JP2015024504A - Image recording method - Google Patents

Abstract

High-quality image recording is performed on an intermediate transfer member by reducing landing deviation of ink droplets and deformation of ink dot shape. An image recording method capable of recording a high-quality image on a recording medium is provided. An image recording method comprising a reaction liquid application step, an intermediate image formation step, and a transfer step. The intermediate transfer member has a first surface and a second surface opposite to the first surface opposite to the first surface, and the intermediate transfer member transfers the intermediate transfer from the first surface to the second surface. Has pores that penetrate the body. In the reaction liquid application step, the reaction liquid is applied to the second surface, and the reaction liquid is moved from the second surface to the first surface through the pores. In the intermediate image forming step, ink is applied on the first surface of the intermediate transfer member. [Selection] Figure 1

Description

  The present invention relates to an image recording method.

  As an application example of inkjet recording technology, an intermediate image is formed on an intermediate transfer member, and the intermediate image formed on the intermediate transfer member is transferred to a desired recording medium, thereby recording the intermediate image on the recording medium. There is a method to do. In this method, the ink ejected from the ink jet head is once adhered to the intermediate transfer member, and an intermediate image in which the fluidity of the ink is reduced to some extent is formed on the intermediate transfer member. Thereafter, the intermediate image is transferred from the intermediate transfer member to the recording medium.

  In the method using the intermediate transfer member, an intermediate image is once formed on the intermediate transfer member. For this reason, an image can be recorded without being affected by a recording medium such as paper. In this case, a non-absorbing surface is used for the surface of the intermediate transfer member in terms of transferability and cleaning properties. However, when ink that is liquid is applied to the non-absorbing surface, the ink flows or is repelled. Therefore, in the above case, it is very difficult to record a high-quality image.

  Therefore, Patent Document 1 proposes a method of controlling the fluidity of ink by applying a liquid that reacts with ink onto an intermediate transfer member and bringing the ink into contact with the liquid to react these two liquids. Yes. By using this method, it is possible to prevent “beading” in which adjacent dots attract each other on the surface of the intermediate transfer member. In addition, it is possible to prevent “bleeding” in which the ink in the printing portion bleeds into the non-printing portion like a mist at the boundary between the printing region and the non-printing region. As a result, it is possible to record a good image.

JP 2002-321350 A

  However, in the method of Patent Document 1, ink droplets are applied to the intermediate transfer member via the reaction liquid layer. For this reason, the finally obtained image quality greatly depends on the application state of the reaction solution. That is, when the reaction liquid is not properly applied onto the intermediate transfer member, for example, when it is not formed with a uniform thickness, landing deviation of the ink droplets or deformation of the dot shape occurs. As a result, high-quality image recording on the intermediate transfer member, and consequently high-quality image recording on the recording medium may be hindered.

  Accordingly, an object of the present invention is to reduce the landing deviation of ink droplets and the deformation of the ink dot shape by supplying a reaction liquid on the intermediate transfer member so as to have an appropriate distribution in the image recording method of the intermediate transfer method. There is. Furthermore, high quality image recording on the intermediate transfer member enables high quality image recording on the recording medium.

One embodiment is:
A reaction solution applying step for applying a reaction solution to the intermediate transfer member, an intermediate image forming step for forming an intermediate image by applying ink to the intermediate transfer member to which the reaction solution is applied, and transferring the intermediate image to a recording medium. An image recording method comprising:
The intermediate transfer member has a first surface and a second surface opposite to the first surface opposite to the first surface;
The intermediate transfer member has pores penetrating the intermediate transfer member from the first surface to the second surface;
In the reaction liquid application step, the reaction liquid is applied to the second surface, the reaction liquid is moved from the second surface to the first surface through the pores,
In the intermediate image forming step, an ink is applied to a first surface of the intermediate transfer member.

  By reducing the landing deviation of ink droplets and the deformation of the ink dot shape, high-quality image recording can be performed on the intermediate transfer member. As a result, an image recording method capable of recording a high-quality image on a recording medium can be provided.

It is a schematic diagram which shows schematic structure of an image recording device. It is a figure explaining the prior art example in which the reaction liquid is not appropriately given to an intermediate transfer body. It is a figure which shows the state of the reaction liquid on the intermediate transfer body in one Embodiment of this invention. It is a figure explaining the relationship between the pore distribution of the intermediate transfer body and the ink dots in another embodiment of the present invention. FIG. 10 is a diagram for explaining the relationship between the pore distribution of an intermediate transfer member and ink dots in another embodiment of the present invention.

  In the image recording method of an example of the present invention, an intermediate transfer member having pores is used. The intermediate transfer member has a first surface and a second surface opposite to the first surface so as to face the first surface, and the pores are intermediate from the first surface to the second surface. The transfer body is penetrated in the thickness direction. The “first surface” represents the outer surface on which ink is applied and the intermediate image is formed thereon, and the “second surface” represents the outer surface on the back side of the first surface. In addition, each pore may penetrate from the first surface to the second surface independently, or a plurality of pores may be connected inside the intermediate transfer member.

