Thermal transfer recording medium and printing device

Abstract

To provide a thermal transfer recording medium that can record characters of at least two colors and prevent the fringes of a different color from occurring when transferring one color.SOLUTION: A thermal transfer recording medium 47 includes: a base material layer 48 having a front surface 53 and a rear surface 54; and a welding layer 70, a first thermal transfer layer 50, an intermediate layer 51, and a second thermal transfer layer 52 laminated in direct contact with each other in this order on the front surface 53 of the base material layer 48. The combined thickness before thermal transfer, of all layers that break to separate from the base material layer 48 side in a first state where the thermal transfer recording medium 47 is heated to a level equal to or higher than a first temperature and equal to or lower than a second temperature and then cooled to a level equal to or lower than a third temperature (for example, during low-temperature heating) is smaller than the thickness of the first thermal transfer layer 50.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present disclosure relates to a thermal transfer recording medium capable of recording characters of different colors, and a printing device for transferring the thermal transfer recording medium onto a print-receiving medium. [Background technology]

[0002] For example, Patent Documents 1 and 2 disclose thermal transfer recording media capable of recording characters of different colors (for example, two colors, black and red). This type of thermal transfer recording medium is set in a dedicated printing device. By adjusting the amount of energy applied to the thermal head of the printing device, characters of different colors can be transferred onto the print-receiving medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-094843 [Patent Document 2] Japanese Patent Application Publication No. 62-227788 [Patent Document 3] Japanese Patent Application Publication No. 63-214481 Summary of the Invention [Problem to be solved by the invention]

[0004] One embodiment of the present disclosure provides a thermal transfer recording medium capable of recording characters in two colors, which can suppress the occurrence of fringes of one color that occur when the other color is transferred. [Means for solving the problem]

[0005] A thermal transfer recording medium according to one embodiment of the present disclosure comprises a substrate layer, a first ink layer containing a first ink, and a second ink layer containing a second ink, laminated in this order, and at least a portion of the first ink layer and the second ink layer being thermally transferred to a print-receiving medium; when the thermal transfer recording medium is in a first state in which it is heated to a temperature above a first temperature and below a second temperature and then cooled to a third temperature or below, and an external force is applied to the substrate layer and the second ink layer in a direction moving them away from each other, the thermal transfer recording medium breaks between the first ink layer and the second ink layer or within the second ink layer; when the thermal transfer recording medium is in a second state in which it is heated to a temperature above the second temperature and then cooled to a third temperature or below, and an external force is applied, the thermal transfer recording medium breaks between the first ink layer and the substrate layer or within the first ink layer; and the sum of the thicknesses before thermal transfer of all layers that break and move away from the substrate layer in the first state is thinner than the first ink layer. [Effects of the Invention]

[0006] According to the thermal transfer recording medium according to an embodiment of the present disclosure, it is possible to suppress the occurrence of fringes of one color that occur when one of two color characters is transferred. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram schematically illustrating the structure of a printing device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing the electrical configuration of the printing device. [Figure 3] FIG. 3 is a schematic diagram illustrating the heating process and the cooling process of the printing device. [Figure 4] 4A and 4B are schematic diagrams illustrating the cooling step and the transfer step of the printing device. [Figure 5] 5A and 5B are diagrams showing examples of patterns printed by the printing device. [Figure 6] FIG. 6 is a diagram showing a fringe pattern that occurs during thermal transfer. [Figure 7]FIG. 7 is a diagram showing the circuit pattern of the heating elements of the thermal head of FIG. [Figure 8] FIG. 8 is a diagram for explaining the temperature distribution of the heating element in FIG. [Figure 9] FIG. 9 is a diagram for explaining how heat is transferred from the thermal head to the thermal transfer recording medium. [Figure 10] FIG. 10 is a diagram showing the relationship between the heating temperature and adhesive strength at the boundaries of the layers of the thermal transfer recording medium. [Figure 11] FIG. 11 is a diagram for explaining the principle of the generation of the fringes. [Figure 12] FIG. 12 is a diagram for explaining the solution to the fringe problem. [Figure 13] FIG. 13 is a schematic cross-sectional view showing the layer structure of a thermal transfer recording medium according to an embodiment of the present disclosure. [Figure 14] FIG. 14 is a diagram showing the relationship between the elapsed time and the temperature reached by the thermal transfer recording medium in the heating step and the cooling step. [Figure 15] FIG. 15 is a diagram showing the state of peeling of the thermal transfer recording medium. [Figure 16] FIG. 16 is a diagram showing the state of peeling of the thermal transfer recording medium. [Figure 17] FIG. 17 is a diagram showing the state of peeling of the thermal transfer recording medium. [Figure 18] FIG. 18 is a diagram showing the state of peeling of the thermal transfer recording medium. [Figure 19] FIG. 19 is a diagram showing the state of peeling of the thermal transfer recording medium. DETAILED DESCRIPTION OF THE INVENTION

[0008] Next, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0009] [Overall configuration of printing device 1] FIG. 1 is a diagram schematically illustrating the structure of a printing device 1 according to an embodiment of the present disclosure.

[0010] 1, the printing device 1 is a thermal printer of the thermal transfer type that thermally transfers ink from an ink ribbon 3 as characters onto a printer tape 2, which is an example of a print medium. The printer tape 2 may include, for example, a strip-shaped film tape including a base material onto which ink is directly transferred, or a paper label tape in which many paper labels are arranged on a strip-shaped base film.

[0011] The characters recorded on the printer tape 2 may include, for example, typical characters, symbols such as barcodes and QR codes (registered trademarks), numbers, figures, patterns, etc. The printing device 1 according to this embodiment can record characters of different colors (for example, two colors, black and red) on the printer tape 2.

[0012] The printing device 1 mainly includes a housing 4, a tape cassette 5 housed inside the housing 4, a thermal head 6, a platen roller 7, and a control board 8.

[0013] The housing 4 may be a box-shaped member made of, for example, a plastic case. An outlet 9 is formed on the outer wall of the housing 4 for removing the printer tape 2 after printing. A cutter (not shown) may be provided near the outlet 9. By cutting with the cutter, the printer tape 2 can be separated into labels of a size appropriate for each unit of use and removed.

[0014] The tape cassette 5 may be a cartridge that is detachable from the housing 4. The tape cassette 5 may house, in order from upstream to downstream in the tape feed direction D1 (the direction from right to left in FIG. 1 ), a printer tape roll 10 (which may alternatively be a label tape roll), a supply roller 11, an ink ribbon roll 12, an ink ribbon peeling member 13, and an ink ribbon take-up roll 14. In this embodiment, the printer tape roll 10 and the ink ribbon roll 12 are of a type that are used while housed in the tape cassette 5, but they may also be of a type that is used by being directly attached to the printing device 1, for example.

[0015] Printer tape roll 10 is made by winding printer tape 2 into a cylindrical shape and is rotatably held in, for example, tape cassette 5. Tape drive shaft 16 provided in housing 4 is inserted into supply roller 11. Rotational force R1 generated by driving tape drive shaft 16 is transmitted to supply roller 11, causing supply roller 11 to rotate.

[0016] The ink ribbon roll 12 is made by winding the ink ribbon 3 into a cylindrical shape, and is rotatably held in, for example, a tape cassette 5. A ribbon drive shaft 18 provided in the housing 4 is inserted into the ink ribbon take-up roll 14. A rotational force R2 generated by driving the ribbon drive shaft 18 is transmitted to the ink ribbon take-up roll 14, causing the ink ribbon take-up roll 14 to rotate.

[0017] The ink ribbon separating member 13 may be a guide member that changes the feed direction D2 of the ink ribbon 3. The ink ribbon separating member 13 may have a shape that can come into contact with the ink ribbon 3 while it is being transported, such as a roller or blade shape. A portion of the ink ribbon 3 is thermocompressed to the printer tape 2 by the thermal head 6, and is transported together with the printer tape 2 toward the outlet 9. The ink ribbon separating member 13 comes into contact with the ink ribbon 3 while it is being transported, and changes the feed direction D2 of the ink ribbon 3 at a steep angle relative to the feed direction D1 of the printer tape 2. This causes the printer tape 2 and the ink ribbon 3 to be separated, and the ink ribbon 3 is separated from the printer tape 2.

[0018] The thermal head 6 is disposed between the printer tape roll 10, the ink ribbon roll 12, and the ink ribbon peeling member 13 in the feed direction D1 of the printer tape 2. The thermal head 6 includes a substrate 19 and a heating element 20 (e.g., a heating resistor) formed on the substrate 19. Joule heat generated by energizing the heating element 20 is used for thermal transfer of ink from the ink ribbon 3.

[0019] For example, a platen drive shaft 21 provided in the housing 4 is inserted into the platen roller 7. A rotational force R3 generated by driving the platen drive shaft 21 is transmitted to the platen roller 7, causing the platen roller 7 to rotate. The control board 8 is an electronic device that performs electrical control of the printing device 1, and is installed inside the housing 4.

[0020] [Electrical configuration of printing device 1] FIG. 2 is a block diagram showing the electrical configuration of the printing device 1. As shown in FIG.

[0021] 2, a control circuit 22 is provided on the control board 8 of the printing device 1. The control circuit 22 may include a CPU 23, a ROM 24, a memory 25, a RAM 26, and an input / output I / F 27 (interface), which are electrically connected via, for example, a data bus (not shown).

[0022] The ROM 24 stores various programs for driving the printing device 1 (for example, control programs for executing the steps shown in FIG. 3 and FIGS. 4A and 4B). The CPU 23 executes signal processing in accordance with the programs stored in the ROM 24 while utilizing the temporary storage function of the RAM 26, and controls the printing device 1 as a whole. The memory 25 may be configured, for example, as a part of the storage area of ​​the ROM 24. The memory 25 may also store in advance a table for displaying the remaining amount (amount consumed) of the ink ribbon 3 on a display unit (not shown) of the housing 4.

[0023] A first drive circuit 28 and a second drive circuit 29 are electrically connected to the input / output I / F 27. The first drive circuit 28 controls the energization of the heating elements 20 of the thermal head 6. The second drive circuit 29 controls the drive to output drive pulses to a drive motor 30 that drives the supply roller 11, the ink ribbon take-up roll 14, and the platen roller 7 to rotate.

[0024] [Printing process flow by printing device 1] FIG. 3 is a schematic diagram illustrating the heating process and cooling process of the printing device 1. FIGS. 4 and 4B are schematic diagrams illustrating the cooling process and transfer process of the printing device 1. FIG. 4B is an enlarged view of a main part of the transfer pattern when viewed from the direction of arrow 4B in FIG. 4A. FIGS. 5A and 5B are diagrams showing an example of a print pattern 44 printed by the printing device 1. The printing process by the printing device 1 will be specifically described with reference to FIGS. 1 and 3 to 5A and 5B.

[0025] To print characters on the printer tape 2, the printer tape 2 is fed from the printer tape roll 10 by the rotational drive of the supply roller 11, and the ink ribbon 3 is fed from the ink ribbon roll 12 by the rotational drive of the ink ribbon take-up roll 14. As a result, the printer tape 2 and the ink ribbon 3 are transported downstream while overlapping each other, as shown in Figures 1 and 3. The surface of the printer tape 2 facing the ink ribbon 3 is the printing surface 31 (front surface), and the opposite surface is the back surface 32. The surface of the ink ribbon 3 facing the printer tape 2 is the adhesive surface 33 (front surface), and the opposite surface is the back surface 34.

[0026] 3, the ink ribbon 3 includes a base layer 35, a first ink layer 36 as an example of a first thermal transfer layer, and a second ink layer 37 as an example of a second thermal transfer layer. The first ink layer 36 and the second ink layer 37 are laminated in this order on a front surface 38 as an example of a first surface of the base layer 35. The surface of the base layer 35 opposite the front surface 38 is a back surface 39 (back surface 34 of the ink ribbon 3). The first ink layer 36 and the second ink layer 37 contain colorants of different colors. For example, the first ink layer 36 may contain a black colorant as an example of a first ink, and the second ink layer 37 may contain a red colorant as an example of a second ink.

[0027] The ink ribbon 3 is transported toward the thermal head 6 with the second ink layer 37 and the printer tape 2 in contact with each other. The thermal head 6 performs a heating process as shown in Figure 3. Specifically, when the heating element 20 is energized and heated, it is pressed against the ink ribbon 3, and the heat is transferred to the first ink layer 36 and the second ink layer 37 via the base layer 35. The laminate of the ink ribbon 3 and the printer tape 2 is sandwiched between the thermal head 6 and the platen roller 7, and is transported downstream while being heated by the thermal head 6.

