Thermal transfer recording medium and printing apparatus

Abstract

To provide a thermal transfer recording medium that can record characters of at least two colors having good sharpness.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 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 intermediate layer 51 contains a thermoplastic elastomer. Thus, 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, it can be broken between the first thermal transfer layer 50 and the base material layer 48, while in a second state where the thermal transfer recording medium 47 is heated to a level higher than the second temperature and then cooled to a level equal to or lower than the third temperature, it can be broken between the first thermal transfer layer 50 and the second thermal transfer layer 52.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This disclosure relates to a thermal transfer recording medium capable of recording characters of different colors, and a printing apparatus for transferring the thermal transfer recording medium onto a printing medium. [Background technology]

[0002] For example, Patent Documents 1 and 2 disclose a thermal transfer recording medium capable of recording characters of different colors (e.g., 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 to the printing medium. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2000-094843 [Patent Document 2] Japanese Patent Application Publication No. 62-227788 [Patent Document 3] Japanese Patent Application Publication No. 63-214481 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] One embodiment of the present disclosure provides a thermal transfer recording medium capable of recording at least two-color characters with good clarity. [Means for solving the problem]

[0005] A thermal transfer recording medium according to one embodiment of the present disclosure includes a substrate layer having a first surface and a second surface, and a first thermal transfer layer, an intermediate layer, and a second thermal transfer layer laminated in direct contact with each other in order on the first surface of the substrate layer, wherein the intermediate layer includes a thermoplastic elastomer. [Effects of the Invention]

[0006] A thermal transfer recording medium according to one embodiment of the present disclosure includes an intermediate layer containing a thermoplastic elastomer, and is capable of recording at least two-color characters with good clarity. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing the structure of a printing apparatus according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a block diagram showing the electrical configuration of the printing apparatus. [Figure 3] Figure 3 is a schematic diagram illustrating the heating and cooling processes of the printing apparatus. [Figure 4] Figures 4A and 4B are schematic diagrams illustrating the cooling process and transfer process of the printing apparatus. [Figure 5] Figures 5A and 5B show examples of print patterns produced by the printing device. [Figure 6] Figure 6 is a schematic cross-sectional view showing the layer structure of an ink ribbon according to one embodiment of the present disclosure. [Figure 7] Figure 7 shows the relationship between the elapsed time and the temperature reached by the thermal transfer recording medium during the heating and cooling processes. [Figure 8] Figure 8 shows the relationship between the elapsed time and the interlayer adhesion force of the thermal transfer recording medium during the heating and cooling processes. [Figure 9] Figure 9 shows the relationship between the elapsed time and the interlayer adhesion force of the thermal transfer recording medium during the heating and cooling processes. [Figure 10] Figure 10 shows the state of peeling of the thermal transfer recording medium. [Figure 11] Figure 11 shows the state of peeling of the thermal transfer recording medium. [Figure 12] Figure 12 shows the state of peeling of the thermal transfer recording medium. [Figure 13] Figure 13 shows the state of peeling of the thermal transfer recording medium. [Figure 14] Figure 14 shows the state of peeling of the thermal transfer recording medium. [Figure 15] Figure 15 shows the state of peeling of the thermal transfer recording medium. [Figure 16] Figure 16 is a diagram for comparing the solubility parameters (SP values) of each constituent material of a thermal transfer recording medium according to one embodiment of the present disclosure. [Figure 17] Figure 17 shows the relationship between the type of material constituting a part of the thermal transfer recording medium and the magnitude of the solubility parameter. [Modes for carrying out 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] Figure 1 is a schematic diagram showing the structure of a printing apparatus 1 according to one embodiment of the present disclosure.

[0010] Referring to Figure 1, the printing device 1 is a thermal transfer type thermal printer that thermally transfers ink from an ink ribbon 3 as characters onto a printer tape 2, which is an example of a printing medium. The printer tape 2 may include, for example, a strip-shaped film tape containing a base material to which the ink is directly transferred, or a paper label tape in which a large number of 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 apparatus 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 for removing the printer tape 2 after printing is formed in the outer wall of the housing 4. A cutter (not shown) may be provided near the outlet 9. By cutting with the cutter, the printer tape 2 can be separated and removed into labels of the size required for each unit of use.

[0014] The tape cassette 5 may be a detachable cartridge attached to the housing 4. The tape cassette 5 may house, in order from upstream to downstream in the tape feeding direction D1 (from right to left in Figure 1), a printer tape roll 10 (which may also be called a label tape roll), a supply roller 11, an ink ribbon roll 12, an ink ribbon release member 13, and an ink ribbon winding 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 are directly attached to the printing device 1, for example.

[0015] The printer tape roll 10 is made by winding the printer tape 2 into a cylindrical shape and is rotatably held in, for example, a tape cassette 5. A tape drive shaft 16 provided in the housing 4 is inserted into the supply roller 11. The rotational force R1 generated by the drive of the tape drive shaft 16 is transmitted to the supply roller 11, causing the 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 winding roll 14. The rotational force R2 generated by driving the ribbon drive shaft 18 is transmitted to the ink ribbon winding roll 14, causing the ink ribbon winding roll 14 to rotate.

[0017] The ink ribbon release member 13 may be a guide member that changes the feeding direction D2 of the ink ribbon 3. The ink ribbon release member 13 may have a shape that can contact the ink ribbon 3 while it is being transported, for example, a roller shape or a blade shape. The ink ribbon 3 is partially heat-pressed onto the printer tape 2 by the thermal head 6 and is transported toward the outlet 9 together with the printer tape 2. The ink ribbon release member 13 contacts the ink ribbon 3 during transport and changes the feeding direction D2 of the ink ribbon 3 at a sharp angle with respect to the feeding direction D1 of the printer tape 2. As a result, the printer tape 2 and the ink ribbon 3 are pulled apart, and the ink ribbon 3 is peeled off from the printer tape 2.

[0018] The thermal head 6 is positioned between the printer tape roll 10 and the ink ribbon roll 12 and the ink ribbon release member 13 in the feeding direction D1 of the printer tape 2. The thermal head 6 includes a substrate 19 and a heating element 20 (for example, a heating resistor, etc.) formed on the substrate 19. The Joule heat generated by energizing the heating element 20 is used for the thermal transfer of the 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. The rotational force R3 generated by the drive of 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 the electrical control of the printing apparatus 1 and is installed inside the housing 4.

[0020] [Electrical configuration of printing device 1] Figure 2 is a block diagram showing the electrical configuration of the printing device 1.

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

[0022] ROM 24 stores various programs for driving the printing device 1 (for example, control programs that execute each process shown in Figures 3 and 4A,B). The CPU 23 controls the printing device 1 overall by executing signal processing according to the programs stored in ROM 24 while utilizing the temporary storage function of RAM 26. Memory 25 may be composed of, for example, a part of the storage area of ​​ROM 24. Memory 25 may have a table pre-stored in it for displaying the remaining amount (consumption) of the ink ribbon 3 on the display unit (not shown) of the housing 4.

[0023] The input / output interface 27 is electrically connected to a first drive circuit 28 and a second drive circuit 29. The first drive circuit 28 controls the energization of the heating element 20 of the thermal head 6. The second drive circuit 29 controls the drive motor 30 that rotates the supply roller 11, the ink ribbon winding roll 14, and the platen roller 7 by outputting drive pulses.

[0024] [Flow of the printing process using printing device 1] Figure 3 is a schematic diagram illustrating the heating and cooling processes of the printing apparatus 1. Figures 4A and 4B are schematic diagrams illustrating the cooling and transfer processes of the printing apparatus 1. Figure 4B is an enlarged view of the main part of the transfer pattern as seen from the direction of arrow 4B in Figure 4A. Figures 5A and 5B show an example of a printed pattern 44 produced by the printing apparatus 1. The printing process by the printing apparatus 1 will be specifically explained with reference to Figures 1, 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 winding roll 14. As a result, as shown in Figures 1 and 3, the printer tape 2 and the ink ribbon 3 are transported downstream in an overlapping state. On the printer tape 2, the side facing the ink ribbon 3 is the printing surface 31 (front), and the opposite side is the back surface 32. On the ink ribbon 3, the side facing the printer tape 2 is the adhesive surface 33 (front), and the opposite side is the back surface 34.

[0026] Referring to Figure 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 the surface 38 of the base layer 35, which is an example of the first surface. The surface opposite the surface 38 of the base layer 35 is the 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 the first ink, and the second ink layer 37 may contain a red colorant as an example of the 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. In the thermal head 6, a heating process is performed as shown in Figure 3. Specifically, by pressing the heating element 20, which is heated by the application of electricity, against the ink ribbon 3, this 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 overall, or it may be controlled to different temperatures in parts. For example, as shown in Figure 3, the first part 40 of the heating element 20 may be controlled to a relatively low first heating temperature, and the second part 41 of the heating element 20 may be controlled to a second heating temperature higher than the first heating temperature. As a result, the ink ribbon 3 may include a first part 42 heated at the first heating temperature and a second part 43 heated at the second heating temperature. In the first part 42 and the second part 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] Referring to Figures 3 and 4A,B, a cooling process is performed in the section between the thermal head 6 and the ink ribbon release member 13. Specifically, the ink ribbon 3, which has been heat-pressed onto the printer tape 2 in the heating process, cools naturally in the section from the thermal head 6 to the ink ribbon release member 13, and its temperature decreases toward the operating environment temperature of the printing device 1.

[0030] Subsequently, as shown in Figures 4A and 4B, the ink ribbon release member 13 selectively changes only the feeding 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 a direction away from each other. This separates the printer tape 2 and the ink ribbon 3, and the ink ribbon 3 is wound onto the ink ribbon winding 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, delamination may occur between the base layer 35 and the laminate including the first ink layer 36 and the second ink layer 37, and the laminate may be transferred. On the other hand, in the second portion 43, delamination may occur between the first ink layer 36 and the second ink layer 37, and the second ink layer 37 may be selectively transferred.

[0031] As a result, a print pattern 44 with different colors (for example, two colors, black and red) is formed on the printer tape 2. The print pattern 44 may have different colors for each independent character, as shown in Figure 5A, for example. In Figure 5A, when viewed from the print 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 surface of the 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 Figure 5B, both the red pattern 45 and the black pattern 46 may be visible for each part of the character in the print pattern 44.

[0032] After the ink ribbon 3 is transferred, the printer tape 2 on which the characters are recorded is removed from the output outlet 9 of the printing device 1.

[0033] [An example of a challenge in two-color printing] In a thermal transfer printer (printing device 1), the ink ribbon 3 is heated by the thermal head 6 according to the pattern of the recorded information, and then the ink ribbon 3 is peeled off from the printer tape 2. As a result, the ink layers 36 and 37 selectively melt or soften according to the heating pattern, peel off from the substrate layer 35, and are transferred to the printing surface 31 of the printer tape 2, and characters are recorded on the printing surface 31. Two-color thermal transfer printing as described above is also disclosed in the aforementioned Patent Documents 1 and 2, but it has the following problems.

[0034] For example, Patent Document 1 discloses a thermal transfer sheet for recording two colors, comprising a substrate and a plurality of thermal transfer ink layers with different hues laminated on the substrate (e.g., a first thermal transfer ink layer and a second thermal transfer ink layer). Both thermal transfer ink layers are formed from thermoplastic resin, wax, or the like.

[0035] In Patent Document 1, for example, when relatively low energy is applied to the thermal head and thermal transfer is performed at a relatively low temperature, the first thermal transfer ink layer softens, reducing its adhesion to the substrate, while the second thermal transfer ink layer softens, creating adhesion to the surface of the object to be transferred. However, both thermal transfer ink layers maintain their adhesion by softening together, resulting in the entire thermal transfer ink layer, that is, the first thermal transfer ink layer and the second thermal transfer ink layer, being thermally transferred integrally to the surface of the object to be transferred. Therefore, the characters recorded on the surface of the object to be transferred will be, for example, the color of the first thermal transfer ink layer located on the outermost layer after transfer, such as black.

[0036] On the other hand, when relatively high energy is applied to the thermal head and thermal transfer is performed at a higher temperature, the first thermal transfer ink layer softens further, increasing its adhesion to the substrate, while the second thermal transfer ink layer softens, creating adhesion to the surface of the object to be transferred. During this thermal transfer, so-called reverse transfer occurs, where the first thermal transfer ink layer remains on the substrate side. Therefore, only the second thermal transfer ink layer is selectively thermally transferred to the surface of the object to be transferred. Consequently, the characters recorded on the surface of the object to be transferred will be the color of the second thermal transfer ink layer, for example, red.