  First, in the reaction liquid application step, the reaction liquid is applied to the back surface (second surface) side of the intermediate transfer member. The reaction solution applied to the second surface moves from the second surface to the first surface through the pores by capillary action or the like.

  Next, in the intermediate image forming step, ink is applied onto the first surface of the intermediate transfer body to which the reaction liquid has been applied, whereby the reaction liquid and the ink are reacted to form an intermediate image composed of these. At this time, it is possible to reduce the landing deviation of the ink droplets and the deformation of the ink dot shape, and to record a high-quality intermediate image on the intermediate transfer member. As a result, it is possible to provide an image recording method capable of recording a high-quality image on a recording medium when the intermediate image is transferred to the recording medium in a later transfer step. The reason why such an excellent effect is obtained is not clear, but the present inventors presume as follows.

  In general, in image recording of an intermediate transfer method in which ink is applied onto an intermediate transfer body to which a reaction liquid has been applied, the image quality greatly depends on the application state of the reaction liquid. What is important here is the film thickness and uniformity of the reaction solution on the intermediate transfer member. FIG. 2A shows a state where the film thickness of the reaction solution is excessive as a conventional example in which the reaction solution is not appropriately applied. In the case of FIG. 2A, the ink droplet 22 that has contacted the reaction liquid 23 on the intermediate transfer body 21 reacts with the reaction liquid instantaneously, and its fluidity decreases. However, in the case of FIG. 2A, since the reaction solution 23 is thick, the reaction between the intermediate image formed by the reaction between the ink droplet 22 and the reaction solution 23 and the intermediate transfer member 21 has fluidity. A layer of liquid 23 remains. In such a state, the intermediate image is likely to move due to impact when an ink droplet applied later lands, the movement of the intermediate transfer body 21, or the cohesive force of the reaction liquid, and the positional deviation of the dots occurs. There is.

  FIG. 2B shows a state in which the film thickness of the reaction solution 23 is non-uniform as another example in which the reaction solution is not properly applied. In general, the shape of the ink droplet 22 that has landed on the reaction liquid 23 is affected by the resistance at the time of landing, the surface tension of the ink and the reaction liquid, the strength of the cohesive force between the ink droplet 22 and the reaction liquid 23, and the like. For example, the intensity of cohesive force will be described as an example. As shown in FIG. 2B, when the film thickness of the reaction solution 23 is not uniform, the reaction occurs in the portion where the reaction solution 23 is thick. Therefore, the fluidity of the ink is instantly deprived and the ink droplet 22 does not spread. On the other hand, in the portion where the film thickness of the reaction liquid 23 is thin, the reaction is weak and the ink droplet 22 tends to spread. Thus, if the reaction liquid film thickness is not uniform, the dot diameters of the ink droplets 22 may become uneven. Alternatively, the shape of the ink droplet may be deformed due to an uneven landing resistance of the ink droplet or the like.

  Therefore, in an example of the present invention, a porous body having pores is used as the intermediate transfer body, and the reaction liquid is applied from the back surface (second surface) side of the intermediate transfer body. The reaction solution applied in this way passes through the pores and moves to the front surface (first surface) side of the intermediate transfer member, and the reaction solution has a uniform and preferable distribution on the first surface. Form a layer. Thus, a high-quality intermediate image can be formed on the intermediate transfer member by a reaction with the ink applied on the reaction liquid layer on the first surface. As described above, the mechanism by which the reaction solution is supplied in a uniform and appropriate distribution on the first surface of the intermediate transfer member is not clear, but the present inventors speculate as follows. .

  The reaction liquid supplied from the back surface (second surface) side of the intermediate transfer member rises from the second surface of the intermediate transfer member to the vicinity of the first surface by capillary action. And the reaction liquid which rose to the vicinity of the first surface forms a meniscus, and the state is maintained. In this state, an external force is applied to the reaction solution from the back side by a pressurizing method or vibration, whereby the meniscus is destroyed and the reaction solution can be pushed out onto the first surface of the intermediate transfer member.

  At this time, due to the relationship between the surface tension of the reaction solution and the surface energy of the first surface of the intermediate transfer member, a combination of the intermediate transfer member and the reaction solution that prevents the reaction solution from getting wet and spreading on the first surface of the intermediate transfer member. Is preferably selected. Thereby, as shown in FIG. 3, the reaction liquid 32 can be maintained on the first surface of the intermediate transfer member 31 in a raised state. Examples of the combination in which the reaction liquid 32 does not wet and spread on the first surface of the intermediate transfer member include those having a large difference in surface tension such as water and silicone rubber.