[0028] The heating element 20 may be controlled to the same temperature throughout, or may be controlled to partially different temperatures. For example, as shown in FIG. 3 , a first portion 40 of the heating element 20 may be controlled to a first heating temperature, and a second portion 41 of the heating element 20 may be controlled to a second heating temperature different from the first heating temperature. As a result, the ink ribbon 3 may include a first portion 42 heated to the first heating temperature and a second portion 43 heated to the second heating temperature. In the first portion 42 and the second portion 43 of the ink ribbon 3, at least part or all of the first ink layer 36 and the second ink layer 37 melt or soften and adhere to the printer tape 2.

[0029] 3 and 4A and 4B, a cooling process is carried out in the section between the thermal head 6 and the ink ribbon peeling member 13. Specifically, the ink ribbon 3, which has been thermocompressed to the printer tape 2 in the heating process, is naturally cooled in the section from the thermal head 6 to the ink ribbon peeling member 13, and its temperature drops toward the ambient temperature in which the printing device 1 is used.

[0030] 4A and 4B, the ink ribbon peeling member 13 selectively changes only the feed direction D2 of the ink ribbon 3, thereby applying an external force F1 to the base layer 35 and the second ink layer 37 in directions that move them away from each other. This separates the printer tape 2 and the ink ribbon 3, and the ink ribbon 3 is taken up onto the ink ribbon take-up roll 14. At this time, the first portion 42 and the second portion 43 of the ink ribbon 3, which have been heated by the thermal head 6, selectively remain on the printer tape 2, thereby performing the transfer process. For example, in the first portion 42, peeling may occur between the base layer 35 and the laminate including the first ink layer 36 and the second ink layer 37, resulting in the transfer of the laminate. Meanwhile, in the second portion 43, peeling may occur between the first ink layer 36 and the second ink layer 37, resulting in the selective transfer of the second ink layer 37.

[0031] As a result, printed patterns 44 of different colors (for example, two colors, black and red) are formed on the printer tape 2. The printed pattern 44 may have different colors for each individual character, as shown in FIG. 5A, for example. In FIG. 5A, when viewed from the printed surface 31 side of the printer tape 2, a red pattern 45 based on the second ink layer 37 may be visible on the outermost surfaces of the alphabet letters "A" and "C," and a black pattern 46 based on the first ink layer 36 may be visible on the outermost surface of "B." On the other hand, as shown in FIG. 5B, the printed pattern 44 may have both a red pattern 45 and a black pattern 46 visible for each part of each character.

[0032] After the ink ribbon 3 is transferred, the printer tape 2 on which the characters are recorded is removed from the outlet 9 of the printer 1. Through the above steps, the printed printer tape 2 can be obtained.

[0033] [Example of issues with two-color printing] In a thermal transfer thermal printer (printing device 1), the ink ribbon 3 is heated by the thermal head 6 according to the pattern of recording information, and then the ink ribbon 3 is peeled off from the printer tape 2. As a result, the ink layers 36, 37 are selectively melted or softened according to the heating pattern, peeled off from the base layer 35, and transferred to the printing surface 31 of the printer tape 2, recording characters on the printing surface 31. Two-color thermal transfer printing such as that described above is also disclosed in the aforementioned Patent Documents 1 and 2, but has the following problems.

[0034] For example, FIG. 6 shows a print pattern 44 on an ink ribbon in which red is transferred when heated at a low temperature and black is transferred when heated at a high temperature. Fringes may occur when only one of two color patterns is selectively transferred. For example, referring to FIG. 6, in black patterns 46 arranged in a polka-dot pattern with spaces between them, red pattern 45 may be selectively transferred as fringes 80 around the periphery of each pattern. This type of fringe 80 is thought to be caused by temperature distribution within the ink ribbon 3, and for example, the temperature required to transfer the black pattern 46 is not reached at the periphery of each pattern. The temperature distribution of the ink ribbon 3 is due to the temperature distribution of the heating element 20 of the thermal head 6. The principle behind the occurrence of fringes 80 will be explained in detail below with reference to FIGS. 7 to 11.

[0035] Fig. 7 is a diagram showing the circuit pattern of the heating element 20 of the thermal head 6 in Fig. 3. Fig. 8 is a diagram for explaining the temperature distribution of the heating element 20 in Fig. 7. For clarity, the heating element 20 is hatched in Fig. 7 and Fig. 8.

[0036] 7 and 8, the detailed structure of the thermal head 6 and the temperature distribution of the heating elements 20 will be described. First, referring to FIG. 7, in the thermal head 6, a plurality of heating elements 20 are regularly arranged at a predetermined pitch P1. The plurality of heating elements 20 are arranged, for example, in a vertical row perpendicular to the tape feed direction D1. Alternatively, the plurality of heating elements 20 may be arranged in rows in the vertical and horizontal directions.

[0037] In this embodiment, each heating element 20 is rectangular. The length L2 of each heating element 20 in the main scanning direction D3 may be, for example, 15 μm or more and 300 μm or less. The length L3 of each heating element 20 in the sub-scanning direction D4 may be longer than the length L2 in the main scanning direction D3. The sub-scanning direction D4 may be a direction perpendicular to the main scanning direction D3 and may also be the feed direction D1 of the printer tape 2. The predetermined pitch P1 is, for example, the distance from the center to the center of two adjacent heating elements 20. The predetermined pitch P1 may be, for example, 84.7 μm (300 dpi).

[0038] One terminal of each of the plurality of heating elements 20 may be connected to a common electrode 81 (for example, GND potential) common to all of the heating elements 20, and the other terminal may be connected to an electrically independent individual electrode 82. The first drive circuit 28 controls the temperature of each heating element 20 by adjusting the power supplied to each individual electrode 82 and the duration of current flow.

[0039] 8, the temperature distribution diagram below the heating element 20 shows the temperature distribution in the direction along the sub-scanning direction D4 of the heating element 20, and the temperature distribution diagram to the right of the heating element 20 shows the temperature distribution in the direction along the main scanning direction D3 of the heating element 20. When power (energy) is supplied to each heating element 20, the electrical energy is converted into thermal energy, and each heating element 20 generates heat. The temperature rise value of the heating element 20 due to heat generation can be calculated, for example, by the following equation (1).

[0040] T1=Q / C+T0 (1) In formula (1), T1 = temperature rise value, T0 = ambient temperature, Q = applied energy, and C = heat capacity of the heating element 20 (which depends on the shapes and materials of the thermal head 6 and heating element 20).

[0041] When applied energy Q is applied to the entire hatched portion of heating element 20, the heating temperature T1 value of the heating element will follow equation (1) and macroscopically attempt to form a temperature distribution shape as shown by dashed line 83. However, because heat has the tendency to move from high temperatures to low temperatures, heat escapes to the periphery of heating element 20 where applied energy Q is not applied, that is, toward the low ambient temperature T0, and so the microscopic temperature distribution will have a mountain-shaped shape, as shown by solid line 84, where the temperature is higher near the center and lower from the center to the periphery. Simply put, this is because heat escapes less easily from the center of heating element 20, while it escapes more easily from the periphery.

[0042] FIG. 9 is a diagram for explaining how heat is transferred from the thermal head 6 to the ink ribbon 3. As shown in FIG.

[0043] 9, heat from each heating element 20 in FIG. 8 is transferred from the base layer 35 to the first ink layer 36 and the second ink layer 37, in that order, into the interior of the ink ribbon 3. In FIG. 9, the manner in which heat is transferred from the heating element 20 to the interior of the ink ribbon 3 is shown by semi-elliptical temperature curves 85A to 85F. The temperature curves 85A to 85F are, in order from closest to the heating element 20, a first temperature curve 85A, a second temperature curve 85B, a third temperature curve 85C, a fourth temperature curve 85D, a fifth temperature curve 85E, and a sixth temperature curve 85F. The regions enclosed by the temperature curves 85A to 85F, respectively, are a first temperature region 86A, a second temperature region 86B, a third temperature region 86C, a fourth temperature region 86D, a fifth temperature region 86E, and a sixth temperature region 86F. During heating by the heating element 20, the temperatures that the temperature regions 86A to 86F reach have the following relationship: 86A>86B>86C>86D>86E>86F.

[0044] Therefore, when heated, there is a magnitude relationship in the temperature that is reached in the thickness direction of the ink ribbon 3. For example, the temperature that is reached at the first boundary portion 87 between the base layer 35 and the first ink layer 36, Tb (T base ), the temperature reached at the second boundary portion 88 between the first ink layer 36 and the second ink layer 37 Th(T high), and the temperature Tl (T low ), there is a magnitude relationship of Tb>Th>Tl. For clarity, in Figure 9, the portions directly below the heating elements 20 at the boundaries between the layers of the ink ribbon 3 are conceptually shown as a first rectangular boundary 87, a second rectangular boundary 88, and a third rectangular boundary 89.

[0045] Furthermore, the temperatures Tb, Th, and Tl are not uniform in the in-plane direction (the direction perpendicular to the thickness direction) of the ink ribbon 3, but rather have a magnitude relationship (temperature distribution). For example, in the second boundary 88 (first ink layer 36-second ink layer 37), the center is in the second temperature region 86B, while the peripheral region is in the third temperature region 86C, which is lower than the center. This in-plane temperature distribution of each boundary 87-89 is related to the occurrence of fringes 80.

[0046] FIG. 10 is a diagram showing the relationship between the heating temperature and the peel strength (adhesion strength) at the boundaries of the layers of the ink ribbon 3. In FIG.

[0047] Before explaining the relationship between the in-plane temperature distribution of each boundary 87-89 and the occurrence of fringe 80, we will explain the relationship between the temperatures Tb, Th, and Tl reached at the boundary 87-89 of each layer of the ink ribbon 3 and the peel strength (adhesion strength) of the boundary 87-89, with reference to Figure 10.

[0048] 10, the horizontal axis of Fig. 10 represents the temperature reached at the boundaries 87-89 of each layer of the ink ribbon 3, and the vertical axis of Fig. 10 represents the force (peeling force) required to peel the boundaries 87-89 of each layer of the ink ribbon 3. A solid line 90 in Fig. 10 represents the relationship between the peeling force and the temperature Th reached at the second boundary 88 (first ink layer 36-second ink layer 37), a dashed-dotted line 91 in Fig. 10 represents the relationship between the peeling force and the temperature Tl reached at the third boundary 89 (second ink layer 37-printer tape 2), and a dashed-two-dotted line 92 in Fig. 10 represents the relationship between the peeling force and the temperature Tb reached at the first boundary 87 (base layer 35-first ink layer 36).

[0049] As shown in Fig. 10, the magnitude relationship of the peel force at each boundary 87-89 is not constant, but changes according to the change in the temperatures Tb, Th, and Tl reached at the boundaries 87-89. For example, the horizontal axis in Fig. 10 may be divided into three main sections according to the magnitude of the temperatures Tb, Th, and Tl reached at the boundaries 87-89. The three sections include a first section 93, a second section 94, and a third section 95.

[0050] The first section 93 is the section in which the range of temperatures Tb, Th, and Tl reached by the boundaries 87 to 89 is the lowest. The magnitude relationship of the peel force at each boundary 87 to 89 in the first section 93 is third boundary 89 < second boundary 88 < first boundary 87. Since the peel force at the third boundary 89 is almost 0 (zero), the ink ribbon 3 is not adhered to the printer tape 2. In other words, the first section 93 may be in the initial state (state before thermal transfer) before energy is applied by the thermal head 6.

[0051] In the second section 94, the range of temperatures Tb, Th, and Tl reached at the boundaries 87-89 is between the first section 93 and the third section 95. The magnitude relationship of the peel force at the boundaries 87-89 in the second section 94 is second boundary 88<first boundary 87<third boundary 89, or second boundary 88<third boundary 89<first boundary 87. Therefore, the second ink layer 37 is adhered to the printer tape 2 via the third boundary 89, and the adhesion between the base layer 35 and the first ink layer 36 is sufficiently maintained via the first boundary 87. Meanwhile, the adhesive force between the first ink layer 36 and the second ink layer 37 via the second boundary 88 is the weakest. Therefore, when an external force F1 (see FIGS. 4A and 4B) is applied to the ink ribbon 3 in the second section 94, peeling occurs at the second boundary 88, where the adhesive force is weakest. As a result, so-called reverse transfer occurs, in which the first ink layer 36 remains on the base layer 35 side, while only the second ink layer 37 is selectively thermally transferred onto the printer tape 2. Therefore, the characters recorded on the printer tape 2 will have the color of the second ink layer 37, for example, red.

