JP2023168784A - Inkjet recording method, and inkjet recording apparatus - Google Patents

Abstract

To excel in transferability of an image onto a recording medium even onto a transfer body generated with irregularity of a micron order, and suppress lowering of concentration and glossiness of an ink in a transferred image in a transfer type inkjet recording method.SOLUTION: An inkjet recording method includes: an image forming process (A) of forming an intermediate image on a transfer body including a wax-applying process, a reaction liquid-applying process, and an ink-applying process; a transfer process (B) of transferring the intermediate image to form a transfer image having a wax layer on a surface; and a heating process (C) of heating the transfer image by contacting or non-contacting to deform at least a part of the wax layer, where the wax has at least one melting point Tmr, a surface temperature Th of the wax layer of a transfer image in the heating process has a relation of Tmr≤Th with Tmr, and a pressure P1 when transferring in the process (B) and a pressure P2 when heating the transfer image by contacting in the process (C) has a relation of P1<P2.SELECTED DRAWING: Figure 1

Description

The present invention relates to an inkjet recording method and an inkjet recording apparatus.

In the inkjet recording method, a transfer type inkjet recording device is known, which forms an intermediate image by ejecting ink from an inkjet head onto the image forming surface of a transfer body, and transfers the intermediate image formed on the transfer body to a recording medium. ing.
In order to improve transfer efficiency, Patent Document 1 proposes a method in which an auxiliary liquid containing thermoplastic resin particles and rosin-based resin particles is applied onto ink and then transferred. Patent Document 2 proposes a method in which an ink containing a resin having a softening point is applied to a transfer body to form an ink image, the ink image is transferred to a recording medium, and the transferred image is heated and pressurized to fix it. There is.
Further, Patent Document 3 discloses, as a transfer-type inkjet recording method, that transferability is improved by applying wax to the surface of a transfer body before applying ink, and then applying ink. .

Japanese Patent Application Publication No. 2018-058354 JP2019-014244A Japanese Patent Application Publication No. 2021-194814

However, the transfer bodies used in Patent Documents 1 and 2 gradually deteriorate due to contact with a recording medium when transferring an image from the transfer body to a recording medium and contact with various members included in an inkjet recording apparatus. As a result of this deterioration, micron-order unevenness occurs on the surface of the transfer body, resulting in transfer failure and unevenness on the surface of the transferred image. Furthermore, if the transfer is defective, the ink density will decrease, and if the surface of the transferred image becomes uneven, the gloss will decrease.
Further, in the method described in Patent Document 3, wax is applied and then ink is applied to form an intermediate image on the transfer body. Then, after the formed intermediate image is transferred to a recording medium, a fixing member is brought into contact with the image to heat and fix it, thereby improving fixing performance. However, no consideration is given to the gloss or texture of the surface of the transferred image.

An object of the present invention is to provide an inkjet recording method that has excellent transfer properties even on a transfer material whose surface has irregularities on the order of microns, and that suppresses a decrease in ink density and a decrease in gloss of a transferred image. . Another object of the present invention is to provide an inkjet recording apparatus suitable for this inkjet recording method.

According to one aspect of the invention, the following steps (i) to (iii):
(i) a wax application step of applying wax onto the transfer body;
(ii) a reaction liquid applying step of applying a reaction liquid that reacts with the ink and thickens the ink onto the transfer body;
(iii) an ink application step of applying ink containing a coloring material onto the transfer body; an intermediate image forming step (A) of forming an intermediate image containing wax on the transfer body;
a transfer step (B) of bringing the intermediate image formed on the transfer body into contact with a recording medium and transferring it to the recording medium to form a transfer image including a wax layer on the surface;
a heating step (C) of heating the transferred image on the recording medium to deform at least a portion of the wax layer;
The wax has at least one melting point Tmr, and the temperature Th of the surface of the wax layer in the heating step (C) and the melting point Tmr have a relationship expressed by Formula 1-1,
Heating in the heating step (C) is performed without contacting or applying pressure to the transferred image,
The pressure P1 when transferring the intermediate image to the recording medium in the transfer step (B) and the pressure P2 when heating the transferred image while applying pressure in the heating step (C) are expressed by formula 1-2. Provided is an inkjet recording method characterized by having the relationship expressed;
Tmr≦Th (Formula 1-1)
P1<P2 (Formula 1-2).

According to another aspect of the present invention, there is provided a transfer type inkjet recording apparatus that forms an intermediate image on a transfer member and transfers the intermediate image onto a recording medium,
a wax application device that applies wax onto the transfer body;
a reaction liquid applying device that applies a reaction liquid that reacts with the ink and thickens the ink onto the transfer body;
an ink applying device that applies the ink containing a coloring material onto the transfer body using an inkjet method to form an intermediate image;
a transfer device that brings the intermediate image into contact with the recording medium together with the wax to transfer and form a transfer image including a wax layer on the surface;
a heating device that heats the wax layer of the transferred image,
The wax has at least one melting point Tmr, the heating device is a device that heats the surface of the wax layer at a temperature Th, and the Th and the melting point Tmr have a relationship expressed by Formula 1-1. has
The transfer device is a device that applies pressure P1 when transferring the intermediate image to a recording medium, and the heating device heats the transferred image without contact or while applying pressure P2. An inkjet recording apparatus is provided, wherein the P1 and the P2 have a relationship expressed by Formula 1-2;
Tmr≦Th (Formula 1-1)
P1<P2 (Formula 1-2).

According to the present invention, it is possible to provide an inkjet recording method that has excellent transferability and suppresses a decrease in ink density and a decrease in gloss of a transferred image. Further, according to the present invention, it is possible to provide an inkjet recording apparatus suitable for the above-mentioned inkjet recording method.

3 is a flowchart of an inkjet recording method according to the present invention. FIG. 3 is a conceptual diagram illustrating a step of heating a transferred image in an inkjet recording method according to an embodiment of the present invention. 1 is a schematic diagram showing an example of the configuration of a transfer type inkjet recording apparatus according to an embodiment of the present invention, and shows a configuration in which a wax layer is heated in a non-contact manner. FIG. 4 is a schematic diagram showing an example in which the heating of the wax layer in the transfer type inkjet recording apparatus shown in FIG. 3 is changed to a pressurizing method.

EMBODIMENT OF THE INVENTION Hereinafter, an inkjet recording method and an inkjet recording apparatus according to embodiments of the present invention will be described by citing preferred embodiments.
(Inkjet recording method)
As shown in the flowchart of FIG. 1, the inkjet recording method of the present invention comprises an intermediate image forming step (A) including (i) a wax application step, (ii) a reaction liquid application step, and (iii) an ink application step, It has a step (B) and a heating step (C) in this order. The intermediate image forming step (A) is a step of forming an intermediate image on the transfer body, the wax application step (i) is a step of applying wax on the transfer body, and the reaction liquid application step (ii) is a step of applying wax to the transfer body. This is a step of applying a reaction liquid that thickens the ink. The ink application step (iii) is a step of applying wax and a reaction liquid onto the transfer body and then applying ink containing a coloring material to form an ink image on the transfer body. In the intermediate image forming step (A), an intermediate image containing wax is formed. The transfer step (B) is a step in which the intermediate image containing wax formed in the intermediate image forming step (A) is brought into contact with a recording medium and transferred onto the recording medium to form a transferred image containing wax. The heating step (C) is a step of heating the transferred image containing the wax to partially deform the wax. Furthermore, it may include a cleaning step of cleaning the surface of the transfer body after the transfer. Furthermore, the intermediate image forming step (A) can include a liquid removal step for removing excess liquid components contained in the ink image. In this specification, an image from which the liquid has been removed and which is just before being transferred may be referred to as an "intermediate image", and an image containing ink before the liquid has been removed may be referred to as an "ink image".

