JP2009119723A - Inkjet image forming method and forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet image forming method and forming apparatus ensuring excellent transfer property by preventing image contraction and sticking of a coloring material even if dropping ink on an impermeable medium. <P>SOLUTION: The inkjet image forming method has a polymer layer forming process for forming a polymer layer 12 by applying, on an intermediate transfer medium 10, polyalkylene glycol, polyalkylene glycol ester or polyoxyalkylene glycol ester serving as material for forming the polymer layer; a coagulating liquid applying process for applying a coagulating liquid 14 for coagulating the ink on the polymer layer 12; an ink dropping process for dropping the ink 16 on the coagulating liquid 14 to form an ink aggregate 18; an ink solvent removing process for removing a solvent in the ink aggregate 18; and a transfer process for carrying out hot pressing transfer of the ink aggregate 18 to a recording medium 22. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inkjet image forming method and apparatus, and more particularly to an inkjet image forming method and apparatus for transferring an image after forming an image on an intermediate transfer medium having a polyalkylene glycol layer or the like formed thereon.

  The ink jet recording system has been applied to various uses as image quality is improved, and the ink jet recording medium uses dedicated paper in order to provide ink acceptability. However, there are many types of dedicated paper used for printing paper such as color tone, gloss, and thickness, and it has been difficult to prepare all corresponding ink-jet paper. Therefore, as a measure for various papers, a method of once forming an inkjet image on an intermediate transfer medium for inkjet, and then transferring the transfer layer on which the image is recorded to a transfer material such as a printing sheet as a final recording medium Has been proposed.

  However, when ink is ejected onto the intermediate transfer medium, if the dots are successively deposited adjacent to each other, the ink droplets on the intermediate transfer medium are united by the surface tension to form a desired dot. There was a problem of bleed (landing interference) that could not be formed. In the case of dots of the same color, the dot shape collapses, and in the case of dots between different colors, a problem of color mixing also occurs.

  Therefore, in Patent Document 1 below, one of the aggregating treatment liquid (liquid composition) and the ink is made acidic and the other is made alkaline to control the pigment agglomeration on the paper surface, resulting in optical density / bleeding / bleeding. (Time bleeding)-A technique for improving the drying time is disclosed.

Further, in Patent Document 2 below, high-speed recording can be performed without bleeding by providing a powder layer (water-soluble resin layer) that can be swollen, thickened, and peeled by reaction with ink on an intermediate transfer medium. A possible recording method is disclosed.
JP 2004-10633 A Japanese Patent Laid-Open No. 11-188858

  However, in the method described in Patent Document 1, when ink is deposited on an impermeable medium such as a plastic sheet after the ink is deposited, the landed and aggregated colorant is in a desired position. It will move without staying at. As a result, there arises a new problem that the output image is greatly disturbed compared to the desired image.

  Further, the method of Patent Document 2 has the following problems. (1) Since the color material in the ink is not actively aggregated, if the ink droplet is ejected at a high speed of 10 kHz or more, the swelling / thickening is not in time, and the above-described landing interference occurs. (2) Since the transferred image forming layer swells and absorbs the ink solvent, there is a so-called pile height problem that the thickness of the image portion is increased. When the image thickness increases, not only the image quality problem that the appearance of the boundary between the printed part and the non-printed part changes, but also a problem that a step is felt when the part is touched. . (3) Since the ink solvent is absorbed in the transferred image forming layer, the ink solvent oozes out to the paper surface after the transfer, and paper deformation (so-called cockling) occurs. The above (2) and (3) are problems that occur because an image is formed on the final recording medium (paper) while containing the ink solvent. In addition, the above (1) to (3) are fatal image degradations in high-quality printing.

  The present invention has been made in view of such circumstances, and even when ink is deposited on a non-permeable medium, image shrinkage can be prevented, and coloring material adhesion during transfer can be prevented. An inkjet image forming method and a forming apparatus capable of ensuring transferability are provided.

  According to a first aspect of the present invention, in order to achieve the above object, a polyalkylene glycol, a polyalkylene glycol ester or a polyoxyalkylene glycol ester is applied as a material for forming a polymer layer on an intermediate transfer medium, and the polymer layer Forming a polymer layer, applying a liquid aggregation treatment liquid to agglomerate ink on the polymer layer, and ink corresponding to an image signal on the aggregation treatment liquid An ink droplet ejection step for forming ink aggregates by droplets, an ink solvent removal step for removing the solvent in the ink aggregates, and the ink aggregates formed on the intermediate transfer medium on a recording medium. There is provided a method for forming an ink jet image having a transfer step for performing heat-pressure transfer.

  According to claim 1, a polyalkylene glycol (hereinafter also referred to as “PAG”), a polyalkylene glycol ester, or a polyoxyalkylene glycol ester (hereinafter also referred to as “PAG etc.”) is applied onto the intermediate transfer medium, After the polymer layer is formed, ink is ejected. PAG, etc. has a surface energy higher than that of a commonly used intermediate transfer medium, that is, wettability, so that the ink aggregates adhere to the intermediate transfer medium coated with PAG, etc., and sufficient adhesion is achieved. Can be obtained. Accordingly, it is possible to suppress the image shrinkage of the ink on the intermediate transfer medium.

  Further, when transferring the ink to the recording medium, the transfer is performed by applying heat. When the temperature of PAG or the like is low, even if the wettability of PAG or the like with respect to the intermediate transfer medium is poor, the viscosity is high, so PAG or the like is attached to the intermediate transfer medium. Since it becomes difficult to adhere to the intermediate transfer medium, the ink can be peeled off onto the recording medium together with the PAG and transferred.

  A second aspect of the present invention is characterized in that, in the first aspect, after the aggregation treatment liquid coating step, a coagulation treatment liquid drying step of drying the aggregation treatment liquid is provided.

  According to the second aspect, after the aggregation treatment liquid application step, the aggregation treatment liquid is dried to form a solid or semi-solid solution treatment layer. Accordingly, the ink applied in the next step can be easily separated into the pigment aggregate and the solvent, and the solvent can be absorbed and removed using the solvent absorbing roller. In addition, it is possible to prevent the pigment aggregate from adhering to the solvent absorbing roller.

The “solid or semi-solid aggregation treatment layer (aggregation treatment agent)” refers to a layer having a moisture content of 0 to 70% in the aggregation treatment layer (aggregation treatment agent). The “water content” is a ratio of the weight X ₂ [g / m ³ ] per unit volume of water contained in the aggregation treatment layer to the weight X ₁ [g / m ³ ] per unit volume of the aggregation treatment layer. (Ie, X ₂ / X ₁ ).

  According to a third aspect of the present invention, in order to achieve the above object, a polyalkylene glycol, a polyalkylene glycol ester or a polyoxyalkylene glycol ester is applied as a material for forming a polymer layer on an intermediate transfer medium, A polymer layer forming step for forming a layer, an ink droplet ejection step for depositing ink according to an image signal on the polymer layer, and a liquid aggregation treatment liquid for aggregating the ink on the ink An aggregating treatment liquid applying step for forming an ink aggregate by coating, an ink solvent removing step for removing a solvent in the ink aggregate, and the ink aggregate formed on the intermediate transfer medium are heated on a recording medium. And a transfer step of performing pressure transfer.

  According to the third aspect, after the ink is ejected, the aggregation treatment liquid is applied. In the present invention, since ink is ejected onto a polymer layer such as a PAG, the wettability is good, and the ink does not repel on the polymer layer, so that image shrinkage can be suppressed. Therefore, the effect of the present invention can be obtained even if the order of the ink droplet ejection step and the aggregation treatment liquid application step is changed.

  A fourth aspect of the present invention is characterized in that in any one of the first to third aspects, the polyalkylene glycol, polyalkylene glycol ester, or polyoxyalkylene glycol ester is in the form of a wax.

  According to the fourth aspect, since a highly viscous PAG or the like can be used by using a wax-like PAG or the like, it is possible to ensure high adhesion between the intermediate transfer medium and the PAG or the like without applying a temperature. it can.

  A fifth aspect of the present invention is characterized in that in any one of the first to fourth aspects, the material forming the polymer layer is a polyalkylene glycol ester or a polyalkylene glycol ether.

  In the present invention, by using a polyalkylene glycol ester or polyoxyalkylene glycol ether as a material for forming the polymer layer, it is possible to fix the ink aggregate on the polymer layer particularly effectively.

  A sixth aspect is characterized in that, in any one of the first to fifth aspects, the surface energy of the polymer layer at room temperature is 25 mN / m or more.

  According to the sixth aspect of the present invention, when the surface energy of the polymer layer at room temperature, that is, the surface energy of PAG or the like is 25 mN / m or more, the spread of the ink can be prevented. Therefore, it is possible to prevent the ink from spreading from a desired image ejected by inkjet.

  According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the ink is ejected onto the polymer layer having a melting temperature or lower.

  According to claim 7, by setting the temperature of the polymer layer to be equal to or lower than the melting temperature of the PAG or the like, the polymer layer can be adhered to the substrate due to viscosity or the like, and the ink is maintained in a desired image. can do. If the melting temperature is higher than the temperature of PAG or the like, the polymer layer dissolves and loses its viscosity, so that it may flow on the intermediate transfer medium, and the ejected ink cannot maintain the desired image.

  According to an eighth aspect of the present invention, in order to achieve the above object, a polyalkylene glycol, a polyalkylene glycol ester or a polyoxyalkylene glycol ester is applied as a material for forming a polymer layer on an intermediate transfer medium, A polymer layer forming means for forming a layer, an aggregating treatment liquid applying means for applying a liquid aggregating treatment liquid for aggregating ink on the polymer layer, and an image signal on the aggregating treatment liquid according to an image signal An ink droplet ejecting unit for ejecting ink to form an ink aggregate, an ink solvent removing unit for removing a solvent in the ink aggregate, and the ink aggregate formed on the intermediate transfer medium are recorded on a recording medium. And an ink jet image forming apparatus provided with a transfer means for performing thermal pressure transfer.

  A ninth aspect of the present invention is characterized in that, in the eighth aspect, an aggregating treatment liquid drying unit for drying the aggregating treatment liquid is provided after the aggregating treatment liquid applying unit.

  According to a tenth aspect of the present invention, in order to achieve the above object, a polyalkylene glycol, a polyalkylene glycol ester or a polyoxyalkylene glycol ester is applied as a material for forming a polymer layer on an intermediate transfer medium, A polymer layer forming means for forming a layer, an ink droplet ejecting means for depositing ink according to an image signal on the polymer layer, and a liquid aggregation treatment liquid for aggregating the ink on the ink. An aggregating treatment liquid applying unit that forms an ink aggregate by coating, an ink solvent removing unit that removes a solvent in the ink aggregate, and the ink aggregate formed on the intermediate transfer medium are heated on a recording medium. There is provided an inkjet image forming apparatus including a transfer unit that performs pressure transfer.

