JP7708580B2 - Image transfer sheet and image transfer method - Google Patents

Description

The present invention relates to an image transfer sheet and an image transfer method.

A method of printing an image on an image transfer sheet using a printer and transferring the image on the image transfer sheet to a transfer target has been known for some time. The configuration of the image transfer sheet for this purpose is also known. For example, Patent Document 1 discloses an image transfer sheet in which an image layer is formed on release paper with a peelable adhesive layer by a UV printer, and a transfer film is superimposed on the image layer. The transfer film has peelability with respect to the image layer and easy adhesion with respect to the adhesive layer. Therefore, according to Patent Document 1, when the adhesive layer of the image transfer sheet from which the release paper has been peeled off is pressed against the transfer target and then the transfer film is peeled off, the image is transferred to the transfer target, and the adhesive layer outside the image is peeled off together with the transfer film. Patent Document 1 claims that this makes it possible to easily manufacture an image transfer sheet that can transfer-print only the image.

JP 2017-209931 A

The image transfer sheet and image transfer method disclosed in Patent Document 1 require special printing media: release paper with a peelable adhesive layer, and a transfer film that is peelable from the image layer and easily adheres to the adhesive layer. On the other hand, the typical conventional method of printing an image on printing media with a sticker attached to the release paper and then cutting around the image requires time to cut the printing media, so it is difficult to say that this is an easy method of producing an image transfer sheet.

The present invention was made in consideration of these points, and its purpose is to provide an image transfer sheet that does not require the use of special materials and is easy to manufacture. It is also to provide a method for producing such an image transfer sheet and transferring an image to a target object.

The image transfer sheet disclosed herein comprises a release paper, a protective sheet having an adhesive layer, an image layer which is a layer of fully cured photocurable process color ink and is provided between the release paper and the protective sheet, an overcoat layer which is a layer of fully cured photocurable transparent ink and is provided between the protective sheet and the image layer and is attached to the adhesive layer of the protective sheet, and an adhesive layer which is a layer of semi-cured photocurable ink, has adhesiveness to a transfer target, and is provided between the release paper and the image layer.

The image transfer sheet functions as an image transfer sheet because the image of the image layer can be transferred to the object by adhering the adhesive layer to the object. Moreover, the image transfer sheet can use a general-purpose release paper, so there is no need to use special materials. Furthermore, the image transfer sheet can be produced without cutting, making it easy to produce.

The image transfer method disclosed herein includes the steps of ejecting photocurable ink by an inkjet printer and irradiating the ink with light to semi-cure it, thereby forming an adhesive layer on a release paper that is adhesive to the transfer target, ejecting photocurable process color ink by an inkjet printer and irradiating the process color ink with light to completely cure it, thereby forming an image layer above the adhesive layer, ejecting photocurable transparent ink by an inkjet printer and irradiating the transparent ink with light to completely cure it, thereby forming an overcoat layer above the image layer, attaching the adhesive layer of a protective sheet having an adhesive layer to the overcoat layer, peeling the release paper from the adhesive layer, contacting the adhesive layer after the release paper is peeled off with the transfer target, pressing the protective sheet toward the adhesive layer while the adhesive layer is in contact with the transfer target, and peeling the protective sheet from the overcoat layer.

According to the above image transfer method, the above image transfer sheet can be produced and used to transfer an image to a target object.

FIG. 2 is a schematic cross-sectional view of the image transfer sheet according to the first embodiment. 4 is a flowchart showing a procedure for producing an image transfer sheet according to the first embodiment. FIG. 2 is a schematic diagram of a step of forming an adhesive layer. FIG. 2 is a schematic diagram of a step of forming a concealing layer. 1 is a schematic diagram of the steps of forming an image layer. 2A to 2C are schematic diagrams illustrating steps of forming an overcoat layer. 4 is a flowchart showing a procedure for image transfer using an image transfer sheet. FIG. 2 is a schematic diagram of a step of peeling off the release paper. FIG. 2 is a schematic diagram of a bonding step. FIG. 13 is a schematic diagram of a step of peeling off an application sheet. FIG. 11 is a schematic cross-sectional view of an image transfer sheet according to a second embodiment. 10 is a flowchart showing a procedure for producing an image transfer sheet according to a second embodiment. 3 is a schematic cross-sectional view of the image transfer sheet after image transfer to a transfer target. FIG.

