Thermal transfer ink recovery device

Abstract

To enable efficient and user-friendly recovery of the ink layer without requiring equipment that heats to high temperatures or the use of solvents, as a recycling method for thermal transfer ink ribbons.SOLUTION: A thermal transfer ink recovery device for separating and recovering ink from a thermal transfer ink ribbon including a substrate and a thermal transfer ink layer, the device comprising: a cooling section configured to cool the thermal transfer ink ribbon to 0°C or below; and a folding section configured to fold the thermal transfer ink ribbon; wherein the device enables efficient recovery of the thermal transfer ink in solid form with good workability.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a recovery device for separating and recovering thermal transfer ink from a substrate of a thermal transfer ink ribbon. [Background technology]

[0002] Thermal transfer ink ribbons, which have traditionally been used in thermal transfer printers, are made by applying a thermal transfer ink layer to a substrate such as PET (polyethylene terephthalate) film. When the thermal transfer printer is in use, the heat from the thermal head melts the thermal transfer ink layer, transferring it from the substrate to the target material. Therefore, used thermal transfer ink ribbons often have untransferred thermal transfer ink layers remaining on the substrate, and are discarded without being reused. Promoting the reuse of plastics and other materials is essential to reducing environmental impact and achieving the Sustainable Development Goals (SDGs).

[0003] Regarding thermal transfer ink ribbons, methods have also been proposed for collecting and recycling used thermal transfer ink ribbons. For example, there is a thermal transfer ink recovery device for thermal transfer ink ribbons (Patent Document 1), which has a heater downstream of the thermal transfer device that heats and melts the thermal transfer ink layer of the ink ribbon after thermal transfer, a scraping blade that is in contact with the thermal transfer ink ribbon to scrape off the melted thermal transfer ink, and a collection container to collect the scraped off thermal transfer ink; a thermal transfer ink recovery device for thermal transfer ink ribbons (Patent Document 2), which has a heating section that heats the thermal transfer ink ribbon, a pressure roller (pressure section) that pressurizes the thermal transfer ink ribbon heated by the heating section, a scraping section that scrapes off the thermal transfer ink adhering to the surface of the pressure roller, a recovery section that recovers the scraped off thermal transfer ink, and a discharge section that discharges the thermal transfer ink ribbon from which the thermal transfer ink has been squeezed out by the pressure roller; and a method for recycling thermal transfer ink ribbons (Patent Document 3), which is characterized by washing the thermal transfer ink ribbon with an ink dispersion type solvent, thereby peeling the thermal transfer ink layer from the substrate and dispersing it in the solvent, and recycling the substrate.

[0004] In Patent Documents 1 and 2, the thermal transfer ink layer is heated and melted before being scraped off from the substrate, which requires a large amount of energy, particularly when the melting point of the thermal transfer ink layer is high, and the scraped off thermal transfer ink may harden in the collection container, making it difficult to remove. Furthermore, in Patent Document 3, a solvent is used as the ink dispersion medium, which requires the solvent to be newly prepared and the solvent to be changed depending on the type of ink, which is undesirable from the perspectives of resource conservation and environmental protection. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Actual Publication Showa 62-11651 [Patent Document 2] Patent Publication No. 2004-284343 [Patent Document 3] Patent Publication No. 2001-164034 Summary of the Invention [Problem to be solved by the invention]

[0006] To provide a method for recycling a thermal transfer ink ribbon by recovering the thermal transfer ink layer of the thermal transfer ink ribbon efficiently and with good workability without providing a device for heating to a high temperature or using a new solvent. [Means for solving the problem]

[0007] The means for achieving the object of the present invention will be specifically described below.

[0008] The first invention is a device for separating and recovering thermal transfer ink from a thermal transfer ink ribbon that has a substrate and a thermal transfer ink layer on the substrate, and is characterized by having a cooling section that cools the thermal transfer ink ribbon to below 0°C and a folding section that folds the thermal transfer ink ribbon.