  The eighth to tenth aspects are obtained by developing the inkjet image forming method according to the first to third aspects as an inkjet image forming apparatus. According to claims 8 to 10, the same effects as those of claims 1 to 3 can be obtained.

  According to the present invention, since ink is ejected after applying PAG or the like on the intermediate transfer medium, the wettability is higher than that of a commonly used intermediate transfer medium, and image shrinkage can be prevented. In addition, since the transfer is performed by applying heat to the recording medium, the polymer layer is dissolved by changing the heat and the effect of adhesion to the intermediate transfer medium is lost due to viscosity or the like. The ink can be transferred to the recording medium together with the polymer layer by repelling the layer. As described above, it is possible to provide an ink jet image forming method and a forming apparatus that can achieve both ink fixability when ink is ejected and ink releasability when transferred.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

First, inks used in the present invention, aggregating treatment liquid (hereinafter also simply referred to as “processing machine liquid”), polyalkylene glycol, polyalkylene glycol ester, and polyoxyalkylene glycol ether will be described, and then the ink jet according to the present invention. An image forming method and an inkjet image forming apparatus will be described.
[Description of ink]
The ink used in the present invention is a water-based pigment ink containing a pigment that is a coloring material (coloring agent) or polymer fine particles as a solvent-insoluble material.

  The concentration of the solvent-insoluble material is preferably 1 wt% or more and 20 wt% or less considering a viscosity of 20 mPa · s or less suitable for ejection. More preferably, the pigment concentration is 4 wt% or more in order to obtain the optical density of the image.

  The surface tension of the ink is preferably 20 mN / m or more and 40 mN / m in consideration of ejection stability.

  The color material used in the ink can be a pigment or a mixture of a dye and a pigment. From the viewpoint of aggregability at the time of contact with the treatment liquid, a pigment in a dispersed state in the ink is preferable because it aggregates more effectively. Among the pigments, a pigment dispersed by a dispersant, a self-dispersing pigment, a pigment whose surface is coated with a resin (microcapsule pigment), and a polymer graft pigment are particularly preferable. From the viewpoint of pigment aggregation, a form modified with a carboxyl group having a low dissociation degree is more preferable.

  The resin of the microcapsule pigment is not limited, but is preferably a high molecular compound having a self-dispersibility or solubility in water and an anionic group (acidic). This resin usually has a number average molecular weight of about 1,000 to 100,000, and particularly preferably about 3,000 to 50,000. Further, it is preferable that this resin is dissolved in an organic solvent to form a solution. When the number average molecular weight of the resin is within this range, the function as a coating film in the pigment or as a coating film in the ink composition can be sufficiently exhibited.

  The resin may be self-dispersible or soluble, or may have a function added by some means. For example, it may be a resin in which an anionic group such as a carboxyl group, a sulfonic acid group, or a phosphonic acid group is introduced by neutralization with an organic amine or an alkali metal. Further, it may be a resin into which one or two or more anionic groups of the same type or different types are introduced. In the present invention, a resin in which a carboxyl group is introduced by neutralization with a base is preferably used.

  Although it does not specifically limit as a pigment used for this invention, As a specific example, as a pigment for orange or yellow, C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185. Examples of red or magenta pigments include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Examples of black pigments include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

  In the colored ink liquid according to the present invention, it is preferable to add polymer fine particles not containing a colorant as a component that reacts with the treatment liquid. The polymer fine particles can enhance the thickening action and aggregation action of the ink by reaction with the treatment liquid, and can improve the image quality. In particular, a highly safe ink can be obtained by incorporating anionic polymer fine particles into the ink.

  By using polymer fine particles that react with the treatment liquid and cause thickening and aggregating action in the ink, the quality of the image can be improved. At the same time, depending on the type of polymer fine particles, the polymer fine particles form a film on the recording medium. It also has the effect of improving the scratch resistance and water resistance of the image.

  The dispersion method in the polymer ink is not limited to emulsion, and it may be dissolved or exist in a colloidal dispersion state.

  The polymer fine particles may be obtained by dispersing the polymer fine particles using an emulsifier, or may be dispersed without using an emulsifier. As the emulsifier, a low molecular weight surfactant is usually used, but a high molecular weight surfactant can also be used as an emulsifier. It is also preferable to use capsule type polymer fine particles (core / shell type polymer fine particles having different compositions at the center and outer edge of the particle) whose outer shell is made of acrylic acid, methacrylic acid or the like.

  As a dispersion method, polymer fine particles not using a low molecular weight surfactant are called soap-free latex, including polymer fine particles using a high molecular weight surfactant and polymer fine particles not using an emulsifier. For example, a polymer having a water-soluble group such as a sulfonic acid group or a carboxylic acid group described above (a polymer in which a solubilizing group is graft-bonded, a monomer having a solubilizing group, and an insoluble portion) Polymer fine particles using a block polymer obtained from a monomer as an emulsifier are also included.

  In the present invention, it is particularly preferable to use this soap-free latex. The soap-free latex, compared with polymer fine particles polymerized using a conventional emulsifier, inhibits the reaction aggregation and film formation of the polymer fine particles, or the free emulsifier. However, it moves to the surface after forming the polymer fine particles, and there is no concern that the adhesiveness between the aggregate in which the pigment and the polymer fine particles are mixed and the recording medium is lowered.

  Examples of the resin component added to the ink as polymer fine particles include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, styrene resins, and the like.

  From the viewpoint of imparting high-speed cohesiveness to the polymer fine particles, those having a carboxylic acid group having a low dissociation degree are more preferable. Since the carboxylic acid group is easily affected by pH change, the dispersion state is easily changed and the cohesiveness is high.

  The change of the dispersion state with respect to the pH change of the polymer fine particles can be adjusted by the content ratio of the constituent component in the polymer fine particles having a carboxylic acid group such as an acrylate ester, and the like depending on the anionic surfactant used as the dispersant. Can also be adjusted.

  The resin component of the polymer fine particles is preferably a polymer having both a hydrophilic portion and a hydrophobic portion. By having the hydrophobic portion, the hydrophobic portion is oriented inside the polymer fine particle, the hydrophilic portion is efficiently oriented outside, and the effect of increasing the dispersion state with respect to the pH change of the liquid is greater, and aggregation is caused. Done more efficiently.

  The acid polymer used in the present invention is preferably a carboxylic acid acid polymer.

  Since the pKa of the carboxylic acid is approximately 3 to 4, the acid polymer is almost dissociated at pH 5, so that it has dispersion stability and does not cause aggregation due to electric repulsion. If it is less than this, it will be in a non-dissociated state, the electric repulsion will be lost, and aggregation will occur.

  Examples of commercially available polymer fine particles include Jonkrill 537, 7640 (styrene-acrylic resin emulsion, manufactured by Johnson Polymer Co., Ltd.), Microgel E-1002, E-5002 (styrene-acrylic resin emulsion, Nippon Paint Co., Ltd.). Manufactured), Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), SAE-1014 (styrene-acrylic resin) Emulsion, manufactured by Nippon Zeon Co., Ltd., Jurimer ET-410, FC-30 (acrylic resin emulsion, manufactured by Nippon Pure Chemicals Co., Ltd.), Aron HD-5, A-104 (acrylic resin emulsion, manufactured by Toagosei Co., Ltd.) ), Cybino Le SK-200 (acrylic resin emulsion, manufactured by Saiden Chemical Industry Co., Ltd.), Zaikthene L (acrylic resin emulsion, manufactured by Sumitomo Seika Chemicals Co., Ltd.) and the like, not limited to this.

  The weight ratio of the polymer fine particle addition amount to the pigment is preferably 2: 1 to 1:10, more preferably 1: 1 to 1: 3. If the weight ratio of the amount of polymer fine particles added to the pigment is less than 2: 1, the cohesive force of the aggregate due to resin fusion will not be improved effectively. Moreover, even if the addition amount is more than 1:10, the viscosity of the ink becomes too high, and the discharge properties and the like deteriorate.

  The molecular weight of the polymer fine particles added to the ink is preferably 5,000 or more in view of the adhesive force when fused. If it is less than 5,000, the effect of improving the internal cohesive force of the ink aggregate when aggregated, fixing the image on the recording medium, and the effect of improving the image quality are insufficient.

  The volume average particle diameter of the polymer fine particles is preferably in the range of 10 nm to 1 μm, more preferably in the range of 10 to 500 nm, still more preferably in the range of 20 to 200 nm, and particularly preferably in the range of 50 to 200 nm. If the thickness is 10 nm or less, the effect of improving the image quality and the improvement of transferability cannot be expected even if they are aggregated. When the thickness is 1 μm or more, there is a concern that the ejection properties of the ink from the head and the storage stability may deteriorate. Moreover, there is no restriction | limiting in particular regarding the volume average particle diameter distribution of a polymer particle, What has a wide volume average particle diameter distribution or a thing with a monodispersed volume average particle diameter distribution may be sufficient.

  Further, two or more kinds of polymer fine particles may be mixed and used in the ink.

  As a pH adjuster added to the ink used in the present invention, an organic base or an inorganic alkali base can be used as a neutralizing agent. The pH adjusting agent is preferably added so that the inkjet ink has a pH of 6 to 10 for the purpose of improving the storage stability of the inkjet ink.

  The ink used in the present invention preferably contains a water-soluble organic solvent for the purpose of preventing clogging of the nozzles of the inkjet head due to drying. Such water-soluble organic solvents include wetting agents and penetrants.

  Examples of the water-soluble organic solvent include polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, alcohols, sulfur-containing solvents and the like, as in the case of the treatment liquid. Specific examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, and glycerin. Examples of polyhydric alcohol derivatives include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and diglycerin. Examples include ethylene oxide adducts. Examples of nitrogen-containing solvents include pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, and triethanolamine. Examples of alcohols include alcohols such as ethanol, isopropyl alcohol, butyl alcohol, and benzyl alcohol. Thiodiethanol, thiodiglycerol, sulfolane, dimethyl sulfoxide and the like. In addition, propylene carbonate, ethylene carbonate, or the like can be used.

  The ink used in the present invention can contain a surfactant.

  Examples of surfactants include fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonate formalin condensates, Anionic surfactants such as oxyethylene alkyl sulfate esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylamines Nonionic surfactants such as glycerin fatty acid ester and oxyethyleneoxypropylene block copolymer are preferred. Further, SURFYNOLS (Air Products & Chemicals), which is an acetylene-based polyoxyethylene oxide surfactant, is also preferably used. An amine oxide type amphoteric surfactant such as N, N-dimethyl-N-alkylamine oxide is also preferred.

  Further, pages (37) to (38) of JP-A-59-157636, Research Disclosure No. The surfactants described in 308119 (1989) can also be used. In addition, fluorine (fluorinated alkyl) and silicone surfactants as described in JP-A Nos. 2003-322926, 2004-325707, and 2004-309806 are also used. Can do. These surface tension modifiers can also be used as antifoaming agents, and fluorine-based, silicone-based compounds, chelating agents represented by EDTA, and the like can also be used.

