Image formation method

Abstract

To provide an image formation method that solves a problem that the conventional method of foil transfer using the adhesive power of a toner image has the advantage of not using a mold, which is required for foil stamping, in which an electrostatic latent image (static electricity pattern) is first formed on a photoconductor of a copier, which is developed into a toner image, and the toner image is then transferred onto a transfer material or transfer foil, and after that, the foil transfer is performed, however, since the photoconductor has analog characteristics and the electrostatic latent image does not have high resolution, it is not possible to form a high-resolution toner image, and as a result, it is difficult to form a high-definition image on the transfer material.SOLUTION: Without using a photoreceptor, an electrostatic pattern is formed directly on a release layer of a substrate consisting of a release layer, an insulating layer, and a conductive layer, and this electrostatic pattern is developed with charged particles called toner to form a high-resolution toner image on the release layer, which is then transferred onto any substrate that becomes the transfer target. After a transfer foil is attached to this toner image, heat and pressure are applied so that a high-definition image is formed on the substrate.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an image forming method, and more particularly to an image forming method utilizing foil transfer. [Background technology]

[0002] In the fields of commercial printing, card business, and plastic molding of cosmetic containers, etc., foil transfer products are manufactured using a processing method called foil stamping. This processing method is also called hot stamping, in which a mold with a predetermined character or image equipped with a heated plate is pressed against the transfer foil, and the characters or image made of foil are transferred to the surface of the transfer target (the base material that will become the foil transfer target) by the action of heat and pressure, and the transfer target can be given a metallic feel (metallic luster) and unique color that cannot be obtained by general printing. However, this method requires a mold for the desired characters or images and large-scale equipment for the transfer process. As a method for manufacturing foil transfer products that does not use a mold, a method has been proposed in which the adhesive force of a toner image obtained by developing an electrostatic latent image (static electricity pattern) on the photoconductor of a copier is used to perform foil transfer only in the area of ​​the toner image.

[0003] For example, a toner image is formed on the release layer of a heat-resistant film by a copier, and then the toner image is transferred onto the adhesive layer of a transfer foil. There is a method in which the transfer foil is placed on the transferee, and heat and pressure are applied again from above to perform foil transfer only on the toner image portion (see Patent Document 1). There is also a method in which a toner image is attached to the transferee by a copier, a vapor-deposited foil sheet is placed on top of it, and after hot pressing from above with an iron, the vapor-deposited foil sheet is simply peeled off to perform foil transfer (see Patent Document 2). Furthermore, the toner image on the photoreceptor is transferred and fixed on the transferee to form a foil transfer surface (toner image area). There is an image formation method in which the foil transfer surface is brought into contact with the transfer foil, and in this state, the foil is transferred to the foil transfer surface by passing through a nip portion formed by a drive roller and a driven roller whose end outer diameter is larger than the outer diameter of the other portions (see Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 3-221486 [Patent Document 2] JP 2000-127691 A [Patent Document 3] JP 2012-145622 A Summary of the Invention [Problem to be solved by the invention]

[0005] The method of performing foil transfer only on the toner image portion by utilizing the adhesive force of the toner image allows foil transfer without using a metal mold required for foil stamping, making it possible to improve the efficiency of foil transfer work and simplify the foil transfer device. In all of these methods, an electrostatic latent image (static electricity pattern) is first formed on the photoconductor of a copying machine, which is developed with dry toner to form a toner image, and the toner image is then transferred onto a transfer object or transfer foil, after which foil transfer is performed. However, since the photoconductor has analog characteristics and the electrostatic latent image does not have high resolution, a high-resolution toner image cannot be formed, and as a result, it has been difficult to form a high-definition image on the transfer object.

[0006] The present invention proposes an image forming method for solving the above problems. [Means for solving the problem]

[0007] The inventors have discovered that, without using a photoconductor, an electrostatic pattern can be formed directly on the release layer of a substrate consisting of a release layer, an insulating layer, and a conductive layer, and this electrostatic pattern can be developed with charged particles called toner to form a high-resolution toner image on the release layer, and that this toner image can be transferred to any substrate as a receiving body, and that a high-definition image can be obtained on any substrate by adhering a transfer foil to the toner image and then applying heat and pressure, thereby arriving at the present invention.