[0052] The third section 95 is the section in which the range of temperatures Tb, Th, and Tl reached by the boundaries 87-89 is the highest. The magnitude relationship of the peeling force at the boundaries 87-89 in the third section 95 is first boundary 87<third boundary 89<second boundary 88, or first boundary 87<second boundary 88<third boundary 89. Therefore, the second ink layer 37 is adhered to the printer tape 2 via the third boundary 89, and sufficient adhesion is maintained between the first ink layer 36 and the second ink layer 37 via the second boundary 88. Meanwhile, the adhesive force between the base layer 35 and the first ink layer 36 via the first boundary 87 is the weakest. Therefore, when an external force F1 (see FIGS. 4A and 4B) is applied to the ink ribbon 3 in the third section 95, peeling occurs at the first boundary 87, where the adhesive force is weakest. As a result, the entire ink ribbon 3, i.e., the first ink layer 36 and the second ink layer 37, are thermally transferred integrally onto the printer tape 2. As a result, the characters recorded on the printer tape 2 will have the color of the first ink layer 36, which is the outermost layer after transfer, such as black.

[0053] As described above, when an external force F1 is applied to the ink ribbon 3, which of the three boundaries 87-89 becomes the peeling position is related to the temperature reached by the boundaries 87-89. For example, during low-temperature heating when low energy is applied to the heating element 20 (second section 94), the peeling position is between the first ink layer 36 and the second ink layer 37, and the thermally transferred color is red. On the other hand, during high-temperature heating when high energy is applied to the heating element 20 (third section 95), the peeling position is between the base layer 35 and the first ink layer 36, and the thermally transferred color is black.

[0054] However, accurate transfer of two-color characters without the occurrence of fringe 80 is only possible if the temperatures Th and Tl reached at the second boundary 88 and the third boundary 89 are uniform throughout the entire in-plane direction of the boundary and meet the temperature conditions required for transfer. As shown in Figure 9, a temperature distribution normally occurs in the in-plane direction of the ink ribbon 3, and this is the cause of the occurrence of fringe 80.

[0055] Figure 11 is a diagram for explaining the principle behind the occurrence of fringes 80. Figure 12 is a diagram for explaining a solution to the fringes 80. In Figure 11, the thickness direction of the ink ribbon 3 is defined as direction D5, and the in-plane direction of the ink ribbon 3 perpendicular to the thickness direction D5 is defined as direction D6.

[0056] 11, the solid line in a mountain shape indicates a first temperature distribution curve 96 of the temperature Th reached at the outermost surface of the ink ribbon 3 that remains on the base layer 35 without being transferred when the second ink layer 37 is transferred, with the temperature highest at the top and decreasing toward the bottom. The dashed-dotted line in a mountain shape indicates a second temperature distribution curve 97 of the temperature Tl reached at the outermost surface of the ink ribbon 3 (i.e., the third boundary portion 89), with the temperature highest at the top and decreasing toward the bottom. The two straight lines that intersect the first temperature distribution curve 96 and the second temperature distribution curve 97, from top to bottom, respectively, indicate a high-temperature-side boundary condition 98 (corresponding to Th-tar in FIG. 10) required for transferring black and a low-temperature-side boundary condition 99 (corresponding to Tl-tar in FIG. 10) required for transferring red.

[0057] Referring to the left side of FIG. 11 (during low-temperature heating), a first temperature distribution curve 96 exists between a low-temperature boundary condition 99 and a high-temperature boundary condition 98 (second section 94) throughout the entire in-plane direction D6 of the printed pattern 44. On the other hand, a second temperature distribution curve 97 does not reach the high-temperature boundary condition 98 throughout the entire in-plane direction D6 of the printed pattern 44. Referring to FIG. 10, under this condition, the peel force at the second boundary 88 is smallest at any position in the in-plane direction D6 of the printed pattern 44, and therefore peeling occurs at the second boundary 88 throughout the entire in-plane direction D6 of the printed pattern 44. Therefore, red color can be transferred without generating fringes 80.

[0058] Referring to the right side of FIG. 11 , the first temperature distribution curve 96 exceeds the low-temperature boundary condition 99 throughout the entire in-plane direction D6 of the printed pattern 44. Meanwhile, the second temperature distribution curve 97 exceeds the high-temperature boundary condition 98 (third section 95) in the central portion 100, which is prone to relatively high temperatures, but lies between the low-temperature boundary condition 99 and the high-temperature boundary condition 98 (second section 94) in the peripheral portion 101, which is prone to lower temperatures than the central portion 100. In this situation, the peel force at the first boundary portion 87 (between the base layer 35 and the first ink layer 36) is not sufficiently reduced, and the magnitude relationship of the peel force at the peripheral portion 101 becomes the magnitude relationship shown in the second section 94 of FIG. 10 . In other words, the peel force at the second boundary portion 88 is the smallest, and peeling occurs at the second boundary portion 88. This results in a fringe 80 selectively occurring at the peripheral portion 101 of the printed pattern 44.

[0059] Therefore, the inventors of the present invention found that, in order to suppress such fringes 80, the temperature difference between the temperature Th reached at the second boundary 88 and the temperature Tl reached at the third boundary 89 and the temperature difference between the high-temperature boundary condition (Th_tar) and the low-temperature boundary condition (Tl_tar) can be made closer, as shown in FIG. 12 . In other words, they found that the fringes 80 can be suppressed by making |Th - Tl| closer to |(Tl_tar) - (Th_tar)|. More specifically, the thickness of the second ink layer 37 can be adjusted to be small, thereby shortening the heat transfer distance between the second boundary 88 and the third boundary 89 and improving the amount of heat transfer to the third boundary 89. As a result, the peak of the second temperature distribution curve 97 becomes higher relative to the second boundary 88, as shown in FIG. 12 , and therefore |Th - Tl| can be made closer to |(Tl_tar) - (Th_tar)|.

[0060] [Specific configuration of thermal transfer recording medium] Next, an example of the configuration of the thermal transfer recording medium 47 (ink ribbon) that can suppress the occurrence of fringes 80 will be described.

[0061] Fig. 13 is a schematic cross-sectional view showing the layer structure of a thermal transfer recording medium 47 according to an embodiment of the present disclosure, in which the thermal transfer recording medium 47 is adhered to a printer tape 2 as an example of a print-receiving medium.

[0062] The thermal transfer recording medium 47 may be used as the ink ribbon 3 in the printing device 1 and printing process shown in FIGS. 1 to 4A and 4B. The thermal transfer recording medium 47 includes a substrate layer 48, a backing layer 49, a welding layer 70, a first thermal transfer layer 50, an intermediate layer 51, and a second thermal transfer layer 52. The welding layer 70, the first thermal transfer layer 50, the intermediate layer 51, and the second thermal transfer layer 52 are laminated in this order on a front surface 53, which is an example of a first surface, of the substrate layer 48. The surface of the substrate layer 48 opposite the front surface 53 may be a back surface 54. The backing layer 49 is laminated on the back surface 54 of the substrate layer 48. The first thermal transfer layer 50 and the second thermal transfer layer 52 may be referred to as a first ink layer and a second ink layer, respectively.

[0063] The thermal transfer recording medium 47 of the present disclosure is characterized in that it includes a substrate layer 48 and a welding layer 70, a first thermal transfer layer 50, an intermediate layer 51, and a second thermal transfer layer 52, which are laminated in this order on a surface 53 of the substrate layer 48 and in direct contact with each other. The intermediate layer 51 contains a thermoplastic elastomer as a binder. The intermediate layer 51 may be omitted.

[0064] The specific compositions and physical properties of the substrate layer 48, backing layer 49, welding layer 70, first thermal transfer layer 50, intermediate layer 51, and second thermal transfer layer 52 contained in the thermal transfer recording medium 47 will be described in detail below.

[0065] (1) Base material layer 48 Examples of the substrate layer 48 include resin films such as polysulfone, polystyrene, polyamide, polyimide, polycarbonate, polypropylene, polyester, and triacetate; thin paper such as condenser paper and glassine paper; and cellophane. Among these, polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate are preferred from the standpoints of mechanical strength, dimensional stability, heat treatment resistance, and cost. The thickness of the substrate layer 48 can be set arbitrarily depending on, for example, the specifications of the thermal transfer printer. For example, the thickness of the substrate layer 48 is 1 μm or more, preferably 2 μm or more. For example, the thickness of the substrate layer 48 is 10 μm or less, preferably 8 μm or less. For example, the thickness of the substrate layer 48 is 1 μm or more and 10 μm or less, preferably 2 μm or more and 8 μm or less.

[0066] (2) Back layer 49 The back surface layer 49 improves the heat resistance, slipperiness, abrasion resistance, etc. of the back surface 54 of the base material layer 48 that comes into contact with the thermal head 6. Examples of materials for the back surface layer 49 include silicone resin, fluororesin, silicone-fluorine copolymer resin, nitrocellulose resin, silicone-modified urethane resin, and silicone-modified acrylic resin. The back surface layer 49 may contain a lubricant as needed.

[0067] The back surface layer 49 can be formed, for example, by applying a coating material in which the above-mentioned resin or the like is dissolved or dispersed in an arbitrary solvent to the back surface 54 of the base material layer 48 and then drying the coating material. The thickness of the back surface layer 49 can be set as desired depending on, for example, the specifications of the thermal transfer printer. The thickness of the back surface layer 49 can be adjusted by the amount of the back surface layer 49 applied.

[0068] For example, the coating amount of the back layer 49 is 0.05 g / m 2 in terms of the amount of solid content per unit area. 2 or more, preferably 0.1 g / m 2 For example, the coating amount of the back layer 49 is 0.5 g / m2 in terms of the amount of solid content per unit area. 2 or less, preferably 0.4 g / m 2For example, the coating amount of the back layer 49 is 0.05 g / m2 in terms of the amount of solid content per unit area. 2 More than 0.5g / m 2 or less, preferably 0.1 g / m 2 More than 0.4g / m 2 The specific thickness of the back surface layer 49 may be, for example, 0.05 μm or more and 0.5 μm or less, and preferably 0.1 μm or more and 0.4 μm or less.

[0069] (3) Welding layer 70 The welding layer 70 contains at least one resin selected from the group consisting of polyamide resin, polyester resin, epoxy resin, phenol resin, and polyvinyl alcohol resin. In order to improve the affinity and adhesion of the welding layer 70 to the base layer 48 and the first thermal transfer layer 50 during low-temperature heating, it is preferable to form the welding layer 70 using a polyamide resin.

[0070] Examples of polyamide resins include polyamides obtained by polycondensation of lactams with three or more ring members, polymerizable aminocarboxylic acids, dibasic acids and diamines or their salts, or mixtures thereof. These polyamide resins can be used alone or in combination of two or more.

[0071] Specific examples of commercially available polyamide resins include the TOMAID (registered trademark) series manufactured by T&K TOKA Corporation, such as 1310 (softening point: 120±5°C, melt viscosity: 1500 to 4500 mPa·s / 200°C), 1315 (softening point: 130±5°C, melt viscosity: 7000 to 18000 mPa·s / 200°C), and 1320 (softening point: 100±5°C, melt viscosity: 11000 to 20000 mPa·s / 200°C)], 1340 [softening point: 140±5°C, melt viscosity: 8000 to 16000 mPa·s / 200°C], TXC-243A [softening point: 105±5°C, melt viscosity: 5000 to 10000 mPa·s / 200°C], TXC-245A [softening point: 90±5°C, melt viscosity: 1000 to 2000 mPa·s / 200°C], etc.

[0072] In this application, when comparing temperatures related to thermal deformation of multiple substances, the softening point is used as the comparison temperature for substances that have a softening point, such as polyamide resins. For substances that have a melting point (such as wax, which will be described later), the melting point is used as the comparison temperature. For substances that do not have either a melting point or a softening point but have a glass transition temperature (such as polyester resins, which will be described later), the glass transition temperature is used as the comparison temperature.

[0073] Specific examples of commercially available polyester resins include UE-3320, UE-9820, UE-3350, and UE-3380 from the Elitel (registered trademark) series manufactured by Unitika Ltd., and 200 (glass transition temperature: 67°C), 600 (glass transition temperature: 47°C), GK-360 (glass transition temperature: 56°C), GK-810 (glass transition temperature: 46°C), and GK-680 (glass transition temperature: 10°C) from the Vylon (registered trademark) series manufactured by Toyobo Co., Ltd.