  The surface tension can be lowered to increase the wettability on the solid or semi-solid agglomerated layer, and the spreading rate can be increased.

  The surface tension of the ink used in the present invention is 15 to 45 mN / from the viewpoint of compatibility between the wettability on the intermediate transfer medium and the formation of fine droplets and ejection when performing recording by the intermediate transfer method. More preferably, it is m.

  The viscosity of the ink used in the present invention is preferably 1.0 to 20.0 cP.

In addition, a pH buffer, an antioxidant, a fungicide, a viscosity modifier, a conductive agent, an ultraviolet absorber, and the like can be added as necessary.
[Description of treatment liquid (aggregation treatment liquid)]
The treatment liquid according to the present invention is preferably a treatment liquid that aggregates pigments and polymer fine particles contained in the ink by changing the pH of the ink, thereby generating an aggregate.

  Treatment liquid components include polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, orthophosphoric acid, pyrrolidone It is preferably selected from carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, or salts thereof.

  A preferable example of the treatment liquid according to the present invention is a treatment liquid to which a polyvalent metal salt or polyallylamine is added. These compounds may be used alone or in combination of two or more.

  The treatment liquid according to the present invention preferably has a pH of 1 to 6, more preferably 2 to 5, and particularly preferably 3 to 5 from the viewpoint of pH aggregation performance with the ink. .

  In the treatment liquid according to the present invention, the addition amount of the component for aggregating the pigment and polymer fine particles of the ink is preferably 0.01% by weight or more and 20% by weight or less with respect to the total weight of the liquid. When the amount is 0.01% by weight or less, concentration dispersion does not proceed sufficiently when the treatment liquid and the ink are in contact with each other, and an agglomeration effect due to pH change may not occur sufficiently. On the other hand, if it is 20% by weight or more, the dischargeability from the ink jet head may deteriorate.

  The treatment liquid according to the present invention preferably contains water and other additive-soluble organic solvents for the purpose of preventing clogging of the nozzles of the inkjet head due to drying. Such water and other additive-soluble organic solvents include wetting agents and penetrants.

  These solvents can be used alone or in combination with water and other additives.

  The content of water and other additive-soluble organic solvents is preferably 60% by weight or less based on the total weight of the treatment liquid. When the amount is more than 60% by weight or more, the viscosity of the treatment liquid increases, and the dischargeability from the inkjet head may deteriorate.

  The treatment liquid may further contain a resin component in order to improve fixability and abrasion resistance. The resin component may be any resin component that does not impair the ejection properties from the head when the treatment liquid is ejected by the ink jet method and has storage stability, and water-soluble resins and resin emulsions can be used freely.

  Examples of the resin component include acrylic, urethane, polyester, vinyl, and styrene. In order to sufficiently develop the function of improving the fixing property, it is necessary to add a relatively high polymer to a high concentration of 1% by weight to 20% by weight. However, if it is attempted to dissolve the above material in a liquid and add it, the viscosity becomes high, and the discharge property is lowered. In order to add an appropriate material at a high concentration and suppress an increase in viscosity, a means of adding as a latex is effective. Latex materials include alkyl acrylate copolymers, carboxy-modified SBR (styrene-butadiene latex), SIR (styrene-isoprene) latex, MBR (methyl methacrylate-butadiene latex), NBR (acrylonitrile-butadiene latex), and the like. Conceivable. The glass transition point Tg of the latex is a value that has a strong influence upon fixing in the process, and is preferably 50 ° C. or higher and 120 ° C. or lower in order to achieve both stability at room temperature storage and transferability after heating. Further, the minimum film-forming temperature MFT is a value that has a strong influence upon fixing in the process, and is 100 ° C. or lower, more preferably 50 ° C. or lower in order to obtain sufficient fixing at a low temperature.

  The coagulability may be further enhanced by adding polymer fine particles having a polarity opposite to that of the ink to the treatment liquid and aggregating with the pigment and polymer fine particles in the ink.

  In addition, a curing agent corresponding to the polymer fine particle component contained in the ink is contained in the treatment liquid, and after the two liquids contact, the resin emulsion in the ink component aggregates and crosslinks or polymerizes to increase the cohesiveness. Also good.

  The treatment liquid used in the present invention can contain a surfactant.

  Examples of surfactants include fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonate formalin condensates, Anionic surfactants such as oxyethylene alkyl sulfate esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylamines Nonionic surfactants such as glycerin fatty acid ester and oxyethyleneoxypropylene block copolymer are preferred. Further, SURFYNOLS (Air Products & Chemicals), which is an acetylene-based polyoxyethylene oxide surfactant, is also preferably used. An amine oxide type amphoteric surfactant such as N, N-dimethyl-N-alkylamine oxide is also preferred.

  Further, pages (37) to (38) of JP-A-59-157636, Research Disclosure No. The surfactants described in 308119 (1989) can also be used. In addition, fluorine (fluorinated alkyl) and silicone surfactants as described in JP-A Nos. 2003-322926, 2004-325707, and 2004-309806 are also used. Can do. These surface tension modifiers can also be used as antifoaming agents, and fluorine-based, silicone-based compounds, chelating agents represented by EDTA, and the like can also be used.

  This is effective in reducing the surface tension and improving the wettability on the image forming body (intermediate transfer medium). Further, even when ink is ejected in advance, the wettability on the ink is enhanced, and the cohesive action is effectively promoted by increasing the contact area of the two liquids.

  The surface tension of the treatment liquid according to the present invention is preferably 10 to 50 mN / m, and from the viewpoint of achieving both wettability on the intermediate transfer medium, droplet formation and ejection properties, 15 More preferably, it is -45 mN / m.

  The viscosity of the treatment liquid used in the present invention is preferably 1.0 to 20.0 cP.

In addition, pH buffering agents, antioxidants, fungicides, viscosity modifiers, conductive agents, ultraviolet rays, absorbents, and the like can be added as necessary.
[Description of polyalkylene glycol, polyalkylene glycol ester, polyoxyalkylene glycol ether]
In the present invention, polyalkylene glycol, polyalkylene glycol ester, and polyoxyalkylene glycol ether are used as a material for forming the polymer layer. Of these, polyalkylene glycol esters and polyoxyalkylene glycol ethers are particularly preferably used.

  The polyalkylene glycol is not particularly limited and can be used, and specific examples include polyethylene glycol, polypropylene glycol diol type, polypropylene glycol triol type, and polybutylene glycol. The repeating unit of the alkylene chain is preferably 2 to 100,000, more preferably 4 to 500, and particularly preferably 20 to 100. Specific examples include polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 1000, polyethylene glycol 1540, polyethylene glycol 2000, polyethylene glycol 3400, polyethylene glycol 4000, polyethylene glycol 6000, polyethylene glycol 8000, polyethylene. Examples include glycol 20000, polyethylene glycol 500000, polyethylene glycol 3500000, polypropylene glycol diol type average molecular weight 700, 1000, 2000, 3000, polypropylene glycol triol type average molecular weight 300, 700, 1500, 3000, 4000, and the like. Polyalkylene glycols particularly preferably used are polyethylene glycol 1000, polyethylene glycol 1540, polyethylene glycol 2000, and polyethylene glycol 3400.

  The polyalkylene glycol ester is not particularly limited and can be used. Specifically, polyethylene glycol monostearate, polyethylene glycol monooleate, polyethylene glycol monolaurate, polyethylene glycol monosaccharate, polyethylene glycol monononylpheny Rate, polyethylene glycol monooctylate, polyethylene glycol monooctyl phenylate, polyethylene glycol monocetylate and the like. Among these, polyethylene glycol monostearate and polyethylene glycol monooleate are preferable, and the repeating unit of the alkylene chain is preferably 2 to 500, particularly preferably 15 to 60.

  Specific examples include polyethylene glycol monostearate n = 2, polyethylene glycol monostearate n = 4, polyethylene glycol monostearate n = 10, polyethylene glycol monostearate n = 25, polyethylene glycol monostearate n = 40, Polyethylene glycol monostearate n = 45, polyethylene glycol monostearate n = 55, polyethylene glycol monooleate n = 2, polyethylene glycol monooleate n = 7, polyethylene glycol monooleate n = 10, polyethylene glycol monooleate n = 20, Polyethylene glycol monooleate n = 50, polyethylene glycol monolaurate n = 10, polyethylene glycol monolaurate n = 25, polyethylene Glycol monononyl phenylate n = 2, polyethylene glycol monononyl phenylate n = 5, polyethylene glycol monononyl phenylate n = 7.5, polyethylene glycol monononyl phenylate n = 10, polyethylene glycol monononyl phenylate n = 15 Polyethylene glycol monononyl phenylate n = 18, polyethylene glycol monononyl phenylate n = 20, polyethylene glycol monooctyl n = 23, polyethylene glycol monooctyl phenylate n = 10, polyethylene glycol monocetylate n = 23, etc. Polyethylene glycol monostearate n = 25, polyethylene glycol monostearate n = 40, polyethylene glycol monostearate n = 4 , Polyethylene glycol monostearate n = 55, polyethylene glycol monooleate n = 20, such as polyethylene glycol monooleate n = 50 being particularly preferred.

  The polyoxyalkylene ether of the present invention is not particularly limited and can be used, but polyoxyethylene ether is preferably used. Examples include polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene docosyl ether, polyoxyethylene dodecyl ether, polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, and the like. Specifically, polyoxyethylene (2) oleyl ether, polyoxyethylene (7) oleyl ether, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, polyoxyethylene (50) oleyl ether, poly Oxyethylene (2) stearyl ether, polyoxyethylene (4) stearyl ether, polyoxyethylene (20) stearyl ether, polyoxyethylene (5) docosyl ether, polyoxyethylene (10) docosyl ether, polyoxyethylene ( 20) docosyl ether, polyoxyethylene (30) docosyl ether, polyoxyethylene (9) dodecyl ether, polyoxyethylene (10) dodecyl ether, polyoxyethylene (9) lauryl ether , Polyoxyethylene (23) lauryl ether, polyoxyethylene (2) nonylphenyl ether, polyoxyethylene (5) nonylphenyl ether, polyoxyethylene (7.5) nonylphenyl ether, polyoxyethylene (9) nonylphenyl Ether, polyoxyethylene (10) nonylphenyl ether, polyoxyethylene (15) nonylphenyl ether, polyoxyethylene (18) nonylphenyl ether, polyoxyethylene (20) nonylphenyl ether, polyoxyethylene (8) octylphenyl Examples include ether, polyoxyethylene (9) octylphenyl ether, polyoxyethylene (10) octylphenyl ether, and the like. Among these, polyoxyethylene (10) oleyl ether, polyoxyethylene (20) oleyl ether, polyoxyethylene (2) stearyl ether, polyoxyethylene (4) stearyl ether, polyoxyethylene (20) stearyl ether, etc. Particularly preferably used.