[0008] The present invention provides an image forming method which solves the above problems. (I) (1) a step of forming a static electricity pattern on a release layer of a substrate S, the release layer including an insulating layer and a conductive layer (a static electricity pattern forming step); (2) developing the electrostatic pattern with charged particles called toner to form a toner image on the release layer of the substrate S (developing step); (3) a step of transferring the toner image onto a substrate T (toner transfer step); (4) A process (foil transfer process) in which a transfer foil having a transfer layer F consisting of three layers, a release layer, a protective layer, and a metal layer, or a transfer layer G consisting of two layers, a release layer and a color layer, provided on a heat-resistant film and the substrate T is used, and the transfer layer F or the transfer layer G is brought into close contact with the toner image on the substrate T, and then heat and pressure are applied to transfer at least the protective layer and the metal layer of the transfer layer F, or at least the color layer of the transfer layer G, onto the toner image on the substrate T; (5) An image forming method comprising a step of separating the transfer foil from the substrate T (transfer foil separating step). (II) The image forming method described in item 1 above, characterized in that an original plate having a printing layer on which a letterpress, intaglio, or gravure-like pattern is formed and a first electrode, and a substrate S having a release layer, an insulating layer, and a conductive layer that serves as a second electrode are used, the printing layer of the original plate and the release layer of the substrate S are brought into close contact with each other, and an appropriate voltage is applied between the first electrode of the original plate and the second electrode of the substrate S sufficient to discharge the gap between the pattern of the printing layer and the release layer, thereby forming an electrostatic pattern corresponding to the pattern of the printing layer on the release layer of the substrate S. (III) The image forming method described in item 1 above, characterized in that a substrate S is used, which is made of a molded body of only a conductive material or a laminate of an insulating material and a conductive material and is provided with a mask sheet having a predetermined ion permeable opening, a release layer, an insulating layer, and a conductive layer that serves as a back electrode, and the mask sheet and the release layer of the substrate S are brought into close contact with each other, ions are irradiated through the mask sheet, and then the mask sheet is peeled off from the substrate S, thereby forming a static electricity pattern on the release layer of the substrate S corresponding to the ion permeable openings and ion shielding parts of the mask sheet. (IV) The image forming method described in the above item 3, wherein the ion irradiation means is an ion irradiation method using corona discharge. Effect of the Invention

[0009] In the method of the present invention, instead of using a photoreceptor as in the conventional technology, an electrostatic pattern is formed directly on the release layer of a substrate consisting of a release layer, an insulating layer, and a conductive layer, and this electrostatic pattern is developed with charged particles called toner to form a high-resolution toner image, which is then transferred onto any substrate to be transferred. A high-resolution image can be formed on any substrate by performing foil transfer using the adhesive force of this toner image. Moreover, the transfer of the toner image onto any substrate and the foil transfer onto the toner image can be repeated. [Brief description of the drawings]

[0010] [Figure 1] Static electricity pattern formation process [Diagram 2] Development process [Diagram 3] Toner transfer process [Figure 4] Foil transfer process [Diagram 5] Transfer foil separation process [Figure 6] Example of forming images on both sides of a substrate [Figure 7] An example of a static electricity pattern formation process [Figure 8] Another example of the static electricity pattern formation process DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] FIG. 1 shows the static electricity pattern forming step of the present invention, in which a static electricity pattern is formed on a release layer 23 of a substrate S and is held thereon. The substrate S is composed of a conductive layer 21, an insulating layer 22, and a release layer 23, which serve as electrodes in the static electricity pattern forming process. The insulating layer 22 must have high electrical insulation because it must retain the electrostatic pattern. Molded products such as polyimide, polycarbonate, PET (polyethylene terephthalate), cycloolefin polymer, cycloolefin copolymer, and fluorine-based resin can be used as the insulating layer 22. The thickness of the insulating layer 22 is preferably 5 to 200 μm. If the thickness is less than 5 μm, handling is difficult. If the thickness exceeds 200 μm, the rigidity becomes high, making it difficult to bring the toner image on the substrate S into close contact with the substrate T to perform toner transfer.