[0074] Specific examples of commercially available epoxy resins include the basic solid types of epoxy resins in the JER (registered trademark) series manufactured by Mitsubishi Chemical Corporation, such as 1001 [softening point (ring and ball method): 64°C, number average molecular weight Mn: about 900], 1002 [softening point (ring and ball method): 78°C, number average molecular weight Mn: about 1200], 1003 [softening point (ring and ball method): 89°C, number average molecular weight Mn: about 1300], 1055 [softening point (ring and ball method): 93°C, number average molecular weight Mn: about 1600], 1004 [softening point (ring and ball method): 97°C, number average molecular weight Mn: about 1650], and 1004AF [softening point ( Ring and ball method): 97℃, number average molecular weight Mn: approx. 1650〕, 1007 [Softening point (ring and ball method): 128℃, number average molecular weight Mn: approx. 2900〕, 10 09 [Softening point (ring and ball method): 144℃, number average molecular weight Mn: about 3800], 1010 [number average molecular weight Mn: about 5500], 1003F [softening point (Ring and ball method): 96°C], 1004F [Softening point (ring and ball method): 103°C], 1005F, 1009F [Softening point (ring and ball method): 144°C], 100 4FS [Softening point (ring and ball method): 100℃], 1006FS [Softening point (ring and ball method): 112℃], 1007FS [Softening point (ring and ball method): 124℃].

[0075] Specific examples of commercially available phenolic resins include, for example, TD-2131 (softening point: 78 to 82°C), TD-2106 (softening point: 88 to 95°C), TD-2093 (softening point: 98 to 102°C), and TD-2090 (softening point: 117 to 123°C) from the Phenolite (registered trademark) series manufactured by DIC Corporation, and BRG-555 (softening point: 66 to 72°C, melt viscosity: 0.3 to 0.5 Pa·s / 125°C) and BRG- 556 [softening point: 77 to 83°C, melt viscosity: 0.1 to 0.3 Pa·s / 150°C], BRG-557 [softening point: 82 to 88°C, melt viscosity: 0.2 to 0.4 Pa·s / 150°C], BRG-558 [softening point: 93 to 98°C, melt viscosity: 0.8 to 1.2 Pa·s / 150°C], CRG-951 [softening point: 93 to 99°C, melt viscosity: 0.2 to 0.8 Pa·s / 150°C], and TAM-005 [softening point: 80 to 88°C, melt viscosity: 0.3 to 0.5 Pa·s / 150°C].

[0076] The polyvinyl alcohol resin is preferably, for example, a partially saponified polyvinyl alcohol resin having a degree of saponification of 90 or less. The degree of polymerization of the polyvinyl alcohol resin is, for example, 2000 or less, and preferably about 500. Specific commercially available polyvinyl alcohol resins include, for example, B-05 [saponification degree: 86.5 to 89.5 mol%, degree of polymerization: about 500, viscosity (4%, 20°C): 5.0 to 6.0 mPa·s], B-17 [saponification degree: 87.0 to 89.0 mol%, degree of polymerization: about 1600, viscosity (4%, 20°C): 21 to 25 mPa·s], and B-20 [saponification degree: 87.0 to 89.0 mol%, degree of polymerization: about 2000] from the Denka Poval (registered trademark) series manufactured by Denka Co., Ltd. and from the Kuraray Poval (registered trademark) series manufactured by Kuraray Co., Ltd., examples include 48-80 [degree of saponification: 78.5 to 80.5 mol%, viscosity (4%, 20°C): 45.0 to 51.0 mPa·s], 3-88 [degree of saponification: 87.0 to 89.0 mol%, viscosity (4%, 20°C): 3.2 to 3.6 mPa·s], and 5-88 [degree of saponification: 86.5 to 89.0 mol%, viscosity (4%, 20°C): 4.6 to 5.4 mPa·s].

[0077] The softening point of the polyamide resin used in the welding layer 70 is, for example, 90° C. or higher, preferably 110° C. or higher, and more preferably 125° C. or higher. If the softening point is within this range, the resin hardly softens at the relatively low temperatures that occur during low-temperature transfer, and high adhesive strength can be maintained between the base layer 48 and the first thermal transfer layer 50.

[0078] The welding layer 70 can be formed, for example, by applying a coating material in which the forming material for the welding layer 70 is dissolved or dispersed in any solvent onto the surface 53 of the base layer 48 and then drying it.

[0079] (4) First thermal transfer layer 50 The first thermal transfer layer 50 can be formed, for example, from any thermoplastic resin. Considering the need to improve the affinity and adhesive strength for the welding layer 70 and intermediate layer 51, it is preferable to form the first thermal transfer layer 50 using an epoxy resin as the thermoplastic resin. Epoxy resins have excellent affinity and adhesive strength for the thermoplastic elastomer that forms the base layer 48, which is made of a polyester film such as PET, and the intermediate layer 51. The first thermal transfer layer 50 can be formed using an epoxy resin that does not contain (excludes) a curing agent as the thermoplastic resin.

[0080] Examples of epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, alicyclic epoxy resins, hydrogenated bisphenol A epoxy resins, hydrogenated bisphenol AD ​​epoxy resins, aliphatic epoxy resins such as propylene glycol glycoxyl ether and pentaerythritol polyglycidyl ether, epoxy resins obtained from aliphatic or aromatic amines and epichlorohydrin, epoxy resins obtained from aliphatic or aromatic carboxylic acids and epichlorohydrin, heterocyclic epoxy resins, spiro ring-containing epoxy resins, epoxy-modified resins, and brominated epoxy resins. Specific examples of epoxy resins include, but are not limited to, the following epoxy resins. These epoxy resins can be used alone or in combination of two or more.

[0081] Among the JER (registered trademark) series epoxy resins manufactured by Mitsubishi Chemical Corporation, the basic solid types are 1001 [softening point (ring and ball method): 64°C, number average molecular weight Mn: approximately 900], 1002 [softening point (ring and ball method): 78°C, number average molecular weight Mn: approximately 1200], 1003 [softening point (ring and ball method): 78°C, number average molecular weight Mn: approximately 1200], Softening point (ring and ball method): 89℃, number average molecular weight Mn: approx. 1300], 1055 [softening point (ring and ball method): 93℃, number average molecular weight Mn: approx. 160 0], 1004 [Softening point (ring and ball method): 97℃, number average molecular weight Mn: about 1650], 1004AF [Softening point (ring and ball method): 97℃, number average Molecular weight Mn: about 1650], 1007 [softening point (ring and ball method): 128℃, number average molecular weight Mn: about 2900], 1009 [softening point (ring and ball method) method): 144℃, number average molecular weight Mn: approximately 3800], 1010 [number average molecular weight Mn: approximately 5500], 1003F [softening point (ring and ball method): 96℃], 1004F [Softening point (ring and ball method): 103℃], 1005F, 1009F [Softening point (ring and ball method): 144℃], 1004FS [Softening point (ring and ball method): 100℃], 1006FS [Softening point (ring and ball method): 112℃], 1007FS [Softening point (ring and ball method): 124℃].

[0082] The softening point of the epoxy resin used in the first thermal transfer layer 50 is, for example, 95° C. or higher, preferably 110° C. or higher, and more preferably 125° C. or higher.

[0083] The first thermal transfer layer 50 may contain an adhesive in addition to the epoxy resin. The inclusion of an adhesive can further improve the affinity and adhesion to the welding layer 70 and the intermediate layer 51. Examples of adhesives include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives.

[0084] Considering the affinity and compatibility with the epoxy resin, and the affinity and adhesion to the welding layer 70 and intermediate layer 51, an acrylic adhesive is preferred as the adhesive. Specific examples of the acrylic adhesive include, but are not limited to, the following acrylic adhesives. These acrylic adhesives can be used alone or in combination of two or more.

[0085] Among the Olivine (registered trademark) BPS (solvent-based) series manufactured by Toyochem Co., Ltd., BPS1109 (non-volatile content: 39.5% by mass), BPS3156D (non-volatile content: 34% by mass), BPS4429-4 (non-volatile content: 45% by mass), BPS4849-40 (non-volatile content: 40% by mass), BPS5160 (non-volatile content: 33% by mass), BPS5213K (non-volatile content: 35% by mass), BPS5215K (non-volatile content: 39% by mass), BPS5227-1 (non-volatile content: 41.5% by mass), BPS5296 (non-volatile content: 37% by mass), BPS5330 (non-volatile content: 40% by mass), BPS5375 (non-volatile content: 45% by mass), BPS5448 (non-volatile content: 40% by mass), BPS5513 (non-volatile content: 44.5% by mass), BPS55 65K (non-volatile content: 45% by mass), BPS5669K (non-volatile content: 46% by mass), BPS5762K (non-volatile content: 45.5% by mass), BPS5896 (non-volatile content: 37% by mass), BPS5978 (non-volatile content: 35% by mass), BPS6074HTF (non-volatile content: 52% by mass), BPS6080TFK (non-volatile content: 45% by mass), BPS6130TF (non-volatile content: 52% by mass), BPS6153K (non-volatile content: 25% by mass), BPS6163 (non-volatile content: 37% by mass), BPS6231 (non-volatile content: 56% by mass), BPS6421 (non-volatile content: 47% by mass), BPS6430 (non-volatile content: 33% by mass), BPS6574 (non-volatile content: 57% by mass), BPS8170 (non-volatile content: 36.5% by mass), BPS HS-1 (non-volatile content: 40% by mass).

[0086] Among the solvent-based adhesives (removable) manufactured by Lion Specialty Chemicals Co., Ltd., the following are used: AS-325 (solid content: 45% by mass), AS-375 (solid content: 45% by mass), AS-409 (solid content: 45% by mass), AS-417 (solid content: 45% by mass), AS-425 (solid content: 45% by mass), AS-455 (solid content: 45% by mass), AS-665 (solid content: 40% by mass), AS-1107 (solid content: 43% by mass), and AS-4005 (solid content: 45% by mass).

[0087] The acrylic adhesive used in the first thermal transfer layer 50 may be used in combination with a tackifier. This is because, for example, it is possible to improve the sharpness of the first thermal transfer layer 50, suppress excess peeling, and improve the clarity of the recorded characters. Examples of tackifiers include ester gum, terpene phenol resin, and rosin ester. Specific examples of tackifiers are not particularly limited, but include the following various tackifiers. These tackifiers can be used alone or in combination of two or more types.

[0088] Among the terpene phenol resins in the YS Polyster series manufactured by Yasuhara Chemical Co., Ltd., U130 (softening point: 130±5°C), U115 (softening point: 115±5°C), T160 (softening point: 160±5°C), T145 (softening point: 145±5°C), T130 (softening point: 130±5°C), T115 (softening point: 115± 5℃), T100 (softening point: 100±5℃), T80 (softening point: 80±5℃), S145 (softening point: 145±5℃), G150 (softening point: 150±5℃) , G125 (softening point: 125±5℃), N125 (softening point: 125±5℃), K125 (softening point: 125±5℃), TH130 (softening point: 130±5℃).

[0089] Among the ester gums manufactured by Arakawa Chemical Co., Ltd., AA-G [softening point (ring and ball method): 82~88℃], AA-L [softening point (ring and ball method): 82~88℃], AA-V [softening point (ring and ball method): 82~95℃] , 105 [Softening point (ring and ball method): 100~110℃], AT [Viscosity: 20000~40000mPa·s], H [Softening point (ring and ball method): 68~75℃], HP [Softening point (ring and ball method): 80℃ or higher].

[0090] Among the rosin esters in the Pencel (registered trademark) series manufactured by Arakawa Chemical Industries, Ltd., GA-100 [softening point (Ring and Ball method): 100 to 110°C], AZ [softening point (Ring and Ball method): 95 ~105℃], C [Softening point (ring and ball method): 117~127℃], D-125 [Softening point (ring and ball method): 120~130℃], D-135 [Softening Point (ring and ball method): 130~140℃], D-160 [softening point (ring and ball method): 150~165℃], KK [softening point (ring and ball method): 165℃ or higher].

[0091] The softening point of the tackifier used in the first thermal transfer layer 50 is, for example, 60°C or higher, and preferably 120°C or lower.

[0092] The first thermal transfer layer 50 may contain any colorant. As the colorant, one or more of various colorants can be used depending on the color of the first thermal transfer layer 50. The colorant may be, for example, a pigment. In consideration of improving the weather resistance of the letters, a pigment is preferred as the colorant used in the first thermal transfer layer 50. For example, carbon black is preferred as a pigment for coloring the first thermal transfer layer 50 black. Specific examples of carbon black are not particularly limited, but include, for example, the following various carbon blacks. These carbon blacks can be used alone or in combination of two or more types.