  Some of these compounds are liquid, wax (WAX), or flakes at room temperature, and among them, a wax (WAX) is particularly preferable because it maintains adhesion to the intermediate transfer medium.

Moreover, polyalkylene glycol, polyalkylene glycol ester, and polyoxyalkylene glycol ester can also be used independently, and 2 or more types can also be mixed and used for them. In addition, pH buffering agents, antioxidants, antifungal agents, viscosity modifiers, conductive agents, ultraviolet rays, absorbents, and the like can be added as necessary, but it is preferable to use them alone.
[Inkjet image forming method]
Next, the inkjet image forming method according to the present invention will be described.

  FIG. 1 is a schematic diagram showing a first embodiment of an inkjet image forming method according to the present invention. In the image forming method according to the present invention, first, a polyalkylene glycol, a polyalkylene glycol ester, and a polyoxyalkylene glycol ether are coated on an intermediate transfer medium (non-penetrable medium) 10 shown in FIG. Is formed (FIG. 1B). As a method of applying polyalkylene glycol, polyalkylene glycol ester, and polyoxyalkylene glycol ether, it is preferable to apply the film on a recording medium with a film thickness of 0.01 to 10 μm using an application roller (application means). A more preferable film thickness is 0.05 to 5 μm, and further preferably 0.1 to 3 μm. The surface energy of the formed polymer layer 12 is preferably 25 mN / m or more at room temperature, more preferably 28 mN / m or more, and further preferably 30 mN / m or more. By setting the surface energy of the polymer layer 12 in the above range, the ink ejected on the polymer layer 12 can be fixed.

  Thereafter, the coagulation treatment liquid is uniformly applied with a film thickness of 0.1 to 30 μm using another application roller (aggregation treatment liquid application means). A more preferable film thickness is 0.5 to 20 μm, and further preferably 1 to 15 μm. Thereafter, the aggregation treatment agent on the polymer layer 12 is dried using a heating means such as a heater to form a solid or semi-solid aggregation treatment layer 14 on the polymer layer (FIG. 1C). ). Examples of the method for drying the aggregating agent include a method using a heating means such as a heater or a method of supplying hot air at about 70 ° C. Further, the aggregation treatment liquid may be ejected selectively with respect to the landing position of the ink droplet by using an ink jet head instead of the application roller. In this case, the amount of solvent in the flocculating agent can be reduced, and the drying time and heating energy can be reduced.

  Next, ink droplets 16 are ejected onto the intermediate transfer medium 10 on which the solid or semi-solid aggregation processing layer 14 is formed (FIG. 1D). In the ink droplet ejection process, CMY inks are ejected from the ink head in accordance with the image signal and ejected. The ink ejection volume is 2 pl, and the recording density is recorded at 1200 dpi in both the main scanning and sub-scanning directions. By forming the solid or semi-solid aggregation treatment layer 14 on the intermediate transfer medium 10 and then ejecting the ink droplets 16, the ink aggregates (spreading to a predetermined size) on the polymer layer 12 ( Dots composed of the color material aggregates 18 are formed (FIG. 1E). At this time, since the WAX-like polymer layer 12 has a surface energy higher than that of the intermediate transfer medium 10, the ink aggregate 18 adheres to the polymer layer 12 and image shrinkage can be suppressed.

  The temperature at which the ink is ejected is preferably below the melting temperature of PAG, which is a material for forming the polymer layer 12. If the temperature is higher than the melting temperature, the polymer layer 12 has fluidity, so that the adhesive force between the polymer layer 12 and the intermediate transfer medium 10 cannot be maintained, and the applied ink maintains a desired image. I can't do that.

  Next, the liquid solvent on the intermediate transfer medium 10 is removed while the ink is separated into the ink aggregate and the liquid solvent by the aggregation reaction. As shown in FIG. 1 (f), the liquid solvent is removed by bringing the solvent absorbing roller 20 whose surface is composed of a porous body (absorber) into contact with the liquid solvent on the intermediate transfer medium 10. A method (solvent absorption method) is applied. As described above, the ink aggregate 18 can obtain a sufficient adhesion force between the polymer layer 12 and the polymer layer 12 and the intermediate transfer medium 10 are adhered due to the viscosity of the polymer layer 12. Therefore, it is possible to absorb and remove the liquid solvent while preventing the coloring material from adhering to the solvent absorbing roller 20. In the present invention, as in this example, a method of removing the liquid solvent on the intermediate transfer medium by absorbing it in an absorber (porous body) is preferable. Adequate adhesion between the ink aggregate, polymer layer and intermediate transfer medium can be obtained, so it is possible to remove a large amount of liquid solvent in a short time while preventing adhesion of the coloring material to the absorber. Thus, print productivity is improved. It is particularly suitable for a two-liquid aggregation type ink jet recording apparatus. Further, by removing the liquid solvent without heating, the viscosity of the polymer layer 12 can be maintained, and the color material can be prevented from adhering to the solvent absorbing roller 20 of the ink aggregate 18.

  Next, the intermediate transfer medium 10 is heated by a heater so as to be 30 to 100 ° C. The heating temperature is set according to the temperature of the polymer resin (fine particles) contained in the ink or treatment liquid.

  Then, the image is transferred from the intermediate transfer medium 10 to the plain paper as the final recording medium 22 by the transfer roller (FIG. 1 (g)). The nip pressure is preferably in the range of 0.5 to 10 MPa. At this time, it is heated by the heater. The polymer layer 12 is dissolved and repels PAG as a raw material on the intermediate transfer medium 10. This is because, when the polymer layer 12 is at a low temperature, it adheres to the intermediate transfer medium 10 due to viscosity or the like even if the wettability is poor. It is. Therefore, the ink aggregate 18 can be transferred to the plain paper (final recording medium) 22 together with the dissolved PAG 24 by performing the thermal pressure transfer.

  Next, the intermediate transfer medium 10 and (final recording medium) 22 are peeled off at the peeling portion (FIG. 1 (h)). At this time, the section from the transfer roller to the peeling portion may be cooled by a cooling member as necessary. Finally, plain paper (final recording medium) 22 is fixed by heating and pressing. The heating temperature is preferably 50 to 200 ° C. and the applied pressure is preferably 0.5 to 10 MPa.

  In this embodiment, the example of plain paper has been described. However, the present invention can be applied to other various media. In this embodiment, the aggregating treatment liquid is applied and dried to form a solid or semi-solid agglomerated layer, but an image can be formed without drying. is there. However, by performing drying, it is possible to form a uniform aggregating treatment layer, suppressing variations in the size of ink aggregates formed by the subsequent agglomeration reaction of ink droplets, and improving image quality be able to. Further, since the ink does not dissolve in the solvent of the aggregation treatment agent, it is possible to suppress the coloring material from adhering to the solvent absorbing roller when the solvent absorbing roller absorbs the liquid solvent.

  FIG. 2 is a schematic diagram showing a second embodiment of the inkjet image forming method of the present invention. The second embodiment is different from the first embodiment in that the ink droplet ejection step (FIG. 2 (c)) for ejecting ink and the aggregation treatment liquid application step (FIG. 2 (d)) for applying the aggregation treatment liquid. The difference is that the order is reversed. The polymer layer forming step (FIG. 2B) and the solvent removal step to the peeling step (FIGS. 2E to 2G) are performed by the same method and conditions as in the first embodiment. Can do.

In the present invention, the polymer layer 12 is first formed on the intermediate transfer medium 10. Since the polymer layer 12 has a higher surface energy than the intermediate transfer medium 10, even when ink is ejected onto the polymer layer 12, the ink is not repelled and image shrinkage can be suppressed. Next, by applying an aggregating treatment liquid, dots composed of ink aggregates (coloring material aggregates) 18 are formed at the point where ink is deposited.
[Inkjet image forming apparatus]
Next, the inkjet image forming apparatus according to the present invention will be described. FIG. 3 is a schematic configuration diagram of the inkjet image forming apparatus according to the first embodiment. The ink jet image forming apparatus 100 shown in FIG. 3 employs a two-liquid aggregation method and a transfer recording method, and uses an ink and an aggregation treatment agent to form an ink image composed of an ink aggregate (color material aggregate) on the intermediate transfer medium 102. And an ink image formed on the intermediate transfer medium 102 is transferred to the final recording medium 104.

  As shown in FIG. 3, the inkjet image forming apparatus 100 according to the present embodiment includes a polymer layer forming unit 105 that forms a polymer layer by applying PAG or the like on the intermediate transfer medium 102, and a liquid state on the polymer layer. On the intermediate transfer medium 102, an aggregating treatment liquid application unit 106 for applying an aggregation processing agent (aggregation processing liquid), a heating and drying unit 108 for heating and drying the aggregation processing liquid applied on the intermediate transfer medium 102, and the intermediate transfer medium 102. A printing unit (ink ejection unit) 110 that ejects droplets of ink of a plurality of colors and a solvent removal unit 112 that removes the liquid solvent (ink and liquid components of the aggregating treatment liquid) on the intermediate transfer medium 102; It is mainly composed of a transfer unit 114 that transfers the ink image formed on the intermediate transfer medium 102 to the final recording medium 104.

  An endless belt is applied to the intermediate transfer medium 102 shown in FIG. 3, and the intermediate transfer medium (endless belt) 102 is wound around a plurality of stretching rollers (seven stretching rollers 120A to 120G are shown in FIG. 3). When the power of a motor (not shown) is transmitted to at least one of the stretching rollers 120A to 120G, the intermediate transfer medium 102 has a counterclockwise direction in FIG. , In the direction indicated by arrow A).

  The intermediate transfer medium (endless belt) 102 has an image forming region (not shown) on which at least a primary image (ink image) is formed on a surface (image forming surface) 102 </ b> A facing the printing unit 110. And non-penetrable so that ink droplets such as rubber cannot penetrate. Further, at least the image forming area of the intermediate transfer medium 102 is configured to form a horizontal surface (flat surface) having a predetermined flatness.

  Note that the amount (thickness) of the aggregating treatment liquid is reduced between the image forming area of the intermediate transfer medium 102 and a medium having a slow permeation speed with respect to the aggregating treatment liquid (from when the aggregating treatment liquid is applied to when it moves directly below the printing unit 110 A medium having a low permeability of 10% or less may be applied. In other words, the amount (thickness) of the aggregation treatment liquid decreases from 1% or less until the intermediate transfer medium 102 is moved to the printing area immediately below the printing unit 110 after the aggregation treatment liquid is applied. It is also possible to apply a medium having non-permeability including a medium and a medium having low permeability in which the reduction amount of the aggregation treatment liquid is 10% or less.

