10.79 g) as a compound for introducing a hydrophilic group,

[0590] HMDI (61.84 g) as an isocyanate compound,

[0591] Compound (24) (16.57 g) and compound (38) (29.14 g) as diol compounds,

[0592] 2-tert-butyl-1,4-benzoquinone (0.003 g) as a polymerization inhibitor, and

[0593] Ethyl acetate (74.89 g) was added as an organic solvent and heated to 70°C.

[0594] 0.178 g of NEOSTANN U-600 (manufactured by Nitto Kasei Co., Ltd., an inorganic bismuth catalyst; hereinafter also referred to as "U-600") was added thereto, and the mixture was stirred at 70°C for 7 hours.

[0595] Next, ethyl acetate (114.39 g) and isopropyl alcohol (82.84 g) were added thereto, and the mixture was stirred at 70° C. for 3 hours. After stirring for 3 hours, the temperature was lowered to 50° C., diisopropylethylamine (9.36 g) was added, and the mixture was stirred for 1 hour. The reaction solution was naturally cooled to room temperature, and the concentration was adjusted with ethyl acetate, thereby obtaining a 30% by mass solution of polymer P1 (the solvent was a mixed solution of ethyl acetate / isopropyl alcohol).

[0596] The Mw of polymer P1 was 12,000 and the acid value was 0.68 mmol / g.

[0597] <Preparation of polymer P2>

[0598] In a three-necked flask add:

[0599] 2,2-dimethylolpropionic acid (DMPA) (10.94 g) as a compound for introducing a hydrophilic group,

[0600] IPDI (58.22 g) as an isocyanate compound,

[0601] Compound (24) (21.04 g) and compound (38) (29.65 g) as diol compounds,

[0602] 2-tert-butyl-1,4-benzoquinone (0.003 g) as a polymerization inhibitor, and

[0603] Methyl ethyl ketone (77.91 g) was added as an organic solvent and heated to 70°C.

[0604] 0.180 g of U-600 was added thereto, and the mixture was stirred at 70°C for 7 hours.

[0605] Then, methyl ethyl ketone (117.86 g) and isopropyl alcohol (83.90 g) were added thereto, and the mixture was stirred at 70° C. for 3 hours. After stirring for 3 hours, the mixture was cooled to 50° C., and diisopropylethylamine (10.02 g) was added thereto, followed by stirring for 1 hour. The reaction solution was naturally cooled to room temperature, and the concentration was adjusted with methyl ethyl ketone, thereby obtaining a 30% by mass solution of polymer P2 (the solvent was a mixed solution of methyl ethyl ketone / isopropyl alcohol).

[0606] The Mw of polymer P2 was 12,000 and the acid value was 0.68 mmol / g.

[0607] <Preparation of polymer P3>

[0608] In a three-necked flask add:

[0609] 2,2-dimethylolpropionic acid (DMPA) (10.72 g) as a compound for introducing a hydrophilic group,

[0610] IPDI (37.26 g) as an isocyanate compound,

[0611] Compound (18) (manufactured by Asahi Kasei Corporation, DURANOL T5652) (40.39 g) and compound (38) (29.03 g) as diol compounds,

[0612] 2-tert-butyl-1,4-benzoquinone (0.003 g) as a polymerization inhibitor, and

[0613] Methyl ethyl ketone (76.27 g) was added as an organic solvent and heated to 70°C.

[0614] 0.176 g of U-600 was added thereto, and the mixture was stirred at 70°C for 7 hours.

[0615] Then, methyl ethyl ketone (115.49 g) and isopropyl alcohol (82.18 g) were added thereto, and the mixture was stirred at 70° C. for 3 hours. After stirring for 3 hours, the mixture was cooled to 50° C., and diisopropylethylamine (9.81 g) was added thereto, and the mixture was stirred for 1 hour. The reaction solution was naturally cooled to room temperature, and the concentration was adjusted with methyl ethyl ketone, thereby obtaining a 30% by mass solution of polymer P3 (the solvent was a mixed solution of methyl ethyl ketone / isopropyl alcohol).

[0616] The Mw of polymer P3 was 12,000 and the acid value was 0.68 mmol / g.

