Image recording method

Abstract

To provide an image recording method capable of simultaneously realizing an image density and scratch resistance of an image.SOLUTION: An image recording method includes: a first ink application process of applying an ink including a resin particle to a recording medium; a heat-desiccation process of heating and desiccating the recording medium with the ink applied; a heating and drying process of heating and compressing the heated and dried recording medium; and a second ink application process of further applying the ink to the heated and compressed recording medium. A relation T1<Te<T2 is satisfied when a melt temperature of the resin particle is Te[°C], a temperature of the recording medium heated and dried at the heating and drying process is T1[°C], and a temperature of the recording medium heated and compressed at the heating and drying process is T2[°C].SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image recording method. [Background technology]

[0002] In the inkjet recording method, an image is formed by applying an ink containing a coloring material onto a recording medium such as paper. It has been known that image quality and image fastness can be improved by subjecting an image formed with ink to a heat drying process or a heat and pressure process. Patent Document 1 discloses an image forming method for improving image density and blocking resistance by subjecting an image formed with ink containing carbon black to heat drying and heat and pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-131590 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the present inventors have found through their studies that it may be difficult to achieve both image density and abrasion resistance in the image forming method described in Patent Document 1. In particular, it has been found that it is difficult to achieve both image density and abrasion resistance in the image when lightly coated paper or uncoated paper is used.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an image recording method which is capable of achieving both high image density and high abrasion resistance of the image. [Means for solving the problem]

[0006] The above object can be achieved by the present invention described below.

[0007] That is, the image recording method according to the present invention includes: a first ink application step of applying ink containing resin particles to a recording medium; a heat drying step of heating and drying the recording medium to which the ink has been applied; a heat pressing step of heating and pressing the heat-dried recording medium; and a second ink application step of further applying the ink to the heat-pressed recording medium. When the melting temperature of the resin particles is Te [°C], the temperature of the recording medium heat-dried by the heat drying step is T1 [°C], and the temperature of the recording medium heat-pressed by the heat pressing step is T2 [°C], it is characterized by satisfying the relationship T1 < Te < T2.

Effect of the Invention

[0008] According to the present invention, it is possible to provide an image recording method capable of achieving both image density and image rub resistance.

Brief Description of the Drawings

[0009] [Figure 1] It is a schematic diagram showing the configuration of an image recording apparatus using the image recording method in one embodiment of the present invention. [Diagram 2] It is a schematic diagram showing the configuration of an image recording apparatus using the image recording method in one embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described in detail with reference to preferred embodiments. In the present invention, when the compound is a salt, although the salt dissociates into ions and exists in the ink, for convenience, it is expressed as "containing a salt". The "unit" regarding the resin refers to the smallest repeating unit constituting the resin, and refers to the structure formed by the (co)polymerization of one monomer. Also, physical property values are values at room temperature (25°C) unless otherwise specified.

[0011] The image recording method according to this embodiment includes a first ink application step of applying ink containing resin particles to a recording medium, a heating and drying step of heating and drying the recording medium to which the ink has been applied, a heating and pressing step of heating and pressing the heated and dried recording medium, and a second ink application step of further applying the ink to the heated and pressed recording medium. When the melting temperature of the resin particles is Te [°C], the temperature of the recording medium dried by the heating and drying step is T1 [°C], and the temperature of the recording medium heated and pressed by the heating and pressing step is T2 [°C], the relationship T1 < Te < T2 is satisfied.

[0012] By the heating and drying step, evaporation of a solvent such as an aqueous medium contained in the ink on the recording medium can be promoted without melting the resin particles. As a result, in the heating and pressing step, which is a step after the heating and drying step, the thermal energy applied by the heating and pressing device is less likely to be consumed by the evaporation of the solvent in the ink, so that the resin particles in the ink can be efficiently melted. As a result, the adhesion between the ink film and the recording medium and the strength of the ink film itself are increased, and the scratch resistance of the image can be improved. Further, ink is further applied to the ink film formed on the recording medium in the second ink application step. Therefore, even for a recording medium such as fine coated paper or uncoated paper that absorbs ink more easily than ordinary coated paper, the coloring material in the ink is less likely to be taken into the recording medium and is likely to exist on the surface of the recording medium, so that the image density can also be improved. As a result, it has become possible to achieve both high image density and high scratch resistance of the image.

