JP2021130268A - Inkjet recording method - Google Patents

Abstract

To provide a transfer type inkjet recording method capable of effectively removing a wax residue on a transfer body without using a liquid component such as cleaning liquid and capable of recording a high-quality image.SOLUTION: There is provided an inkjet recording method for recording an image on a recording medium 108 using aqueous ink, which comprises: a wax application step of applying a wax on a transfer body 101; a reaction liquid application step; an intermediate image forming step; and a cleaning step of bringing a cleaning roller 109 into contact with the transfer body to remove a wax residue on the transfer body in this order. The surface temperature of the transfer body in the cleaning step is equal to or higher than a temperature where the needle penetration degree of the wax is 50 or more and a surface free energy γCL(mN/m) of the cleaning roller, a surface tension γW(mN/m) of the wax and a surface free energy γT(mN/m) of the transfer body satisfy a relation of γCL>γW>γT.SELECTED DRAWING: Figure 1

Description

The present invention relates to an inkjet recording method.

In the inkjet recording method, an image is recorded by directly or indirectly applying a liquid composition (ink) containing a coloring material to a recording medium such as paper. When the ink is applied to the recording medium, if the liquid component in the ink is excessively absorbed by the recording medium, the recording medium may have problems such as curl and cock ring. In order to prevent problems such as curling and cockling, for example, a method of forming an intermediate image on a transfer body, removing a liquid component contained in the intermediate image, and then transferring the intermediate image to a recording medium (hereinafter referred to as a method). A recording method that employs (also referred to as "transfer method") has been devised. Further, as a method of adding robustness to the recorded image, there are a method of applying a liquid laminating process to the entire surface of the printed matter including the image, a method of applying wax to the image, and the like.

From the viewpoint of improving productivity, it is desirable that the means for improving the robustness of the image is incorporated in a series of recording operations. As a method that can impart fastness to an image while suppressing the occurrence of defects such as curl and cock ring, there is a transfer method inkjet recording method that incorporates a step of applying wax to a transfer body.

However, in the case of the inkjet recording method of the transfer method described above, a part of wax (wax residue) that has not been transferred to the recording medium tends to remain on the transfer body after the intermediate image is transferred to the recording medium. If the wax residue is present on the transfer body, the intermediate image formed on the transfer body in the next step is likely to be cracked, and the quality of the recorded image is likely to be deteriorated. As a method for removing the wax residue on the transfer body, for example, a method of bringing a wiping roller to which a cleaning solution is applied into contact with the transfer body has been proposed (Patent Document 1).

Special Fair 7-115468 Gazette

However, in the case of the method proposed in Patent Document 1, the cleaning liquid used for removing the wax residue may remain on the transcript. Therefore, the intermediate image formed on the transfer body in the next step may be easily blurred, and there is a concern that the quality of the recorded image may be deteriorated. Further, when a means for removing a liquid component such as a cleaning liquid is provided from the transfer body after removing the wax residue, there arises a problem that the configuration of the recording device is complicated and the size of the recording device is significantly increased.

Therefore, an object of the present invention is to provide a transfer-type inkjet recording method capable of effectively removing wax residues on a transfer body and recording a high-quality image without using a liquid component such as a cleaning liquid. It is in.

That is, according to the present invention, it is an inkjet recording method for recording an image on a recording medium using a water-based ink, and includes a wax coating step of applying wax to a transfer body and a reactant that reacts with the water-based ink. A reaction solution applying step of applying the reaction solution to the transfer body, an intermediate image forming step of applying the water-based ink to the transfer body to form an intermediate image, and the intermediate image being brought into contact with the recording medium for transfer. The transfer step and the cleaning step of bringing the cleaning roller into contact with the transfer body to remove the wax residue on the transfer body are provided in this order, and the surface temperature of the transfer body in the cleaning step is the same as that of the wax. The degree of needle insertion is 50 or more, the surface free energy γ _CL (mN / m) of the _{cleaning roller, the surface tension γ W} (mN / m) of the wax, and the surface free energy γ of the transfer body. Provided is an ink-ink recording method characterized in that _T (mN / m) _{satisfies the relationship of γ CL} > γ _W > γ _T.

According to the present invention, it is possible to provide a transfer-type inkjet recording method capable of effectively removing wax residues on a transfer body and recording a high-quality image without using a liquid component such as a cleaning liquid. ..

It is a schematic diagram which shows an example of the structure of the transfer type inkjet recording apparatus. It is a schematic diagram which shows another example of the structure of the transfer type inkjet recording apparatus. It is a block diagram which shows an example of the control system of the inkjet recording apparatus shown in FIGS. 1 and 2. It is a block diagram which shows an example of the printer control part of the inkjet recording apparatus shown in FIGS. 1 and 2.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. In the present invention, when the compound is a salt, the salt is dissociated into ions and exists in the ink, but for convenience, it is expressed as "containing a salt". Further, the water-based reaction liquid and the water-based ink for inkjet may be simply referred to as "reaction liquid" and "ink". The physical characteristic value is a value at room temperature (25 ° C.) unless otherwise specified. When described as "(meth) acrylic acid" and "(meth) acrylate", they mean "acrylic acid, methacrylic acid" and "acrylate, methacrylate", respectively.

The inkjet recording method of the present invention is a method of recording an image on a recording medium using water-based ink, and has a wax coating step, a reaction solution applying step, an intermediate image forming step, a transfer step, and a cleaning step in this order. The wax application step is a step of applying wax to the transfer body. The reaction solution applying step is a step of applying a reaction solution containing a reactant that reacts with the aqueous ink to the transcript. The intermediate image forming step is a step of applying water-based ink to the transfer body to form an intermediate image. The transfer step is a step of bringing an intermediate image into contact with a recording medium and transferring the image. The cleaning step is a step of bringing the cleaning roller into contact with the transfer body to remove the wax residue on the transfer body. The surface temperature of the transfer material in the cleaning step is a temperature or higher at which the degree of needle insertion of the wax is 50 or higher. Further, the surface free energy γ _{CL (mN / m) of the cleaning roller, the surface tension γ W} (mN / m) of the wax, and the surface free energy γ _T (mN / m) of the transfer material are γ _CL > γ _W >. Satisfy the relationship of _{γ T.} Hereinafter, the details of the inkjet recording method of the present invention will be described with reference to the configuration of an inkjet recording apparatus that can be preferably used.