  In FIG. 3, an endless belt is shown as one embodiment of the intermediate transfer medium 102. However, the intermediate transfer medium applied to the present invention may be a drum shape or a flat plate shape.

  Preferred materials used for the surface layer including the image forming surface 102A of the intermediate transfer medium 102 include, for example, a polyimide resin, a silicon resin, a polyurethane resin, a polyester resin, a polystyrene resin, a polyolefin resin, and a polybutadiene resin. And publicly known materials such as polyamide resins, polyvinyl chloride resins, polyethylene resins, and fluorine resins.

  Further, it is preferable that the surface tension of the surface layer of the intermediate transfer medium 102 is 10 mN / m or more and 40 mN / m or less. When the surface tension of the surface layer of the intermediate transfer medium 102 is 40 mN / m or more, the difference in surface tension from the final recording medium 104 onto which the primary image is transferred is eliminated (or extremely small), and the transfer property of the ink aggregate is reduced. Gets worse.

  The polymer layer forming unit 105 is disposed on the most upstream side in the intermediate transfer medium conveyance direction (the direction indicated by the arrow A in FIG. 3), and includes a coating liquid container 105B that stores a coating roller 105A, a PAG, and the like. Is done. The application roller 105A rotates following the intermediate transfer medium 102, or the application roller 105A is driven independently to control the rotation. As described above, the application roller 105 </ b> A rotates to apply the PAG or the like contained in the application liquid container 105 </ b> B to the image forming surface 102 </ b> A of the intermediate transfer medium 102.

  Similarly, the aggregation treatment liquid application unit 106 disposed on the downstream side of the polymer layer forming unit 105 in the conveyance direction of the intermediate transfer medium is configured to include a coating roller 106A and a coating liquid container 106B that stores the aggregation treatment liquid. The The rotation control of the application roller 106A can also be performed by the same method as the control of the application roller 105A.

  In order to control the film thicknesses of the polymer layer and the aggregation treatment layer, it is preferable to control the contact time between the coating rollers 105A and 106A and the intermediate transfer medium 102. When the contact time between the coating rollers 105A and 106A and the intermediate transfer medium 102 is relatively long, the film thicknesses of the polymer layer and the aggregation treatment layer are relatively increased, and the contact time between the coating roller 106A and the intermediate transfer medium 102 is reduced. When relatively short, the film thicknesses of the polymer layer and the aggregation treatment layer are relatively small.

  The application rollers 105A and 106A are preferably made of a porous material or a material with irregularities on the surface, and for example, a gravure roll can be used.

  FIG. 3 illustrates an example in which the application rollers 105A and 106A are used as one aspect of the application form. However, the application form is not limited to this example, and various methods such as application using a blade can be applied. . In addition, it is possible to apply droplets by an inkjet head to apply the aggregation treatment agent. In the case of the ink jet method, the aggregating treatment liquid can be accurately patterned and applied according to the recorded image (image data), and the heating time and heating energy of the heating and drying unit 108 disposed in the subsequent stage can be shortened. It becomes possible.

  The heating and drying unit 108 disposed downstream of the aggregating treatment liquid application unit 106 in the conveyance direction of the intermediate transfer medium includes a heater (not shown) provided on the back surface 102B side of the image forming surface 102A of the intermediate transfer medium 102. Then, the agglomeration treatment liquid on the intermediate transfer medium 102 is dried by blowing hot air heated by a heater from the back surface 102B side to the intermediate transfer medium 102 to which the agglomeration treatment liquid has been applied.

  The heating temperature of the heater disposed in the heating / drying unit 108 is set according to various conditions such as the type of the aggregating treatment liquid, the application amount (thickness) of the aggregating treatment liquid, and the environmental temperature, and the intermediate temperature after passing through the heating / drying unit 108. A solid or semi-solid aggregation layer is formed on the transfer medium 102.

  For example, after applying the aggregation treatment liquid with a film thickness of about 10 μm onto the intermediate transfer medium 102 by the application roller 106A disposed in the aggregation treatment liquid application unit 106, drying with hot air at 70 ° C. is performed by the heater of the heating drying unit 108. As a result, a solid or semi-solid aggregation treatment layer having a thickness of about 4 μm can be formed on the intermediate transfer medium 102.

  In the present embodiment, an aggregation treatment liquid is applied on the polymer layer, and the aggregation treatment liquid on the intermediate transfer medium 102 is dried by heating, so that a solid or semi-solid aggregation treatment layer is formed on the polymer layer. Although the embodiment to be formed is exemplified, the present invention is not limited to this example in carrying out the present invention, and there is also an embodiment in which a solid or semi-solid solution treatment agent is directly applied on the polymer layer.

  Examples of the direct application of the solid or semi-solid solution treatment agent on the polymer layer include known powders such as fluidized immersion, electrostatic fogging, thermal spraying, electrostatic dry spraying, and spraying. Body spraying methods can be used. In addition, the powder is sprayed using a container having an opening provided with an openable / closable lid and capable of storing powder (solid or semi-solid coagulation treatment agent) inside. It is also possible to do. At this time, open the lid only when passing through the transfer body, spray the powder on the transfer body, close the lid when not in use, and control the powder so that it is not sprayed. It is also possible to control it.

  The printing unit 110 disposed on the downstream side in the intermediate transfer medium conveyance direction of the heating and drying unit 108 includes cyan (C), magenta (M), yellow (Y), black (from the upstream side in the intermediate transfer medium conveyance direction. Ink jet heads (hereinafter simply referred to as “heads”) 110C, 110M, 110Y, and 110K corresponding to the respective colors K) are provided in order. Corresponding color inks are ejected from each of the heads 110C, 110M, 110Y, and 110K onto the image forming surface 102A of the intermediate transfer medium 102 and ejected.

  As shown in FIG. 4, each of the heads 110C, 110M, 110Y, and 110K has a length corresponding to the maximum width of the image forming area in the intermediate transfer medium 102, and the entire width of the image forming area is formed on the ink discharge surface thereof. This is a full-line head in which a plurality of nozzles for ink discharge (not shown in FIG. 4, not shown in FIG. 5 with reference numeral 151) are arranged. Each head 110C, 110M, 110Y, 110K is fixedly installed so as to extend in a direction orthogonal to the intermediate transfer medium conveyance direction.

  According to the configuration in which a full line head having a nozzle row that covers the entire width of the image forming area of the intermediate transfer medium 102 is provided for each ink color, the intermediate transfer medium 102 in the transport direction (sub-scanning direction) of the intermediate transfer medium 102. The primary image can be recorded in the image forming area of the intermediate transfer medium 102 only by performing the operation of relatively moving the printing unit 110 once (that is, by one sub-scan). As a result, high-speed printing is possible compared with the case where a serial (shuttle) type head that reciprocates in a direction (main scanning direction; see FIG. 5) orthogonal to the intermediate transfer medium conveyance direction, and print productivity is improved. Can be improved.

  In this example, the minimum droplet ejection volume (ejection volume) of the ink droplets ejected from the nozzles of the heads 110C, 110M, 110Y, and 110K is 2 pl, and the maximum recording density (maximum dot density) is the main scanning direction ( Both the direction perpendicular to the intermediate transfer medium conveyance direction) and the sub-scanning direction (intermediate transfer medium conveyance direction) are 1200 dpi.

  In this example, the configuration of CMYK standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, and special colors are used as necessary. Ink may be added. For example, it is possible to add an ink head that discharges light-colored ink such as light cyan and light magenta, and the arrangement order of the color heads is not particularly limited.

  The ink storage / loading unit 122 includes an ink tank (not shown in FIG. 3 and indicated by reference numeral 160 in FIG. 7) that stores color inks corresponding to the heads 110C, 110M, 110Y, and 110K. Each tank communicates with a corresponding head through a required flow path. In addition, the ink storage / loading unit 122 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. ing.

  The solvent removal unit 112 is disposed on the downstream side of the printing unit 110 in the intermediate transfer medium conveyance direction, and includes a solvent absorption roller 112A. The solvent absorbing roller 112A of this example is provided at a position facing the roller 120B with the intermediate transfer medium 102 interposed therebetween. The solvent absorbing roller 112A is composed of a roller-shaped porous body (absorbing body). In the solvent removing unit 112, the solvent absorbing roller 112A is brought into contact with the liquid solvent (the solvent component of the ink and the aggregating treatment liquid) on the intermediate transfer medium 102, and the liquid solvent is brought into the porous body by the capillary force of the porous body. By absorbing it, the liquid solvent is removed from the intermediate transfer medium 102.

  The solvent absorbing roller 112A may be driven to rotate according to the movement (conveyance) of the intermediate transfer medium 102 or may be rotated independently. Further, it is preferable that the intermediate transfer medium 102 is configured to be separated from the image forming surface 102A.

  The surface energy of the surface of the solvent absorbing roller 112A (the surface that contacts the image forming surface 102A of the intermediate transfer medium 102) is preferably smaller than the surface energy of the image forming surface 102A of the intermediate transfer medium 102. A member having a surface energy of 30 mN / m or less is applied to the roller 112A.

  By removing the solvent using the solvent absorbing roller 112A that satisfies the surface energy condition described above, the liquid solvent on the intermediate transfer medium 102 can be absorbed and removed while preventing the coloring material from adhering to the solvent absorbing roller 112A. It becomes possible.

  Instead of the solvent absorbing roller 112A, a method of removing excess solvent from the intermediate transfer medium 102 with an air knife, a method of evaporating and removing the solvent by blowing dry air, or the like may be applied.

  As a method for removing the solvent, it is more preferable to use a method that does not depend on heating. In the method of heating the surface of the intermediate transfer medium 102 or the method of applying heat to the ink aggregate on the intermediate transfer medium 102 to evaporate the solvent, the solvent is excessively removed by overheating of the ink aggregate, and the transfer is performed. In some cases, the preferred viscoelasticity of the aggregate cannot be maintained, and the transfer property to the final recording medium 104 may be deteriorated. In addition, the polymer layer may flow due to heating, and sufficient adhesion with the intermediate transfer medium cannot be maintained, and a desired image may not be maintained from the solvent removal step to the transfer step.

  On the other hand, in the mode in which the solvent on the image forming surface 102A of the intermediate transfer medium 102 is absorbed and removed by the solvent absorbing roller 112A, even when a large amount of solvent remains on the intermediate transfer medium 102, it takes less time than other methods. Since a large amount of solvent can be removed, a large amount of solvent (dispersion medium) is not transferred to the final recording medium 104 by the transfer unit 114 at the subsequent stage. Therefore, even when paper is used as the final recording medium 104, it is possible to form an image without causing problems characteristic to aqueous solvents such as curls and cockles.

  Further, by removing excess solvent from the ink aggregate using the solvent removal unit 112, the ink aggregate can be concentrated and the internal aggregating force can be further increased. Thereby, a stronger internal cohesion force can be applied to the ink aggregate until the transfer process by the transfer unit 114. Further, the effective concentration of the ink aggregates by removing the solvent can impart good fixability and gloss to the image even after the image is transferred to the final recording medium 104.