The main structure and materials of the inkjet recording method according to the present invention will be explained below.
[A] Intermediate image forming step (i) Wax application step The wax applied onto the transfer body in the wax application step (i) of this embodiment has at least one melting point Tmr and may be a single compound. It may also be a mixture of wax materials having different melting points.
In a strict chemical sense, wax is an ester of fatty acids and water-insoluble higher monohydric alcohols or dihydric alcohols, and includes animal waxes and vegetable waxes, but does not include oils or fats. do not have. In a broad sense, it includes various wax formulations and modified products exemplified below. Specific examples of wax include natural waxes such as beeswax, lanolin, carnauba wax, candelilla wax, and montan wax; petroleum waxes such as paraffin wax and microcrystalline wax; Fischer-Tropsch wax, polyethylene wax, polypropylene wax, and oxidized wax. Modified waxes such as urethane-modified waxes and alcohol-modified waxes; α-olefin-maleic anhydride copolymer waxes and the like can be mentioned. These waxes may be used alone or in combination of two or more, if necessary.
Depending on the type of wax, it may contain solid components (impurities) that do not exhibit a melting point, but it is preferable to remove these in advance by melt filtration.
Furthermore, the wax in this embodiment preferably includes microcrystalline wax. Microcrystalline wax has a higher melting point than common paraffin wax, improving blocking performance at the same temperature. Further, for the same reason, it is preferable that Fischer-Tropsch wax is included. Furthermore, for the same reason, it is preferable that low density polyethylene wax is included. Since the low-density polyethylene wax has a high melting point, it is possible to increase the temperature difference between the lowest melting point Tmr1 and the highest melting point Tmr2 by combining it with other low-melting point wax components. That is, "at least one melting point Tmr" may be the lowest melting point Tmr1, the highest melting point Tmr2, or any melting point between them. In the heating step (C), the wax having a melting point Tmr1 is melted, but the wax having a melting point Tmr2 is not melted, so that it is possible to prevent the wax from melting completely and exposing the ink layer.
The wax is solid at room temperature (25°C), and the lowest melting point Tmr1 is preferably 40°C or higher, more preferably 50°C or higher. The same applies to waxes that have one melting point.
The melting point of wax can be measured according to the temperature measurement pattern of ASTM D3418. More specifically, the melting point of wax is measured using DSC-7 (PerkinElmer) at a heating rate of 10°C/min according to the temperature measurement pattern of ASTM D3418, and the melting point of the wax is determined by , the peak top at the lowest temperature is Tmr1, and the peak top at the highest temperature is Tmr2.
The wax may be applied by dissolving the wax itself, or by dissolving or dispersing the wax in a solvent, and then removing the solvent. Furthermore, even a method of adding and applying a wax component to the reaction liquid to be applied in the next reaction liquid applying step is treated as having a wax applying step in the present invention. Among these, it is preferable to melt the wax and apply the wax itself. In that case, the means for applying the wax may include a means for melting the wax and a means for applying the wax onto the transfer member.
The wax may be applied to the entire image forming area on the transfer body, or may be applied only to the area where the ink image is to be formed. Further, the thickness of the wax layer formed on the surface of the transfer body is preferably 0.1 μm or more and 10.0 μm or less, and more preferably 0.1 μm or more and 5.0 μm or less.

(ii) Reaction liquid application step The reaction liquid is a liquid that aggregates components having anionic groups (resin, self-dispersing pigment, etc.) in the ink when it comes into contact with the ink, and contains a reactant. Examples of the reactant include polyvalent metal ions, cationic components such as cationic resins, and organic acids.
Examples of polyvalent metal ions include divalent metal ions such as Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg 2+ , Sr ²⁺ , Ba ²⁺ , and Zn ^{2+ , Fe 3+ ,} Cr ³⁺ , Y ³⁺ , and ^{Al 3+} . Examples include trivalent metal ions. In order to contain polyvalent metal ions in the reaction solution, a polyvalent metal salt (which may be a hydrate) formed by combining a polyvalent metal ion and an anion can be used. Examples of anions include Cl ⁻ , Br ⁻ , I ^{− ,} ClO − , ClO ₂ ⁻ , ClO ₃ ⁻ , ClO ₄ ⁻ , NO ₂ ⁻ , NO ₃ ⁻ , SO ₄ ²⁻ , CO ₃ ²⁻ , HCO ₃ Inorganic anions such as ^- , PO ₄ ^3- , HPO ₄ ^2- , and H ₂ PO ₄ ^- ; 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 ^- . When a polyvalent metal ion is used as a reactant, the content (mass%) in terms of polyvalent metal salt 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. It is preferable that there be.
The reaction solution containing an organic acid has a buffering capacity in an acidic region (pH less than 7.0, preferably pH 2.0 to 5.0), so that it converts the anionic groups of the components present in the ink into acid form. It causes agglomeration. Examples of organic acids include formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrolecarboxylic acid, furancarboxylic acid, picolinic acid, nicotinic acid, thiophenecarboxylic acid, levulinic acid, coumaric acid, etc. monocarboxylic acids and their 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; Examples include salts and hydrogen salts; tricarboxylic acids such as citric acid and trimellitic acid, and their salts and hydrogen salts; tetracarboxylic acids such as pyromellitic acid, and their salts and hydrogen salts.
Examples of the cationic resin include resins having a primary to tertiary amine structure and resins having a quaternary ammonium salt structure. 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 reaction solution, a cationic resin and an acidic compound may be used together, or the cationic resin may be subjected to quaternization treatment. When using a cationic resin as a reactant, the content (mass%) of the cationic resin in the reaction solution should be 1.00% by mass or more and 10.00% by mass or less, based on the total mass of the reaction solution. preferable.
As components other than the reactant in the reaction solution, the same components as water, water-soluble organic solvents, and other additives that can be used in the ink described later can be used.

(iii) Ink application step Following the wax application step (i) and the reaction liquid application step (ii), the ink application step (iii) is performed. The ink to be applied includes at least a coloring material and a liquid for dissolving or dispersing the coloring material in order to eject the coloring material by an inkjet method. Preferably, the liquid is an aqueous medium. In addition, resin particles can be included.
Each component of the ink applied to this embodiment will be explained.

(color material)
Pigments and dyes can be used as the coloring material contained in the ink applied to this embodiment. 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 more preferable.
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; organic pigments such as azo-based, phthalocyanine-based, quinacridone, isoindolinone-based, imidazolone-based, diketopyrrolopyrrole-based, and dioxazine-based pigments. . These pigments can be used alone or in combination of two or more, if necessary. The pigment dispersion method is not particularly limited. For example, a resin-dispersed pigment dispersed with a resin dispersant, a self-dispersing pigment in which a hydrophilic group such as an anionic group is bonded to the particle surface of the pigment directly or through another atomic group, etc. can also be used. Of course, it is also possible to use a combination of pigments with different dispersion methods.
As the resin dispersant for dispersing the pigment, known resin dispersants used in aqueous inkjet inks can be used. Among these, in the aspect of this embodiment, it is preferable to use an acrylic water-soluble resin dispersant having both a hydrophilic unit and a hydrophobic unit in its 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 dissolved in the liquid medium, or may be dispersed as resin particles in the liquid medium. In the present invention, a resin being water-soluble 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 dynamic light scattering. do.

The hydrophilic unit (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 monomers having hydrophilic groups include acidic monomers having anionic groups 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 acidic monomer salt include ions such as lithium, sodium, potassium, ammonium, and organic ammonium.
The hydrophobic unit (unit without hydrophilicity such as an anionic group) can be formed, for example, by polymerizing a monomer having a hydrophobic group. Specific examples of monomers having hydrophobic groups include monomers having aromatic rings such as styrene, α-methylstyrene, benzyl (meth)acrylate; ethyl (meth)acrylate, methyl (meth)acrylate, butyl (meth)acrylate, etc. Examples include monomers having an aliphatic group (ie, (meth)acrylic ester monomers).

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. Further, the weight average molecular weight of the resin dispersant is preferably 1,000 or more and 50,000 or less. It is preferable that the pigment content (mass %) is 0.3 times or more and 10.0 times or less as a mass ratio (pigment/resin dispersant) to the resin dispersant content.
As a self-dispersing pigment, one in which an anionic group such as a carboxylic acid group, a sulfonic acid group, or a phosphonic acid group is bonded to the particle surface of the pigment directly or through another atomic group (-R-) is used. be able to. The anionic group may be either an acid type or a salt type, and when it is a salt type, it may be either partially or completely dissociated. Examples of cations that serve as counter ions when the anionic group is a salt type include alkali metal cations; ammonium; organic ammonium; and the like. Specific examples of other atomic groups (-R-) include linear or branched alkylene groups having 1 to 12 carbon atoms, arylene groups such as phenylene groups and naphthylene groups, amide groups, sulfonyl groups, and amino groups. , carbonyl group, ester group, ether group, etc. Alternatively, a combination of these groups may be used.

Although the type of dye that can be used as the coloring material is not particularly limited, it is preferable to use a dye having an anionic group. Specific examples of dyes include azo dyes, triphenylmethane dyes, (aza)phthalocyanine dyes, xanthene dyes, and anthrapyridone dyes. These dyes can be used alone or in combination of two or more, if necessary.
Furthermore, it is also suitable in this embodiment to use a so-called self-dispersing pigment, which is made dispersible by surface modification of the pigment itself, without using a dispersant.