  In this example, since the reaction solution does not wet and spread on the first surface of the intermediate transfer member, the reaction solution that has passed through different pores is dispersed without mixing on the first surface of the intermediate transfer member. Exists in a state. Thus, by applying the reaction liquid in a convex shape onto the first surface of the intermediate transfer member in a dispersed state, the amount of the reaction liquid to be applied can be precisely adjusted. Therefore, the reaction solution can be supplied uniformly and densely on the first surface of the intermediate transfer member. As a result, landing deviation of ink droplets and deformation of the ink dot shape can be effectively reduced, and a high-quality intermediate image can be recorded on the intermediate transfer member. Finally, it is possible to provide an image recording method capable of recording a high-quality image on a recording medium.

  When a hydrophilic reaction liquid is used, it is preferable to use a water-repellent material or perform a water-repellent treatment on the surface of the intermediate transfer member. As a result, the reaction liquid 32 raised in a convex shape can be formed on the first surface of the intermediate transfer member 31 more easily. As a result, the control of the amount of the reaction solution applied onto the intermediate transfer member becomes more appropriate, and it becomes possible to form a higher-quality intermediate image on the intermediate transfer member.

  Further, as shown in FIG. 4A, it is preferable that the maximum value of the pore diameter r of the pores 41 on the first surface of the intermediate transfer member is equal to or smaller than the diameter of the ink dots forming the intermediate image. As a result, the ink dots that have landed on the reaction liquid do not move on the reaction liquid or enter the pores of the intermediate transfer body, so that a high-quality intermediate image is formed on the first surface of the intermediate transfer body. It becomes possible to record.

  Furthermore, it is preferable to distribute the pores so that the diameter R of the largest circumscribed circle in contact with each pore is equal to or less than the diameter of the ink dots forming the intermediate image. As a result, the ink can surely come into contact with the reaction liquid, and a higher-quality intermediate image can be formed on the intermediate transfer member. The reason for this will be described with reference to FIG. Of the circumscribed circles 42 to 45 shown in FIG. 4B, the diameter of the circumscribed circle 42 having the largest diameter is R. When an ink dot having a diameter R ′ is driven onto the intermediate transfer member, if R <R ′, the ink dot overlaps with the pore regardless of the position on the intermediate transfer member, that is, contacts with the reaction liquid. Will be able to.

In particular, the pores of the intermediate transfer member are distributed so as to have a substantially hexagonal close-packed arrangement on the first surface of the intermediate transfer member,
a <√3 (R + r) / 2
It is preferable to satisfy. In the above formula, a represents the pitch between the pores on the first surface, r represents the pore diameter, and R represents the diameter of the ink dot for forming the intermediate image. Accordingly, the ink always comes into contact with the reaction liquid, and the reaction liquid can be more uniformly and densely distributed, so that a higher-quality intermediate image can be formed on the intermediate transfer member. The reason for this will be described with reference to FIG. First, FIG. 5A shows a state where the three pores 51 adjacent to the ink dots just touch each other. At this time, the ink dot 52 is a circumscribed circle of the three adjacent pores 51. Accordingly, the condition at this time is when the diameter of the ink dots 52 is R, the pitch of the pores 52 is a, and the pore diameter is r, and a = √3 (R + r) / 2 is satisfied. Therefore, if the pitch a between the pores is larger than √3 (R + r) / 2, the ink dots 52 and the pores 51 do not contact each other as shown in FIG. It is not preferable. On the other hand, if the pitch a between the pores is smaller than √3 (R + r) / 2, the ink dots 52 and the pores 51 always come into contact as shown in FIG. That is, when a <√3 (R + r) / 2 is satisfied, the ink and the reaction liquid always come into contact.

  The pore diameter r, the maximum value of the pore diameter r, the diameter R of the ink dots, and the pitch a between the pores can be measured by the methods described in the examples described later. Further, the diameter of the largest circumscribed circle in contact with each pore can also be measured by the method described in the examples as described above.

  Further, there is no particular limitation on the method of forming the pores of the intermediate transfer member so that the pores of the intermediate transfer member are arranged in a substantially hexagonal close-packed arrangement when the intermediate transfer member is viewed from the surface (first surface). For example, when the material of the intermediate transfer member is aluminum and the pores of the intermediate transfer member are created by anodizing the aluminum, the pores can be easily formed in a hexagonal close-packed arrangement.

  Below, each process which comprises the image recording method of this embodiment, and each material used for an image recording method are demonstrated, but this invention is not limited to these.

<Intermediate transfer member>
The intermediate transfer member is a base material that holds ink and forms an intermediate image. Examples of the shape of the intermediate transfer member include a sheet shape, a roller shape, a drum shape, a belt shape, and an endless web shape. Further, the size of the intermediate transfer member can be freely selected according to the target print image size. As a material constituting the intermediate transfer member, various materials such as resin, ceramic, metal, and elastomer can be appropriately used. Among the above materials, aluminum is preferable because regular and uniform pores can be easily formed by applying an anodizing treatment. In addition, a water-repellent material having a fluorine compound and a water-repellent material having a siloxane skeleton are preferable because of low surface energy and excellent releasability of intermediate images.