<Transfer type inkjet recording device>
First, a transfer type inkjet recording apparatus used in the inkjet recording method of the present invention will be described. FIG. 1 is a schematic view showing an example of the configuration of a transfer type inkjet recording device. Examples of the transfer method include a belt type that uses belt transfer; a drum type in which a transfer body is attached to the surface of a cylinder; and a tandem type that individually conveys transfer bodies set to an arbitrary size. The transfer-type inkjet recording apparatus 100 shown in FIG. 1 employs a drum-type transfer method. The inkjet recording device 100 is a single-wafer recording device that produces a recorded material by transferring an intermediate image to a recording medium 108 via a transfer body 101. In FIG. 1, the X direction, the Y direction, and the Z direction indicate the width direction (total length direction), the depth direction, and the height direction of the inkjet recording apparatus 100, respectively. The recording medium 108 is conveyed in the X direction.

The inkjet recording device 100 includes a transfer body 101, a wax layer forming device 110, a reaction liquid applying device 103, an ink applying device 104 having an inkjet head, a liquid removing device 105, a pressing member 106, and a cleaning roller 109. The transfer body 101 is supported by the support member 102. The wax layer forming apparatus 110 applies wax to the transfer body 102, and a wax layer is formed on the transfer body 101. The reaction solution applying device 103 applies the reaction solution containing the reactant that reacts with the ink to the transcript 101. The ink applying device 104 applies ink and a transfer auxiliary liquid to the transfer body 101 to which the reaction solution is applied, and an intermediate image is formed on the transfer body 101. The liquid removing device 105 removes the liquid component from the intermediate image on the transfer body 101. The intermediate image on the transfer body 101 from which the liquid component has been removed is transferred to the recording medium 108 by being in contact with the recording medium 108 such as paper and being pressed by the pressing member 106. The cleaning roller 109 is a member that removes the wax residue on the transfer body 101 by contacting the transfer body 101 after the intermediate image is transferred to the recording medium 108. The transfer body 101, the reaction liquid applying device 103, the inkjet head of the ink applying device 104, the liquid removing device 105, and the cleaning roller 109 each have a length in the Y direction corresponding to the width of the recording medium 108.

The transfer body 101 rotates about the rotation axis 102a of the support member 102 in the direction of the arrow A in FIG. The transfer body 101 moves due to the rotation of the support member 102. The reaction solution and the ink are sequentially applied to the moving transfer body 101 by the reaction solution application device 103 and the ink application device 104, and an intermediate image is formed on the transfer body 101. The intermediate image formed on the transfer body 101 moves to the liquid removing device 105 by the movement of the transfer body 101.

The intermediate image from which the liquid component has been removed by the liquid removing device 105 is in a state where the ink is concentrated as compared with the intermediate image before the liquid component is removed. The intermediate image from which the liquid component has been removed is moved by the transfer body 101 to the transfer unit in contact with the recording medium 108 conveyed by the recording medium transfer device 107. While the intermediate image is in contact with the recording medium 108, the pressing member 106 presses the transfer body 101, and the intermediate image is transferred onto the recording medium 108. After that, the residual portion of the intermediate image that could not be completely transferred to the recording medium 108 is removed by the cleaning roller 109. On the transfer body 101 after transfer, a residual portion of the intermediate image is present as a transfer residue in no small measure.

Since the wax is a component for imparting fastness to the image, it is first applied to the transfer body 101 to form a wax layer. Then, the reaction solution and the ink are sequentially applied onto the formed wax layer to form an intermediate image. Therefore, the wax that is in direct contact with the transfer body 101 tends to remain on the transfer body 101 as a residue (wax residue) in the intermediate image.

The thermal properties of the wax are used for transferring the intermediate image to the recording medium 108, applying the wax to the transfer body 101, cleaning the transfer body 101, and the like. When transferring the intermediate image to the recording medium 108 or cleaning the transfer body 101, it is preferable that the wax (wax residue) is in a state of fluidity, so that the surface temperature of the transfer body 101 is high. Is preferable. Specifically, the surface temperature of the transfer material is preferably equal to or higher than the melting point of the wax. On the other hand, when the wax is applied to the transfer body 101, it is preferable that the fluidity of the wax applied to the transfer body 101 is lowered, so that the surface temperature of the transfer body 101 is preferably low. Specifically, the surface temperature of the transfer material is preferably lower than the melting point of the wax. The surface temperature of the transfer body 101 can be varied by using the transfer body cooling device 111 and the transfer body heating device 112. As the transfer body cooling device 111, means such as laser cooling and collision jet cooling are used. Further, as the transfer body heating device 112, means such as hot air heating and flash heating by infrared light condensing are used.

FIG. 2 is a schematic view showing another example of the configuration of a transfer type inkjet recording device. The transfer type inkjet recording device 200 shown in FIG. 2 includes a cleaning liquid storage unit 201 in which the cleaning liquid is stored. The cleaning liquid in the cleaning liquid storage unit 201 is applied to the surface of the cleaning roller 109. Then, when the cleaning roller 109 containing the cleaning liquid comes into contact with the transfer body 101, the wax residue on the transfer body 101 can be removed more efficiently.

<Transfer>
The transfer body 101 (FIG. 1) has a surface layer including an image forming surface. As a member of the surface layer, various materials such as resin and ceramics can be appropriately used. A material having a high compressive elastic modulus is preferable in terms of durability and the like. Specific examples thereof include an acrylic resin, an acrylic silicone resin, a fluorine-containing resin, and a condensate obtained by condensing a hydrolyzable organosilicon compound. It is preferable that the surface layer is hard to get wet with wax from the viewpoint of transferability of an intermediate image, cleaning property of wax residue, and the like. Therefore, the surface layer may be subjected to a surface treatment for reducing the surface free energy. Examples of the surface treatment include frame treatment, corona treatment, plasma treatment, polishing treatment, roughening treatment, surfactant treatment, silane coupling treatment and the like. Further, any surface shape can be provided on the surface layer.

The transfer material preferably has a compression layer having a function of absorbing pressure fluctuations on the support member side of the surface layer. By providing the compression layer, the compression layer absorbs the deformation, disperses the fluctuation against local pressure fluctuations, and can maintain good transferability even during high-speed printing. Examples of the member of the compression layer include acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, and silicone rubber. When molding the above rubber material, a predetermined amount of vulcanizing agent, vulcanization accelerator, etc. are blended, and further, a filler such as a foaming agent, hollow fine particles, or salt is blended as necessary to form a porous structure. Is preferable. As a result, since the bubble portion is compressed with a volume change in response to various pressure fluctuations, deformation in directions other than the compression direction is small, and more stable transferability and durability can be obtained. The porous rubber material includes a continuous pore structure in which the pores are continuous with each other and an independent pore structure in which each pore is independent, and any structure may be used.