(resin particles)
The ink applied to this embodiment can contain resin particles. The resin particles do not need to contain a coloring material. Resin particles are suitable because they may be effective in improving image quality and fixing properties.
The material of the resin particles that can be used in this embodiment is not particularly limited, and any known resin 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 mentioned. The weight average molecular weight (Mw) of the resin particles is preferably in the range of 1,000 or more and 2,000,000 or less. The volume average particle diameter of the resin particles measured by a 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 resin particles in the ink is preferably 1.0% by mass or more and 50.0% by mass or less, more preferably 2.0% by mass or more and 40.0% by mass, based on the total mass of the ink. It is as follows.

(aqueous medium)
The ink that can be used in this embodiment can contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. As water, it is preferable to use deionized water or ion-exchanged water. The water content (mass%) in the aqueous ink is preferably 50.0% by mass or more and 95.0% by mass or less, based on the total mass of the ink. Further, the content (mass%) of the water-soluble organic solvent in the water-based 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 solvent that can be used in inkjet inks, such as alcohols, (poly)alkylene glycols, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds, can be used. A species or two or more species can be included.

(Other additives)
In addition to the above-mentioned components, the ink that can be used in this embodiment may include an antifoaming agent, a surfactant, a pH adjuster, a viscosity adjuster, a rust preventive, a preservative, an antifungal agent, an oxidizing agent, etc. It may contain various additives such as inhibitors, reduction inhibitors, and water-soluble resins.
The softening point of the resin of the ink can be measured according to JIS K 6828-2 "How to determine the minimum film forming temperature". More specifically, the resin dispersion was heated under an appropriate temperature gradient, and the boundary temperature between the transparent part where the film was formed and the part where the film was not formed was measured.

(iv) Auxiliary liquid application step An auxiliary liquid, which is a transfer assisting liquid containing a thermoplastic resin that becomes a binder in the ink image, may be applied onto the transfer body. This improves the transferability to the recording medium. The auxiliary liquid may be either aqueous or non-aqueous, but preferably is aqueous and contains a water-soluble thermoplastic resin.

(v) Liquid Removal Step The intermediate image forming step (A) of this embodiment can include a liquid removal step. As a method for excluding the liquid, various conventional methods can be used, such as a heating method, a method of blowing low-humidity air, a method of reducing the pressure, and the like.
In addition to the above-mentioned method, a method of absorbing liquid by pressing a liquid absorbing member including a porous body against the liquid absorbing member can also be used. At this time, it is particularly preferable that the liquid absorbing member be pressed against the transfer body with a predetermined pressing force in the state in which the liquid absorbing member is in contact with the transferring body, since this allows the liquid absorbing member to function effectively.
If the removal of the liquid component by contact with the liquid absorbing member is explained from a different perspective, it can also be expressed as concentrating the ink constituting the image formed on the transfer body. Concentrating the ink means that the liquid component contained in the ink decreases, thereby increasing the content ratio of solids such as coloring materials and resins contained in the ink to the liquid component.
In addition, in this embodiment, since the image is formed by applying the reaction liquid onto the transfer body and then applying the ink, the reaction liquid does not react with the ink in the non-image area where the image with the ink is not formed. Remaining.
Removal of the liquid component by contact with the liquid absorbing member is expressed and explained as removing the liquid component from the image, but this does not mean in a limited sense that the liquid component is removed only from the image, but at least from the image on the transfer body. It is used to mean that it is sufficient to remove liquid components.
Note that the liquid component is not particularly limited as long as it does not have a fixed shape, has fluidity, and has a substantially constant volume. Examples of liquid components include water, organic solvents, and the like contained in ink and reaction liquid.

[B] Transfer step Through the above intermediate image forming step (A), an intermediate image containing wax is formed on the transfer body. This intermediate image is then transferred to a recording medium. During the transfer, in order to peel off the intermediate image formed on the transfer body, heating is performed at a temperature equal to or higher than the melting point of the formed wax layer, and pressure is applied from the opposite side of the recording medium to the transfer body. The pressing method is not particularly limited, and any method that can apply the pressure and temperature necessary for transfer can be used, and a member that presses from the opposite side of the recording medium to the side facing the transfer body is used. Hereinafter, it may be referred to as a pressing member. In consideration of transferability, the pressing member is preferably a rotating body that follows the rotation of the transfer body.
The heating temperature at the time of transfer is higher than the melting point of the formed wax layer, and when waxes of multiple materials with different melting points are used, it is preferable to set the temperature to higher than the highest melting point Tmr2. By setting the temperature to be above the melting point of the wax, at least a portion of the wax melts, thereby improving mold releasability and improving transferability. Even on a transfer body that has deteriorated and has micron-order irregularities on its surface, the transfer properties are good. On the other hand, the wax that has entered the unevenness may be transferred as it is or partially onto the surface of the transferred image, resulting in deterioration of the surface quality of the transferred image.
When the ink contains a resin component, the temperature of the intermediate image during transfer is preferably equal to or higher than the glass transition point or softening point (referred to as Tsi) of the resin component contained.
Specifically, the temperature of the intermediate image during transfer is preferably 60°C or more and 140°C or less, more preferably 70°C or more and 120°C or less. At this time, the temperature of the intermediate image can be measured using a non-contact thermometer or the like.

[C] Heating process The wax layer that was in contact with the transfer body becomes the surface of the transferred image transferred onto the recording medium.
FIG. 2 is a conceptual diagram illustrating the heating step of the inkjet recording method of this embodiment.
As shown in FIG. 2(a), the image transferred to the recording medium 23 has an ink layer 22 and a wax layer 21 on its surface, and has micron-order convexities due to irregularities on the transfer body due to deterioration etc. A portion 24 or a recess 25 may occur. Since the wax layer 21 has a certain thickness, the convex portions 24 and concave portions 25 do not propagate in the ink layer 22. In this embodiment, as shown in FIG. 2(b), heating processing 26 is performed from the surface side of the wax layer 21 to deform a part of the wax layer 21, especially the generated convex portions 24 and concave portions 25, and to reduce the unevenness. It is being reduced.
In this embodiment, when the wax has at least one melting point Tmr and the heating temperature of the transferred image in the heating step (C) is Th, the following formula 1-1 is satisfied.
Further, the heating in the heating step (C) is performed without contacting the transferred image or while applying pressure,
When the pressure P1 when transferring the intermediate image to the recording medium in the transfer step (B) and the pressure P2 when heating the transferred image while applying pressure in the heating step (C), the following formula 1- 2 is satisfied;
Tmr≦Th (Formula 1-1)
P1<P2 (Formula 1-2).
When the above formula 1-1 is satisfied, at least a portion of the wax layer 21 of the transferred image on the recording medium 23 is melted by the heating process 26, and the convex portions 24 and concave portions 25 of the micron order on the wax layer 21 of the transferred image are melted. (FIG. 2(a)) can be made smooth (FIG. 2(b)). The heating temperature Th indicates the temperature of the surface of the transferred image, that is, the surface of the wax layer 21. In addition, in the present disclosure, the inventors believe that the reason why it is necessary to satisfy the above formula 1-2 is as follows. In the transfer step (B), there is no need to smooth the surface of the intermediate image, and if the wax is melted to some extent, transfer can be performed even with a small amount of pressure. On the other hand, in the heating step (C), it is preferable to melt the wax and apply pressure to the surface of the transferred image to smooth it. The pressure P2 for smoothing in the heating step (C) needs to be higher than the pressure P1 used when transferring the intermediate image to the recording medium in the transfer step (B).
Non-contact heating is performed when it is desired to reflect the texture of the surface of the recording medium. If the recording medium is a medium with unevenness such as matte paper, the feel of the recording medium itself may be impaired if pressure is applied to flatten the medium. Non-contact heating melts the wax layer that has been partially flattened during transfer, and the wax moves to follow the large irregularities of the base, resulting in an image that takes advantage of the texture of the recording medium.

Further, when the ink contains a resin component, for example, when the above-mentioned clear ink is used, the resin component contained in the ink layer 22 has a glass transition point or a softening point Tsi, and the heating temperature Th is determined by the above formula 1. In addition to -1, it is preferable to satisfy the following formula 2;
Tmr≦Th<Tsi (Formula 2).
When smoothing the convex portions 24 and concave portions 25 on the surface of the wax layer 21, if the surface unevenness on the wax layer 21 of the transferred image is large, the ink layer 22 may move and the ink density around the relevant portion may decrease. be. Therefore, when the above formula 2 is satisfied, this phenomenon can be prevented.
Here, when using ink of multiple colors such as cyan, magenta, yellow, and black (CMYK), Tsi of the resin contained in the ink means the glass transition point or softening point of the lowest temperature among the multiple colors. do.