  The intermediate transfer member can be subjected to an appropriate surface treatment. Examples of surface treatments include water repellent treatment, flame treatment, corona treatment, plasma treatment, polishing treatment, roughening treatment, active energy ray (UV / IR / RF) irradiation treatment, ozone treatment, surfactant treatment, silane A coupling process is mentioned. It is also preferable to perform a combination of a plurality of these processes. Preferably, a water repellent treatment is performed.

<Porous shape>
The pore diameter and pitch of the intermediate transfer member can be appropriately set according to the characteristics of ink, reaction liquid, intermediate transfer member, process conditions, and the like. The area ratio of the pores to the first surface of the intermediate transfer member is preferably 5% or more and 70% or less. If the area ratio of the pores exceeds 70%, the mechanical strength of the intermediate transfer member may be insufficient. On the other hand, when the area ratio of the pores is less than 5%, it is difficult to realize an appropriate distribution of the reaction solution on the first surface and to provide the necessary amount of the reaction solution. Preferably, the area ratio of the pores is 10% or more and 55% or less.

  The pore diameter of the intermediate transfer member is preferably smaller than the ink dot diameter. When the pore diameter of the intermediate transfer member is larger than the ink dot diameter, the reaction liquid continuously exists in a range wider than the ink dot size in the pore, and the ink droplets landed in this move on the reaction liquid. The image may be distorted. Further, it is not preferable because ink droplets may enter the pores. In general, since the ink dot diameter in inkjet is about 30 μm, the pore diameter of the intermediate transfer member is preferably 30 μm or less, more preferably 10 μm or less, and further preferably 3 μm or less. The pore diameter of the intermediate transfer member is preferably 0.01 μm or more. If the pore diameter is less than 0.01 μm, the reaction solution will not easily penetrate into the pores due to capillary action, and it will be difficult to apply the necessary amount of the reaction solution on the first surface.

  The pitch between the pores is preferably 0.05 μm or more and 30 μm or less. If it is smaller than 0.05 μm, there may be a problem in durability of the intermediate transfer member, which is not preferable. On the other hand, when the thickness is larger than 30 μm, the probability that the ink and the reaction liquid do not contact with each other increases, which is not preferable.

<Method for forming pores>
The method for forming the pores in the intermediate transfer member is not particularly limited. For example, electron beam lithography, anodizing treatment, foaming method, stretching method, dry etching method, sintering method, molten layer separation method, phase change method And an extraction method. Among these, aluminum anodizing treatment is particularly preferable because pores having a fine and uniform pattern can be easily formed.

<Reaction solution>
The reaction liquid contains an ink thickening component. Here, “increased ink viscosity” means that a coloring material or resin that is a composition constituting the ink chemically reacts or physically adsorbs by contact with the ink thickening component, This represents a case where an increase in viscosity of the entire ink is recognized. Further, “increasing the viscosity of the ink” includes a case where the viscosity is locally increased by agglomeration of a part of the ink composition such as a coloring material. The ink thickening component has the effect of reducing bleeding and beading during intermediate image formation by reducing the fluidity of a part of the ink and / or ink composition on the intermediate transfer member. As the ink thickening component, conventionally known materials such as polyvalent metal ions, organic acids, cationic polymers, and porous fine particles can be used without particular limitation. Of these, polyvalent metal ions and organic acids are particularly preferred. The reaction liquid also preferably contains a plurality of types of ink thickening components. The content of the ink thickening component in the reaction liquid is preferably 5% by mass or more based on the total mass of the reaction liquid.

Specific examples of metal ions that can be used as the ink viscosity increasing component include divalent metals such as Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Sr ²⁺ , Ba ^2+, and Zn ^{2+. Examples} thereof include metal ions and trivalent metal ions such as Fe ³⁺ , Cr ³⁺ , Y ^3+, and Al ³⁺ .

  Specific examples of organic acids that can be used as the ink thickening component include oxalic acid, polyacrylic acid, formic acid, acetic acid, propionic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, and levulin. Acid, succinic acid, glutaric acid, glutamic acid, fumaric acid, citric acid, tartaric acid, lactic acid, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, Examples thereof include oxysuccinic acid and dioxysuccinic acid.

  The reaction solution may contain an appropriate amount of water or an organic solvent. The water used in this case is preferably water deionized by ion exchange or the like. Moreover, it does not specifically limit as an organic solvent used for a reaction liquid, Any well-known organic solvent can be used.

