Image forming method

Abstract

To provide an image forming method in which an image with good color development can be formed on a substrate using thermal transfer, without deteriorating texture of the substrate.SOLUTION: The image forming method includes: a resin layer forming step of allowing a resin liquid containing a resin component capable of being polymerized by ultraviolet irradiation to adhere to the substrate by ejecting the resin liquid from an inkjet head, and fixing the resin component as a resin layer to the substrate by ultraviolet irradiation; and a transfer step of allowing a transfer sheet having a sublimable dye ink layer to adhere to the resin layer and transferring a sublimable dye ink in the sublimable dye ink layer to the resin layer by heating.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an imaging method for forming an image on a substrate using thermal transfer. [Background technology]

[0002] Patent Document 1 discloses a method for transferring dyes to a polyvinyl chloride molding by forming a cured film of ultraviolet-curable resin on the polyvinyl chloride molding, and then layering sublimation dye transfer paper on this film and applying pressure and heat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 63-38475 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, a polyvinyl chloride molded product is coated with an ultraviolet-curable resin by knife coating or gravure coating. Therefore, the polyvinyl chloride molded product is limited to a sheet shape, and full-color printing on a three-dimensional object such as a cup is difficult. On the other hand, it is possible to print on a three-dimensional object by an inkjet method using an ultraviolet-curable ink. However, as the print density and color increase, the thickness of the ink film increases, which leads to poor adhesion between the three-dimensional object and the ink film and loss of the texture of the surface of the three-dimensional object.

[0005] An object of the present invention is to provide an image forming method that uses thermal transfer to form an image with good color development on a substrate without damaging the texture of the substrate. [Means for solving the problem]

[0006] (1) The present invention relates to an image forming method for forming an image on a substrate, the image forming method comprising a resin layer forming step of adhering a resin liquid containing a resin component that polymerizes upon ultraviolet irradiation to the substrate by ejecting the resin liquid from an inkjet head and fixing the resin component to the substrate as a resin layer by irradiating ultraviolet rays, and a transfer step of adhering a transfer sheet having a sublimation dye ink layer to the resin layer and transferring the sublimation dye ink of the sublimation dye ink layer to the resin layer by heating.

[0007] According to the above image forming method, an image with good color development and texture is formed on a substrate.

[0008] (2) The substrate may contain an inorganic material or a resin material having a glass transition point of 90° C. or higher.

[0009] This results in a blur-free image.

[0010] (3) The resin layer may have a glass transition point within a range of 0°C to 70°C.

[0011] This provides excellent peelability of the transfer sheet.

[0012] (4) The resin layer may have a thickness within a range of 5 μm to 50 μm.

[0013] This provides good color development in the image and good adhesion between the substrate and the resin layer.

[0014] (5) The resin liquid includes a first resin liquid including a first resin component and a second resin liquid including a second resin component, and the resin layer forming process includes a first process of adhering the first resin liquid to the substrate by ejecting it from an inkjet head and fixing the first resin component to the substrate as a base layer by irradiating with ultraviolet light, and a second process of adhering the second resin liquid to the substrate by ejecting it from an inkjet head and laminating the second resin component as a surface layer on the base layer by irradiating with ultraviolet light, and a glass transition point of the base layer may be lower than a glass transition point of the surface layer.

[0015] This provides good adhesion between the base layer and the substrate, and good peelability of the transfer sheet from the surface layer.

[0016] (6) The base layer may have a glass transition point of less than 25°C, and the surface layer may have a glass transition point within the range of 25°C to 55°C.

[0017] (7) The surface layer may have a thickness of 15 μm or more.

[0018] This results in good color development in the image.

[0019] (8) The resin liquid may further include a third resin liquid containing the resin component, the third resin liquid including a colorant, and the first resin liquid and the second resin liquid not including a colorant, and the resin layer forming process may include a third process, which is performed after the first process and before the second process, of depositing the third resin liquid by ejecting it from an inkjet head and irradiating it with ultraviolet light to form an intermediate layer between the base layer and the surface layer.

