JP2018149724A - Image recording method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image recording method and apparatus capable of obtaining an image excellent in gloss uniformity and durability using a contact type coating method which is inexpensive compared to a non-contact type coating method.SOLUTION: There is provided an image recording method which comprises: an image recording step of recording an image on a base material to which an image quality improving agent is imparted; and a gloss imparting agent coating step of coating a gloss imparting agent by a contact type coating method on an image surface of the base material on which an image is recorded by the image recording step, wherein the gloss imparting agent is a material which is changed in performance by reacting with the image quality improving agent and the gloss imparting agent coating step imparts the gloss imparting agent on the image surface using a slab member having a rugged structure in which an uneven pattern is made different according to the image density of teh image.SELECTED DRAWING: Figure 20

Description

  The present invention relates to an image recording method and apparatus, and more particularly to an image forming technique using an image quality improver and a gloss imparting agent that improve the image quality of an image recorded using ink.

  The ink jet printing method, which is a non-contact printing method, uses an ink having a lower viscosity than the contact printing method using a conventional plate. For this reason, a phenomenon called landing interference in which ink droplets ejected onto a substrate by ink jet printing contact each other and move irregularly, and a period until ink droplets ejected dry Image quality degradation such as the appearance of graininess. In order to solve these problems, a method has been developed in which an undercoat liquid that suppresses the spread and movement of ink on a substrate is applied to the substrate before printing.

  On the other hand, in the printing field, a method of applying an overcoating liquid such as varnish or transparent ink to the image surface after image recording is known in order to give gloss to the surface of the printed matter. In Patent Document 1, an image is recorded by an ink jet printing method, and transparent ink is ejected onto the recorded image to give gloss to the image area. The method described in Patent Document 1 discloses a configuration in which the amount of transparent ink applied is adjusted depending on the area of the image, from the viewpoint of achieving a uniform glossiness in the entire image.

Japanese Patent Laying-Open No. 2015-9554

  [Problem 1] When a varnish for applying gloss is applied to an image recorded by a method using an undercoat liquid, there arises a problem of non-uniform gloss, in which the gloss varies depending on the image density of the recorded image. Specifically, there is a phenomenon in which the gloss in the non-image portion, particularly in the halftone portion, is reduced with respect to the solid portion. The cause of this is considered to be that the components contained in the varnish react with the components of the undercoat liquid to change the performance of the varnish. For example, in the non-image area and halftone area, the undercoat liquid component present on the substrate reacts with the polymer component in the varnish to aggregate the polymer component and level the surface of the varnish layer. It is thought to inhibit. On the other hand, in the solid portion, since the active component of the undercoat liquid is consumed by the ink applied on the base material, such agglomeration of the polymer component hardly occurs.

  Such a problem 1 is a new technical problem peculiar to the case of using a varnish having a characteristic that the performance is changed by reacting with a component of the undercoat liquid. Problem 1 is also the same for the case of using a base material to which an image quality improving agent corresponding to the undercoat liquid has been previously applied.

  The method described in Patent Document 1 does not use an undercoat liquid. Furthermore, the method described in Patent Document 1 has the following problems.

  [Problem 2] In the method described in Patent Document 1, since the application amount of the transparent ink varies depending on the location on the image surface, the durability of the image portion at a portion where the application amount is small is lowered.

  [Problem 3] The method described in Patent Document 1 uses an inkjet head as means for applying transparent ink to the image surface. The inkjet printing method, which is a non-contact type application method, has a limited composition of the liquid that can be used as compared with the contact type application method, so that the required gloss is not sufficiently obtained. Moreover, the liquid is expensive due to technical difficulty such as preparation. On the other hand, in the contact-type coating method, it is difficult to finely change the application amount of the gloss-imparting agent depending on the image.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an image recording method and apparatus capable of solving at least one of the problems 1 to 3.

  One aspect of the present disclosure improves the problem of non-uniform gloss according to Problem 1 by using a contact-type coating method that is less expensive than the non-contact type. In addition, another aspect of the present disclosure provides an image recording method and apparatus capable of obtaining uniform gloss with excellent film durability using a contact-type coating method that is less expensive than a non-contact type. provide.

  In order to achieve the above object, the present disclosure provides the following aspects of the invention.

  An image recording method according to the first aspect includes an image recording step of recording an image on a base material provided with an image quality improving agent, and a contact-type coating method on an image surface of the base material on which an image is recorded by the image recording step A gloss imparting agent coating step for applying a gloss imparting agent, and the gloss imparting agent is a substance that changes its performance by reacting with an image quality improver, and the gloss imparting agent coating step determines the image density of an image. According to the image recording method, a gloss imparting agent is applied to the image surface by using a plate member having a concavo-convex structure with different concavo-convex patterns.

  According to the first aspect, the gloss-imparting agent is transferred from the plate member to the image surface on the substrate, and the coating layer of the gloss-imparting agent covering the image surface is formed. An uneven shape resulting from the uneven pattern of the plate member is formed on the surface of the coating layer. Gloss can be reduced by roughening the surface of the coating layer due to the uneven pattern of the plate member. When using a gloss-imparting agent that changes its performance by reacting with the image quality improver by controlling the surface shape of the coating layer of the gloss-imparting agent by varying the uneven pattern of the plate member according to the image density It is possible to suppress the gloss difference inside.

  According to the first aspect, the gloss can be made uniform by using a contact-type coating method that is less expensive than a non-contact type coating method. According to the first aspect, the entire surface of the image can be covered with the gloss imparting agent, and the durability of the image portion can be improved.

  For example, the image density may be a digital image density calculated from a signal value of image data to be recorded. Since the applied amount of ink is determined based on the digital image density, the image density is correlated with the applied amount of ink used for image recording. “According to the image density” may be understood as “according to the applied amount of ink”.

  Further, the image recording method of the first aspect can be interpreted as a manufacturing method for manufacturing a printed matter that is a recorded matter on which an image is recorded.

  As a second aspect, the image recording method of the first aspect includes an image quality improving agent applying step for applying an image quality improving agent to the substrate, and the image recording step is a group in which the image quality improving agent is applied by the image quality improving agent applying step. An image can be recorded on the material.

  As a third aspect, in the image recording method of the first aspect or the second aspect, the contact-type coating method may be a flexographic printing method using a relief plate as a plate member.

  As a fourth aspect, in the image recording method according to any one of the first aspect to the third aspect, the plate member has a convex portion ratio indicating an area ratio of the convex portions per unit area according to the image density of the image. It can be set as the structure which has different uneven | corrugated structure.

  As a fifth aspect, in the image recording method according to the fourth aspect, the image is compared with a high image density portion which is an image portion having a relatively high image density in an image density range from the minimum image density to the maximum image density. The plate member may be configured such that the convex portion ratio with respect to the high image density portion is smaller than the convex portion ratio with respect to the low image density portion.

  By reducing the convex portion ratio in the plate member, the surface of the coating layer formed after the transfer can be roughened.

  As a sixth aspect, in the image recording method of the fifth aspect, the convex portion ratio with respect to the high image density portion may be 50% or more and less than 100%.

  As a seventh aspect, in the image recording method of the fifth aspect or the sixth aspect, the convex portion ratio of the low image density portion to the high image density portion can be changed depending on the type of the gloss imparting agent to be used.

  As an eighth aspect, in the image recording method according to any one of the first aspect to the seventh aspect, the number of lines of the uneven pattern of the plate member is a line of a gloss imparting agent supply roller that supplies the gloss imparting agent to the plate member. The configuration can be larger than the number.

  As the gloss imparting agent supply roller, for example, an anilox roller having a large number of cells formed on the surface can be used. According to the eighth aspect, it is possible to suppress the dipping phenomenon in which the convex portion of the plate member is buried in the concave portion of the gloss imparting agent supply roller.

  As a ninth aspect, in the image recording method according to any one of the first to eighth aspects, the pattern of the convex portions of the plate member may be a square structure having a quadrangle in plan view.

  As a tenth aspect, in the image recording method according to any one of the first to ninth aspects, the image quality improving agent includes an aggregating agent that aggregates components in the ink, and the gloss imparting agent is an aqueous varnish. It can be.

  As an eleventh aspect, in the image recording method according to any one of the first to tenth aspects, the image quality improving agent may include an acidic substance, and the gloss imparting agent may include an acrylic polymer.

  As a twelfth aspect, in the image recording method according to any one of the first aspect to the eleventh aspect, a coating layer of a gloss imparting agent covering the entire image surface may be formed by the gloss imparting agent coating step. it can.

  As a thirteenth aspect, in the image recording method according to any one of the first aspect to the twelfth aspect, the image recording step may be configured to record an image on a substrate by an ink jet method.

  An image recording apparatus according to a fourteenth aspect includes an image recording unit that records an image on a base material provided with an image quality improver, and a contact-type coating method on an image surface of the base material on which an image is recorded by the image recording unit A gloss imparting agent coating part for applying a gloss imparting agent, and the gloss imparting agent is a substance whose performance is changed by reacting with an image quality improver, and the gloss imparting agent coating part is used for adjusting the image density of an image. The image recording apparatus applies a gloss-imparting agent to the image surface using a plate member having a concavo-convex structure with different concavo-convex patterns.

  In the image recording apparatus of the fourteenth aspect, the same matters as the specific matters of the image recording method specified in the second to thirteenth aspects can be appropriately combined. In this case, the “process (step)” of the process or operation specified in the image recording method can be grasped as an element of a processing unit or a functional unit serving as a unit responsible for the function of the corresponding process or operation.

  According to the present invention, it is possible to achieve uniform gloss using a contact-type coating method that is less expensive than a non-contact type coating method. Moreover, according to this invention, compared with the case where a non-contact-type coating method is used, the printed matter which is excellent in durability can be obtained.

FIG. 1 is an overall configuration diagram illustrating an example of an image recording apparatus according to an embodiment. FIG. 2 is a block diagram illustrating a schematic configuration of a control system of the image recording apparatus. FIG. 3 is a flowchart showing a flow of a series of processing from paper feeding to paper ejection by the image recording apparatus. FIG. 4 is an explanatory view schematically showing the principle of a varnish application method by flexographic printing. FIG. 5 is a graph showing the relationship between gloss and image density when a varnish is applied to the image surface using the varnish plate according to Comparative Example 1. FIG. 6 is an enlarged photograph of the sample used for the measurement of the glossiness, and shows an enlarged photograph of the sample having an image density of a dot ratio of 20%. FIG. 7 is an enlarged photograph of the sample used for measuring the glossiness, and shows an enlarged photograph of the sample having an image density of 100% halftone dot ratio. FIG. 8 is a diagram schematically showing the shape of the varnish plate according to Comparative Example 1. FIG. 9 is a schematic diagram showing a state in which the varnish is supplied to the varnish plate shown in FIG. FIG. 10 is a diagram schematically showing the surface shape of the varnish transferred from the varnish plate shown in FIG. 8 in the low image density portion of the image formed on the substrate. FIG. 11 is a diagram schematically showing the surface shape of the varnish transferred from the varnish plate shown in FIG. 8 in the high image density portion of the image formed on the substrate. FIG. 12 is a diagram schematically showing the shape of the varnish plate applied to the high image density portion in the embodiment of the present invention. FIG. 13 is a schematic plan view showing an example of a pattern of convex portions and concave portions in the varnish plate shown in FIG. FIG. 14 is a developed plan view showing an example of an anilox roller cell. FIG. 15 is a schematic diagram illustrating a state in which the varnish plate and the anilox roller according to the embodiment are in contact with each other. FIG. 16 is a schematic diagram showing a state in which a varnish plate is brought into contact with a substrate on which an image is recorded. FIG. 17 is a schematic diagram showing a state where the varnish is transferred from the varnish plate to the base material. FIG. 18 is a schematic diagram showing an example of a state in which varnish is applied to a low image density portion of an image recorded on a substrate by an image recording method that does not use an undercoat liquid. FIG. 19 is a schematic diagram showing an example of a state in which varnish is applied to a high image density portion of an image recorded on a substrate by applying the technique described in Patent Document 1. FIG. 20 is a table summarizing the conditions of the evaluation experiment performed using the aqueous varnish, the gloss uniformity improvement effect, the surface shape of the varnish surface, and the results of the durability evaluation. FIG. 21 is a table summarizing the conditions of the evaluation experiment conducted using the low-cohesive aqueous varnish, the effect of improving the gloss uniformity, the surface shape of the varnish surface, and the evaluation results of the durability. FIG. 22 is a table summarizing the conditions of the evaluation experiment conducted using the high leveling varnish, the effect of improving the gloss uniformity, the surface shape of the varnish surface, and the evaluation results of the durability. FIG. 23 is a configuration diagram showing an embodiment of an offline type varnish coating apparatus. FIG. 24 is an overall configuration diagram showing an outline of a system configuration of an image recording apparatus in which offline varnish application is performed. FIG. 25 is an overall configuration diagram showing an outline of a system configuration of an image recording apparatus in which online varnish application is performed.