[0617] <Preparation of polymer P4>

[0618] In a three-necked flask add:

[0619] 2,2-dimethylolpropionic acid (DMPA) (11.06 g) as a compound for introducing a hydrophilic group,

[0620] IPDI (39.59 g) as an isocyanate compound,

[0621] Compound (18) (manufactured by Asahi Kasei Corporation, DURANOL T5652) (24.79 g), compound (38) (29.97 g), and Silaplane FM-DA11 (manufactured by JNC Corporation; diol compound containing a polysiloxane bond) (15.76 g) as diol compounds,

[0622] 2-tert-butyl-1,4-benzoquinone (0.003 g) as a polymerization inhibitor, and

[0623] Methyl ethyl ketone (78.78 g) was added as an organic solvent and heated to 70°C.

[0624] 0.182 g of U-600 was added thereto, and the mixture was stirred at 70°C for 7 hours.

[0625] Then, methyl ethyl ketone (119.13 g) and isopropyl alcohol (84.82 g) were added thereto, and the mixture was stirred at 70° C. for 3 hours. After stirring for 3 hours, the mixture was cooled to 50° C., and diisopropylethylamine (10.12 g) was added thereto, and the mixture was stirred for 1 hour. The reaction solution was naturally cooled to room temperature, and the concentration was adjusted with methyl ethyl ketone, thereby obtaining a 30% by mass solution of polymer P4 (the solvent was a mixed solution of methyl ethyl ketone / isopropyl alcohol).

[0626] The Mw of polymer P4 was 12,000 and the acid value was 0.68 mmol / g.

[0627] [Example 1]

[0628] <Preparation of Aqueous Dispersion of Specific Particles>

[0629] -Preparation of oil phase components-

[0630] A 30 mass % solution (66.7 g) of polymer P1,

[0631] SR295 (21.5 g) as the polymerizable monomer M,

[0632] IRGACURE (registered trademark) 819 (1.5 g) as a photopolymerization initiator,

[0633] ITX (isopropylthioxanthone) (0.25 g) as a sensitizer, and

[0634] Ethyl acetate (36.7 g) was added, and the mixture was stirred at room temperature for 30 minutes to obtain an oil phase component.

[0635] SR295 is a tetrafunctional free radical polymerizable monomer, specifically, pentaerythritol tetraacrylate (molecular weight 352). SR295 is classified as a monomer (M-1), and among monomers (M-1), it is classified as a monomer (M1B) (i.e., a monomer (M-1) other than monomer (M1A)) (see Table 1).

[0636] IRGACURE (registered trademark) 819 is an acylphosphine oxide-based radical polymerization initiator, and specifically, it is bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0637] -Preparation of aqueous phase components-

[0638] As an aqueous phase component, distilled water (140 g) was prepared.

[0639] - Preparation of aqueous dispersion of specific particles -

[0640] The oil phase component and the water phase component were mixed, and the resulting mixture was emulsified at room temperature for 30 minutes at 7000 rpm (revolution per minute) using a homogenizer to obtain an emulsion.

[0641] The obtained emulsion was added to distilled water (60 g), and the obtained liquid was heated to 50° C. and stirred at 50° C. for 5 hours to distill off the solvent (ethyl acetate and isopropyl alcohol in Example 1) from the liquid.

[0642] The liquid obtained by distilling off the solvent was diluted with distilled water so that the total solid content became 20% by mass, thereby obtaining an aqueous dispersion of specific particles.

[0643] The volume average dispersed particle size of the specific particles is 70 nm.

[0644] <Preparation of ink>

[0645] The components of the following composition were mixed to prepare ink.

[0646] -Ink composition-

[0647] · Aqueous dispersion of the above-mentioned specific particles (total solid content of the specific particles: 20% by mass)

[0648] …50 servings

[0649] Pigment dispersion (Pro-jet Cyan APD1000 (manufactured by FUJIFILM Imaging Colorants Co., Ltd.), pigment concentration 14% by mass)

[0650] …15 servings

[0651] Fluorine-based surfactant (manufactured by DuPont, Capstone FS-31, solid content 25% by mass)

[0652] …0.3 serving

[0653] Propylene glycol (PG)

[0654] …15 servings

[0655] ·water

[0656] ...total of 100 copies

[0657] The total solid content of the specific particles in the ink (ie, the ink before ejection) is 10% by mass. In the present example, this value is regarded as the total solid content of the specific particles in the ink at the time of landing (see Table 1).

[0658] <Image Record>

[0659] The ink cartridge attached to an inkjet recording apparatus (product name "DMP-2850", manufactured by Fujifilm Corporation) was filled with the above ink, and an image was recorded on a PVC (polyvinyl chloride) film as a substrate in the following manner.