[0013] [Image Recording Method] Hereinafter, with reference to the drawings, an image recording method according to an embodiment of the present invention will be described.

[0014] Fig. 1 is a schematic diagram showing the configuration of an image recording apparatus using an image recording method according to one embodiment of the present invention. The image recording apparatus 100 shown in Fig. 1 includes a conveying device 105 which is a conveying means for conveying a sheet of recording medium 101 in the direction of the arrow, an ink applying device 102 which is an ink applying means for applying ink onto the recording medium, a heating and drying device 103 which is a heating and drying means for heating and drying the recording medium 101 to which the ink has been applied, and a heating and pressing device 104 which is a heating and pressing means for heating and pressing the heated and dried recording medium.

[0015] First, image data is transmitted from an image data supply device (not shown) to the image recording device 100, and the image recording device 100 is instructed to record an image on a recording medium.

[0016] Then, the conveying device 105 starts conveying the recording medium 101 in the direction of the arrow. In Fig. 1, the recording medium conveying device 105 is equipped with a belt, and the recording medium 101 is conveyed by this belt, but the conveying device 105 is not limited to this, and a known conveying device such as a conveying device using a paper feed cylinder can be used.

[0017] There is no particular limitation on the recording medium 101 as long as it is capable of recording an image with ink, but the recording medium is preferably uncoated paper or lightly coated paper. 1 / 2 The above recording medium is preferable. The pure water absorption coefficient of the recording medium can be measured by an automatic scanning absorptiometer. As the automatic scanning absorptiometer, KM500win (product number: No. 2071) manufactured by Kumagai Riki Kogyo Co., Ltd. can be used.

[0018] Then, ink is applied to the surface of the recording medium 101 using an ink application device 102. The ink application device 102 is not particularly limited as long as it can apply ink to the recording medium 101, but is preferably an inkjet recording head. The inkjet recording head has nozzles that eject ink toward the recording medium 101. In terms of printing speed, the inkjet recording head is preferably a full line head type inkjet recording head in which nozzles are extended in the width direction of the recording medium. In addition, when applying ink of multiple colors to the recording medium, the multiple colors may be applied by one inkjet recording head, or the image recording device may be provided with an inkjet recording head for each color, and each color ink may be applied from each inkjet recording head.

[0019] In the first ink application step of applying ink to the recording medium 101, the amount of ink applied onto the recording medium 101 is a portion of the amount of ink required to record a predetermined image. The amount of ink applied in this first ink application step is preferably 50% by mass or more and 90% by mass or less based on the total mass of ink finally applied to the recording medium (the total amount of ink applied in the first ink application step and the second ink application step). By having the amount of ink applied in the first ink application step within the above range, it is possible to further improve the scratch resistance of the image in the heating and pressing step described below.

[0020] Next, in the heat drying process, the recording medium 101 to which the ink has been applied is heated and dried by the heat drying device 103. The temperature T1 [°C] of the recording medium heated and dried in this heat drying process is lower than the melting temperature Te [°C] of the resin particles contained in the ink. Therefore, in this heat drying process, the resin particles in the ink are not melted. On the other hand, the evaporation of the solvent, such as the aqueous medium, contained in the ink is promoted. There is no particular limitation on the heat drying device, and known heat drying devices such as hot air heaters and infrared heaters can be used. In addition, it is preferable that the heat drying device is a non-contact type heat drying device that does not come into contact with the recording medium. There is also no particular limitation on the heat drying time, but it is preferable that it is 1 second or more and 10 minutes or less.

[0021] In the heating and pressurizing process, the recording medium that has been heated and dried in the heating and drying process is heated and pressurized by the heating and pressurizing device 104. The temperature T2 [°C] of the recording medium heated and pressurized in this heating and pressurizing process is higher than the melting temperature Te [°C] of the resin particles contained in the ink. Therefore, in this heating and pressurizing process, the resin particles in the ink are melted, and the strength of the ink film itself formed by the melting of the resin particles and the adhesive force between the ink film and the recording medium are improved. In addition, the surface shape of the ink film is smoothed, so that the friction of the surface of the image (ink film) is reduced. As a result, the scratch resistance of the image is improved. On the other hand, the image density may be reduced due to the influence of the minute surface shape of the ink film on the recording medium.

