JP4022224B2 - Method for producing thermal recording printed matter and apparatus for producing thermal recording printed matter - Google Patents

Description

The present invention relates to a method for producing a sensitive thermal recording prints, and apparatus for producing thermal recording print.

  A conventional thermal recording printed matter is formed by laminating a thermal recording layer on the surface side of a support. In order to perform printing on the thermal recording printed matter, as an example, the heating element of the print head is brought into contact with the thermal recording printed matter, and in this state, the heating element generates heat, and the thermal recording layer is colored. As a result, the thermosensitive coloring layer develops color, and desired characters and figures are recorded.

  In such a thermal recording medium, as a method for forming a thermal recording layer on a support, thermal ink is applied using a coating device such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, or a lip coater. The method to work is used. At this time, as the support, roll paper having a width of about 1 m and several thousand meters, or a large sheet is used. A heat-sensitive recording medium having a heat-sensitive recording layer formed on a support is cut with a slitter, cutter, etc., and processed into a heat-sensitive recording medium such as a small roll-shaped heat recording medium having a desired length and width, or a heat-sensitive recording print such as a heat-sensitive label. Is done.

  For example, in a thermal recording printed material manufacturing apparatus using a roll-shaped thermal recording medium, a transport unit that pulls and transports the thermal recording medium set in the manufacturing apparatus from the roll state, and a thermal sensor that is pulled out and transported from the roll state. The printer includes a print head for coloring and printing the thermal recording medium by generating heat by contacting the recording medium and a cutter for cutting the thermal recording medium drawn from the roll state to a desired length. The thermal recording medium is printed by causing the print head to generate heat based on the print data, and then cut into a desired length by a cutter (see, for example, Patent Documents 1 and 2).

  The heat-sensitive recording medium is white on both the front and back surfaces in the state before color is generated due to the heat generated by the print head, and the heat-sensitive recording layer is colored by the heat generated by the print head. For example, it develops in a color such as black, red, and blue. Some heat-sensitive recording media have a plurality of regions that develop different colors on a support.

Japanese Patent Laid-Open No. 2001-180060 JP 2002-103286 A

  When the thermal recording medium set in the thermal recording printed material manufacturing apparatus is cut, a part of the thermal coloring layer is peeled off from the support, and fine powder such as pigment is generated. For example, when the support is paper, there is a problem that the amount of fine powder generated increases.

  Such fine powder adheres to the cut heat-sensitive recording medium and is carried, and adheres to other places. For example, paper dust adheres to a cutter or a print head. When the fine powder adheres to the cutter, the cutter is susceptible to damage such as blade spillage by performing a cutting operation with the cutter to which the fine powder is adhered, and the durability of the cutter is reduced. Also, if fine powder adheres to the print head, the adhering fine powder becomes an abrasive between the print head and the heat-sensitive recording medium and damages the protective layer of the print head, reducing the durability of the print head. .

  As another problem, in the case of a heat-sensitive recording medium in which a heat-sensitive color-developing layer that forms multiple colors is formed, the color tone before color development is almost transparent and has a white color tone. It is difficult to identify the color tone. For this reason, there is a disadvantage in that it is not possible to know in advance what color the thermosensitive coloring layer will color when the thermal recording medium is printed by the print head. In particular, in the case of a thermal recording medium having a plurality of color development areas, the state before color development is almost transparent and white, so the color development area and color hue of such a thermal recording medium cannot be known in advance, and test printing is performed. There is also an inconvenience.

  An object of the present invention is to suppress the generation of fine powder when a thermal recording medium is cut, and to prevent damage to a cutter or a print head provided in the manufacturing apparatus.

The present invention relates to a method for producing a thermal recording print comprising a thermal recording medium having a thermal coloring layer formed on a support , wherein one of the regions of the thermal coloring layer is formed by a thermal head that comes into contact with a platen via the thermal recording medium. Developing a partial area, thereby increasing the adhesion between the support and the thermosensitive coloring layer, and incorporating a pigment present in the vicinity of the surface of the thermosensitive coloring layer into the thermosensitive coloring layer; and the partial area A method of producing a thermal recording printed matter, wherein a plurality of thermal recording members are formed by the step of cutting the step, and the step of coloring the partial region is performed prior to the step of cutting the partial region, and A manufacturing apparatus embodying the manufacturing method is provided.