[0660] As a PVC film (substrate), "AVERY (registered trademark) 400 GLOSSWHITE PERMANENT" manufactured by Avery Dennison was used.

[0661] The substrate is heated to a temperature of 50° C. on the side to which the ink is applied (i.e., the side on which the ink lands) (preheating step). This preheating is performed using a platen heater, which is provided upstream of the inkjet head in the substrate conveying direction in the DMP-2850.

[0662] The ink is ejected from the inkjet head of the inkjet recording device onto the heated substrate (imparting process). The ink ejection conditions are set to 900 dpi (dots per inch) and 10 pL per dot. The ink is applied while the substrate is heated, so that the ink lands on the surface of the substrate maintained at 50°C. The substrate is heated during the ink application using a platen heater, which is provided below the inkjet head in the DMP-2850 (i.e., the ink application area).

[0663] The ink applied on the substrate was irradiated (i.e., exposed) with UV light (peak wavelength 395 nm) from a 395 nm LED lamp (product name "PEL UV CURE UNIT", manufactured by PRINTEDELECTRONICS) arranged near the inkjet head (irradiation step). The irradiation energy of the UV light was set to 1000 mJ / cm 2 .

[0664] The time from ink landing to exposure (that is, the time from the moment the ink landed on the substrate to the start of UV light irradiation) was adjusted to 0.10 seconds (see Table 1).

[0665] Next, the exposed ink was dried by heating at 50° C. for 180 seconds to obtain an image (drying step). The ink was dried by heating the substrate by bringing the surface opposite to the ink application surface into contact with a heating plate.

[0666] <Measurement and Evaluation>

[0667] The following measurements and evaluations were performed using the ink obtained above.

[0668] The results are shown in Tables 1 and 2.

[0669] (Total solid content of specific particles in ink at the time of exposure start)

[0670] The total solid content (mass %) of the specific particles in the ink at the start of exposure was determined by the above-mentioned method using an FTA-1000 contact angle meter and a warm water circulation temperature control stage manufactured by FTA Corporation.

[0671] (Liquid component remaining)

[0672] The residual amount (mass %) of the liquid component in the irradiation step (i.e., the content of the liquid component in the ink after irradiation with active energy rays relative to the content (mass %) of the liquid component in the ink before irradiation with active energy rays) is determined by the above method.

[0673] The residual amount (mass %) of the liquid component in the drying process (i.e., the content of the liquid component in the ink after heat drying relative to the content (mass %) of the liquid component in the ink before heat drying in the drying process) is determined by the above method.

[0674] (Image quality)

[0675] Using the ink stored at room temperature within 1 day after preparation, the images were recorded at 5, 6, and 7 points under the above-mentioned image recording conditions. Figure 1 Text image shown.

[0676] The character images of each size were observed with a 10-fold magnifying glass (manufactured by ETSUMI Co., Ltd.). Based on the observation results, the clarity of the image was evaluated according to the following evaluation criteria. In the following evaluation criteria, the image quality was rated A.

[0677] -Image quality evaluation criteria-

[0678] A: 5 point size Figure 1 The text image shown has no deformation or color bleeding after formation.

[0679] B: 6 o'clock size Figure 1 The text image shown has no deformation or bleeding after formation (except for the case corresponding to A).

[0680] C: 7 o'clock size Figure 1 The text image shown has no deformation or bleeding after formation (except for the cases corresponding to A and B).

[0681] D: 7 o'clock size Figure 1 The text image shown is deformed or bleeds after formation.

[0682] (Abrasion resistance (dry))

[0683] Using the ink stored at room temperature within 1 day after preparation, a solid image was recorded on a substrate (PVC film) under the above-mentioned image recording conditions.

[0684] The solid image formed on the substrate was subjected to a friction test under the following conditions. A dried canvas was used as the canvas.

[0685] Test equipment: Cardboard abrasion tester (JIS P-8136) Japan TMC Co., Ltd.

[0686] Canvas type: Canvas No. 6 (manufactured by Takeya Co., Ltd.)

[0687] Friction times: 500 times

[0688] Load: 500gf

[0689] The density of cyan transferred to the canvas after the friction test (hereinafter referred to as "transfer OD") was measured using a spectrophotometer CM-25cG (manufactured by Konica Minolta), and the abrasion resistance (drying) of the solid image was evaluated according to the following evaluation criteria. In the following evaluation criteria, the image with the best abrasion resistance (drying) was rated A.