Furthermore, the wax of this embodiment may be composed of a mixture of multiple materials having different melting points. At this time, the at least one melting point Tmr of the wax may be the melting point of any material in the mixture, and may be the lowest melting point Tmr1, the highest melting point Tmr2, or a melting point between them. That is, the heating temperature Th of the transferred image in the heating step (C) and the lowest melting point Tmr1 of the melting points of the plural wax materials satisfy the following formula 3;
Tmr1≦Th (Formula 3).
Further, it is preferable that the glass transition point or softening point Ts1 of the resin component contained in the ink satisfies the following formula 4 in addition to the above formula 3;
Tmr1≦Th<Tsi (Formula 4).
When the above formula 4 is satisfied, only the material whose heating temperature Th exceeds the melting point of the wax material of the transferred image is melted, and it is possible to smooth the micron-order unevenness on the wax of the transferred image.

On the other hand, in the present invention, it is more preferable that the highest melting point Tmr2 among the melting points of the plurality of wax materials satisfies Expression 5. If the wax layer on the transferred image completely melts in the thickness direction, the wax may move due to the protrusions of the recording medium or the means that applies pressure, causing the ink layer to be partially exposed and the texture to change. be. By satisfying Equation 5, this phenomenon can be prevented.
Th<Tmr2 (Equation 5).
Note that Tmr2 is preferably lower than Ts1 of the resin component contained in the above-mentioned ink, and more preferably lower than Tsi. That is, it is preferable that Tsi, temperature Th, and melting point Tmr2 of the resin satisfy the relationship expressed by Formula 6 below.
Th<Tmr2≦Tsi (Formula 6).
In the heating step (C), it is important that the heating temperature Th satisfies the above formulas 1-1 and 2 to 6, and is preferably 50° C. or more and 140° C. or less.
In this heating step (C), a method of deforming only the convex portions 24 and concave portions 25 from the surface of the wax layer 21 without contacting the surface of the wax layer 21 can be preferably used. If heating is applied from the recording medium side, the thermal load on the ink layer 22 becomes too large, which may damage the ink layer, and it is particularly difficult to achieve the above formulas 2, 4, and 6. In the case of such non-contact heating, it is possible to move the wax that has not been completely transferred during transfer. Furthermore, even for recording media with large surface irregularities of several tens of micrometers or more, by heating without contact, only the micron-order irregularities on the wax surface are smoothed out, leaving a natural texture.
Furthermore, in order to more gently deform the irregularities on the surface of the wax layer 21, a method may be used in which the surface of the wax layer 21 is brought into contact and heated. It is important that the pressure applied at this time be higher than the pressure applied during the transfer step.

(Inkjet recording device)
As the inkjet recording apparatus according to the present invention, any apparatus that can carry out the above inkjet recording method can be used. Since it uses a transfer body, it is conveniently referred to as a transfer type inkjet recording device. An example of a transfer type inkjet recording device is a transfer type inkjet recording device in which an ink image is formed by ejecting ink onto a transfer body, and the ink image after liquid absorption from the ink image by a liquid absorption member is transferred to a recording medium. explain.

FIG. 3 is a schematic diagram showing an example of a schematic configuration of the transfer type inkjet recording apparatus 100 of this embodiment. This recording apparatus is a sheet-fed inkjet recording apparatus that produces a recorded matter by transferring an ink image onto a recording medium 108 via a transfer body 101. In this embodiment, the X direction, Y direction, and Z direction indicate the width direction (total length direction), depth direction, and height direction of the transfer type inkjet recording apparatus 100, respectively. The recording medium 108 is conveyed in the X direction.
The transfer type inkjet recording apparatus 100 of the present invention has a transfer body 101 supported by a support member 102, as shown in FIG. It has a wax application device 110 that applies wax for improving transferability onto the transfer body 101, and a reaction liquid application device 103 that applies a reaction liquid that reacts with the ink. The apparatus also includes an ink applying device 104 equipped with an inkjet head that applies colored ink onto the transfer body 101 to which the reaction liquid has been applied and forms an ink image (intermediate image) on the transfer body. The ink applying device 104 may apply a transfer auxiliary liquid as necessary. Furthermore, this embodiment includes a liquid removal device 105 that removes liquid components from the intermediate image on the transfer body. In this way, the intermediate image forming step (A) is performed. Furthermore, this recording apparatus 100 includes a transfer device for transferring the intermediate image formed on the transfer body in this manner onto a recording medium 108 such as paper. The transfer device includes a pressure member 106 for transfer and a conveyance device 107 for a recording medium 108. The transferred image containing wax transferred onto the recording medium 108 is heated by a heating device 111 that deforms a portion of the wax. Further, the transfer type inkjet recording apparatus 100 may include a transfer member cleaning member 109 that cleans the surface of the transfer member 101 after the transfer, if necessary. The transfer body 101, the reaction liquid applying device 103, the inkjet head of the ink applying device 104, the liquid removing device 105, the transfer body cleaning member 109, and the heating device 111 each have a size corresponding to the recording medium 108 used in the Y direction. It has a length.

The transfer body 101 rotates in the direction of arrow A in FIG. 3 about the rotation axis 102a of the support member 102. Due to this rotation of the support member 102, the image forming area of the transfer body 101 is sequentially moved. A wax forming device 110 applies wax, a reaction liquid applying device 103 applies a reaction liquid, and an ink applying device 104 applies ink to a moving image forming area on the transfer body 101 in this order. In this way, an ink image including a wax layer is formed in the image forming area on the transfer body 101. The ink image formed on the transfer body 101 is moved to the liquid removal device 105 by movement of the image forming area. The length of the image forming area varies depending on the length of the image transferred onto the recording medium in the X direction, but at the longest, the image forming area extends from the time of wax application by the wax forming device 110 to the time of transfer by the transfer unit 115. is the length in the circumferential direction.
Then, the ink image after liquid removal (referred to as an intermediate image) from which the liquid component has been removed by the liquid removal device 105 has a state in which the ink is concentrated compared to the ink image before liquid removal. Further, the transfer body 101 moves the recording medium 108 to a transfer unit 115 where it comes into contact with the recording medium 108 conveyed by the recording medium conveying device 107 . While the intermediate image is in contact with the recording medium 108, the pressing member 106 presses the transfer body 101, thereby transferring the intermediate image onto the recording medium 108. At this time, the presence of wax makes it easier for the intermediate image to peel off from the transfer body 101. The transferred image transferred onto the recording medium 108 is a reversed image of the ink image before liquid removal and the intermediate image after liquid removal, and becomes a transferred image containing wax on the side opposite to the surface facing the recording medium. .
Next, a heating device 111, which is a characteristic feature of the present invention, heats the transferred image containing wax to partially deform the wax.
Note that the liquid component is not particularly limited as long as it does not have a fixed shape, has fluidity, and has a substantially constant volume. Examples of liquid components include water, organic solvents, and the like contained in ink and reaction liquid.

The main components of the transfer type inkjet recording apparatus 100 will be explained below.
[1] Transfer body The transfer body 101 has a surface layer including an image forming surface. Various materials such as resins and ceramics can be used as appropriate for the surface layer member, but materials with high compressive elastic modulus are preferred from the viewpoint of durability and the like. Furthermore, in order to improve the transferability of the intermediate image to the recording medium, it is preferable that the material is made of a material that has low affinity with the wax that functions as a release layer. Specific examples include condensates obtained by condensing acrylic resins, acrylic silicone resins, fluorine-containing resins, and hydrolyzable organosilicon compounds. In order to improve the wettability, transferability, etc. of the reaction solution, it may be used after surface treatment. Examples of the surface treatment include flame treatment, corona treatment, plasma treatment, polishing treatment, roughening treatment, active energy ray irradiation treatment, ozone treatment, surfactant treatment, silane coupling treatment, and the like. A plurality of these may be combined. Further, the surface layer can be provided with any surface shape in order to improve the retention of wax or ink as long as it does not affect the transferred image.

Further, it is preferable that the transfer body 101 has a compression layer having a function of absorbing pressure fluctuations. By providing the compressed layer, the compressed layer absorbs deformation, disperses local pressure fluctuations, and maintains good transferability even during high-speed printing. Examples of the material for the compression layer include acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, and silicone rubber. When molding the rubber material, it is preferable that a predetermined amount of a vulcanizing agent, a vulcanization accelerator, etc. be blended therein, and further a blowing agent, a filler such as hollow fine particles or common salt may be blended as needed to make it porous. As a result, the bubble portion is compressed with a change in volume in response to various pressure fluctuations, so deformation in directions other than the compression direction is small, and more stable transferability and durability can be obtained. Porous rubber materials include those with a continuous pore structure in which each pore is continuous with each other and those with an independent pore structure in which each pore is independent. In the present invention, any structure may be used, and these structures may be used in combination.