[0009] The second invention is a thermal transfer ink recovery device for a thermal transfer ink ribbon described in the first invention, characterized in that the folded portion has an edge with an angle of 90° or less, or in the case of a roll shape, the angle between the inlet direction and the outlet direction of the thermal transfer ink ribbon is 90° or less.

[0010] The third invention is a thermal transfer ink recovery device for a thermal transfer ink ribbon described in the first invention, characterized in that a scraping portion for scraping off the thermal transfer ink is provided at the folding portion in contact with the thermal transfer ink ribbon.

[0011] The fourth invention is a thermal transfer ink recovery device described in the first, second, and third inventions, characterized in that a heating section for heating the thermal transfer ink ribbon is provided before a cooling section for cooling the thermal transfer ink ribbon.

[0012] The fifth invention is a thermal transfer ink recovery device according to the first, second and third inventions, which is used to recover thermal transfer ink from a thermal transfer ink ribbon in which the substrate of the thermal transfer ink ribbon is a PET film, the thermal transfer ink layer is formed by laminating multiple inks in layers on the substrate, one or more layers of the thermal transfer ink layer that do not directly contact the substrate contain at least wax, and the total solid content forming the thermal transfer ink layer contains 30% or more wax.

[0013] The sixth invention is a thermal transfer ink recovery device described in the fifth invention, characterized in that a heating section for heating the thermal transfer ink ribbon to a temperature above the melting point of the wax is provided before the cooling section for cooling the thermal transfer ink ribbon.

[0014] The seventh invention is a thermal transfer ink recovery device according to the first, second and third inventions, which is used to recover thermal transfer ink from a thermal transfer ink ribbon in which the base material is a PET film, the thermal transfer ink layer is formed by laminating one or more inks in layers on the base material, and the total solid content forming the thermal transfer ink layer contains 30% or more of an elastomer with a glass transition temperature of 0°C or lower. [Effects of the Invention]

[0015] The thermal transfer ink recovery device of the present invention allows for the efficient and easy recovery of thermal transfer ink layers by recovering the thermal transfer ink layer of a thermal transfer ink ribbon in its solid state without the need for a device for heating to high temperatures or the use of additional solvents, thereby recycling the thermal transfer ink ribbon. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram showing one embodiment of a thermal transfer ink recovery device of the present invention. [Figure 2] 10 is a schematic diagram showing the angle formed between the approach direction and the delivery direction of the thermal transfer ink ribbon according to claim 2. FIG. [Figure 3] 10 is a schematic view showing one embodiment of a thermal transfer ink recovery device according to claim 3. FIG. [Figure 4] 10 is a schematic view showing one embodiment of a thermal transfer ink recovery device according to claim 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the thermal transfer ink recovery device of the present invention will be described in detail.

[0018] Fig. 1 is a schematic diagram showing one embodiment of a thermal transfer ink recovery device according to the present invention. This device separates and recovers thermal transfer ink from a thermal transfer ink ribbon comprising a substrate and a thermal transfer ink layer on the substrate. It includes a cooling section that cools the thermal transfer ink ribbon unwound from the unwinding section, and a folding section for folding back the thermal transfer ink ribbon immediately after the cooling section. A recovery container is provided below the folding section to recover thermal transfer ink that has fallen off the thermal transfer ink ribbon, and the thermal transfer ink ribbon after the thermal transfer ink has fallen off is wound up in the winding section. A drive control device can also be provided that can arbitrarily set the tension of the thermal transfer ink ribbon during transport.

[0019] The cooling unit must be able to cool the thermal transfer ink ribbon to a temperature of 0°C or below, preferably -10°C or below, and more preferably -20°C or below. The thermal transfer ink ribbon can be cooled by contacting a cooling / heating plate with the back side, ink side, or both sides of the thermal transfer ink ribbon, or by installing a housing with an inlet and outlet that can cool the inside. Although this is not very desirable from the perspective of energy conservation, the same effect can be achieved by installing the entire thermal transfer ink recovery device in an environment that can maintain the above low temperatures, instead of installing a cooling unit within the thermal transfer ink recovery device.