  Note that it is not always necessary to remove all the solvent on the intermediate transfer medium 102 by the solvent removing unit 112. If the ink aggregate is excessively removed by excessively removing it, the adhesion force of the ink aggregate to the intermediate transfer medium 102 becomes too strong, and an excessive pressure is required for transfer, which is not preferable. Rather, in order to maintain viscoelasticity suitable for transferability, it is preferable to leave a small amount.

  The effects obtained by leaving a small amount of the solvent on the intermediate transfer medium 102 include the following. That is, since ink aggregates are hydrophobic and solvent components that are difficult to volatilize (mainly organic solvents such as glycerin) are hydrophilic, ink aggregates and residual solvent components are separated after solvent removal, and residual solvent components A thin liquid layer is formed between the ink aggregate and the intermediate transfer medium. Therefore, the adhesion force of the ink aggregate to the intermediate transfer medium 102 becomes weak, which is advantageous for improving transferability.

  The solvent removal control described above can be performed by changing the pressure applied to the intermediate transfer medium 102 by the solvent absorbing roller 112A. When the solvent removal amount is relatively increased, the pressure on the intermediate transfer medium 102 of the solvent absorption roller 112A is increased, and when the solvent removal amount is relatively decreased, the intermediate transfer medium of the solvent absorption roller 112A. What is necessary is just to make the press to 102 small.

  In addition, a mode in which a plurality of solvent absorption rollers having different absorption characteristics are provided and the solvent absorption roller to be used is selectively switched according to the amount of solvent removal is also possible.

  In the inkjet image forming apparatus 100 shown in FIG. 3, a preheating unit 124 is provided between the solvent removal unit 112 and the transfer unit 114. The preheating unit 124 includes a heater (not shown) provided on the back surface 102B side of the image forming surface 102A of the intermediate transfer medium 102, and the intermediate transfer medium 102 on which the primary image (ink image) is formed. It is configured to preheat with a heater from the back surface 102B side. A flat plate heater is suitably used for the preheating unit 124 in this example. Further, in this example, the configuration in which the heater is disposed outside the intermediate transfer medium 102 is shown, but a mode in which the heater is built in the intermediate transfer medium 102 is also possible.

  The heating temperature range of the heater disposed in the preheating unit 124 is 30 to 100 ° C., and is set lower than the heating temperature at the time of transfer. By preheating the image forming area of the intermediate transfer medium 102, the heating temperature of the transfer unit 114 can be set lower than when no preheating is performed, and the transfer time of the transfer unit 114 is further reduced. be able to.

  In the preheating unit 124, heating is performed so that the temperature of the image forming surface 102A of the intermediate transfer medium 102 (the temperature of the region where the image is formed) exceeds the glass transition temperature Tg of the polymer fine particles contained in the ink. The temperature is preferably set. In this example, the heating temperature is set to 120 ° C.

  The transfer unit 114 disposed on the downstream side of the preheating unit 124 in the conveyance direction of the intermediate transfer medium includes a transfer heating roller 114A having a heater (not shown), and heating for a heating and pressure nip disposed opposite thereto. The intermediate transfer medium 102 and the final recording medium 104 are sandwiched between these rollers 114A and 114B and heated at a predetermined temperature and pressurized at a predetermined pressure (nip pressure). The primary image formed on the intermediate transfer medium 102 is transferred to the final recording medium 104.

  The heating temperature (transfer temperature) by the transfer unit 114 is preferably a temperature at which the polymer layer dissolves, specifically 50 ° C to 200 ° C is preferable, and 50 ° C to 200 ° C is also preferable from the viewpoint of transferability. When the heating temperature by the transfer unit 114 exceeds the above range, there is a problem such as deformation of the intermediate transfer medium 102. On the other hand, if it is lower than the above range, there is a problem that transferability deteriorates.

  The nip pressure by the transfer unit 114 is preferably 0.5 to 10 MPa. As a means for adjusting the nip pressure at the time of transfer in the transfer unit 114, for example, a mechanism (drive means) for moving the transfer heating roller 114A in the vertical direction (shown by reference C) in FIG. That is, when the transfer heating roller 114A is moved away from the heating counter roller 114B, the nip pressure decreases, and when it is moved closer to the heating counter roller 114B, the nip pressure increases.

  As a configuration of the paper feeding unit 126 that supplies the final recording medium 104 to the transfer unit 114, an embodiment including a roll paper (continuous paper) magazine, or in place of or in combination with a roll paper magazine, cutting is performed. There is a mode in which paper is supplied by a cassette in which paper is stacked and loaded. In the case of an apparatus configuration using roll paper, a cutter for cutting is provided, and the roll paper is cut into a desired size by the cutter. A plurality of magazines and cassettes having different paper widths and paper qualities may be provided.

  When a plurality of types of final recording media can be used, an information recording body such as a bar code or a wireless tag that records the media type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Thus, it is preferable to automatically determine the type (media type) of the final recording medium to be used and perform ink ejection control so as to realize appropriate ink ejection according to the media type.

  Specific examples of the final recording medium 104 applied to this example include permeable media such as plain paper and inkjet paper, non-permeable or low permeable media such as coated paper, and an adhesive and a release label on the back surface. There are various media such as sticker paper, resin films such as OHP sheets, metal sheets, cloth, and wood.

  A mode in which the cooling unit 128 is disposed downstream of the transfer unit 114 in the intermediate transfer medium conveyance direction is preferable. The cooling unit 128 cools the intermediate transfer medium 102 and the final recording medium 104 that have passed through the transfer unit 114 and bonded together. The cooling unit 128 is preferably applied with a mode in which cool air is blown by a cooling fan or the like, and the cooling temperature or the like can be adjusted. The cooling unit 128 shown in this example has a configuration in which a moving time (cooling time) of the intermediate transfer medium 102 for cooling to a desired temperature is secured. By separating the intermediate transfer medium 102 and the final recording medium 104 after cooling, a transfer failure due to temperature unevenness or the like can be prevented, and stable image transfer (peeling) becomes possible.

  A peeling unit 130 is disposed downstream of the cooling unit 128 in the conveyance direction of the intermediate transfer medium. The peeling unit 130 is configured to peel the final recording medium 104 from the intermediate transfer medium 102 with the rigidity (waist strength) of the final recording medium 104 itself by the winding curvature of the peeling roller 120E of the intermediate transfer medium 102. . The peeling part 130 may be used in combination with means for promoting peeling such as a peeling nail.

  A fixing unit 132 is disposed downstream of the peeling unit 130 in the final recording medium conveyance direction (the direction indicated by arrow B in FIG. 3). The fixing unit 132 includes a heating roller pair 132A whose temperature can be adjusted in a range of 50 ° C. to 200 ° C., and performs final recording while heating and pressurizing the final recording medium 104 sandwiched between the heating roller pair 132A. The image transferred to the medium 104 is fixed.

  The heating temperature of the fixing unit 132 is preferably set according to the glass transition temperature of the polymer fine particles contained in the ink. In this example, the heating temperature of the fixing unit 132 is set to 130 ° C. Further, it is preferable that the nip pressure of the fixing unit 132 is 0.5 to 10 MPa. Note that if the transfer unit 114 can achieve both image transfer and fixing, a mode in which the fixing unit 132 is omitted is also possible.

  A cleaning unit 134 is disposed downstream of the peeling unit 130 in the conveyance direction of the intermediate transfer medium. The cleaning unit 134 serves as a means for cleaning the intermediate transfer medium 102 after image transfer to the final recording medium 104, and removes post-transfer residues (ink aggregates and the like) while contacting the image forming surface 102A of the intermediate transfer medium 102. It comprises a blade (not shown) for wiping and removing, and a collection unit (not shown) for collecting the removed post-transfer residue.

  The structure of the cleaning means for removing the post-transfer residue from the intermediate transfer medium 102 is not limited to the above example, but a system that nips a brush roll, a water absorbing roll, etc., an air blow system that blows clean air, an adhesive roll There are methods or combinations thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  Next, the structure of the heads 110C, 110M, 110Y, and 110K arranged in the printing unit 110 will be described in detail. Since the heads 110C, 110M, 110Y, and 110K have the same structure, the head is denoted by reference numeral 150 as a representative of them.

  5A is a perspective plan view showing an example of the structure of the head 150, FIG. 5B is an enlarged view of a part thereof, and FIG. 5C is a plan view showing another example of the structure of the head 150. FIG. FIG. 6 is a cross-sectional view (a cross-sectional view taken along line 8-8 in FIGS. 5A and 5B) showing a three-dimensional configuration of the ink chamber unit.

  In order to increase the dot pitch formed on the intermediate transfer medium 102, it is necessary to increase the nozzle pitch in the head 150. As shown in FIGS. 5A and 5B, the head 150 of this example includes a plurality of ink chamber units 153 including nozzles 151 serving as ink droplet ejection holes, pressure chambers 152 corresponding to the nozzles 151, and the like. Are arranged in a staggered matrix (two-dimensionally), so that the projection is substantially performed so as to be aligned along the longitudinal direction of the head (main scanning direction orthogonal to the intermediate transfer medium conveyance direction). High nozzle density (projection nozzle pitch) is achieved.

  The form in which one or more nozzle rows are formed over a length corresponding to the entire width of the intermediate transfer medium 102 in a direction substantially orthogonal to the conveyance direction of the intermediate transfer medium 102 is not limited to this example. For example, instead of the configuration of FIG. 5A, as shown in FIG. 5C, short head blocks 150 ′ in which a plurality of nozzles 151 are two-dimensionally arranged are arranged in a staggered manner and joined together. A line head having a nozzle row having a length corresponding to the entire width of the intermediate transfer medium 102 may be configured. Although not shown, a line head may be configured by arranging short heads in a line.

  The pressure chamber 152 provided corresponding to each nozzle 151 has a substantially square planar shape, and nozzles 151 and supply ports 154 are provided at both corners on a diagonal line. Each pressure chamber 152 communicates with a common flow path 155 through a supply port 154. The common flow path 155 communicates with an ink supply tank (not shown in FIG. 6; indicated by reference numeral 160 in FIG. 7) as an ink supply source, and the ink supplied from the ink supply tank passes through the common flow path 155. Distribution is supplied to each pressure chamber 152.

  A piezoelectric element 158 having an individual electrode 157 is joined to a diaphragm 156 that constitutes the top surface of the pressure chamber 152 and also serves as a common electrode. By applying a drive voltage to the individual electrode 157, the piezoelectric element 158 Deformation causes ink to be ejected from the nozzle 151. When ink is ejected, new ink is supplied from the common channel 155 through the supply port 154 to the pressure chamber 152.