[0037] However, between the transfer temperature range (≒ amount of energy applied to the thermal head, the same applies hereinafter) when both thermal transfer ink layers are thermally transferred together (hereinafter sometimes abbreviated as the "low temperature transfer range") and the transfer temperature range when only the second thermal transfer ink layer is thermally transferred (hereinafter sometimes abbreviated as the "high temperature transfer range"), there may be a transfer temperature range (hereinafter sometimes abbreviated as the "cloudy transfer range") in which a portion of the first thermal transfer ink layer is transferred together with the second thermal transfer ink layer, causing the color of the characters to become muddy.

[0038] Furthermore, in thermal transfer sheets where both thermal transfer ink layers are directly laminated, the cloudy transfer area tends to be wide, while the low-temperature and high-temperature transfer areas tend to be narrow. In addition, continuous thermal transfer printing causes heat to accumulate in the thermal head, and the temperature of the thermal head tends to gradually rise. Therefore, it is particularly difficult to maintain the temperature of the thermal head in the low-temperature transfer range, and the color of the text tends to become cloudy during low-temperature transfer.

[0039] The thermal transfer sheet described in Patent Document 1 may further include a release layer formed between the first thermal transfer ink layer and the second thermal transfer ink layer. The release layer is made of a colorless, transparent wax or the like with low melt viscosity and high fluidity. The release layer melts or softens during thermal transfer, promoting the separation of the two thermal transfer ink layers. This can extend the high-temperature transfer range to the lower temperature side and narrow the cloudy transfer range. However, the low-temperature transfer range, in which both thermal transfer ink layers can be transferred integrally while suppressing the peeling of the release layer, tends to narrow. Also, because wax has low melt viscosity, it is easily affected by the surroundings. In particular, when recording fine images such as barcodes, excess peeling may occur, reducing the clarity of the recording.

[0040] Patent Document 2 discloses an ink ribbon comprising a base and a first ink layer and a second ink layer directly laminated on the base. In Patent Document 2, the ink ribbon is first heated in a low-temperature transfer range, and both ink layers are thermally transferred integrally to the surface of the base. Subsequently, if only the second ink layer is to remain, it is considered that the ink ribbon is heated again when peeled off, and the first ink layer is reverse-transferred to the base side. However, the thermal transfer printing described in Patent Document 2 requires a printer equipped with a special thermal head that can reheat after thermal transfer, which has the problem of low versatility.

[0041] Considering the thermal transfer methods described in Patent Documents 1 and 2, the inventors of the present invention have identified several problems. At least one of these problems (the first problem) is to provide a thermal transfer recording medium (ink ribbon) that can simultaneously record at least two colors of characters with good clarity.

[0042] One of the aforementioned problems (the second problem) is to provide a thermal transfer recording medium (ink ribbon) that can be used with a general-purpose thermal transfer printer that supports two-color recording, and which allows for continuous thermal transfer recording without color blurring and clear separation into two colors.

[0043] One of the aforementioned problems (the third problem) is to provide a thermal transfer recording medium (ink ribbon) that, when used with a general-purpose thermal transfer printer that supports two-color recording, allows for continuous thermal transfer recording without color blurring, clearly separating into two colors, and recording characters with excellent clarity without excessive peeling.

[0044] [Introduction of an intermediate layer 51 containing thermoplastic elastomer] To solve the aforementioned problems, the inventors of this application have considered and implemented the introduction of an intermediate layer containing a thermoplastic elastomer into a thermal transfer recording medium (ink ribbon), which will be described in detail below.

[0045] Figure 6 is a schematic cross-sectional view showing the layer structure of a thermal transfer recording medium 47 according to one embodiment of the present disclosure. Figure 6 shows the thermal transfer recording medium 47 in a state adhered to a printer tape 2 as an example of a printing medium.

[0046] The thermal transfer recording medium 47 may be used as an ink ribbon 3 in the printing apparatus 1 and printing process shown in Figures 1 to 4A and 4B. The thermal transfer recording medium 47 includes a base layer 48, a back layer 49, a first thermal transfer layer 50, an intermediate layer 51, and a second thermal transfer layer 52. The first thermal transfer layer 50, the intermediate layer 51, and the second thermal transfer layer 52 are laminated in this order on the surface 53 of the base layer 48, which is an example of the first surface. The surface opposite the surface 53 of the base layer 48 may be the back surface 54. The back layer 49 is laminated on the back surface 54 of the base layer 48. The first thermal transfer layer 50 and the second thermal transfer layer 52 may be referred to as the first ink layer and the second ink layer, respectively.

[0047] The thermal transfer recording medium 47 of this disclosure is characterized by comprising a base layer 48 and a first thermal transfer layer 50, an intermediate layer 51, and a second thermal transfer layer 52 that are sequentially laminated on the surface 53 of the base layer 48 in direct contact with each other. The intermediate layer 51 contains a thermoplastic elastomer as a binder.

[0048] In the thermal transfer recording medium 47, for example, the amount of energy applied to the thermal head 6 (see Figures 1 and 3) may be set to a low level to perform thermal transfer at a relatively low temperature. In this case, the first thermal transfer layer 50 softens, reducing its adhesion to the substrate layer 48. On the other hand, the second thermal transfer layer 52 softens, creating adhesion to the printing surface 31 of the printer tape 2. Furthermore, the affinity between both thermal transfer layers 50, 52 and the intermediate layer 51 increases, improving the adhesion of both thermal transfer layers 50, 52 to the intermediate layer 51. Moreover, compared to waxes and the like that used to form a release layer, as in Patent Document 1, the intermediate layer 51 containing a thermoplastic elastomer has a relatively high melt viscosity. The intermediate layer 51 maintains its adhesion to the first thermal transfer layer 50 and the second thermal transfer layer 52 due to its rubbery elastic force. As a result, the entire thermal transfer layer, that is, the first thermal transfer layer 50, the intermediate layer 51, and the second thermal transfer layer 52, is thermally transferred integrally to the printing surface 31 of the printer tape 2. The characters recorded on the print surface 31 of the printer tape 2 will be the color of the first thermal transfer layer 50 located on the outermost layer after transfer, for example, black.

[0049] On the other hand, the thermal transfer recording medium 47 may be thermally transferred at a higher temperature by setting a higher energy amount applied to the thermal head 6. In this case, the first thermal transfer layer 50 softens further, increasing its adhesion to the substrate layer 48, and the second thermal transfer layer 52 develops adhesion to the printing surface 31 of the printer tape 2. In addition, the adhesion of the first thermal transfer layer 50 to the intermediate layer 51 increases, exceeding the adhesion between the second thermal transfer layer 52 and the intermediate layer 51. During thermal transfer, reverse transfer occurs, with the first thermal transfer layer 50 and the intermediate layer 51 remaining on the substrate layer 48 side, while only the second thermal transfer layer 52 is thermally transferred to the printing surface 31 of the printer tape 2. 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. As a result, a two-color pattern, for example, black and red, can be recorded using a general-purpose thermal transfer printer that supports two-color recording.

[0050] Furthermore, as described above, the thermoplastic elastomer contained in the intermediate layer 51 has a higher melt viscosity than wax, etc., which allows the low-temperature transfer range in which both heat transfer layers 50 and 52 can be transferred integrally to the high-temperature side, and the cloudy transfer range to be narrowed. Moreover, the properties of the intermediate layer 51 containing the thermoplastic elastomer with high melt viscosity, such as rubber-like elasticity and adhesion, are less temperature-dependent than those of both heat transfer layers 50 and 52 and the release layer. Therefore, even if the temperature of the thermal head 6 gradually rises due to continuous heat transfer recording, it is possible to suppress clouding of the color of the characters.

[0051] Therefore, according to this disclosure, even when performing continuous thermal transfer recording using a general-purpose thermal transfer printer that supports two-color recording, the colors are less likely to become muddy, the two colors are clearly separated, and characters with excellent clarity can be recorded without causing excess peeling.

[0052] The following provides a detailed explanation of the specific composition and physical properties of the base layer 48, back layer 49, first thermal transfer layer 50, intermediate layer 51, and second thermal transfer layer 52 included in the thermal transfer recording medium 47.

[0053] (1) Base material layer 48 Examples of the base layer 48 include resin films such as polysulfone, polystyrene, polyamide, polyimide, polycarbonate, polypropylene, polyester, and triacetate; thin papers such as condenser paper and glassine paper; and cellophane. Of these, polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate are preferred from the viewpoint of mechanical strength, dimensional stability, heat treatment resistance, and cost. The thickness of the base layer 48 can be arbitrarily set according to the specifications of the thermal transfer printer, for example. For example, the thickness of the base layer 48 is 1 μm or more, preferably 2 μm or more. For example, the thickness of the base layer 48 is 10 μm or less, preferably 8 μm or less. For example, the thickness of the base layer 48 is 1 μm or more and 10 μm or less, preferably 2 μm or more and 8 μm or less.

[0054] (2) Back layer 49 The back layer 49 improves the heat resistance, slipperiness, abrasion resistance, etc., of the back surface 54 of the base layer 48 that comes into contact with the thermal head 6. Examples of materials for the back layer 49 include silicone resin, fluororesin, silicone-fluoropolymer resin, nitrocellulose resin, silicone-modified urethane resin, and silicone-modified acrylic resin. The back layer 49 may contain a lubricant as needed.

[0055] The back layer 49 can be formed, for example, by applying a coating material obtained by dissolving or dispersing the above-mentioned resin or the like in any solvent to the back surface 54 of the base layer 48, and then drying it. The thickness of the back layer 49 can be set arbitrarily, for example, according to the specifications of the thermal transfer printer. The thickness of the back layer 49 can be adjusted by the amount of back layer 49 applied.

[0056] For example, the coating amount of the back layer 49 is 0.05 g / m², expressed as the amount of solids per unit area. 2 The above is preferable, and preferably 0.1 g / m 2 That concludes the explanation. For example, the coating amount of the back layer 49 is 0.5 g / m², expressed as the amount of solids per unit area. 2 The following, preferably 0.4 g / m 2The following applies: For example, the coating amount of the back layer 49 is 0.05 g / m², expressed as the amount of solids per unit area. 2 More than 0.5g / m 2 The following, preferably 0.1 g / m 2 More than 0.4g / m 2 The following applies: The specific thickness of the back layer 49 is, for example, 0.05 μm or more, preferably 0.1 μm or more. The thickness of the back layer 49 is, for example, 0.5 μm or less, preferably 0.4 μm or less. The thickness of the back layer 49 may be, for example, 0.05 μm or more and 0.5 μm or less, preferably 0.1 μm or more and 0.4 μm or less.

[0057] (3) First thermal transfer layer 50 The first thermal transfer layer 50 can be formed from, for example, any thermoplastic resin. It is preferable to use an epoxy resin as the thermoplastic resin for the first thermal transfer layer 50, considering improvements in affinity and adhesion to the base layer 48 and the intermediate layer 51. Epoxy resins exhibit excellent affinity and adhesion to thermoplastic elastomers that form the base layer 48 and the intermediate layer 51, which are made of polyester films such as PET. The first thermal transfer layer 50 can be formed using an epoxy resin as the thermoplastic resin, without any curing agent added (or removed).

[0058] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, alicyclic epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol AD ​​type epoxy resin, aliphatic epoxy resins such as propylene glycol glycoxy 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, spiroring-containing epoxy resins, epoxy-modified resins, and brominated epoxy resins. Specific examples of epoxy resins are not particularly limited, but examples include the following various epoxy resins. These epoxy resins can be used individually or in combination of two or more types.

[0059] 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: 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): 78°C, number average molecular weight Mn: about 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℃].

[0060] The softening point of the epoxy resin used in the first heat transfer layer 50 is, for example, 95°C or higher, preferably 110°C or higher, and more preferably 125°C or higher. If the softening point is within this range, it is possible to suppress the occurrence of high adhesion between the first heat transfer layer 50 and the substrate layer 48 at relatively low temperatures during low-temperature transfer. Since the low-temperature transfer range of the first heat transfer layer 50 can be sufficiently extended to the high-temperature side, it is possible to suppress color blurring even when heat transfer recording is performed continuously.

[0061] 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 substrate layer 48 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.