[0020] This provides good adhesion between the base layer and the substrate, and good peelability of the transfer sheet from the surface layer, and good color development of the image.

[0021] (9) In the transfer step, a heating temperature when the sublimation dye ink of the sublimation dye ink layer is transferred to the resin layer may be within a range of 120°C to 240°C. Effect of the Invention

[0022] According to the present invention, a highly colored image is formed on a substrate by thermal transfer, without impairing the texture of the substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, a preferred embodiment of the present invention will be described. Note that this embodiment is merely one embodiment of the present invention, and it goes without saying that the embodiment can be changed without departing from the gist of the present invention.

[0024] The image forming method for forming an image on a substrate includes a resin layer forming step and a transfer step. The substrate is not particularly limited as long as a resin layer can be laminated thereon, and examples thereof include paper, cloth, wood, glass, metal, and resin. The substrate may also be made of a plurality of materials. The shape of the substrate is not particularly limited, and the substrate may be a sheet or a flat plate, or may be a three-dimensional object of various shapes. If the surface of the substrate on which the image is formed is made of an inorganic material or a resin material having a glass transition point of 90° C. or higher, it is preferable because an image without bleeding is formed. Examples of inorganic materials include glass and metal. Examples of resin materials having a glass transition point (Tg) of 90° C. or higher include polymethylmethacrylate (Tg=90° C.), polystyrene (Tg=100° C.), polyacrylonitrile (Tg=104° C.), polyacrylic acid (Tg=106° C.), polycarbonate (Tg=150° C.), polymethacrylic acid (Tg=185° C.), and copolymers thereof.

[0025] In the resin layer forming process, a resin liquid containing a resin component that polymerizes when irradiated with ultraviolet light is ejected from an inkjet head and adhered to the substrate, and the resin component is fixed to the substrate as a resin layer by irradiating with ultraviolet light.

[0026] The resin component that is polymerized by ultraviolet irradiation may be a known one. Examples of known resin components include polymerizable oligomers such as epoxy acrylate, polyester urethane acrylate, and polyester acrylate, polymerizable monomers such as 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate, acetophenone, 2,2-diethoxyacetophenone, benzophenone, Michler's ketone, benzil, benzoin alkyl ether, benzil methyl ketal, and thioxane. One or more of these resin components are selected, and the resin liquid is prepared by appropriately adjusting the glass transition point of the resin layer after polymerization by ultraviolet irradiation to a predetermined range. The resin liquid contains a photopolymerization initiator and a surfactant, etc., as necessary. The glass transition point of the resin layer is preferably in the range of 0°C to 70°C, more preferably in the range of 25°C to 55°C, more preferably in the range of 38°C to 55°C, and particularly preferably in the range of 49°C to 55°C. If the glass transition point of the resin layer is within the above range, the transfer sheet has excellent peelability in the transfer process.

[0027] The resin layer formed by the resin component polymerized by ultraviolet irradiation may be composed of multiple resin layers. The multiple resin layers may be, for example, two or three layers. When the resin layer is two layers (a base layer and a surface layer), the glass transition point of the base layer is preferably less than 25°C, and particularly preferably less than 16°C. If the glass transition point of the base layer is within the above range, the adhesion between the substrate and the base layer is good.

[0028] The glass transition point of the surface layer is preferably within a range of 25° C. to 55° C., more preferably within a range of 38° C. to 55° C., and particularly preferably within a range of 49° C. to 55° C. If the glass transition point of the surface layer is within the above range, the transfer sheet has excellent releasability in the transfer step.

[0029] When the resin layer is three layers (base layer, intermediate layer, surface layer), the resin component forming the intermediate layer may be the same as the resin component forming the surface layer. In addition, the resin liquid forming the intermediate layer may contain a coloring material, and the resin liquid forming the base layer and the surface layer may not contain a coloring material. In addition, when the resin layer is two layers (base layer, surface layer), the resin liquid forming the base layer may contain a coloring material. The coloring material is preferably, for example, a white pigment, but is not limited to white. As a result, the base layer has good adhesion to the substrate, the surface layer has good peelability of the transfer sheet, and the intermediate layer or base layer is colored, so that the image transferred to the surface layer has good color development.