[0690] -Evaluation criteria for wear resistance (dry)-

[0691] A: The transfer OD is 0 or more and less than 0.03.

[0692] B: Transfer OD is 0.03 or more and less than 0.1.

[0693] C: Transfer OD is 0.1 or more and less than 0.2.

[0694] D: Transfer OD is 0.2 or more.

[0695] (Abrasion resistance (water))

[0696] The same evaluation as that of the abrasion resistance (dry) was performed except that a canvas moistened with water was used instead of the dry canvas.

[0697] (Abrasion resistance (IPA))

[0698] The same evaluation as that for the abrasion resistance (dry) was performed except that a canvas moistened with isopropyl alcohol (IPA) was used instead of the dry canvas.

[0699] (Image adhesion)

[0700] According to the above-mentioned image recording operation, a solid image of a square of 5 cm×5 cm was recorded on the substrate to obtain a recorded object.

[0701] A PVC film of A6 size (hereinafter referred to as "PVC film 2") was placed on the image recording surface of the obtained recorded material. A 300 g / cm 2 The film was kept at 40° C. for 24 hours under a load of 1.5° C. As the PVC film 2, the same film as the PVC film as the base material was used.

[0702] After 24 hours, the recorded material and the PVC film 2 were separated, and the solid image on the recorded material was visually observed. The blocking resistance of the image was evaluated according to the following evaluation criteria.

[0703] In the following evaluation criteria, the level in which the sticking of the image was most suppressed was "A".

[0704] -Evaluation criteria for image adhesion-

[0705] A: No peeling of the image or decrease in density was visually observed.

[0706] B: A decrease in density was visually observed in at least a portion of the image, but no peeling of the image was visually observed.

[0707] C: Image peeling was visually observed, but the peeling area exceeded the area of ​​the image recorded initially (25 cm 2 ) is 0% and less than 5%.

[0708] D: Image peeling was visually observed, and the peeling area was the same as the area of ​​the image recorded initially (25 cm 2 ) more than 5%.

[0709] (Image Adhesion)

[0710] Using the ink stored at room temperature within 1 day after preparation, a solid image was recorded on a substrate (PVC film) under the above-mentioned image recording conditions.

[0711] The obtained solid image was subjected to a cross-cut test in accordance with ISO 2409 (2013) (cross-cut method), and the adhesion of the solid image to the substrate was evaluated according to the following evaluation criteria.

[0712] In the cross-hatch test, the cutting interval was set to 1 mm, and a grid of 25 squares of 1 mm square was formed.

[0713] In the following evaluation criteria, the level A was the most excellent in adhesion of the solid image.

[0714] In the following evaluation criteria, the ratio (%) of mesh peeling is a value obtained by the following formula: The total number of meshes in the following formula is 25.

[0715] The ratio of mesh peeling (%) = [(the number of meshes peeling) / (the total number of meshes)] × 100

[0716] -Evaluation criteria for image adhesion-

[0717] A: The ratio (%) of grid peeling is 0% or more and 5% or less.

[0718] B: The ratio (%) of grid peeling is more than 5% and 15% or less.

[0719] C: The ratio (%) of grid peeling is more than 15% and 35% or less.

[0720] D: The ratio (%) of grid peeling exceeds 35%.

[0721] (Ink jetting properties)

[0722] The ink prepared and stored at room temperature within one day was ejected from the inkjet head of the inkjet recording apparatus for 30 minutes, and then the ejection was stopped.

[0723] After 5 minutes had passed since the ejection was stopped, the ink was ejected from the head onto the substrate again to form a solid image of 5 cm×5 cm.

[0724] These images were visually observed to confirm the presence or absence of dot missing due to non-ejecting nozzles, and the ejection properties of the ink were evaluated according to the following evaluation criteria.

[0725] In the following evaluation criteria, A was the most excellent in ink ejection properties.

[0726] -Evaluation criteria for spitting properties-

[0727] A: Dot missing due to nozzle failure or the like was not observed, and a good image was obtained.

[0728] B: Dot missing due to a non-ejecting nozzle or the like was slightly observed, but it was not a problem in practical use.

[0729] C: Dot missing occurs due to nozzle failure, etc., and the image is not suitable for practical use.

[0730] D: Cannot be sprayed out from the nozzle.