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

<< Variation of the form of the image recording device >>
As a variation of the form of the image recording apparatus to which the present invention can be applied, for example, the following apparatus configuration can be given.

  Embodiment 1: A configuration in which a varnish coating apparatus is integrally incorporated in an inkjet recording apparatus, and the varnish is applied in-line by the varnish coating apparatus in the apparatus after image recording by the inkjet method. The varnish applicator is synonymous with “varnish coater”. The varnish application device incorporated in the apparatus is called an inline varnish coater. Applying varnish in-line using a varnish applicator incorporated in the apparatus is called “in-line varnish coating”.

  Embodiment 2: A form in which a varnish coating apparatus configured separately from the ink jet recording apparatus is used in combination with the ink jet recording apparatus. The “separately configured varnish applicator” may be a stand-alone varnish applicator that can operate independently. The varnish coating apparatus constructed separately is called an off-line varnish coater. Form example 2 can be further classified into the following two forms.

  Embodiment 2-1: An embodiment in which an offline varnish coater installed separately from the ink jet recording apparatus is used and varnish is applied off-line. Applying varnish offline using an offline varnish coater is called "offline varnish coat".

  Embodiment 2-2: An embodiment in which an offline varnish coater is connected to the paper discharge unit of the ink jet recording apparatus, and the varnish is applied on the printed matter output process. Connecting an offline varnish coater to the paper discharge unit and applying varnish is called “online varnish coating”.

  In addition, the specific structure of the offline varnish coater used for the form example 2 is not specifically limited, You may be a commercially available thing. The offline varnish coater preferably has a structure having a heating mechanism for drying the varnish after the varnish application part.

<< Configuration example of image recording apparatus >>
FIG. 1 is an overall configuration diagram illustrating an example of an image recording apparatus according to an embodiment. An image recording apparatus 10 illustrated in FIG. 1 is an ink jet recording apparatus equipped with an inline varnish coater classified as a first embodiment. The image recording apparatus 10 applies a treatment liquid as an undercoat liquid to a paper P corresponding to an example of a base material, and then deposits ink by an inkjet method to record an image, and the paper P on which the image is recorded Is a printing apparatus that coats and outputs the image surface with varnish. The processing liquid is an example of an image quality improving agent. The treatment liquid may be referred to by terms such as a pretreatment liquid, a precoat liquid, or a preconditioning liquid. Varnish is an example of a gloss imparting agent. The varnish used in this embodiment is an aqueous varnish.

  The image recording apparatus 10 can use an ultraviolet curable aqueous ink as a drawing ink. A water-based ink refers to an ink in which a coloring material such as a pigment or a dye is dissolved or dispersed in water and / or a solvent soluble in water. The ultraviolet curable ink refers to an ink that is cured by irradiation with ultraviolet rays (UV). The property of being cured by irradiation of ultraviolet rays or curing is referred to as UV curing. The UV curable ink is called UV ink. Note that the image recording apparatus 10 may use water-based ink that does not have UV curability instead of UV ink.

  The image recording apparatus 10 includes a paper feeding unit 12, a treatment liquid application unit 14, a treatment liquid drying unit 16, an image recording unit 18, an image post-processing unit 20, a varnish application unit 22, and a varnish post-processing unit 24. And a paper discharge unit 26.

<Paper Feeder>
The sheet feeding unit 12 includes a sheet feeding table 30, a sheet feeding device 32, a sheet feeding roller pair 34, a feeder board 36, and a sheet feeding drum 38. The paper feeding unit 12 feeds the paper P one by one. The sheets P are placed on the sheet feeding table 30 in a bundle state in which a plurality of sheets are stacked. The type of the paper P is not particularly limited, and for example, general-purpose printing paper such as high-quality paper, coated paper, and art paper can be used. General-purpose printing paper is not so-called inkjet paper but coated paper or non-coated paper generally used in contact printing such as offset printing, and refers to paper mainly composed of cellulose. . The paper P corresponds to an example of a base material as a recording medium on which an image is formed.

  The sheet feeding device 32 pulls up the sheets P stacked on the sheet feeding table 30 one by one in order from the top and feeds them to the pair of sheet feeding rollers 34. The paper feed roller pair 34 feeds the paper P fed from the paper feed device 32 toward the feeder board 36. The feeder board 36 receives the paper P sent out from the paper feed roller pair 34 and conveys it toward the paper feed drum 38. The paper supply drum 38 receives the paper P conveyed by the feeder board 36 and conveys the received paper P toward the processing liquid coating unit 14. The paper supply drum 38 conveys the paper P along a certain conveyance path by rotating the gripper 38A by gripping the leading end of the paper P.

<Processing liquid application part>
The treatment liquid application unit 14 performs a process for applying the treatment liquid to the paper P. The treatment liquid is a liquid having a function of aggregating, insolubilizing or thickening the color material component in the ink. The processing liquid used in the present embodiment is composed of a liquid containing an aggregating agent that aggregates the color material components in the ink used in the image recording unit 18. The flocculant may be a compound that can change the pH (pH) of the ink composition, a polyvalent metal salt, or a polyallylamine. Preferred examples of the compound capable of lowering the pH include acidic substances having high water solubility. An acidic substance may be used individually by 1 type, and may use 2 or more types together.

  The treatment liquid application unit 14 includes a treatment liquid drum 42 and a treatment liquid application device 44. By applying such a treatment liquid in advance to form an image, the spread and / or movement of ink is suppressed, and a high-quality image can be formed.

  The processing liquid drum 42 constitutes a part of the paper P transport mechanism. The processing liquid drum 42 receives the paper P from the paper supply drum 38 and conveys the received paper P toward the processing liquid drying unit 16. The treatment liquid drum 42 conveys the paper P wound around the peripheral surface by rotating the gripper 42 </ b> A by gripping the front end of the paper P. The paper P is wound around the processing liquid drum 42 and conveyed with the first surface thereof directed outward. The first surface of the paper P corresponds to an image forming surface on which an image is formed with ink.

  The processing liquid application device 44 applies the processing liquid to the first surface of the paper P conveyed by the processing liquid drum 42. The treatment liquid application device 44 includes a treatment liquid application roller 44A, a treatment liquid container 44B, a treatment liquid supply roller 44C, and a doctor blade (not shown). The processing liquid is stored in the processing liquid container 44B, and a part of the processing liquid supply roller 44C is immersed in the processing liquid in the processing liquid container 44B. The treatment liquid weighed to a certain amount by the treatment liquid supply roller 44C is transferred from the treatment liquid container 44B to the surface of the treatment liquid application roller 44A, and the treatment liquid application roller 44A is moved to the paper in the process of transporting the paper P by the treatment liquid drum 42. By pressing and contacting the surface of P, the processing liquid is transferred from the processing liquid application roller 44A to the surface of the paper P.

  Note that the treatment liquid application method is not limited to the roller application method. For example, as an example of another coating method of the treatment liquid, a method such as coating using a blade, ejection using an inkjet method, or spraying using a spray method may be employed.

  The paper P delivered from the paper supply drum 38 to the treatment liquid drum 42 passes through the treatment liquid application device 44 in the process of being conveyed by the treatment liquid drum 42, and the treatment liquid is applied during the passage.

<Processing liquid drying section>
The processing liquid drying unit 16 performs processing for drying the processing liquid applied to the paper P. The processing liquid drying unit 16 includes a processing liquid drying drum 46, a paper transport guide 48, and a processing liquid dryer 50.

  The processing liquid drying drum 46 constitutes a part of the paper P transport mechanism. The processing liquid drying drum 46 receives the paper P from the processing liquid drum 42 and conveys the received paper P toward the image recording unit 18. The processing liquid drying drum 46 conveys the sheet P along a certain conveyance path by gripping and rotating the leading end of the sheet P with the gripper 46A. The sheet P is conveyed in a state where the first surface, which is the treatment liquid application surface, is directed to the inside of the treatment liquid drying drum 46.

  The paper transport guide 48 is disposed along the transport path of the paper P by the treatment liquid drying drum 46 and guides the transport of the paper P. The paper P is transported while sliding on the paper transport guide 48. The sheet P is transported while the second surface opposite to the first surface coated with the treatment liquid slides on the sheet transport guide 48.

  The treatment liquid dryer 50 blows hot air on the first surface of the paper P conveyed by the treatment liquid drying drum 46 to heat the first surface. The treatment liquid dryer 50 is disposed inside the treatment liquid drying drum 46. The treatment liquid dryer 50 includes a heat source such as a halogen heater or an infrared (IR) heater, and a blowing unit that blows a gas heated by the heat source. The gas heated by the heat source is, for example, air. Other gases may be used instead of or in addition to air. For example, a fan or a blower can be used as the blowing means. When the processing liquid dryer 50 is composed of a heater and a blower, the heating intensity of the processing liquid dryer 50 can be controlled by the number of heaters lit and / or the lighting duty.

  The sheet P transferred from the paper supply drum 38 to the treatment liquid drying drum 46 is blown with hot air from the treatment liquid dryer 50 on the first surface in the process of being conveyed by the treatment liquid drying drum 46. Thereby, the 1st surface which is a process liquid application surface is heated, and the solvent component in a process liquid is dried and removed. As a result, an ink aggregation layer is formed on the first surface of the paper P. The ink aggregating layer refers to a layer of an ink aggregating agent contained in the processing liquid. The treatment liquid drying unit 16 evaporates moisture in the treatment liquid, and an ink aggregation layer, which is a thin film layer of the ink aggregation agent of the treatment liquid, is formed on the first surface of the paper P.

<Image recording part>
The image recording unit 18 performs a process of recording an image on the first surface of the paper P by an inkjet method. The image recording unit 18 includes an image recording drum 52, a sheet pressing roller 54, ink jet heads 56 </ b> C, 56 </ b> M, 56 </ b> Y, 56 </ b> K, and an inline sensor 58.

  The image recording drum 52 constitutes a part of the paper P transport mechanism. The image recording drum 52 receives the paper P from the processing liquid drying drum 46 and conveys the received paper P toward the image post-processing unit 20. The image recording drum 52 grips and rotates the leading end of the paper P with the gripper 52A, thereby winding and transporting the paper P around the peripheral surface. At this time, in order to ensure the flatness of the paper P, the paper P is conveyed by being attracted to the peripheral surface of the image recording drum 52. The flatness of the paper P indicates that there is no float or wrinkle. A large number of suction holes (not shown) are formed on the peripheral surface of the image recording drum 52, and the paper P is sucked and held on the peripheral surface of the image recording drum 52 by the negative pressure generated in the suction holes. . Note that the image recording drum 52 is not limited to the configuration in which the paper P is sucked and fixed by negative pressure suction, and may be configured to suck and hold the paper P by electrostatic suction, for example. The paper P is wound around the image recording drum 52 and conveyed with the first surface facing outward.