[0030] Examples of white pigments include zinc oxide, which is CI Pigment White (hereinafter also referred to as "CIPW") 4, titanium oxide, which is CIPW6, zinc sulfide, which is CIPW7, zirconium oxide (zirconium white), which is CIPW12, calcium carbonate, which is CIPW18, aluminum oxide / silicon oxide (kaolin clay), which is CIPW19, barium sulfate, which is CIPW21 or 22, aluminum hydroxide (alumina white), which is CIPW23, silicon oxide, which is CIPW27, and calcium silicate, which is CIPW28. The inorganic particles used for the white pigment may be a single particle, or may be a composite particle with an oxide of silicon, aluminum, zirconium, titanium, or the like, an organic metal compound, or an organic compound. Among them, titanium oxide has a smaller specific gravity and a larger refractive index than other white pigments, and therefore has excellent hiding power and coloring properties for the substrate, and is also excellent in durability against acids, alkalis, and other environments, and is therefore preferably used. In addition to titanium oxide, other white pigments (which may be other than the above-mentioned white pigments) may be used in combination.

[0031] Each resin liquid is discharged from an inkjet head toward the substrate, and is attached to the substrate or an already formed resin layer. A known inkjet head that discharges minute droplets from a nozzle is used. The resin liquid may be applied so as to cover the entire substrate or resin layer, or may be applied only to a part of the substrate. Then, the resin liquid is applied to the substrate or resin layer, and is irradiated with ultraviolet light to harden the resin component, thereby forming a resin layer. When multiple resin layers are formed, for example, the discharge of the resin liquid by the inkjet head and the irradiation of ultraviolet light are repeated in sequence for the base layer, intermediate layer, and surface layer.

[0032] The thickness of the resin layer is preferably in the range of 5 μm to 50 μm as a whole, more preferably in the range of 10 μm to 50 μm, and even more preferably in the range of 43 μm to 50 μm. If the thickness of the resin layer is within the above range, the color development of the image is good.

[0033] In addition, when the resin layer is composed of a plurality of layers, the thickness of the surface layer is preferably within the range of 15 μm to 45 μm. If the thickness of the surface layer is within the above range, the color development of the image is good and the texture of the base material is maintained.

[0034] In the transfer step, a transfer sheet having a sublimation dye ink layer is attached to the resin layer, and the sublimation dye ink of the sublimation dye ink layer is transferred to the resin layer by heating. After the transfer, the transfer sheet is peeled off from the resin layer.

[0035] The transfer sheet having a sublimation dye ink layer is formed by a known method. Examples of the substrate of the transfer sheet include paper and resin. The dye ink is ejected onto the substrate sheet by an inkjet head or the like to form a sublimation dye ink layer of a desired image. The dye ink contains a disperse dye that sublimes when heated, and dye inks of multiple colors may be used.

[0036] The sublimation dye ink contains water, a water-soluble organic solvent, and a sublimation dye. The sublimation dye is also called a disperse dye. Examples of the sublimation dye include CI Disperse Red 60; CI Disperse Yellow 3, 7, 8, 23, 39, 51, 54, 60, 71, 86; CI Disperse Orange 1, 1:1, 5, 20, 25, 25:1, 33, 56, 76; CI Disperse Brown 2; CI Disperse Red 11, 50, 53, 55, 55:1, 59, 60, 65, 70, 75, 93, 146, 158, 190, 190 :1, 207, 239, 240; CI Bat Red 41; CI Disperse Violet 8, 17, 23, 27, 28, 29, 36, 57; CI Disperse Blue 19, 26, 26:1, 35, 55, 56, 58, 64, 64:1, 72, 72:1, 81, 81:1, 91, 95, 108, 131, 141, 145, 359; CI Solvent Blue 36, 63, 105, 111; and the like. These may be used alone or in combination of two or more. The dye ink may also contain components (other components) other than those described above. Examples of other components include dispersants, antiseptics and fungicides, pH adjusters, chelating agents, rust inhibitors, ultraviolet absorbers, defoamers, and surface tension adjusters.