Below, image transfer sheets and image transfer methods according to several embodiments will be described with reference to the drawings. Naturally, the embodiments described here are not intended to limit the present invention in any particular way. In addition, the same reference numerals are used for components and parts that perform the same function, and duplicate descriptions will be omitted or simplified.

[First embodiment]
[Configuration of image transfer sheet]
Fig. 1 is a schematic cross-sectional view of an image transfer sheet 10 according to the first embodiment. The image transfer sheet 10 is a sheet that transfers an image to a transfer target 5 (see Fig. 9) by being attached to the transfer target 5. As shown in Fig. 1, the image transfer sheet 10 includes a release paper 20, an adhesive layer 30 formed on the release paper 20, a concealing layer 40 formed on the adhesive layer 30, an image layer 50 formed on the concealing layer 40, an overcoat layer 60 formed on the image layer 50, and an application sheet 70 attached on the overcoat layer 60.

The release paper 20 is a substrate on which the adhesive layer 30 is formed. The release paper 20 is configured so that the adhesive layer 30 can be formed and the adhesive layer 30 can be easily peeled off. The release paper 20 is, for example, a sheet of paper with a release treatment applied to the surface. The release treatment can be, for example, the formation of a silicone resin layer. However, there are no particular limitations on the material of the release paper 20 or the method of surface treatment. A general sticker mount or the like can be suitably used as the release paper 20. Although it is called "release paper", the material of the release paper 20 is not limited to paper and may be, for example, a resin sheet.

The adhesive layer 30 is a layer having adhesive properties, and is adhered to the release paper 20 when the image transfer sheet 10 is not adhered to the transfer target 5. When the image transfer sheet 10 is adhered to the transfer target 5, the adhesive layer 30 is adhered to the transfer target 5. The adhesive layer 30 has adhesive properties to the transfer target 5. Here, "having adhesive strength" means that the peel adhesion at a peel angle of 180 degrees and a speed of 300 mm/min as specified in JIS Z 0237 is 0.5 N/10 mm or more. However, the adhesive strength of the adhesive layer 30 is not limited to a level that can generally be said to have "adhesive strength". In this embodiment, the adhesive layer 30 is formed of a photocurable white ink. More specifically, the adhesive layer 30 is a layer in which the photocurable white ink is semi-cured on the release paper 20. Here, the photocurable ink is a UV ink containing an ultraviolet curable resin that is cured by irradiating ultraviolet light. However, there are no particular limitations on the components, characteristics, etc. of the photocurable ink. The adhesive layer 30 is formed on the release paper 20 by printing using an inkjet printer 100 (hereinafter, printer 100, see FIG. 3). The printing process will be described later.

The adhesive layer 30 is configured to have the same shape as the image layer 50. This allows for a borderless transfer image to be obtained, similar to a sticker with the periphery of the image cut out. There are no particular limitations on the thickness of the adhesive layer 30.

The concealing layer 40 is a layer in which photocurable white ink is completely cured on the adhesive layer 30, and is configured to be opaque. The concealing layer 40 has a thickness that makes it impossible to see through to the bottom. The concealing layer 40 is a layer provided so that the image layer 50 develops a clear color regardless of the color of the transfer object 5. The adhesive layer 30 is thin, and may not provide sufficient concealment by itself, so the concealing layer 40 is provided. Here, the thickness of the concealing layer 40 is thicker than the adhesive layer 30. However, as long as the concealing layer 40 can be configured to be opaque, the thickness of the concealing layer 40 is not particularly limited. The concealing layer 40 is also formed by printing with the printer 100. The concealing layer 40 is also configured to have the same shape as the image layer 50.

The image layer 50 is a layer that constitutes the image to be transferred to the transfer target 5. The image layer 50 is formed on the concealing layer 40. The image layer 50 is a layer in which the process color ink is completely cured on the concealing layer 40. The process color ink here is a photocurable ink. The process color ink includes, for example, CMYK (cyan, magenta, yellow, black) ink. However, the colors of the process color ink are not particularly limited. The image layer 50 is also formed by printing with the printer 100.

As shown in FIG. 1, the image layer 50 may be composed of a plurality of parts spaced apart from one another. The plurality of parts spaced apart from one another of the image layer 50 may each constitute an image to be transferred to a different object 5 or to a different location on the object 5. That is, the image layer 50 may include a plurality of images to be transferred to different locations. The image layer 50 may also constitute a three-dimensional image having thickness.