  If you use a thermal recording medium that has a thermal coloring layer that reduces the paper dust generated from the edges of the thermal recording printed matter and develops a different color tone, what color does the thermal recording medium color? It is possible to eliminate the need for test printing for confirming.

  A first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing an appearance of a manufacturing apparatus that uses a thermal recording medium to manufacture a thermal recording printed matter. The manufacturing apparatus 1 is an apparatus for manufacturing a thermal recording printed matter, for example, a thermal label 2a, manufactured by cutting a large thermal recording medium 2 (see FIG. 5) into a rectangular shape. In addition, the heat-sensitive recording medium 3 wound in a roll shape (see FIGS. 2 and 6) can be used. On the front side of the main body case 4 of the manufacturing apparatus 1, printing is performed on the outlet 5, the thermal label 2 a or the roll-shaped thermal recording medium 3 from which the thermal label 2 a or the roll-shaped thermal recording medium 3 is printed. A display unit 6 for displaying print data to be printed, a power switch 7 and a cutter switch 8 are provided. An insertion port 9 for inserting the thermal label 2a is provided on the upper surface of the main body case 4.

FIG. 2 is a side view showing the internal structure of the manufacturing apparatus 1 for manufacturing the thermal recording printed matter. In the main body case 4 , the conveyance roller 10, the guide plate 11, the sensor 12, the guide roller 13, the platen roller 14, the print head 15, the conveyance roller 16, the sensor 17, and the cutter 18 are directed from the insertion port 9 toward the carry-out port 5. Is arranged. For example, a thermal printer head is used as the print head 15. A thermal recording medium 3 wound in a roll shape is detachably stored below the guide plate 11 in the main body case 4 .

  The transport roller 10 is a roller that is connected to a drive motor 27 (see FIG. 3) and is rotationally driven. The thermal label 2a inserted from the insertion port 9 when the transport roller 10 is rotationally driven is downstream in the transport direction. Is transported toward the print head 15 side. The thermosensitive label 2 a inserted from the insertion port 9 proceeds along the upper surface of the guide plate 11.

  The sensor 12 is a reflection type sensor having a light emitting element and a light receiving element, and the light emitted from the light emitting element is reflected by the heat-sensitive recording medium 3 drawn from the roll state, and the reflected light is reflected by the light receiving element. The thermal recording medium 3 is detected by receiving the light.

  The guide roller 13 is a roller that is rotatably supported, and guides the thermal recording medium 3 drawn out from the roll state toward the print head 15 by bending it.

  The platen roller 14 is a roller that is connected to a drive motor 27 and is rotationally driven to function as a conveyance unit. The thermal recording medium 3 drawn out of the thermal label 2a or the roll state when the platen roller 14 is rotationally driven. It is conveyed toward the carry-out port 5 located on the downstream side in the conveyance direction.

  The print head 15 is supported by a head moving mechanism (not shown) and is provided so as to be able to contact and separate from the outer peripheral surface of the platen roller 14. A plurality of heat generating elements are arranged on the surface of the print head 15 that is in contact with the outer peripheral surface of the platen roller 14, and these heat generating elements are selectively heated based on print data. When the heat-sensitive label 2a or the heat-sensitive recording medium 3 pulled out from the roll state is sandwiched between the platen roller 14 and the print head 15, the heat-generating elements of the print head 15 are selectively heated, whereby the heat-sensitive label 2a. Alternatively, the portion of the heat-sensitive recording medium 3 drawn from the roll state that is in contact with the heat generating element that has generated heat develops color, and printing according to the print data is performed.

  The conveyance roller 16 is a roller that is connected to a drive motor 27 and is rotationally driven to function as a conveyance unit. The thermal recording medium 3 drawn out of the thermal label 2a or the roll state when the conveyance roller 16 is rotationally driven. It is conveyed toward the carry-out port 5 located on the downstream side in the conveyance direction.

  The sensor 17 is a reflection type sensor having a light emitting element and a light receiving element, similar to the sensor 12, and the light emitted from the light emitting element hits the thermal recording medium 3 or the thermal label 2a extracted from the roll state and is reflected. Then, the reflected light is received by the light receiving element to detect the thermal recording medium 3 or the thermal label 2a.

  The cutter 18 has a pair of cutter blades arranged to face each other, and the cutter blade is moved by driving of a cutter motor 28 (see FIG. 3) to cut the thermal recording medium 3 drawn from the roll state. To do. The cutting operation by the cutter 18 is performed after the heat-sensitive recording medium 3 is conveyed in a predetermined dimension after the cutter switch 8 is pressed and the conveyance is completed. The cut thermal recording medium 3 is discharged from the discharge port 5 as a thermal recording print 3a.