[0022] The heating and pressing device is not particularly limited, and a known heating and pressing device having a heating roller, a heating belt, or the like as a heating and pressing member can be used. In addition, the heating and pressing device is preferably a contact type heating and pressing device that comes into contact with the recording medium. The surface material of the heating and pressing member is preferably a material with low surface free energy such as silicone rubber, fluororubber, PTFE, PFA, etc. By using a material with low surface free energy as the surface material of the heating and pressing member, it is possible to make it difficult for ink to adhere from the recording medium to the surface of the heating and pressing member. In addition, the surface of the heating and pressing member is preferably smooth.

[0023] In the second ink application process, ink is applied to the recording medium that has been heated and pressurized in the heating and pressurizing process. In this second ink application process, the amount of ink applied to the recording medium 101 is the amount obtained by subtracting the amount of ink applied in the first ink application process from the amount of ink required to record a predetermined image. The amount of ink applied in this second ink application process is preferably 10% by mass or more and 50% by mass or less based on the total mass of ink finally applied to the recording medium. By setting the amount of ink applied in the second ink application process within the above range, the image density can be further improved. In addition, it is preferable that the ink applied in the second ink application process is applied so as to overlap the ink applied to the recording medium in the first ink application process.

[0024] The ink application in the second ink application step may be performed by the ink application device 102 used in the first ink application step, or the image recording apparatus 100 may further include an ink application device (second ink application device) different from the ink application device 102 (first ink application device), and the ink application may be performed by this second ink application device. In the image recording apparatus 100 shown in Fig. 1, after the recording medium 101 is subjected to a heating and pressurizing treatment, the recording medium is transported by a recording medium transport device 105b so that the ink is applied by the ink application device 102 used in the first ink application step.

[0025] The recording medium to which the ink has been applied in the second ink application step is preferably heated and dried again by the heating and drying device 103. The heating temperature of the recording medium by this heating and drying device 103 is preferably equal to or lower than the melting temperature of the resin particles in the ink. In addition, it is preferable that the heated and dried recording medium is not heated and pressurized by the heating and pressurizing device 104. When heating and pressurizing is not performed, the heating and pressurizing device 104 is separated from the conveying means 105, and the recording medium 101 is discharged.

[0026] When the processing of the image data transmitted from the image supply device is completed in this manner, the main image recording is completed.

[0027] [ink] Each component of the ink that can be used in this embodiment will be described.

[0028] (Colorant) The coloring material contained in the ink may be a pigment or a dye, and the content of the coloring material in the ink is preferably from 0.5% to 15.0% by mass, and more preferably from 1.0% to 10.0% by mass, based on the total mass of the ink.

[0029] The type of pigment that can be used as a coloring material is not particularly limited. Specific examples of pigments include inorganic pigments such as carbon black and titanium oxide; and organic pigments such as azo, phthalocyanine, quinacridone, isoindolinone, imidazolone, diketopyrrolopyrrole, and dioxazine. These pigments can be used alone or in combination as needed.

[0030] The pigment dispersion method is not particularly limited. For example, a resin-dispersed pigment dispersed with a resin dispersant, or a self-dispersed pigment in which a hydrophilic group such as an anionic group is bonded directly or via another atomic group to the surface of the pigment particles can be used. Of course, pigments with different dispersion methods can be used in combination.

[0031] As the resin dispersant for dispersing the pigment, a known resin dispersant used in inkjet inks can be used. In particular, in this embodiment, it is preferable to use an acrylic water-soluble resin dispersant having both a hydrophilic unit and a hydrophobic unit in the molecular chain. Examples of the resin form include block copolymers, random copolymers, graft copolymers, and combinations thereof.

[0032] The resin dispersant in the ink may be in a state of being dissolved in the liquid medium, or in a state of being dispersed as resin particles in the liquid medium. In the present invention, the term "water-soluble resin" means that when the resin is neutralized with an alkali equivalent to its acid value, it does not form particles whose particle size can be measured by a dynamic light scattering method.

[0033] The hydrophilic unit (a unit having a hydrophilic group such as an anionic group) can be formed, for example, by polymerizing a monomer having a hydrophilic group. Specific examples of the monomer having a hydrophilic group include acidic monomers having an anionic group such as (meth)acrylic acid and maleic acid, and anionic monomers such as anhydrides and salts of these acidic monomers. Examples of cations constituting the salts of acidic monomers include ions of lithium, sodium, potassium, ammonium, and organic ammonium.