The overcoat layer 60 is a layer for protecting the image layer 50, and is formed on the image layer 50. The overcoat layer 60 is a layer in which a photocurable transparent ink is completely cured on the image layer 50. The overcoat layer 60 may be formed to have a smooth glossy surface, or may be formed to have an uneven surface and a matte finish with no gloss. The overcoat layer 60 may also be formed with a three-dimensional pattern (texture pattern) to impart a design effect. The overcoat layer 60 is also formed by printing with the printer 100. The overcoat layer 60 is also configured to have the same shape as the image layer 50.

The application sheet 70 is a sheet attached onto the overcoat layer 60. The application sheet 70 is an example of a protective sheet that protects the printed layer consisting of the adhesive layer 30, the concealing layer 40, the image layer 50, and the overcoat layer 60. Here, the application sheet 70 is a transparent resin film with an adhesive layer 71 formed on one surface. However, the material and configuration of the application sheet 70 are not particularly limited as long as it can be attached onto the overcoat layer 60. Here, the application sheet 70 is configured to have the same shape as the release paper 20. The application sheet 70 is attached to the release paper 20 on which the printed layer is formed by the adhesive layer 71. A part of the adhesive layer 71 of the application sheet 70 is attached to the overcoat layer 60, and the other part is attached to the part of the release paper 20 on which the printed layer is not formed. The application sheet 70 and the release paper 20 are members that are removed after the image transfer sheet 10 is transferred to the transfer target 5. The application sheet 70 and the release paper 20 are provided to improve the convenience of the image transfer sheet 10 in storage, carrying, transfer work, etc.

[Method of producing image transfer sheet]
A method for producing the image transfer sheet 10 will be described below. FIG. 2 is a flow chart showing the procedure for producing the image transfer sheet 10 according to the present embodiment. As shown in FIG. 2, in the production of the image transfer sheet 10, first, in steps S01 and S02, an adhesive layer 30 having adhesive properties to the transfer target 5 is formed on the release paper 20. In steps S01 and S02, the printer 100 ejects photocurable white ink and irradiates the white ink with light to semi-cure it, thereby forming the adhesive layer 30 on the release paper 20. More specifically, in step S01, the printer 100 ejects photocurable white ink on the release paper 20. In step S02, the white ink ejected on the release paper 20 is irradiated with light to semi-cure the white ink, thereby forming the adhesive layer 30 having adhesive properties.

FIG. 3 is a schematic diagram showing the steps of forming the adhesive layer 30 (steps S01 and S02). As shown in FIG. 3, the printer 100 includes a flatbed 110, a carriage 120, a recording head 130 mounted on the carriage 120, and two light irradiation devices 141 and 142 also mounted on the carriage 120. The flatbed 110 is a support table that supports the printing object. Here, the release paper 20 is placed on the flatbed 110 as the printing object. The flatbed 110 is moved in the X direction (perpendicular to the paper surface of FIG. 3) by a bed moving device (not shown). As the flatbed 110 moves in the X direction, the release paper 20 moves in the X direction. The carriage 120 is moved in the Y direction (left and right direction in FIG. 3) by a carriage moving device (not shown). As the carriage 120 moves in the Y direction, the recording head 130 and the light irradiation devices 141 and 142 mounted on the carriage 120 also move in the Y direction. In addition, U and D in FIG. 3 represent the upper and lower sides, respectively. Y1 and Y2 in FIG. 3 each represent one side of the Y direction. The X direction, Y direction, and up-down direction are mutually orthogonal. However, these directions are merely defined for the convenience of explanation, and do not limit the installation mode of the printer 100, nor limit the present invention in any way.

As shown in FIG. 3, the recording head 130 includes a plurality of ink heads 130W, 130G, 130C, 130M, 130Y, and 130K. The ink head 130W is configured to eject photo-curable white ink. The ink head 130G is configured to eject photo-curable transparent ink. The ink heads 130M to 130K are configured to eject photo-curable process color inks. More specifically, the ink head 130C ejects photo-curable cyan ink. The ink head 130M ejects photo-curable magenta ink. The ink head 130Y ejects photo-curable yellow ink. The ink head 130K ejects photo-curable black ink. However, the process color inks are not limited to CMYK inks. As shown in FIG. 3, the plurality of ink heads 130W to 130K are arranged in a line in the Y direction. Although not shown in the figure, each of the ink heads 130W to 130K extends in the X direction.