  In this example, the piezoelectric element 158 is applied as a means for generating ink ejection force to be ejected from the nozzles 151 provided in the head 150. However, a heater is provided in the pressure chamber 152 and the pressure of film boiling caused by heating of the heater is used. It is also possible to apply a thermal method that ejects ink.

  As shown in FIG. 5B, the ink chamber units 153 having such a structure are arranged in a fixed manner along a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. By arranging a large number of patterns in a lattice pattern, the high-density nozzle head of this example is realized.

  That is, with a structure in which a plurality of ink chamber units 153 are arranged at a constant pitch d along the direction of an angle θ with respect to the main scanning direction, the pitch P of the nozzles projected in the main scanning direction is d × cos θ. Thus, in the main scanning direction, each nozzle 151 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction.

  In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example, and various nozzle arrangement structures such as an arrangement structure having one nozzle row in the sub-scanning direction can be applied.

  Further, the application range of the present invention is not limited to the printing method using the line type head, and a short head that does not reach the length in the width direction (main scanning direction) of the intermediate transfer medium 102 is scanned in the width direction of the intermediate transfer medium 102. Then, printing in the width direction is performed, and when printing in one width direction is completed, the intermediate transfer medium 102 is moved by a predetermined amount in a direction (sub-scanning direction) perpendicular to the width direction, and the middle of the next printing area A serial method may be applied in which printing in the width direction of the transfer medium 102 is performed and printing is performed over the entire printing area of the intermediate transfer medium 102 by repeating this operation.

  FIG. 7 is a schematic diagram illustrating a configuration of an ink supply system in the inkjet image forming apparatus 100. As shown in FIG. 7, the ink supply tank 160 is a base tank that supplies ink to the head 150, and is included in the ink storage / loading unit 122 described with reference to FIG. The ink supply tank 160 includes a system that replenishes ink from a replenishment port (not shown) and a cartridge system that replaces the entire tank when the remaining amount of ink is low. A cartridge system is suitable for changing the ink type according to the intended use. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type.

  As shown in FIG. 7, a filter 162 is provided between the ink supply tank 160 and the head 150 in order to remove foreign substances and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter (generally about 20 μm).

  Although not shown in FIG. 7, a configuration in which a sub tank is provided in the vicinity of the head 150 or integrally with the head 150 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the inkjet image forming apparatus 100 is provided with a cap 164 as a means for preventing the nozzle 151 from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 166 as a means for cleaning the ink ejection surface of the head 150. ing.

  The maintenance unit including the cap 164 and the cleaning blade 166 can be moved relative to the head 150 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the head 150 as necessary.

  The cap 164 is displaced up and down relatively with respect to the head 150 by an elevator mechanism (not shown). The cap 164 is raised to a predetermined raised position when the power is turned off or during printing standby, and is brought into close contact with the head 150, thereby covering the nozzle surface with the cap 164.

  During printing or standby, if the frequency of use of a specific nozzle 151 is reduced and ink is not ejected for a certain period of time, the ink solvent near the nozzle evaporates and the ink viscosity increases. In such a state, ink cannot be ejected from the nozzle 151 even if the piezoelectric element 158 operates.

  Before such a state is reached (within the range of viscosity that can be discharged by the operation of the piezoelectric element 158), the piezoelectric element 158 is operated, and a cap is formed to discharge the deteriorated ink (ink near the nozzle whose viscosity has increased). Preliminary ejection (purging, idle ejection, collar ejection, dummy ejection) is performed toward 164 (ink receiving).

  A mode in which preliminary ejection is performed by ejecting ink toward the intermediate transfer medium 102 is also possible. For example, when a plurality of images are continuously formed, preliminary ejection can be performed between images. In particular, when a plurality of the same images are formed, the frequency of ink ejection at a specific nozzle is reduced, and the possibility of occurrence of ejection abnormality is increased, so that preliminary ejection can be performed between images for the specific nozzle. preferable.

  When preliminary discharge is performed on the intermediate transfer medium 102, the solvent absorption roller 112A and the transfer heating roller 114A are moved to prevent the ink from the preliminary discharge from adhering to the solvent absorption roller 112A and the transfer heating roller 114A. A predetermined clearance (for example, about 10 mm) may be provided between 112A and the transfer heating roller 114A and the intermediate transfer medium 102.

  Further, when air bubbles are mixed into the ink in the head 150 (in the pressure chamber 152), the ink cannot be ejected from the nozzle even if the piezoelectric element 158 operates. In such a case, the cap 164 is applied to the head 150, the ink in the pressure chamber 152 (ink mixed with bubbles) is removed by suction with the suction pump 167, and the suctioned and removed ink is sent to the recovery tank 168.

  In this suction operation, the deteriorated ink with increased viscosity (solidified) is sucked out when the ink is initially loaded into the head or when the ink is used after being stopped for a long time. Since the suction operation is performed on the entire ink in the pressure chamber 152, the amount of ink consumption increases. Therefore, it is preferable to perform preliminary ejection when the increase in ink viscosity is small.

  The cleaning blade 166 is made of an elastic member such as rubber, and can slide on the ink ejection surface of the head 150 by a blade moving mechanism (not shown). When ink droplets or foreign matter adhere to the ink ejection surface, the ink ejection surface is wiped by sliding the cleaning blade 166 on the ink ejection surface, and the ink ejection surface is cleaned.

  Next, the operation of the above-described inkjet image forming apparatus 100 will be described.

  In FIG. 3, while the intermediate transfer medium 102 is conveyed in the intermediate transfer medium conveyance direction (the direction indicated by arrow A in FIG. 3), first, the PAG or the like is transferred to the intermediate transfer medium 102 by the application roller 105A of the polymer layer forming unit 105. The polymer layer is applied to form a polymer layer (polymer layer forming step). Next, the aggregation treatment liquid is applied onto the polymer layer by the application roller 106A of the aggregation treatment liquid application unit 106 (aggregation treatment liquid application step). Subsequently, the heat drying unit 108 heats and drys the aggregation treatment liquid on the intermediate transfer medium 102 to form a solid or semi-solid aggregation treatment layer on the intermediate transfer medium 102 (aggregation treatment liquid drying step). ). As described above, a solid or semi-solid aggregation treatment agent may be directly applied onto the intermediate transfer medium 102, and in this case, the aggregation treatment liquid drying step can be omitted.

  Next, ink droplets of each color are ejected by the heads 110C, 110M, 110Y, and 110K of the printing unit 110 (ink ejection process). When the ink droplets land on the solid or semi-solid aggregation processing layer formed on the intermediate transfer medium 102, the aggregation reaction is instantly started from the contact surface with the aggregation processing layer, and a predetermined value is formed on the aggregation processing layer. Ink aggregates (coloring material aggregates) having a size of 1 are formed. After the ink aggregates are formed, the solid or semi-solid aggregation process layer formed on the polymer layer is dissolved by the action of the ink solvent separated from the ink aggregates. The ink aggregate that has spread further can obtain a sufficient adhesion force with the polymer layer. In addition, since sufficient adhesive force can be obtained between the polymer layer and the intermediate transfer medium 102, it is possible to prevent the color material from moving on the intermediate transfer medium 102.

  Next, the liquid solvent (the ink and the solvent component of the aggregation treatment liquid) on the intermediate transfer medium 102 is absorbed and removed by the solvent absorbing roller 112A of the solvent removing unit 112. As described above, since the dots made of the ink aggregate (color material aggregate) can obtain a sufficient adhesion force with the intermediate transfer medium 102, the color material adhesion to the solvent absorbing roller 112A can be prevented. it can.

  As described above, after the ink image formed of the ink aggregate is formed on the intermediate transfer medium 102 while preventing the movement of the color material and the color material, the preheating unit 124 causes the ink image on the intermediate transfer medium 102 to be a predetermined amount. The ink image heated on the temperature (preliminary heating step) and formed on the intermediate transfer medium 102 by the transfer unit 114 is transferred to the final recording medium 104 (transfer step).

  After the transfer process is performed, the final recording medium 104 peeled from the intermediate transfer medium 102 by the peeling unit 130 is heated and pressed while being sandwiched by the pair of heating rollers 132A of the fixing unit 132. Fixing is performed (fixing process).

  In the present embodiment, as described above, the cooling unit 128 is preferably provided between the transfer unit 114 and the peeling unit 130. The peelability of the final recording medium 104 can be improved.

  The intermediate transfer medium 102 from which the final recording medium 104 has been peeled off from the peeling unit 130 is subjected to removal of post-transfer residue in a cleaning unit 134 (cleaning process). Thereafter, the above-described steps are sequentially repeated.

  Next, another embodiment (second embodiment) of the inkjet image forming apparatus according to the present invention will be described. FIG. 8 is a schematic configuration diagram of an inkjet image forming apparatus according to the second embodiment.

  In the inkjet image forming apparatus 200 shown in the second embodiment, the aggregation treatment liquid application unit 106 is arranged on the downstream side of the printing unit (ink droplet ejection unit) 110 in the intermediate transfer medium conveyance direction, and the heat drying unit 108 is not provided. This is different from the first embodiment. In addition, about each structure of the inkjet image forming apparatus 200, the thing of the structure and conditions similar to the inkjet image forming apparatus 200 shown in 1st Embodiment can be used.

  The operation of the inkjet image forming apparatus 200 according to the second embodiment will be described. In FIG. 8, while the intermediate transfer medium 102 is conveyed in the intermediate transfer medium conveyance direction (the direction indicated by the arrow A in FIG. 8), first, the PAG or the like is transferred to the intermediate transfer medium 102 by the application roller 105A of the polymer layer forming unit 105. The polymer layer is applied to form a polymer layer (polymer layer forming step). Next, ink droplets of each color are ejected by the heads 110C, 110M, 110Y, and 110K of the printing unit 110 (ink ejection process). Since the polymer layer has a higher surface energy than the intermediate transfer medium 102, the ink droplets are fixed on the polymer layer.

  Next, the aggregating treatment liquid applying unit 106 applies the aggregating treatment liquid onto the ink droplets deposited (coagulation treatment liquid applying step). When the aggregating treatment liquid comes into contact with the ink, the aggregating reaction starts instantaneously from the contact point of the ink with the aggregating treatment liquid. On the polymer layer, an ink aggregate (coloring material aggregate) spreading to a predetermined size is formed. After the ink aggregate is formed, the industry treatment agent is dissolved by the action of the ink solvent separated from the ink aggregate, but the ink aggregate can obtain sufficient adhesion between the polymer aggregate. Further, image shrinkage can be suppressed, and color material movement on the intermediate transfer medium 102 can be prevented.

  Next, the solvent absorption roller 112A of the solvent removal unit 112 absorbs and removes the liquid solvent (the solvent component of the ink and the aggregation processing liquid) on the intermediate transfer medium 102. The subsequent steps are the same as in the first embodiment. Since this is the process, the description is omitted.