  Various resins can also be added to the reaction solution. When an appropriate resin is added, it becomes possible to improve the adhesion to the recording medium during transfer and to increase the mechanical strength of the final image. Therefore, it is preferable to add a resin to the reaction solution. The material that can be used as the resin is not particularly limited as long as it can coexist with the ink thickening component.

  Further, the reaction liquid can be used by appropriately adjusting the surface tension and viscosity by adding a surfactant or a viscosity modifier. In particular, when the surface of the intermediate transfer member has water repellency, the surface of the reaction solution to be applied onto the intermediate transfer member can be adjusted by adjusting the surface of the intermediate transfer member with a surfactant or a viscosity modifier so that the surface becomes hydrophilic. The amount can be controlled more precisely. For this reason, it is preferable to add a surfactant or a viscosity modifier to the reaction solution. The material to be used is not particularly limited as long as it can coexist with the ink thickening component, and specific examples thereof include acetylenol E100 (manufactured by Kawaken Fine Chemical Co., Ltd.) as a surfactant.

<Ink>
As the ink used in the present embodiment, a coloring material in which a known dye, carbon black, organic pigment or the like is dissolved and / or dispersed can be used. Among these, various pigments are suitable because they have characteristics of printed matter durability and quality.

  It does not specifically limit as a pigment, A well-known inorganic pigment and organic pigment can be used. Specifically, C.I. I. A pigment represented by a (color index) number can be used. Moreover, it is also preferable to use carbon black as a black pigment. The content of the pigment in the ink is preferably 0.5% by mass or more and 15.0% by mass or less, and more preferably 1.0% by mass or more and 10.0% by mass or less with respect to the total mass of the ink. .

  As the dispersant for dispersing the pigment, any of those used in conventionally known ink jet technology can be used. Among these, it is preferable to use a water-soluble dispersant having both a hydrophilic part and a hydrophobic part in its molecular structure. In particular, a pigment dispersant made of a resin obtained by copolymerizing at least a hydrophilic monomer and a hydrophobic monomer can be preferably used. Here, there is no restriction | limiting in particular about each monomer which can be used, A conventionally well-known thing can be used conveniently. Specific examples of the hydrophobic monomer include styrene, styrene derivatives, alkyl (meth) acrylate, and benzyl (meth) acrylate. Examples of the hydrophilic monomer include acrylic acid, methacrylic acid, maleic acid and the like.

  The acid value of the dispersant is preferably 50 mgKOH / g or more and 550 mgKOH / g or less. Moreover, it is preferable that the weight average molecular weights of a dispersing agent are 1000 or more and 50000 or less. The mass ratio of the pigment and the dispersant is preferably in the range of 1: 0.1 to 1: 3. It is also preferable to use a so-called self-dispersing pigment that does not use a dispersing agent and that can be dispersed by surface modification of the pigment itself.

  The ink can be used by containing various fine particles having no coloring material. Among these, resin fine particles are preferable because they may be effective in improving image quality and fixability. The material of the resin fine particles that can be used is not particularly limited, and a known resin can be appropriately used. Specifically, homopolymers such as polyolefin, polystyrene, polyurethane, polyester, polyether, polyurea, polyamide, polyvinyl alcohol, poly (meth) acrylic acid and salts thereof, poly (meth) acrylate alkyl, polydiene, or the like The copolymer which combined these two or more is mentioned. The weight average molecular weight of the resin is preferably in the range of 1,000 to 2,000,000. The amount of the resin fine particles in the ink is preferably 1% by mass or more and 50% by mass or less, more preferably 2% by mass or more and 40% by mass or less with respect to the total mass of the ink.

  Further, it is preferably used as a resin fine particle dispersion in which resin fine particles are dispersed in a liquid. The dispersion method is not particularly limited, but a so-called self-dispersing resin fine particle dispersion in which a monomer having a dissociable group is dispersed using a homopolymerized or a copolymerized resin is preferable. Here, examples of the dissociable group include a carboxyl group, a sulfonic acid group, and a phosphoric acid group, and examples of the monomer having the dissociable group include acrylic acid and methacrylic acid. A so-called emulsification-dispersed resin fine particle dispersion in which resin fine particles are dispersed with an emulsifier can also be suitably used. As the emulsifier here, a known surfactant is preferably used regardless of low molecular weight or high molecular weight. The surfactant is preferably nonionic or has the same charge as the resin fine particles. The resin fine particle dispersion preferably has a dispersed particle diameter of 10 nm to 1000 nm, and more preferably 100 nm to 500 nm.

  It is also preferable to add various additives for stabilization when preparing the resin fine particle dispersion. Examples of suitable additives include n-hexadecane, dodecyl methacrylate, stearyl methacrylate, chlorobenzene, dodecyl mercaptan, olive oil, blue dye (Blue 70), and polymethyl methacrylate.