[0034] The hydrophobic unit (a unit not having hydrophilicity such as an anionic group) can be formed, for example, by polymerizing a monomer having a hydrophobic group. Specific examples of the monomer having a hydrophobic group include monomers having an aromatic ring such as styrene, α-methylstyrene, and benzyl (meth)acrylate; and monomers having an aliphatic group such as ethyl (meth)acrylate, methyl (meth)acrylate, and butyl (meth)acrylate (i.e., (meth)acrylic ester monomers).

[0035] The acid value of the resin dispersant is preferably 50 mgKOH / g or more and 550 mgKOH / g or less, more preferably 100 mgKOH / g or more and 250 mgKOH / g or less. The weight average molecular weight of the resin dispersant is preferably 1,000 or more and 50,000 or less. The pigment content (mass%) is preferably 0.3 times or more and 10.0 times or less in terms of the mass ratio to the resin dispersant content (pigment / resin dispersant).

[0036] As the self-dispersing pigment, a pigment having an anionic group such as a carboxylic acid group, a sulfonic acid group, or a phosphonic acid group bonded directly or via another atomic group (-R-) to the particle surface of the pigment can be used. The anionic group may be either an acid type or a salt type, and when it is a salt type, it may be either a partially dissociated state or a completely dissociated state. Examples of the cation serving as a counter ion when the anionic group is a salt type include an alkali metal cation, ammonium, and organic ammonium. Specific examples of the other atomic group (-R-) include a linear or branched alkylene group having 1 to 12 carbon atoms, an arylene group such as a phenylene group or a naphthylene group, an amide group, a sulfonyl group, an amino group, a carbonyl group, an ester group, and an ether group. A group consisting of a combination of these groups may also be used.

[0037] The type of dye that can be used as a coloring material is not particularly limited, but it is preferable to use a dye having an anionic group. Specific examples of the dye include azo-based, triphenylmethane-based, (aza)phthalocyanine-based, xanthene-based, and anthrapyridone-based dyes. These dyes can be used alone or in combination as needed.

[0038] In this embodiment, it is also preferable to use a so-called self-dispersing pigment, which is made dispersible by modifying the surface of the pigment itself without using a dispersant.

[0039] (Resin particles) The ink contains resin particles. The material of the resin particles is not particularly limited, and known resins can be used as appropriate. Specifically, resin particles made of various materials such as olefin-based, polystyrene-based, urethane-based, and acrylic-based materials can be used. The weight-average molecular weight (Mw) of the resin particles is preferably in the range of 1,000 to 2,000,000. The volume-average particle diameter of the resin particles measured by dynamic light scattering is preferably 10 nm to 1,000 nm, more preferably 100 nm to 500 nm. The content (mass%) of the resin particles in the ink is preferably 1.0 mass% to 50.0 mass%, more preferably 2.0 mass% to 40.0 mass%, based on the total mass of the ink.

[0040] (aqueous medium) The ink may contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. As the water, deionized water or ion-exchanged water is preferably used. The content (mass%) of water in the ink is preferably 50.0% by mass or more and 95.0% by mass or less based on the total mass of the ink. The content (mass%) of water-soluble organic solvent in the ink is preferably 3.0% by mass or more and 50.0% by mass or less based on the total mass of the ink. As the water-soluble organic solvent, any of those usable in inkjet inks, such as alcohols, (poly)alkylene glycols, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds, may be used, and one or more kinds may be contained.

[0041] (Other additives) In addition to the above components, the ink may contain various additives, such as an antifoaming agent, a surfactant, a pH adjuster, a viscosity adjuster, an antirust agent, an antiseptic, an antifungal agent, an antioxidant, an antireducing agent, and a water-soluble resin, as necessary.

[0042] [Processing liquid] It is preferable to suppress a decrease in image quality due to a phenomenon in which adjacent ink dots are attracted to each other or mixed together due to the surface tension of the ink applied onto the recording medium. For this purpose, it is preferable to apply a treatment liquid for reducing the fluidity of the ink onto the recording medium before the first ink application step. The treatment liquid for reducing the fluidity of the ink is a liquid that has a function of increasing the viscosity of the entire ink or aggregating a part of the ink, such as the color material, by chemically reacting with or physically adsorbing the color material or resin that is a part of the ink.