[0012] In order to facilitate the transfer of the toner image 24 on the substrate S onto the substrate T, a release layer 23 is provided on the insulating layer 22. A thin film of a silicone resin, a fluorine resin, an olefin resin, a melamine resin, or the like formed by a coating method or the like can be used as the release layer 23. The thickness of the release layer is preferably 0.03 to 0.4 μm.

[0013] The conductive layer 21 only needs to serve to supply an electric field in the electrostatic pattern formation process or to stabilize the charge on the release layer 23, and may be made of any conductive material, such as a metal, a conductive oxide, carbon, graphite, or a conductive polymer. The conductive layer 21 is disposed on the surface of the insulating layer 22 opposite the release layer 23. The conductive layer 21 can fulfill the above-mentioned role if it is pressed against the insulating layer 22, but if it is integrated with the release layer 23 and the insulating layer 22, it becomes easier to handle in the static electricity pattern forming process and the development process. If the conductive layer 21 is formed on the surface of the insulating layer 22 opposite the release layer 23 by a method such as sputtering a metal film or a conductive oxide film, coating a conductive polymer film, or laminating a metal foil, the release layer 23, the insulating layer 22, and the conductive layer 21 can be integrated. Conversely, the release layer 23, the insulating layer 22, and the conductive layer 21 can be integrated by providing the insulating layer 22 and the release layer 23 on the conductive layer 21 made of metal foil or the like by a coating method or the like. Alternatively, a sheet with a conductive layer, which has a conductive layer 21 such as a metal film, a conductive oxide film, or a conductive polymer film already provided on an insulating material sheet, can be laminated to the side of the insulating layer 22 opposite the release layer 23 using an adhesive layer, thereby integrating the release layer 23, the insulating layer 22 and the conductive layer 21.

[0014] An example of the electrostatic pattern formation process is shown in FIG. 7. This method is an application of the high-definition electrostatic printing method proposed by the present inventors (see the specification of Japanese Patent Application No. 2018-188998). Using an original plate 10 having a plate layer 12 on which a relief, intaglio, or gravure-like pattern is formed (FIG. 7 shows an example in which the portion where a toner image is formed is intaglio) and a first electrode 11, and a substrate S having a release layer 23, an insulating layer 22, and a conductive layer 21 that becomes a second electrode, the plate layer 12 of the original plate 10 and the release layer 23 of the substrate S are closely attached to each other, and an appropriate voltage is applied between the first electrode 11 of the original plate 10 and the second electrode 21 of the substrate S to discharge the gap between the pattern of the plate layer 12 and the release layer 23, thereby forming an electrostatic pattern corresponding to the pattern of the plate layer 12 on the release layer 23.

[0015] The conditions under which a gap discharges can be calculated using Paschen's law. The discharge inception voltage for gaps of 8 μm or more can be expressed as a straight line, and is approximated by the following formula, where gap: d (μm) and gap discharge inception voltage: Vb. Vb=312+6.2d (1) The gap (the gap between the pattern of the printing layer 12 and the release layer 23) is 20 μm, and the discharge start voltage is 436 V. In other words, when an external voltage of 436 V or more is applied to the gap, a discharge occurs and ions are generated. The generated ions move in the electric field, with positive ions moving toward the negative electrode and positive ions moving toward the negative electrode. The ions charge the release layer 23, which acts to weaken the electric field in the gap. The discharge ends when the voltage applied to the gap reaches the discharge start voltage of 436 V.

[0016] In the example of FIG. 7, the insulating layer 22 is PET with a thickness of 25 μm and a relative dielectric constant of 3.2, and when converted to an air thickness, the thickness is 25÷3.2=7.8. The thickness of the release layer 23 is less than 0.5 μm, so it can be practically ignored. In this example, the entire surface of the release layer 23 is pre-charged with +300 V. This pre-charge process ensures that the substrate S adheres to the original plate 10. With the plate layer 12 and the release layer 23 in close contact, the second electrode 21 is set to ground potential, and a voltage is applied so that −723 V is applied to the first electrode 11. The voltage applied to the 20 μm gap is (723+300)×20÷(20+7.8)V=736V. Since this is greater than the discharge start voltage of 436 V for a 20 μm gap obtained from formula (1), discharge ions are generated in the gap, negative ions move toward the electrode 21 and charge the release layer 23, and positive ions flow to the electrode 11. When the release layer 23 is charged to -(736-436) = -300V, the electric field applied to the gap reaches the discharge start voltage of 436V, and the discharge stops. Thereafter, the applied power is turned off and the electrode 21 is set to 0V before the substrate S is peeled off from the original 10. This results in a static electricity pattern in which the areas on the release layer 23 that correspond to the gaps of the intaglio (areas where the toner image is formed) are charged to -300V and the other areas are charged to +300V. The reason that the electrode 21 is set to 0V before peeling is to create conditions in which no part of the entire surface will discharge due to peeling.