  The paper pressing roller 54 presses the paper P toward the image recording drum 52 to bring the paper P into close contact with the peripheral surface of the image recording drum 52.

  The inkjet heads 56C, 56M, 56Y, and 56K eject ink droplets from a large number of nozzles provided on the respective nozzle surfaces. The inkjet head 56 </ b> C is a recording head that discharges cyan (C) ink droplets. The inkjet head 56M is a recording head that ejects magenta (M) ink droplets. The inkjet head 56Y is a recording head that discharges yellow (Y) ink droplets. The inkjet head 56K is a recording head that ejects black (K) ink droplets.

  Each of the inkjet heads 56C, 56M, 56Y, and 56K is supplied with ink from an ink tank (not shown) that is an ink supply source of the corresponding color via a pipe path (not shown). Each of the inkjet heads 56C, 56M, 56Y, and 56K is a line-type inkjet head. In other words, the inkjet heads 56C, 56M, 56Y, and 56K are constituted by line heads having nozzle rows in which nozzles are arranged over a length corresponding to the drawable range of the maximum paper width.

  Although not shown in FIG. 1, a plurality of nozzles serving as ink ejection openings are two-dimensionally arranged on the nozzle surfaces of the inkjet heads 56C, 56M, 56Y, and 56K. “Nozzle surface” refers to an ejection surface on which nozzles are formed, and is synonymous with terms such as “ink ejection surface” or “nozzle formation surface”. A nozzle arrangement of a plurality of nozzles arranged two-dimensionally is called a “two-dimensional nozzle arrangement”.

  Each of the inkjet heads 56C, 56M, 56Y, and 56K can be configured by connecting a plurality of head modules in the paper width direction. The paper width here refers to the paper width in a direction orthogonal to the conveyance direction of the paper P. Each of the inkjet heads 56C, 56M, 56Y, and 56K is a nozzle capable of recording an image with a specified recording resolution in one scan of the entire recording area of the paper P with respect to the paper width direction orthogonal to the transport direction of the paper P. This is a line type recording head having columns. Such a recording head is also called a “full line type recording head” or a “page wide head”.

  The specified recording resolution may be a recording resolution predetermined by the image recording apparatus 10, or a recording resolution set by user selection or by automatic selection by a program corresponding to the print mode. Also good. The recording resolution can be set to 1200 dpi, for example. “Dpi” means dot per inch and is a unit notation representing the number of dots (points) per inch. One inch is 25.4 millimeters [mm].

  The paper width direction perpendicular to the paper P transport direction may be referred to as the nozzle row direction of the line head, and the paper P transport direction may be referred to as the nozzle row vertical direction.

  In the case of an inkjet head having a two-dimensional nozzle array, the projection nozzle array in which the nozzles in the two-dimensional nozzle array are projected (orthographically projected) along the nozzle array direction achieves the maximum recording resolution in the nozzle array direction. It can be considered that the nozzle density is equivalent to a single nozzle row in which each nozzle is arranged at approximately equal intervals. The “substantially equidistant” means that the droplet ejection points that can be recorded by the ink jet recording apparatus are substantially equidistant. For example, the concept of “equally spaced” includes a case where the distance is slightly different in consideration of manufacturing errors and / or movement of droplets on the medium due to landing interference. The projection nozzle row corresponds to a substantial nozzle row. Considering the projection nozzle row, it is possible to associate a nozzle number representing the nozzle position with each nozzle in the arrangement order of the projection nozzles arranged along the nozzle row direction.

  The nozzle arrangement form in each of the inkjet heads 56C, 56M, 56Y, and 56K is not limited, and various nozzle arrangement forms can be adopted. For example, instead of a matrix-like two-dimensional array, a linear array of lines, a V-shaped nozzle array, a polygonal nozzle array such as a W-shape with a V-shaped array as a repeating unit, and the like are also possible. It is.

  The inkjet heads 56C, 56M, 56Y, and 56K are arranged on the conveyance path of the paper P at a constant interval, and the inkjet heads 56C, 56M, 56Y, and 56K extend in a direction orthogonal to the conveyance direction of the paper P. To be installed. The direction orthogonal to the conveyance direction of the paper P is a direction parallel to the rotation axis of the image recording drum 52.

  Ink droplets are ejected from at least one of the inkjet heads 56C, 56M, 56Y, and 56K toward the sheet P conveyed by the image recording drum 52, and the ejected droplets adhere to the sheet P. Thus, an image is recorded on the paper P.

  The image recording drum 52 functions as a means for relatively moving the ink jet heads 56C, 56M, 56Y, 56K and the paper P. The ejection timings of the inkjet heads 56C, 56M, 56Y, and 56K are synchronized with a rotary encoder signal obtained from a rotary encoder installed on the image recording drum 52. In FIG. 1, the rotary encoder is not shown. The ejection timing is the timing at which ink droplets are ejected, and is synonymous with the droplet ejection timing.

  In this example, the configuration using four colors of CMYK ink is exemplified, but the combination of ink color and number of colors is not limited to this embodiment, and light ink, dark ink, special color ink, etc. are used as necessary. May be added. For example, a configuration in which an inkjet head that ejects light-colored ink such as light cyan and light magenta is added, and / or a configuration in which an inkjet head that ejects a special color ink such as green or orange is added. Also, the arrangement order of the ink jet heads for each color is not particularly limited.

  The inline sensor 58 is an apparatus that optically reads an image recorded on the paper P by the inkjet heads 56C, 56M, 56Y, and 56K and generates electronic image data indicating the read image. The in-line sensor 58 includes an imaging device that captures an image recorded on the paper P and converts it into an electrical signal indicating image information. The in-line sensor 58 may include an imaging optical device, an illumination optical system that illuminates a reading target, and a signal processing circuit that processes a signal obtained from the imaging device and generates digital image data.

  The inline sensor 58 is preferably configured to be able to read a color image. In the inline sensor 58 of this example, for example, a color CCD linear image sensor is used as an imaging device. CCD is an abbreviation for Charge-Coupled Device and refers to a charge coupled device. The color CCD linear image sensor is an image sensor in which light receiving elements having color filters of R (red), G (green), and B (blue) colors are arranged linearly. Instead of the color CCD linear image sensor, a color CMOS linear image sensor can be used. CMOS is an abbreviation for Complementary Metal Oxide Semiconductor and refers to a complementary metal oxide semiconductor.

  The inline sensor 58 reads an image on the paper P while the paper P is being conveyed by the image recording drum 52. The image reading apparatus installed in the paper conveyance path in this way is sometimes called an “inline scanner”. The inline sensor 58 may be a camera.

  When the paper P on which an image is recorded using at least one of the inkjet heads 56C, 56M, 56Y, and 56K passes through the reading area of the inline sensor 58, the image on the paper P is read. As an image to be recorded on the paper P, in addition to a user image to be printed specified in a print job, a defective nozzle detection pattern for inspecting the ejection state of each nozzle, a test pattern for print density correction, and print density unevenness correction Test patterns, and various other test patterns.

  Based on the data of the read image read by the inline sensor 58, the print image is inspected to determine whether there is an abnormality in image quality. Further, based on the read image data read by the in-line sensor 58, it is possible to obtain information such as the density of the print image and ejection defects of the inkjet heads 56C, 56M, 56Y, and 56K.

<Image post-processing section>
The image post-processing unit 20 performs post-processing of the image recorded on the paper P. The image post-processing unit 20 performs an ink drying process and an ink UV curing process. The ink drying process is a process for drying the ink by heating the first surface side of the paper P on which an image is recorded. The ink UV curing process is a process of irradiating UV light onto the image surface after the ink drying process to cure the UV.

  The image post-processing unit 20 includes an image post-processing chain gripper 64, an ink drying unit 20A, an ink UV curing unit 20B, and a first guide plate 72. The image post-processing chain gripper 64 constitutes a part of the transport mechanism of the paper P.

  The image post-processing chain gripper 64 receives the paper P from the image recording drum 52 and conveys the received paper P toward the varnish application unit 22. The image post-processing chain gripper 64 includes an endless chain 64A that travels along a certain travel path. The gripper 64B provided on the chain 64A grips the leading end of the paper P, thereby Transport along the transport path.

  The image post-processing chain gripper 64 of this example has a structure in which a pair of endless chains 64A are wound around a pair of first sprockets 64C and a pair of second sprockets 64D. FIG. 1 shows only one of the pair of first sprockets 64C, the pair of second sprockets 64D, and the pair of chains 64A.

  A plurality of grippers 64B are provided in the chain 64A at regular intervals. That is, the image post-processing chain gripper 64 has a structure in which a plurality of grippers 64B are arranged at a plurality of positions in the feed direction (length direction) of the chain 64A. The image post-processing chain gripper 64 has a structure in which a plurality of grippers 64B are disposed between the pair of chains 64A along the width direction of the paper width direction. The sheet P is transported with the first surface thereof directed to the inside of the image post-processing chain gripper 64.

  The first guide plate 72 is a member that guides the conveyance of the paper P by the image post-processing chain gripper 64. The paper P conveyed by the image post-processing chain gripper 64 is conveyed while sliding on the guide surface of the first guide plate 72. At this time, the paper P slides on the guide surface of the first guide plate 72 while being sucked from a number of suction holes provided on the guide surface of the first guide plate 72. As a result, the paper P is conveyed while a certain tension is applied.

  The ink drying unit 20 </ b> A performs an ink drying process on the paper P conveyed by the image post-processing chain gripper 64. The ink drying unit 20A heats the image surface of the paper P conveyed by the image post-processing chain gripper 64 and performs a process of drying the ink. In the present embodiment, hot air is blown onto the image surface to heat the image and dry the ink. For this reason, the ink drying unit 20A includes an ink dryer 68 that blows hot air. The ink dryer 68 includes, for example, a heat source such as a halogen heater or an infrared heater, and a blowing unit that blows a gas heated by the heat source.

  The ink dryer 68 is disposed inside the image post-processing chain gripper 64. When the ink dryer 68 is composed of a heater and a blowing means, the heating intensity of the ink dryer 68 can be controlled by the number of heaters lit and / or the lighting duty.

  Further, the ink drying unit 20A may include a temperature sensor (not shown) in order to monitor the temperature of the heated image surface. The temperature sensor is composed of, for example, a radiation thermometer. A radiation thermometer is a thermometer that measures the temperature of an object by measuring the intensity of infrared or visible light emitted from the object.

  The ink UV curing unit 20B performs an ink UV curing process that irradiates UV light onto the image surface of the paper P conveyed by the image post-processing chain gripper 64 to cure the ink. The ink UV curing unit 20B includes a UV irradiation device 69 that includes a UV light source. The UV irradiation device 69 is disposed inside the image post-processing chain gripper 64.

  The paper P is first transported by the image post-processing chain gripper 64, so that it first passes through the ink drying unit 20A. Then, hot air is blown to the first surface of the paper P during the period of passing through the ink drying unit 20A, the image surface is heated, and the ink is dried. The paper P that has passed through the ink drying unit 20A then passes through the ink UV curing unit 20B. Then, the UV light is irradiated onto the first surface of the paper P during the period of passing through the ink UV curing unit 20B. As a result, the ink is cured and the image is fixed on the paper P.

  In addition, when using the water-based ink which does not have UV curability instead of UV ink, it can be set as the form which abbreviate | omitted the ink UV hardening part 20B of the image post-processing part 20. FIG.