[0731] [Examples 2 to 4]

[0732] In the preparation of the aqueous dispersion of specific particles, the same operations as in Example 1 were performed except that the 30 mass% solution (66.7 g) of polymer P1 was changed to a 30 mass% solution (66.7 g) of polymer P2, a 30 mass% solution (66.7 g) of polymer P3, and a 30 mass% solution (66.7 g) of polymer P4, and the polymer P1 in the specific particles was changed to each of polymers P2 to P4.

[0733] The results are shown in Tables 1 and 2.

[0734] [Examples 5 and 18 to 20, and Comparative Example 1]

[0735] The same operation as in Example 1 was carried out except that the type of the polymerizable monomer M was changed as shown in Table 1.

[0736] In Examples 18 to 20, two types of polymerizable monomers M were used in the contents shown in Table 1.

[0737] In Comparative Example 1, a monomer (M-2) (ie, a polymerizable monomer M other than the monomer (M-1)) was used.

[0738] The results are shown in Tables 1 and 2.

[0739] [Examples 6, 7, 12 and 13]

[0740] The same operation as in Example 5 was performed except that the temperature of the substrate when each ink landed and the temperature of the substrate when the ink was applied were changed to the temperatures shown in the column “Temperature of the substrate when the ink landed” in Table 1.

[0741] The results are shown in Tables 1 and 2.

[0742] [Examples 8 and 9, and Comparative Example 4]

[0743] The same operation as in Example 5 was performed except that the time from ink landing to the start of exposure was changed as shown in Table 1.

[0744] The results are shown in Tables 1 and 2.

[0745] [Examples 10 and 11, and Comparative Examples 2 and 3]

[0746] The same operation as in Example 5 was carried out except that the contents of the polymerizable monomers M and the polymers P were changed as shown in Table 1 without changing the total amount of the polymerizable monomers M and the polymers P.

[0747] The results are shown in Tables 1 and 2.

[0748] [Example 14]

[0749] The same operation as in Example 5 was performed except that the temperature of the substrate when each ink landed and the temperature of the substrate when the ink was applied were changed to the temperatures shown in the "Temperature of the substrate when the ink landed" column in Table 1, and the time from the landing of the ink to the start of exposure was changed as shown in Table 1.

[0750] The results are shown in Tables 1 and 2.

[0751] [Examples 15 and 16]

[0752] The same operation as in Example 5 was performed except that the temperature of the post-exposure heating and drying (hereinafter also referred to as the post-exposure heating temperature) was changed as shown in Table 1.

[0753] The results are shown in Tables 1 and 2.

[0754] [Example 17]

[0755] The same operation as in Example 16 was performed except that the time for heat drying after exposure was shortened and the amount of liquid component remaining in the drying step was changed as shown in Table 1.

[0756] The results are shown in Tables 1 and 2.

[0757] [Table 1-1]

[0758]

[0759] [Table 1-2]

[0760]

[0761] [Table 2]

[0762]

[0763] - Description of Table 1 -

[0764] As the components in the ink, only the polymer P and the polymerizable monomer M in the specific particles are shown, and the indication of other components in the ink is omitted.

[0765] The abbreviations of the polymerizable monomers M have the following meanings.

[0766] SR295: Pentaerythritol tetraacrylate. Made by Sartomer.

[0767] SR833S: Tricyclodecane dimethanol diacrylate. Made by Sartomer.

[0768] OTA480: Glyceryl propoxy triacrylate. Made by Daicel-Allnex.

[0769] CD595: 1,10-decanediol diacrylate. Made by Sartomer.

[0770] FA512M: dicyclopentenyloxyethyl methacrylate. Made by Hitachi Chemical Co., Ltd.

[0771] SR444: Pentaerythritol triacrylate. Made by Sartomer.

[0772] As shown in Table 1, in each embodiment,

[0773] Ink is applied to a substrate, and when the time from the landing of the ink to the start of exposure reaches less than 1.00 second, the ink applied to the substrate is irradiated with active energy rays to obtain an image, wherein the ink contains water and particles containing a polymer P and a polymerizable monomer M, the polymerizable monomer M contains a monomer (M-1) having a viscosity of less than 500 mPa·s at 25°C, and the content of the monomer (M-1) is 25% to 80% by mass relative to the total solid content of the particles.

[0774] According to each of the examples, an image with excellent image quality and abrasion resistance was obtained.

[0775] On the other hand, the results of the comparative examples are as follows.