[0037] The heating temperature when transferring the dye ink to the resin layer is preferably within the range of 120°C to 240°C. If the heating temperature is lower than the above range, the transfer efficiency will be poor. If the heating temperature is higher than the above range, the image will be blurred or the resin layer will be altered, affecting the image. The transfer time is not particularly limited, but is, for example, 30 seconds. EXAMPLES

[0038] Examples of the present invention will now be described.

[0039] Example 1 Resin solution A, which was adjusted so that the glass transition point of the resin layer polymerized by ultraviolet irradiation was 38°C, was sprayed onto a glass plate in a rectangle of 20 mm x 50 mm using an inkjet printer (Brother Industries, GTX pro), and a resin layer with a thickness of 15 μm was formed by irradiating ultraviolet rays. A transfer sheet in which a sublimation dye ink (CI Disperse Red 60) was laminated on a paper sheet was placed on the formed resin layer, and heated at 160°C for 30 seconds using a manual small iron press machine Kabuto PCA-3233. After natural cooling, the transfer sheet was peeled off from the resin layer to form a rectangular fill-in image on the substrate. That is, the sublimation dye ink was sublimated and transferred from the transfer sheet to the resin layer. The glass transition point of the resin layer was measured using an irradiation differential scanning calorimeter DSC7000X (Hitachi High-Tech Corporation).

[0040] Example 2 An image was formed in the same manner as in Example 1, except that resin liquid B was used, which was adjusted so that the glass transition point of the resin layer polymerized by ultraviolet irradiation was 27°C, and the thickness of the resin layer was 20 μm.

[0041] Example 3 An image was formed in the same manner as in Example 2, except that the thickness of the resin layer was 10 μm.

[0042] Example 4 An image was formed in the same manner as in Example 2, except that the thickness of the resin layer was 50 μm.

[0043] Example 5 The glass transition point of the resin layer polymerized by ultraviolet irradiation was adjusted to 50°C. Resin liquid C containing CIPW6 (titanium oxide) was used, and an image was formed in the same manner as in Example 1, except that the thickness of the resin layer was 10 μm.

[0044] Example 6 Resin solution E, which was adjusted so that the glass transition point of the resin layer polymerized by ultraviolet irradiation was 21°C, was sprayed onto a flat glass plate in a rectangle of 20mm x 50mm using an inkjet printer (Brother Industries, GTX pro), and a base layer with a thickness of 3μm was formed by irradiating ultraviolet rays. Furthermore, resin solution D, which was adjusted so that the glass transition point of the resin layer polymerized by ultraviolet irradiation was 49°C, was attached to the base layer using an inkjet printer and irradiated with ultraviolet rays to form a surface layer with a thickness of 10μm. Thereafter, an image was formed using a transfer sheet in the same manner as in Example 1.

[0045] Example 7 Resin solution F, which was adjusted so that the glass transition point of the resin layer polymerized by ultraviolet irradiation was 15°C, was sprayed onto a flat glass plate in a rectangle of 20 mm x 50 mm using an inkjet printer (Brother Industries, GTX pro), and a base layer with a thickness of 3 μm was formed by irradiating ultraviolet rays. Furthermore, resin solution A was attached to the base layer using an inkjet printer and irradiated with ultraviolet rays to form a surface layer with a thickness of 10 μm. Thereafter, an image was formed using a transfer sheet in the same manner as in Example 1.

[0046] Example 8 An image was formed in the same manner as in Example 6, except that resin liquid D was applied to the base layer using an inkjet printer (Brother Industries, GTX pro) and then irradiated with ultraviolet light to form a surface layer with a thickness of 15 μm.

[0047] Example 9 An image was formed in the same manner as in Example 8, except that the thickness of the surface layer was set to 20 μm.