The transfer material preferably has an elastic layer between the surface layer and the compression layer. As the member of the elastic layer, various materials such as resin and ceramics can be appropriately used. Various elastomer materials and rubber materials are preferably used in terms of processing characteristics and the like. Specifically, a copolymer of fluorosilicone rubber, phenylsilicone rubber, fluororubber, chloroprene rubber, urethane rubber, nitrile rubber, ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber, and ethylene / propylene / butadiene. , Nitrile butadiene rubber and the like. Among them, silicone rubber, fluorosilicone rubber, and phenylsilicone rubber are preferable in terms of dimensional stability and durability because they have a small compression set. In addition, the change in elastic modulus with temperature is small, which is preferable in terms of transferability.

Various adhesives or double-sided tape may be used between the layers (surface layer, elastic layer, compression layer) constituting the transfer body to fix and hold them. Further, a reinforcing layer having a high compressive elastic modulus may be provided in order to suppress lateral elongation when mounted on the device and to maintain elasticity. Further, the woven fabric may be used as a reinforcing layer. The transfer body can be produced by arbitrarily combining each layer made of the above-mentioned materials. The size of the transfer body can be freely selected according to the target print image size. Examples of the shape of the transfer body include a sheet shape, a roller shape, a belt shape, and an endless web shape.

<Support member>
The transfer body 101 is supported on the support member 102 (FIG. 1). Various adhesives or double-sided tape may be used to support the transfer body. Further, the transfer body may be supported on the support member by using an installation member made of a material such as metal, ceramics, or resin attached to the transfer body.

The support member is required to have a certain level of structural strength from the viewpoint of transport accuracy and durability. As the material of the support member, metal, ceramics, resin or the like is preferably used. Among them, a material that can withstand the pressure during transfer, has rigidity and dimensional accuracy, and can reduce inertia during operation to improve control responsiveness is preferable. Examples of such a material include aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, polyethylene, polyethylene terephthalate, nylon, polyurethane, silica ceramics, alumina ceramics and the like.

<Wax layer forming device>
The wax layer forming apparatus 110 includes a wax accommodating portion 110a for accommodating wax, and wax applying members 110b and 110c for applying the wax contained in the wax accommodating portion 110a onto the transfer body 101 (FIG. 1). Wax is applied onto the transfer body 101 by the wax layer forming apparatus 110, and a thin film wax layer is formed on the transfer body 101. A reaction solution and ink are sequentially applied onto the formed wax layer to form an intermediate image.

The wax is contained in the wax accommodating portion 110a in a liquid state showing fluidity, and is applied to the transfer body 101 in the liquid state via the wax applying members 110b and 110c. The surface temperature of the transfer body 101 at the position where it comes into contact with the wax-imparting member 110c (the position indicated by “F” in FIG. 1) is preferably controlled to a temperature lower than the melting point of the wax. As a result, the wax applied to the transfer body 101 is cooled and solidified, and it becomes easy to form a thin-film wax layer. The thickness of the wax layer is preferably uniform. The thickness of the wax layer is preferably 5 μm or less, and more preferably 3 μm or less. If the thickness of the wax layer is more than 5 μm, cracks may easily occur in the recorded image. It is presumed that such cracks are generated by drying and shrinking the wax layer due to heat and pressure when the intermediate image is transferred to the recording medium.

In order to apply the wax to the transfer body, various conventionally known devices can be appropriately used. Specific examples thereof include a gravure offset roller, an inkjet head, a die coating device (die coater), and a blade coating device (blade coater). In the wax layer forming apparatus 110 shown in FIGS. 1 and 2, the wax applying member 110b corresponds to the gravure offset roller, and the wax applying member 110c corresponds to the offset roller.

<Wax>
As waxes, natural waxes such as beeswax, lanolin, carnauba wax, candelilla wax, and montan wax; petroleum waxes such as paraffin wax and microcrystalin wax; synthetic waxes such as Fisher Tropsch wax, polyethylene wax, polypropylene wax, and oxide wax. In addition to modified waxes such as urethane-modified waxes and alcohol-modified waxes; α-olefin-maleic anhydride copolymer waxes and the like can be mentioned. Among them, it is preferable to use at least one wax selected from the group consisting of microcrystalline wax, Fischer-Tropsch wax, polyolefin wax, paraffin wax, and modified products thereof.

The melting point of the wax can be measured according to the temperature measurement pattern of ASTM D3418. Specifically, using a thermal analyzer (for example, trade name "DSC-7" (manufactured by PerkinElmer)), the temperature rise rate is 10 ° C./min, and the maximum melting temperature measured according to the temperature measurement pattern of ASTM D3418. The peak top value of can be the melting point (° C.) of the wax.

<Reaction solution applying device>
The reaction solution application device 103 includes a reaction solution accommodating unit 103a for accommodating the reaction solution, and reaction solution application members 103b and 103c for applying the reaction solution contained in the reaction solution accommodating unit 103a onto the transcript 101 (FIG. 1). .. As the reaction solution applying device, various conventionally known devices capable of applying the reaction solution to the transcript can be appropriately used. Specific examples thereof include a gravure offset roller, an inkjet head, a die coating device (die coater), and a blade coating device (blade coater). In the reaction solution applying device 103 shown in FIGS. 1 and 2, the reaction solution applying member 103b corresponds to the gravure offset roller, and the reaction solution applying member 103c corresponds to the offset roller.

The reaction solution is applied to the transfer body before applying the ink. By applying the reaction solution to the transfer body before applying the ink, bleeding in which the ink droplets ejected by the inkjet method are mixed with each other, and the ink droplets that landed first are the droplets of ink that landed later. The beading that is attracted to the ink can be suppressed.

<Reaction solution>
The reaction solution contains a reactant that reacts with the ink. This reactant is a component that aggregates components having anionic groups (resins, self-dispersing pigments, etc.) in the ink when it comes into contact with the ink. Examples of the reactant include a cationic component such as a polyvalent metal ion and a cationic resin, and an organic acid.

Polyvalent metal ions include ^{divalent metal ions such as Ca 2+} , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Sr ²⁺ , Ba ²⁺ and Zn ²⁺ ; trivalents such as Fe ³⁺ , Cr ³⁺ , Y ³⁺ and Al ^3+. Metal ions; In order to contain the polyvalent metal ion in the reaction solution, a polyvalent metal salt (which may be a hydrate) composed of a combination of the polyvalent metal ion and an anion can be used. As anions, Cl ⁻ , Br ⁻ , I ⁻ , ClO ⁻ , ClO ₂ ⁻ , ClO ₃ ⁻ , ClO ₄ ⁻ , NO ₂ ⁻ , NO ₃ ⁻ , SO ₄ ^2- , CO ₃ ^2- , HCO ₃ ⁻ , PO ^{₄ 3-,} _{HPO 4} ^2-, and _H 2 PO ₄ ^- inorganic anions such _{^{as; HCOO -, (COO -)}} 2, COOH (COO -), CH 3 COO -, C 2 H 4 (COO -) 2 , C ₆ H ₅ COO ⁻ , C ₆ H ₄ (COO ⁻ ) ₂ and CH ₃ SO ₃ ⁻ and other organic anions. When polyvalent metal ions are used as the reactant, the content (mass%) of the polyvalent metal salt-equivalent reactant in the reaction solution is 1.00% by mass or more and 10.00% by mass based on the total mass of the reaction solution. % Or less is preferable.