[0043] (Ink viscosity increasing component) The treatment liquid may contain, without particular limitation, any conventionally known ink viscosity increasing component, such as polyvalent metal ions, organic acids, cationic resins, porous fine particles, etc. Among these, polyvalent metal ions and organic acids are particularly preferred. It is also preferred to contain multiple types of ink viscosity increasing components.

[0044] Examples of polyvalent metal ions include Ca. 2+ , Cu 2+ , Ni 2+ , Mg 2+ , Sr 2+ , B.A. 2+ and Zn 2+ Divalent metal ions such as Fe 3+ , Cr 3+ , Y 3+ and Al 3+ In order to add polyvalent metal ions to the treatment liquid, polyvalent metal salts (which may be hydrates) formed by combining polyvalent metal ions with anions can be used. Examples of anions include Cl. - , Br - , I - , ClO - , ClO2 - , ClO3 - , ClO4 - , NO2 - , NO3 - , SO4 2- , CO3 2- , HCO3 - , PO43- , HPO4 2- , and H2PO4 - Inorganic anions such as HCOO - , (COO - )2, COOH(COO - ), CH3COO - , C2H4(COO - )2, C6H5COO - , C6H4(COO - )2 and CH3SO3 - When a polyvalent metal ion is used, the content (mass %) of the polyvalent metal salt in the treatment liquid is preferably 1.00 mass % or more and 10.00 mass % or less based on the total mass of the treatment liquid.

[0045] The treatment liquid containing an organic acid has a buffering ability in the acidic range (less than pH 7.0, preferably pH 2.0 to 5.0), and thereby converts the anionic groups of the components present in the ink into an acid form and causes them to aggregate. Examples of the organic acid include monocarboxylic acids and salts thereof, such as formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrole carboxylic acid, furan carboxylic acid, picolinic acid, nicotinic acid, thiophene carboxylic acid, levulinic acid, and coumaric acid; dicarboxylic acids and salts thereof, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, and tartaric acid; tricarboxylic acids and salts thereof, such as citric acid and trimellitic acid; and tetracarboxylic acids and salts thereof, such as pyromellitic acid.

[0046] Examples of the cationic resin include resins having a structure of primary to tertiary amines, and resins having a structure of quaternary ammonium salts. Specific examples include resins having structures such as vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, and guanidine. In order to increase the solubility in the treatment liquid, the cationic resin may be used in combination with an acidic compound, or the cationic resin may be subjected to a quaternary treatment. When a cationic resin is used, the content (mass %) of the cationic resin in the treatment liquid is preferably 1.00 mass % or more and 10.00 mass % or less based on the total mass of the treatment liquid.

[0047] (solvent) The treatment liquid may contain water and / or an organic solvent as a solvent. In this case, the water used is preferably deionized by ion exchange or the like. The organic solvent that can be used in the treatment liquid is not particularly limited, and any known organic solvent can be used.

[0048] (Other additives) The treatment liquid may also contain various resins. By containing an appropriate resin, it is possible to increase the abrasion resistance and glossiness of the image, which is preferable. There is no particular limitation on the resin as long as it can coexist with the ink viscosity increasing component. In addition, a surfactant or a viscosity adjuster may be added to the treatment liquid to appropriately adjust its surface tension and viscosity. There is no particular limitation on the surfactant as long as it can coexist with the ink viscosity increasing component. For example, it can be selected from cationic surfactants, anionic surfactants, nonionic surfactants, amphoteric surfactants, fluorine-based surfactants, and silicone-based surfactants. It is also possible to use a mixture of two or more of these materials.

[0049] As the treatment liquid applying device which is the treatment liquid applying means, known treatment liquid applying devices such as a roll coater, a spray coater, a bar coater, an ink jet recording head, etc. can be used.

[0050] FIG. 2 is a schematic diagram showing the configuration of another image forming apparatus using the image recording method according to an embodiment of the present invention. In the image forming apparatus 200 in FIG. 2, the recording medium 201 is installed in a roll-like state on the unwinding device 205a. The unwinding device 205a and the winding device 205b, which are conveying means, rotate in the direction of the arrows to move the recording medium 201. Furthermore, after performing the ink application process by the ink application device 202, the heating and drying process by the heating and drying device 203, and the heating and pressurizing process by the heating and pressurizing device 204, the unwinding device 205a and the winding device 205b are rotated in the direction opposite to the arrows. This causes the area on the recording medium 201 to which the ink has been applied to be moved once again under the ink application device 202. Then, it becomes possible to easily apply ink a second time on the ink (ink film) applied to the recording medium by the first ink application process by the second ink application process.