[0062] Considering the affinity and compatibility with epoxy resin, as well as the affinity and adhesion to the substrate layer 48 and the intermediate layer 51, an acrylic adhesive is preferred as the adhesive. Specific examples of acrylic adhesives are not particularly limited, but include the following various acrylic adhesives. These acrylic adhesives can be used individually or in combination of two or more.

[0063] Among the Olivine® BPS (solvent-based) series manufactured by Toyo Chem 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) BPS6153K (non-volatile content: 45.5% 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).

[0064] Among the solvent-based adhesives (removable type) manufactured by Lion Specialty Chemicals Co., Ltd., the following are included: AS-325 (solid content concentration: 45% by mass), AS-375 (solid content concentration: 45% by mass), AS-409 (solid content concentration: 45% by mass), AS-417 (solid content concentration: 45% by mass), AS-425 (solid content concentration: 45% by mass), AS-455 (solid content concentration: 45% by mass), AS-665 (solid content concentration: 40% by mass), AS-1107 (solid content concentration: 43% by mass), and AS-4005 (solid content concentration: 45% by mass).

[0065] 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 can improve the sharpness of the first thermal transfer layer 50, suppress excess peeling, and improve the clarity of the characters to be recorded. Examples of tackifiers include ester gum, terpene phenol resin, rosin ester, etc. There are no particular limitations on specific examples of tackifiers, but examples include the following various tackifiers. These tackifiers can be used alone or in combination of two or more.

[0066] Among the terpene phenol resins of the YS Polystar series manufactured by Yasuhara Chemical Co., Ltd., U130 (softening point: 130±5℃), U115 (softening point: 115±5℃), T160 (softening point: 160±5℃), T145 (softening point: 145±5℃), T130 (softening point: 130±5℃), 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℃).

[0067] 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].

[0068] Among the rosin esters in the Pencel (registered trademark) series manufactured by Arakawa Chemical Industries, Ltd., GA-100 [softening point (ring-ball method): 100~110℃], AZ [softening point (ring-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].

[0069] The softening point of the tackifier used in the first thermal transfer layer 50 is, for example, 60°C or higher, preferably 120°C or lower. If the softening point is within this range, the first thermal transfer layer 50 and the intermediate layer 51 can be favorably reverse-transferred to the substrate layer 48 side during high-temperature transfer. Since the high-temperature transfer range of the first thermal transfer layer 50 can be sufficiently expanded to the low-temperature side, it is possible to suppress the turbidity of the color tone.

[0070] The first thermal transfer layer 50 may contain an arbitrary colorant. As the colorant, one or more various colorants corresponding to the color tone of the first thermal transfer layer 50 can be used. The colorant may be, for example, a pigment. Considering the improvement of the weather resistance of the characters, etc., a pigment is preferable as the colorant used in the first thermal transfer layer 50. For example, carbon black is preferable as the pigment for coloring the first thermal transfer layer 50 black. Specific examples of carbon black are not particularly limited, but for example, the following various carbon blacks can be mentioned. These carbon blacks can be used alone or in combination of two or more.

[0071] MA77 powder manufactured by Mitsubishi Chemical Corporation [LFF, DBP absorption: 68 cm 3 / 100 g], MA7 powder [LFF, DBP absorption: 66 cm 3 / 100 g], MA7 granule [LFF, DBP absorption: 65 cm 3 / 100 g], MA8 powder [LFF, DBP absorption: 57 cm 3 / 100 g], MA8 granule [LFF, DBP absorption: 51 cm 3 / 100 g], MA11 powder [LFF, DBP absorption: 64 cm 3 / 100 g], MA100 powder [LFF, DBP absorption: 100 cm 3 / 100 g], MA100 granule [LFF, DBP absorption: 95 cm 3 / 100 g], MA100R powder [LFF, DBP absorption: 100 cm 3 / 100 g], MA100R granule [LFF, DBP absorption: 95 cm 3 / 100g], MA100S powder [LFF, DBP absorption amount: 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]

[0072] Mitsubishi Chemical Corporation's #3030B (furnace method, DBP absorption: 130cm³) 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).

[0073] Among the Toka Black (registered trademark) series manufactured by Tokai Carbon Co., Ltd., #5500 (furnace method, DBP absorption: 155cm 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).

[0074] Among the PRINTEX (registered trademark) series manufactured by Orion Engineered Carbons, L (furnace method, DBP absorption capacity: 120cm) 3 ( / 100g), L6 (furnace method, DBP absorption: 126cm) 3 (100g).

[0075] Among the CONDUCTEX (registered trademark) series manufactured by Birla Carbon, the 975 (furnace method, 170cm) 3 ( / 100g), SC (furnace method, 115cm) 3 (100g).

[0076] Among the VULCAN (registered trademark) series manufactured by CABOT, the XC72 (furnace method, DBP absorption: 174 cm³) 3 ( / 100g), 9A32 (furnace method, DBP absorption: 114cm) 3 ( / 100g), of the company's BLACK PEARLS series, 3700 (furnace method, DBP absorption: 111cm 3 (100g).

[0077] Among the Denka Black (registered trademark) series manufactured by Denka Co., Ltd., Denka Black granular product (acetylene method, DBP absorption: 160 cm³) 3 ( / 100g), FX-35 (acetylene method, DBP absorption: 220cm) 3 ( / 100g), HS-100 (acetylene method, DBP absorption: 140cm) 3 (100g).

[0078] Among the KETJENBLACK (registered trademark) series manufactured by Lion Specialty Chemicals Co., Ltd., EC300J (gasification method, DBP absorption: 360 cm³) 3 ( / 100g), EC600DJ (gasification method, DBP absorption: 495cm³) 3 (100g).

[0079] The proportions of each component in the first thermal transfer layer 50 are not particularly limited. The proportion of acrylic adhesive to 100 parts by mass of epoxy resin is, for example, 30 parts by mass or more, preferably 40 parts by mass or more. The proportion of acrylic adhesive to 100 parts by mass of epoxy resin is, for example, 150 parts by mass or less, preferably 100 parts by mass or less. The proportion of acrylic adhesive to 100 parts by mass of epoxy resin is, for example, 30 parts by mass or more and 150 parts by mass or less, preferably 40 parts by mass or more and 100 parts by mass or less.

[0080] The ratio of tackifier to 100 parts by mass of epoxy resin is, for example, 3 parts by mass or more, preferably 5 parts by mass or more. The ratio of tackifier to 100 parts by mass of epoxy resin is, for example, 150 parts by mass or less, preferably 100 parts by mass or less. The ratio of tackifier to 100 parts by mass of epoxy resin is, for example, 3 parts by mass or more and 150 parts by mass or less, preferably 5 parts by mass or more and 100 parts by mass or less.

[0081] The ratio of a coloring agent such as carbon black to 100 parts by mass of epoxy resin is, for example, 100 parts by mass or more, preferably 130 parts by mass or more. The ratio of a coloring agent to 100 parts by mass of epoxy resin is, for example, 230 parts by mass or less, preferably 200 parts by mass or less. The ratio of a coloring agent to 100 parts by mass of 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.

[0082] Furthermore, for components of the first thermal transfer layer 50 that are supplied in liquid form dissolved or dispersed in any solvent, the amount of each component should be adjusted so that the proportion of the active ingredient falls within the above range (the same applies hereinafter).

[0083] The first thermal transfer layer 50 can be formed, for example, by dissolving or dispersing each of the above components in any solvent, applying a coating material directly onto the surface 53 of the base layer 48, or via any release layer, and then drying it. In this disclosure, the characters to be recorded on the printer tape 2 are color-coded, as shown in Figures 5A and 5B. For this color coding, considering the adjustment of the adhesion between the first thermal transfer layer 50 and the base layer 48 and each of the other layers, it is preferable that the first thermal transfer layer 50 be formed directly on the surface 53 of the base layer 48 without a release layer.

[0084] The thickness of the first thermal transfer layer 50 can be arbitrarily set according to, for example, the specifications of the thermal transfer printer. The thickness of the first thermal transfer layer 50 can be adjusted by the amount of the first thermal transfer layer 50 applied.

[0085] For example, the amount of the first thermal transfer layer 50 applied is 0.1 g / m², expressed as the amount of solids per unit area. 2 The above is preferable, and preferably 0.5 g / m 2 That concludes the explanation. For example, the amount of the first thermal transfer layer 50 applied is 3.0 g / m², expressed as the amount of solids per unit area. 2 The following, preferably 2.5 g / m² 2 The following applies: For example, the amount of the first thermal transfer layer 50 applied is 0.1 g / m², expressed as the amount of solids per unit area. 2 More than 3.0g / m 2 The following, preferably 0.5 g / m 2 More than 2.5g / m 2 The following applies:

[0086] The specific thickness of the first thermal transfer layer 50 (before printing) is, for example, 0.05 μm or more, preferably 0.5 μm or more. The thickness of the first thermal transfer layer 50 is, for example, 3.0 μm or less, preferably 2.5 μm or less. The thickness of the first thermal transfer layer 50 may also be, for example, 0.05 μm or more and 3.0 μm or less, preferably 0.5 μm or more and 2.5 μm or less. The thickness of the first thermal transfer layer 50 can be confirmed, for example, based on SEM (Scanning Electron Microscope) images, TEM (Transmission Electron Microscope) images, etc. of the thermal transfer recording medium 47.

[0087] (4) Middle layer 51 The intermediate layer 51 contains a thermoplastic elastomer as described above. In particular, it is preferable that the intermediate layer 51 be formed solely of 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 ester-based thermoplastic elastomer.

[0088] 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), and styrene-isoprene-styrene block copolymer (SIS). Examples of acetate ester-based thermoplastic elastomers include ethylene-vinyl acetate copolymer (EVA).

[0089] The styrene content in the thermoplastic elastomer contained in the intermediate layer 51 is, for example, 10% by mass or more and 70% by mass or less, preferably 15% by mass or more and 50% by mass or less. If the styrene content is too high, the rubbery elasticity of the intermediate layer 51 decreases, and during low-temperature transfer, it may not be possible to maintain adhesion to the first heat transfer layer 50 and the second heat transfer layer 52, or the color of the characters may become cloudy. If the styrene content is too low, the rubbery elasticity of the intermediate layer 51 becomes too high, and during high-temperature transfer, it may not be possible to peel off the second heat transfer layer 52, causing the color of the characters to become cloudy.

[0090] The thermoplastic elastomer contained in the intermediate layer 51 has a melt mass flow rate (hereinafter sometimes simply abbreviated as "MFR") of, for example, 1000 g / 10 min or less, preferably 400 g / 10 min or less. The MFR may be, for example, the MFR at a temperature of 190°C and a load of 2.16 kg, as determined by the measurement method specified in ISO 1133-1:2011. In the following, unless otherwise specified, the measurement conditions for the MFR are a temperature of 190°C and a load of 2.16 kg.

[0091] Thermoplastic elastomers with an MFR exceeding 400 g / 10 min tend to have too strong an affinity for the second heat transfer layer 52. As a result, the second heat transfer layer 52 may not peel off during high-temperature transfer, causing the color of the characters to become muddy. In addition, the entire heat transfer recording medium 47, i.e., the base layer 48, the first heat transfer layer 50, the intermediate layer 51, and the second heat transfer layer 52, may adhere to the printing surface 31 of the printer tape 2. Thermoplastic elastomers with an MFR exceeding 400 g / 10 min have low melt viscosity and high fluidity, so during low-temperature transfer, they may not be able to maintain adhesion to the first heat transfer layer 50 and the second heat transfer layer 52, or the color of the characters may become muddy.

[0092] In contrast, if the thermoplastic elastomer has an MFR of 400 g / 10 min or less, it is possible to suppress the problems that may occur when using thermoplastic elastomers with an MFR exceeding 400 g / 10 min. Furthermore, even when thermal transfer recording is performed continuously, the colors on the printed surface 31 of the printer tape 2 do not easily become muddy, and the two colors are clearly separated, and it is possible to record characters with excellent clarity without excessive peeling. To further improve these effects, it is preferable that the MFR of the thermoplastic elastomer be 2.5 g / 10 min or less, and especially 2.3 g / 10 min or less, even within the above range.

[0093] There are no particular restrictions on the lower limit of MFR, and thermoplastic elastomers that show "No Flow" in the measurement results at the aforementioned temperature of 190°C and load of 2.16 kg can be used. Specific examples of thermoplastic elastomers are not particularly limited, but include the following types of thermoplastic elastomers. These thermoplastic elastomers can be used individually or in combination of two or more types.