<Varnish application part>
The varnish application unit 22 performs a process of applying varnish to the surface of the image recorded on the paper P. Varnish is an example of a gloss imparting agent, and an aqueous varnish is used in the present embodiment. The varnish application unit 22 includes a varnish drum 65 and a varnish application unit 80. The varnish application part 22 is an example of a “gloss imparting agent application part”.

  The varnish drum 65 constitutes a part of the paper P transport mechanism. The varnish drum 65 receives the paper P from the image post-processing chain gripper 64 and conveys the received paper P toward the varnish post-processing unit 24. The configuration of the varnish drum 65 is the same as that of the processing liquid drum 42, and the paper P is wound around the peripheral surface and conveyed by gripping and rotating the front end of the paper P with the gripper 65A. At this time, the paper P is conveyed with the first surface serving as the varnish application surface facing outward.

  The varnish application unit 80 is a unit for applying varnish to the image surface of the paper P conveyed by the varnish drum 65 by a contact-type application method. The varnish application unit 80 includes a varnish application roller 82, a varnish supply roller 84, and a varnish chamber 86.

  The varnish application roller 82 includes a varnish plate that comes into contact with the image surface of the paper P on which an image is recorded, and applies the varnish to the image surface of the paper P. The varnish application roller 82 is provided so as to be able to contact / separate with respect to the varnish drum 65, and is contacted / separated with respect to the varnish drum 65 in accordance with the timing when the paper P passes.

  The varnish supply roller 84 supplies varnish to the varnish plate of the varnish application roller 82. The varnish supply roller 84 is provided so as to be able to contact / separate from the varnish application roller 82. The varnish supply roller 84 is a measuring roller capable of measuring a certain amount of varnish. An anilox roller can be used as the varnish supply roller 84. The varnish application roller 82 is given a varnish with a constant thickness on the peripheral surface thereof by contacting the varnish supply roller 84.

  The varnish chamber 86 supplies varnish to the varnish supply roller 84. The varnish chamber 86 is a doctor chamber provided with a doctor blade. The varnish chamber 86 supplies varnish to the surface of the varnish supply roller 84 with a certain thickness. A varnish supply device (not shown) is connected to the varnish chamber 86, and the varnish is circulated and supplied.

  The varnish supplied from the varnish chamber 86 to the varnish supply roller 84 is supplied to the surface of the varnish application roller 82 with a constant thickness by the varnish supply roller 84 coming into contact with the varnish application roller 82. The varnish application roller 82 supplied with the varnish is brought into contact with the first surface (image forming surface) of the paper P conveyed by the varnish drum 65, so that the varnish is fixed on the first surface of the paper P. Applied in thickness.

<Variet aftertreatment>
The varnish post-processing unit 24 performs post-processing of the varnish applied to the image surface in the varnish application unit 22. The post-processing performed by the varnish post-processing unit 24 includes a varnish drying process for drying the varnish applied to the image surface of the paper P. The varnish drying process of this example is a process of heating the first surface side of the paper P coated with the varnish to dry the varnish. The varnish post-processing unit 24 includes a varnish drying unit 24B that performs a process of heating the image surface on which the varnish is applied. The varnish post-processing unit 24 includes a varnish post-processing chain gripper 66, a varnish drying unit 24 </ b> B, and a second guide plate 75.

  The varnish post-processing chain gripper 66 constitutes a part of the paper P transport mechanism. The varnish post-processing chain gripper 66 receives the paper P from the varnish drum 65 and conveys the received paper P toward the paper discharge unit 26. The varnish post-processing chain gripper 66 includes an endless chain 66A that travels along a certain travel path, and the gripper 66B provided on the chain 66A grips the leading end of the paper P, thereby Transport along the transport path. The paper P is conveyed in a state where the first surface is directed to the inside of the varnish post-processing chain gripper 66.

  The varnish post-processing chain gripper 66 of this example has a structure in which a pair of endless chains 66A are wound around a pair of third sprocket 66C and a pair of fourth sprocket 66D. FIG. 1 shows only one of the pair of third sprocket 66C, the pair of fourth sprocket 66D, and the pair of chains 66A.

  A plurality of grippers 66B are provided in the chain 66A at regular intervals. That is, the varnish post-processing chain gripper 66 has a structure in which a plurality of grippers 66B are arranged at a plurality of positions in the feed direction (length direction) of the chain 66A. Further, the varnish post-processing chain gripper 66 has a structure in which a plurality of grippers 66B are disposed between the pair of chains 66A along the width direction of the paper width direction.

  The second guide plate 75 is a member that guides the conveyance of the sheet P by the varnish post-processing chain gripper 66. The paper P conveyed by the varnish post-processing chain gripper 66 is conveyed while sliding on the guide surface of the second guide plate 75. At this time, the paper P slides on the guide surface of the second guide plate 75 while being sucked from a large number of suction holes provided on the guide surface of the second guide plate 75. As a result, the paper P is conveyed while a certain tension is applied.

  The varnish drying unit 24 </ b> B heats the varnish application surface of the paper P conveyed by the chain gripper 66 for varnish post-processing and performs a process of drying the varnish. The varnish drying section 24B of the present embodiment is configured to blow hot air on the varnish application surface of the paper P to dry the varnish. The varnish drying unit 24B includes a varnish dryer 74 that blows hot air. The varnish dryer 74 includes, for example, a heat source such as a halogen heater or an infrared heater, and a blowing unit that blows a gas heated by the heat source. The varnish dryer 74 is disposed inside the chain gripper 66 for varnish post-treatment. When the varnish dryer 74 is composed of a heater and a blower, the heating intensity of the varnish dryer 74 can be controlled by the number of heaters lit and / or the lighting duty.

  The paper P delivered from the varnish drum 65 to the varnish post-processing chain gripper 66 is sent to the paper discharge unit 26 via the inclined conveyance path 67. The varnish dryer 74 is installed in the inclined conveyance path 67, and a varnish drying process is performed on the paper P that passes through the inclined conveyance path 67.

<Paper output section>
The paper discharge unit 26 is provided at the subsequent stage of the varnish drying unit 24B. The paper discharge unit 26 collects the paper P that has been subjected to a series of processes of application of processing liquid → image recording → image post-processing → varnish coat → varnish drying. The paper discharge unit 26 includes a paper discharge tray 76 that stacks and collects paper P.

  The gripper 66 </ b> B of the varnish post-processing chain gripper 66 releases the paper P on the paper discharge tray 76 and stacks the paper P on the paper discharge tray 76. The paper discharge tray 76 is provided with a sheet pad (not shown) so that the sheets P are stacked in an orderly manner.

  The paper discharge tray 76 is provided so as to be lifted and lowered by a paper discharge tray lifting / lowering device (not shown). The discharge platform lifting device is controlled in conjunction with the increase / decrease of the paper P stacked on the paper discharge tray 76 so that the uppermost paper P is always positioned at a certain height. The paper table 76 is moved up and down.

<< Description of Control System of Image Recording Apparatus >>
FIG. 2 is a block diagram illustrating a schematic configuration of a control system of the image recording apparatus 10. As shown in FIG. 2, the image recording apparatus 10 includes a system controller 200, a communication unit 202, an image memory 204, a conveyance control unit 210, a paper feed control unit 212, a processing liquid application control unit 214, a processing liquid drying control unit 216, An image recording control unit 218, an image post-processing control unit 220, a varnish application control unit 222, a varnish drying control unit 224, a paper discharge control unit 226, an operation unit 230, a display unit 232, and the like are provided.

  The system controller 200 functions as a control unit that performs overall control of each unit of the image recording apparatus 10 and also functions as a calculation unit that performs various calculation processes. The system controller 200 includes a CPU (Central Processing Unit) 200A, a ROM (Read Only Memory) 200B, and a RAM (Random Access Memory) 200C.

  The communication unit 202 includes a required communication interface, and transmits and receives data to and from the host computer 260 connected to the communication interface.

  The image memory 204 functions as a temporary storage unit for various data including image data. The image memory 204 reads and writes data through the system controller 200. Image data captured from the host computer 260 via the communication unit 202 is temporarily stored in the image memory 204.

  The conveyance control unit 210 controls the operation of the conveyance system 250 for the paper P in the image recording apparatus 10. The transport system 250 includes the paper feed drum 38, the processing liquid drum 42, the processing liquid drying drum 46, the image recording drum 52, the image post-processing chain gripper 64, the varnish drum 65, and the varnish post-processing chain gripper described in FIG. 66 is included. The conveyance control unit 210 controls conveyance of the paper P from the paper supply unit 12 to the paper discharge unit 26 in accordance with a command from the system controller 200.

  The paper feed control unit 212 controls the operation of the paper feed unit 12 in accordance with a command from the system controller 200. That is, the operation of the paper feeding unit 12 is controlled so that the paper P is fed at the designated paper feeding speed.

  The processing liquid drying control unit 216 controls the operation of the processing liquid drying unit 16 in response to a command from the system controller 200. That is, the operation of the treatment liquid dryer 50 is controlled so that the image surface of the paper P is heated with the instructed heating intensity.

  The image recording control unit 218 controls the operation of the image recording unit 18 in accordance with a command from the system controller 200. That is, ink ejection by the inkjet heads 56C, 56M, 56Y, and 56K is controlled so that the instructed image is recorded as the paper P passes. Further, the reading of the image by the inline sensor 58 is controlled in accordance with the passage of the paper P.

  The image post-processing control unit 220 includes an ink drying control unit 220A and an ink UV curing control unit 220B.

  The ink drying control unit 220A controls the operation of the ink drying unit 20A according to a command from the system controller 200. The ink drying control unit 220A controls the operation of the ink dryer 68 so as to heat the image surface of the conveyed paper P with the instructed heating intensity. The heating intensity can be set as parameters such as the thickness of the paper, the type of paper, the total ink amount of the image to be recorded on the paper, and the type of single-sided / double-sided recording. The information on these parameters may be configured to be input by the user from the operation unit 230, or may be automatically acquired from the information on the print command. In general, information on sheet thickness, sheet type, and single-sided / double-sided recording type is input before image recording as information necessary for image recording. Further, the ink amount of an image can be obtained by calculation from information of image data to be recorded.

  The ink UV curing control unit 220B controls the operation of the ink UV curing unit 20B in response to a command from the system controller 200. The ink UV curing control unit 220B controls the operation of the UV irradiation device 69 so that the instructed amount of UV light is irradiated onto the image surface as the paper P passes.

  The varnish application control unit 222 controls the operation of the varnish application unit 22 in accordance with a command from the system controller 200. The varnish application control unit 222 controls the operation of the varnish application unit 80 so that the varnish is applied to the image surface with the specified application amount in accordance with the passage of the paper P.

  The varnish drying control unit 224 controls the operation of the varnish drying unit 24 </ b> B in response to a command from the system controller 200. The varnish drying control unit 224 sets the heating intensity of the varnish dryer 74.

  The paper discharge control unit 226 controls the operation of the paper discharge unit 26 in response to a command from the system controller 200.

  The operation unit 230 includes operation members such as operation buttons, a keyboard, and a touch panel, and sends operation information input from the operation members to the system controller 200. The system controller 200 executes various processes in accordance with the operation information sent from the operation unit 230.

  The display unit 232 includes a display device such as an LCD (Liquid Crystal Display) panel, and displays various kinds of setting information, abnormality information, and the like on the display device in response to a command from the system controller 200.

  Information on the image read by the inline sensor 58 is stored in a predetermined memory such as the RAM 200C via the system controller 200.