[0051] There are no particular limitations on the unwinding device 205a and the winding device 205b, so long as they can transport the recording medium 201 by operating each of them.

[0052] 2. Moreover, the devices other than the unwinding device 205a and the winding device 205b of the image recording apparatus in FIG. 2 are similar to those of the image recording apparatus shown in FIG. 1, and therefore the description thereof will be omitted. EXAMPLES

[0053] The present embodiment will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples without departing from the gist of the present invention.

[0054] Example 1 [Image recording] Image recording was performed using an image recording apparatus in which a treatment liquid application device was further provided upstream of the ink application device in the conveying direction of the recording medium in addition to the image recording apparatus shown in FIG.

[0055] The recording medium was coated paper (product name: Aurora Coat, manufactured by Nippon Seishi Co., Ltd.) with a basis weight of 73.5 g / m2 The treatment liquid application device and the ink application device were each an inkjet recording head. The treatment liquid was uniformly applied to the surface of the recording medium at a concentration of 1.0 g / m by the inkjet recording head, which was the treatment liquid application device. 2 Then, black ink was uniformly applied at a rate of 6.0 g / m to the area on the recording medium to which the treatment liquid had been applied, using an inkjet recording head, which is an ink application device. 2 Granted.

[0056] The compositions of the treatment liquid and ink used here are as follows. <Processing solution> Calcium nitrate tetrahydrate 20 parts Acetylenol EH (product name, manufactured by Kawaken Fine Chemicals Co., Ltd.) 1 part Ethylene glycol 10 parts 69 parts deionized water <Ink> Carbon black MCF88 (Mitsubishi Chemical Corporation) 3 parts Styrene-acrylic acid-ethyl acrylate copolymer 8 parts 10 parts glycerin Ethylene glycol 5 parts 74 parts deionized water

[0057] The styrene-acrylic acid-ethyl acrylate copolymer contained in this ink is a resin particle with a melting temperature of 100°C.

[0058] Next, the recording medium to which the treatment liquid and ink had been applied was heated and dried using hot air. This hot air was blown for 10 seconds against the surface of the recording medium to which the treatment liquid and ink had been applied. At this time, the temperature of the hot air was adjusted so that the temperature of the recording medium was 90°C. The temperature of this recording medium was measured by infrared thermography in the area on the recording medium to which the treatment liquid and ink had been applied. When the surface of the area of ​​the recording medium to which the ink had been applied at this stage was observed with a scanning electron microscope, no melting of the resin particles in the ink was observed.

[0059] Next, the recording medium that had been heated and dried by the heating and drying device was heated and pressed. The heating and pressing device used had a heating and pressing device having a heating belt as a heating and pressing member. The heating belt was a belt with PFA bonded to the surface of nitrile rubber, and two of these heating belts were prepared, and the recording medium was sandwiched between the two heating belts from above and below to perform heating and pressing. At this time, the surface temperature of the heating belt was 115°C, and the heating belt and the recording medium were brought into contact with each other for 2 seconds at a pressure of 0.1 kPa. When the surface of the ink-applied region of the recording medium after this heating and pressing process was observed with a scanning electron microscope, it was confirmed that the resin particles in the ink had melted and an ink film had been formed.

[0060] Next, as a second ink application step, black ink was applied uniformly at 4.0 g / m onto the ink film on the heated and pressurized recording medium. 2 Thereafter, a heat drying step was carried out again under the same conditions as the first step using a heat drying device, to obtain a recording medium (recorded matter) on which an image was recorded.

[0061] [Evaluate the image] The obtained images were evaluated for image density and scratch resistance.

[0062] Image density is the brightness L * The evaluation was performed using L * was measured using a fluorescence spectrodensitometer (product name: FD-7, manufactured by Konica Minolta Japan, Inc.).

[0063] The scratch resistance of the image was evaluated using a Gakushin-type friction test (500g load, 10 rubs) on the image recorded on the recording medium one day after the image was recorded. The image after rubbing was visually observed and classified into the following four stages according to its condition. A: The surface of the recording medium is not exposed in the rubbed image area, and almost no rub marks are observed. B: There is no exposure of the surface of the recording medium in the rubbed image area, but rub marks are visible. C: Less than 5% of the rubbed image area has the surface of the recording medium exposed. D: 5% or more of the abraded image area has the surface of the recording medium exposed.