The reaction solution containing an organic acid has a buffering ability in an acidic region (pH less than 7.0, preferably pH 2.0 to 5.0), so that the anionic group of the component present in the ink is made into an acid type. Aggregate. Organic acids include formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrolcarboxylic acid, furancarboxylic acid, picolinic acid, nicotinic acid, thiophenecarboxylic acid, levulinic acid, coumarin acid and the like. Carous acid and its salts; dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, tartaric acid, and their salts and hydrogen. Salts; tricarboxylic acids such as citric acid and trimellitic acid, and salts and hydrogen salts thereof; tetracarboxylic acids such as pyromellitic acid, and salts and hydrogen salts thereof; and the like.

Examples of the cationic resin include a resin having a structure of a primary amine and a resin having a structure of a quaternary ammonium salt. Examples of the cationic resin include resins having a structure such as vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, and guanidine. In order to increase the solubility in the reaction solution, the cationic resin and the acidic compound can be used in combination, or the cationic resin can be quaternized. When a cationic resin is used as the reactant, the content (mass%) of the cationic resin in the reaction solution is 1.00% by mass or more and 10.00% by mass or less based on the total mass of the reaction solution. preferable.

The reaction solution may contain, as a component other than the reactant, the same components as water, a water-soluble organic solvent, and other additives that can be contained in the ink described later.

<Ink application device>
The transfer type inkjet recording device 100 includes an ink applying device 104 that applies ink to the transfer body 101 (FIG. 1). On the transfer body, the reaction solution and the ink come into contact with and mix with each other to form an intermediate image. Then, the liquid component is removed from the intermediate image by the liquid removing device.

As an ink applying device for applying ink, an inkjet head that ejects ink by an inkjet method is used. The inkjet head is a form in which an electric-heat converter causes a film to boil in the ink to form bubbles to eject the ink; a form in which the ink is ejected by an electric-mechanical converter; an ink is ejected using static electricity. The form to be used; etc. can be mentioned. As the inkjet head, a known inkjet head can be used. Of these, an inkjet head that uses an electric-heat converter is preferable from the viewpoint of performing high-speed, high-density printing. It is drawn by receiving an image signal and applying the required amount of ink to each position.

The inkjet head of the ink application device 104 shown in FIG. 1 is a full-line head extended in the Y direction, and the nozzles are arranged in a range covering the width of the image recording area of the maximum usable recording medium 108. Has been done. The inkjet head has an ink ejection surface having a nozzle opened on the lower surface (transfer body 101 side) thereof. The ink ejection surface faces the surface of the transfer body 101 with a minute gap (about several millimeters).

The amount of ink applied can be expressed by the image density (duty) and the ink thickness. Further, the average value obtained by multiplying the mass of each ink dot by the number of applied ink dots and dividing by the printing area may be used as the applied ^{amount of ink (g / m 2).} The maximum amount of ink applied in the image region indicates the amount of ink applied in an area of at least 5 mm ² or more in the region used as information of the transfer body from the viewpoint of removing the liquid component in the ink.

The ink application device may have a plurality of inkjet heads in order to apply color inks of each color on the transfer body. For example, when forming an image of each color using yellow ink, magenta ink, cyan ink, and black ink, the ink applying device has four inkjet heads for ejecting four types of ink onto a transfer body. The four inkjet heads are arranged so as to be arranged in the X direction.

Further, the ink applying device may have an inkjet head that ejects a substantially transparent clear ink that does not contain a coloring material or contains a very small amount. The clear ink can be used to form an intermediate image together with the reaction solution and the color ink. For example, clear ink can be used to improve the glossiness of the image. The content of the resin component to be blended in the clear ink may be appropriately adjusted so that the image after transfer is given a glossy feeling. Further, the discharge position of the clear ink may be controlled. The clear ink is preferably present on the surface layer side of the color ink in the finally obtained image. Therefore, in the transfer body type inkjet recording apparatus, it is preferable to apply the clear ink to the transfer body before the color ink. That is, it is preferable that the inkjet head for clear ink is arranged on the upstream side of the inkjet head for color ink in the moving direction of the transfer body facing the ink applying device.

In addition, clear ink can also be used to improve the transferability of the intermediate image from the transfer body to the recording medium. For example, the clear ink can be used as a transferability improving liquid by blending a large amount of a component exhibiting adhesiveness with the clear ink. For example, the inkjet head for clear ink is arranged on the downstream side of the inkjet head for color ink in the moving direction of the transfer body facing the ink applying device. Then, after applying the color ink to the transfer body, the clear ink is further applied to make the clear ink present on the outermost surface of the intermediate image. When the intermediate image is transferred to the recording medium, the clear ink on the outermost surface adheres to the recording medium with an appropriate adhesive force, so that the transferability is improved.

<Ink>
The ink usually contains a colorant, resin particles, an aqueous medium, and the like. Hereinafter, each component of the ink will be described.

(Color material)
Pigments and dyes can be used as the coloring material. The content of the coloring material in the ink is preferably 0.5% by mass or more and 15.0% by mass or less, and 1.0% by mass or more and 10.0% by mass or less, based on the total mass of the ink. Is even more preferable.

Examples of the pigment include inorganic pigments such as carbon black and titanium oxide; organic pigments such as azo-based, phthalocyanine-based, quinacridone, isoindolinone-based, imidazolone-based, diketopyrrolopyrrole-based, and dioxazine-based pigments. When pigments are classified by the dispersion method, resin-dispersed pigments dispersed with a resin dispersant; self-dispersed pigments in which hydrophilic groups such as anionic groups are directly bonded to the particle surface of the pigment or through other atomic groups. Can be mentioned. Pigments with different dispersion methods may be used in combination.

As the resin dispersant, a known resin dispersant used for water-based ink for inkjet can be used. Of these, 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 form of the resin include block copolymers, random copolymers, graft copolymers, and combinations thereof.

The resin dispersant in the ink may be in a state of being dissolved in a liquid medium, or may be in a state of being dispersed as resin particles in the liquid medium. The water-soluble resin means a resin that does not form particles whose particle size can be measured by a dynamic light scattering method when neutralized with an acid value and an equivalent amount of alkali.