[0093] Mitsubishi Chemical Corporation MA77 powder (LFF, DBP absorption capacity: 68 cm 3 / 100g], MA7 powder [LFF, DBP absorption: 66cm 3 / 100g], MA7 granules [LFF, DBP absorption: 65cm 3 / 100g], MA8 powder [LFF, DBP absorption capacity: 57cm 3 / 100g], MA8 granules [LFF, DBP absorption: 51cm 3 / 100g], MA11 powder [LFF, DBP absorption: 64cm 3 / 100g], MA100 powder [LFF, DBP absorption capacity: 100cm 3 / 100g], MA100 granules [LFF, DBP absorption: 95cm 3 / 100g], MA100R powder [LFF, DBP absorption capacity: 100cm 3 / 100g], MA100R granules [LFF, DBP absorption: 95cm 3 / 100g], MA100S powder [LFF, DBP absorption capacity: 100cm 3 / 100g], MA230 powder [LFF, DBP absorption: 113cm 3 / 100g], MA220 powder [LFF, DBP absorption: 93cm 3 / 100g], MA14 powder [LFF, DBP absorption: 73cm 3 / 100g].

[0094] Mitsubishi Chemical Corporation #3030B (furnace method, DBP absorption: 130 cm 3 / 100g), #3040B (furnace method, DBP absorption: 114cm 3 / 100g), #3050B (furnace method, DBP absorption: 175cm 3 / 100g), #3230B (furnace method, DBP absorption: 140cm 3 / 100g), #3350B (furnace method, DBP absorption: 164cm 3 / 100g), #3400B (furnace method, DBP absorption: 175cm 3 / 100g).

[0095] Tokai Carbon Co., Ltd.'s Toka Black (registered trademark) series, #5500 (furnace method, DBP absorption: 155 cm 3 / 100g), #4500 (furnace method, DBP absorption: 168cm 3 / 100g), #4400 (furnace method, DBP absorption: 135cm 3 / 100g), #4300 (furnace method, DBP absorption: 142cm 3 / 100g).

[0096] Orion Engineered Carbons' PRINTEX (registered trademark) series L (furnace method, DBP absorption: 120 cm 3 / 100g), L6 (furnace method, DBP absorption: 126cm 3 / 100g).

[0097] Birla Carbon's CONDUCTEX (registered trademark) series, 975 (furnace method, 170 cm 3 / 100g), SC (furnace method, 115cm 3 / 100g).

[0098] Among the VULCAN (registered trademark) series manufactured by CABOT, XC72 (furnace method, DBP absorption: 174 cm 3 / 100g), 9A32 (furnace method, DBP absorption: 114cm 3 / 100g), and 3700 of the company's BLACK PEARLS series (furnace method, DBP absorption: 111cm 3 / 100g).

[0099] Among the Denka Black (registered trademark) series manufactured by Denka Co., Ltd., Denka Black granules (acetylene method, DBP absorption: 160 cm 3 / 100g), FX-35 (acetylene method, DBP absorption: 220cm 3 / 100g), HS-100 (acetylene method, DBP absorption: 140cm 3 / 100g).

[0100] Among the KETJENBLACK (registered trademark) series manufactured by Lion Specialty Chemicals Co., Ltd., EC300J (gasification method, DBP absorption capacity: 360 cm 3 / 100g), EC600DJ (gasification method, DBP absorption capacity: 495cm 3 / 100g).

[0101] The ratio of each component in the first thermal transfer layer 50 is not particularly limited. The ratio of the acrylic adhesive to 100 parts by mass of the epoxy resin is, for example, 30 parts by mass or more, and preferably 40 parts by mass or more. The ratio of the acrylic adhesive to 100 parts by mass of the epoxy resin is, for example, 150 parts by mass or less, and preferably 100 parts by mass or less. The ratio of the acrylic adhesive to 100 parts by mass of the epoxy resin is, for example, 30 parts by mass or more and 150 parts by mass or less, and preferably 40 parts by mass or more and 100 parts by mass or less.

[0102] The ratio of the tackifier to 100 parts by mass of the epoxy resin is, for example, 3 parts by mass or more, and preferably 5 parts by mass or more. The ratio of the tackifier to 100 parts by mass of the epoxy resin is, for example, 150 parts by mass or less, and preferably 100 parts by mass or less. The ratio of the tackifier to 100 parts by mass of the epoxy resin is, for example, 3 parts by mass or more and 150 parts by mass or less, and preferably 5 parts by mass or more and 100 parts by mass or less.

[0103] The ratio of the colorant such as carbon black to 100 parts by mass of the epoxy resin is, for example, 100 parts by mass or more, preferably 130 parts by mass or more. The ratio of the colorant to 100 parts by mass of the epoxy resin is, for example, 230 parts by mass or less, preferably 200 parts by mass or less. The ratio of the colorant to 100 parts by mass of the epoxy resin is, for example, 100 parts by mass or more and 230 parts by mass or less, preferably 130 parts by mass or more and 200 parts by mass or less.

[0104] Furthermore, for components contained in the first thermal transfer layer 50 that are supplied in liquid form dissolved or dispersed in an arbitrary solvent, the amount of active ingredient can be adjusted so that the proportion of the active ingredient falls within the above range (the same applies below).

[0105] The first thermal transfer layer 50 can be formed, for example, by applying a coating material in which the above components are dissolved or dispersed in a solvent directly onto the welding layer 70 and then drying the coating material. In this disclosure, as shown in Figures 5A and 5B, the characters to be recorded on the printer tape 2 are color-coded. For this color coding, considering adjustment of the adhesion between the first thermal transfer layer 50 and the welding layer 70 and other layers, it is preferable to form the first thermal transfer layer 50 directly on the welding layer 70.

[0106] (5) Middle class 51 As described above, the intermediate layer 51 contains a thermoplastic elastomer. In particular, the intermediate layer 51 is preferably formed solely from a thermoplastic elastomer. The thermoplastic elastomer forming the intermediate layer 51 preferably contains at least one of a styrene-based thermoplastic elastomer and an acetate-based thermoplastic elastomer.

[0107] Examples of styrene-based thermoplastic elastomers include styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene / ethylene-propylene-styrene block copolymer (SEEPS), styrene-isoprene-styrene block copolymer (SIS), etc. Examples of acetate-based thermoplastic elastomers include ethylene-vinyl acetate copolymer (EVA).

[0108] The styrene content of the thermoplastic elastomer contained in the intermediate layer 51 is, for example, 10% by mass or more and 70% by mass or less, and preferably 15% by mass or more and 50% by mass or less. If the styrene content is too high, the rubber-like elasticity of the intermediate layer 51 decreases, and during low-temperature transfer, the adhesive strength to the first thermal transfer layer 50 and the second thermal transfer layer 52 may not be maintained, or the color of the characters may become cloudy. If the styrene content is too low, the rubber-like elasticity of the intermediate layer 51 becomes too high, and the second thermal transfer layer 52 may not be peeled off during high-temperature transfer, and the color of the characters may become cloudy.

[0109] The thermoplastic elastomer contained in the intermediate layer 51 has a melt mass flow rate (hereinafter sometimes abbreviated simply as "MFR") of, for example, 1000 g / 10 min or less, and preferably 400 g / 10 min or less. The MFR may be, for example, the MFR determined by the measurement method specified in ISO 1133-1:2011, at a temperature of 190°C and a load of 2.16 kg. Hereinafter, unless otherwise specified, the conditions for measuring the MFR are a temperature of 190°C and a load of 2.16 kg.

[0110] Thermoplastic elastomers with an MFR greater than 400 g / 10 min tend to have too strong an affinity with the second thermal transfer layer 52. As a result, the second thermal transfer layer 52 may not peel off during high-temperature transfer, causing the color of the characters to become cloudy. Furthermore, the entire thermal transfer recording medium 47, i.e., the substrate layer 48, first thermal transfer layer 50, intermediate layer 51, and second thermal transfer layer 52, may stick to the printing surface 31 of the printer tape 2. Thermoplastic elastomers with an MFR greater than 400 g / 10 min have low melt viscosity and high fluidity, so they may not be able to maintain adhesion to the first thermal transfer layer 50 and second thermal transfer layer 52 during low-temperature transfer, or the color of the characters may become cloudy.

[0111] In contrast, if a thermoplastic elastomer has an MFR of 400 g / 10 min or less, problems that can occur when using a thermoplastic elastomer with an MFR exceeding 400 g / 10 min can be suppressed. Furthermore, even when thermal transfer recording is performed continuously, the colors on the printing surface 31 of the printer tape 2 are not easily clouded, the two colors are clearly separated, and characters can be recorded with excellent clarity without residual peeling. To further enhance these effects, it is preferable that the MFR of the thermoplastic elastomer be 2.5 g / 10 min or less, especially 2.3 g / 10 min or less, even within the above range.

[0112] There is no particular lower limit for the MFR, and thermoplastic elastomers that show "No Flow" when measured at the aforementioned temperature of 190°C and load of 2.16 kg can be used. Specific examples of thermoplastic elastomers include, but are not limited to, the following thermoplastic elastomers. These thermoplastic elastomers can be used alone or in combination of two or more.

[0113] Among the SEBS in the Tuftec (registered trademark) series manufactured by Asahi Kasei Corporation, the following are used: H1521 (MFR: 2.3 g / 10 min), H1051 (MFR: less than 0.8 g / 10 min), H1052 (MFR: less than 13.0 g / 10 min), H1272 (MFR: No Flow), P1083 (MFR: 3.0 g / 10 min), P1500 (MFR: 4.0 g / 10 min), P5051 (MFR: 3.0 g / 10 min), and P2000 (MFR: 3.0 g / 10 min).

[0114] Among the SBSs in the Tufprene (registered trademark) series manufactured by Asahi Kasei Corporation, A [MFR: 2.6 g / 10 min], 125 [MFR: 4.5 g / 10 min], and 126S [MFR: 4.5 g / 10 min].

[0115] Among the SBSs in the Asaprene (registered trademark) T series manufactured by Asahi Kasei Corporation, T-411 [MFR: No Flow], T-432 [MFR: No Flow], T-437 [MFR: No Flow], T-438 [MFR: No Flow], and T-439 [MFR: No Flow].

[0116] Among the SEPS in the Septon (registered trademark) series manufactured by Kuraray Co., Ltd., the following were measured: 2002 (MFR: 70 g / 10 min), 2004F (MFR: 5 g / 10 min), 2005 (MFR: No Flow), 2006 (MFR: No Flow), 2063 (MFR: 7 g / 10 min), and 2104 (MFR: 0.4 g / 10 min). The MFR of these SEPS was measured under the following conditions: a temperature of 230°C and a load of 2.16 kg.

[0117] Among the SEEPS in the Septon (registered trademark) series manufactured by Kuraray Co., Ltd., the following are listed: 4033 (MFR: <0.1 g / 10 min), 4044 (MFR: No Flow), 4055 (MFR: No Flow), 4077 (MFR: No Flow), and 4099 (MFR: No Flow). The MFR measurement conditions for these SEEPS are a temperature of 230°C and a load of 2.16 kg.

[0118] Among the vinyl SISs in the Hybra (registered trademark) series manufactured by Kuraray Co., Ltd., 5125 [MFR: 4g / 10min] and 5127 [MFR: 5 / 10min].

[0119] Among the Ultrathene (registered trademark) series EVA manufactured by Tosoh Corporation, 514R (MFR: 0.41 g / 10 min), 515 (MFR: 2.5 g / 10 min), 510 (MFR: 2.5 g / 10 min), 510F (MFR: 2.5 g / 10 min), 520F (MFR: 2.0 g / 10 min), 540 (MFR: 3.0 g / 10 min), 540F (MFR: 3.0 g / 10 min) in], 537 [MFR:8.5g / 10min], 537L [MFR:8.5g / 10min], 537S-2 [MFR:8.5g / 10min], 541 [MFR:9.0g / 10min] , 541L [MFR:9.0g / 10min], 530 [MFR:75g / 10min], 526 [MFR:25g / 10min], 630 [MFR:1.5g / 10min], 631 [MFR :1.5g / 10min〕, 636〔MFR:2.5g / 10min〕, 625〔MFR:14g / 10min〕, 626〔MFR:3.0g / 10min〕, 627〔MFR:0.8g / 1 0min], 633 [MFR:20g / 10min], 635 [MFR:2.4g / 10min], 640 [MFR:2.8g / 10min], 634 [MFR:4.3g / 10min], 68 0 [MFR:160g / 10min], 681 [MFR:350g / 10min], 751 [MFR:5.7g / 10min], 710 [MFR:18g / 10min], 720 [MFR:15] 0g / 10min〕, 722〔MFR:400g / 10min〕, 750〔MFR:30g / 10min〕, 752〔MFR:60g / 10min〕, 760〔MFR:70g / 10min〕.