[0094] Among the SEBS products in the ToughTec (registered trademark) series manufactured by Asahi Kasei Corporation, the following are included: H1521 [MFR: 2.3g / 10min], H1051 [MFR: less than 0.8g / 10min], H1052 [MFR: less than 13.0g / 10min], H1272 [MFR: No Flow], P1083 [MFR: 3.0g / 10min], P1500 [MFR: 4.0g / 10min], P5051 [MFR: 3.0g / 10min], and P2000 [MFR: 3.0g / 10min].

[0095] Among the SBS products in the Toughprene® series manufactured by Asahi Kasei Corporation, A [MFR: 2.6g / 10min], 125 [MFR: 4.5g / 10min], and 126S [MFR: 4.5g / 10min].

[0096] Among the Asaprene® T series SBS 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].

[0097] The following are SEPS models from Kuraray Co., Ltd.'s Septon® series: 2002 [MFR: 70g / 10min], 2004F [MFR: 5g / 10min], 2005 [MFR: No Flow], 2006 [MFR: No Flow], 2063 [MFR: 7g / 10min], and 2104 [MFR: 0.4g / 10min]. The MFR measurement conditions for all of these SEPS models were 230°C and 2.16kg load.

[0098] The following are SEEPS devices from the Septon® series manufactured by Kuraray Co., Ltd.: 4033 [MFR: <0.1g / 10min], 4044 [MFR: No Flow], 4055 [MFR: No Flow], 4077 [MFR: No Flow], and 4099 [MFR: No Flow]. The MFR measurement conditions for all of these SEEPS devices were 230°C and 2.16kg load.

[0099] Among the vinyl SIS products in the Hybler (registered trademark) series manufactured by Kuraray Co., Ltd., 5125 [MFR: 4g / 10min] and 5127 [MFR: 5 / 10min].

[0100] Among the EVA products of the UltraSen (registered trademark) series manufactured by Tosoh Corporation, the following are included: 514R [MFR: 0.41g / 10min], 515 [MFR: 2.5g / 10min], 510 [MFR: 2.5g / 10min], 510F [MFR: 2.5g / 10min], 520F [MFR: 2.0g / 10min], 540 [MFR: 3.0g / 10min], 540F [MFR: 3.0g / 10min]. 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〕.

[0101] The intermediate layer 51 can be formed, for example, by dissolving or dispersing a forming material for the intermediate layer 51, which includes at least a thermoplastic elastomer, in any solvent, onto the first heat transfer layer 50, and then drying it.

[0102] The thickness of the intermediate layer 51 can be arbitrarily set according to, for example, the specifications of the thermal transfer printer. The thickness of the intermediate layer 51 can be adjusted by the amount of intermediate layer 51 applied. For example, the amount of intermediate layer 51 applied can be expressed as 0.1 g / m² in terms of solid content per unit area. 2The above is preferable, and preferably 0.2 g / m 2 That concludes the explanation. For example, the amount of intermediate layer 51 applied is 2.0 g / m², expressed as the amount of solids per unit area. 2 The following, preferably 1.5 g / m² 2 The following applies: For example, the amount of intermediate layer 51 applied is 0.1 g / m², expressed as the amount of solids per unit area. 2 More than 2.0g / m 2 The following, preferably 0.2 g / m² 2 More than 1.5g / m 2 The following applies:

[0103] The specific thickness of the intermediate layer 51 (before printing) is, for example, 0.05 μm or more, preferably 0.2 μm or more. The thickness of the intermediate layer 51 is, for example, 2.0 μm or less, preferably 1.5 μm or less. The thickness of the intermediate layer 51 may also be, for example, 0.05 μm or more and 2.0 μm or less, preferably 0.2 μm or more and 1.5 μm or less. The thickness of the intermediate layer 51 can be confirmed, for example, based on SEM (Scanning Electron Microscope) images, TEM (Transmission Electron Microscope) images, etc. of the thermal transfer recording medium 47.

[0104] Due to limitations in coating precision, the thickness of the intermediate layer 51 may vary depending on the measurement location. The coating amount and thickness of the intermediate layer 51 mentioned above may include this error. For example, 0.2 g / m 2 The intermediate layer 51 formed with this coating amount has a measurement of 0.1 g / m² depending on the measurement location. 2 It may have a region having a thickness when formed by the amount of coating applied.

[0105] (5) Second thermal transfer layer 52 The second heat transfer layer 52 can be formed from, for example, any thermoplastic resin. Examples of thermoplastic resins used for the second heat transfer layer 52 include epoxy resin, polyester resin, and polyolefin resin. The thermoplastic resin can be appropriately selected depending on the material used to form the printer tape 2. If the first heat transfer layer 50 is formed from epoxy resin, it is preferable that the second heat transfer layer 52 is also formed from epoxy resin.

[0106] By forming the second heat transfer layer 52 with epoxy resin, the adhesion force of the first heat transfer layer 50 to the substrate layer 48 and the intermediate layer 51 can be counteracted by the adhesion force of the second heat transfer layer 52 to the printer tape 2. This allows for good separation of the first heat transfer layer 50 and the intermediate layer 51 towards the substrate layer 48 and the second heat transfer layer 52 towards the printer tape 2 during high-temperature transfer. Since the high-temperature transfer range can be extended to the low-temperature side, the effect of suppressing color turbidity can be further improved. Examples of epoxy resins include the various epoxy resins exemplified as the epoxy resin for the first heat transfer layer 50. These epoxy resins can be used individually or in combination of two or more types.

[0107] The second thermal transfer layer 52 may contain wax in addition to the thermoplastic resin. The inclusion of wax allows for good separation of the first thermal transfer layer 50 and the intermediate layer 51 to the substrate layer 48 side and the second thermal transfer layer 52 to the printer tape 2 side during high-temperature transfer. As a result, the high-temperature transfer range can be extended to the low-temperature side, further improving the effect of suppressing color blurring.

[0108] As the wax, any wax having affinity and compatibility with thermoplastic resins such as epoxy resins can be used. For example, natural waxes such as carnauba wax, paraffin wax, and microcrystalline wax, and synthetic waxes such as Fischer-Tropsch wax can be used. There are no particular limitations on specific examples of waxes, but for example, carnauba wax No. 1 flakes, No. 2 flakes, No. 3 flakes, No. 1 powder, and No. 2 powder (all with a melting point of 80-86°C) manufactured by Toyo Chem Co., Ltd., and paraffin waxes EMUSTAR-1155 (melting point: 69°C), EMUSTAR-0135 (melting point: 60°C), and EMUSTAR-0136 (manufactured by Nippon Seiro Co., Ltd.) can be used. Examples 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 (setting point: 90°C), SX80 (setting point: 83°C), FT-0165 (melting point: 73°C), and FT-0070 (melting point: 72°C). These waxes can be used individually or in combination of two or more types.

[0109] The second heat transfer layer 52 may contain any coloring agent. As the coloring agent, one or more different coloring agents can be used, depending on the color of the second heat transfer layer 52. For example, the coloring agent may be a pigment. Considering the improvement of the weather resistance of the characters, a pigment is preferred as the coloring agent used in the second heat transfer layer 52. For example, the following various red pigments can be used to color the second heat transfer layer 52 red. These red pigments can be used individually or in combination of two or more.

[0110] 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.

[0111] The proportions of each component in the second thermal transfer layer 52 are not particularly limited. The proportion of wax to 100 parts by mass of epoxy resin is, for example, 3 parts by mass or more, preferably 5 parts by mass or more. The proportion of wax to 100 parts by mass of epoxy resin is, for example, 11 parts by mass or less, preferably 9 parts by mass or less. The proportion 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, preferably 5 parts by mass or more and 9 parts by mass or less.

[0112] The ratio of a coloring agent such as a red pigment to 100 parts by mass of epoxy resin is, for example, 70 parts by mass or more, preferably 80 parts by mass or more. The ratio of a coloring agent such as a red pigment to 100 parts by mass of epoxy resin is, for example, 140 parts by mass or less, preferably 120 parts by mass or less. The ratio of a coloring agent such as a red pigment to 100 parts by mass of epoxy resin is, for example, 70 parts by mass or more and 140 parts by mass or less, preferably 80 parts by mass or more and 120 parts by mass or less.

[0113] The second thermal transfer layer 52 can be formed, for example, by applying a coating material obtained by dissolving or dispersing each of the above components in any solvent onto the intermediate layer 51 and then drying it.

[0114] The thickness of the second thermal transfer layer 52 can be arbitrarily set according to, for example, the specifications of the thermal transfer printer. The thickness of the second thermal transfer layer 52 can be adjusted by the amount of the second thermal transfer layer 52 applied. For example, the amount of the second thermal transfer layer 52 applied is 0.2 g / m², expressed as the amount of solids per unit area. 2 The above is preferable, preferably 1.0 g / m 2 That concludes the explanation. For example, the amount of coating of the second thermal transfer layer 52 is 7.0 g / m², expressed as the amount of solids per unit area. 2 The following, preferably 5.0 g / m² 2 The following applies: For example, the amount of the second thermal transfer layer 52 applied is 0.2 g / m², expressed as the amount of solids per unit area. 2 More than 7.0g / m 2 The following, preferably 1.0 g / m² 2 More than 5.0g / m 2 The following applies:

[0115] The specific thickness of the second thermal transfer layer 52 (before printing) is, for example, 0.05 μm or more, preferably 1.0 μm or more. The thickness of the second thermal transfer layer 52 is, for example, 7.0 μm or less, preferably 5.0 μm or less. The thickness of the second thermal transfer layer 52 may also be, for example, 0.05 μm or more and 7.0 μm or less, preferably 1.0 μm or more and 5.0 μm or less. The thickness of the second thermal transfer layer 52 can be confirmed, for example, based on SEM (Scanning Electron Microscope) images, TEM (Transmission Electron Microscope) images, etc. of the thermal transfer recording medium 47.

[0116] [Introduction of an intermediate layer 51 based on irreversible changes in force] Figure 6 shows a thermal transfer recording medium (ink ribbon) 47 comprising an intermediate layer 51 containing a thermoplastic elastomer, as an example of a thermal transfer recording medium capable of simultaneously recording at least two colors of characters with good clarity. The inventors of the present invention have also investigated and implemented a thermal transfer recording medium that exhibits similar effects from a different perspective, which will be described in detail below. In short, while Figure 6 focused on the chemical composition of the intermediate layer 51, the following focuses on the irreversible change in interlayer adhesion strength due to temperature control of the thermal transfer recording medium 47.

[0117] Figure 7 shows the relationship between the elapsed time and the temperature reached by the thermal transfer recording medium 47 during the heating and cooling processes shown in Figures 1 to 4A and 4B.

[0118] The horizontal axis in Figure 7 shows the elapsed time of the printing process of the printing apparatus 1. t0 indicates the start of printing, t1 indicates the end of heating by the thermal head 6, and t2 indicates the arrival of the ink ribbon to the release member 13. The vertical axis in Figure 7 shows 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. These external factors may include, for example, heating by the thermal head 6 and natural cooling of the thermal transfer recording medium 47 during transport.

[0119] Referring to Figure 7, in the printing apparatus 1, the temperature reached by the thermal transfer recording medium 47 can be controlled by controlling the temperature output (thermal energy) of the thermal head 6 with the control circuit 22. For example, a relatively low first energy amount is applied to the thermal head 6 during the heating process. In this case, the temperature of the thermal transfer recording medium 47 is as shown by the dashed-dotted first temperature curve 55, relative to the ambient temperature (e.g., room temperature) T surrounding the thermal transfer recording medium 47. E From T, it increases exponentially. R1 It reaches.

[0120] Achieved temperature T R1 The temperature may be defined as a temperature between a first temperature T1 and a second temperature T2. For example, the first temperature T1 is 60°C to 120°C, preferably 70°C to 90°C. For example, the second temperature T2 is 80°C to 180°C, preferably 130°C to 150°C. The target temperature T R1 This can be set appropriately according to the output setting method of the thermal head 6 of the printing device 1 being used. For example, the target temperature may be set in relation to quantitative parameters such as the voltage, current, and energizing time supplied to the heating element 20 of the thermal head 6. Alternatively, the target temperature may be set in relation to a relative value with respect to a predetermined reference value (for example, the value before energizing is set to 0 (zero)).