A hydrophilic unit having a hydrophilic group such as an anionic group can be formed by polymerizing a monomer having a hydrophilic group. Examples of the monomer having a hydrophilic group include an acidic monomer having an anionic group such as (meth) acrylic acid and maleic acid, and an anionic monomer such as an anhydride or a salt of these acidic monomers. Examples of the cation constituting the salt of the acidic monomer include ions such as lithium, sodium, potassium, ammonium and organic ammonium.

A hydrophobic unit that does not substantially have a hydrophilic group such as an anionic group can be formed by polymerizing a monomer having a hydrophobic group. Examples of the monomer having a hydrophobic group include a monomer having an aromatic ring such as styrene, α-methylstyrene and benzyl (meth) acrylate; and an aliphatic such as ethyl (meth) acrylate, methyl (meth) acrylate and butyl (meth) acrylate. Monomers having a group ((meth) acrylic ester-based monomers); and the like can be mentioned.

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

As the self-dispersing pigment, an anionic group such as a carboxylic acid group, a sulfonic acid group, or a phosphonic acid group is used, which is bonded to the particle surface of the pigment directly or via another atomic group (-R-). be able to. The anionic group may be of either an acid type or a salt type, and when it is a salt type, it may be in a state in which a part thereof is dissociated or a state in which all of the anionic group is dissociated. Examples of the cation that becomes a counter ion when the anionic group is a salt type include alkali metal cations; ammonium; organic ammonium; and the like. 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, and a carbonyl group. , Ester group, ether group and the like. Moreover, you may make a group which combined these groups.

As the dye, it is preferable to use a dye having an anionic group. Examples of the dye include azo-based, triphenylmethane-based, (aza) phthalocyanine-based, xanthene-based, and anthrapyridone-based dyes.

(Resin particles)
The resin particles do not have to contain a coloring material. By using an ink containing resin particles, the quality and fixability of the obtained image can be improved.

Examples of the resin particles include resin particles composed of various resins such as olefin-based, polystyrene-based, urethane-based, and acrylic-based. The weight average molecular weight (Mw) of the resin constituting the resin particles is preferably 1,000 or more and 2,000,000 or less. The volume average particle diameter of the resin particles measured by the dynamic light scattering method is preferably 10 nm or more and 1,000 nm or less, and more preferably 100 nm or more and 500 nm or less. The content (mass%) of the resin particles in the ink is preferably 1.0% by mass or more and 50.0% by mass or less, and 2.0% by mass or more and 40.0% by mass, based on the total mass of the ink. The following is more preferable.

(Aqueous medium)
The ink is water or an aqueous ink containing an aqueous medium which is a mixed solvent of water and a water-soluble organic solvent. As the water, it is preferable to use deionized water or ion-exchanged water. The water content (mass%) 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 the 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, those that can be used for ink jet inks such as alcohols, (poly) alkylene glycols, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds can be used.

(Other additives)
In addition to the above components, inks include defoamers, surfactants, pH adjusters, viscosity regulators, rust inhibitors, preservatives, fungicides, antioxidants, antioxidants, and water-soluble agents, if necessary. Various additives such as sex resins can be contained.

<Liquid removal device>
The liquid removing device 105 is a device that removes a liquid component from an intermediate image formed on the transfer body 101 (FIG. 1). According to the liquid removing device, the liquid component can be removed from the intermediate image by, for example, a method of heating, a method of blowing low humidity air, a method of reducing the pressure, or the like. As a method by heating, a method using an infrared heater is preferable because it can be efficiently heated in a short time. Further, the liquid absorbing device may be a liquid absorbing device that employs a means for absorbing and removing a liquid component from the intermediate image by pressing a liquid absorbing member containing a porous body against the intermediate image.

The liquid component to be removed, which is included in the intermediate image, usually does not have a constant shape, has fluidity, and has a substantially constant volume. The liquid component is, for example, water or an organic solvent contained in an ink or a reaction solution.

The liquid absorbing member containing the porous body may be arranged on the outer peripheral surface of the roller, or the liquid absorbing member itself may be formed in the shape of an endless sheet and may be circulated. .. From the viewpoint of protecting the intermediate image, it is preferable to synchronize the moving speed of the liquid absorbing member with the peripheral speed of the transfer body.

In order to suppress the adhesion of solids in the ink, the pore size of the porous body used for the liquid absorbing member is preferably 10 μm or less. The pore diameter of a porous body means the average diameter of a large number of pores. The pore size (average diameter) of the porous body can be measured by a method such as a mercury intrusion method, a nitrogen adsorption method, or SEM image observation.

<Pressing member for transfer>
The intermediate image after removing the liquid on the transfer body 101 is brought into contact with the recording medium 108 conveyed by the recording medium transfer device 107 and pressed by the transfer pressing member 106 to transfer the intermediate image to the recording medium 108. (Fig. 1). By transferring the intermediate image after removing the liquid component to the recording medium, it is possible to record the image while suppressing the occurrence of defects such as curl and cock ring.

The pressing member is required to have a certain level of structural strength from the viewpoint of transport accuracy and durability of the recording medium. As the material of the pressing member, metal, ceramic, resin or the like is preferable. Among them, a material that can withstand the pressure during transfer, has dimensional accuracy, and can reduce inertia during operation to improve control responsiveness is preferable. Examples of such a material include aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, polyethylene, polyethylene terephthalate, nylon, polyurethane, silica ceramics, alumina ceramics and the like.

When the intermediate image on the transfer body is transferred to the recording medium, the time for the pressing member to press the transfer body (pressing time) is within a range in which the transfer is performed well and the durability of the transfer body is not impaired. It is preferable that the amount is 5 ms or more and 100 ms or less. The pressing time is the time during which the recording medium and the transfer body are in contact with each other. The pressing time can be obtained by measuring the surface pressure using a surface pressure distribution measuring device (trade name "I-SCAN", manufactured by Nitta) and dividing the length of the pressurized region in the transport direction by the transport speed. can.

The pressure at which the pressing member presses the transfer body is preferably within a range in which the transfer is performed well and the durability of the transfer body is not impaired. The pressure at which the pressing member presses the transfer body is preferably 9.8 N / cm ² (1 kg / cm ² ) or more and 294.2 N / cm ² (30 kg / cm ² ) or less. The pressure at which the pressing member presses the transfer body is the nip pressure between the recording medium and the transfer body. The pressure at which the pressing member presses the transfer body is measured by measuring the surface pressure using a surface pressure distribution measuring device (trade name "I-SCAN", manufactured by Nitta), and the load in the pressure region is divided by the area. Obtainable.

The temperature at which the pressing member presses the transfer body is preferably a temperature equal to or higher than the glass transition point or the softening point of the resin constituting the resin particles contained in the ink. It is preferable to control the temperature at which the pressing member presses the transfer body by using a heating means for heating the intermediate image on the transfer body, the transfer body, and the recording medium. Examples of the shape of the transfer means include a roller shape and the like.