[0120] The intermediate layer 51 may be made of a thermoplastic elastomer, a polyolefin resin, a long-chain alkyl resin, or the like.

[0121] Examples of polyolefin resins include Surflen (registered trademark) P-1000 manufactured by Mitsubishi Chemical Corporation. Examples of long-chain alkyl resins include 1010, 1010S, 1050, 1070, and 406 from the P-LOIL (registered trademark) series manufactured by Lion Specialty Chemicals Co., Ltd.

[0122] The intermediate layer 51 can be formed, for example, by applying a coating material in which the forming material for the intermediate layer 51 is dissolved or dispersed in any solvent onto the first thermal transfer layer 50 and then drying it.

[0123] (6) Second thermal transfer layer 52 The second thermal transfer layer 52 can be formed, for example, from any thermoplastic resin. Examples of thermoplastic resins used for the second thermal transfer layer 52 include epoxy resin, polyester resin, and polyolefin resin. The thermoplastic resin can be selected appropriately depending on the material from which the printer tape 2 is formed. When the first thermal transfer layer 50 is formed from an epoxy resin, it is preferable that the second thermal transfer layer 52 is also formed from an epoxy resin.

[0124] By forming the second thermal transfer layer 52 from an epoxy resin, the adhesive strength of the first thermal transfer layer 50 to the welding layer 70 and intermediate layer 51 can be balanced against the adhesive strength of the second thermal transfer layer 52 to the printer tape 2. This allows the first thermal transfer layer 50 and the intermediate layer 51 to be effectively separated toward the base layer 48, and the second thermal transfer layer 52 to be effectively separated toward the printer tape 2, during low-temperature transfer. Examples of epoxy resins that can be used include the various epoxy resins exemplified as epoxy resins for the first thermal transfer layer 50. These epoxy resins can be used alone or in combination of two or more types.

[0125] The second thermal transfer layer 52 may contain wax in addition to the thermoplastic resin. The inclusion of wax allows the first thermal transfer layer 50 and the intermediate layer 51 to be easily separated from each other on the substrate layer 48 side, and the second thermal transfer layer 52 to be easily separated from each other on the printer tape 2 side, during low-temperature transfer.

[0126] Any wax that has affinity or compatibility with thermoplastic resins such as epoxy resins can be used as the wax. For example, natural waxes such as carnauba wax, paraffin wax, and microcrystalline wax, and synthetic waxes such as Fischer-Tropsch wax can be used. Specific examples of waxes are not particularly limited, but include, for example, carnauba wax No. 1 flake, No. 2 flake, No. 3 flake, No. 1 powder, and No. 2 powder manufactured by Toyochem Co., Ltd. (all of which have a melting point of 80 to 86°C), and paraffin waxes such as EMUSTAR-1155 (melting point: 69°C), EMUSTAR-0135 (melting point: 60°C), and EMUSTAR-0136 (melting point: 60°C) manufactured by Nippon Seiro Co., Ltd. Examples of suitable waxes include microcrystalline waxes manufactured by Nippon Seiro Co., Ltd., such as EMUSTAR-0001 (melting point: 84°C) and EMUSTAR-042X (melting point: 84°C), and Fischer-Tropsch waxes manufactured by Nippon Seiro Co., Ltd., such as FNP-0090 (freezing point: 90°C), SX80 (freezing point: 83°C), FT-0165 (melting point: 73°C), and FT-0070 (melting point: 72°C). These waxes can be used alone or in combination of two or more.

[0127] The second thermal transfer layer 52 may contain any colorant. As the colorant, one or more of various colorants can be used depending on the color of the second thermal transfer layer 52. The colorant may be, for example, a pigment. In consideration of improving the weather resistance of the letters, a pigment is preferred as the colorant used in the second thermal transfer layer 52. For example, the following various red pigments can be used as pigments for coloring the second thermal transfer layer 52 red. These red pigments can be used alone or in combination of two or more.

[0128] CI Pigment Red 5, 7, 9, 12, 48(Ca), 48(Mn), 49, 52, 53, 53:1, 57(Ca), 57:1, 97, 112, 122, 123, 149, 168, 177, 178, 179, 184, 202, 206, 207, 209, 242, 254, 255.

[0129] The ratio of each component in the second thermal transfer layer 52 is not particularly limited. The ratio of wax to 100 parts by mass of epoxy resin is, for example, 3 parts by mass or more, and preferably 5 parts by mass or more. The ratio of wax to 100 parts by mass of epoxy resin is, for example, 11 parts by mass or less, and preferably 9 parts by mass or less. The ratio of wax to 100 parts by mass of epoxy resin is, for example, 3 parts by mass or more and 11 parts by mass or less, and preferably 5 parts by mass or more and 9 parts by mass or less.

[0130] The ratio of the colorant such as a red pigment to 100 parts by mass of the epoxy resin is, for example, 70 parts by mass or more, and preferably 80 parts by mass or more. The ratio of the colorant such as a red pigment to 100 parts by mass of the epoxy resin is, for example, 140 parts by mass or less, and preferably 120 parts by mass or less. The ratio of the colorant such as a red pigment to 100 parts by mass of the epoxy resin is, for example, 70 parts by mass or more and 140 parts by mass or less, and preferably 80 parts by mass or more and 120 parts by mass or less.

[0131] The second thermal transfer layer 52 can be formed, for example, by applying a coating material in which the above components are dissolved or dispersed in an arbitrary solvent onto the intermediate layer 51 and then drying the coating material.

[0132] In the thermal transfer recording medium 47, for example, the amount of energy applied to the thermal head 6 (see FIGS. 1 and 3) may be set low to perform thermal transfer at a relatively low temperature. In this case, in this embodiment, the second thermal transfer layer 52 softens and its adhesion to the base layer 48 decreases. Meanwhile, the adhesion between the first thermal transfer layer 50 and the second thermal transfer layer 52 decreases. In this case, the welding layer 70 has a high softening point, so it hardly softens and maintains high adhesion between the base layer 48 and the first thermal transfer layer 50. As a result, during thermal transfer, only the second thermal transfer layer 52 is thermally transferred to the printing surface 31 of the printer tape 2, while the first thermal transfer layer 50 and the intermediate layer 51 remain on the base layer 48 side (reverse transfer). Therefore, the characters recorded on the printing surface 31 of the printer tape 2 will be the color of the second thermal transfer layer 52, for example, red.

[0133] On the other hand, the thermal transfer recording medium 47 may be thermally transferred at a higher temperature by applying a higher amount of energy to the thermal head 6. In this case, the welding layer 70 further softens, significantly reducing the adhesive strength between it and, for example, the base layer 48. As a result, the entire thermal transfer layer, i.e., the welding layer 70, first thermal transfer layer 50, intermediate layer 51, and second thermal transfer layer 52, are thermally transferred integrally onto the printing surface 31 of the printer tape 2. The characters recorded on the printing surface 31 of the printer tape 2 will have the color of the first thermal transfer layer 50, which is the outermost layer after transfer, for example, black.

[0134] As a result, a two-color pattern, for example, black and red, can be printed using a general-purpose thermal transfer printer that is compatible with two-color printing.

[0135] Therefore, according to the present disclosure, even when a general-purpose thermal transfer printer capable of two-color recording is used to perform continuous thermal transfer recording, the colors are not easily mixed and are clearly separated into two colors, and characters with excellent clarity can be recorded without causing residual peeling.

[0136] [Thickness of each layer of thermal transfer recording medium 47] One of the features of the thermal transfer recording medium 47 according to one embodiment of the present disclosure is that the total thickness of the transferred material separated from the base layer 48 by thermal transfer during low-temperature heating is thinner than that of the first thermal transfer layer 50. Below, the heating and cooling steps shown in Figures 1 to 4A and 4B will be described in detail, and the thickness features of the thermal transfer recording medium 47 will be mentioned.

[0137] FIG. 14 is a diagram showing the relationship between the elapsed time and the temperature reached by the thermal transfer recording medium 47 in the heating and cooling steps shown in FIGS. 1 to 4A and 4B.

[0138] The horizontal axis in FIG. 14 represents the elapsed time of the printing process of the printer 1. t0 represents the start of printing, t1 represents the end of heating by the thermal head 6, and t2 represents the time when the ink ribbon reaches the ink ribbon peeling member 13. The vertical axis in FIG. 14 represents the temperature reached by the thermal transfer recording medium 47. The temperature reached by the thermal transfer recording medium 47 can be defined as the temperature of the thermal transfer recording medium 47 that changes due to external factors. Such external factors may include, for example, heating by the thermal head 6, natural cooling of the thermal transfer recording medium 47 while it is being transported, etc.

[0139] 14, in the printing device 1, the control circuit 22 controls the temperature output (temperature energy) of the thermal head 6, thereby controlling the temperature reached by the thermal transfer recording medium 47. For example, a relatively low first amount of energy is applied to the thermal head 6 in the heating process. In this case, the temperature of the thermal transfer recording medium 47 is determined by the temperature T of the thermal transfer recording medium 47 relative to the ambient temperature (for example, room temperature) around the thermal transfer recording medium 47, as shown by the first temperature curve 55 in the dashed dotted line. E It increases exponentially from T R1 to reach.

[0140] Achieved temperature T R1 may be defined as a temperature equal to or higher than the first temperature T1 and equal to or lower than the second temperature T2. For example, the first temperature T1 is equal to or higher than 60°C and equal to or lower than 120°C, and preferably equal to or higher than 70°C and equal to or lower than 90°C. For example, the second temperature T2 is equal to or higher than 80°C and equal to or lower than 180°C, and preferably equal to or higher than 130°C and equal to or lower than 150°C. The reached temperature T R1 can be set appropriately depending on the output setting method of the thermal head 6 of the printing device 1 used. For example, the target temperature may be set in association with quantitative parameters such as the voltage or current supplied to the heating element 20 of the thermal head 6, the power-on time, etc. Alternatively, the target temperature may be set in association with a relative value to a predetermined reference value (for example, a value before power-on of 0 (zero)).

[0141] On the other hand, in the heating step, a second energy amount relatively higher than the first energy amount is applied to the thermal head 6. In this case, the temperature of the thermal transfer recording medium 47 is, as shown by the second temperature curve 56 in solid line, equal to the ambient temperature T E It increases exponentially from T R2 The temperature reached is T R2 may be defined as the temperature above the second temperature T2.

[0142] After the heating step, the thermal transfer recording medium 47 is naturally cooled in the section up to the ink ribbon peeling member 13 (see also Fig. 3 and Figs. 4A and 4B). In the cooling step, the temperature of the thermal transfer recording medium 47 is cooled to the ultimate temperature T R1 and T R2 It decreases exponentially from T P The temperature reached at this time is T P is the temperature at which a part of the thermal transfer recording medium 47 is peeled off by the ink ribbon peeling member 13, and is therefore the peeling temperature T P The peeling temperature T P is preferably equal to or lower than the third temperature T3. The third temperature T3 is lower than the first temperature T1 (i.e., the first temperature T1 is equal to or higher than the third temperature T3), and is, for example, 40°C to 90°C, and preferably 60°C to 80°C. The magnitudes of the first temperature T1, the second temperature T2, and the third temperature T3 can be set appropriately within the temperature range required for transfer onto the printer tape 2, taking into consideration the chemical composition and physical properties of the ink of the thermal transfer recording medium 47.

[0143] The temperature curve (cooling curve) of the thermal transfer recording medium 47 in the cooling process eventually converges to a constant temperature regardless of which heating control is performed in the heating process, as indicated by the first temperature curve 55 or the second temperature curve 56. Therefore, by ensuring a long cooling process time (t1 → t2), the peeling temperature T Pcan be made substantially the same. To lengthen the cooling process time, for example, the distance between the thermal head 6 and the ink ribbon peeling member 13 (peeling distance L1 in FIG. 1) can be increased. For example, the state of the thermal transfer recording medium 47 after the heating process and the cooling process are performed according to the temperature change shown by the first temperature curve 55 in FIG. 14 may be defined as the first state C1. In contrast, the state of the thermal transfer recording medium 47 after the heating process and the cooling process are performed according to the temperature change shown by the second temperature curve 56 in FIG. 14 may be defined as the second state C2.

[0144] In this way, in the printing device 1, by controlling the temperature output (thermal energy) of the thermal head 6, the start temperature (environment temperature T E ) and final temperature (peeling temperature T P ) is kept constant, the temperature reached by the thermal transfer recording medium 47 can be varied. Taking this temperature control into consideration, for example, by controlling the temperature output of the thermal head 6 in accordance with the physical properties of the base layer 48, backing layer 49, welding layer 70, first thermal transfer layer 50, intermediate layer 51, and second thermal transfer layer 52 of the thermal transfer recording medium 47 in Figure 13, it is expected that the adhesive strength between the layers of the thermal transfer recording medium 47 can be controlled.