  The system controller 200, the conveyance control unit 210, the paper feed control unit 212, the processing liquid application control unit 214, the processing liquid drying control unit 216, the image recording control unit 218, the image post-processing control unit 220, and the varnish application control illustrated in FIG. The hardware structure of a processing unit (processing unit) that executes various processes, such as the unit 222, the varnish drying control unit 224, and the paper discharge control unit 226, is the following various processors.

  Various processors are processors whose circuit configuration can be changed after manufacturing, such as a CPU (Central Processing Unit) and a FPGA (Field Programmable Gate Array), which are general-purpose processors that execute programs and function as various processing units. Examples include a dedicated electric circuit that is a processor having a circuit configuration specifically designed to execute a specific process such as a programmable logic device (PLD) or an application specific integrated circuit (ASIC). A program is synonymous with software.

  One processing unit may be configured by one of these various processors, or may be configured by two or more processors of the same type or different types. For example, one processing unit may be configured by a plurality of FPGAs or a combination of a CPU and an FPGA. Further, the plurality of processing units may be configured by one processor. As an example of configuring a plurality of processing units with one processor, first, as represented by a computer such as a client or server, one processor is configured with a combination of one or more CPUs and software. There is a form in which the processor functions as a plurality of processing units. Secondly, as represented by System On Chip (SoC), etc., there is a form of using a processor that realizes the functions of the entire system including a plurality of processing units with one IC (Integrated Circuit) chip. is there. As described above, various processing units are configured using one or more of the various processors as a hardware structure.

  Further, the hardware structure of these various processors is more specifically an electric circuit (circuitry) in which circuit elements such as semiconductor elements are combined.

<Image recording method>
FIG. 3 is a flowchart showing a flow of a series of processing from paper feeding to paper ejection by the image recording apparatus 10.

  First, the paper P is fed from the paper feed unit 12 (step S1: paper feed process).

  The fed paper P is conveyed to the processing liquid application unit 14 and the processing liquid is applied to the first surface of the paper P (step S2: processing liquid application process).

  The paper P coated with the treatment liquid is conveyed to the treatment liquid drying unit 16 and the applied treatment liquid is dried (step S3: treatment liquid drying step).

  The paper P from which the treatment liquid has been dried is conveyed to the image recording unit 18 and an image is recorded on the first surface of the paper P using ink (step S4: image recording process). Specifically, ink droplets ejected from the inkjet heads 56C, 56M, 56Y, and 56K are ejected onto the first surface of the paper P, and an image is recorded on the first surface of the paper P.

  The paper P on which the image is recorded is conveyed to the image post-processing unit 20 and the post-processing of the image recorded on the first surface is performed. Specifically, first, in the ink drying unit 20A, hot air is blown onto the image surface to dry the ink (step S5: ink drying step).

  The paper P that has passed through the ink drying unit 20A is then irradiated with UV light on the image surface in the ink UV curing unit 20B to cure the ink (step S6: ink UV curing step).

  After the post-processing of the image including the ink drying process (step S5) and the ink UV curing process (step S6) is completed, the paper P is conveyed to the varnish application unit 22 and varnish is applied to the image surface (step S7). : Varnish application process).

  The paper P on which the varnish has been applied is conveyed to the varnish post-processing section 24, where the applied varnish is post-processed. Here, the post-treatment of the varnish is a varnish drying process for drying the varnish (Step S8: Varnish drying step).

  Thereafter, the paper P is conveyed to the paper discharge unit 26 and discharged onto the paper discharge tray 76 (step S9: paper discharge step).

  In the flowchart shown in FIG. 3, the treatment liquid application process in step S <b> 2 is an example of the “image quality improving agent application process”. The varnish application process in step S7 is an example of a “gloss imparting agent application process”.

《Outline of varnish application method by flexographic printing method》
FIG. 4 is an explanatory view schematically showing the principle of a varnish application method by flexographic printing. The flexographic varnish coating apparatus 300 includes a doctor chamber 302, an anilox roller 304, a plate cylinder 306, and an impression cylinder 308. A plate 310 made of a plate material made of resin and / or rubber is wound around the plate cylinder 306. The surface of the plate 310 has a concavo-convex structure and includes a convex portion 312 and a concave portion 314.

  The doctor chamber 302 includes a container 320 and a doctor blade 322. The container 320 contains the liquid of the varnish 330. The varnish in the container 320 is supplied to the anilox roller 304.

  The anilox roller 304 is a measuring roller in which a large number of cells are carved on the outer peripheral surface, and measures the liquid by the cells. The varnish measured by the anilox roller 304 is transferred from the anilox roller 304 to the plate 310.

  The paper P is fed between the plate cylinder 306 and the impression cylinder 308, and the varnish is transferred from the plate 310 to the paper P.

  The varnish chamber 86 described in FIG. 1 corresponds to the doctor chamber 302 shown in FIG. The varnish supply roller 84 described in FIG. 1 corresponds to the anilox roller 304 illustrated in FIG. The varnish application roller 82 described in FIG. 1 corresponds to the plate cylinder 306 including the plate 310 shown in FIG. The varnish drum 65 shown in FIG. 1 corresponds to the impression cylinder 308 shown in FIG.

  The application method by the flexographic printing method is an example of a contact-type application method. A plate used when applying a varnish by a contact type application method is called a “varnish plate”. The plate 310 shown in FIG. 4 is an example of a varnish plate. As the plate 310, a plate-like plate material processed may be wound around the plate cylinder 306, or a sleeve-shaped plate material processed may be attached to the plate cylinder 306.

<< Explanation of Problem 1 >>
FIG. 5 is a graph showing the relationship between gloss and image density when a varnish is applied to the image surface using the varnish plate according to Comparative Example 1. The horizontal axis represents the image density. The image density is a digital image density calculated from the signal value of the image data, and represents the ink recording rate. The image density may be understood as a droplet ejection rate or a halftone dot rate. The vertical axis represents 60 ° gloss measured using a gloss meter. The varnish plate of Comparative Example 1 is a plate provided with a single convex portion that uniformly applies a certain amount of varnish to the entire image surface of the paper P on which an image is recorded.

  When the varnish is applied to the image surface of the paper P using the varnish plate according to Comparative Example 1, the glossiness value changes depending on the image density, as shown in FIG. In particular, the glossiness is low in a region where the image density including the non-image portion is low, and the glossiness tends to increase as the image density exceeds 60% and becomes high. Thus, there is non-uniform gloss due to the difference in image density of recorded images. In the example of FIG. 5, the maximum value of glossiness is about 75% and the minimum value is about 45%. If the gloss difference ΔG, which is the difference between the maximum value and the minimum value of the glossiness, is large, it becomes a factor of deteriorating the quality of the printed matter. The uniformity of gloss can be evaluated using the difference between the maximum and minimum glossiness as an index.

  6 and 7 are enlarged photographs of samples used for the measurement of glossiness. FIG. 6 is a photograph of a sample having an image density with a halftone dot ratio of 20%. FIG. 7 is a photograph of a sample having an image density of 100% halftone dots. In both the samples shown in FIGS. 6 and 7, the vertical direction of the drawings is the paper feeding direction.

  In the sample shown in FIG. 6, a wrinkled shadow appears along the horizontal direction. This shadow is a shadow of the groove portion in the concavo-convex shape on the surface of the varnish layer, and indicates that the surface shape of the varnish layer is rough. The glossiness measured in the horizontal direction of the sample shown in FIG. 6 was 41, and the glossiness measured in the vertical direction was 27. The sample shown in FIG. 7 has a better surface shape of the varnish layer than the sample of FIG. The glossiness measured in the horizontal direction of the sample in FIG. 7 was 66, and the glossiness measured in the vertical direction was 46.

<Consideration of the principle of gloss reduction>
As described above, when a varnish as a gloss-imparting agent is applied to an image recorded by a method using an undercoat liquid as an image quality improver, there arises a problem of uneven glossiness with different glossiness depending on the image density. Specifically, the gloss in the non-image portion, particularly in the halftone portion, is reduced with respect to the solid portion that is the image region having the maximum image density.

  The principle of such gloss reduction is estimated as follows. For example, when a liquid containing an acidic substance as an aggregating agent that aggregates the ink composition is used as the undercoat liquid, the dispersion state of the polymer component dispersed in the varnish is unstable due to the acid component contained in the undercoat liquid. It is estimated that the polymer component is aggregated. Among the polymer components in the varnish, the substance that easily reacts with the acid component of the undercoat liquid is considered to be, for example, an acrylic polymer.

  An important point of the principle described above is that the component of the undercoat liquid reacts with the component of the varnish, and the performance after varnish application (gloss in this case) changes depending on the presence or absence of the undercoat liquid. The principle is not limited to the mechanism by which the acid and the polymer in the varnish react.

  Further, when an image is recorded by the ink jet method, unevenness is generated on the image surface due to the ejected ink in the halftone portion, and therefore, the gloss is further lowered than the non-image portion in combination with the above-described aggregation effect of the varnish component.

《Comparative example》
FIG. 8 is a diagram schematically showing the shape of the varnish plate according to Comparative Example 1. In the varnish plate 350 shown in FIG. 8, the lower side of the drawing is the convex portion 352 side that contacts the anilox roller 304 (see FIG. 4). The convex portion 352 of the varnish plate 350 is a single convex portion for uniformly applying the varnish to the image surface.

  FIG. 9 is a schematic view showing a state in which varnish is supplied to the varnish plate 350 shown in FIG. The varnish 360 transferred from the anilox roller 304 adheres to the convex portion 352 of the varnish plate 350.

  FIG. 10 is a diagram schematically showing the surface shape of the varnish transferred from the varnish plate 350 in the low image density portion of the image formed on the substrate. The base material 370 is one in which an undercoat liquid has been applied in advance before ink ejection. Reference numeral 380 in the figure indicates an ink todd formed by ink droplets. In the low image density portion, the ink dots 380 are sparsely arranged on the base material 370. The surface 361A of the varnish 361 is applied to the varnish 361 applied to the image surface of such a low image density portion by the ink dots 380 on the base material 370 and / or by the varnish component aggregated by reacting with the components of the undercoat liquid. The shape becomes rough and the gloss decreases.

  FIG. 11 is a diagram schematically showing the surface shape of the varnish transferred from the varnish plate 350 in the high image density portion of the image formed on the substrate. The base material 370 is one in which an undercoat liquid has been applied in advance before ink ejection. Reference numeral 382 in the drawing indicates an ink layer of a high image density portion formed by ink. In the high image density portion, ink dots are densely deposited on the base material 370 and the dots come into contact with each other to form the ink layer 382.

  The varnish 362 applied to the image surface of the ink layer 382 in such a high image density portion is less likely to cause aggregation of the varnish component due to the undercoat liquid, and the ink layer 382 itself is smooth, so the surface 362A of the varnish 362. The shape is smooth and glossy.

  When the varnish is uniformly applied to the image surface of the image including the low image density portion and the high image density portion using the varnish plate 350, the surface shape of the varnish in the low image density portion shown in FIG. Due to the difference in the surface shape of the varnish in the high image density portion shown in FIG.

<< Example of Varnish Plate Used in the Embodiment >>
FIG. 12 is a diagram schematically showing the shape of the varnish plate 400 applied to the high image density portion in the embodiment of the present invention. FIG. 13 is a schematic plan view showing an example of the pattern of the convex portions 402 and the concave portions 404 in the varnish plate 400 shown in FIG. The varnish plate 400 used in the embodiment has a concavo-convex structure in which a plurality of convex portions 402 are arranged in a lattice pattern. Each convex portion 402 has a quadrangular shape in plan view. The width Wp of the protrusions 402 arranged in a regular array pattern in a lattice shape is represented by “number of lines”. The width of the convex portion 402 may be rephrased as the interval between the convex portions 402. The number of lines can be expressed as the number of lines per inch. For example, 165 line per inch [line / inch] indicates a case where there are 165 patterns of convex portions 402 per inch. A concave portion 404 is formed between the convex portion 402 and the convex portion 402.