[0048] Example 10 Resin liquid F was sprayed onto a metal plate in a 20 mm x 50 mm rectangle using an inkjet printer (Brother Industries, GTX pro), and a base layer with a thickness of 3 μm was formed by irradiating it with ultraviolet light. Furthermore, resin liquid D was attached to the base layer using an inkjet printer, and a surface layer with a thickness of 40 μm was formed by irradiating it with ultraviolet light. Thereafter, an image was formed using a transfer sheet in the same manner as in Example 1.

[0049] Example 11 Resin liquid E was sprayed onto a metal plate in a 20 mm x 50 mm rectangle using an inkjet printer (Brother Industries, GTX pro), and a base layer with a thickness of 1 μm was formed by irradiating ultraviolet rays. Furthermore, resin liquid G, which was adjusted so that the glass transition point of the resin layer polymerized by ultraviolet irradiation was 52 ° C., was attached to the base layer using an inkjet printer and irradiated with ultraviolet rays to form a surface layer with a thickness of 20 μm. Thereafter, using the same transfer sheet as in Example 1, the transfer sheet was heated at 90 ° C. for 30 seconds, and after natural cooling, the transfer sheet was peeled off from the resin layer to form a rectangular fill-in image on the substrate.

[0050] Example 12 An image was formed in the same manner as in Example 11, except that the heating temperature for the transfer sheet was 250°C.

[0051] Example 13 Resin liquid E was sprayed onto a flat plate made of polycarbonate (Tg=150°C) in a rectangle of 20mm x 50mm using an inkjet printer (Brother Industries, GTX pro), and a base layer with a thickness of 1 μm was formed by irradiating ultraviolet rays. Furthermore, resin liquid G was attached to the base layer using an inkjet printer and irradiated with ultraviolet rays to form a surface layer with a thickness of 20 μm. Thereafter, using a transfer sheet similar to that in Example 1, the substrate was heated at 160°C for 30 seconds, and after natural cooling, the transfer sheet was peeled off from the resin layer to form a rectangular fill-in image on the substrate.

[0052] Example 14 An image was formed in the same manner as in Example 7, except that a vinyl chloride (Tg=87° C.) flat plate was used as the substrate.

[0053] Example 15 An image was formed in the same manner as in Example 7, except that resin liquid C was applied to the base layer using an inkjet printer (Brother Industries, GTX pro) and then irradiated with ultraviolet light to form a surface layer with a thickness of 10 μm.

[0054] (Example 16) Resin liquid C was sprayed onto a flat glass plate in a rectangular shape of 20 mm x 50 mm using an inkjet printer (GTX pro, manufactured by Brother Industries, Ltd.), and a base layer with a thickness of 10 μm was formed by irradiating it with ultraviolet light. Furthermore, resin liquid D was attached to the base layer using an inkjet printer, and a surface layer with a thickness of 10 μm was formed by irradiating it with ultraviolet light. Thereafter, an image was formed using a transfer sheet in the same manner as in Example 1.

[0055] (Example 17) Resin liquid F was sprayed onto a flat glass plate in a rectangle of 20 mm x 50 mm using an inkjet printer (Brother Industries, GTX pro), and a base layer with a thickness of 3 μm was formed by irradiating ultraviolet rays. Furthermore, resin liquid C was attached to the base layer using an inkjet printer and irradiated with ultraviolet rays to form an intermediate layer with a thickness of 3 μm. Furthermore, resin liquid D was attached to the intermediate layer using an inkjet printer and irradiated with ultraviolet rays to form a surface layer with a thickness of 10 μm. Thereafter, an image was formed using a transfer sheet in the same manner as in Example 1.

[0056] Comparative Example 1 Resin liquid B, which further contained a magenta pigment (PR122), was sprayed onto a 20 mm x 50 mm rectangle on a glass plate using an inkjet printer (Brother Industries, GTX pro), and a rectangular filled-in image was formed by irradiating it with ultraviolet light.

[0057] Comparative Example 2 An image was formed in the same manner as in Comparative Example 1, except that the thickness of the resin layer was 100 μm.