<Recording medium and recording medium transfer device>
The recording medium transfer device 107 that conveys the recording medium 108 includes a recording medium feeding roller 107a and a recording medium winding roller 107b (FIG. 1). Then, the recording medium transport device 107 transports the recording medium 108 in the direction of the arrow C. As the recording medium, a conventionally known recording medium can be used. Examples of the recording medium include a long object wound in a roll shape and a single leaf object cut into a predetermined size. Examples of the material of the recording medium include paper (including cardboard such as corrugated cardboard), resin, wood, and metal.

<Cleaning roller>
The cleaning roller 109 is a member that removes the wax residue on the transfer body 101 by contacting the transfer body 101 after the intermediate image is transferred to the recording medium 108 (FIG. 1). The surface temperature of the transfer body in the cleaning step is the surface temperature of the transfer body 101 at the cleaning position (the position indicated by “E” in FIG. 1). As a method for removing the wax residue on the transfer body, there are various methods other than the method using a roller-shaped member such as a cleaning roller. For example, blade wiping that physically scrapes the residue using a blade; wet blade wiping that physically scrapes the residue using a blade to which a liquid is applied; a method of contacting a porous body to adsorb wax residue; ultrasonic cleaning Method; etc. However, in the case of the method of removing the wax residue using a blade-shaped member, scratches by the blade may easily occur on the surface of the transfer body. Further, in the case of the method of removing the wax residue using a member to which a liquid is applied, the liquid used may remain on the transfer body, which makes it difficult to apply the wax or the reaction solution satisfactorily thereafter. , Transfer defects may easily occur. Therefore, in the cleaning step, the cleaning roller, which is a roller-shaped cleaning member, is brought into contact with the transfer body to remove the wax residue on the transfer body.

The surface temperature of the transfer material in the cleaning step is set to a temperature at which the degree of needle insertion of the wax is 50 or more so that the wax residue can be effectively removed by contact with the cleaning roller without using a member to which the liquid is applied. Further, the surface free energy γ _{CL (mN / m) of the cleaning roller, the surface tension γ W} (mN / m) of the wax, and the surface free energy γ _T (mN / m) of the transfer material are γ _CL > γ _W >. Satisfy the relationship of _{γ T.}

The degree of needle penetration of wax is a physical property value that is an index of the hardness of petroleum asphalt and petroleum wax, and is 10 times the length (mm) of a specified needle vertically entering a sample (wax) held at a constant temperature. It is represented by the value of. The method for measuring the degree of needle insertion is specified in JIS K 2207: 2006 (petroleum asphalt). In the cleaning step, the surface temperature of the transfer body in contact with the cleaning roller is set to a temperature at which the degree of needle insertion of the wax is 50 or more. As a result, the wax residue exhibits fluidity, so that the wax easily adheres to the cleaning roller.

The higher the fluidity of the wax, the more sticky it becomes, so that it is more likely to adhere to the cleaning roller. Therefore, it is preferable that the surface temperature of the transfer material in the cleaning step is equal to or higher than the melting point of the wax. Further, the temperature of the cleaning roller in the cleaning step is preferably set to a temperature at which the degree of needle insertion of the wax is 50 or higher, and preferably equal to or higher than the melting point of the wax. By controlling the surface temperature of the transfer body and the temperature of the cleaning roller in the cleaning step as described above, the adhesiveness of the wax residue sandwiched between the transfer body and the cleaning roller is further enhanced. Thereby, the removability (cleanability) of the wax residue can be further improved.

In the cleaning step, the surface free energy γ _CL (mN / m) _{of the cleaning roller, the surface tension γ W} (mN / m) of the _{wax, and the surface free energy γ T} (mN / m) of the _{transfer body are converted into γ CL.} Control is performed so as to satisfy the relationship of> γ _W > γ _T. As a result, the wax residue is easily repelled on the transfer body, and the wax residue is easily attached to the cleaning roller, so that the cleaning property can be improved. The surface free energy γ _CL (mN / m) of the cleaning roller is preferably 10 mN / m or more higher than _{the surface tension γ W (mN / m) of the wax.}

The surface temperature of the transfer body is set to a temperature at which the degree of needle insertion of the wax is 50 or more, specifically, after the transfer of the intermediate image until the cleaning roller comes into contact with the transfer roller. The contact pressure when the cleaning roller is brought into contact with the transfer body ^{is preferably 10 kgf / cm 2} or more. By increasing the contact pressure, the contact area between the surface of the cleaning roller and the wax residue is expanded. Therefore, it is possible to make it easier for the wax residue on the transfer body to adhere to the cleaning roller.

<Control system>
FIG. 3 is a block diagram showing an example of a control system for the inkjet recording apparatus shown in FIGS. 1 and 2. In FIG. 3, 301 is a recording data generation unit such as an external print server, 302 is an operation control unit such as an operation panel, and 303 is a printer control unit for executing a recording process. Reference numeral 304 denotes a recording medium transport control unit for transporting the recording medium, and reference numeral 305 is an inkjet device.

FIG. 4 is a block diagram showing an example of a printer control unit of the inkjet recording apparatus shown in FIGS. 1 and 2. 401 is a CPU that controls the entire printer, 402 is a ROM for storing the control program of the CPU 401, and 403 is a RAM for executing the program. Reference numeral 404 is an integrated circuit (Application Specific Integrated Circuit: ASIC) for a specific application. The ASIC 404 includes a network controller, a serial IF controller, a head data generation controller, a motor controller, and the like. Reference numeral 405 is a liquid removing device control unit for driving the liquid removing device 105, which is command-controlled from the ASIC 404 via the serial IF. Reference numeral 407 is a transfer body drive control unit for driving the transfer body drive motor 408, which is also command-controlled from the ASIC 304 via the serial IF. Reference numeral 409 is a head control unit, which generates final ejection data of the inkjet device 305, generates a drive voltage, and the like. Reference numeral 410 denotes a wax layer forming device control unit for driving the motor 411 in the wax layer forming device. Reference numeral 412 is a cleaning device control unit for driving the motor 413 in the cleaning device, and 413 is a heating / cooling device control unit for controlling the heating device and the cooling device.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded. Unless otherwise specified, the amounts of components described as "parts" and "%" are based on mass.

In the following examples, a transfer type inkjet device 100 having the configuration shown in FIG. 1 was used. The reaction solution application device 103 and the ink application device 104 of the transfer type inkjet recording device 100 were filled with the reaction solution and the ink, respectively. The transfer body 101 was fixed to the support member 102 using a double-sided adhesive tape.