Furthermore, it is preferable that the transfer body 101 has an elastic layer between the surface layer and the compressed layer. As the member of the elastic layer, various materials such as resin and ceramic can be used as appropriate. Various elastomer materials and rubber materials are preferably used in terms of processing characteristics and the like. Specifically, examples include fluorosilicone rubber, phenyl silicone rubber, fluororubber, chloroprene rubber, urethane rubber, nitrile rubber, ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber, and ethylene/propylene/butadiene copolymer. Examples include rubber, nitrile butadiene rubber, and the like. In particular, silicone rubber, fluorosilicone rubber, and phenyl silicone rubber are preferable in terms of dimensional stability and durability because of their small compression set. Further, the change in elastic modulus due to temperature is small, which is preferable in terms of transferability.
Various adhesives or double-sided tapes may be used between the layers (surface layer, elastic layer, compression layer) constituting the transfer body 101 to fix and hold them. Further, a reinforcing layer having a high compressive elastic modulus may be provided to suppress lateral elongation and maintain stiffness when attached to a device. Further, a woven fabric may be used as a reinforcing layer. The transfer body can be manufactured by arbitrarily combining layers made of the above-mentioned materials.
The size of the transfer body can be freely selected according to the desired print image size. The shape of the transfer body is not particularly limited, and specific examples thereof include a sheet shape, a roller shape, a belt shape, an endless web shape, and the like.

[2] Support member The transfer body 101 is supported on the support member 102. Various adhesives or double-sided tapes may be used to support the transfer body. Alternatively, by attaching an installation member made of metal, ceramic, resin, or the like to the transfer body, the transfer body may be supported on the support member 102 using the installation member.
The support member 102 is required to have a certain degree of structural strength from the viewpoint of transportation accuracy and durability. As the material of the support member 102, metal, ceramic, resin, etc. are preferably used. In particular, we use aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, Polyethylene, polyethylene terephthalate, nylon, polyurethane, silica ceramics, and alumina ceramics are preferably used. It is also preferable to use these in combination.

[3] Wax Application Device The transfer type inkjet recording device 100 of this embodiment includes a wax application device 110 that forms a wax layer on the transfer body 101. The wax application device 110 in FIG. 3 shows a wax storage section 110a that stores wax, and wax application members 110b and 110c that apply the wax in the wax storage section 110a onto the transfer body 101.
The wax application device 110 may be any device that can apply wax onto the transfer body, and various conventionally known devices can be used as appropriate. Specifically, examples include a gravure offset roller, an inkjet head, a die coating device (die coater), a blade coating device (blade coater), and the like.
The wax is preferably applied in a molten state, and by keeping the temperature of the transfer body below the melting point of the wax when applying the wax, it is possible to form a thin layer while solidifying the wax.
The area to which the wax is applied does not need to be the entire width of the transfer body 101 in the Y direction, but may be approximately the width of the recording medium to which the wax is transferred.

[4] Reaction Liquid Applying Device The transfer type inkjet recording apparatus 100 of this embodiment includes a reaction liquid applying device 103 that applies a reaction liquid to the transfer body 101. The reaction liquid application device 103 in FIG. 3 includes a gravure offset roller having a reaction liquid storage part 103a for storing a reaction liquid, and reaction liquid application members 103b and 103c for applying the reaction liquid in the reaction liquid storage part 103a onto the transfer body 101. The case is shown below.
The reaction liquid applying device 103 may be any device capable of applying a reaction liquid onto the transfer body, and various conventionally known devices can be used as appropriate. Specifically, examples include a gravure offset roller, an inkjet head, a die coating device (die coater), a blade coating device (blade coater), and the like. Application of the reaction liquid by the reaction liquid application device may be performed before or after application of the ink, as long as it can be mixed (reacted) with the ink on the transfer body. Preferably, the reaction liquid is applied before the ink is applied. By applying the reaction liquid before applying the ink, during image recording using the inkjet method, problems such as bleeding, where adjacently applied inks mix with each other, and ink that lands first being attracted to ink that lands later, can be avoided. It is also possible to suppress dings.

[5] Ink application device The transfer type inkjet recording device 100 of this embodiment includes an ink application device 104 that applies ink to the transfer body 101. The reaction liquid and ink are mixed on the transfer body, and an ink image is formed by the reaction liquid and ink.
In this embodiment, an inkjet head is used as the ink applying device 104 that applies ink. Inkjet heads include, for example, a type that ejects ink by causing film boiling in the ink to form bubbles using an electro-thermal converter, a type that ejects ink using an electro-mechanical converter, and a type that ejects ink using static electricity. Examples include a form of ejection. In this embodiment, a known inkjet head can be used. Among these, from the viewpoint of high-speed, high-density printing, those using an electrothermal converter are preferably used. For drawing, an image signal is received and the necessary amount of ink is applied to each position.
In this embodiment, the inkjet head is a full-line head extending in the Y direction, and the nozzles are arranged in a range that covers the width of the image recording area of the largest usable recording medium. The inkjet head has an ink ejection surface with nozzles opened on its lower surface (transfer body 101 side), and the ink ejection surface faces the surface of the transfer body 101 with a small gap (about several millimeters) left there. .
The amount of ink applied can be expressed by image density (duty) or ink thickness, but in this embodiment, the mass of each ink dot is multiplied by the number of applied ink dots, and the average value divided by the printing area is calculated as the amount of ink applied (g/ ^m2 ). Note that the maximum amount of ink applied in the image area refers to the amount of ink applied in an area of at least 5 mm ² or more in the area used as information on the ejection target medium, from the perspective of removing liquid components in the ink. show.

The ink application device 104 may have a plurality of inkjet heads in order to apply color ink of each color onto the transfer body. For example, when forming images of each color using yellow ink, magenta ink, cyan ink, and black ink, the ink applying device has four inkjet heads that respectively eject the four types of ink onto the transfer body. Then, these are arranged so as to be lined up in the X direction.
Further, the ink applying device 104 may include an inkjet head that does not contain a coloring material, or even if it does contain a coloring material, the proportion thereof is very low and that discharges substantially transparent clear ink. This clear ink can be used together with the reaction liquid and color ink to form an ink image. For example, this clear ink can be used to improve the gloss of an image. It is preferable to appropriately adjust the blended resin components and further control the ejection position of the clear ink so that the image after transfer has a glossy appearance. It is preferable for this clear ink to be on the surface layer (surface) side of the transferred image transferred onto the recording medium than the color ink, so the clear ink is applied to the transfer body 101 before the color ink. . Therefore, in the moving direction of the transfer body 101 facing the ink applying device 104, the inkjet head for clear ink can be arranged upstream of the inkjet head for color ink.
Furthermore, in the present invention, clear ink can be used in addition to gloss ink to improve the transferability of images from the transfer body 101 to the recording medium. For example, a clear ink can be used as a transferability improving liquid to be applied onto the transfer body 101 by containing a larger amount of a component that exhibits tackiness than the color ink and applying this to the color ink. For example, in the moving direction of the transfer body 101 facing the ink applying device 104, an inkjet head for clear ink for improving transferability is arranged downstream from an inkjet head for color ink. Then, after color ink is applied to the transfer body 101, clear ink is applied on the transfer body after the color ink has been applied, so that the clear ink is present on the outermost surface of the ink image. During the transfer of the intermediate image to the recording medium in the transfer unit 115, the clear ink on the outermost surface adheres to the recording medium 108 with a certain degree of adhesive force, which makes it easier for the intermediate image to move to the recording medium 108 after the liquid is removed. Become.

[6] Liquid Removal Device The liquid removal device 105 can remove the liquid by using various conventional methods, such as heating, blowing low-humidity air, and reducing pressure. When using a heating method, it is preferable to use an infrared heater because it can heat efficiently in a short time.
In addition to the above-mentioned method, a method of absorbing liquid by pressing a liquid absorbing member including a porous body against the liquid absorbing member can also be used. At this time, it is particularly preferable that the liquid absorbing member be pressed against the transfer body 101 with a predetermined pressing force in a state in which the liquid absorbing member is in contact with the transfer body 101 in order to make the liquid absorbing member function effectively. The pressing force of the liquid absorbing member is not particularly limited as long as it can absorb the liquid in the ink image.
If the removal of the liquid component by contact with the liquid absorbing member is explained from a different perspective, it can also be expressed as concentrating the ink constituting the image formed on the transfer body. Concentrating the ink means that the liquid component contained in the ink decreases, thereby increasing the content ratio of solids such as coloring materials and resins contained in the ink to the liquid component.
When a heating method is used in the liquid removal device 105, it can also be used to adjust the temperature to a temperature suitable for melting at least a portion of the wax when transferring an intermediate image to a recording medium. In the case of a means for absorbing liquid by pressing a liquid absorbing member including a porous body against the liquid absorbing member, the liquid absorbing member that contacts the liquid absorbing member and reduces the amount of the liquid component of the ink image is included. The liquid absorbing member may be formed on the outer peripheral surface of the roller, or the liquid absorbing member may be formed in the form of an endless sheet and run in a circular manner. In order to protect the image, the moving speed of the liquid absorbing member may be synchronized with the circumferential speed of the transfer body and the speed of the liquid absorbing member.