  FIG. 3 is a block diagram showing electrical connection of the manufacturing apparatus 1. The manufacturing apparatus 1 includes a controller 20 that controls each unit. The controller 20 stores a CPU (Central Processing Unit) 21 that executes various calculations and the like, various programs for the calculations and the like performed by the CPU 21, fixed data, and the like. A ROM (Read Only Memory) 22 to be stored, a RAM (Random Access Memory) 23 functioning as a work area of the CPU 21, and the like are connected by a bus line 24.

  The CPU 21 includes sensors 12 and 17 via the sensor drive unit 25, print head 15 via the head drive unit 15 a, drive motor 27 via the motor drive unit 26, and cutter motor 28 via the bus line 24. It is connected. The drive motor 27 is a stepping motor that rotationally drives the transport rollers 10 and 16 and the platen 14. In addition, although not shown, the manufacturing apparatus 1 includes a connection unit such as a cable terminal or a connector terminal, or an optical communication unit, and is connected to an external device such as a keyboard or a personal computer via the connection unit. It is configured to give information.

  FIG. 4 is a flowchart for explaining the operation in the manufacturing apparatus 1 when cutting the width direction of the thermal recording medium 3 after completion of printing into a line. In the manufacturing apparatus 1, a printing operation is performed by causing the print head 15 to generate heat with respect to the thermal recording medium 3 that is pulled out and conveyed, and a signal for cutting the thermal recording medium 3 is output during the printing operation. It is determined whether or not an input has been made (step S1). A signal for cutting the thermal recording medium 3 is input when the cutter switch 8 is pressed.

  When a signal for cutting the thermal recording medium 3 is input (Y in step S1), the print head 15 generates heat in a straight line shape along the width direction of the thermal recording medium 3 (step S2). Due to the heat generated in the shape, the thermal recording medium 3 is colored in a straight line along the width direction, and means for causing the thermal recording medium 3 to be colored in a straight line along the width direction is executed.

  After the heat-sensitive recording medium 3 is colored in a straight line along the width direction, the drive motor 27 is driven for a predetermined number of steps (step S3), and the drive motor 27 is driven for a predetermined number of steps to perform heat-sensitive recording. The color development area colored in the line shape of the medium 3 is conveyed to the cutting position by the cutter 18, and means for conveying the color development area colored in the line shape of the thermal recording medium 3 to the cutting position by the cutter 18 is executed.

  After the drive motor 27 has been driven for a predetermined number of steps in step 3, the cutter motor 28 is driven (step S4), and the color development region colored in a line shape on the thermal recording medium 3 by driving the cutter motor 28 is a cutter. A means for cutting the colored region colored in a line shape of the thermal recording medium 3 by the cutter 18 is executed. The above has been described with respect to the case where the cutting site is cut in a straight line. However, when the shape to be cut is a curve, for example, the color is developed following the shape of the curve to be cut.

  FIG. 5 is a plan view showing a large thermal recording medium 2 and a thermal label 2a as a thermal recording printed matter produced by cutting the thermal recording medium 2. As shown in FIG. By cutting one heat-sensitive recording medium 2 along the cutting lines a to f, 16 heat-sensitive labels 2a are manufactured. The recording surface of the thermal recording medium 2 is formed with stripes of three color development areas that produce different colors of red, blue, and black, and each thermal label 2a has the same arrangement of red, blue, and black development areas. It is cut at the position it has in the state.

  Such a thermosensitive recording medium 2 is manufactured by laminating a thermosensitive coloring layer on a support. As the support, for example, plastic films such as polyethylene, polyamide, polyester, polypropylene, vinyl chloride, and polyethylene terephthalate (PET), and paper such as fine paper and Japanese paper are used. The heat-sensitive color developing layer contains a color former, a developer, and a binder as main components, and contains auxiliary agents such as a color former and filler as necessary. As the color former, for example, leuco dyes such as triphenylmentane, fluorane, and phenothiazine are used. As the developer, for example, phenols, organic acids, solid acids and the like are used. Examples of the binder include water-soluble binders such as polyvinyl alcohol, cellulose derivatives, aqueous acrylic resins, and starch derivatives, and water-insoluble binders such as polystyrene and vinyl chloride-vinyl acetate copolymers.