[0020] A folding section is provided immediately after the cooling section to fold the thermal transfer ink ribbon within a range that maintains the cooling effect. The thermal transfer ink in a thermal transfer ink ribbon tends to lose adhesion to the substrate at low temperatures. Therefore, the folding section is provided to apply stress to the thermal transfer ink ribbon immediately after cooling, causing the thermal transfer ink to fall off the substrate. The sharper the folding angle, the greater the effect of the thermal transfer ink falling off the substrate. Therefore, the folding section preferably has an edge with an angle of 90° or less, or, in the case of a roll, the angle between the entry direction and the exit direction of the thermal transfer ink ribbon (A in Figure 2) is preferably 90° or less. Furthermore, if the radius of the folding section is too large, the effect of the thermal transfer ink falling off the substrate is reduced. Therefore, the shape of the folding section, the edge radius in the case of an edge, or the roll radius in the case of a roll, is preferably 1.5 mm or less, more preferably 1.0 mm or less, and even more preferably 0.5 mm or less. Materials such as metal, glass, and plastic can be used without any particular restrictions.

[0021] As shown in Figure 3, the folded portion may be provided with a scraping portion in contact with the thermal transfer ink ribbon to scrape off the thermal transfer ink. By providing a scraping portion, it becomes possible to more effectively recover the thermal transfer ink, which tends to fall off the substrate, especially when the folded portion is in a roll shape.

[0022] A collection container is installed below the folded section to collect the thermal transfer ink that has fallen off the substrate. The thermal transfer ink to be collected is solid, so it can be easily removed and collected without adhering to the collection container and making it difficult to remove, as is the case when the thermal transfer ink is melted and collected.

[0023] The substrate, which has passed through the folded portion and from which the thermal transfer ink has fallen off, is wound up and collected at the winding portion.

[0024] The thermal transfer ink ribbon used in the thermal transfer ink recovery device of the present invention may be not only a used ink ribbon, but also an unused ink ribbon or a waste thermal transfer ink ribbon generated in the ink ribbon manufacturing process.

[0025] Among the thermal transfer ink ribbons, a hot-melt ink ribbon can be suitably used as the thermal transfer ink ribbon for use in the present invention. Typically, a heat-melt thermal transfer ink layer is provided on a substrate with a heat-resistant slipping layer, and the thermal transfer ink layer is a single layer or, if necessary, a laminate of multiple layers such as a release layer, a colored ink layer, and an adhesive layer. A PET film with a thickness of 2 to 12 μm is usually used as the substrate. The thermal transfer ink layer is a mixture of a thermoplastic resin, a binder such as wax, and a colorant such as a pigment or dye.

[0026] In particular, when the thermal transfer ink ribbon has a substrate of PET film, the thermal transfer ink layer is formed by laminating multiple inks on the substrate, and one or more layers of the thermal transfer ink layer that do not directly contact the substrate contain at least wax, and the wax content of the total solid content of the thermal transfer ink layer is 30% or more, preferably 50% or more, and more preferably 70% or more. Furthermore, when using a thermal transfer ink ribbon of this configuration, as shown in Figure 4, a heating section that can heat the thermal transfer ink ribbon to a temperature above the melting point of the wax is provided before the cooling section, and the thermal transfer ink layer is cooled after being heated. This allows for even more effective thermal transfer ink recovery. This is because the wax in the layer of the thermal transfer ink layer that does not directly contact the substrate melts, dissolving the wax into the layer that is in direct contact with the substrate, increasing the wax content in that layer, further reducing the adhesion between the substrate and the thermal transfer ink layer when cooled to below 0°C. As the wax, conventionally used waxes such as polyethylene wax, carnauba wax, paraffin wax, microcrystalline wax, montan wax, oxide wax, synthetic wax, etc. can be used, and two or more of these can also be mixed if necessary.