[0064] The pure water absorption coefficient in the dynamic liquid absorbency test of the recording medium was measured using an automatic scanning liquid absorption meter (product name: KM500win (product number: No. 2071, manufactured by Kumagai Riki Kogyo Co., Ltd.).

[0065] Example 2 The recording medium was a lightly coated paper (product name: Vannuovo V-FS, manufactured by Takeo Co., Ltd.) with a basis weight of 215 g / m 2 The evaluation was carried out in the same manner as in Example 1 except that the above was used.

[0066] Example 3 The amount of ink applied in the first ink application step was 7.2 g / m 2 , the amount of ink applied in the second ink application step was 0.8 g / m 2 The same evaluation as in Example 2 was carried out except that the above was changed to the above.

[0067] Comparative Example 1 8.0 g / m in the first ink application step 2 The same evaluation as in Example 2 was carried out except that the second ink application step was not carried out.

[0068] Comparative Example 2 The same evaluation as in Comparative Example 1 was carried out, except that the heating and pressurizing step was not carried out.

[0069] The evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Table 1 below.

[0070] [Table 1]

[0071] The disclosure of this embodiment includes the following method.

[0072] (Method 1) A first ink application step of applying an ink containing resin particles to a recording medium; A heating and drying step of heating and drying the recording medium to which the ink has been applied; A heating and pressing step of heating and pressing the heated and dried recording medium; A second ink application step of further applying the ink to the heated and pressed recording medium; An image recording method comprising: When the melting temperature of the resin particles is Te [°C], the temperature of the recording medium dried by the heating and drying step is T1 [°C], and the temperature of the recording medium heated and pressed by the heating and pressing step is T2 [°C], an image recording method characterized by satisfying the relationship T1 < Te < T2.

[0073] (Method 2) The water absorption coefficient of pure water of the recording medium is 30 μm / sec 1 / 2 The image recording method according to Method 1, wherein the above is satisfied.

[0074] (Method 3) The ink application amount in the first ink application step is 50% by mass or more and 90% by mass or less based on the total ink application amount in the first ink application step and the second ink application step. The image recording method according to Method 1 or 2.

[0075] (Method 4) In the heating and drying step, the heating and drying device for heating and drying the recording medium is a non-contact type heating and drying device that does not contact the recording medium. The image recording method according to any one of Methods 1 to 3.

[0076] (Method 5) In the heating and pressing step, the heating and pressing device for heating and pressing the recording medium is a contact type heating and pressing device that contacts the recording medium. The image recording method according to any one of Methods 1 to 4.

Explanation of Signs

[0077] 100 Image recording apparatus 101 Recording medium 102 Ink application device 103 Heating and drying device 104 Heating and pressing device 105 Conveying device 200 Image forming apparatus 201 Recording media 202 Ink application device 203 Heating drying equipment 204 Heating and Pressurizing Equipment 205a Unwinding device 205b Winding device

Claims

1. a first ink application step of applying an ink containing resin particles to a recording medium; a heat drying step of heating and drying the recording medium to which the ink has been applied; a heating and pressing step of heating and pressing the heated and dried recording medium; a second ink application step of further applying the ink to the heated and pressurized recording medium; An image recording method comprising the steps of: An image recording method characterized in that, when the melting temperature of the resin particles is Te [°C], the temperature of the recording medium heated and dried in the heating and drying process is T1 [°C], and the temperature of the recording medium heated and pressurized in the heating and pressurizing process is T2 [°C], the relationship T1<Te<T2 is satisfied.

2. The water absorption coefficient of the recording medium is 30 μm / sec. １／２ The image recording method according to claim 1, wherein the above-mentioned

3. 2. The image recording method according to claim 1, wherein the amount of ink applied in the first ink application step is 50% by mass or more and 90% by mass or less based on the total amount of ink applied in the first ink application step and the second ink application step.

4. 2. The image recording method according to claim 1, wherein in the heating and drying step, a heating and drying device for heating and drying the recording medium is a non-contact heating and drying device that does not come into contact with the recording medium.

5. 2. The image recording method according to claim 1, wherein in the heating and pressing step, a heating and pressing device for heating and pressing the recording medium is a contact-type heating and pressing device that comes into contact with the recording medium.

Images