  As described above, in the present invention, even if the order of the step of applying the aggregating treatment liquid and the step of depositing the ink is reversed, the fixing property of the ink to the intermediate transfer medium and the releasability at the time of transfer are maintained and good. An image can be formed.

  Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

<Image shrinkage and transfer image evaluation experiment>
[Test Example 1: Formation of polymer layer → coagulation treatment liquid application → drying → ink ejection]
Using the inkjet image forming apparatus shown in FIG. 3, an image was recorded on an intermediate transfer medium, and then transferred to plain paper to form a main image.

  First, a material for forming the polymer layer shown in FIG. 9 was applied to the intermediate transfer belt (SIFEL: manufactured by Shin-Etsu Chemical Co., Ltd.) that passed through the cleaning process, to form a polymer layer having a thickness of 1 μm. Next, the aggregation treatment agent shown below was uniformly applied to a film thickness of about 10 μm and dried by hot air drying at 70 ° C. to form a solid or semi-solid aggregation treatment layer on the intermediate transfer belt.

  Next, ink was ejected from the ink head according to the image signal to perform droplet ejection. The ink ejection volume was 2 pl, and the recording density was 1200 dpi in both the main scanning and sub-scanning directions. Then, in a state where the ink was separated into the pigment aggregate and the solvent by the aggregation reaction, the solvent was absorbed and removed using a solvent absorbing roller made of a porous material.

Next, the intermediate transfer belt was heated to 90 ° C. by a flat plate heater, and then transferred from the intermediate transfer belt to plain paper with a transfer roller at a nip pressure of 2 MPa. The section from the transfer roller to the peeling portion was cooled to 70 ° C. by a cooling member, and finally, the plain paper was fixed by applying pressure and heating at 120 ° C. and 2 MPa to form an image on the plain paper. The image shrinkage on the intermediate transfer medium, the color material adhesion to the solvent absorption roller, and the transfer rate to plain paper were measured and evaluated. In addition, as a comparative example, evaluation was also performed on an image formed without forming a polymer layer.
≪Adjustment of coagulation treatment agent≫
The materials were mixed and adjusted with the following composition.
・ Diethylene glycol 20g
・ Orphine E1010 (manufactured by Nissin Chemical Industry) 1g
・ 2-Pyrrolidone-5-carboxylic acid 1g
・ Sodium hydroxide 0.25g
・ Ion exchange water 77.8g
After mixing, when the pH of the treatment liquid was measured with a pH meter WM-50EG (manufactured by Toa DKK), the pH was 3.5.
≪Ink adjustment≫
・ Cromophtal Jet Magenta DMQ (PR-122) (Ciba Specialty Chemicals)
10g
・ Low molecular weight dispersant 2-1 (shown in (1)) 10 g
・ Glycerin 4g
・ Ion-exchanged water 26g

  The above materials were mixed with stirring to prepare a dispersion. Next, using an ultrasonic irradiation device (Vibra-cell VC-750, taper microchip: φ 5 mm, Amplitude: 30%) (manufactured by SONICS), ultrasonic waves are intermittently irradiated to the dispersion (irradiation 0.5 s / pause) 1.0 s) for 2 hours to further disperse the pigment, thereby preparing a 20% by mass pigment dispersion.

Separately from the 20% by mass pigment dispersion, the following compounds were weighed and mixed with stirring to prepare a mixture I.
・ Glycerin 5g
・ Diethylene glycol 10g
・ Orphine E1010 (manufactured by Nissin Chemical Industry) 1g
・ Ion exchange water 11g
This mixture I. The mixture was slowly dropped into 23.0 g of a stirred 44% SBR dispersion (polymer fine particles: 3% by mass of acrylic acid, Tg: 30 ° C.), and mixed by stirring to prepare a mixed solution II. This mixed solution II was stirred and mixed while slowly dropping into the above-mentioned 20% pigment dispersion to prepare 100 g of magenta ink.

The results are shown in FIG. The evaluation in the table was performed according to the following criteria.
[Image shrinkage]
○ ・ ・ ・ Image shrinkage 1% or less △ ・ ・ ・ Image shrinkage 5% or less × ・ ・ ・ Image shrinkage 5% or more [Color material adhesion]
○ ... No color material adhesion △ ... Color material adhesion slightly present (5% or less in terms of ink amount)
× ・ ・ ・ Color material adhering (5% or more in terms of ink amount)
[Transfer rate]
○ ... Transfer rate 95% or more Δ ... Transfer rate 90% or more × ... Transfer rate less than 90% As shown in FIG. Although the material adhesion and the transfer rate were poor, good results were obtained in Examples 1 to 10 in which the polymer layer was formed. Particularly good results were obtained by using a WAX-like material at room temperature as a material for forming the polymer layer.
[Test Example 2: Formation of polymer layer → coagulation treatment liquid application → ink ejection]
An image was formed by the same method as in Test Example 1 except that the aggregation treatment liquid was not applied. The results are shown in FIG.

Compared with the case where drying was performed after applying the aggregating treatment liquid, the color material adhesion to the solvent absorbing roller and the transfer rate were inferior, but at a satisfactory level.
[Test Example 3: Formation of polymer layer → ink ejection → coagulation treatment liquid application]
An image was formed by the same method as in Test Example 2 except that the order of the aggregation treatment liquid application step and the ink droplet ejection step was changed. The results are shown in FIG.

  Similar to Test Example 2, although the color material adhesion and transfer rate were inferior, there were no problems.

It is the model which showed an example of the inkjet image forming method which concerns on this invention. It is the model which showed another aspect of the inkjet image forming method which concerns on this invention. 1 is a schematic diagram illustrating an example of an inkjet image forming apparatus according to the present invention. FIG. 4 is a plan view of a main part around a printing unit of the inkjet image forming apparatus shown in FIG. 3. FIG. 3 is a plan perspective view illustrating a configuration example of an ink head. It is sectional drawing which follows the 8-8 line in FIG. It is the schematic which shows the structure of the ink supply system of the inkjet image forming apparatus shown in FIG. It is the model which showed another aspect of the inkjet image forming apparatus which concerns on this invention. 6 is a table showing the results of Test Example 1. FIG. 10 is a table showing the results of Test Example 2. FIG. 10 is a table showing the results of Test Example 3. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 102 ... Intermediate transfer medium, 12 ... Polymer layer, 14 ... Aggregation treatment layer, 16 ... Ink droplet, 18 ... Ink aggregate (coloring material aggregate), 20, 112A ... Solvent absorption roller, 22, 104 ... Final recording medium, 24 ... dissolved PAG, etc., 26 ... aggregation treatment agent, 100 ... inkjet image forming apparatus, 105 ... polymer layer formation unit, 106 ... aggregation treatment liquid application unit, 108 ... heat drying unit, 110 ... printing unit (Ink droplet ejection part), 112 ... Solvent removal part, 114 ... Transfer part, 114A ... Transfer heating roller, 122 ... Ink storage / loading part, 124 ... Preheating part, 128 ... Cooling part, 130 ... Peeling part, 132 ... Fixing unit, 134 ... cleaning unit, 150 ... head, 151 ... nozzle, 152 ... pressure quality, 153 ... ink chamber unit, 154 ... supply port, 155 ... supply flow dew, 156 ... vibration plate, 157 Individual electrodes, 158 ... piezoelectric element, 160 ... ink supply tank, 162 ... filter, 164 ... Cap, 166 ... cleaning blade 167 ... suction pump, 168 ... recovery tank

Claims (10)

On the intermediate transfer medium, a polyalkylene glycol, a polyalkylene glycol ester or a polyoxyalkylene glycol ester is applied as a material for forming the polymer layer, and a polymer layer forming step for forming the polymer layer;
An aggregating treatment liquid application step of applying a liquid aggregating treatment liquid for aggregating the ink on the polymer layer;
An ink droplet deposition step of depositing ink according to an image signal on the aggregation treatment liquid to form an ink aggregate;
An ink solvent removing step for removing the solvent in the ink aggregate;
A transfer step in which the ink aggregate formed on the intermediate transfer medium is subjected to thermal pressure transfer onto a recording medium.   The inkjet image forming method according to claim 1, further comprising an aggregation treatment liquid drying step of drying the aggregation treatment liquid after the aggregation treatment liquid application step. On the intermediate transfer medium, a polyalkylene glycol, a polyalkylene glycol ester or a polyoxyalkylene glycol ester is applied as a material for forming the polymer layer, and a polymer layer forming step for forming the polymer layer;
An ink ejection step of ejecting ink according to an image signal on the polymer layer;
An aggregating treatment liquid coating step for forming an ink aggregate by applying a liquid aggregating treatment liquid for aggregating the ink on the ink;
An ink solvent removing step for removing the solvent in the ink aggregate;
A transfer step in which the ink aggregate formed on the intermediate transfer medium is subjected to thermal pressure transfer onto a recording medium.   The inkjet image forming method according to any one of claims 1 to 3, wherein the polyalkylene glycol, polyalkylene glycol ester, and polyoxyalkylene glycol ester are in the form of wax.   The inkjet image forming method according to any one of claims 1 to 4, wherein the material forming the polymer layer is a polyalkylene glycol ester or a polyalkylene glycol ether.   6. The ink jet image forming method according to claim 1, wherein the surface energy of the polymer layer at room temperature is 25 mN / m or more.   The ink jet image forming method according to claim 1, wherein the ink is ejected onto the polymer layer having a melting temperature or lower. A polymer layer forming means for applying a polyalkylene glycol, a polyalkylene glycol ester or a polyoxyalkylene glycol ester as a material for forming a polymer layer on an intermediate transfer medium, and forming a polymer layer;
An aggregating treatment liquid applying means for applying a liquid aggregating treatment liquid for aggregating the ink on the polymer layer;
An ink droplet ejecting means for depositing ink according to an image signal on the aggregation treatment liquid to form an ink aggregate;
An ink solvent removing means for removing the solvent in the ink aggregate;
An ink jet image forming apparatus comprising: a transfer unit that performs hot-pressure transfer of the ink aggregate formed on the intermediate transfer medium to a recording medium.   The inkjet image forming apparatus according to claim 8, further comprising an aggregating treatment liquid drying unit that dries the aggregating treatment liquid after the aggregating treatment liquid applying unit. A polymer layer forming means for applying a polyalkylene glycol, a polyalkylene glycol ester or a polyoxyalkylene glycol ester as a material for forming a polymer layer on an intermediate transfer medium, and forming a polymer layer;
Ink droplet ejection means for ejecting ink in accordance with an image signal on the polymer layer;
An aggregating treatment liquid coating unit that forms an ink aggregate by applying a liquid aggregating treatment liquid for aggregating the ink on the ink;
An ink solvent removing means for removing the solvent in the ink aggregate;
An ink jet image forming apparatus comprising: a transfer unit that performs hot-pressure transfer of the ink aggregate formed on the intermediate transfer medium to a recording medium.

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