Wax was applied to the transfer body 101 using the wax layer forming apparatus 110, and a wax layer having a thickness of 0.5 μm was formed on the transfer body 101. The thickness of the wax layer was adjusted by making a difference in the rotation speeds of the wax applying member 110b and the wax applying member 110c. The surface temperature of the transfer body 101 when applying the wax (the surface temperature of the transfer body at the position indicated by “F” in FIG. 1) was set to 50 ° C. After the wax was applied, the reaction solution was applied to the region on the transfer body 101 where the wax layer was formed using the reaction solution application device 103 so that the application amount was 0.6 g / m ² . The amount of the reaction solution applied was adjusted by making a difference between the rotation speeds of the reaction solution application member 103b and the reaction solution application member 103c. The thickness of the wax layer was measured using a laser microscope (trade name "OPTELICS (registered trademark) HYBRID", manufactured by Lasertec). Specifically, the thickness of the wax layer was measured at four random locations on the transfer body at a magnification of 50 times that of the objective lens, and the average value was taken as the “wax layer thickness”.

An inkjet head (recording head) of a type that ejects ink by an on-demand method equipped with an electric-heat conversion element is used as an ink applying device 104, and ink is applied to a region on the transfer body 101 where wax and a reaction solution are applied. Was given.

As the liquid removing device 105, a device having a liquid absorbing member containing a porous body was used. The moving speed of the liquid absorbing member (porous body) was controlled to be the same as the rotation speed of the transfer body 101. The moving speed of the liquid absorbing member was 0.4 m / sec. A liquid absorbing member was immersed in a liquid containing 95.0 parts of ethanol and 5.0 parts of water, the liquid was permeated into the voids of the porous body, and then the voids were replaced with water. A pressure was applied to the member pressing the liquid absorbing member so that the nip pressure (average pressure) between the transfer body 101 and the liquid absorbing member was 2 kg / cm ^2.

The recording medium feeding roller 107a and the recording medium winding roller 107b were driven to convey the recording medium 108 at a speed of 0.6 m / sec, which is equivalent to the rotation speed of the transfer body 101. The recording medium 108 and the intermediate image were brought into contact with each other between the transfer body 101 and the pressing member 106, the intermediate image was transferred from the transfer body 101 to the recording medium 108, and the solid image was recorded on the recording medium 108. As the recording medium 108, coated paper (trade name “Aurora Coat”, manufactured by Nippon Paper Industries, Basis weight 157 g / m ² ) was used. The nip pressure between the transfer body 101 and the pressing member 106 was adjusted to ^{10 kg / cm 2.}

After the intermediate image was transferred to the recording medium 108, the cleaning roller 109 was brought into forced contact with the surface of the transfer body 101. The contact time between the transfer body 101 and the cleaning roller 109 was set to 25 ms. The temperature of the cleaning roller 109 was adjusted by an internal heater built in the cleaning roller 109. The temperature of the transfer body 101 during wax application and cleaning (the surface temperature of the transfer body at the positions indicated by “E” and “F” in FIG. 1) is the transfer body cooling device 111 and the transfer body heating device. Adjusted using 112. A spiral cooler (trade name "spiral cooler KSC200A", manufactured by Orion) was used as the cooling source of the transfer body cooling device 111. A xenon flash lamp (trade name "L2187", manufactured by Hamamatsu Photonics) was used as the heating source of the transfer body heating device 112. The surface temperature of the transfer body and the surface temperature of the cleaning roller were measured using a radiation thermometer (trade name "IT-545", manufactured by HORIBA, Ltd.).

<Transfer>
(Transfer 1)
A polyethylene terephthalate (PET) sheet having a thickness of 0.5 mm was prepared as a base material. A silicone rubber having a thickness of 0.3 mm (trade name "KE12", manufactured by Shin-Etsu Chemical Co., Ltd.) was disposed on the surface of this base material to obtain a transferred product 1.

(Transfer 2)
Glycydoxypropyltriethoxysilane and methyltriethoxysilane were mixed at a molar ratio of 1: 1 and heated under reflux to obtain a condensate. The obtained condensate was mixed with a photocationic polymerization initiator (trade name "SP150", manufactured by ADEKA) to obtain a mixture. The surface of the base material was subjected to atmospheric pressure plasma treatment so that the contact angle of water was 10 ° or less. After applying the obtained mixture to the surface of the substrate, UV irradiation was performed using a high-pressure mercury lamp so that the integrated exposure amount was 5,000 mJ / cm ^2. Then, it was thermoset at 150 ° C. for 2 hours to obtain a transferred product 2 having a surface layer having a thickness of 0.5 μm formed on the surface of the substrate.

(Transcribers 3 and 4)
A PET film (trade name "Tetron (registered trademark)", manufactured by Teijin Limited) was used as the transfer body 3. Further, the trade name "Kapton Sheet" (manufactured by DuPont) was used as the transfer body 4.

(Measurement of surface free energy)
The surface free energy of the transcript was measured using a contact angle meter (trade name "DropMaster700", manufactured by Kyowa Interface Science). Specifically, the contact angles with respect to a plurality of liquids (water, diiodomethane, formamide, n-hexadecan, and ethylene glycol) whose surface free energy is known were measured, and the surface free energy was calculated from the "Kitasaki-field formula". .. The types of transcripts 1 to 4 are shown in Table 1.

<Wax>
The surface tension of the wax showing fluidity at a needle insertion degree of 50 or more was measured using a surface tension meter (trade name "DSA100HP", manufactured by Sanyo Trading Co., Ltd.). The degree of needle insertion of wax was measured using a needle insertion test device (trade name "KA-1", manufactured by Kansai Kikai Seisakusho). As the needle, a stainless steel (SUS440-c) needle having a diameter of 1 mmφ and a mass of 2.5 g was used. Further, a 45 g needle holder and a 50 g copper weight were used. Wax was placed in a sample container having an inner diameter of 55 mm and a depth of 35 mm so as to have a depth of 10 mm or more. This sample container was placed in a glass container (constant temperature bath, inner diameter 110 mm × depth 60 mm), the gap between the glass container and the sample container was filled with pure water, and the temperature of the pure water was made variable by an external heater. The temperatures of wax and pure water were measured using a radiation thermometer (trade name "IT-545", manufactured by HORIBA, Ltd.). A load (total amount 100 g) was applied to the needle, and the distance of the wax entering the wax vertically for 5 seconds was measured to calculate the degree of needle insertion. The types of wax are shown in Table 2.

<Reaction solution>
50 parts of malic acid, 10.0 parts of 2-pyrrolidone, 3.0 parts of potassium hydroxide, 3.5 parts of nonionic surfactant (trade name "acetylenol E60", manufactured by Kawaken Fine Chemicals), and ion-exchanged water 33. Five parts were mixed and sufficiently stirred to prepare a reaction solution.