The light irradiation devices 141 and 142 are provided on the side of the carriage 120 in the Y direction. One light irradiation device 141 is disposed in the Y1 direction from the recording head 130. The other light irradiation device 142 is disposed in the Y2 direction from the recording head 130. However, the light irradiation devices may be provided only in the Y1 direction or the Y2 direction from the recording head 130. The light irradiation devices 141 and 142 irradiate light that hardens the ink ejected from the recording head 130. The light irradiation devices 141 and 142 are provided with a plurality of ultraviolet irradiation LEDs (not shown) and are configured to be able to adjust the intensity of the light irradiated by turning off some of the ultraviolet irradiation LEDs. However, the method by which the light irradiation devices 141 and 142 adjust the light intensity is not limited to the above. The light irradiation devices 141 and 142 may adjust the light intensity by, for example, adjusting the current flowing through the ultraviolet irradiation LEDs.

In the steps of forming the adhesive layer 30 (steps S01 and S02), the printer 100 ejects white ink from the ink head 130W toward the release paper 20 on the flatbed 110 while moving the carriage 120 in the Y1 direction. At this time, the light irradiation device 142 on the rear side of the movement direction of the carriage 120 irradiates light with an intensity that does not completely cure the white ink. The white ink that has landed on the release paper 20 is irradiated with light from the light irradiation device 142. This semi-cures the white ink. Note that the white ink is semi-cured with a grainy texture remaining because it receives light immediately after it has landed on the release paper 20. In FIG. 2, step S02 is illustrated after step S01, but this is for convenience of illustration, and steps S01 and S02 may be performed simultaneously, as described above.

The printer 100 repeats the above while changing the relative position between the release paper 20 and the carriage 120 by moving the flatbed 110 in the X direction. This forms an adhesive layer 30 at a predetermined location on the release paper 20. However, if the adhesive layer 30 is small and there is no need to move the flatbed 110, the movement of the flatbed 110 may be omitted. The adhesive layer 30 may be formed of a single layer of white ink, or may be formed of multiple layers of white ink stacked vertically. In addition, the white ink of the adhesive layer 30 may not be semi-cured immediately after landing on the release paper 20, but may be semi-cured after time has passed since landing and flattened (hereinafter also referred to as leveling).

2, in steps S03 and S04 following the step of forming the adhesive layer 30 (steps S01 and S02), the printer 100 forms an opaque concealing layer 40 on the adhesive layer 30. In steps S03 and S04, the printer 100 ejects white ink and irradiates the white ink with light to completely harden it, forming an opaque concealing layer 40 on the adhesive layer 30. In detail, in step S03, the printer 100 ejects white ink on the adhesive layer 30. In step S04, the white ink ejected on the adhesive layer 30 is irradiated with light to completely harden the white ink, forming an opaque concealing layer 40. FIG. 4 is a schematic diagram of the step of forming the concealing layer 40 (steps S03 and S04). In steps S03 and S04, as in steps S01 and S02, the carriage 120 is moved in the Y1 direction while ejecting white ink from the ink head 130W toward the adhesive layer 30. At this time, the light irradiation device 141 on the front side in the movement direction of the carriage 120 emits light with an intensity that completely cures the white ink. When the carriage 120 returns in the Y2 direction, the white ink that has landed on the adhesive layer 30 is irradiated with light from the light irradiation device 141. This completely cures the white ink. Since the white ink receives light after a period of time has passed since it landed, it is leveled. This reduces the gaps between the ink dots of the white ink, improving the concealment ability of each white ink layer. However, because the thickness of each white ink layer becomes thinner due to leveling, the concealment layer 40 is formed by stacking multiple white ink layers.

However, the method of forming the concealing layer 40 is not limited as long as the desired concealing properties are obtained. If possible, the concealing layer 40 may be formed from a single layer of white ink. In addition, the white ink of the concealing layer 40 may be cured immediately after landing on the adhesive layer 30.