  In the process of manufacturing the thermal label 2a by cutting the thermal recording medium 2, the cutting lines a and c in a partial area are heated with a thermal head (not shown) to cause color development in a line shape. And the thermal label 2a is manufactured by cut | disconnecting the color development area | region (area | region containing the cutting lines a and c) colored in the shape of a line.

  In this case, the width of the partial area that is a preset cutting area is the area that includes the cutting portion of the non-printing area, and is in the vicinity of the cutting position when cutting after coloring. A necessary minimum width is set in consideration of variations in the cutting position.

  Further, when the cut site is curved, the color is developed according to the cut shape. Further, although it is desirable that the entire region of the cutting site is colored, a predetermined effect can also be exhibited when only the main part of the cutting region is colored due to restrictions such as printing conditions.

  A region colored in each color is formed at the cut portion at the end of each thermal label 2a. Since the end of each thermal label 2a is at least a part of the non-printing area of the recording surface in normal use, there is no practical problem even if the end is colored in advance.

  Here, one side of the thermal label 2a is colored, and the colored area includes the three colored areas of the thermal label 2a. Therefore, when the thermal label 2a is heated, which area is colored in what color. Can know. For this reason, the direction at the time of inserting the thermosensitive label 2a from the insertion port 9 can be confirmed easily.

  Further, by heating the cut lines a and c on a partial area of the thermal recording medium 2 to cause color development, the degree of adhesion between the support constituting the thermal recording medium 2 and the thermal color development layer in the color development area. And the pigment existing in the vicinity of the surface of the thermosensitive coloring layer is taken into the thermosensitive coloring layer, so that even if the colored cutting lines a and c are cut, the generation of fine powder such as pigment is suppressed. In the process of manufacturing the thermal label 2a by cutting the thermal recording medium 2, in order to further reduce the generation of fine powder, it is preferable to heat all the cutting lines a to f to cause color development. .

  In this case, in the present embodiment, since the partial area is heated by a thermal head (not shown), it is possible to more effectively improve the adhesion of the coloring layer to the support. That is, the thermal head normally heats the thermal recording medium in a pressurized state.

  Then, by coloring the cut site of the thermal recording medium 2 and cutting the colored area to suppress the generation of fine powder during cutting, various inconveniences caused by the generation of fine powder can be prevented. The inconvenience caused by the generation of fine powder is, for example, that the fine powder adhering to the thermal label 2a adheres to the product or the like to lower the product image, or adheres to the cutter that cuts the thermal recording medium 2. is there. By performing a cutting operation with a cutter to which fine powder is adhered, the cutter is easily damaged such as blade spillage, and the durability of the cutter is reduced.

  FIG. 6 is a perspective view showing the thermal recording medium 3 wound in a roll shape. Similar to the thermal recording medium 2 described with reference to FIG. 5, the thermal recording medium 3 has stripes in which three color development regions that generate red, blue, and black colors are formed on the recording surface of the thermal recording medium 3. Is formed. When this thermal recording medium 3 is set in the manufacturing apparatus 1 and used, printing according to the print data is performed by the print head 15 on the thermal recording medium 3 pulled out from the roll state. 18 is cut as thermal recording printed matter 3a. The position cut by the cutter 18 in the heat-sensitive recording medium 3 is heated by the print head 15 along the width direction of the heat-sensitive recording medium 3 and colored in a line shape.

  For this reason, when the heat-sensitive recording medium 3 in use is temporarily removed from the manufacturing apparatus 1 and then set in the manufacturing apparatus 1 again, what color the heat-sensitive recording medium 3 is colored in? Can be easily confirmed.

  FIG. 7 is a schematic cross-sectional view of the heating area and the non-heating area of the thermal recording medium 3. By heating the cutting position of the thermal recording medium 3 by the cutter 18 to cause color development, as shown in FIG. 7, the support 51 constituting the thermal recording medium 3 and the thermal coloring layer 52 are in close contact with each other in the color development region. As the temperature increases, the pigment 53 existing in the vicinity of the surface of the thermosensitive coloring layer 52 is taken into the thermosensitive coloring layer, so that generation of fine powder such as the pigment 53 is suppressed even if the colored coloring area is cut.