[0058] Comparative Example 3 A solid image was formed by spraying the ink for sublimation transfer directly onto a 20mm x 50mm rectangle on a glass plate using an inkjet printer (Brother Industries, GTX pro) and sublimating it. The sublimation conditions were 200°C and 30 seconds. In other words, sublimation transfer using a transfer sheet was not performed.

[0059] Comparative Example 4 Resin liquid F was sprayed onto a glass plate in a 20 mm x 50 mm rectangle using an inkjet printer (Brother Industries, GTX pro), and a base layer with a thickness of 5 μm was formed by irradiating it with ultraviolet light. Furthermore, resin liquid B was sprayed onto the base layer using an inkjet printer, and a surface layer with a thickness of 20 μm was formed by irradiating it with ultraviolet light. A solid image was formed by directly spraying sublimation transfer ink onto the surface layer using an inkjet printer and sublimating it. The sublimation conditions were 200°C and 30 seconds. In other words, sublimation transfer using a transfer sheet was not performed.

[0060] [Color development test] The optical density (OD value) of three points in the formed image was measured using a spectrophotometer SpectoroEye manufactured by X-Rite (light source: D50, viewing angle: 2°, ANSI-T), the average value was calculated, and the image was evaluated according to the following evaluation criteria. AA: 2.0 or higher A: 1.5 or more and less than 2.0 B: 1.0 or more and less than 1.5 C: Less than 1.5 or no color development

[0061] [Bleeding test] The occurrence of bleeding in the formed image was visually observed and judged according to the following evaluation criteria. A: No bleeding at all B: There is a little bleeding. C: There is bleeding

[0062] [Peeling test] When an image was formed using the transfer sheet, the peelability of the transfer sheet was evaluated according to the following criteria. AA: Easily peelable A: Some peeling marks remain on the resin layer. B: Many peeling marks remain on the resin layer C: Cannot be peeled off

[0063] [Adhesion test] A cellophane tape (CT-12, manufactured by Nichiban) was firmly adhered to the surface of the resin layer, and when it was quickly peeled off, the remaining rate of the resin layer was visually judged according to the following criteria. AA: 90% or more of the resin layer remained A: More than 70% of the resin layer remained. B: More than 50% of the resin layer remained C: Less than 50% of the resin layer remained.

[0064] [Texture test] The imaged substrate was visually inspected for the presence or absence of texture. ○: The texture of the base material remains ×: The texture of the base material is not retained

[0065] [Substrate color concealment test] It was visually judged whether the color of the substrate on which the image was formed was concealed.

[0066] [Color development test evaluation] As shown in Tables 1 to 3, Examples 1 to 17 have superior color development compared to Comparative Examples 1 and 4. Examples 2, 4, 8 to 10, 13, 16, and 17, in which the total thickness of the resin layers is 16 μm or more, are evaluated as A or higher and have superior color development.

[0067] [Bleeding test evaluation] It can be seen that Examples 1 to 13 and 15 to 17, in which the substrate material is glass, metal, or polycarbonate (Tg=150° C.), have less bleeding than Example 14, in which the substrate material is polyvinyl chloride (Tg=87° C.).

[0068] [Peeling test evaluation] It can be seen that Examples 1, 5 to 17, in which the surface layer has a glass transition point (Tg) of 38° C. or higher, have excellent releasability of the transfer sheet compared to Examples 2 to 4, in which the surface layer has a glass transition point (Tg) of 27° C. If the surface layer has a high glass transition point, the surface layer is hard and has low adhesive strength, and therefore it is believed that the transfer sheet has excellent releasability. If the surface layer has a low glass transition point, the surface layer is soft and has high adhesive strength, and therefore it is believed that the transfer sheet has poor releasability.