[0145] The thermal transfer recording medium 47 has a condition that the sum of the thicknesses of all layers that break and separate from the base layer 48 when in the first state C1 (the sum of the thicknesses of the transferred materials) is thinner than that of the first thermal transfer layer 50. In this embodiment, the above condition can be satisfied by adjusting the thickness of each of the welding layer 70, the first thermal transfer layer 50, the intermediate layer 51, and the second thermal transfer layer 52. The thicknesses of the welding layer 70, the first thermal transfer layer 50, the intermediate layer 51, and the second thermal transfer layer 52 can be confirmed based on, for example, a scanning electron microscope (SEM) image or a transmission electron microscope (TEM) image of the thermal transfer recording medium 47.

[0146] The thickness of the welding layer 70 can be adjusted, for example, by the amount of application of the welding layer 70. For example, the amount of application of the welding layer 70 is 0.1 g / m2 in terms of the amount of solid content per unit area. 2 or more, and preferably 0.2 g / m 2 For example, the coating amount of the welding layer 70 is 1.5 g / m2 in terms of the amount of solid content per unit area. 2 and preferably 1.0 g / m 2 For example, the coating amount of the welding layer 70 is 0.1 g / m2 in terms of the amount of solid content per unit area. 2 More than 1.5g / m 2 or less, preferably 0.2 g / m 2 More than 1.0g / m 2 The specific thickness of the welding layer 70 (before printing) may be, for example, 0.05 μm or more and 1.5 μm or less, and preferably 0.2 μm or more and 1.0 μm or less.

[0147] The thickness of the first thermal transfer layer 50 can be adjusted, for example, by the coating amount of the first thermal transfer layer 50. For example, the coating amount of the first thermal transfer layer 50 is 0.1 g / m2 in terms of the amount of solids per unit area. 2 or more, preferably 0.5 g / m 2 For example, the coating amount of the first thermal transfer layer 50 is 3.0 g / m2 in terms of the amount of solid content per unit area. 2 and preferably 2.5 g / m 2 For example, the coating amount of the first thermal transfer layer 50 is 0.1 g / m2 in terms of the amount of solids per unit area. 2 More than 3.0g / m 2 or less, preferably 0.5 g / m 2 More than 2.5g / m 2 The specific thickness of the first thermal transfer layer 50 (before printing) may be, for example, 0.05 μm or more and 3.0 μm or less, and preferably 0.5 μm or more and 2.5 μm or less.

[0148] The thickness of the intermediate layer 51 can be adjusted, for example, by the coating amount of the intermediate layer 51. For example, the coating amount of the intermediate layer 51 is 0.1 g / m2 in terms of the amount of solid content per unit area. 2or more, and preferably 0.2 g / m 2 For example, the coating amount of the intermediate layer 51 is 2.0 g / m2 in terms of the amount of solid content per unit area. 2 and preferably 1.5 g / m 2 For example, the coating amount of the intermediate layer 51 is 0.1 g / m2 in terms of the amount of solid content per unit area. 2 More than 2.0g / m 2 or less, preferably 0.2 g / m 2 More than 1.5g / m 2 The specific thickness of the intermediate layer 51 (before printing) may be, for example, 0.05 μm or more and 2.0 μm or less, and preferably 0.2 μm or more and 1.5 μm or less. The intermediate layer 51 is preferably thinner than the first thermal transfer layer 50 and the second thermal transfer layer 52. This is because if the intermediate layer 51, which does not contain a colorant such as a pigment, is too thick, the film separation may be poor, and the clarity of the recorded pattern may be reduced.

[0149] The thickness of the second thermal transfer layer 52 can be adjusted, for example, by the coating amount of the second thermal transfer layer 52. For example, the coating amount of the second thermal transfer layer 52 is 0.2 g / m2 in terms of the amount of solid content per unit area. 2 or more, and preferably 1.0 g / m 2 For example, the coating amount of the second thermal transfer layer 52 is 7.0 g / m2 in terms of the amount of solid content per unit area. 2 and preferably 5.0 g / m 2 For example, the coating amount of the second thermal transfer layer 52 is 0.2 g / m 2 in terms of the amount of solids per unit area. 2 More than 7.0g / m 2 and preferably 1.0 g / m 2 More than 5.0g / m 2 The specific thickness of the second thermal transfer layer 52 (before printing) may be, for example, 0.05 μm or more and 7.0 μm or less, and preferably 1.0 μm or more and 5.0 μm or less.

[0150] The total thickness of the transferred material is preferably 13.5 μm or less. If the total thickness of the transferred material exceeds 10 μm, the heating temperature of the thermal head 6 must be set high, which may shorten the life of the thermal head 6. Furthermore, if the thickness of the first thermal transfer layer 50 (black in this embodiment) and the thickness of the second thermal transfer layer 52 (red in this embodiment) are extremely different (for example, a thickness difference of four times or more), the influence of red may remain strong even in black printing, and the black color may be inferior. Therefore, it is necessary to adjust the thickness of the first thermal transfer layer 50 and the second thermal transfer layer 52 and the selection of the colorant within an appropriate application amount range.

[0151] [Peeling mode of thermal transfer recording medium 47] 15 to 19 are diagrams showing the state of peeling of thermal transfer recording medium 47. Referring to FIGS. 15 to 19, there are a number of peeling modes for thermal transfer recording medium 47. The peeling modes in FIGS. 15 to 19 may be referred to as first to fifth peeling modes, respectively. From the viewpoint of the energy supplied to thermal head 6, a low-energy peeling mode shown in FIGS. 15 to 18 and a high-energy peeling mode shown in FIG. 19 can be distinguished.

[0152] 15 to 18 show peeling modes when peeling (thermal transfer) is performed in the first state C1 via heating control (low energy application) of the first temperature curve 55 in FIG. 14. In the first peeling mode in FIG. 15, the rupture strength between the intermediate layer 51 and the second thermal transfer layer 52 is the lowest in the thermal transfer recording medium 47 in the first state C1, and peeling occurs at their interface. In the second peeling mode in FIG. 16, the rupture strength in the second thermal transfer layer 52 is the lowest in the thermal transfer recording medium 47 in the first state C1, and peeling occurs inside the second thermal transfer layer 52. In the third peeling mode in FIG. 17, the rupture strength in the intermediate layer 51 is the lowest in the thermal transfer recording medium 47 in the first state C1, and peeling occurs inside the intermediate layer 51. In the fourth peeling mode in FIG. 18, in the first state C1, the layer in contact with the second thermal transfer layer 52 is a mixed layer 61 formed by melting and mixing the components of the first thermal transfer layer 50 and the intermediate layer 51. The breaking strength between the mixed layer 61 and the second thermal transfer layer 52 is the smallest in the thermal transfer recording medium 47, and peeling occurs at the interface between them. The first peeling mode in FIG. 15 and the fourth peeling mode in FIG. 18 are interfacial failures, while the second peeling mode in FIG. 16 and the third peeling mode in FIG. 17 are cohesive failures. In any of the peeling modes in FIGS. 15 to 18, the second thermal transfer layer 52 is transferred to the printer tape 2.

[0153] FIG. 19 shows a peeling mode when peeling (thermal transfer) is performed in the second state C2 via heating control (high energy application) of the second temperature curve 56 in FIG.

[0154] In the fifth peeling mode of FIG. 19, the breaking strength between the base layer 48 and the welding layer 70 in the second state C2 is the smallest in the thermal transfer recording medium 47, and peeling occurs at the interface therebetween (interface fracture).

[0155] In the peeling mode of FIG. 19, the first thermal transfer layer 50 and the second thermal transfer layer 52 in an adhered state are selectively transferred to the printer tape 2.

[0156] 15 to 19, it can be confirmed by, for example, observing a cross section of the thermal transfer recording medium 47 after rupture, based on, for example, an SEM (Scanning Electron Microscope) image, a TEM (Transmission Electron Microscope) image, or the like of the thermal transfer recording medium 47 after rupture.

[0157] As described above, in the first to fourth peeling modes, the characters recorded on the printing surface 31 of the printer tape 2 have the color of the second thermal transfer layer 52, for example, red. In the fifth peeling mode, the characters recorded on the printing surface 31 of the printer tape 2 have the color of the first thermal transfer layer 50, for example, black. [Example]

[0158] The present disclosure will be further explained below based on experimental examples, but the configuration of the present disclosure is not limited to these examples.

[0159] [Coating material for first thermal transfer layer] The components shown in Table 1 below were dissolved in a mixed solvent of toluene and methyl ethyl ketone (MEK) in a mass ratio of 1:4 to prepare a coating material for the first thermal transfer layer with a solids concentration of 22.5 mass%. The ratio of the active ingredient in the acrylic adhesive was 80 mass parts per 100 mass parts of epoxy resin.

[0160] [Table 1]

[0161] The components in the table are as follows:

[0162] Epoxy resin: JER1007 manufactured by Mitsubishi Chemical Corporation [basic solid type, softening point (ring and ball method): 128°C, number average molecular weight Mn: approximately 2900] Acrylic adhesive: AS-665 manufactured by Lion Specialty Chemicals Co., Ltd. [Solid content: 40% by mass] Tackifier: Terpene phenol resin, YS Polyster T80 (softening point: 80±5°C) manufactured by Yasuhara Chemical Co., Ltd. Carbon black: MA100 powder manufactured by Mitsubishi Chemical Corporation (LFF, DBP absorption: 100 cm 3 / 100g [Coating material for welding layer] A polyamide resin (Tomaid 1315 manufactured by T&K TOKA Corporation, softening point: 130±5°C) was dissolved in a mixed solvent of toluene and methyl ethyl ketone (MEK) in a mass ratio of 1:1 to prepare a coating material for the welding layer with a solids concentration of 10% by mass.

[0163] [Coating material for intermediate layer (1)] A thermoplastic elastomer (Tuftec H1521, SEBS, MFR: 12.3 g / 10 min, styrene content 18% by mass, manufactured by Asahi Kasei Corporation) was dissolved in a mixed solvent of toluene and hexane in a mass ratio of 1 / 1 to prepare a coating material (1) for the intermediate layer with a solids concentration of 10% by mass.

[0164] [Coating material for intermediate layer (2)] Intermediate layer coating material (2) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of modified polyolefin resin (Surfren (registered trademark) P-1000 manufactured by Mitsubishi Chemical Corporation) was used instead of the thermoplastic elastomer. The solid content was 10% by mass.

[0165] [Coating material for second thermal transfer layer] Each component shown in Table 2 below was dissolved in a mixed solvent of toluene and MEK in a mass ratio of 1 / 4 to prepare a coating material for the second thermal transfer layer with a solids concentration of 28 mass %.