In the following steps S05 and S06, the image layer 50 is formed on the adhesive layer 30 and the concealing layer 40. In steps S05 and S06, the printer 100 ejects photocurable process color inks and irradiates the process color inks with light to completely cure them, thereby forming the image layer 50 on the concealing layer 40. More specifically, in step S05, the printer 100 ejects process color inks onto the concealing layer 40. In step S06, the process color inks ejected onto the concealing layer 40 are completely cured to form the image layer 50. FIG. 5 is a schematic diagram of the steps (steps S05 and S06) of forming the image layer 50. Steps S05 and S06 are similar to steps S01 and S02, except that the ejected inks are process color inks, and the color image specified by the manufacturer of the image transfer sheet 10 is formed by the process color inks.

In the following steps S07 and S08, the overcoat layer 60 is formed on the image layer 50. In steps S07 and S08, the printer 100 ejects photocurable transparent ink and irradiates the transparent ink with light to completely cure it, thereby forming the overcoat layer 60 on the image layer 50. In detail, in step S07, the printer 100 ejects transparent ink on the image layer 50. In step S08, the transparent ink ejected on the image layer 50 is completely cured to form the overcoat layer 60. FIG. 6 is a schematic diagram of the steps (steps S07 and S08) of forming the overcoat layer 60. Steps S07 and S08 are similar to steps S03 and S04, except that the ejected ink is transparent ink, and the thickness of the overcoat layer 60 does not need to be as thick as the concealing layer 40. The transparent ink is leveled because it is exposed to light after a period of time has elapsed after it has landed on the image layer 50. This makes the surface of the overcoat layer 60 smooth, and the overcoat layer 60 has a glossy finish. As a result, the glossiness of the image transfer sheet 10 is improved. However, as described above, the overcoat layer 60 may be formed in a matte finish that eliminates the gloss, or may have a texture pattern that aims for a design effect. In addition, the thickness of the overcoat layer 60 is not particularly limited, and may be the same as or thicker than the concealing layer 40.

In step S09, the application sheet 70 is applied as a protective sheet onto the overcoat layer 60. The adhesive layer 71 of the application sheet 70 is attached to the overcoat layer 60. This completes the image transfer sheet 10. The transferred image of the image transfer sheet 10 thus formed is a color image specified by the manufacturer (however, if the specified image is a black and white image, the image is a black and white image). The image transfer sheet 10 is also configured to have no border around the transferred image. However, it is also possible to create a border around the transferred image, for example, by using the concealing layer 40.

[Image transfer method]
Next, the procedure for transferring an image using the image transfer sheet 10 will be described. Although not shown, when a plurality of transfer images to be transferred to a plurality of locations are formed on one image transfer sheet 10, the image transfer sheet 10 may be cut into a plurality of portions each including one transfer image prior to transfer. FIG. 7 is a flowchart showing the procedure for transferring an image using the image transfer sheet 10. As shown in FIG. 7, when transferring an image using the image transfer sheet 10, first, in step S11, the upper surface of the application sheet 70 is rubbed with a plate-shaped squeegee 200 (see FIG. 9). This allows the adhesive layer 30, the concealing layer 40, the image layer 50, and the overcoat layer 60 to be more closely attached. However, this operation may be performed when the image transfer sheet 10 is produced (after step S09). In addition, the object for rubbing the upper surface of the application sheet 70 is not limited to the plate-shaped squeegee 200, and may be, for example, the user's hand or a baren. Step S11 may be omitted if not particularly necessary.

As shown in FIG. 7, in the next step S12, the release paper 20 is peeled off from the adhesive layer 30. FIG. 8 is a schematic diagram of step S12. As shown in FIG. 8, in step S12, the release paper 20 is peeled off, but the application sheet 70 remains on the image transfer sheet 10 without being peeled off.

In step S13, the adhesive layer 30 after the release paper 20 is peeled off is brought into contact with the transfer target 5. In the following step S14, the application sheet 70 is pressed toward the adhesive layer 30 while the adhesive layer 30 is in contact with the transfer target 5. FIG. 9 is a schematic diagram of step S14. As shown in FIG. 9, in step S14, for example, the application sheet 70 is pressed toward the adhesive layer 30 by rubbing the upper surface of the application sheet 70 with a squeegee 200. As a result, the adhesive layer 30 adheres to the transfer target 5 and is adhered to the transfer target 5. In step S14, it is sufficient to bring the adhesive layer 30 into contact with the transfer target 5. Therefore, in step S14, the application sheet 70 may be simply pressed toward the transfer target 5 without rubbing.

As shown in FIG. 7, in step S15 after step S14, the application sheet 70 is peeled off from the overcoat layer 60. FIG. 10 is a schematic diagram of step S15. This completes the transfer of the image printed on the image transfer sheet 10 to the transfer target 5.