[0776] In Comparative Example 1 in which the polymerizable monomer M did not include the monomer (M-1) but included the monomer (M-2) having a viscosity exceeding 500 mPa·s, the image quality and abrasion resistance were reduced.

[0777] In Comparative Example 2 in which the content of the monomer (M-1) was less than 25% by mass based on the total solid content of the particles, the image quality and abrasion resistance were also reduced.

[0778] In Comparative Example 3 in which the content of the monomer (M-1) exceeded 80% by mass based on the total solid content of the particles, the image quality and abrasion resistance were also reduced.

[0779] In Comparative Example 4, in which the time from ink landing to the start of exposure exceeded 1.00 second, the image quality was deteriorated.

[0780] From the results of Examples 1 and 5, it is understood that when the monomer (M-1) contains a monomer (M1A) having a viscosity of 150 mPa·s or less at 25° C. (Example 5), the image quality and abrasion resistance are further improved.

[0781] From the results of Examples 9 and 14, it is understood that the image quality and abrasion resistance of the image in Example 9, in which the content of the specific particles in the ink at the start of exposure was 3% by mass or more and less than 20% by mass, were further improved.

[0782] From the results of Examples 6, 7, 12 and 13, it is understood that when the temperature of the surface of the substrate on the ink landing side is 30° C. to 70° C. in the application step (Examples 7 and 12), the image quality is further improved.

[0783] From the results of Examples 5 and 15, it is understood that when a drying step of heating and drying the exposed ink is included (Example 5), the image quality and abrasion resistance are further improved.

[0784] From the results of Examples 16 and 17, it is understood that when the amount of the liquid component remaining in the drying step is 2.0% by mass or more (Example 17), the adhesion of the image to the substrate is further improved.

[0785] From the results of Examples 5 and 15, it is understood that when the amount of the liquid component remaining in the drying process is 50% by mass or less (Example 5), the image quality and abrasion resistance are further improved.

[0786] The entire disclosure of Japanese Patent Application No. 2020-163386 filed on September 29, 2020 is incorporated into this specification by reference.

[0787] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent application, and technical standard was specifically and individually described as being incorporated by reference.

Claims

1. An inkjet recording method, comprising: A step of preparing ink, wherein the ink contains water and particles including a polymer P and a polymerizable monomer M, wherein the polymer P is a chain polymer having a weight average molecular weight of 3,000 to 200,000, the polymerizable monomer M includes a monomer M-1 having a viscosity of 500 mPa·s or less at 25° C., the content of the monomer M-1 is 25% to 80% by mass relative to the total solid content of the particles, the monomer M-1 includes a monomer M1A having a viscosity of 10 mPa·s or more and 150 mPa·s or less at 25° C., the ratio of the monomer M1A to the total amount of the monomer M-1 is 50% to 100% by mass, and the polymer P is a urethane polymer, a urethane urea polymer, or a urea polymer; an imparting step of imparting the ink to a substrate by an inkjet method; as well as an irradiation step of irradiating the ink applied on the substrate with active energy rays, The time from the moment when the ink lands on the substrate to the start of irradiation with the active energy ray is 1.00 second or less, In the applying step, the temperature of the surface of the substrate on the ink landing side is 30°C to 70°C.

2. The inkjet recording method according to claim 1, wherein The total solid content of the particles in the ink at the time when the irradiation with the active energy rays starts is 3 mass % or more and less than 20 mass % based on the total amount of the ink at the time when the irradiation with the active energy rays starts.

3. The inkjet recording method according to claim 1 or claim 2, The inkjet recording method satisfies at least one of the following: Prior to the imparting step, a preheating step of heating the substrate is included; and In the applying step, the substrate is heated and the ink is applied.

4. The inkjet recording method according to claim 1 or claim 2, wherein: In the irradiation step, the irradiation energy of the active energy line is 300 mJ / cm 2 Above and 5J / cm 2 the following, The content of the liquid component in the ink after irradiation with the active energy ray is 10% by mass or more relative to the content of the liquid component in the ink before irradiation with the active energy ray.

5. The inkjet recording method according to claim 1 or claim 2, wherein: The method further includes a drying step of heating and drying the ink irradiated with the active energy rays.

6. The inkjet recording method according to claim 5, wherein In the drying step, the content of the liquid component in the ink after heat drying is 2.0% by mass to 50% by mass relative to the content of the liquid component in the ink before heat drying.

Images