  The ink may contain a surfactant. Specific examples of the surfactant include acetylenol EH (manufactured by Kawaken Fine Chemical Co., Ltd.). The amount of the surfactant in the ink is preferably 0.01% by mass or more and 5.0% by mass or less with respect to the total mass of the ink.

  The ink can contain water and / or a water-soluble organic solvent as a solvent. The water is preferably water deionized by ion exchange or the like. Further, the water content in the ink is preferably 30% by mass or more and 97% by mass or less with respect to the total mass of the ink. The kind of water-soluble organic solvent is not particularly limited, and any known organic solvent can be used. Specific examples include glycerin, diethylene glycol, and polyethylene glycol. The content of the water-soluble organic solvent in the ink is preferably 3% by mass or more and 70% by mass or less with respect to the total mass of the ink. In addition to the above components, the ink may be variously adjusted as necessary, such as a pH adjuster, a rust inhibitor, a preservative, an antifungal agent, an antioxidant, a reduction inhibitor, a water-soluble resin and its neutralizer, and a viscosity modifier. An additive may be contained. In addition to the water-soluble ink, oil-based ink can be used.

1. Image Recording Method The image recording method of the present embodiment includes a reaction liquid application step for applying a reaction liquid to an intermediate transfer body, and intermediate image formation for forming an intermediate image by applying ink to the intermediate transfer body to which the reaction liquid has been applied. And a transfer step of transferring the intermediate image to the recording medium. Below, each process is demonstrated in detail.

(1) Reaction liquid application step As a method for applying the reaction liquid, the reaction liquid is applied to the back surface (second surface) side of the intermediate transfer member, and the inside of the pores is moved from the second surface by capillary action, and finally the reaction liquid is applied. In addition, a method of distributing on the front surface (first surface) of the intermediate transfer member by a pressure method, vibration or the like is used. As a means for supplying the reaction liquid to the second surface side of the intermediate transfer member, a non-contact type such as a spray or a contact type such as a porous material such as a sponge can be used. For example, when a porous body is used, a non-woven fabric, a woven fabric, a mesh, a net, or the like formed from a polytetrafluoroethylene resin, a polyester resin, or the like, and a composite material of these can be used. The reaction liquid can be supplied by impregnating the porous body with the reaction liquid and bringing it into contact with the back surface of the intermediate transfer body.

(2) Intermediate image forming step Next, an ink for image formation is selectively applied onto the first surface of the intermediate transfer body to which the reaction liquid has been applied, using, for example, an ink jet device. Thereby, on the intermediate transfer member, the reaction liquid and ink applied in advance react to form an intermediate image. As the ink jet device, any of various ink jet devices proposed in the ink jet liquid ejection technique can be used. For example, the following forms can be mentioned.
A form in which ink is ejected by causing film boiling in the ink by an electro-thermal converter to form bubbles.
A mode in which ink is ejected by an electro-mechanical converter.
-A mode of discharging ink using static electricity.
Among these, particularly from the viewpoint of high-speed and high-density printing, those using an electro-thermal converter can be suitably used.

  Moreover, there is no restriction | limiting in particular as a form of the whole inkjet device. For example, a so-called shuttle-type inkjet discharge head that performs recording while scanning the head perpendicular to the traveling direction of the intermediate transfer member can be used. In addition, a so-called line head type ink jet type discharge head in which ink discharge ports are arranged in a line substantially perpendicular to the traveling direction of the intermediate transfer member (that is, substantially parallel to the axial direction in the case of a drum shape) is used. You can also.

(3) Transfer process In the transfer process, the intermediate image on the intermediate transfer member is pressed against the recording medium to transfer the intermediate image to the recording medium. At this time, it is preferable to apply pressure from both sides of the intermediate transfer member and the recording medium using a pressure roller because an intermediate image is efficiently transferred and formed.

(4) Other steps The following steps can be added to the above series of basic steps. First, it is preferable to add (3) a step of reducing the liquid component from the intermediate image prior to the transfer step. This is because if the liquid component is insufficiently reduced, excess liquid may overflow or overflow in a transfer process involving pressure bonding, resulting in a transfer failure such as disturbing the image. As a technique for reducing the liquid component, any of various conventionally used techniques can be suitably applied. For example, a method using heating, a method of blowing low-humidity air, a method of reducing pressure, a method of bringing an absorber into contact with each other, and a method of combining these are preferably used. It is also possible to carry out by natural drying.

  (3) As an additional step after the transfer step, the recording medium on which image recording by transfer has been performed may be pressurized with a fixing roller or the like to improve surface smoothness. At this time, it is possible to heat the fixing roller so that the image is immediately fastened.