[0017] Another example of the electrostatic pattern formation process is shown in FIG. 8. This method is an application of the electrostatic printing method proposed by the present inventors (see the specification of Japanese Patent Application No. 2021-132875). A substrate S is used, which is made of a molded body of only a conductive material or a laminate of an insulating material and a conductive material and has a predetermined ion-permeable opening, a release layer 23, an insulating layer 22, and a conductive layer 21 that becomes a back electrode, and the mask sheet M and the release layer 23 of the substrate S are adhered to each other, ions are irradiated through the mask sheet M, and then the mask sheet M is peeled off from the substrate S to form a static electricity pattern on the release layer 23 of the substrate S, which corresponds to the ion-permeable opening and ion shielding portion of the mask sheet M.

[0018] In the example of FIG. 8, a conductive layer 21, which becomes a back electrode, is adhered to the surface of the insulating layer 22 opposite to the release layer 23, and the conductive layer 21 is grounded. Before the mask sheet M is adhered to the release layer 23, a preliminary electrification process is performed on the entire surface of the release layer 23 at -300V. This preliminary electrification process ensures that the mask sheet M adheres to the release layer 23. With the mask sheet M having the ion permeable openings 31 adhered to the release layer 23, ions are irradiated through the mask sheet M by the ion irradiation means 40. After the ion irradiation, the surface of the mask sheet M and the ion irradiated parts corresponding to the ion permeable openings 31 of the release layer 23 are charged to +300V. With the mask sheet M grounded, it is peeled off from the release layer 23. The ion-irradiated areas (areas other than those where toner images are formed) corresponding to the ion-permeable openings 31 of the release layer 23 are charged to +300 V, and the non-ion-irradiated areas (areas where toner images are formed) corresponding to the ion-shielding areas are charged to -300 V, creating a static electricity pattern.

[0019] Figure 2 shows the development process. The electrostatic pattern created in the electrostatic pattern formation process is developed with charged particles called toner. The liquid toner for electrophotography proposed by the present inventors can be used as the toner (see the specification of Japanese Patent Application No. 2019-209237). Liquid toners are advantageous in forming high resolution toner images as compared to dry toners. 2 shows an example in which a positively charged toner is used. The drying conditions immediately after development are 110°C for 3 minutes. In this case, the toner does not adhere to the parts of the release layer 23 that are charged to +300V (parts other than those where a toner image is formed), but adheres to the parts that are charged to -300V (parts where a toner image is formed), and a toner image 24 is formed on the release layer 23.

[0020] 3 shows the toner transfer process. After the toner image 24 is in intimate contact with the substrate T, heat and pressure are applied to transfer the toner image 24 onto the substrate T. In the example of FIG. 3, the toner image and the substrate T were in close contact with each other and passed between nip rolls having a surface temperature of 110° C., thereby transferring the toner image onto the substrate T. The substrate T may be made of any material as long as it has the surface properties (surface roughness, wettability index, etc.) and heat resistance required for the toner image to adhere thereto. Examples of such materials include molded products and laminates made of various types of plastics, glass, glass epoxy resin, ceramics, metals, etc. The substrate T may be subjected to surface treatment (plasma treatment, corona treatment, coating of an adhesive layer, etc.) to improve adhesion to the toner image. FIG. 3 shows an example in which the substrate T is a glass plate having a thickness of 0.5 mm.