<Ink>
(Preparation of pigment dispersion)
A styrene-ethyl acrylate-acrylic acid copolymer (resin 1) having an acid value of 150 mgKOH / g and a weight average molecular weight of 8,000 was prepared. After neutralizing 20.0 parts of resin 1 with potassium hydroxide having an acid value equal to the mole, an appropriate amount of pure water is added, and an aqueous solution of resin 1 having a resin (solid content) content of 20.0% is added. Was prepared. 10.0 parts of the pigment (carbon black), 15.0 parts of the aqueous solution of the resin 1 and 75.0 parts of pure water were mixed to obtain a mixture. The obtained mixture and 200 parts of 0.3 mm diameter zirconia beads were placed in a batch type vertical sand mill (manufactured by Imex) and dispersed for 5 hours while cooling with water. After centrifuging to remove coarse particles, pressure filtration is performed with a cellulose acetate filter (manufactured by Advantech) having a pore size of 3.0 μm, and the pigment content is 10.0% and the resin dispersant (resin 1) is contained. A pigment dispersion 1 having an amount of 3.0% was prepared.

(Preparation of resin particles)
In a four-necked flask equipped with a stirrer, a reflux cooling device, and a nitrogen gas introduction tube, 18.0 parts of butyl methacrylate, 2.0 parts of a polymerization initiator, and 2.0 parts of n-hexadecane were put into a nitrogen gas. The mixture was stirred for 0.5 hours while introducing. As the polymerization initiator, 2,2'-azobis (2-methylbutyronitrile) was used. Then, 78.0 parts of a 6.0% aqueous solution of an emulsifier (trade name “NIKKOL BC15”, manufactured by Nikko Chemicals Co., Ltd.) was added dropwise, and the mixture was stirred for 0.5 hours to obtain a mixture. After irradiating ultrasonic waves for 3 hours using an ultrasonic irradiator to emulsify the mixture, a polymerization reaction was carried out at 80 ° C. for 4 hours in a nitrogen atmosphere. After cooling to 25 ° C. and filtering, an appropriate amount of pure water was added to prepare an aqueous dispersion of resin particles having a resin particle (solid content) content of 40.0%.

(Ink preparation)
Each material was mixed according to the composition shown below, and after sufficient stirring, pressure filtration was performed with a cellulose acetate filter (manufactured by Advantech) having a pore size of 3.0 μm to prepare an ink (Bk ink).
-Pigment dispersion: 1: 40.0 parts-Water dispersion of resin particles: 20.0 parts-Glycerin: 7.0 parts-Acetyleneol E100: 0.5 parts-Ion-exchanged water: 32.5 parts

<Cleaning (CL) roller>
The types of cleaning rollers (CL rollers) shown in Table 3 were prepared.

<Combination of Examples and Comparative Examples>
An inkjet recording apparatus 100 (FIG. 1) in which the transfer bodies, waxes, and CL rollers of the types shown in Table 4 are combined was prepared. Then, the surface temperature (° C.) of the transfer body at the position "F" shown in Table 4, the temperature of the CL roller (° C.), the contact pressure between the CL roller and the transfer body (kgf / cm ² ), and the presence or absence of the cleaning liquid. Under the conditions, a solid image of 5 cm × 5 cm having a recording duty of 100% was recorded. In the case where the cleaning liquid was "Yes", the inkjet recording apparatus 200 having the configuration shown in FIG. 2 was used. The cleaning liquid storage unit 201 of the inkjet recording device 200 was filled with pure water. In the inkjet recording devices 100 and 200 used, an image recorded under the condition that one drop of 3.0 ng of ink is applied to a unit area of 1/1, 200 inch × 1/1, 200 inch has a recording duty of 100%. Is defined as.

<Evaluation>
(Cleanability)
The density value of the image recorded in the first lap and the density value of the image recorded in the tenth lap were measured, the difference between these values was calculated, and the cleanability was evaluated according to the evaluation criteria shown below. The density value (print density) of the image was measured using a fluorescence spectrophotometer (trade name "FD-7", manufactured by Konica Minolta). In the present invention, "AA" and "A" are set to an acceptable level, and "C" is set to an unacceptable level in the evaluation criteria shown below. The evaluation results are shown in Table 5.
AA: Concentration difference is less than 0.1 A: Concentration difference is 0.1 or more and less than 0.3 C: Concentration difference is 0.3 or more

100, 200 Inkjet recording device 101 Transfer member 102 Support member 103 Reaction liquid application device 104 Ink application device 105 Liquid removal device 106 Pressing member 107 Recording medium transfer device 108 Recording medium 109 Cleaning roller 110 Wax layer forming device 111 Transfer body cooling device 112 Transfer heating device 201 Cleaning liquid storage unit

Claims (7)

An inkjet recording method for recording an image on a recording medium using water-based ink.
The wax application process of applying wax to the transfer body and
A reaction solution applying step of applying a reaction solution containing a reactant that reacts with the aqueous ink to the transfer product, and a reaction solution application step.
An intermediate image forming step of applying the water-based ink to the transfer body to form an intermediate image,
A transfer step of bringing the intermediate image into contact with the recording medium and transferring the image,
A cleaning step of bringing the cleaning roller into contact with the transfer body to remove the wax residue on the transfer body is provided in this order.
The surface temperature of the transfer body in the cleaning step is at least a temperature at which the degree of needle insertion of the wax is 50 or more.
The surface free energy γ _CL (mN / m) of the _{cleaning roller, the surface tension γ W} (mN / m) of the _{wax, and the surface free energy γ T} (mN / m) of the _{transfer body are γ CL} > γ _W. An inkjet recording method characterized by satisfying the relationship of> γ _T. The inkjet recording method according to claim 1, wherein the temperature of the cleaning roller in the cleaning step is equal to or higher than a temperature at which the degree of needle insertion of the wax is 50 or more. The inkjet recording method according to claim 1 or 2, wherein the surface temperature of the transfer material in the cleaning step is equal to or higher than the melting point of the wax. The inkjet recording method according to any one of claims 1 to 3, wherein the temperature of the cleaning roller in the cleaning step is equal to or higher than the melting point of the wax. The inkjet recording according to any one of claims 1 to 4, wherein the surface free energy γ _CL (mN / m) of the _{cleaning roller is 10 mN / m or more higher than the surface tension γ W (mN / m) of the wax.} Method. The inkjet recording method according to any one of claims 1 to 5, wherein the contact pressure when the cleaning roller is brought into contact with the transfer body is 10 kgf / cm ^{2 or more.} The inkjet according to any one of claims 1 to 6, wherein the wax is at least one selected from the group consisting of microcrystalline wax, Fischer-Tropsch wax, polyolefin wax, paraffin wax, and modified products thereof. Recording method.

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