  In the concavo-convex pattern of the varnish plate 400, it is preferable that each of the plurality of convex portions 402 has an independent (isolated) polygonal or closed curve pattern shape, as in the square structure illustrated in FIG. It is particularly preferable that there is an edge at the boundary between the convex portion 402 and the concave portion 404. The area ratio of the convex portions 402 per unit area in the varnish plate 400 is referred to as a convex portion ratio. The convex portion ratio is synonymous with the halftone dot ratio of the varnish plate 400 which is a relief plate.

  12 and 13, the shape of the varnish plate 400 corresponding to the high image density portion is shown. However, the shape of the varnish plate corresponding to the low image density portion is 100% as in FIG. It may be a convex part. That is, the varnish plate 400 according to the embodiment has a concavo-convex structure in which the convexity ratio is varied according to the image density, and the convexity ratio of the region where the varnish is applied to the high image density portion is low. The convex portion ratio of the region where the varnish is applied differs from the image density portion.

  FIG. 14 is a developed plan view showing an example of the cell 342 of the anilox roller 304. The cell 342 of the anilox roller 304 is a recess that holds the varnish. FIG. 14 shows an example of the cell shape of the honeycomb pattern. The boundary between the cell 342 and the cell 342 is a convex portion 344 that is relatively convex with respect to the cell 342.

  The interval Wa between the cells 342 of the anilox roller 304 can also be expressed by “number of lines”. The number of lines of the anilox roller 304 is preferably larger than the number of lines of the varnish plate 400.

  FIG. 15 is a schematic diagram illustrating a state where the varnish plate 400 and the anilox roller 304 according to the embodiment are in contact with each other. A large number of cells 342 are regularly arranged on the surface of the anilox roller 304. When the varnish plate 400 contacts the anilox roller 304 holding the varnish 364, the varnish 364 is transferred from the anilox roller 304 to the uneven surface of the varnish plate 400. Since the varnish 364 has a relatively high viscosity, the varnish 364 wraps around and adheres not only to the convex portion 402 of the varnish plate 400 but also to the concave portion 404.

  FIG. 16 is a schematic diagram showing a state in which the varnish plate 400 is brought into contact with the base material 370 on which an image is recorded. The base material 370 is one in which an undercoat liquid has been applied in advance before ink ejection. Reference numeral 382 in the figure denotes an ink layer in a high image density portion.

  FIG. 17 is a schematic diagram showing a state in which the varnish is transferred from the varnish plate 400 to the base material 370. As shown in FIG. 17, the coating layer of the varnish 365 transferred from the varnish plate 400 to the base material 370 has a raised portion 366 corresponding to the edge of the concave portion 404 (see FIG. 16) of the varnish plate 400, resulting in a rough surface. .

  That is, when varnish is applied using the varnish plate 400, the varnish 365 is applied to the entire surface of the image, and the gloss reduction due to the uneven shape of the surface occurs, so the gloss of the high image density portion is reduced. To do. As a result, the gloss difference between the low image density portion and the high image density portion can be reduced while maintaining the film quality of the coating film of the varnish 365.

  The coating layer of the varnish 365 transferred from the varnish plate 400 to the image surface of the substrate 370 is caused by the uneven pattern of the varnish plate 400 having an uneven structure in which the uneven pattern is changed according to the image density of the image. Includes irregular shapes. The varnish plate 400 is an example of a “plate member”. The anilox roller 304 is an example of a “gloss imparting agent supply roller”.

<< Reference Example 1 >>
For reference, a state after varnish application by the technique described in Patent Document 1 will be described.

  FIG. 18 is a schematic diagram showing an example of a state in which varnish is applied to a low image density portion of an image recorded on a substrate by an image recording method that does not use an undercoat liquid. That is, the base material 371 shown in FIG. 18 is not provided with the undercoat liquid. The varnish 368 applied on the base material 371 in FIG. 18 is applied by the ink jet method by applying the technique described in Patent Document 1. In this case, aggregation of the varnish component due to the undercoat liquid does not occur, so that the surface shape of the varnish is hardly generated in the first place, and gloss reduction is not a problem.

  In addition, when the varnish is applied in dot units by the ink jet method which is a non-contact coating method, the coating film tends to be smooth because drying and aggregation of the varnish occur in dot units. In FIG. 18, the varnish surface 368 </ b> A is slightly roughened due to the influence of the ink dots 380 recorded on the base material 371.

<< Reference Example 2 >>
FIG. 19 is a schematic diagram showing an example of a state in which varnish is applied to a high image density portion of an image recorded on a substrate by applying the technique described in Patent Document 1. According to the technique described in Patent Document 1, in order to reduce the varnish recording rate (droplet ejection rate) for the high image density portion, the varnish 369 is sparsely applied to the image surface as shown in FIG. A part of the image portion is exposed on the surface. For this reason, the durability of the image area is inferior.

<< Evaluation experiment on improvement effect of gloss uniformity, surface shape of varnish surface, and durability >>
Next, the contents of an evaluation experiment examining the relationship between varnish application conditions, the effect of improving gloss uniformity, the surface shape of the varnish surface, and durability will be described.

<Experimental conditions>
The image recording apparatus, processing liquid, ink, varnish, paper, and varnish plate used in the experiment are as follows.

Image recording device: Jet Press720S manufactured by FUJIFILM Corporation
・ Processing liquid: C-FJ-CP manufactured by FUJIFILM Corporation ・ Ink: C-WP-Q manufactured by FUJIFILM Corporation ・ Water-based varnish: HYDLTH2012-R1 manufactured by DIC Graphix Corporation ・ Low-aggregation aqueous varnish: In addition, 1% by mass of AMP is added to “AMP”, which is 2-amino-2-methyl-1-propanol.

High leveling varnish: 5% by mass of IPA is added to the above “aqueous varnish”. “IPA” is isopropyl alcohol.

-Paper: New-DV 310GSM Hokuetsu Kishu Paper Co., Ltd. "GSM" is a unit representing the thickness of paper. The thickness of the paper, which is 1 gram per square meter, is 1 GSM. GSM is expressed as grams per square meter, or g / m ² .

-Varnish: DuPont Cyrel VSA
Thickness 1.14 mm, convex height 0.54 mm
<Experimental result>
FIG. 20 to FIG. 22 are tables summarizing the results of each condition, the effect of improving the gloss uniformity, the surface shape of the varnish surface, and the durability evaluation experiment. The experimental results shown in FIG. 20 are obtained by using “aqueous varnish” described in the column of experimental conditions. The experimental results shown in FIG. 21 are obtained using “low-aggregation aqueous varnish” described in the column of experimental conditions. The low agglomerated aqueous varnish is a varnish that hardly reacts with the components of the treatment liquid. The experimental results shown in FIG. 22 are obtained by using the “high leveling varnish” described in the column of experimental conditions. Each of the “aqueous varnish”, “low-aggregating aqueous varnish”, and “high leveling varnish” used in the experiment corresponds to an example of “a gloss imparting agent that changes its performance by reacting with an image quality improver”.

  The items of each condition shown in FIGS. 20 to 22 are as follows.

  The “number of anilox rollers” is the number of wires of the anilox roller that supplies varnish to the varnish plate. The “number of varnish plates” is the number of varnish plates used for varnish application.

  The “halftone dot shape” means a planar view shape of the convex portion of the varnish plate. “Square” refers to the square halftone dot shape illustrated in FIG. “Circular” refers to a circular halftone dot shape.

  The “halftone dot ratio” represents the ratio of convex portions per unit area in the varnish plate, and indicates the convex portion ratio. Different halftone dot ratios can be set according to the image density of the image recorded on the paper. Changing the halftone dot ratio of the varnish plate according to the image density corresponds to making the uneven structure different according to the image density.

  The distinction between “non-image portion”, “low image density portion” and “high image density portion” is defined as follows, for example.

  “Non-image portion” refers to an image region having a digital image density of 0% or more and less than 20%.

  “Low image density portion” refers to an image area having a digital image density of 20% or more and less than 60%.

  “High image density portion” refers to an image area having a digital image density of 60% or more and 100% or less.

  However, these definitions may vary depending on the materials and system conditions such as the ink and substrate used, the treatment liquid, and the varnish. Also, instead of setting the halftone dot ratio in three stages of “non-image area”, “low image density area” and “high image density area”, the halftone dot ratio of the varnish plate is set according to the calibration curve. May be.

  Note that 20%, which is the boundary between the non-image portion and the low image density portion according to the above definition, may be included in either the non-image portion or the low image density portion, and 20% is included in the non-image portion. May be. Further, 60%, which is the boundary between the low image density portion and the high image density portion, may be included in either the low resolution portion or the high image density portion, and 60% may be included in the low image density portion. Good.

  An image density of 0% corresponds to a “minimum image density”. An image density of 100% corresponds to a “maximum image density”. Of the image density range from the minimum image density to the maximum image density, the high image density portion and the low image density portion are defined according to the characteristics of the gloss performance as described in FIG. The high image density portion is an image portion having a relatively high image density in the image density range from the minimum image density to the maximum image density, and is a region where gloss is lowered. The low image density portion is an image portion having an image density that is relatively lower than the high image density portion in the image density range from the minimum image density to the maximum image density. This is the area where

<Evaluation method>
[Evaluation method for improving gloss uniformity between image densities]
The method for evaluating the effect of improving the gloss uniformity between image densities is as follows.

  Using a micro-TRI gloss manufactured by BYK, the 60 ° glossiness of an image density of 0 to 100% (5% increments) of a black single color was measured, and the difference between the maximum gloss value and the minimum gloss value was calculated. The difference between the gloss difference value calculated from the sample under each condition and the gloss difference calculated from Comparative Example 1 was calculated to evaluate the gloss uniformity improving effect. In Comparative Example 1, a varnish is uniformly applied to the entire surface of an image. The evaluation criteria were the following four stages.

AA: Significant improvement effect (difference from gloss difference of Comparative Example 1 is 5 or more)
A: Improvement effect (difference from gloss difference of Comparative Example 1 is 1 or more and less than 5)
B: Slight improvement effect (difference from gloss difference of Comparative Example 1 is greater than 0 and less than 1)
C: No improvement effect
[Method for evaluating surface condition of varnish surface]
If each pattern of the convex portions of the varnish plate is too large, an array pattern of convex portions (for example, a lattice shape) is visually recognized on the surface of the varnish transferred from the varnish plate, and gloss unevenness is generated. The planar evaluation is an evaluation of whether or not gloss unevenness reflecting the pattern of the convex portions of the varnish plate as described above is visually recognized on the varnish surface. The method for evaluating the surface state of the varnish surface is as follows.

  The sample after varnish application was visually observed at an angle of 60 ° from a location 30 centimeters [cm] away. The difference from Comparative Example 1 was judged regarding the uneven glossiness within the same image density. The evaluation criteria were the following four stages.

A: No difference at all A: There is a slight difference, but acceptable B: There is a difference, but acceptable C: There is a significant difference, non-acceptable [Durability Evaluation Method]
Evaluation of durability may be paraphrased as evaluation of abrasion resistance of the image area. When the image surface is covered with a varnish, the image surface is protected by the varnish, and durability is increased. On the other hand, if there is no varnish on part or all of the image surface and part or all of the ink on the image surface is exposed, the durability is lowered.

  The evaluation method of the durability of the image area is as follows.

  A cotton swab was impregnated with ethanol, and the surface of the sample was rubbed 10 times with the cotton swab to confirm damage to the surface. The difference between the damage of each sample and the damage of Comparative Example 1 was judged. The evaluation criteria were the following four stages.

A: No difference at all A: There is a slight difference, but acceptable B: There is a difference, but acceptable C: There is a significant difference, non-acceptable <Explanation of experimental results shown in FIG. 20>
In the table of FIG. 20, Comparative Example 1 with sample number 1 is a solid varnish applied uniformly over the entire image surface. As described with reference to FIG. 5, the comparative example 1 has a large gloss difference between image areas having different image densities and poor gloss uniformity.

  In Comparative Example 2 of Sample No. 2, the varnish was uniformly applied to the non-image area and the low image density area, and the varnish was not applied to the high image density area. Compared to Comparative Example 1, Comparative Example 2 improves gloss uniformity but deteriorates durability.

  Sample numbers 3 through 9 are examples of the present invention. When a varnish was applied to the image surface under the conditions shown in Sample No. 3, good results were obtained for the evaluation items of gloss uniformity improvement effect, surface condition, and durability.

  Sample numbers 4 and 5 were obtained by reducing the number of varnished plates from the condition of sample number 3. When the number of lines of the varnish plate is reduced, the pattern of each convex portion is increased, so that the surface shape tends to be lowered.

  Sample No. 6 is obtained by lowering the dot ratio in the high image density portion as compared with the condition of Sample No. 3. When the halftone dot ratio was lowered to 25%, the surface shape was lowered as compared with Sample No. 3. When the halftone dot ratio was lowered to 25%, the varnish raised portions corresponding to the edges of the recesses described in FIG. 17 were partially missing. This is considered to be because the varnish does not sufficiently adhere to some of the recesses in the varnish plate.

  Sample number 7 is obtained by increasing the number of lines of the varnish plate as compared with the condition of sample number 3. When the number of lines of the varnish plate was increased to 120 (line / inch), the surface shape was lowered as compared with Sample No. 3. This is due to the occurrence of the dipping phenomenon. The dipping phenomenon is a phenomenon in which the convex part of the varnish plate is buried in the cell of the anilox roller. The dipping phenomenon occurs on some convex parts of the varnish plate, and the dipping phenomenon does not occur on other convex parts, resulting in an unstable varnish supply amount, resulting in gloss Unevenness may occur.

  From the viewpoint of avoiding the dipping phenomenon, it is preferable that the number of varnish plates is smaller than the number of wires of the anilox roller and the number of varnish plates is not too close to the number of wires of the anilox roller.

  Sample number 8 is obtained by increasing the number of lines of the anilox roller as compared with the condition of sample number 3. When the number of lines of the anilox roller is increased, the coating amount of the varnish decreases as a whole, so that the gloss tends to decrease as a whole.

  Sample No. 9 is obtained by changing the halftone dot shape of the varnish plate to a circular circular as compared with the condition of Sample No. 3. When the halftone dot shape is a circular structure, the adhesion of the varnish to the edge of the recess becomes unstable as compared with the square structure. As a result, the sample number 9 has a lower evaluation than the sample number 3 with respect to the gloss uniformity and the surface shape. The halftone dot shape is preferably a square structure.

<Description of Experimental Results Shown in FIG. 21>
In the table of FIG. 21, the comparative example 1 of the sample number 1 is the same as the comparative example 1 of the sample number 1 of FIG.

  Sample number 10 is an example of the present invention. When a varnish was applied to the image surface under the conditions shown in Sample No. 10, good results were obtained in the evaluation items of gloss uniformity improvement effect, surface condition, and durability.

<Description of Experimental Results Shown in FIG. 22>
In the table of FIG. 22, the comparative example 1 of the sample number 1 is the same as the comparative example 1 of the sample number 1 of FIG.

  Sample numbers 11-12 are examples of the present invention. When varnish was applied to the image surface under the conditions shown in Sample Nos. 11 to 12, good results were obtained in the evaluation items of gloss uniformity improvement effect, surface condition, and durability.

<Matters grasped from experimental results>
At least the following matters are grasped from the experimental results of FIGS.

  (1) It is preferable that the varnish plate has a concavo-convex structure in which the concavo-convex pattern is changed according to the image density. When using a varnish that has a property that the glossiness decreases by reacting with the components of the processing solution, the convexity ratio (halftone dot ratio) in the varnish area corresponding to the high image density portion is reduced. It is preferable to make it smaller than the convex portion ratio (halftone dot ratio) in the varnish plate region corresponding to.

  As a result, the surface shape of the varnish applied to the high image density portion becomes rough, the gloss of the high image density portion approaches that of the low image density portion, and the gloss difference between the low image density portion and the high image density portion becomes small. . In addition, since the entire surface of the image portion is covered with varnish, durability is also ensured.

  In order to vary the convex portion ratio of the varnish according to the image density, the image density is evaluated based on the image data to be printed, the convex portion ratio is set, and the varnish plate is manufactured based on the setting. .

  (2) The number of lines in the concavo-convex structure pattern in the varnish plate is preferably larger than the number of lines in the anilox roller. By satisfying these conditions and selecting an appropriate line number combination, the dipping phenomenon in which the convex portion of the varnish plate is buried in the cell of the anilox roller can be suppressed, and the surface caused by the occurrence or non-occurrence of dipping The deterioration of the state can be suppressed.

  (3) The halftone dot shape of the varnish plate, that is, the uneven pattern of the varnish plate preferably has a square structure. Moreover, it is preferable that the convex part rate of a varnish plate is 50% or more. A configuration in which the uneven pattern of the varnish plate has a square structure and the convex portion ratio is 50% or more is more preferable.

  (4) There is a difference in reactivity with the treatment liquid depending on the type of varnish, and the degree of gloss reduction due to the presence or absence of the treatment liquid is different. Therefore, it is preferable to change the convex portion ratio of the varnish according to the image density from the low image density portion to the high image density portion depending on the type of varnish used. Even in the case of using a low-aggregation aqueous varnish or a high leveling varnish that is difficult to agglomerate with an image quality improver, it can be dealt with by setting an appropriate convex portion ratio.

<Configuration example of offline varnish coater>
In the above embodiment, the varnish application device is incorporated in the image recording apparatus and applied inline. However, an off-line varnish application apparatus separate from the image recording apparatus may be used. FIG. 23 is a configuration diagram showing an embodiment of an offline type varnish coating apparatus.

  In FIG. 23, elements common to the configuration of the image recording apparatus 10 shown in FIG. 1 are assigned the same reference numerals, and descriptions thereof are omitted. A varnish application apparatus 500 illustrated in FIG. 23 includes a paper feed unit 512 that feeds the paper P, a varnish application unit 22, a varnish post-processing unit 24, and a paper discharge unit 26. The paper feeding unit 512 includes a paper feeding table 530, a paper feeding device 532, a feeder board 536, and a paper feeding drum 538, similarly to the configuration of the paper feeding unit 12 of the image recording apparatus 10 described with reference to FIG. . A sheet P on which an image is recorded using processing liquid and ink is stacked on the sheet feeding table 530. The paper feed device 532 feeds the paper P from the paper feed tray 530 one by one to the paper feed roller pair 534. The paper P is sent from the feeder board 536 to the varnish drum 65 via the paper supply drum 538. The paper supply drum 538 includes a gripper 538A.

  In the varnish coating apparatus 500, the paper P on which an image has been recorded is directly fed from the paper feeding unit 512 to the varnish coating unit 22. The fed paper P is applied with varnish by the varnish application unit 22, subjected to predetermined post-processing by the varnish post-processing unit 24, and discharged by the paper discharge unit 26.

<< System configuration example of an image recording apparatus in which offline varnish application is performed >>
FIG. 24 is an overall configuration diagram showing an outline of a system configuration of an image recording apparatus in which offline varnish application is performed. An image recording apparatus 600 shown in FIG. 24 is an ink jet printing system including an ink jet recording apparatus 10A and a varnish coating apparatus 500. The image recording apparatus 600 illustrated in FIG. 24 is an example of “Mode 2-1”.

  The ink jet recording apparatus 10A shown in FIG. 24 differs from the image recording apparatus 10 shown in FIG. 24, elements that are the same as or similar to those shown in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  The operations of the inkjet recording apparatus 10A and the varnish coating apparatus 500 shown in FIG. 24 may be controlled separately. In the image recording apparatus 600, an image recording process and a varnish coating process are separately performed, and an offline varnish coating in which each process is performed independently is applied. When offline varnish application is performed, the paper P on which an image has been recorded by the ink jet recording apparatus 10A is once accumulated on the paper discharge tray 76A of the paper discharge unit 26A of the ink jet recording apparatus 10A.

  The sheet bundle Px taken out from the paper discharge tray 76A of the ink jet recording apparatus 10A is set on the paper feed tray 530 of the varnish coating apparatus 500. The sheet bundle Px is coated with an aqueous varnish using the varnish coating apparatus 500. The process of transferring the sheet bundle Px from the ink jet recording apparatus 10A to the varnish application apparatus 500 may be performed manually by an operator such as carrying the sheet bundle Px, or may be automated using a conveyor or a robot (not shown). May be.

<< System configuration example of an image recording apparatus in which online varnish application is performed >>
FIG. 25 is an overall configuration diagram showing an outline of a system configuration of an image recording apparatus in which online varnish application is performed. An image recording apparatus 602 shown in FIG. 25 is an ink jet printing system including an ink jet recording apparatus 10A, a paper transport apparatus 610, and a varnish coating apparatus 500. An image recording apparatus 602 shown in FIG. 25 is an example of an apparatus configuration classified as “mode 2-2”.

  The configurations of the ink jet recording apparatus 10A and the varnish coating apparatus 500 are the same as those described with reference to FIG. In the image recording apparatus 602 shown in FIG. 25, the paper discharge table 76A of the inkjet recording apparatus 10A and the paper supply table 530 of the varnish application device 500 are omitted, compared with the configuration described in FIG. The difference is that a sheet transfer device 610 is provided instead of 76A and the sheet feed table 530.

  An image recording apparatus 602 shown in FIG. 25 has a configuration in which a sheet transfer device 610 is connected to the paper discharge unit of the inkjet recording apparatus 10A, and the sheet P is automatically supplied from the sheet transfer device 610 to the varnish application device 500. ing. In FIG. 25, reference numerals are omitted for the components of the ink jet recording apparatus 10 </ b> A and the components of the varnish coating apparatus 500.

  The sheet transfer device 610 includes a conveyor 612. The conveyor 612 receives the paper P discharged from the paper discharge unit of the ink jet recording apparatus 10 </ b> A, conveys the paper P along the conveyance path of the paper P, and delivers it to the paper supply unit 512 of the varnish application apparatus 500.

  The paper feed unit 512 of the varnish application apparatus 500 receives the paper P from the conveyor 612 and sequentially feeds the paper P to the varnish application unit 22. The collection of the paper P is performed by the paper discharge unit 26 of the varnish application apparatus 500. The sheets P are stacked and collected in a bundle on the sheet discharge tray 76 of the varnish application apparatus 500.

  When printing is performed, the ink jet recording apparatus 10A and the varnish coating apparatus 500 operate in conjunction with each other. When it is not necessary to apply the varnish, the varnish application function and the varnish post-processing function of the varnish application apparatus 500 may be stopped.

  Online varnishing is a form in which image recording and varnishing are continuously performed as a series of processes. The system shown in FIG. 25 performs on-line varnish application by connecting an inkjet recording apparatus 10A, which is an apparatus for recording an image, and a varnish application apparatus 500 that performs varnish application in series. According to the image recording sparse 602 shown in FIG. 25, continuous processing is possible by feeding the paper P discharged from the ink jet recording apparatus 10A to the varnish coating apparatus 500 as it is.

<About treatment liquid>
The treatment liquid used in the embodiment includes at least an aggregating agent that aggregates the components in the ink composition of the color ink, and may be configured using other components as necessary. By using the treatment liquid together with the ink composition, it is possible to increase the speed of ink jet recording, and an image excellent in reproducibility of high density and resolution, for example, fine lines and fine portions can be obtained even at high speed recording.

  The aggregating agent may be a compound capable of changing the pH of the ink composition, a polyvalent metal salt, or polyallylamines. In the present invention, from the viewpoint of cohesiveness of the ink composition, a compound capable of changing the pH of the ink composition is preferable, and a compound capable of lowering the pH of the ink composition is more preferable.

  As the flocculant used in the present embodiment, an acidic substance having high water solubility is preferable, and an organic acid is preferable from the viewpoint of increasing the aggregation property and fixing the whole ink, and a divalent or higher organic acid is more preferable. Above-mentioned trivalent or less acidic substances are particularly preferred. As the divalent or higher organic acid, an organic acid having a first pKa (acid dissociation constant) of 3.5 or less is preferable, and an organic acid of 3.0 or less is more preferable. Specifically, for example, phosphoric acid, oxalic acid, malonic acid, citric acid, derivatives of these compounds, salts thereof, and the like are preferable. A flocculant can be used individually by 1 type or in mixture of 2 or more types.

  The content of the flocculant for aggregating the ink composition in the treatment liquid is preferably 1 to 50% by mass, more preferably 3 to 45% by mass, and still more preferably 5 to 40% by mass.

  The treatment liquid can further contain other additives as other components within a range not impairing the intended aggregation effect. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, anti-foaming agents. Well-known additives, such as a foaming agent, a viscosity modifier, a dispersing agent, a dispersion stabilizer, a rust preventive agent, a chelating agent, are mentioned.

About varnish
As the varnish, a general aqueous varnish used in the printing field can be used. In the present invention, the reaction of the varnish component with the image quality improver changes the performance of the varnish, which is one of the elements of the problem solving principle. In the practice of the present invention, various types of aqueous varnishes having the property that the performance of the varnish after coating changes depending on the presence or absence of an image quality improver can be used.

  Many common aqueous varnishes contain an acrylic polymer. The acrylic polymer reacts with the acid component and aggregates. In the aqueous varnish containing an acrylic polymer, the surface shape of the varnish surface changes depending on the presence or absence of an image quality improver containing an acid component, that is, the gloss performance changes.

<Discharge method of inkjet head>
An ejector of an inkjet head includes a nozzle that discharges liquid, a pressure chamber that communicates with the nozzle, and a discharge energy generating element that applies discharge energy to the liquid in the pressure chamber. With respect to the ejection method for ejecting liquid droplets from the nozzle of the ejector, the means for generating the ejection energy is not limited to the piezoelectric element, and various ejection energy generating elements such as a heating element and an electrostatic actuator can be applied. For example, it is possible to employ a method in which droplets are ejected using the pressure of film boiling caused by heating of a liquid by a heating element. Corresponding ejection energy generating elements are provided in the flow path structure according to the ejection method of the inkjet head.

<About paper>
“Paper” is a medium used for image recording, and is included in the concept of “base material”. The term “paper” is a generic term for a variety of terms such as recording paper, printing paper, printing medium, printing medium, printing medium, image forming medium, image forming medium, image receiving medium, and discharged medium. The material, shape, and the like of the paper are not particularly limited, and various sheet bodies can be used regardless of sealing paper, resin sheet, film, cloth, nonwoven fabric, and other materials and shapes. The sheet is not limited to a sheet medium, and may be a continuous medium such as continuous paper. Further, the sheet of paper is not limited to a cut sheet that has been preliminarily adjusted to a predetermined size, and may be obtained by cutting from a continuous medium to a predetermined size as needed.

<< Modification 1 >>
In the above-described embodiment, the single-pass inkjet recording apparatus has been described as an example of the image recording apparatus. However, the present invention can be applied to various types of image recording apparatuses. For example, the present invention can also be applied to a multi-scan ink jet recording apparatus that forms an image by reciprocating a short ink jet head. Further, the means for recording an image on the substrate in the practice of the present invention is not limited to the ink jet recording apparatus, and a plate type printing machine such as an offset printing machine may be used.

<< Modification 2 >>
The image recording method according to the above-described embodiment is an example including the step of applying the treatment liquid to the paper P. However, a paper to which an image quality improver corresponding to the component of the treatment liquid is previously applied may be used. In this case, the process of applying the treatment liquid to the paper P is not necessary.

<< Modification 3 >>
In the above-described embodiment, the form using the flexographic printing method has been described as an example of the contact-type coating method, but a gravure printing method may be employed instead of the flexographic printing method. In the gravure printing method, an intaglio as a plate member is used.

《Terminology》
The term “image recording apparatus” is synonymous with terms such as a printing press, a printer, a printing apparatus, a printing apparatus, an image forming apparatus, an image output apparatus, or a drawing apparatus.

  “Image” is to be interpreted in a broad sense, and includes a color image, a monochrome image, a single color image, a gradation image, a uniform density (solid) image, and the like. The “image” is not limited to a photographic image, but is used as a comprehensive term including a pattern, a character, a symbol, a line drawing, a mosaic pattern, a color painting pattern, other various patterns, or an appropriate combination thereof.

  “Recording” an image includes the concept of terms such as image formation, printing, printing, drawing, and printing. “Printing” includes the concept of digital printing based on digital data.

  In the present specification, the term “orthogonal” or “perpendicular” refers to a case of intersecting at an angle of substantially 90 ° in an aspect of intersecting at an angle of less than 90 ° or greater than 90 °. The mode which produces the same operation effect as is included.

  The “image recording method” according to the present invention is understood as a manufacturing method for manufacturing a printed matter.

<< Combination of Embodiments and Modifications >>
The matters described in the above-described embodiments and the modifications can be used in appropriate combinations, and some of the matters can be replaced.

  In the embodiment of the present invention described above, the configuration requirements can be changed, added, or deleted as appropriate without departing from the spirit of the present invention. The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the related fields within the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 10 Image recording apparatus 10A Inkjet recording device 12 Paper supply part 14 Processing liquid application part 16 Processing liquid drying part 18 Image recording part 20 Image post-processing part 20A Ink drying part 20B Ink UV hardening part 22 Varnish application part 24 Varnish post-processing part 24B Varnish drying unit 26 Paper discharge unit 26A Paper discharge unit 30 Paper feed base 32 Paper feed device 34 Paper feed roller pair 36 Feeder board 38 Paper feed drum 38A Gripper 42 Processing liquid drum 42A Gripper 44 Processing liquid coating device 44A Processing liquid coating roller 44B Processing liquid container 44C Processing liquid supply roller 46 Processing liquid drying drum 46A Gripper 48 Paper transport guide 50 Processing liquid dryer 52 Image recording drum 52A Gripper 54 Paper pressing rollers 56C, 56M, 56Y, 56K Inkjet head 58 Inline sensor 64 For image post-processing Chain gripper 6 A Chain 64B Gripper 64C First sprocket 64D Second sprocket 65 Varnish drum 65A Gripper 66 Varnish post-treatment chain gripper 66A Chain 66B Gripper 66C Third sprocket 66D Fourth sprocket 67 Inclined conveyance path 68 Ink dryer 69 UV irradiation device 72 First guide Plate 74 Varnish dryer 75 Second guide plate 76, 76A Discharge stand 80 Varnish application unit 82 Varnish application roller 84 Varnish supply roller 86 Varnish chamber 200 System controller 202 Communication unit 204 Image memory 210 Transport control unit 212 Paper feed control unit 214 Processing liquid Application control unit 216 Treatment liquid drying control unit 218 Image recording control unit 220 Image post-processing control unit 220A Ink drying control unit 220B Ink UV curing control unit 222 Varnish application control 224 Varnish drying control unit 226 Discharge control unit 230 Operation unit 232 Display unit 250 Transport system 260 Host computer 300 Varnish coating device 302 Doctor chamber 304 Anilox roller 306 Plate cylinder 308 Impression cylinder 310 Plate 312 Convex part 314 Concave part 320 Container 322 Doctor Blade 330 Varnish 342 Cell 344 Projection 350 Varnish plate 352 Projection 360, 361 Varnish 361A Surface 362 Varnish 362A Surface 364, 365 Varnish 366 Partial 368 Varnish 368A Varnish surface 369 Varnish 370, 371 Base material 380 Ink dot 382 Ink layer 400 Varnish Plate 402 Convex part 404 Concave part 500 Varnish coating device 512 Paper feed part 530 Paper feed base 532 Paper feed device 536 Feeder board 538 Paper feed drum 600, 602 Image recording device 610 Paper transfer device 612 Bear P Paper Px sheet bundle S1~S9: step of the image recording method

Claims (14)

An image recording process for recording an image on a substrate provided with an image quality improver;
A gloss-imparting agent coating step of applying a gloss-imparting agent to the image surface of the base material on which the image is recorded by the image recording step by a contact-type coating method,
The gloss-imparting agent is a substance that changes its performance by reacting with the image quality improver,
The gloss imparting agent application step is an image recording method in which the gloss imparting agent is imparted to the image surface using a plate member having a concavo-convex structure in which a concavo-convex pattern is varied according to the image density of the image. Including an image quality improver application step of applying an image quality improver to the substrate,
The image recording method according to claim 1, wherein the image recording step records an image on the base material to which the image quality improving agent has been applied in the image quality improving agent applying step.   The image recording method according to claim 1, wherein the contact-type coating method is a flexographic printing method using a relief plate as the plate member.   The image according to any one of claims 1 to 3, wherein the plate member has a concavo-convex structure in which a convexity ratio indicating an area ratio of the convexity per unit area is varied according to an image density of the image. Recording method. The image includes a high image density portion that is an image portion having a relatively high image density in an image density range from a minimum image density to a maximum image density, and a low image density portion that is an image portion having a relatively low image density. And including
The image recording method according to claim 4, wherein the plate member has a convex portion ratio with respect to the high image density portion that is smaller than the convex portion ratio with respect to the low image density portion.   The image recording method according to claim 5, wherein the convex portion ratio with respect to the high image density portion is 50% or more and less than 100%.   The image recording method according to claim 5 or 6, wherein the convex portion ratio of the high image density portion is changed from the low image density portion according to the type of the gloss imparting agent to be used.   The image recording according to any one of claims 1 to 7, wherein the number of lines of the uneven pattern of the plate member is larger than the number of lines of a gloss imparting agent supply roller that supplies the gloss imparting agent to the plate member. Method.   The image recording method according to claim 1, wherein the pattern of the convex portions of the plate member has a square structure having a quadrangle in a plan view. The image quality improving agent includes an aggregating agent that aggregates components in the ink,
The image recording method according to claim 1, wherein the gloss imparting agent is an aqueous varnish. The image quality improver contains an acidic substance,
The image recording method according to claim 1, wherein the gloss imparting agent contains an acrylic polymer.   The image recording method according to claim 1, wherein a coating layer of the gloss imparting agent that covers the entire surface of the image is formed by the gloss imparting agent coating step.   The image recording method according to any one of claims 1 to 12, wherein the image recording step records an image on the substrate by an inkjet method. An image recording unit for recording an image on a base material provided with an image quality improver;
A gloss-imparting agent application unit that applies a gloss-imparting agent to the image surface of the base material on which the image is recorded by the image recording unit by a contact-type application method,
The gloss-imparting agent is a substance that changes its performance by reacting with the image quality improver,
The gloss-imparting agent applying unit applies the gloss-imparting agent to the image surface using a plate member having a concavo-convex structure in which a concavo-convex pattern is varied according to the image density of the image.