Further, considering the continuous use of the intermediate transfer member from the viewpoint of productivity, it is preferable to add a step of cleaning and regenerating the surface of the intermediate transfer member in preparation for the next image formation after the transfer. . As a method for performing cleaning, it is desirable to use the following method.
A method of rinsing or wiping the intermediate transfer member while applying water in a shower-like manner to the first surface of the intermediate transfer member.
A direct cleaning method such as bringing the first surface of the intermediate transfer member into contact with the water surface.
A method of performing wiping such as bringing a wet Molton roller into contact with the first surface of the intermediate transfer member.
Of course, it is also effective to use these methods in combination.

  Hereinafter, the present invention will be described more specifically with reference to examples of image recording methods according to the present invention and comparative examples. Of course, the present invention is not limited to the following examples. In the text, “parts” and “%” are based on mass unless otherwise specified.

  FIG. 1 is a schematic diagram showing an image recording apparatus used in each embodiment. In the apparatus shown in FIG. 1, the intermediate transfer member 1 has a belt shape and is stretched around a conveyance drum 9. The intermediate transfer member 1 is conveyed in the direction of the arrow. In synchronization with this conveyance, the sponge roller 2, the ink jet device 3, the air blower 4, the heater 5, the pressure roller 7, and the cleaning unit 8 that are arranged in the periphery so as to face the intermediate transfer member 1 are operated. In the intermediate transfer body 1, the surface facing the ink jet device 3 is the first surface, and the surface in contact with the sponge roller 2 is the second surface. The blower 4 reduces the amount of liquid in the intermediate image on the intermediate transfer member 1 by blowing air and the heater 5 disposed on the back side of the intermediate transfer member 1 by heating. As a result, the liquid component in the intermediate image is dried, and the disturbance of the image during transfer is suppressed. In the pressure roller 7, the intermediate image formed on the intermediate transfer body 1 is brought into contact with the recording medium 6 to transfer and form the intermediate image on the recording medium 6. In each example, aurora coated paper made from Nippon Paper Industries was used as the recording medium 6. The cleaning unit 8 is configured to intermittently contact the first surface of the intermediate transfer body 1 with a Molton roller that is always wetted by ion-exchanged water. In the cleaning unit 8, the intermediate transfer body 1 after transferring the intermediate image to the recording medium 6 can be cleaned and repeatedly used for the next image formation.

  As a material for the intermediate transfer member 1, an aluminum plate having a thickness of 0.3 mm was used. In each example, the method for producing the intermediate transfer member 1, the surface treatment, the pore diameter, and the pitch between the pore diameters were changed. More specifically, after forming pores in the aluminum plate by the production method shown in Table 1, only Examples 2 to 4 were subjected to water repellent treatment using a fluorine-based mold release agent (HD-1100 manufactured by Harves). Then, an intermediate transfer member of each example was produced.

  In Comparative Example 1, the same apparatus as that of FIG. 1 was used except that the sponge roller 2 was in contact with the first surface side of the intermediate transfer member 1 and the intermediate transfer member 1 did not have pores.

  A method for producing pores in the intermediate transfer member of each example will be described below.

[Examples 1 to 3]
Using a laser processing apparatus (manufactured by Subaru Optoelectronic Co., Ltd.), pores having the diameters and pitches shown in Table 1 were formed on an aluminum plate having a thickness of 0.3 mm. In addition, about the pattern of each produced Examples 1-3, nine visual fields were observed at 5000-times multiplication factor using the scanning electron microscope (S-4300 by Hitachi, Ltd.), image analysis was performed, and pore diameter And the maximum value of pore diameter was measured. The pitch between the pores was measured by analyzing the image using the same image, determining the center position of each pore, and measuring the pitch between the pores.

[Example 4]
An aluminum plate having a purity of 99.99% and a thickness of 0.3 mm was electropolished to give a mirror surface, and then the sample was placed in a 0.3 M oxalic acid aqueous solution (liquid temperature 17 ° C.) under a direct current of 40 V for 30 minutes. Oxidation treatment was performed. Thereafter, the portion of the bottom of the anodized layer that was not anodized was removed by dry etching using Ar ion milling to form pores having a pore diameter of 0.08 μm and a pitch of 0.1 μm.

  In addition, about the produced pattern, nine visual fields were observed using the scanning electron microscope at the magnification of 70,000 times, the image analysis was performed, and the maximum value of the pore diameter and the pore diameter was measured. The pitch between the pores was measured by analyzing the image using the same image, determining the center position of each pore, and measuring the pitch between the pores.

[Comparative Example 1]
An aluminum plate having a thickness of 0.3 mm that was not subjected to surface treatment or water repellent treatment was used.

  Table 1 shows the production method, surface treatment, pore diameter, and pitch between pore diameters of the intermediate transfer member 1 used in each example and comparative example.