[Effects of the First Embodiment]
As described above, the image transfer sheet 10 according to the present embodiment includes a release paper 20, an application sheet 70 having an adhesive layer 71, and an image layer 50 in which photocurable process color ink is completely cured and provided between the release paper 20 and the application sheet 70. The image transfer sheet 10 further includes an overcoat layer 60 provided between the application sheet 70 and the image layer 50, and an adhesive layer 30 provided between the release paper 20 and the image layer 50. The overcoat layer 60 is a layer in which photocurable transparent ink is completely cured, and is attached to the adhesive layer 71 of the application sheet 70. The adhesive layer 30 is a layer in which photocurable white ink is semi-cured, and has adhesiveness to the transfer target 5. In the production of the image transfer sheet 10, a step of cutting the periphery of the image is not required. Therefore, the image transfer sheet 10 according to the present embodiment can be produced easily and quickly. In addition, the image transfer sheet 10 can be produced using a general-purpose release paper 20 and ink, rather than a special material as described in Patent Document 1.

Furthermore, the image transfer sheet 10 according to this embodiment is a layer of completely cured white ink, and is provided with an opaque concealing layer 40 provided between the adhesive layer 30 and the image layer 50. Therefore, the color of the image layer 50 formed on the concealing layer 40 can be made clear regardless of the color of the transfer target 5. In this embodiment, the adhesive layer 30 is also formed with white ink, but since a problem may occur in the transfer process if the adhesive layer 30 is made thick, the adhesive layer 30 is made thin and the concealing layer 40 is provided. In detail, if the semi-cured adhesive layer 30 is made thick, the adhesive layer 30 is likely to protrude outside the image transfer sheet 10 when the image transfer sheet 10 is rubbed in the transfer process. In addition, if the semi-cured adhesive layer 30 is made thick, the image layer 50 and the overcoat layer 60 are likely to move and shift on the transfer target 5 when the image transfer sheet 10 is rubbed in the transfer process or when a force is applied to the image transfer sheet 10 after the transfer process is completed. Therefore, in this embodiment, the adhesive layer 30 is made thin, and the concealing layer 40 is made thicker than the adhesive layer 30.

In this embodiment, the ink forming the concealing layer 40 is white ink, but it may be another opaque special color ink. For example, if it is desired to give the image transfer sheet 10 a metallic finish, the ink forming the concealing layer 40 may be a metallic ink. In this embodiment, the adhesive layer 30 is also formed of white ink to further improve the concealing properties, but the ink forming the adhesive layer 30 may be a special color ink other than white ink, for example, a transparent ink. Furthermore, the process color ink forming the image layer 50 is not limited to a photocurable ink. The process color ink forming the image layer 50 may be, for example, a heat-curable ink.

The image transfer sheet 10 according to this embodiment further includes an overcoat layer 60 in which the transparent ink is completely cured on the image layer 50. According to this configuration, the image layer 50 is protected by the overcoat layer 60, and the durability of the image transfer sheet 10 is improved. Furthermore, the image transfer sheet 10 according to this embodiment further includes an application sheet 70 attached on the overcoat layer 60. According to this configuration, the image transfer sheet 10 before transfer can be protected by the application sheet 70, and the image transfer sheet 10 can be easily stored and carried. In this embodiment, as in step S14 of FIG. 7, the adhesive layer 30 is brought into contact with the transfer target 5 and the application sheet 70 is rubbed, thereby adhering the adhesive layer 30 to the transfer target 5. Therefore, the application sheet 70 may be scratched by the operation of rubbing the application sheet 70. However, the application sheet 70 is peeled off in step S15 after step S14. Therefore, the image transfer sheet 10 can be adhered to the transfer target 5 without scratching or soiling the image transfer sheet 10.

[Second embodiment]
In the second embodiment, the image transfer sheet has an adhesive layer of another type and does not have a concealing layer. The other configurations of the image transfer sheet according to the second embodiment are common to those of the first embodiment. In the following description of the second embodiment, the same reference numerals as those of the first embodiment are used for members having the same functions as those of the first embodiment, and duplicated descriptions are omitted or simplified.