The liquid absorbing member may include a porous body that contacts the ink image. In order to suppress adhesion of ink solid content to the liquid absorbing member, the pore diameter of the porous body on the surface that contacts the ink image may be 10 μm or less. Here, the pore diameter refers to the average diameter, and can be measured by known means such as mercury intrusion method, nitrogen adsorption method, and SEM image observation.
In this way, an intermediate image is formed on the transfer body 101 in which the liquid component is removed from the ink image or the liquid component is reduced. The intermediate image after this liquid is removed is then transferred onto the recording medium 108 in the transfer section 115.

[7] Transfer Device In the transfer type inkjet recording device 100 of the present embodiment, a transfer device for transferring an intermediate image onto a recording medium 108 has a pressing member 106 that faces the transfer body 101 and presses the transfer body 101. have A nip portion formed by the contact between the transfer body 101 and the pressing member 106 is referred to as a transfer portion 115, and as the recording medium 108 passes through the transfer portion 115, the intermediate image on the transfer body is transferred onto the recording medium. . Further, a conveying device 107 that conveys the recording medium 108 is also considered as a part of the transfer device.

7a. Pressing Member In this embodiment, the intermediate image after the liquid removal on the transfer body 101 is transferred onto the recording medium 108 conveyed by the recording medium conveying means 107 by contacting the recording medium 108 with the pressing member 106 for transfer. do. By removing the liquid component contained in the ink image on the transfer body 101 and then transferring it to the recording medium 108, it is possible to obtain a recorded image with suppressed curls, cockling, and the like.
The pressing member 106 is required to have a certain degree of structural strength from the viewpoint of conveyance accuracy and durability of the recording medium 108. The material of the pressing member 106 is preferably metal, ceramic, resin, or the like. In particular, we use aluminum, iron, stainless steel, acetal resin, epoxy resin, polyimide, Polyethylene, polyethylene terephthalate, nylon, polyurethane, silica ceramics, and alumina ceramics are preferably used. Moreover, you may use these in combination.
There is no particular restriction on the pressing time during which the pressing member 106 presses the transfer body in order to transfer the intermediate image after the liquid has been removed from the transfer body 101 onto the recording medium 108 . However, in order to perform the transfer well and not to impair the durability of the transfer body, the time period is preferably 5 ms or more and 100 ms or less. Note that the pressing time in this embodiment refers to the time during which the recording medium 108 and the transfer body 101 are in contact, and is measured using a surface pressure distribution measuring device ("I-SCAN", trade name of Nittasha). The value was calculated by measuring the surface pressure by dividing the length of the pressurized area in the conveyance direction by the conveyance speed.
Further, there is no particular restriction on the pressure with which the pressing member 106 presses the transfer body 101 in order to transfer the intermediate image after the liquid has been removed from the transfer body 101 onto the recording medium 108. Avoid compromising the durability of your body. For this reason, the pressure 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. Note that the pressure in this embodiment refers to the nip pressure between the recording medium 108 and the transfer body 101, and the surface pressure is measured using a surface pressure distribution measuring device, and the load in the pressure area is divided by the area. This is the calculated value.

The temperature of the intermediate image when the pressing member 106 presses the transfer body 101 in order to transfer the intermediate image after the liquid has been removed from the transfer body 101 to the recording medium 108 is the temperature explained in the transfer step (B) above. . At this time, the temperature of the intermediate image layer can be measured using an infrared radiation thermometer.
By being equal to or higher than Tsi of the resin component contained in the ink, the adhesion between the recording medium and the transferred image is improved. The melting point (Tmr) of the wax is preferably Tsi or lower, and the highest melting point Tmr2 of the wax is preferably Tsi or lower.
Further, a preferred embodiment includes a heating means for heating the intermediate image on the transfer body 101, the transfer body 101, and the recording medium 108 for heating. Further, a heating means may be provided in the pressing member 106 so that the heating temperature on the recording medium is higher than the heating temperature on the transfer body. By heating from the recording medium side, even if the melting point Tmr of the wax is lower than Tsi and the difference therebetween is large, excessive heating of the wax layer can be suppressed.
Although the shape of the pressing member 106 is not particularly limited, it may have a roller shape, for example.

7b. Conveying Device The conveying device 107 for conveying the recording medium 108 is composed of a recording medium feeding roller 107a and a recording medium take-up roller 107b, but it is sufficient that it can convey the recording medium 108, and the configuration is not particularly limited to this. isn't it.

[8] Recording Medium In this embodiment, the recording medium 108 is not particularly limited, and any known recording medium can be used. Examples of the recording medium include a long material wound into a roll or a sheet material cut into a predetermined size. Examples of the material include paper, plastic film, wood board, cardboard, and metal film.

[9] Heating Device In this embodiment, the heating device 111 heats the transferred image, which has wax on the surface, and is transferred onto the recording medium 108 that is transported by the recording medium transport means 107. Transform some parts.
The heating device 111 may be any device as long as it can heat the transferred image to the temperature Th explained in the heating step (C) above. For example, a non-contact heating device 111a as shown in FIG. , infrared heaters or hot air). The heating time and the distance between the non-contact heating device 111a and the transferred image are not particularly limited as long as the wax can be melted and micron-order unevenness on the wax can be smoothed.
Furthermore, as the heating device 111 of this embodiment, there is a method of heating while applying pressure with rollers 111b and 111c (FIG. 4(a)), or a method of heating while applying pressure with belts 111d and 111e (FIG. 4(a)). b)) is preferred. At this time, heating is performed using the roller 111b or the belt 111d. The pressing time and the nip width of the roller or belt are not particularly limited as long as the wax is melted and the micron-order irregularities on the wax are smoothed. At this time, the pressure applied by the roller or belt is set to be greater than the pressure applied by the pressing member 106 against the transfer member 101 . Since the wax in the transferred image can be forcibly flattened using a roller or belt, an image with high gloss can be obtained. The pressing force is preferably 9.8 N/cm ² (1 kg/cm ² ) or more and 196.0 N/cm ² (20 kg/cm ² ) or less.
The material used for the roller 111b and the belt 111d is a material that has low affinity with wax because it comes into contact with the wax, and any material with a smooth surface can be used.
The heating temperature of the transferred image can be measured by installing a non-contact thermometer 114 at a position where the image can be measured immediately after heating.

Hereinafter, this embodiment will be described in more detail using Examples and Comparative Examples. The present invention is not limited in any way by the following examples unless it exceeds the gist thereof. In the following description of Examples, "parts" and "%" regarding quantitative ratios are based on mass unless otherwise specified.

<Transfer body>
The transfer body 101 was fixed to the surface of the support member 102 with double-sided tape. A sheet obtained by coating a polyethylene terephthalate (PET) sheet with a thickness of 0.5 mm with silicone rubber (trade name: KE12, manufactured by Shin-Etsu Chemical Co., Ltd.) with a thickness of 0.3 mm was used as the elastic layer of the transfer body 101. Furthermore, a condensate obtained by mixing glycidoxypropyltriethoxysilane and methyltriethoxysilane at a molar ratio of 1:1 and heating under reflux, and a photocationic polymerization initiator (trade name: SP150, manufactured by ADEKA) ) was prepared. Atmospheric pressure plasma treatment was performed so that the contact angle of water on the surface of the elastic layer was 10 degrees or less. Thereafter, the mixture was applied onto the elastic layer, and a film was formed by UV irradiation (high-pressure mercury lamp, cumulative exposure amount: 5000 mJ/cm ² ) and thermosetting (150°C, 2 hours) to form a film on the elastic layer. A transfer body 101 on which a surface layer with a thickness of 0.5 μm was formed was produced. Furthermore, by performing transfer printing of the same pattern 100,000 times using a transfer type inkjet recording device, a transfer body 101 was produced in which unevenness on the order of microns partially deteriorated within the surface of the transfer body. The surface roughness of the area where unevenness deterioration had progressed was 2.0 μm, and the surface roughness of the area where no deterioration had progressed was 0.5 μm.
The surface roughness of the transfer body was measured using a 10x lens of a laser microscope (product name: VK-9710, manufactured by KEYENCE) at an angle of view of 1350 μm x 1012 μm. Sa: Sa) was measured.