[0027] Furthermore, when the substrate of a thermal transfer ink ribbon is a PET film and the thermal transfer ink layer contains 30% or more, preferably 50% or more, and more preferably 70% or more of an elastomer with a glass transition temperature of 0°C or lower based on the total solid content of the thermal transfer ink layer, the thermal transfer ink recovery device of the present invention can more effectively recover the thermal transfer ink by lowering the temperature of the cooling section below the glass transition temperature of the elastomer. This is because the elastomer contained in the thermal transfer ink layer is rubbery and flexible at room temperature. However, when cooled below the glass transition temperature, it loses its rubbery properties and flexibility, making it unable to conform to the substrate at the folded portion and prone to falling off the substrate. Examples of elastomers that can be used include conventional elastomers such as ethylene-vinyl acetate copolymer (EVA), polyurethane, polyester, polyester urethane, styrene-butadiene-styrene block copolymer (SBS), styrene-butadiene rubber (SBR), and styrene-isoprene-styrene block copolymer (SIS). These can also be mixed in combination as needed. [Example]

[0028] The thermal transfer ink recovery device of the present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Hereinafter, when the amount of each material is expressed as "parts," it means "parts by weight" unless otherwise specified.

[0029] <Making thermal transfer ink ribbon> A thermal transfer ink ribbon was prepared by providing a thermal transfer ink layer of the following composition on one side of a 4.5 μm thick PET film having a heat-resistant lubricating layer on the other side.

[0030] (Thermal transfer ink ribbon 1) A coating liquid for the colored ink layer, consisting of 70 parts polyethylene wax (melting point 80°C), 15 parts ethylene-vinyl acetate copolymer (melting point 73°C), and 15 parts carbon black, was applied by gravure coating so that the coating thickness after drying would be 2 μm, and the resulting material was heated and dried to form a colored ink layer, producing thermal transfer ink ribbon 1.

[0031] (Thermal transfer ink ribbon 2) An adhesive layer coating liquid composed of 80 parts of carnauba wax (melting point 83°C) and 20 parts of terpene phenol resin (softening point 100°C) was applied onto the colored ink layer of the thermal transfer ink ribbon 1 using a gravure coating method so that the coating thickness after drying would be 1 μm, and the coating was heated and dried to form an adhesive layer, thereby producing thermal transfer ink ribbon 2.

[0032] (Thermal transfer ink ribbon 3) A release layer coating solution consisting of 70 parts polyethylene wax (melting point 80°C), 15 parts ethylene-vinyl acetate copolymer (melting point 73°C), and 15 parts terpene phenol resin (softening point 100°C) was applied by bar coating to a dry thickness of 0.5 μm and then heated and dried to form a release layer. A colored ink layer coating solution having the same composition as that of thermal transfer ink ribbon 1 was applied to the release layer by gravure coating to a dry thickness of 1.5 μm and then heated and dried to form a colored ink layer. An adhesive layer coating solution consisting of 30 parts carnauba wax (melting point 83°C), 20 parts ethylene-vinyl acetate copolymer (melting point 73°C), and 50 parts terpene phenol resin (softening point 100°C) was applied to the colored ink layer by gravure coating to a dry thickness of 1 μm and then heated and dried to form an adhesive layer, producing thermal transfer ink ribbon 3.

[0033] (Thermal transfer ink ribbon 4) A colored ink layer coating solution consisting of 10 parts polyethylene wax (melting point 100°C), 20 parts ethylene-vinyl acetate copolymer (melting point 73°C), 50 parts petroleum resin (softening point 100°C), and 20 parts carbon black was applied by gravure coating to a dry thickness of 1.5 μm and then heated and dried to form a colored ink layer. A coating solution for an adhesive layer consisting of 80 parts polyethylene wax (melting point 100°C) and 20 parts polyester resin (Mn 15000, Tg 67°C) was applied by gravure coating to a dry thickness of 0.6 μm and then heated and dried to form an adhesive layer, producing thermal transfer ink ribbon 4.