[0021] Fig. 4 shows the foil transfer process. The transfer foil is a heat-resistant film (e.g., PET with a thickness of 12 μm) on which a transfer layer F consisting of three layers, namely, a release layer, a protective layer, and a metal layer (e.g., a thin film of aluminum, tin, copper, chromium, nickel, gold, etc.), or a transfer layer G consisting of two layers, namely, a release layer and a color layer, is provided. These are the basic configurations of the transfer foil of the present invention, but a transfer layer F or a transfer layer G may also be provided with an adhesive layer added to the outermost surface thereof. In this case, the adhesive layer is transferred together with the transfer layer. Using the transfer foil and the substrate T, the transfer layer and the toner image 24 on the substrate T are brought into close contact with each other, and then the transfer layer is transferred onto the toner image 24 on the substrate T by applying heat and pressure. In the example of Figure 4, the transfer layer and the toner image 24 on the substrate T were in close contact with each other and passed between nip rolls having a surface temperature of 110°C, thereby transferring the transfer layer onto the toner image 24 on the substrate T.

[0022] FIG. 5 shows the transfer foil separation process. Figure 5 shows an example in which a transfer foil was used in which the transfer layer consisted of three layers: a release layer, a protective layer, and a copper layer (thickness 40 nm). The image formed on the substrate T had a line width of 25 μm and a line spacing of 25 to 75 μm.

[0023] FIG. 6 shows an example in which a toner image is transferred to the opposite side of substrate T in the same manner, and then foil transfer is performed using a transfer foil having two transfer layers, a release layer and a color layer. In the method of the present invention, the transfer of a toner image onto a substrate T and the transfer of a foil onto the toner image can be repeatedly performed.

[0024] The present invention can be used in various industrial fields such as commercial printing, card business, plastic molding for cosmetic containers, etc., as well as electronics. [Explanation of symbols]

[0025] 10:Original version 11: 1st electrode 12: Plate layer S: Substrate S 21: Conductive layer 22: Insulating layer 23: Release layer 24: Toner image T: Substrate T M: Mask sheet 31: Ion-permeable opening 32: Ion shielding section 40: Ion irradiation means 50: Transfer foil 51: Heat-resistant film 52: Release layer 53:Protective layer 54: Metal layer 55: Color layer

Claims

1. (1) A step of forming a static electricity pattern on a release layer of a substrate S including a release layer, an insulating layer, and a conductive layer (a static electricity pattern forming step); (2) developing the electrostatic pattern with charged particles called toner to form a toner image on the release layer of the substrate S (developing step); (3) A step of transferring the toner image onto a substrate T (toner transfer step); (4) A process of using a transfer foil having a transfer layer F consisting of three layers, a release layer, a protective layer, and a metal layer, or a transfer layer G consisting of two layers, a release layer and a color layer, provided on a heat-resistant film, and the substrate T, bringing the transfer layer F or the transfer layer G into close contact with a toner image on the substrate T, and then applying heat and pressure to transfer at least the protective layer and the metal layer of the transfer layer F, or at least the color layer of the transfer layer G, onto the toner image on the substrate T (foil transfer process); (5) An image forming method comprising a step of separating the transfer foil from the substrate T (a transfer foil separating step).

2. The image forming method according to claim 1, further comprising the steps of: using an original plate having a plate layer on which a relief, intaglio or gravure-like pattern is formed and a first electrode; and a substrate S having a release layer, an insulating layer and a conductive layer which becomes the second electrode; bringing the plate layer of the original plate into close contact with the release layer of the substrate S; and applying an appropriate voltage between the first electrode of the original plate and the second electrode of the substrate S sufficient to discharge the gap between the pattern of the plate layer and the release layer, thereby forming an electrostatic pattern corresponding to the pattern of the plate layer on the release layer of the substrate S.

3. 2. The image forming method according to claim 1, further comprising the steps of: using a substrate S which is made of a molded body of only a conductive material or a laminate of an insulating material and a conductive material and which is provided with a mask sheet having a predetermined ion permeable opening; a release layer; an insulating layer; and a conductive layer which serves as a back electrode; bringing the mask sheet into close contact with the release layer of the substrate S; irradiating ions through the mask sheet; and then peeling the mask sheet from the substrate S, thereby forming a static electricity pattern on the release layer of the substrate S which corresponds to the ion permeable openings and ion shielding portions of the mask sheet.

4. 4. The image forming method according to claim 3, wherein the ion irradiation means is an ion irradiation method using corona discharge.

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