Metal image formation method

Abstract

To solve such a problem that a conventional method performing a foil transfer utilizing an adhesion force of a toner image has an advantage of not using a metal mold necessary for pressing a foil, this method forms an electrostatic latent image (an electrostatic image) on a photoreceptor of a copier, develops the electrostatic latent image to make a toner image, and performs a foil transfer after transferring the toner image on a body to be transferred or the transfer foil, but the photoreceptor has an analogue property and the electrostatic latent image does not have a high-resolution, and therefore the toner image with a high-resolution cannot be formed, consequently, it is difficult to manufacture a foil transfer object with a high-resolution.SOLUTION: An electrostatic pattern is directly formed on a release layer of a substrate not using a photoreceptor, the substrate being composed of the release layer, an insulator layer, and a conductive layer. A toner image with a high-resolution is formed by developing the electrostatic pattern with a plating-able charged particle that is called a toner, and then the toner image is transferred on an arbitrary substrate as a body to be transferred. A catalytic ability is provided to the toner image and a metal image with a high-resolution is formed on an arbitrary substrate by performing an electroless plating.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for forming metal images. [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 a method for forming a metal image to solve the above problems. [Means for solving the problem]

[0007] The inventors have discovered that, without using a photosensitive member, 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 that this electrostatic pattern can be developed with plateable charged particles known as toner to form a high-resolution toner image on the release layer, and that this toner image can be transferred onto any substrate to be used as a transfer target, and that by imparting catalytic ability to this toner image and subjecting it to electroless plating processing, a high-definition metal image can be obtained on any substrate, thereby arriving at the present invention.

[0008] The present invention provides a method for forming a metal image which overcomes 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 plateable 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 method for forming a metal image, comprising a step of imparting catalytic ability to the toner image on the substrate T and carrying out an electroless plating process (an electroless plating process). (II) A method for forming a metal image as described in item 1, 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) A method for forming a metal image as 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 which 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 portions of the mask sheet. (IV) The method for forming a metallic image as 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 plateable charged particles called toner to form a high-resolution toner image, which is then transferred onto any substrate to be transferred. By imparting catalytic activity to this toner image and subjecting it to electroless plating, a high-definition metal image can be formed on any substrate. Moreover, it is possible to repeatedly transfer the toner image onto any substrate, impart catalytic activity to the toner image, and perform electroless plating. [Brief description of the drawings]

[0010] [Figure 1] Static electricity pattern formation process [Diagram 2] Development process [Diagram 3] Toner transfer process [Figure 4] Electroless plating process [Diagram 5] Example of metal images formed on both sides of the substrate [Figure 6] An example of a static electricity pattern formation process [Figure 7] 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 24 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. 6. 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). An original plate 10 including a plate layer 12 on which a relief, intaglio, or gravure-like pattern is formed (FIG. 6 shows an example in which the portion where a toner image is formed is intaglio) and a first electrode 11, and a substrate S including a release layer 23, an insulating layer 22, and a conductive layer 21 that becomes a second electrode are used, and the plate layer 12 of the original plate 10 and the release layer 23 of the substrate S are brought into close contact with 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 on the release layer 23 corresponding to the pattern of the plate layer 12.

[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. 6, 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. 7. 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 the ion shielding portion of the mask sheet M.

[0018] In the example of FIG. 7, 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 plateable charged particles called toner. The electrophotographic liquid toner proposed by the present inventors can be used as a plateable toner (see the specification of Japanese Patent Application No. 2019-209237). Liquid toner is advantageous in forming high-resolution toner images compared to dry toner. This toner is composed of a resin with a ligand that incorporates metal to form a complex, and has the function of adsorbing catalytic metals or catalytic metal ions. 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] Figure 4 shows the electroless plating process. By immersing in a solution containing a catalytic metal, the catalytic metal is attached only onto the toner image 24, imparting catalytic activity. If the catalytic metal is adsorbed as an ion, depending on the situation, an additional process of reducing and metallizing it with hypophosphorous acid, formalin, etc. may be required. Examples of catalytic metals include palladium, copper, gold, and platinum. After the toner image 24 is provided with catalytic activity, an electroless plating process is carried out to form a metal image 50 on the toner image 24 . In the example of FIG. 4, the substrate T onto which the toner image 24 was transferred was treated with the following catalytic ability imparting liquid, electroless nickel plating bath or electroless copper plating bath.

[0022] [Catalyst activation solution, electroless nickel plating bath and electroless copper plating bath] The composition of the catalytic activity imparting solution is shown in the table below. TIFF2025013068000001.tif67117The composition of the electroless nickel plating bath is shown in the table below. TIFF2025013068000002.tif41116The composition of the electroless copper plating bath is shown in the table below. TIFF2025013068000003.tif48117

[0023] The substrate T onto which the toner image 24 was transferred was immersed in the catalytic ability imparting liquid at 40° C. for 5 minutes, and then washed with water at room temperature for 1 minute to impart catalytic ability to the toner image 24 . Next, the substrate T was immersed in an electroless nickel plating bath having a pH of 8.0 and a temperature of 70° C. for 10 minutes, and then washed with water, thereby forming a nickel image 50 on the toner image 24 . Alternatively, the above substrate T was immersed in an electroless copper plating bath at 25° C. for 12 minutes, and then washed with water at room temperature for 1 minute, thereby forming a copper image 50 on the toner image 24 . The nickel image and the copper image formed on the substrate T each had a thickness of 0.5 μm, a line width of 10 μm, and a line spacing of 10 to 30 μm.

[0024] FIG. 5 shows an example in which a toner image is transferred to the opposite side of the substrate T in the same manner, and then catalytic function is imparted and electroless plating is performed. In the method of the present invention, it is possible to repeatedly perform the transfer of a toner image onto a substrate T, the imparting of catalytic activity to the toner image, and the electroless plating treatment.

[0025] If necessary, the metal image formed by the electroless plating process may be subjected to an electroplating process to laminate the same or a different metal on the metal image. By performing such an electroplating process, it is possible to improve the strength, conductivity, and other properties of the entire metal image including the laminated portion.

[0026] 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]

[0027] 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: Metal image

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 plateable 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 method for forming a metal image, comprising a step of imparting catalytic activity to the toner image on the substrate T and carrying out an electroless plating process (an electroless plating process).

2. The method for forming a metal image as described in claim 1, characterized in that an original plate having a plate layer on which a relief, intaglio or gravure plate-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 are used, the plate 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 sufficient to discharge the gap between the pattern of the plate layer and the release layer is applied between the first electrode of the original plate and the second electrode of the substrate S, thereby forming an electrostatic pattern corresponding to the pattern of the plate layer on the release layer of the substrate S.

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

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