[0034] (Thermal transfer ink ribbon 5) A colored ink layer coating solution consisting of 40 parts (30% of the total solids in the ink layer) of ethylene-vinyl acetate copolymer (melting point 73°C, glass transition temperature -28°C), 40 parts of petroleum resin (softening point 100°C), and 20 parts of carbon black was applied by gravure coating to a dry thickness of 1.5 μm and then heated and dried to form a colored ink layer. A coating solution consisting of 100 parts of polyester resin (Mn 15000, Tg 67°C) was applied by gravure coating to a dry thickness of 0.5 μm and then heated and dried to form an adhesive layer, producing thermal transfer ink ribbon 5.

[0035] <Used thermal transfer ink ribbon> The thermal transfer ink ribbons 1 to 5 (100 mm wide x 100 m long) were prepared, and a Zebra 110Xi4 (300 dpi) was used to print a predetermined printing pattern consisting of characters, barcodes, etc. on a Lintec FR1415 (PET film), obtaining used thermal transfer ink ribbons 1 to 5.

[0036] Example 1 A thermal transfer ink recovery device with the configuration shown in Figure 1 was prepared, the temperature of the cooling section was set to 0°C, a metal plate with an edge at an angle of 90° and an edge radius of 1.0 mm was used at the folding section, and the edge of the metal plate was placed 30 mm from the outlet of the cooling section so that it was perpendicular to the running direction of the thermal transfer ink ribbon as shown in Figure 1, and the used thermal transfer ink ribbon 1 was run along the edge of the metal plate to conduct an ink recovery test.

[0037] Example 2 An ink recovery test was carried out in the same manner as in Example 1, except that the temperature of the cooling section of the thermal transfer ink recovery device was changed to -10°C.

[0038] Example 3 An ink recovery test was carried out in the same manner as in Example 1, except that the temperature of the cooling section of the thermal transfer ink recovery device was changed to -20°C.

[0039] Example 4 An ink recovery test was conducted in the same manner as in Example 1, except that used thermal transfer ink ribbon 1 was replaced with used thermal transfer ink ribbon 2 and the folded portion was replaced with a metal plate having an edge with an angle of 90° and an edge radius of 0.5 mm.

[0040] Example 5 An ink recovery test was carried out in the same manner as in Example 4, except that a heating section as shown in Figure 4 was installed before the cooling section of the thermal transfer ink recovery device, and the temperature of the heating section was set to 90°C to heat the used thermal transfer ink ribbon 2.

[0041] Example 6 A thermal transfer ink recovery device with the configuration shown in Figure 3 was prepared, the temperature of the cooling section was set to 0°C, a metal roll with a roll radius of 1.5 mm was used in the turning-back section, the distance from the outlet of the cooling section until the thermal transfer ink ribbon first came into contact with the metal roll was 30 mm, the angle between the inlet and outlet directions of the thermal transfer ink ribbon was 70°, and the running direction of the thermal transfer ink ribbon was perpendicular to the axial direction of the roll. Furthermore, a steel scraping blade was installed in the turning-back section in contact with the thermal transfer ink ribbon as a scraping section for scraping off the thermal transfer ink, and an ink recovery test was conducted using 3 used thermal transfer ink ribbons.

[0042] Example 7 An ink recovery test was carried out in the same manner as in Example 6, except that a heating section as shown in Figure 4 was installed before the cooling section of the thermal transfer ink recovery device, and the temperature of the heating section was set to 90°C to heat the used thermal transfer ink ribbon 3.

[0043] Example 8 An ink recovery test was carried out in the same manner as in Example 1, except that the used thermal transfer ink ribbon 1 was replaced with the used thermal transfer ink ribbon 4, a heating section as shown in Figure 4 was provided before the cooling section of the thermal transfer ink recovery device, and the temperature of the heating section was set to 110°C to heat the used thermal transfer ink ribbon 4.

[0044] Example 9 An ink recovery test was carried out in the same manner as in Example 1, except that the used thermal transfer ink ribbon 1 was replaced with the used thermal transfer ink ribbon 5 and the temperature of the cooling section of the thermal transfer ink recovery device was changed to -40°C.