[0069] [Adhesion test evaluation] Among Examples 6 to 17 in which the resin layer is two or three layers, Examples 6 to 15 and 17 in which the glass transition point of the base layer is lower than that of the surface layer are superior in adhesion of the resin layer to the substrate, compared with Example 16 in which the glass transition point of the base layer is higher than that of the surface layer. The resin layer polymerized by UV irradiation is in a state in which internal stress is generated due to shrinkage caused by polymerization. It is considered that the adhesion is inferior when the thickness of the resin layer increases because the internal stress increases. In addition, when the glass transition point of the base layer is higher than that of the surface layer, the crosslinking density, which is correlated with the glass transition point, increases, and as a result, the adhesion is inferior.

[0070] [Texture test evaluation] It can be seen that in Examples 1 to 17, in which the total thickness of the resin layers is 10 μm to 50 μm, the texture of the substrate is maintained, compared to Comparative Example 2, in which the total thickness of the resin layers is 100 μm. In addition, in Examples 1 to 17, the resin layers are selectively sprayed onto the substrate by an inkjet head, so that the equipment is smaller than that of conventional powder coating. In addition, since the resin layers can be selectively formed on the substrate, the texture of the substrate can be preserved. In addition, the resin liquid is efficiently used only in the necessary places.

[0071] [Concealment test evaluation of substrate color] It is seen that Examples 5, 15 to 17, in which the resin liquid forming the resin layer contains a pigment, conceal the color of the substrate. By concealing the color of the substrate, a resin layer is formed only in the area where an image is to be formed on a dark-colored substrate, and the image can be sublimation transferred. It is also seen that, among Examples 5, 15 to 17, Examples 16 and 17, in which the resin liquid forming the surface layer does not contain a pigment, have superior color development compared to Examples 5 and 15, in which the resin liquid forming the surface layer contains a pigment.

[0072] [Table 1] [Table 2] [Table 3]

Claims

1. 1. A method for forming an image on a substrate, comprising: a resin layer forming step of depositing a resin liquid containing a resin component that polymerizes when irradiated with ultraviolet light onto the substrate from an inkjet head, and then fixing the resin component to the substrate as a resin layer by irradiating ultraviolet light; a transfer step of adhering a transfer sheet having a sublimation dye ink layer to the resin layer and transferring the sublimation dye ink of the sublimation dye ink layer to the resin layer by heating.

2. 2. The image forming method according to claim 1, wherein the substrate contains an inorganic material or a resin material having a glass transition point of 90[deg.] C. or higher.

3. 3. The image forming method according to claim 1, wherein the resin layer has a glass transition temperature within the range of 0°C to 70°C.

4. 3. The image forming method according to claim 1, wherein the resin layer has a thickness in the range of 5 to 50 [mu]m.

5. The resin liquid includes a first resin liquid including a first resin component and a second resin liquid including a second resin component, The resin layer forming step includes: a first step of depositing the first resin liquid on the substrate by ejecting it from an inkjet head, and fixing the first resin component to the substrate as a base layer by irradiating the substrate with ultraviolet light; a second step of depositing the second resin liquid by ejecting it from an inkjet head, and laminating the second resin component as a surface layer on the base layer by irradiating it with ultraviolet light; 3. The image forming method according to claim 1, wherein the glass transition point of the base layer is lower than the glass transition point of the surface layer.

6. The image forming method according to claim 5 , wherein the first resin liquid contains a coloring material.

7. The base layer has a glass transition temperature of less than 25° C.

6. The image forming method according to claim 5, wherein the surface layer has a glass transition temperature within a range of 25[deg.] C. to 55[deg.] C.

8. 8. The image forming method according to claim 7, wherein the surface layer has a thickness of 15 [mu]m or more.

9. The resin liquid further includes a third resin liquid containing the resin component, The third resin liquid contains a color material, The first resin liquid and the second resin liquid do not contain a color material, The resin layer forming step includes:

6. The image forming method according to claim 5, further comprising a third step, which is performed after the first step and before the second step, of depositing the third resin liquid by ejecting it from an inkjet head and irradiating it with ultraviolet light to form an intermediate layer between the base layer and the surface layer.

10. 3. The image forming method according to claim 1, wherein the heating temperature when the sublimation dye ink of the sublimation dye ink layer is transferred to the resin layer in the transfer step is within a range of 120°C to 240°C.

Images