<Wax>
The following waxes were used.
W1: Fischer-Tropsch wax (synthetic wax, melting point: 83°C)
W2: Microcrystalline wax (petroleum wax melting point: 53℃)
W3: Low density PE (polyethylene) wax (synthetic wax melting point: 96°C)
W2 and W3 were mixed at a ratio of 1:1 (mass ratio).

<Preparation of reaction solution>
The reaction liquid applied by the reaction liquid applying device 103 had the following composition, and the applied amount was 1 g/m ² .
Glutaric acid 21.0%
Glycerin 5.0%
Surfactant (Megafac (registered trademark) F444, manufactured by DIC) 5.0%
Ion exchange water remainder

<Preparation of ink>
(Preparation of pigment dispersion)
10 parts of carbon black (trade name: Monak (registered trademark) 1100, manufactured by Cabot), aqueous resin solution (styrene-ethyl acrylate-acrylic acid copolymer, acid value: 150, weight average molecular weight (Mw): 8,000 , an aqueous solution with a resin content of 20.0%, neutralized with an aqueous potassium hydroxide solution), and 75 parts of pure water were mixed and charged into a batch type vertical sand mill (manufactured by Imex) to a diameter of 0.3 mm. 200 parts of zirconia beads were filled, and dispersion treatment was performed for 5 hours while cooling with water. After centrifuging this dispersion to remove coarse particles, a black pigment dispersion with a pigment content of 20.0% was obtained.

(Preparation of resin particle dispersion)
20 parts of ethyl methacrylate, 2.5 parts of 2,2'-azobis(2-methylbutyronitrile), and 2 parts of n-hexadecane were mixed and stirred for 0.5 hour. This mixture was added dropwise to 75 parts of an 8% aqueous solution of styrene-butyl acrylate-acrylic acid copolymer (acid value: 130 mgKOH/g, weight average molecular weight (Mw): 7,000) and stirred for 0.5 hours. did. Next, ultrasonic waves were irradiated for 3 hours using an ultrasonic irradiator. Subsequently, a polymerization reaction was carried out at 80° C. for 4 hours in a nitrogen atmosphere, and after cooling to room temperature, the mixture was filtered to prepare a resin particle dispersion having a resin particle content of 25.0%. Note that the resin content of the resin particle dispersion can be adjusted by diluting or concentrating the resin particle dispersion as necessary. The softening point of this resin is 105°C. Note that this softening point was measured according to JIS K 6828-2 "How to determine the minimum film forming temperature". That is, the resin dispersion was heated under an appropriate temperature gradient, and the boundary temperature between the transparent part where the film was formed and the part where the film was not formed was measured.

The resin particle dispersion and pigment dispersion obtained above were mixed with the following components. Note that the remainder of the ion-exchanged water is an amount that makes the total of all components constituting the ink 100.0%. The solid content rate in the ink is 10.0%.
Pigment 4.0%
Resin particles 6.0%
Glycerin 7.0%
Polyethylene glycol (number average molecular weight (Mn): 1,000) 1.0%
Surfactant (acetylenol (registered trademark) E100, manufactured by Kawaken Fine Chemicals)
0.5%
Ion-exchanged water (remainder) After sufficiently stirring and dispersing this, pressure filtration was performed using a microfilter (manufactured by Fuji Film Corporation) with a pore size of 3.0 μm to prepare a black ink.

<Printing using a transfer type inkjet recording device>
The wax was formed on the transfer body 101 using a wax forming device 110 to have a thickness of 1 μm.
Next, 0.7 g/m ² of the reaction liquid was applied by the reaction liquid applying device 103.
On top of the reaction liquid formed, the ink prepared above was applied from the ink applying device 104 to form an ink image. As the ejection pattern for the intermediate image, a solid image with a recording duty of 100% was formed in an area of 5 cm x 5 cm. Note that in the recording apparatus used in this example, the conditions were such that one ink droplet of 3.0 ng was applied to a unit area of 1/1,200 inches x 1/1,200 inches at a resolution of 1,200 dpi x 1,200 dpi. is defined as a recording duty of 100%.
Next, the liquid was removed from the ink image on the transfer body 101 by infrared heating by the liquid removing device 105, and the intermediate image after the liquid was removed was heated to a predetermined temperature. Next, as the transfer body 101 rotates in the direction of the arrow, the intermediate image is brought into contact with the recording medium 108 between the transfer body 101 and the pressing member 106, and the intermediate image is transferred from the transfer body 101 to the recording medium 108. .
The nip pressure between the transfer body 101 and the pressing member 106 was adjusted to 49 N/cm ² (5 kgf/cm ² ). In addition, the temperature during transfer was 105°C.

Next, a portion of the wax was deformed by heating with the heating device 111. As the heating and pressing means, hot air was used as a non-contact type, and a heating and pressing roller was used as a contact type. The nip pressure between the heated pressure roller 111b and the opposing roller 111c was adjusted to 68 N/cm ² (7 kgf/cm ² ). Table 1 shows the heating processing temperature Th at this time.
As the recording medium 108, OK Prince high-quality paper (trade name, manufactured by Oji Paper Co., Ltd., abbreviated as "P1") and Aurora coated paper (trade name, manufactured by Nippon Paper Industries, abbreviated as "P2") were used. The OK Prince high-quality paper P1 has fibers exposed on the surface, and the surface has large irregularities of several tens of μm. The surface of the aurora coated paper P2 is covered with a coating layer, and the surface is smooth and glossy.
Table 1 shows Examples 1 to 18 and Comparative Examples 1 to 5 by combining the above.

Next, under the materials and heating processing conditions shown in Table 1, transfer properties and images after heating by the heating device 111 were evaluated. The evaluation method and criteria are shown below. The results of image evaluation are shown in Table 2. Regarding the evaluation results, AA, A, and B are acceptable results.

<Evaluation 1: Evaluation of transferability>
It was visually evaluated whether there was any ink remaining on the transfer body after the transfer.
Evaluation Criteria A: There was no ink residue on the transfer body after transfer.
C: There was ink residue on the transfer body after transfer.

<Evaluation 2: Evaluation of the influence of gloss reduction due to micron-order unevenness on wax>
In the image heated by the heating device 111, a reduction in gloss due to micron-order unevenness on the wax was visually evaluated.
Evaluation Criteria A: No reduction in gloss due to unevenness on the image surface was observed.
C: Deterioration in gloss caused by unevenness on the image surface was visually recognized.
D: The transfer was so bad that it could not be evaluated.

<Evaluation 3: Evaluation of the effect of exposing blank areas due to ink movement>
In the image after heating by the heating device 111, it was evaluated by observation with an optical microscope (magnification: 20 times) whether there were any areas where the white paper portion of the base was exposed due to movement of the ink. Ink density and image quality were also visually evaluated.
Evaluation Criteria A: Under microscope observation, there were no areas where the underlying white paper was visible.
Visually, the density appeared high and the image quality was high.
B: Under microscope observation, there were some areas where the underlying blank paper was visible. Visually, the density appeared to be a little low, but the image quality was acceptable.
C: There were some areas where the underlying blank paper was visible, and there was a problem with the image quality.
D: The transfer was so bad that it could not be evaluated.

<Evaluation 4: Evaluation of the effect of ink exposure due to wax movement>
In the image after heating by the heating device 111, whether there were any areas where the ink was exposed due to movement of the wax was evaluated by microscopic observation in the same manner as described above. In addition, the image quality was evaluated visually.
Evaluation Criteria A: Microscopic observation revealed that there were no exposed areas of ink.
Visually, it had a natural texture and high image quality.
B: Microscopic observation revealed that there were some areas where the ink was exposed. Visually, there was a slight change in texture, but the image quality was acceptable.
C: Exposure of the ink could be visually confirmed, and the image quality was problematic.
D: Transfer is so bad that it cannot be evaluated.

<Evaluation 5: Evaluation of texture of printed matter>
The texture of the image after heating by the heating device 111 was visually evaluated.
Evaluation Criteria AA: High gloss.
A: The texture of the paper and the texture of the image were similar and natural.
C: Unevenness in gloss reduction reflecting deterioration of the transfer body was visible and unnatural.
D: The transfer was so bad that it could not be evaluated.