[0166] [Table 2]

[0167] The components in the table are as follows:

[0168] Epoxy resin: JER1004 manufactured by Mitsubishi Chemical Corporation [basic solid type, softening point (ring and ball method): 97°C, number average molecular weight Mn: approximately 1650] Wax: Toyochem Carnauba Wax No. 2 Powder (Melting Point: 80-86°C) Red pigment: CI Pigment Red 53:1 (SYMULER® Lake Red C-102, manufactured by DIC Corporation) [Experimental Examples 1-6] (1) Manufacturing of thermal transfer recording media First, a PET film having a thickness of 4.5 μm was prepared as a substrate layer. Next, a silicone resin having a solid content per unit area of ​​0.1 g / m was applied to the surface (back side) of the substrate layer opposite to the surface on which the thermal transfer layer was formed. 2 A backside layer of the above was formed. Next, the solid content per unit area of ​​the previously prepared welding layer coating material was adjusted to have the thickness shown in Table 3, and the coating was applied to the surface of the base layer and then dried to form a welding layer. Next, the solid content per unit area of ​​the previously prepared first thermal transfer layer coating material was adjusted to have the thickness shown in Table 3 below, and the coating was applied on the welding layer and then dried to form a first thermal transfer layer. Next, the solid content per unit area of ​​one of the previously prepared intermediate layer coating materials was adjusted to have the thickness shown in Table 3 below, and the coating was applied on the first thermal transfer layer and then dried to form an intermediate layer. Next, the solid content per unit area of ​​the previously prepared second thermal transfer layer coating material was adjusted to have the thickness shown in Table 3 below, and the coating was applied on the intermediate layer and then dried to form a second thermal transfer layer, thereby producing a thermal transfer recording medium. The compositions of each layer of the thermal transfer recording media obtained in Experimental Examples 1 to 6 are as shown in Table 3 below. (2) Evaluation (2-1) Fringe printability evaluation The thermal transfer recording medium produced in each experimental example was slit into ribbons of a specified width, wound into a roll, and set in a thermal transfer printer (a prototype printer manufactured by Brother Industries, Ltd.) The main specifications of the thermal transfer printer were as follows: <Resolution> 300dpi line thermal head <Resistance of heating element> 1830Ω <Transfer load> 30N / 2inch <Transport speed> 20mm / sec <Peeling distance> 110mm Next, in an ambient temperature of 25°C, the energy applied to the thermal head of the thermal transfer printer was set to low energy (0.25 mJ / dot: 25 V (0.34 W / dot) / 750 μsec, red) and a predetermined print pattern was recorded on the surface of a variable information printing label material (polyester film (white, glossy), FR1415-50 manufactured by Lintec Corporation). The print pattern consisted of numerous 5 dot x 5 dot squares arranged at intervals in the form of polka dots. One polka dot from the printed pattern was then magnified and observed under a microscope. The area ratio (black / red + black) of the red printed image and the black printed image (periphery) in the polka dot was determined, and the printability of the fringe was evaluated based on the following criteria. ◯: The area ratio was less than 10%. △: The area ratio was 10% or more and less than 20%. ×: The area ratio was 20% or more. (2-2) Evaluation of recording clarity The thermal transfer recording medium produced in each experimental example was slit into ribbons of a specified width, wound into a roll, and loaded into a thermal transfer printer (a prototype printer manufactured by Brother Industries, Ltd.) with the same specifications as in (2-1). Next, in an environment with an ambient temperature of 25°C, the energy value applied to the thermal head, which was preset in the thermal transfer printer, was set to low energy (0.25 mJ / dot: 25 V (0.34 W / dot) / 750 μsec, red) or high energy (0.34 mJ / dot: 25 V (0.34 W / dot) / 1000 μsec, black), and a barcode was recorded on the surface of a variable information printing label material (polyester film (white, glossy), FR1415-50 manufactured by Lintec Corporation). The recorded barcode was then read using a barcode verifier (Laser Examiner Elite IS manufactured by Munazowo Co., Ltd.), and the decodability grade specified in the American National Standards Institute (ANSI X3.182-1990) was calculated from the results, and the clarity of the recording was evaluated according to the following criteria. ○: The decodability grade for both black and red was A [excellent] or B [good]. △: The decodability grade of either black or red was C [good], and the other was C [good] or better. ×: At least one of the black and red colors had a decodability grade of D (fair) or F (poor).

[0169] The results are shown in Tables 3 and 4. Among Experimental Examples 1 to 6, Experimental Examples 1 to 4 may be examples, and Experimental Examples 5 and 6 may be comparative examples. (2-3) Observation of fracture location The thermal transfer recording media produced in each experimental example were slit into ribbons of the specified width, wound into a roll, and loaded into a thermal transfer printer (a prototype printer manufactured by Brother Industries, Ltd.) with the same specifications as in (2-1). Next, in an ambient temperature of 25°C, the energy applied to the thermal head of the thermal transfer printer was set to either low energy (0.25 mJ / dot: 25 V (0.34 W / dot) / 750 μsec, red) or high energy (0.34 mJ / dot: 25 V (0.34 W / dot) / 1000 μsec, black), and a 70 mm square solid image was recorded on the surface of a variable information printing label material (polyester film (white, glossy), FR1415-50 manufactured by Lintec Corporation). In both cases, the peel distance of the thermal transfer printer was secured at 110 mm, allowing the label to cool sufficiently (to below 60°C) before the peeling process. The cross section of the solid image obtained was observed using a transmission electron microscope (TEM: Hitachi High-Tech HT7820, accelerating voltage 100 kV). The locations of fractures on the thermal transfer recording medium were confirmed for both the black and red transfers. The fracture locations were classified according to the peeling mode as follows:

[0170] First peeling mode: Between the intermediate layer and the second thermal transfer layer (interface failure; see Figure 15) Second peel mode: Inside the second thermal transfer layer (cohesive failure, see Figure 16) Third delamination mode: Inside the interlayer (cohesive failure, see Figure 17) Fourth peeling mode: Between the mixed layer and the second thermal transfer layer (interface failure; see Figure 18) Fifth peeling mode: Between the substrate layer and the welded layer (interface failure; see Figure 19) The results are shown in Tables 3 and 4. In Tables 3 and 4, the first to fifth peeling modes are each indicated by a circled number. In Tables 3 and 4, when multiple peeling modes are shown, this indicates that different peeling modes occurred in the in-plane direction of the thermal transfer recording medium. Furthermore, since Experimental Example 2 had a layer structure without an intermediate layer, strictly speaking, the peeling mode in Experimental Example 2 was the same as that in which the intermediate layer 51 was omitted from Figures 16, 18, and 19.

[0171] [Table 3]

[0172] [Table 4]

[0173] A comparison of Experimental Example 1 with Experimental Examples 5 and 6 revealed that fringe printing properties can be improved by making the second thermal transfer layer thinner than the first thermal transfer layer. In Experimental Examples 5 and 6, the thickness of the second thermal transfer layer was greater than or equal to the thickness of the first thermal transfer layer, which is thought to have made fringes more likely to occur.

[0174] In Experimental Example 2, when no intermediate layer was provided, the first thermal transfer layer and the second thermal transfer layer were in contact with each other and adjacent to each other, which made fringing more likely to occur than in Experimental Example 1. In addition, the first thermal transfer layer and the second thermal transfer layer were difficult to separate, resulting in poor clarity.

[0175] In Experimental Example 3, when the intermediate layer was formed relatively thick, the fringe printability was good. On the other hand, the intermediate layer did not have good sharpness, and the clarity was poor due to excess peeling, etc.

[0176] In Experimental Example 4, if the intermediate layer is made of a material that undergoes cohesive failure, such as polyolefin, the peeling position during low-temperature printing occurs inside the intermediate layer, and the transferred material becomes part of the second thermal transfer layer and the intermediate layer. Even in this case, it was found that fringe printability can be improved if the total thickness of the transferred material is thinner than the first thermal transfer layer before transfer. However, because the intermediate layer undergoes cohesive failure, the clarity is inferior to when a thermoplastic elastomer (SEBS) is used for the intermediate layer. [Explanation of symbols]

[0177] 1:Printing device 2: Printer tape 3: Ink ribbon 20: Heating element 31:Print surface 32: Back side 33: Adhesive surface 34: Back side 35: Base material layer 36: First ink layer 37: Second ink layer 38 :Surface 39: Back side 40: 1st part 41:Second part 42 :1st part 43:Second part 44: Printing pattern 45: Red pattern 46: Black pattern 47: Thermal transfer recording medium 48: Base material layer 49: Back layer 50: 1st thermal transfer layer 51: Middle class 52:Second thermal transfer layer 53 :Surface 54: Back side 80: Fringe 87: First boundary 88: Second boundary 89: Third boundary 96: 1st temperature distribution curve 97:Second temperature distribution curve 98: High temperature side boundary conditions 99: Low temperature side boundary conditions 100: Central Department 101:Zhou Yubu C1: 1st state C2: 2nd state F1: External Force T1: First temperature T2: Second temperature T3: Third temperature T R1 Temperature reached T R2 Temperature reached T b :Temperature reached T0: Weekly temperature Th: Temperature reached T1: temperature rise value Tl: Temperature reached

Claims

1. A thermal transfer recording medium comprising a substrate layer, a first ink layer containing a first ink, and a second ink layer containing a second ink laminated in this order, wherein at least a portion of the first ink layer and the second ink layer is thermally transferred to a print-receiving medium, when an external force is applied to the base layer and the second ink layer in a direction away from each other in a first state in which the thermal transfer recording medium is heated to a temperature equal to or higher than a first temperature and a temperature equal to or lower than a second temperature and then cooled to a temperature equal to or lower than a third temperature, the thermal transfer recording medium is broken between the first ink layer and the second ink layer or within the second ink layer, when the external force is applied in a second state in which the thermal transfer recording medium is heated to a temperature exceeding the second temperature and then cooled to a third temperature or lower, the thermal transfer recording medium is broken between the first ink layer and the base layer or within the first ink layer, a total thickness before thermal transfer of all layers that are broken and separated from the base material layer in the first state is thinner than the first ink layer; The thermal transfer recording medium, wherein the first temperature is higher than the third temperature.

2. when the external force is applied in the first state, the breaking strength between the first ink layer and the second ink layer or within the second ink layer is the smallest among the thermal transfer recording media, 2. The thermal transfer recording medium according to claim 1, wherein when the external force is applied in the second state, the breaking strength between the first ink layer and the base layer or within the first ink layer is the smallest among the thermal transfer recording media.

3. The thermal transfer recording medium according to claim 1 or 2, further comprising an intermediate layer between the first ink layer and the second ink layer.

4. The thermal transfer recording medium according to claim 3 , wherein when the external force is applied in the first state, the recording medium is broken between the intermediate layer and the second ink layer.

5. 5. The thermal transfer recording medium according to claim 4, wherein when the external force is applied in the first state, the breaking strength between the intermediate layer and the second ink layer is the smallest in the thermal transfer recording medium.

6. The thermal transfer recording medium according to claim 3 , wherein the intermediate layer is broken when the external force is applied in the first state.

7. 7. The thermal transfer recording medium according to claim 6, wherein when the external force is applied in the first state, the intermediate layer has the smallest breaking strength of the thermal transfer recording medium.

8. A thermal transfer recording medium as described in claim 3, wherein the intermediate layer is a layer containing a thermoplastic elastomer.

9. the thermal transfer recording medium has a welding layer between the substrate layer and the first ink layer, 3. The thermal transfer recording medium according to claim 1, wherein when the external force is applied in the second state, the recording medium is broken between the welding layer and the base layer.

10. The thermal transfer recording medium according to claim 9 , wherein when the external force is applied in the second state, the breaking strength between the welding layer and the base layer is the smallest among the thermal transfer recording media.

11. A thermal transfer recording medium as described in Claim 9, wherein the welding layer is a layer containing at least one type selected from the group consisting of polyamide-based resins, polyester-based resins, epoxy-based resins, phenol-based resins and polyvinyl alcohol-based resins.

12. A thermal transfer recording medium as described in claim 1 or 2, wherein the thermal transfer recording medium includes an intermediate layer between the first ink layer and the second ink layer, and a welding layer between the substrate layer and the first ink layer.

13. The intermediate layer is a layer containing a thermoplastic elastomer, 13. The thermal transfer recording medium according to claim 12, wherein the welding layer is a layer containing at least one resin selected from the group consisting of polyamide resins, polyester resins, epoxy resins, phenol resins, and polyvinyl alcohol resins.

14. the first state is a state in which the base layer of the thermal transfer recording medium is heated to a temperature equal to or higher than the first temperature and equal to or lower than the second temperature, and then cooled to a temperature equal to or lower than the third temperature; 3. The thermal transfer recording medium according to claim 1, wherein the second state is a state in which the base layer of the thermal transfer recording medium is heated to a temperature exceeding the second temperature and then cooled to a temperature equal to or lower than the third temperature.

15. a heating step of heating a thermal transfer recording medium, in which a base layer, a first ink layer containing the first ink, and a second ink layer containing the second ink are laminated in this order, while the thermal transfer recording medium is in contact with a print-receiving medium; a cooling step of cooling the thermal transfer recording medium heated in the heating step; a transfer step of transferring at least a portion of the first ink and the second ink to the print medium by applying an external force in a direction away from the base layer and the second ink layer of the thermal transfer recording medium cooled by the cooling step, In the heating step and the cooling step, a first portion of the thermal transfer recording medium is heated to a temperature equal to or higher than a first temperature and equal to or lower than a second temperature, and then cooled to a third temperature or lower to form a first state; and a second portion of the thermal transfer recording medium is heated to a temperature higher than the second temperature, and then cooled to a third temperature or lower to form a second state; In the transfer step, By applying the external force, the thermal transfer recording medium is broken between the first ink layer and the second ink layer or within the second ink layer in the first portion of the thermal transfer recording medium, the second ink is transferred to the printing medium, and the total thickness of all the transferred layers before thermal transfer is thinner than the first ink layer; By applying the external force, the thermal transfer recording medium is broken between the first ink layer and the base layer or within the first ink layer in the second portion of the thermal transfer recording medium, and the first ink and the second ink are transferred to the print medium; The printing device, wherein the first temperature is greater than the third temperature.

16. A thermal transfer recording medium according to claim 1 or 2; a cassette containing a print-receiving medium onto which a portion of the thermal transfer recording medium is thermally transferred;

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