[0121] On the other hand, in the heating process, 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 solid second temperature curve 56, relative to the ambient temperature T E From T, it increases exponentially. R2 Reaching temperature T. R2 This can also be defined as a temperature exceeding the second temperature T2.

[0122] After the heating process, the thermal transfer recording medium 47 is naturally cooled in the section up to the ink ribbon release member 13 (see also Figures 3 and 4A,B). During the cooling process, the temperature of the thermal transfer recording medium 47 reaches the target temperature T. R1 and T R2 From T, it decreases exponentially. PIt reaches this point. The temperature reached at this time is T P This is the temperature at which a portion of the thermal transfer recording medium 47 is peeled off by the ink ribbon peeling member 13, therefore peeling temperature T P It may also be defined as follows: Peeling temperature T P Preferably, the third temperature T3 is lower than or equal to the first temperature T1. The third temperature T3 is lower than the first temperature T1 (i.e., the first temperature T1 is higher than or equal to the third temperature T3), for example, 40°C to 90°C, and preferably 60°C to 80°C. The values ​​of the first temperature T1, the second temperature T2, and the third temperature T3 can be appropriately set within the temperature range necessary for transfer to the printer tape 2, taking into consideration the chemical composition and physical properties of the ink of the thermal transfer recording medium 47.

[0123] The temperature curve (cooling curve) of the thermal transfer recording medium 47 during the cooling process will eventually converge to a constant temperature, regardless of which heating control is used in the heating process, as shown by the first temperature curve 55 and the second temperature curve 56. Therefore, by ensuring a longer cooling process time (t1→t2), the peeling temperature T of the first temperature curve 55 and the second temperature curve 56 can be controlled. P These can be made almost the same. To lengthen the cooling process time, for example, the distance between the thermal head 6 and the ink ribbon release member 13 (release distance L1 in Figure 1) can be increased. For example, the state of the thermal transfer recording medium 47 after the heating and cooling processes have been performed according to the temperature change shown by the first temperature curve 55 in Figure 7 may be defined as the first state C1. In contrast, the state of the thermal transfer recording medium 47 after the heating and cooling processes have been performed according to the temperature change shown by the second temperature curve 56 in Figure 7 may be defined as the second state C2.

[0124] Thus, in the printing apparatus 1, the temperature output (temperature energy) of the thermal head 6 is controlled, and the process from the start of the heating process to the end of the cooling process is controlled, starting temperature (ambient temperature T E ) and final temperature (peel temperature T PWhile keeping the temperature constant, the temperature reached by the thermal transfer recording medium 47 can be varied in various ways. Taking this temperature control into consideration, for example, by controlling the temperature output of the thermal head 6 according to the physical properties of the substrate layer 48, back layer 49, first thermal transfer layer 50, intermediate layer 51, and second thermal transfer layer 52 of the thermal transfer recording medium 47 shown in Figure 6, it is expected that the adhesive force between each layer of the thermal transfer recording medium 47 can be controlled.

[0125] Figures 8 and 9 show the relationship between elapsed time and interlayer adhesion of the thermal transfer recording medium 47 during the heating and cooling processes. Figure 8 shows the change in each adhesion force F when the temperature of the thermal transfer recording medium 47 is changed according to the first temperature curve 55 in Figure 6. Figure 9 shows the change in each adhesion force F when the temperature of the thermal transfer recording medium 47 is changed according to the second temperature curve 56 in Figure 6.

[0126] The horizontal axes in Figures 8 and 9 show the elapsed time of the printing process of the printing apparatus 1. t0 indicates the start of printing, t1 indicates the end of heating by the thermal head 6, and t2 indicates the time when the ink ribbon reaches the release member 13. The vertical axes in Figures 8 and 9 show the magnitude of the adhesive force between each layer of the thermal transfer recording medium 47.

[0127] In Figures 8 and 9, the first adhesive force F1 between the substrate layer 48 and the first thermal transfer layer 50 of the thermal transfer recording medium 47 is shown by the solid first adhesive force curve 57. The second adhesive force F2 between the first thermal transfer layer 50 and the second thermal transfer layer 52 is shown by the dashed-dotted second adhesive force curve 58. The first adhesive force F1 may include the force at which the bond between the substrate layer 48 and the first thermal transfer layer 50 breaks, and the force at which the first thermal transfer layer 50 breaks internally. The second adhesive force F2 may include the force at which the bond between the intermediate layer 51 and the second thermal transfer layer 52 breaks, and the force at which the intermediate layer 51 breaks internally. Furthermore, if the components of the first thermal transfer layer 50 and the intermediate layer 51 are mixed by melting to form a mixed layer, the second adhesive force F2 may also include the force at which the bond between the mixed layer and the second thermal transfer layer 52 breaks.

[0128] Referring to Figures 8 and 9, both the first adhesive force F1 and the second adhesive force F2 change over time as the heating and cooling processes are performed, regardless of the amount of energy applied to the thermal head 6 during the heating process. More specifically, both the first adhesive force F1 and the second adhesive force F2 decrease as the heating time progresses, and both the first adhesive force F1 and the second adhesive force F2 increase as the cooling time after heating progresses.

[0129] The relative magnitudes of the first adhesive force F1 and the second adhesive force F2 before heating and after cooling change depending on the amount of energy applied to the thermal head 6. For example, as shown in Figure 8, when the amount of energy applied to the thermal head 6 is relatively low, the second adhesive force F2 is greater than the first adhesive force F1 both before heating and after cooling (first state C1). Therefore, if peeling is performed in the first state C1, since the first adhesive force F1 < second adhesive force F2, peeling occurs between the substrate layer 48 and the first thermal transfer layer 50, and the first thermal transfer layer 50 and the second thermal transfer layer 52 in an adhered state are transferred to the printer tape 2. On the other hand, in order to create the condition where the first adhesive force F1 < second adhesive force F2 after cooling, it is preferable to perform the cooling process for at least longer than the time t3 corresponding to the intersection point 59 of the first adhesive force curve 57 and the second adhesive force curve 58 shown in Figure 9. This is because the thermal transfer recording medium 47 is sufficiently cooled, and cold peeling can be reliably performed.

[0130] Furthermore, as shown in Figure 9, for example, if the amount of energy applied to the thermal head 6 is relatively high, the relative magnitudes of the first adhesive force F1 and the second adhesive force F2 are reversed before heating and after cooling (second state C2). Before heating, the second adhesive force F2 is greater than the first adhesive force F1, while after cooling (second state C2), the second adhesive force F2 is less than the first adhesive force F1. In other words, the first adhesive force F1 undergoes an irreversible change. Therefore, if peeling is performed in second state C2, since the first adhesive force F1 > second adhesive force F2, peeling occurs between the first thermal transfer layer 50 and the second thermal transfer layer 52, and the second thermal transfer layer 52 is transferred to the printer tape 2. On the other hand, in order to create the condition where the first adhesive force F1 > second adhesive force F2 after cooling, it is preferable to perform the cooling process for at least longer than the time t3 corresponding to the intersection point 60 of the first adhesive force curve 57 and the second adhesive force curve 58 shown in Figure 9. This is because the thermal transfer recording medium 47 is sufficiently cooled, allowing for reliable cold peeling.

[0131] Time t3 should be appropriately set such that the first adhesive strength F1 < second adhesive strength F2 after cooling of the thermal transfer recording medium 47 heated with low energy, and the first adhesive strength F1 > second adhesive strength F2 after cooling of the thermal transfer recording medium 47 heated with high energy. For example, it may be the time required to lower the temperature reached by the thermal transfer recording medium 47 to a third temperature T3, in both the low-energy and high-energy application cases. The peeling distance L1 (see Figure 1) required to secure this time t3 is, for example, 70 mm to 150 mm, preferably 90 mm to 120 mm.

[0132] Thus, by utilizing the irreversible change in the first adhesive force F1 that occurs in accordance with the amount of energy applied to the thermal head 6, the peeling position of the thermal transfer recording medium 47 can be freely controlled, and a thermal transfer recording medium 47 that can simultaneously record at least two colors of characters with good clarity can be provided.

[0133] (1) Peeling mode of thermal transfer recording medium 47 Figures 10 to 15 show the peeling state of the thermal transfer recording medium 47. First, how the thermal transfer recording medium 47 peels depending on the relative magnitudes of the first adhesive force F1 and the second adhesive force F2 will be explained with reference to Figures 10 to 15. Referring to Figures 10 to 15, there are several peeling modes for the thermal transfer recording medium 47. The peeling modes in Figures 10 to 15 may be referred to as the first to sixth peeling modes, respectively. From the viewpoint of the energy supplied to the thermal head 6, they can be distinguished into the low-energy peeling mode shown in Figures 10 and 11 and the high-energy peeling mode shown in Figures 12 to 15.

[0134] Figures 10 and 11 show the delamination modes when delamination (thermal transfer) is performed in the first state C1 via heating control (low energy application) of the first temperature curve 55 in Figure 7. In the first delamination mode in Figure 10, the breaking strength (first adhesive force F1) between the substrate layer 48 and the first thermal transfer layer 50 becomes the lowest in the thermal transfer recording medium 47 in the first state C1, and delamination occurs at these interfaces. In the second delamination mode in Figure 11, the breaking strength (first adhesive force F1) within the first thermal transfer layer 50 becomes the lowest in the thermal transfer recording medium 47 in the first state C1, and delamination occurs inside the first thermal transfer layer 50. The first delamination mode in Figure 10 is interfacial fracture, and the second delamination mode in Figure 11 is cohesive fracture. In either delamination mode in Figures 10 or 11, the first thermal transfer layer 50 and the second thermal transfer layer 52 in an adhered state are transferred to the printer tape 2.

[0135] Figures 12 to 15 show the delamination modes when delamination (thermal transfer) is performed in the second state C2 via heating control (high energy application) as shown in the second temperature curve 56 of Figure 7. The delamination modes in Figures 12 to 15, like the first and second delamination modes, can be distinguished into at least two types: interfacial fracture and cohesive fracture.

[0136] In the third delamination mode shown in Figure 12, in the second state C2, the tensile strength (second adhesive strength F2) between the first thermal transfer layer 50 and the second thermal transfer layer 52 becomes the lowest within the thermal transfer recording medium 47, and delamination occurs at their interface (interface fracture). In the fourth delamination mode shown in Figure 13, in the second state C2, the tensile strength (second adhesive strength F2) within the second thermal transfer layer 52 becomes the lowest within the thermal transfer recording medium 47, and delamination occurs inside the second thermal transfer layer 52 (cohesive fracture).

[0137] In the fifth delamination mode shown in Figure 14, in the second state C2, the tensile strength (second adhesive strength F2) within the intermediate layer 51 becomes the lowest in the thermal transfer recording medium 47, and delamination occurs inside the intermediate layer 51 (cohesive failure). In the sixth delamination mode shown in Figure 15, in the second state C2, the layer in contact with the second thermal transfer layer 52 is a mixed layer 61 formed by the melting and mixing of the components of the first thermal transfer layer 50 and the intermediate layer 51. The tensile strength (second adhesive strength F2) between the mixed layer 61 and the second thermal transfer layer 52 becomes the lowest in the thermal transfer recording medium 47, and delamination occurs at their interface (interfacial failure).

[0138] In any of the peeling modes shown in Figures 12 to 15, the second thermal transfer layer 52 is selectively transferred to the printer tape 2 so that the first thermal transfer layer 50 does not remain.

[0139] Whether the thermal transfer recording medium 47 fractured in any of the delamination modes shown in Figures 10 to 15 can be confirmed, for example, by observing the cross-section of the thermal transfer recording medium 47 after fracture. For example, this can be confirmed based on SEM (Scanning Electron Microscope) images, TEM (Transmission Electron Microscope) images, etc., of the thermal transfer recording medium 47 after fracture.

[0140] As described above, in the first to second peel modes, the characters recorded on the printed surface 31 of the printer tape 2 will be the color of the first thermal transfer layer 50, for example, black. In the third to sixth peel modes, the characters recorded on the printed surface 31 of the printer tape 2 will be the color of the second thermal transfer layer 52, for example, red.

[0141] Therefore, in order to provide a thermal transfer recording medium 47 that can simultaneously record characters of at least two colors with good clarity, at least one of the first to second peeling modes must be achieved when heating control (low energy application) of the first temperature curve 55, and at least one of the third to sixth peeling modes must be achieved when heating control (high energy application) of the second temperature curve 56. To achieve these, the conditions of each layer of the thermal transfer recording medium 47 were examined from the following multiple viewpoints.