[0045] (Comparative Example 1) An ink recovery test was carried out in the same manner as in Example 1, except that the temperature of the cooling section of the thermal transfer ink recovery device was changed to 10°C.

[0046] (Comparative Example 2) An ink recovery test was carried out in the same manner as in Example 4, except that the temperature of the cooling section of the thermal transfer ink recovery device was changed to 10°C.

[0047] (Comparative Example 3) An ink recovery test was carried out in the same manner as in Example 7, except that the temperature of the cooling section of the thermal transfer ink recovery device was changed to 10°C.

[0048] <Ink recovery rate evaluation> From the results of the ink recovery tests of Examples 1 to 9 and Comparative Examples 1 to 3, the ink recovery rate was calculated using the following formula 1. The amount of ink remaining before ink recovery was calculated by multiplying the applied amount of the thermal transfer ink ribbon by the area (width 100 mm x winding length 100 m = 10 m 2 ) calculated from the total ink amount {total ink application amount (g / m 2 )×10(m 2 )} and the difference between the amount of ink used for printing {weight of ink ribbon before printing - weight of ink ribbon after printing}. The results of evaluation according to the following evaluation criteria are shown in Table 1. (Formula 1) Ink recovery rate (%) = {amount of ink recovered ÷ amount of ink remaining before ink recovery} x 100 (Evaluation criteria) ◎: Ink recovery rate is 70% or more ○: Ink recovery rate is 30% or more but less than 70% ×: Ink recovery rate is less than 30%

[0049] [Table 1] [Explanation of symbols]

[0050] 10: Thermal transfer ink ribbon before ink collection 20: Thermal transfer ink 30: Cooling section 40: Folded section 50: Ink collection container 60: Thermal transfer ink ribbon after ink recovery 70: scraping section 80: Heating part A: The angle between the inlet and outlet directions of the thermal transfer ink ribbon

Claims

1. A device for separating and recovering thermal transfer ink from a thermal transfer ink ribbon having a substrate and a thermal transfer ink layer on the substrate, characterized in that the device is provided with a cooling section for cooling the thermal transfer ink ribbon to below 0°C and a folding section for folding back the thermal transfer ink ribbon.

2. A thermal transfer ink recovery device for a thermal transfer ink ribbon described in the first invention, characterized in that the folded portion has an edge with an angle of less than 90 degrees, or in the case of a roll shape, the angle between the inlet direction and the outlet direction of the thermal transfer ink ribbon is less than 90 degrees.

3. 2. The thermal transfer ink recovery device for a thermal transfer ink ribbon according to claim 1, wherein a scraping portion for scraping off the thermal transfer ink is provided at the folded portion in contact with the thermal transfer ink ribbon.

4. 4. The thermal transfer ink recovery device according to claim 1, wherein a heating section for heating the thermal transfer ink ribbon is provided before a cooling section for cooling the thermal transfer ink ribbon.

5. A thermal transfer ink recovery device as described in claims 1, 2, and 3, which is used to recover thermal transfer ink from a thermal transfer ink ribbon whose base material is a PET film, whose thermal transfer ink layer is formed by laminating multiple inks in layers on the base material, whose thermal transfer ink layer contains at least wax in one or multiple layers that do not directly contact the base material, and whose thermal transfer ink layer contains 30% or more of wax in the total solid content that forms the thermal transfer ink layer.

6. 6. The thermal transfer ink recovery device according to claim 5, further comprising a heating section for heating the thermal transfer ink ribbon to a temperature exceeding the melting point of the wax, before the cooling section for cooling the thermal transfer ink ribbon.

7. A thermal transfer ink recovery device as described in claims 1, 2, and 3, which is used to recover thermal transfer ink from a thermal transfer ink ribbon whose base material is a PET film, whose thermal transfer ink layer is formed by laminating one or more inks in layers on the base material, and whose total solid content forming the thermal transfer ink layer contains 30% or more of an elastomer having a glass transition temperature of 0°C or less.

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