[Configuration of image transfer sheet]
Fig. 11 is a schematic cross-sectional view of an image transfer sheet 11 according to the second embodiment. As shown in Fig. 11, the image transfer sheet 11 according to this embodiment includes a release paper 20, an adhesive layer 31 formed on the release paper 20, an image layer 50 formed on the adhesive layer 31, an overcoat layer 60 formed on the image layer 50, and an application sheet 70 attached on the overcoat layer 60.

The release paper 20 may be the same as in the first embodiment, or may be different. The release paper 20 is preferably one that is easily available, such as a general sticker mount, but is not limited thereto. In this embodiment, the adhesive layer 31 is formed of a light-curable transparent ink. The adhesive layer 31 is a layer in which the light-curable transparent ink is semi-cured on the release paper 20, and has adhesive properties for the transfer object 5. The adhesive layer 31 is a transparent layer. The adhesive layer 31 is formed on the release paper 20 by, for example, an inkjet printer 100 as shown in FIG. 3.

The adhesive layer 31 is also configured to have the same shape as the image layer 50. This allows a borderless transfer image to be obtained, as in the first embodiment. The thickness of the adhesive layer 31 may be approximately the same as the preferred thickness of the adhesive layer 30 in the first embodiment. However, the thickness of the adhesive layer 31 is not particularly limited.

The image layer 50 is a layer in which the process color ink is completely cured on the adhesive layer 31. The overcoat layer 60 is a layer in which the transparent ink is completely cured on the image layer 50. The image layer 50 and the overcoat layer 60 are the same as those in the first embodiment. However, the image layer 50 may be a layer in which the process color ink is completely cured on the adhesive layer 31, and the ink used and its thickness are not particularly limited. The overcoat layer 60 may be a layer in which the transparent ink is completely cured on the image layer 50, and the ink used and its thickness are also not particularly limited. The application sheet 70 is also not particularly limited as long as it has an adhesive layer 71 and functions as a protective sheet.

[Method of producing image transfer sheet]
A method for producing the image transfer sheet 11 according to the second embodiment will be described below. FIG. 12 is a flowchart showing the procedure for producing the image transfer sheet 11 according to the second embodiment. As shown in FIG. 12, in the production of the image transfer sheet 11 according to this embodiment, first, in step S21, a photocurable transparent ink is discharged onto the release paper 20 by the printer 100. In the following step S22, the transparent ink discharged onto the release paper 20 is irradiated with light to semi-cure the transparent ink, thereby forming an adhesive layer 31 having adhesive properties. The transparent ink of the adhesive layer 31 may be semi-cured immediately after landing on the release paper 20, or may be semi-cured after leveling after landing. The adhesive layer 31 may be formed from one layer of transparent ink, or may be formed by laminating a plurality of layers of transparent ink.

In the next step S23, the printer 100 ejects process color ink onto the adhesive layer 31. In step S24, the process color ink ejected onto the adhesive layer 31 is completely cured to form the image layer 50.

In step S25, the printer 100 ejects transparent ink onto the image layer 50. In step S26, the transparent ink ejected onto the image layer 50 is completely cured to form the overcoat layer 60. The overcoat layer 60 may be formed in a glossy finish, or may be formed in a matte finish if necessary. The overcoat layer 60 may also have a texture pattern for a design effect. In step S27, an application sheet 70 is attached as a protective sheet onto the overcoat layer 60. The image transfer sheet 11 according to the second embodiment is thus completed.

The method of image transfer using the image transfer sheet 11 according to the second embodiment is the same as that of the first embodiment, and therefore will not be described. FIG. 13 is a schematic cross-sectional view of the image transfer sheet 11 after image transfer to the transfer target 5 is completed. As shown in FIG. 13, after image transfer is completed, the adhesive layer 31 of the image transfer sheet 11 is adhered to the transfer target 5. An image layer 50 is formed on the adhesive layer 31, and an overcoat layer 60 is formed on the image layer 50. Finally, the release paper 20 and application sheet 70 are removed.