[0142] (2) Chemical composition of each layer of the thermal transfer recording medium 47 In terms of the chemical composition of each layer of the thermal transfer recording medium 47, the chemical compositions of the base layer 48, back layer 49, first thermal transfer layer 50, intermediate layer 51, and second thermal transfer layer 52, as described in the section "[Introduction of an intermediate layer 51 containing a thermoplastic elastomer]" above, are preferred. Of course, since the thermal transfer recording medium 47 having this chemical composition includes an intermediate layer 51 containing a thermoplastic elastomer, it is possible to simultaneously record at least two colors of characters with good clarity using temperature control conditions typical of general-purpose thermal transfer printers, regardless of the temperature control shown in Figure 7.

[0143] When thermal transfer in the printing apparatus 1 is performed with the temperature control shown in Figure 7, other compositions can be used as the intermediate layer 51 in addition to the thermoplastic elastomer described above. For example, the intermediate layer 51 may contain at least one of a polyolefin resin and a long-chain alkyl resin. These resins have relatively low polarity. Therefore, when peeling (thermal transfer) is performed in the second state C2 via the heating control (high energy application) of the second temperature curve 56 in Figure 7, cohesive failure can be caused inside the intermediate layer 51. This allows for good peeling between the first thermal transfer layer 50 and the second thermal transfer layer 52.

[0144] Examples of polyolefin resins include Surflen® P-1000 manufactured by Mitsubishi Chemical Corporation.

[0145] Examples of long-chain alkyl resins include 1010, 1010S, 1050, 1070, and 406 from the P-ROIL® series manufactured by Lion Specialty Chemicals Co., Ltd.

[0146] By providing an intermediate layer 51 containing the resin exemplified above, a thermal transfer recording medium 47 capable of simultaneously recording at least two colors of characters with good clarity can be provided.

[0147] (3) Solubility parameters (SP values) of each layer of the thermal transfer recording medium 47 From the perspective of the physical properties of each layer of the thermal transfer recording medium 47, we focus on the relative relationship of the solubility parameters (SP values) of the constituent components of each layer. By adjusting the SP values ​​of the constituent components of each layer, the interlayer adhesion and internal delamination of the thermal transfer recording medium 47 can be controlled. The closer the SP values ​​of constituent components in contact with each other, the easier they are to adhere (high affinity), and the further apart the SP values ​​are, the easier they are to delaminate (low affinity). Therefore, by adjusting the balance of the SP values ​​and content of the constituent components of each layer of the thermal transfer recording medium 47, the delamination position in the thermal transfer recording medium 47 can be flexibly controlled. This provides a thermal transfer recording medium 47 that can simultaneously record at least two colors of characters with good clarity.

[0148] In the following, when showing the relative relationship (magnitude) of SP values, it is sufficient that the calculation conditions for the SP values ​​being compared are the same. For example, the SP value may be an HSP value (Hansen solubility parameter) or an SP value (Hildebrand solubility parameter). Furthermore, the method for calculating the SP value is not particularly limited. For example, it may be a method derived from the latent heat of vaporization, a method using the Hildebrand Rule, a method estimating from physical properties such as surface tension, or a method estimating from molecular structure such as Small's calculation method, Fedors' calculation method, Hansen's calculation method, or Hoy's calculation method. In this disclosure, when showing the range and specific numerical values ​​of SP values, the SP value refers to the SP value (Hildebrand solubility parameter) unless otherwise specified.

[0149] Figure 16 is a diagram for comparing the solubility parameters (SP values) of each constituent material of a thermal transfer recording medium 47 according to one embodiment of the present disclosure.

[0150] Referring to Figure 16, the first thermal transfer layer 50 is composed of at least a first material 62 and a second material 63. The first material 62 is a material having a relatively lower SP value compared to the second material 63. The SP value of the first material 62 is, for example, 7.5 to 9.5, preferably 8.0 to 9.0. Examples of the first material 62 include adhesives and tackifiers, etc., as exemplified as components of the first thermal transfer layer 50 in the aforementioned "[Introduction of an intermediate layer 51 containing a thermoplastic elastomer]".

[0151] The second material 63 is a material having a relatively higher SP value compared to the first material 62. The SP value of the second material 63 is, for example, 9.0 to 12.0, preferably 10.0 to 11.0. Examples of the second material 63 include thermoplastic resins, as exemplified as components of the first heat transfer layer 50 in the aforementioned "[Introduction of an intermediate layer 51 containing a thermoplastic elastomer]".

[0152] The weight ratio of the first material 62 and the second material 63 in the first thermal transfer layer 50 is, for example, 30 parts by mass or more, preferably 45 parts by mass or more, of the first material 62 per 100 parts by mass of the second material 63. For example, 300 parts by mass or less, preferably 200 parts by mass or less, of the first material 62 per 100 parts by mass of the second material 63. For example, 30 parts by mass or more and 300 parts by mass or less, preferably 45 parts by mass or more and 200 parts by mass or less, of the first material 62 per 100 parts by mass of the second material 63.

[0153] The intermediate layer 51 is composed of at least a third material 64. The third material 64 is a material having a relatively lower SP value compared to the second material 63 and the fifth material 66 (described later). The SP value of the third material 64 is, for example, 7.5 to 10.0, preferably 8.0 to 9.0. Examples of the third material 64 include the thermoplastic elastomer exemplified in the above-mentioned "[Introduction of Intermediate Layer 51 Including Thermoplastic Elastomer]", as well as polyolefin resins and long-chain alkyl resins.

[0154] The second heat transfer layer 52 is composed of at least a fourth material 65 and a fifth material 66. The fourth material 65 is a material having a relatively higher SP value compared to the fifth material 66. The SP value of the fourth material 65 is, for example, 9.0 to 12.0, preferably 10.0 to 11.0. Examples of the fourth material 65 include thermoplastic resins, etc., as exemplified as components of the second heat transfer layer 52 in the aforementioned "[Introduction of an intermediate layer 51 containing a thermoplastic elastomer]".

[0155] The fifth material 66 is a material having a relatively lower SP value compared to the fourth material 65. The SP value of the fifth material 66 is, for example, 7.5 to 9.5, preferably 8.0 to 9.0. Examples of the fifth material 66 include wax, as exemplified as a component of the second heat transfer layer 52 in the aforementioned "[Introduction of an intermediate layer 51 containing a thermoplastic elastomer]".

[0156] The weight ratio of the fourth material 65 and the fifth material 66 in the second thermal transfer layer 52 is, for example, 3 parts by mass or more, preferably 5 parts by mass or more, of the fifth material 66 per 100 parts by mass of the fourth material 65. For example, 11 parts by mass or less, preferably 9 parts by mass or less, of the fifth material 66 per 100 parts by mass of the fourth material 65. For example, 3 parts by mass or more and 11 parts by mass or less, preferably 5 parts by mass or more and 9 parts by mass or less, of the fifth material 66 per 100 parts by mass of the fourth material 65.

[0157] Figure 17 shows the relationship between the type of material that constitutes part of the thermal transfer recording medium 47 and the magnitude of the solubility parameter.

[0158] As mentioned above, examples of materials that can be used as the first to fifth materials 62 to 66 have been provided, but the materials used are not particularly limited as long as the relative relationship (magnitude relationship) of the SP values ​​in the thermal transfer recording medium 47 is as described above. For example, materials can be selected as appropriate by referring to the magnitude relationship shown in Figure 17. In doing so, it should be considered that materials with similar SP values ​​tend to adhere more easily, while those with farther SP values ​​tend to peel off more easily.

[0159] For example, with respect to the first heat transfer layer 50, a terpene phenol resin may be selected as the first material 62 and an epoxy resin as the second material 63. For example, with respect to the intermediate layer 51, a thermoplastic elastomer, polyolefin, etc. may be selected as the third material 64. For example, with respect to the second heat transfer layer 52, a wax may be selected as the fourth material 65 and an epoxy resin as the fifth material 66.

[0160] As described above, by combining the SP values ​​in the manner described, at least one of the first to second peeling modes can be achieved during heating control (low energy application) of the first temperature curve 55 in Figure 7, and at least one of the third to sixth peeling modes can be achieved during heating control (high energy application) of the second temperature curve 56. As a result, a thermal transfer recording medium 47 capable of simultaneously recording at least two colors of characters with good clarity can be provided. [Examples]

[0161] 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.

[0162] [Coating material for first thermal transfer layer (I)] Each component shown in Table 1 below was dissolved in a mixed solvent of toluene and methyl ethyl ketone (MEK) in a mass ratio of 1 / 4 to prepare a coating material (I) for the first thermal transfer layer with a solid content concentration of 22.5% by mass. The proportion of the active ingredient in the acrylic adhesive was 80 parts by mass per 100 parts by mass of epoxy resin.

[0163] [Table 1]

[0164] The components listed in the table are as follows:

[0165] Epoxy resin: JER1007 manufactured by Mitsubishi Chemical Corporation [Basic solid type, softening point (ring-sphere method): 128°C, number-average molecular weight Mn: approx. 2900, SP value: 9.5~11.5] Acrylic adhesive: AS-665 manufactured by Lion Specialty Chemicals Co., Ltd. [Solid content concentration: 40% by mass, SP value: 8.0~9.0] Tackifier: Terpene phenol resin, YS Polystar T80 manufactured by Yasuhara Chemical Co., Ltd. (softening point: 80±5℃, SP value: 8.0~9.5) Carbon black: MA100 powder manufactured by Mitsubishi Chemical Corporation [LFF, DBP absorption capacity: 100cm] 3 / 100g] [Coating material for first thermal transfer layer (II)] The first thermal transfer layer coating material (II) was prepared in the same manner as the first thermal transfer layer coating material (I), except that the same amount of JER1004 [basic solid type, softening point (ring-sphere method): 97°C, number average molecular weight Mn: approximately 1650, SP value: 9.5~11.5] manufactured by Mitsubishi Chemical Corporation was added as the epoxy resin. The solid content concentration was 22.5% by mass, and the proportion of the active ingredient in the acrylic adhesive was 80 parts by mass per 100 parts by mass of epoxy resin.

[0166] [Coating material for first thermal transfer layer (III)] The first thermal transfer layer coating material (III) was prepared in the same manner as the first thermal transfer layer coating material (I), except that no tackifier was added and the amount of acrylic adhesive was 271 parts by mass. The solid content concentration was 22.5% by mass, and the proportion of active ingredients in the acrylic adhesive was 108.4 parts by mass per 100 parts by mass of epoxy resin.

[0167] [Coating material for intermediate layer (1)] A thermoplastic elastomer [ToughTec H1521, SEBS, MFR: 12.3 g / 10 min, styrene content 18% by mass, SP value: 7.5-9.0, manufactured by Asahi Kasei Corporation] was dissolved in a mixed solvent of toluene and hexane in a 1:1 mass ratio to prepare an intermediate layer coating material (1) with a solid content concentration of 10% by mass.

[0168] [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 Asahi Kasei Corporation's ToughTec H1517 [SEBS, MFR: less than 3.0 g / 10 min, styrene content 43% by mass, SP value: 7.5~9.0] was added as a thermoplastic elastomer. The solid content concentration was 10% by mass.

[0169] [Coating material for intermediate layer (3)] Intermediate layer coating material (3) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of ToughTec H1272 [SEBS, MFR: No Flow, styrene content 35% by mass, SP value: 7.5~9.0] manufactured by Asahi Kasei Corporation was added as a thermoplastic elastomer. The solid content concentration was 10% by mass.

[0170] [Coating material for intermediate layer (4)] Intermediate layer coating material (4) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of Asahi Kasei Corporation's ToughTec H1221 [SEBS, MFR: less than 4.5 g / 10 min, styrene content 12% by mass, SP value: 7.5~9.0] was added as a thermoplastic elastomer. The solid content concentration was 10% by mass.

[0171] [Coating material for intermediate layer (5)] Intermediate layer coating material (5) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of ToughTec H1043 [SEBS, MFR: less than 2.0 g / 10 min, styrene content 67% by mass, SP value: 7.5~9.0] manufactured by Asahi Kasei Corporation was added as a thermoplastic elastomer. The solid content concentration was 10% by mass.