In Examples 1 to 6, since Th was higher than Tmr, all evaluation results were B or higher, which was good.
In Examples 7 to 12, since Th was higher than Tmr1, all evaluation results were B or higher, which was good.
In Examples 13 to 18, Th is not only higher than Tmr1 but also lower than Tmr2. Furthermore, TSi has a higher temperature than Th. Therefore, all evaluation results were A or higher.
Furthermore, in Examples 3, 6, 9, 12, 15, and 18 in which the heat processing was performed under pressure, the texture of the image with a rating of 5 was particularly excellent with high gloss.
In Comparative Example 1, no wax was applied on the transfer body. Therefore, all evaluation results including transferability were C or lower.
In Comparative Example 2, Th is lower than Tmr. Therefore, the wax did not melt, and the micron-order unevenness on the wax layer of the transferred image could not be smoothed, and the results of evaluations 2 and 5 were C.
Comparative Examples 3 to 5 also have Th lower than Tmr1. Therefore, regardless of the type of recording medium and the heat processing method, the wax does not melt as in Comparative Example 2, and the micron-order unevenness on the wax layer of the transferred image cannot be smoothed, resulting in a rating of 2. The result of 5 was C.

The present invention includes the following method.
[Method 1]
The following steps (i) to (iii):
(i) Wax application step of applying wax onto the transfer body;
(ii) a reaction liquid applying step of applying a reaction liquid that reacts with the ink and thickens the ink onto the transfer body;
(iii) an ink application step of applying an ink containing a coloring material onto the transfer body; an intermediate image forming step (A) of forming an intermediate image containing wax on the transfer body; and an intermediate image forming step (A) of forming an intermediate image containing wax on the transfer body. a transfer step (B) of bringing the intermediate image formed in contact with a recording medium and transferring it to the recording medium to form a transferred image including a wax layer on the surface;
a heating step (C) of heating the transferred image on the recording medium to deform at least a portion of the wax layer;
The wax has at least one melting point Tmr, and the temperature Th of the surface of the wax layer in the heating step (C) and the melting point Tmr have a relationship expressed by Formula 1-1,
Heating in the heating step (C) is performed without contacting or applying pressure to the transferred image,
The pressure P1 when transferring the intermediate image to the recording medium in the transfer step (B) and the pressure P2 when heating the transferred image while applying pressure in the heating step (C) are expressed by equation 1-2. An inkjet recording method characterized by having the relationship expressed;
Tmr≦Th (Formula 1-1)
P1<P2 (Formula 1-2).
[Method 2]
The inkjet recording method according to [Method 1], wherein the ink contains a resin, and the glass transition point or softening point Tsi of the resin has a relationship expressed by Formula 2;
Tmr≦Th<Tsi (Formula 2).
[Method 3]
The wax is a mixture of multiple materials with different melting points,
The inkjet recording method according to [Method 1] or [Method 2], which has the relationship expressed by the following formula 3 with the temperature Th, when the lowest melting point Tmr1 among the melting points of the plurality of materials of the wax:
Tmr1≦Th (Formula 3).
[Method 4]
The inkjet recording method according to [Method 3], wherein the highest melting point Tmr2 among the melting points of the plurality of wax materials satisfies formula 5;
Th<Tmr2 (Equation 5).
[Method 5]
The heating in the heating step (C) is either non-contact heating from the surface of the wax layer or applying heat and pressure to the wax layer from the surface of the wax layer [Method] 1] to [Method 4].

Further, the present invention includes the following configuration.
[Configuration 1]
A transfer-type inkjet recording device that forms an intermediate image on a transfer body and transfers the intermediate image onto a recording medium,
a wax application device that applies wax onto the transfer body;
a reaction liquid applying device that applies a reaction liquid that reacts with the ink and thickens the ink onto the transfer body;
an ink applying device that applies the ink containing a coloring material onto the transfer body using an inkjet method to form an ink image;
a liquid removal device that removes liquid from the ink image and forms an intermediate image on the transfer body;
a transfer device that brings the intermediate image into contact with the recording medium and transfers the transfer image with a wax layer formed on the surface;
a heating device that heats the wax layer of the transferred image;
Equipped with
The wax has at least one melting point Tmr, the heating device is a device that heats the surface of the wax layer at a temperature Th, and the Th and the melting point Tmr have a relationship expressed by Formula 1-1. has
The transfer device is a device that applies pressure P1 when transferring the intermediate image to a recording medium, and the heating device heats the transferred image without contact or while applying pressure P2. An inkjet recording device, characterized in that the P1 and the P2 have a relationship expressed by Formula 1-2;
Tmr≦Th (Formula 1-1)
P1<P2 (Formula 1-2).

21 Wax layer 22 Ink layer 23 Recording medium 24 Convex portion 25 Concave portion 100 Transfer type inkjet recording device 101 Transfer body 102 Support member 103 Reaction liquid applying device 104 Ink applying device 105 Liquid removing device 106 Pressing member 107 Recording medium transport device 108 Recording medium 109 Transfer body cleaning member 110 Wax applying device 111 Heating device 111a Non-contact heating device 111b, 111c Roller 111d, 111e Belt 114 Thermometer

Claims (9)

The following steps (i) to (iii):
(i) Wax application step of applying wax onto the transfer body;
(ii) a reaction liquid applying step of applying a reaction liquid that reacts with the ink and thickens the ink onto the transfer body;
(iii) an ink application step of applying ink containing a coloring material onto the transfer body; an intermediate image forming step (A) of forming an intermediate image containing wax on the transfer body;
a transfer step (B) of bringing the intermediate image formed on the transfer body into contact with a recording medium and transferring it to the recording medium to form a transfer image including a wax layer on the surface;
a heating step (C) of heating the transferred image on the recording medium to deform at least a portion of the wax layer;
The wax has at least one melting point Tmr, and the temperature Th of the surface of the wax layer in the heating step (C) and the melting point Tmr have a relationship expressed by Formula 1-1,
Heating in the heating step (C) is performed without contacting or applying pressure to the transferred image,
The pressure P1 when transferring the intermediate image to the recording medium in the transfer step (B) and the pressure P2 when heating the transferred image while applying pressure in the heating step (C) are expressed by formula 1-2. An inkjet recording method characterized by having the relationship expressed;
Tmr≦Th (Formula 1-1)
P1<P2 (Formula 1-2). The inkjet recording method according to claim 1, wherein the ink contains a resin, and the glass transition point or softening point Tsi of the resin has a relationship expressed by Formula 2;
Tmr≦Th<Tsi (Formula 2). The wax is a mixture of multiple materials with different melting points,
The inkjet recording method according to claim 1, which has a relationship with the temperature Th expressed by the following formula 3, when the lowest melting point Tmr1 among the melting points of the plurality of materials of the wax:
Tmr1≦Th (Formula 3). The wax is a mixture of multiple materials with different melting points,
The inkjet recording method according to claim 2, wherein the inkjet recording method has a relationship expressed by the following formula 4 with the temperature Th when the lowest melting point Tmr1 among the melting points of the plurality of materials of the wax:
Tmr1≦Th<Tsi (Formula 4). The inkjet recording method according to claim 3, wherein the highest melting point Tmr2 among the melting points of the plurality of wax materials satisfies formula 5;
Th<Tmr2 (Equation 5). The inkjet recording method according to claim 4, wherein the highest melting point Tmr2 of the melting points of the plurality of wax materials satisfies formula 5;
Th<Tmr2 (Equation 5). The inkjet recording method according to claim 6, wherein the glass transition point or softening point Tsi, the temperature Th, and the melting point Tmr2 of the resin satisfy the following equation 6;
Th<Tmr2≦Tsi (Formula 6). A claim in which the heating in the heating step (C) is either non-contact heating from the surface of the wax layer or applying heat and pressure to the wax layer from the surface of the wax layer. 8. The inkjet recording method according to any one of 1 to 7. A transfer-type inkjet recording device that forms an intermediate image on a transfer body and transfers the intermediate image onto a recording medium,
a wax application device that applies wax onto the transfer body;
a reaction liquid applying device that applies a reaction liquid that reacts with the ink and thickens the ink onto the transfer body;
an ink applying device that applies the ink containing a coloring material onto the transfer body using an inkjet method to form an intermediate image on the transfer body;
a transfer device that brings the intermediate image into contact with the recording medium and transfers the transfer image with a wax layer formed on the surface;
a heating device that heats the wax layer of the transferred image,
The wax has at least one melting point Tmr, the heating device is a device that heats the surface of the wax layer at a temperature Th, and the Th and the melting point Tmr have a relationship expressed by Formula 1-1. has
The transfer device is a device that applies pressure P1 when transferring the intermediate image to a recording medium, and the heating device heats the transferred image without contact or while applying pressure P2. An inkjet recording device, characterized in that the P1 and the P2 have a relationship expressed by Formula 1-2;
Tmr≦Th (Formula 1-1)
P1<P2 (Formula 1-2).

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