In each example, image recording was performed as follows using the apparatus of FIG. First, a reaction solution was applied to the back surface (second surface) side of the intermediate transfer body 1 (reaction solution applying step). Specifically, the reaction liquid was applied to the back side of the intermediate transfer member 1 by the sponge roller 2. Since Comparative Example 1 does not have pores and the reaction liquid cannot be applied from the back surface, the sponge roller 2 is disposed on the first surface side of the intermediate transfer body 1 and the reaction liquid is transferred to the first surface of the intermediate transfer body 1. 1 was applied directly to the surface of 1. As the reaction solution, components having the following composition were prepared and used.
-10 parts of glutaric acid-30 parts of diethylene glycol-1 part of acetylenol E100-59 parts of ion-exchanged water.

  In Examples 1 to 4, the reaction solution passed through the pores of the intermediate transfer member 1 and moved to the first surface side of the intermediate transfer member 1.

  Next, in Examples 1 to 4 and Comparative Example 1, the first transfer of the intermediate transfer body 1 to which the reaction liquid was applied by the ink jet recording apparatus 3 (nozzle arrangement density 1200 dpi, discharge amount 4.8 pl, drive frequency 12 kHz). Ink was applied on the surface. As a result, a mirror-inverted character image was formed on the intermediate transfer body 1 (intermediate image forming step). Here, inks having the following prescription (four color inks each containing a color pigment as a coloring material) were used.

(Ink formulation)
Each of the following pigments: 3 parts Black: Carbon black (Mitsubishi Chemical Corporation: MCF88)
Cyan: Pigment Blue 15
Magenta: Pigment Red 7
Yellow: Pigment Yellow 74
Styrene-acrylic acid-ethyl acrylate copolymer: 1 part glycerin: 10 parts ethylene glycol: 5 parts Surfactant: 1 part (manufactured by Kawaken Fine Chemicals: acetylenol EH)
Ion exchange water: 80 parts.

  Thereafter, after the liquid content in the intermediate image was removed by the blower 4 and the heater 5, the intermediate image on the intermediate transfer body 1 was transferred to the recording medium 6 by the pressure roller 7 (transfer process). Next, the surface of the intermediate transfer member 1 was cleaned by the cleaning unit 8. In addition, it was 30-35 micrometers when the dot diameter of the ink on the intermediate transfer body 1 in each Example and a comparative example was measured with the optical microscope.

(Image evaluation)
In each example and comparative example, the quality of an image formed on the recording medium 6 by the above-described image recording method was evaluated. The image quality was evaluated by sensory evaluation by a plurality of evaluators. The evaluation criteria are shown below, and the evaluation results are shown in Table 2.
Image quality evaluation criteria A: 90% or more of the evaluators evaluated as preferable ○: 70% to less than 90% of the evaluators evaluated as preferable Δ: 50% to less than 70% of the evaluators evaluated as preferable ×: preferable Less than 50% of the evaluators evaluated.

  As shown in Table 2, in Examples 1 to 4, good image quality was obtained, whereas in Comparative Example 1, the image quality was poor. Further, the transferability of the intermediate image was good in any of Examples and Comparative Examples.

DESCRIPTION OF SYMBOLS 1 Intermediate transfer body 2 Sponge roller 3 Inkjet device 4 Blower 5 Heater 6 Recording medium 7 Pressure roller 8 Cleaning unit 9 Conveying drums 21 and 31 Intermediate transfer body 22 and 52 Ink droplets 23 and 32 Reaction liquids 41 and 51 Fine holes

Claims (6)

A reaction solution applying step for applying a reaction solution to the intermediate transfer member, an intermediate image forming step for forming an intermediate image by applying ink to the intermediate transfer member to which the reaction solution is applied, and transferring the intermediate image to a recording medium. An image recording method comprising:
The intermediate transfer member has a first surface and a second surface opposite to the first surface opposite to the first surface;
The intermediate transfer member has pores penetrating the intermediate transfer member from the first surface to the second surface;
In the reaction liquid application step, the reaction liquid is applied to the second surface, the reaction liquid is moved from the second surface to the first surface through the pores,
In the intermediate image forming step, an ink is applied onto the first surface of the intermediate transfer member.   The image recording method according to claim 1, wherein the first surface of the intermediate transfer member is formed of a water-repellent material or is subjected to a water-repellent treatment.   3. The image recording method according to claim 1, wherein the maximum value of the pore diameter on the first surface of the intermediate transfer member is equal to or less than the diameter of the dot of the ink.   4. The image according to claim 1, wherein a diameter of a maximum circumscribed circle in contact with each pore on the first surface is equal to or less than a diameter of the dot of the ink. 5. Recording method. On the first surface, the pores are distributed so as to have a substantially hexagonal close-packed arrangement, and the pitch between the pores on the first surface is a, the pore diameter is r, and the diameter of the ink dots. Is R,
a <√3 (R + r) / 2
The image recording method according to claim 1, wherein:   The image recording method according to claim 1, wherein the material of the intermediate transfer member is aluminum, and the pores of the intermediate transfer member are formed by anodizing treatment of aluminum. .

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