[0172] [Coating material for intermediate layer (6)] Intermediate layer coating material (6) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of Toughprene A [SBS, MFR: 2.6 g / 10 min, styrene content 40% by mass, SP value: 7.5~9.0] manufactured by Asahi Kasei Corporation was added as a thermoplastic elastomer. The solid content concentration was 10% by mass.

[0173] [Coating material for intermediate layer (7)] Intermediate layer coating material (7) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of UltraSen 634 [EVA, MFR: 4.3 g / 10 min, SP value: 7.5~9.0] manufactured by Tosoh Corporation was added as a thermoplastic elastomer. The solid content concentration was 10% by mass.

[0174] [Coating material for intermediate layer (8)] Intermediate layer coating material (8) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of UltraSen 722 [EVA, MFR: 400g / 10min, SP value: 7.5~9.0] manufactured by Tosoh Corporation was added as a thermoplastic elastomer. The solid content concentration was 10% by mass.

[0175] [Coating material for intermediate layer (9)] Intermediate layer coating material (9) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of UltraSen 725 [EVA, MFR: 1000g / 10min, SP value: 7.5~9.0] manufactured by Tosoh Corporation was added as a thermoplastic elastomer. The solid content concentration was 10% by mass.

[0176] [Coating material for intermediate layer (10)] Intermediate layer coating material (10) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of UltraSen 684 [EVA, MFR: 2000g / 10min, SP value: 7.5~9.0] manufactured by Tosoh Corporation was added as a thermoplastic elastomer. The solid content concentration was 10% by mass.

[0177] [Coating material for intermediate layer (11)] Intermediate layer coating material (11) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of amorphous polyester resin [Byron® 200, manufactured by Toyobo Co., Ltd., SP value: 9.5-11.0], which is a thermoplastic resin, was added instead of thermoplastic elastomer. The solid content concentration was 10% by mass.

[0178] [Coating material for intermediate layer (12)] Intermediate layer coating material (12) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of wax [carnauba wax No. 2 flakes manufactured by Toyo Chem Co., Ltd. (melting point: 80-86°C, SP value: 7.0-9.0)] was added instead of thermoplastic elastomer. The solid content concentration was 10% by mass.

[0179] [Coating material for intermediate layer (13)] Intermediate layer coating material (13) was prepared in the same manner as intermediate layer coating material (1), except that the same amount of modified polyolefin resin [Surflen® P-1000, manufactured by Mitsubishi Chemical Corporation, SP value: 7.5-8.5] was added instead of thermoplastic elastomer. The solid content concentration was 10% by mass.

[0180] Table 2 below summarizes the material names, MFRs, and styrene content of the intermediate layer coating materials (1) to (13). The mixing ratio of the constituent components is omitted as the solids / toluene / hexane ratio is 10 / 45 / 45 for all of the intermediate layer coating materials (1) to (13).

[0181] [Table 2]

[0182] [Coating material for second thermal transfer layer (I)] Each component shown in Table 3 below was dissolved in a mixed solvent of toluene and MEK in a mass ratio of 1 / 4 to prepare a coating material (I) for the second thermal transfer layer with a solid content concentration of 28% by mass.

[0183] [Table 3]

[0184] Each component in the table is as follows.

[0185] Epoxy resin: JER1004 manufactured by Mitsubishi Chemical Corporation [basic solid type, softening point (ring and ball method): 97 °C, number average molecular weight Mn: about 1650, SP value: 9.5 - 11.5] Wax: Carnauba wax No. 2 powder manufactured by Toyochem Co., Ltd. (melting point: 80 - 86 °C, SP value: 7.0 - 9.0) Red pigment: C.I. Pigment Red 53:1 [SYMULER (registered trademark) Lake Red C-102 manufactured by DIC Corporation] [Experimental Examples 1 - 15] (1) Manufacture of thermal transfer recording medium First, a PET film with a thickness of 4.5 μm was prepared as the base layer. Next, on the surface of the base layer opposite to the surface where the thermal transfer layer is formed (the back surface), a back surface layer made of a silicone resin with a solid content per unit area of 0.1 g / m 2 was formed. Next, any of the previously prepared first thermal transfer layer coating materials was applied to the surface of the base layer and then dried to form a first thermal transfer layer with a solid content per unit area of 1.5 g / m 2 Next, any of the previously prepared intermediate layer coating materials was applied onto the first thermal transfer layer and then dried to form an intermediate layer with a solid content per unit area of 1 g / m 2 Next, the previously prepared second thermal transfer layer coating material (I) was applied onto the intermediate layer and then dried to form a second thermal transfer layer with a solid content per unit area of 2.5 g / m 2 to manufacture a thermal transfer recording medium. The composition of each layer of the thermal transfer recording media obtained in Experimental Examples 1 - 15 is as shown in Tables 4 - 6 below. In the table, NF in the binder column of the intermediate layer indicates No Flow. (2) Evaluation (2 - 1) Continuous recording property evaluation The thermal transfer recording media produced in each experiment were slit into ribbons of a predetermined width, wound into rolls, and set in a thermal transfer printer (Zebra 110Xi4 printer manufactured by Zebra Co., Ltd.). Next, under ambient temperature of 25°C, the energy value applied to the thermal head, which was pre-set in the thermal transfer printer, was set to 16 (low temperature, black) or 24 (high temperature, red), and a solid 70mm square image was continuously recorded 20 times on the surface of a variable information printing label material (polyester film (white, glossy), FR1415-50 manufactured by Lintec Corporation) at a printing speed of 5 inches / sec. If slight clouding was observed during recording, continuous printing was stopped at that point, and the number of times black or red was printed was recorded as the number of continuous prints. For evaluation, experiments in which black was printed even after 20 attempts were considered to have excellent continuous printability of 20 or more attempts, while experiments in which clouding occurred after 3 attempts or less were considered not practically sufficient. The results are shown in Tables 4-6. (2-2) Evaluation of the clarity of the record The thermal transfer recording media produced in each experimental example were slit into ribbons of a predetermined width, wound into rolls, and set in a thermal transfer printer (Zebra 110Xi4 printer manufactured by Zebra Co., Ltd.). Next, under ambient temperature of 25°C, the energy value applied to the thermal head, which was pre-set in the thermal transfer printer, was set to 16 (low temperature, black) or 24 (high temperature, red), and barcodes were recorded on the surface of a variable information printing label material (polyester film (white, glossy), FR1415-50 manufactured by Lintec Corporation) at a printing speed of 5 inches / sec. The recorded barcodes were then read using a barcode verification machine (Laser Examiner Elite IS manufactured by Munazo Co., Ltd.), and the decodeability grade specified in the American National Standards Institute standard ANSI X3.182-1990) was determined, and the clarity of the recording was evaluated according to the following criteria. ○: Both the black and red versions had a decoderability rating of A [Excellent] or B [Superior]. △: Either the black or red component had a decoderability rating of C [Good], and the other component had a rating of C [Good] or higher. ×: At least one of the black or red colors had a decoderability rating of D [OK] or F [NG].

[0186] The results are shown in Tables 4-6. Note that among Experimental Examples 1-15, Experimental Examples 1-12 may be the examples and Experimental Examples 13-15 may be the comparative examples.

[0187] [Table 4]

[0188] [Table 5]

[0189] [Table 6]

[0190] From a comparison of Experimental Examples 1-12 and 13-15 in Tables 4-6, it was found that by providing an intermediate layer made of thermoplastic elastomer between the first and second thermal transfer layers, a thermal transfer recording medium can be obtained that allows for continuous thermal transfer recording without color blurring, clear separation into two colors, and recording of characters with excellent clarity without excessive peeling.

[0191] Furthermore, from the results of Experimental Examples 1 to 12, it was found that EVA, SBS, SEBS, etc., are preferred as thermoplastic elastomers for forming the intermediate layer. Moreover, considering further improvement of continuous recording performance, it was found that thermoplastic elastomers with an MFR of 1000 g / 10 min or less at a temperature of 190°C and a load of 2.16 kg are preferred, more preferably 400 g / 10 min or less, particularly preferably 2.5 g / 10 min or less, and most preferably 2.3 g / 10 min or less.

[0192] From a comparison between Experimental Example 1 and Experimental Example 11, it was found that the epoxy resin used to form the first heat transfer layer has a softening point of 95°C or higher, is more preferably 110°C or higher, and is particularly preferably 125°C or higher. Furthermore, from a comparison between Experimental Example 1 and Experimental Example 12, it was found that it is preferable to incorporate a tackifier together with an acrylic adhesive in the epoxy resin used to form the first heat transfer layer.

[0193] [Experimental Examples 16-33] (1) Manufacturing of thermal transfer recording media First, a PET film with a thickness of 4.5 μm was prepared as the base layer. Next, on the side of the base layer opposite to the surface where the heat transfer layer is formed (the back side), a silicone-based resin with a solid content of 0.1 g / m² per unit area was applied. 2 A back layer was formed. Next, one of the first heat transfer coating materials prepared earlier was applied to the surface of the substrate layer and then dried until the solid content per unit area was 1.7 g / m². 2 A first heat transfer layer was formed. Next, one of the previously prepared intermediate layer coating materials was applied to the first heat transfer layer and then dried to form an intermediate layer. Regarding the amount of intermediate layer coating material applied, in experimental examples 16 to 29, the solid content per unit area was 1 g / m². 2 The results for experimental examples 30-33 were as shown in Table 10 below. Next, the second heat transfer layer coating material (I) prepared earlier was applied to the intermediate layer and then dried, resulting in a solid content of 2.5 g / m² per unit area. 2 A second thermal transfer layer was formed to manufacture a thermal transfer recording medium. The composition of each layer of the thermal transfer recording medium obtained in Experimental Examples 16-33 is shown in Tables 7-10 below. In the table, NF in the column for the intermediate layer binder indicates No Flow. (2) Evaluation (2-1) Evaluation of continuous recording ability The thermal transfer recording media produced in each experimental example were slit into ribbons of a predetermined width, wound into rolls, and set in a thermal transfer printer (a prototype printer manufactured by Brother Industries, Ltd.). The main specifications of the thermal transfer printer are as follows. <Resolution> 300dpi line thermal head <Resistance of heating element> 1830Ω <Transfer load> 30N / 2inch <Conveying speed> 20 mm / sec <Peeling distance> 110mm Next, under ambient temperature conditions of 25°C, the energy value applied to the thermal head of the thermal transfer printer was set to either low energy (0.25mJ / dot: 25V (0.34W / dot) / 750μsec, black) or high energy (0.34mJ / dot: 25V (0.34W / dot) / 1000μsec, red). A solid 70mm square image was then continuously recorded 20 times on the surface of a variable information printing label material [polyester film (white, glossy), FR1415-50 manufactured by Lintec Corporation]. If slight turbidity was observed during recording, continuous printing was stopped at that point, and the number of times black or red was printed was recorded as the number of continuous prints. For evaluation, experimental cases in which black was printed even after 20 attempts were considered to have excellent continuous printability of 20 or more attempts, while experimental cases in which turbidity occurred after 3 attempts or less were considered to be not practically sufficient. The results are shown in Tables 7-10. (2-2) Evaluation of the clarity of the record The thermal transfer recording media produced in each experimental example were slit into ribbons of a predetermined width, wound into rolls, and set in a thermal transfer printer with the same specifications as (2-1) [a prototype printer manufactured by Brother Industries, Ltd.]. Next, under ambient temperature of 25°C, the energy value applied to the thermal head, which was pre-set in the thermal transfer printer, was set to either low energy (0.25 mJ / dot: 25 V (0.34 W / dot) / 750 μsec, black) or high energy (0.34 mJ / dot: 25 V (0.34 W / dot) / 1000 μsec, red), and a barcode was recorded on the surface of a label material for variable information printing [polyester film (white, glossy), FR1415-50 manufactured by Lintec Corporation]. The recorded barcodes were then read using a barcode verification machine (Laser Examiner Elite IS manufactured by Munazo Co., Ltd.), and the decodeability grade specified in the American National Standards Institute (ANSI) X3.182-1990) was determined. The clarity of the recording was then evaluated according to the following criteria. 〇: For both black and red, the decoder ability grade was A [excellent] or B [superior]. △: For either black or red, one had a decoder ability grade of C [good], and the other was C [good] or above. ×: For at least one of black or red, the decoder ability grade was D [passable] or F [unusable].

[0194] The results are shown in Tables 7 to 10. Among Experimental Examples 16 to 33, Experimental Examples 16 to 28 and Experimental Examples 30 to 33 may be examples, and Experimental Example 29 may be a comparative example. (2-3) Observation of the fracture position The thermal transfer recording medium manufactured in each experimental example was slit into a ribbon shape with a predetermined width and wound into a roll, and then set in 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 outside air temperature of 25°C, the energy value applied to the thermal head, which was pre-set in the thermal transfer printer, was set separately to low energy (0.25 mJ / dot: 25 V (0.34 W / dot) / 750 μsec, the reaching temperature T R1 : 80°C, black) and high energy (0.34 mJ / dot: 25 V (0.34 W / dot) / 1000 μsec, the reaching temperature T R2 : 140°C, red), and a solid image of 70 mm square was recorded on the surface of a label material for printing variable information [a polyester film (white, glossy), FR1415-50 manufactured by Lintec Corporation]. In both cases, since a peeling distance of 110 mm was ensured in the thermal transfer printer, the peeling process was performed after sufficient cooling (below 60°C). The cross-section of the obtained solid image was observed using a transmission electron microscope (TEM: HT7820 manufactured by Hitachi High-Tech Corporation, acceleration voltage 100 kV). For each of the black transfer and red transfer, it was confirmed at which position of the thermal transfer recording medium the fracture occurred. The fracture position was classified in the following peeling modes.

[0195] First peeling mode: Between the base material layer and the first thermal transfer layer (interface fracture, see Fig. 10) Second peeling mode: Inside the first thermal transfer layer (cohesive fracture, see Fig. 11) Third delamination mode: Between the intermediate layer and the second thermal transfer layer (interfacial fracture, see Figure 12) Fourth delamination mode: Inside the second thermal transfer layer (cohesive failure, see Figure 13) Fifth delamination mode: Inside the intermediate layer (cohesive fracture, see Figure 14) Sixth delamination mode: Between the mixed layer and the second thermal transfer layer (interfacial fracture, see Figure 15) The results are shown in Tables 7-10. In Tables 7-10, the 1st to 6th delamination modes are indicated only by the numbers enclosed in circles. In addition, if multiple delamination modes are shown in Tables 7-10, it indicates that different delamination modes are occurring in the in-plane direction of the thermal transfer recording medium. Furthermore, since Experimental Example 29 has a layer structure without an intermediate layer, the delamination modes in the lower row of Table 7, strictly speaking, represent cohesive failure and interfacial failure occurring in the state where the intermediate layer 51 is omitted, as shown in Figures 13 and 15.

[0196] [Table 7]

[0197] [Table 8]

[0198] [Table 9]

[0199] [Table 10]

[0200] From a comparison of experimental examples 16-28 and 29 in Tables 7-9, it was found that the desired peeling mode can be achieved by adjusting the balance of the SP values ​​of the constituent components of the first thermal transfer layer, the second thermal transfer layer, and the intermediate layer, for example, by referring to Figure 17. As a result, it was found that a thermal transfer recording medium can be obtained in which the colors do not easily become muddy even when thermal transfer recording is performed continuously, the colors are clearly separated into two colors, and moreover, characters with excellent clarity can be recorded without causing excess peeling.

[0201] From a comparison of Experimental Examples 16-27 and Experimental Example 28, it was found that using a thermoplastic elastomer as the intermediate layer is preferable when considering further improvement of continuous recording performance.

[0202] From a comparison of Experimental Example 16 and Experimental Example 26, it was found that the epoxy resin used to form the first heat transfer layer has a softening point of 95°C or higher, is more preferably 110°C or higher, and is particularly preferably 125°C or higher. Furthermore, from a comparison of Experimental Example 16 and Experimental Example 27, it was found that it is preferable to incorporate a tackifier together with an acrylic adhesive in the epoxy resin used to form the first heat transfer layer.

[0203] Experimental Examples 16 and 30-33 showed that practically sufficient continuous recording performance and clarity can be achieved even when the amount of the intermediate layer coating is changed. Of Experimental Examples 16 and 30-33, Experimental Examples 16, 31, and 32 were found to be particularly excellent in terms of continuous recording performance and clarity. In Experimental Examples 16, 31, and 32, the intermediate layer is the thinnest (lowest coating amount) among the layers constituting the thermal transfer recording medium, and the thickness (coating amount) of the intermediate layer is large enough to fully exhibit the effect of introducing the intermediate layer.

[0204] In other words, in Experimental Example 33, among the layers constituting the thermal transfer recording medium, the intermediate layer was not the thinnest but relatively thick, so the transferred area (excess peeling) became large and the sharpness decreased. Usually, as in Experimental Example 33, when the thickness of one of the adjacent layers closer to the heat source increases, the reaching temperature at the interface between the one layer and the other layer decreases, so it is considered that the transfer area decreases. However, at the interface between the intermediate layer and the second thermal transfer layer, when the interface reaching temperature drops, a phenomenon may occur where the adhesive force between the intermediate layer and the second thermal transfer layer (between "51" and "52" in Fig. 6) is maintained relatively low. As a result, at the part around the barcode, the adhesive force between the intermediate layer and the second thermal transfer layer becomes relatively lower than the adhesive force between the label material and the second thermal transfer layer (between "2" and "52" in Fig. 6), and it is considered that breakage occurs between the intermediate layer and the second thermal transfer layer and the excess peeling becomes large.

[0205] On the other hand, in Experimental Example 30, among the layers constituting the thermal transfer recording medium, the intermediate layer was the thinnest, but since the coating amount was a rather small amount of 0.1 g / m 2 it could not sufficiently fulfill the original role of the intermediate layer, and a decrease was confirmed in both continuous recording property and sharpness.

Explanation of Reference Numerals

[0206] 1: Printing device 2: Printer tape 3: Ink ribbon 6: Thermal head 20: Heating element 31: Printing surface 32: Back surface 35: Base material layer 36: First ink layer 37: Second ink layer 42: First part 43: Second part 44: Printing pattern 45: Red pattern 46: Black pattern 47: Thermal transfer recording medium 48: Base material layer 50: First thermal transfer layer 51: Intermediate Layer 52: Second Hot Write Layer 61: Hybrid Layer 62: Material 1 63: Material 2 64: Material 3 65: Material 4 66: Material No. 5 F1: External Force T1: First temperature T2: Second temperature T3: Third temperature T R1 : Arrival temperature T R2 : Arrival temperature

Claims

1. A substrate layer having a first surface and a second surface, The substrate layer comprises a first thermal transfer layer, an intermediate layer, and a second thermal transfer layer, which are laminated in direct contact with each other in order on the first surface of the substrate layer. The aforementioned intermediate layer comprises a styrene-based thermoplastic elastomer. A thermal transfer recording medium wherein the first thermal transfer layer is laminated in direct contact with the first surface.

2. The thermal transfer recording medium according to claim 1, wherein the styrene-based thermoplastic elastomer has a melt mass flow rate (MFR) of 1000 g / 10 min or less at a temperature of 190°C and a load of 2.16 kg, as determined by the measurement method specified in ISO 1133-1:2011.

3. The thermal transfer recording medium according to claim 1 or 2, wherein the styrene-based thermoplastic elastomer comprises at least one of styrene-butadiene-styrene block copolymer (SBS) and styrene-ethylene-butene-styrene block copolymer (SEBS).

4. The thermal transfer recording medium according to claim 1 or 2, wherein the styrene-based thermoplastic elastomer comprises a styrene-based thermoplastic elastomer containing styrene in a content of 10% by mass or more and 70% by mass or less.

5. The thermal transfer recording medium according to claim 1 or 2, wherein the first thermal transfer layer comprises an epoxy resin and an acrylic adhesive.

6. The thermal transfer recording medium according to claim 1 or 2, wherein the second thermal transfer layer comprises a thermoplastic resin and a wax.

7. A thermal transfer recording medium comprising a substrate layer, a first ink layer containing a first ink, an intermediate layer containing a thermoplastic elastomer, 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 printing medium, In the first state, when the thermal transfer recording medium is heated to a first temperature or higher and a second temperature or lower, and then cooled to a third temperature or lower, an external force is applied to the substrate layer and the second ink layer in a direction away from each other, causing a fracture between the first ink layer and the substrate layer or within the first ink layer. In the second state, when the thermal transfer recording medium has been heated to a temperature above the second temperature and then cooled to a temperature below the third temperature, when the external force is applied, the first ink layer and the second ink layer are fractured or within the second ink layer. A thermal transfer recording medium wherein the first temperature is higher than the third temperature.

8. When the external force is applied in the first state, the breaking strength between the first ink layer and the substrate layer or within the first ink layer is the smallest among the thermal transfer recording media. The thermal transfer recording medium according to claim 7, wherein when the external force is applied in the second state, the fracture 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 mediums.

9. The thermal transfer recording medium according to claim 7 or 8, wherein when the external force is applied in the second state, the intermediate layer and the second ink layer are fractured.

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

11. The thermal transfer recording medium according to claim 9, wherein the intermediate layer comprises a styrene-based thermoplastic elastomer.

12. The thermal transfer recording medium according to claim 11, wherein the styrene-based thermoplastic elastomer comprises at least one of styrene-butadiene-styrene block copolymer (SBS) and styrene-ethylene-butene-styrene block copolymer (SEBS).

13. The thermal transfer recording medium according to claim 12, wherein the styrene content in the styrene-based thermoplastic elastomer is 10% by mass to 70% by mass.

14. The thermal transfer recording medium according to claim 9, wherein the intermediate layer comprises an acetate-based thermoplastic elastomer.

15. The thermal transfer recording medium according to claim 14, wherein the acetate ester-based thermoplastic elastomer comprises an ethylene-vinyl acetate copolymer (EVA).

16. The thermal transfer recording medium according to claim 9, wherein in the second state, the first ink layer and the intermediate layer are mixed.

17. The thermal transfer recording medium according to claim 7 or 8, wherein when the external force is applied in the second state, it breaks within the intermediate layer.

18. The thermal transfer recording medium according to claim 17, wherein when the external force is applied in the second state, the fracture strength in the intermediate layer is the smallest among the thermal transfer recording media.

19. The first ink layer comprises at least a first material and a second material having a higher solubility parameter (SP value) than the first material. The aforementioned intermediate layer includes at least a third material, The thermal transfer recording medium according to claim 7 or 8, wherein the second ink layer comprises at least a fourth material and a fifth material having a lower solubility parameter (SP value) than the fourth material.

20. The first state is a state in which the substrate layer of the thermal transfer recording medium is heated to a temperature of 1 or higher and 2 or lower, and then cooled to 3 or lower. The thermal transfer recording medium according to claim 7 or 8, wherein the second state is a state in which the substrate layer of the thermal transfer recording medium has been heated to a temperature exceeding the second temperature and then cooled to a temperature below the third temperature.

21. The thermal transfer recording medium according to claim 1 or 7, wherein the intermediate layer is the thinnest of the layers constituting the thermal transfer recording medium.

22. A heating step involves heating a thermal transfer recording medium, in which a substrate layer, a first ink layer containing a first ink, an intermediate layer containing a thermoplastic elastomer, and a second ink layer containing a second ink are laminated in this order, while in contact with a printing medium. A cooling step for cooling the thermal transfer recording medium that has been heated by the heating step, A printing apparatus that performs a transfer step of transferring at least a portion of the first ink and the second ink to a printing medium by applying an external force to the substrate layer and the second ink layer of the thermal transfer recording medium, which have been cooled by the cooling step, in a direction away from each other, In the heating step and the cooling step, The first portion of the thermal transfer recording medium is heated to a temperature of 1 or higher and 2 or lower, and then cooled to a temperature of 3 or lower to reach a first state; the second portion of the thermal transfer recording medium is heated to a temperature exceeding the 2nd temperature, and then cooled to a temperature of 3 or lower to reach a second state; In the aforementioned transfer process, By applying the aforementioned external force, the thermal transfer recording medium is fractured in the first portion of the thermal transfer recording medium between the first ink layer and the substrate layer or within the first ink layer, and the first ink and the second ink are transferred to the printing medium. A printing apparatus that, by applying the aforementioned external force, breaks the thermal transfer recording medium between the first ink layer and the second ink layer or within the second ink layer in the second portion of the thermal transfer recording medium, thereby transferring the second ink to the printing medium.

23. A thermal transfer recording medium according to claim 1 or 7, A cassette containing a printing medium on which a portion of the thermal transfer recording medium is thermally transferred.

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