[Effects of the Second Embodiment]
As described above, the image transfer sheet 11 according to the present embodiment includes the release paper 20, the adhesive layer 31, which is a layer of photocurable transparent ink semi-cured on the release paper 20 and has adhesive properties, the image layer 50 in which the process color ink is completely cured on the adhesive layer 31, the overcoat layer 60 in which the transparent ink is completely cured on the image layer 50, and the application sheet 70 attached on the overcoat layer 60. The image transfer sheet 11 can be easily and quickly manufactured without using special materials, as with the image transfer sheet 10 according to the first embodiment. The image transfer sheet 11 according to the present embodiment has a transparent adhesive layer 31, and the image layer 50 is formed on the transparent adhesive layer 31. The image transfer sheet 11 according to the second embodiment has fewer printing layers than the image transfer sheet 10 according to the first embodiment, and can be manufactured even more easily and quickly than the image transfer sheet 10 according to the first embodiment. The image transfer sheet 11 according to the present embodiment can be suitably used in cases where the influence of the color of the transfer target 5 is not particularly problematic, or when it is desired to show the color of the transfer target 5 through for a more natural finish. For example, when the transfer object 5 is white, the color of the image transfer sheet 11 according to the second embodiment is generally the same as that of the image transfer sheet 10 according to the first embodiment.

The ink forming the adhesive layer 31 does not have to be a transparent photocurable ink, and may be, for example, an opaque photocurable ink. The ink forming the adhesive layer 31 may be, for example, a photocurable white ink.

[Other embodiments]
Although some preferred embodiments of the present invention have been described above, the above-described embodiments are merely examples, and the present invention can be embodied in various other forms.

For example, in the above embodiment, the image transfer sheet has an overcoat layer on the image layer and further has a protective sheet attached to the overcoat layer, but it does not have to have an overcoat layer and a protective sheet. If the image transfer sheet has a protective sheet, the protective sheet may be attached directly to the image layer or via another layer. The layer interposed between the image layer and the protective sheet is not limited to an overcoat layer made of transparent ink, and may be, for example, an overcoat layer made of a metallic ink layer or a white ink layer that is partially formed on the image layer and provides a design effect.

In the above embodiment, the image transfer sheets 10 and 11 were produced by a flatbed type printer 100 in which the flatbed 110 on which the print object is placed moves, but they may be produced by other types of printers, for example, roll-to-roll type printers that print while feeding a roll of recording medium. In that case, the recording medium loaded into the roll-to-roll type printer may be release paper wound in a roll.

Unless otherwise specifically stated, the embodiments do not limit the present invention.

5 Transfer target 10 Image transfer sheet (first embodiment)
11 Image transfer sheet (second embodiment)
20 Release paper 30 Adhesive layer (first embodiment)
31 Adhesive layer (second embodiment)
40: concealing layer 50: image layer 60: overcoat layer 70: application sheet (protective sheet)
100 Inkjet printer

Claims (3)

A release paper;
A protective sheet having an adhesive layer;
an image layer, which is a layer of a photocurable process color ink that has been completely cured, and which is provided between the release paper and the protective sheet;
an overcoat layer, which is a layer in which a photocurable transparent ink is completely cured, and which is provided between the protective sheet and the image layer and is attached to the adhesive layer of the protective sheet;
an adhesive layer that is a layer of a semi-cured photocurable opaque ink, the adhesive layer having adhesiveness to a transfer target and that is provided between the release paper and the image layer ;
and an opaque concealing layer, the opaque ink being a fully cured layer, disposed between the adhesive layer and the image layer .
Image transfer sheet. The thickness of the concealing layer is greater than the thickness of the adhesive layer.
The image transfer sheet according to claim 1 . A step of ejecting a photocurable opaque ink using an inkjet printer and semi-curing the opaque ink by irradiating the ink with light to form an adhesive layer on a release paper, the adhesive layer having adhesiveness to a transfer target;
a step of ejecting a photocurable process color ink by an inkjet printer and irradiating the process color ink with light to completely cure the ink, thereby forming an image layer on the adhesive layer;
After the step of forming the adhesive layer and before the step of forming the image layer, the step of ejecting the opaque ink by an inkjet printer and irradiating the opaque ink with light to completely harden the ink, thereby forming an opaque hiding layer on the adhesive layer;
a step of ejecting a photocurable transparent ink by an inkjet printer and completely curing the transparent ink by irradiating the ink with light to form an overcoat layer on the image layer;
A step of attaching an adhesive layer of a protective sheet having an adhesive layer to the overcoat layer;
peeling the release paper from the adhesive layer;
contacting the adhesive layer after the release paper has been peeled off with an object to be transferred;
pressing the protective sheet toward the adhesive layer while the adhesive layer is in contact with a transfer target;
peeling the protective sheet from the overcoat layer;
13. A method for transferring an image comprising: