Image formation device, and image formation method

Abstract

To improve fixability of an image to a recording medium.SOLUTION: An image formation device 1 includes an intermediate transfer body 10, a primary coating liquid discharge part 11 for coating a primary coating liquid 50 to the intermediate transfer body 10, a solvent 52, an ink jet head 12 for coating ink 51 containing a resin 53 dissolved in the solvent 52 and a coloring material onto the intermediate transfer body 10, and a heater 13 for heating the intermediate transfer body 10 after the primary coating liquid 50 and the ink 51 have been coated thereto, wherein the heater 13 heats the intermediate transfer body 10 in which the primary coating liquid 50 is mixed with the solvent 52, and the resin 53 is precipitated to the side of a gas-liquid interface on the intermediate transfer body 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus and an image forming method. [Background technology]

[0002] 2. Description of the Related Art In an image forming apparatus that applies ink to form an image on a recording medium, a technique is known in which a solvent and a resin or coloring material contained in the ink are applied to the recording medium or the like, and then the solvent is removed.

[0003] For example, in Patent Document 1 (Japanese Patent No. 6295841), a first solvent is applied to a recording medium, and then ink is applied to the recording medium. The first solvent and the second solvent contained in the ink are mixed on the recording medium, and the resin contained in the ink precipitates. Then, an absorbing roller is pressed against the recording medium to absorb the solvent on the recording medium and remove it from the recording medium. Summary of the Invention [Problem to be solved by the invention]

[0004] The method of Patent Document 1 has a problem in that the deposited resin does not have sufficient fixability to a recording medium.

[0005] In view of the above circumstances, an object of the present invention is to improve the fixability of an image onto a recording medium. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides an image forming apparatus comprising an intermediate transfer body, a first application member that applies a pre-coating liquid to the intermediate transfer body, a second application member that applies an ink containing a solvent and a resin and colorant dissolved in the solvent to the intermediate transfer body, and a heating member that heats the intermediate transfer body after the pre-coating liquid and the ink have been applied, wherein the heating member heats the intermediate transfer body on which the pre-coating liquid has mixed with the solvent and the resin has precipitated onto the air-liquid interface side on the intermediate transfer body. Effect of the Invention

[0007] In the present invention, the fixation of an image onto a recording medium can be improved. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] 1 is a diagram showing a state in which the ink solvent is mixed with the pre-coating liquid and a resin is precipitated. FIG. [Diagram 3] FIG. 2 is a diagram showing the SP values ​​and solubility ranges of pre-coating liquids, solvents, and resins. [Figure 4] FIG. 13 is a diagram showing an evaluation test for evaluating the ratio of a solvent miscible in a pre-coating liquid, in which (a) shows the state before mixing, and (b) shows the state after mixing. [Diagram 5] FIG. 13 is a schematic diagram illustrating a modified example of the image forming apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and the duplicated description will be appropriately simplified or omitted.

[0010] As shown in FIG. 1, the image forming apparatus 1 of this embodiment has an intermediate transfer body 10, a pre-coating liquid ejection member 11 as a first coating member, an inkjet head 12 as a second coating member, a heater 13 as a heating member, conveying rollers 14 and 15, a pressure roller 16, a transfer roller 17, and a conveying belt 18.

[0011] The intermediate transfer body 10 in this embodiment is an intermediate transfer belt. The intermediate transfer body 10 is stretched by transport rollers 14 and 15 and a pressure roller 16, and can rotate in the direction of arrow A in Fig. 1. The direction of arrow A is also called the rotation direction of the intermediate transfer body 10.

[0012] The pre-coating liquid discharge member 11 applies the pre-coating liquid onto the intermediate transfer body 10. The portion of the intermediate transfer body 10 facing the pre-coating liquid discharge member 11 is the application position where the intermediate transfer body 10 is applied with the pre-coating liquid. The pre-coating liquid discharge member 11 of this embodiment has a similar configuration to the inkjet head 12, except that the liquid discharged is the pre-coating liquid. However, the first application member may be an application roller that applies the pre-coating liquid.

[0013] The inkjet head 12 ejects ink and applies the ink onto the intermediate transfer body 10. The portion of the intermediate transfer body 10 facing the inkjet head 12 is the application position where the intermediate transfer body 10 is applied with ink.

[0014] The pressure roller 16 is pressed against the transfer roller 17 via the intermediate transfer body 10 and the conveyor belt 18 to form a transfer nip N. The pressure roller 16 presses the intermediate transfer body 10 against the recording medium on the conveyor belt 18. The conveyor belt 18 conveys the recording medium P to the transfer nip N. In the transfer nip N, an image is transferred from the intermediate transfer body 10 to the recording medium P. In other words, the transfer nip N is a transfer position where the image is transferred to the recording medium P. The recording medium P in this embodiment is paper.

[0015] The heater 13 heats the surface of the intermediate transfer body 10. The heater 13 heats the intermediate transfer body 10 downstream of the application position of the pre-coating liquid or ink and upstream of the transfer position in the rotation direction of the intermediate transfer body 10.

[0016] Hereinafter, a method of forming an image on a recording medium P in the image forming apparatus 1 of this embodiment will be described with reference to Fig. 1 and Figs. 2(a) to (c). Figs. 2(a) to (c) are diagrams for explaining how a resin in an ink precipitates on an intermediate transfer body 10.

[0017] When an image forming operation is started, first, a pre-coating liquid is applied from a pre-coating liquid discharge member 11 to the intermediate transfer body 10. The portion of the intermediate transfer body 10 on which the pre-coating liquid has been applied moves to a position facing the inkjet head 12 as the intermediate transfer body 10 rotates in the direction of arrow A. Then, as shown in Fig. 2(a), the inkjet head discharges ink 51 onto the surface of the intermediate transfer body 10 on which the pre-coating liquid 50 has been applied. The ink 51 contains a solvent 52, a resin 53 that dissolves in the solvent 52, and a color material (pigment).

[0018] The solvent 52 is miscible with the first coating liquid 50. As shown in FIG. 2(b), when the ink 51 is applied onto the first coating liquid 50, the solvent 52 of the ink 51 moves toward the first coating liquid 50, and the solvent 52 and the first coating liquid 50 are mixed together. At that time, the resin 53 in the ink 51 does not dissolve in the first coating liquid 50, so that the resin 53 and the coloring material are difficult to move toward the first coating liquid 50. In addition, the resin 53 has a smaller density than the first coating liquid 50 and the solvent 52. For this reason, as shown in FIG. 2(c), the resin 53 containing the coloring material is precipitated on the gas-liquid interface side (upper side of FIG. 2) on the intermediate transfer body 10. As described above, in this embodiment, the solvent and the first coating liquid unnecessary for image formation are moved toward the intermediate transfer body 10, and the resin 53 can be precipitated on the gas-liquid interface side without heating.

[0019] 1, as the intermediate transfer body 10 rotates, the deposited resin is heated by the heater 13. This softens the resin and makes it sticky. The heater 13 heats the resin 53 to a temperature equal to or higher than the glass transition point of the resin 53, for example.

[0020] Then, as the intermediate transfer body 10 rotates, the portion of the intermediate transfer body 10 that has been heated by the heater 13 moves to the transfer position. At this timing, the recording medium P is transported to the transfer position. The intermediate transfer body 10 is pressed against the recording medium P by the transfer nip N, and the image on the intermediate transfer body 10 is transferred to the recording medium P. This completes the transfer of the image to the recording medium P.

[0021] As described above, in this embodiment, the resin 53 is efficiently heated by preliminarily precipitating the resin 53 on the air-liquid interface side of the intermediate transfer body 10. This makes it easier to soften the resin 53, and makes it possible to impart adhesiveness to the resin 53. By transferring an image to the recording medium P in this state, the fixability of the image to the recording medium P can be improved.

[0022] FIG. 3 shows the SP values ​​(solubility parameters) of pre-coating liquids, solvents, and resins, and the range of SP values ​​in which each can be dissolved. As shown in FIG. 3, the SP value of the solvent 52 is a value between the SP value of the previous coating liquid 50 and the SP value of the resin 53. The SP values ​​of the solvent 52 and the previous coating liquid 50 in the ink are close to each other, their solubility ranges overlap, and the solvent 52 and the previous coating liquid 50 are miscible. The SP value of the solvent 52 is close to that of the resin 53, their solubility ranges overlap, and the resin 53 dissolves in the solvent 52. On the other hand, the SP values ​​of the resin 53 and the previous coating liquid 50 are far apart, their solubility ranges do not overlap, and the resin 53 does not dissolve in the previous coating liquid 50. Specifically, in the example of FIG. 3, the lower limit of the solubility range of the resin 53 is set to be smaller than the upper limit of the solubility range of the solvent 52 and larger than the upper limit of the solubility range of the previous coating liquid 50. In addition, the density of the resin 53 in the ink is set to be smaller than that of the solvent 52 and the previous coating liquid 50 in the ink 51, so that when the previous coating liquid 50 and the ink 51 are applied onto the intermediate transfer body 10, the resin 53 moves to the air-liquid interface and precipitates. Also, the speed at which the previous coating liquid 50 is mixed with the solvent 52 is greater than the speed at which the resin 53 dissolves in the solvent 52. The lower limit of the solubility range of the solvent 52 is set to be smaller than the upper limit of the previous coating liquid 50, and the solvent 52 is miscible with the previous coating liquid 50.

[0023] Next, the evaluation test to confirm the mixing of the solvent in the ink and the pre-coating liquid will be explained with reference to Figures 4(a) and (b). Figure 4(a) shows the state before mixing, and Figure 4(b) shows the state after mixing.

[0024] As shown in FIG. 4(a), first, a predetermined amount of the pre-coating liquid 50 is filled into the container 60, and then a predetermined amount of the ink 51 is filled. After a predetermined time has passed in this state, as shown in FIG. 4(b), the pre-coating liquid 50 and the solvent 52 are mixed and move downward, and the resin 53 moves upward and precipitates. The resin 53 has a different color from the pre-coating liquid 50 and the solvent 52, and the boundary position between them can be visually identified. In this state, the amount of the solvent 52 mixed into the pre-coating liquid 50 can be evaluated by comparing the height H1 of the pre-coating liquid 50 before mixing shown in FIG. 4(a) with the height H2 of the mixed pre-coating liquid 50 and the solvent 52 shown in FIG. 4(b). In addition, the concentration of the solvent 52 in the ink 51 before mixing can be used to calculate what percentage of the solvent 52 in the ink 51 has mixed with the pre-coating liquid 50. By using such an evaluation method, the state of the resin 53 on the intermediate transfer body 10 can be easily evaluated. The appropriate ratio of the solvent 52 that is miscible with the pre-coating liquid 50 varies depending on the heating temperature of the heater 13 and the type of recording medium, for example, whether the solvent permeates into the recording medium, etc. For this reason, whether the solvent 52 is appropriately miscible with the pre-coating liquid 50 is evaluated by the above evaluation method.

[0025] Next, a modified example of the image forming apparatus will be described with reference to FIG. 5, in this embodiment, a heat roller 19 is used as a heating member instead of the heater 13 in the above embodiment. The heat roller 19 is heated by a predetermined method, such as by having a heater inside the heat roller 19. The heat roller 19 presses the transfer roller 17 with the intermediate transfer body 10 and the conveyor belt 18 sandwiched therebetween, forming a transfer nip N between the heat roller 19 and the transfer roller 17.

[0026] In this embodiment, the recording medium P is transported to the transfer nip N, and the resin precipitated on the intermediate transfer body 10 is heated by the heat roller 19, and the image on the intermediate transfer body 10 is transferred to the recording medium P. In this manner, in this embodiment, the heating of the resin and the transfer of the image can be performed simultaneously at the transfer position.

[0027] Although an embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0028] Examples of recording media include paper (plain paper), as well as cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, plastic film, prepreg, copper foil, and the like.

[0029] For example, aspects of the present invention are as follows. <1> An intermediate transfer body; a first coating member that applies a pre-coating liquid to the intermediate transfer body; a second coating member that coats the intermediate transfer body with an ink containing a solvent and a resin and a coloring material dissolved in the solvent; a heating member that heats the intermediate transfer body after the pre-coating liquid and the ink are applied, The image forming apparatus is characterized in that the heating member heats the intermediate transfer body on which the pre-coating liquid is mixed with the solvent and the resin is precipitated on the air-liquid interface side of the intermediate transfer body. <2> The heating member heats the intermediate transfer body downstream of a coating position of the second coating member on the intermediate transfer body and upstream of a transfer position where an image is transferred to a recording medium in a rotation direction of the intermediate transfer body. <1> The image forming apparatus is as described above. <3> The heating member is provided at a transfer position where the image on the intermediate transfer body is transferred to a recording medium, and the heating member presses the intermediate transfer body against the recording medium. <1> The image forming apparatus is as described above. <4> The solubility parameter of the solvent has a value between the solubility parameter of the pre-coating liquid and the solubility parameter of the resin. <1> from <3> The image forming apparatus according to any one of the preceding claims. <5> applying a pre-coating liquid to an intermediate transfer body; applying an ink containing a solvent and a resin and a coloring material dissolved in the solvent to the intermediate transfer body; heating the intermediate transfer member; and transferring an image from the intermediate transfer body to a recording medium, The image forming method is characterized in that the intermediate transfer body, which is mixed with the solvent and on which the resin is precipitated on the air-liquid interface side of the intermediate transfer body, is heated. [Explanation of symbols]

[0030] 1. Image forming device 10 Intermediate transfer body 11 First coating liquid ejection member (first coating member) 12 Inkjet head (second application member) 13 Heater (heating element) 19 Heat roller (heating member) 50 Tip coating liquid 51 Ink 52 Solvents 53 Resin N Transfer nip P Recording medium [Prior art documents] [Patent documents]

[0031] [Patent Document 1] Patent No. 6295841

Claims

1. An intermediate transfer body; a first coating member that applies a pre-coating liquid to the intermediate transfer body; a second coating member that coats the intermediate transfer body with an ink containing a solvent and a resin and a coloring material dissolved in the solvent; a heating member that heats the intermediate transfer body after the pre-coating liquid and the ink are applied, The image forming apparatus is characterized in that the heating member heats the intermediate transfer body on which the pre-coating liquid is mixed with the solvent and the resin is precipitated on the gas-liquid interface side of the intermediate transfer body.

2. 2. The image forming apparatus according to claim 1, wherein the heating member heats the intermediate transfer body downstream of the application position of the second application member relative to the intermediate transfer body in the rotation direction of the intermediate transfer body and upstream of the transfer position where the image is transferred to the recording medium.

3. 2. The image forming apparatus according to claim 1, wherein the heating member is provided at a transfer position where the image on the intermediate transfer body is transferred to a recording medium, and presses the intermediate transfer body against the recording medium.

4. 2. The image forming apparatus according to claim 1, wherein the solubility parameter of the solvent has a value between the solubility parameter of the pre-coating liquid and the solubility parameter of the resin.

5. applying a pre-coating liquid to an intermediate transfer body; applying an ink containing a solvent and a resin and a coloring material dissolved in the solvent to the intermediate transfer body; heating the intermediate transfer member; and transferring an image from the intermediate transfer body to a recording medium, the intermediate transfer body on which the resin has been mixed with the solvent and precipitated onto the air-liquid interface side of the intermediate transfer body is heated;

Images