  FIG. 8 shows the results of experiments on how the amount of fine powder generated differs when cutting the colored areas when cutting the heat-sensitive recording media 3 and 2a and when cutting the non-colored areas. It is explanatory drawing shown. Since the amount of fine powder generated is determined by the adhesion between the support and the thermosensitive coloring layer, the adhesion of the thermosensitive coloring layer was evaluated, and the adhesion was evaluated by the cross cutting method defined in JIS. The evaluation sample used was a printer in which a color development region B having a width of 20 mm was formed at the center of a thermal recording medium A having a width of 100 mm under standard printing conditions. A cross-cut portion C in which 10 cuts were made in a vertical and horizontal cross at intervals of 1 mm was formed with a cutter using a cross-cutting jig (Cortech Co., Ltd .: cross cut guide 1.0). The cross-cut portion C was formed so as to cover the coloring area B and the non-coloring area. Adhesive tape D was applied to cross-cut portion C formed in this way, adhesive tape D was peeled off at an angle of 90 degrees from one side, and the presence or absence of the thermosensitive coloring layer adhered to adhesive tape D was examined. As the adhesive tape, Scotch's “transparent adhesive tape” model “BH-18” is suitable.

  As a result, it was confirmed that a white thermosensitive coloring layer adhered to the adhesive tape D from the non-coloring region. On the other hand, the phenomenon that the thermosensitive coloring layer peeled off from the coloring area B and adhered to the adhesive tape D was not observed. As is clear from this experiment, in the color development region B, a significantly superior adhesive force is generated between the heat-sensitive color development layer and the support as compared with the non-color development region, and generation of fine particles can be suppressed. found. Further, as described above, by using a heating means such as a thermal head, the heat-sensitive color forming layer is colored while being pressed, so that the heat-sensitive color developing layer has an effect of further improving the adhesion to the surface of the support. It is.

  FIG. 9 is a flowchart for explaining the operation of cutting the thermal recording medium 3 after the printing in the thermal recording printed material manufacturing apparatus 1 and thereafter coloring the cut portion. As described above, the embodiment has been described in the case of having the step of cutting after coloring the cut site before cutting the thermal recording printed matter. In the following, the second case of coloring the cut site after cutting is described. The embodiment will be described.

  Here, after cutting the thermal recording medium 3 using the thermal recording printed material manufacturing apparatus 1, the operation in the case of coloring the thermal coloring layer at the cut site will be described with reference to the flowchart of FIG. 9.

  In the manufacturing apparatus 1, a printing operation is performed by causing the print head 15 to generate heat with respect to the thermal recording medium 3 that is pulled out and conveyed, and a signal for cutting the thermal recording medium 3 is output during the printing operation. It is determined whether or not an input has been made (step S11). A signal for cutting the thermal recording medium 3 is input when the cutter switch 8 is pressed.

  When a signal for cutting the thermal recording medium 3 is input (Y in step S11), the drive motor 27 is driven for a predetermined number of steps (step S12), and the drive motor 27 is driven for a predetermined number of steps. Thus, the partial area of the thermal recording medium 3 to be developed is conveyed to the cutting position by the cutter 18, and means for conveying the partial area of the thermal recording medium 3 to be developed to the cutting position by the cutter 18 is executed. The

  After the drive motor 27 has been driven a predetermined number of steps in step 3, the cutter motor 28 is driven (step S13), and the cutter motor 28 is driven so that a partial area to be colored in the thermal recording medium 3 is cut by the cutter 18. A means for cutting a partial area of the thermal recording medium 3 to be colored by the cutter 18 is executed.

  A part of the heat-sensitive recording medium 3 to be colored is cut by the cutter 18, and then the drive motor 27 is driven by a predetermined number of steps in a direction opposite to that of step S1 (step S14). By being driven several times, a partial area of the thermal recording medium 3 to be colored returns to the position of the print head 15.

  The print head 15 is partially heated along the width direction of the thermal recording medium 3 (step S15), and this partial area is heated to cause the thermal recording medium 3 to develop color along the width direction. Means for coloring the end of the thermal recording medium 3 cut by the cutter 18 along the width direction of the medium 3 is executed.

  As for the color-forming layer at the end of the thermal recording medium 3 cut in this way, the amount of fine powder generated when the developed color area is cut and when the non-colored area is cut as in the first embodiment. As a result of experimenting on how these differ, almost the same result was obtained. However, since the heat-sensitive color developing layer in a part of the region of the heat-sensitive recording medium 3 is cut without color development, fine powder is generated at the time of cutting, so that the heat-sensitive recording medium 3 (heat-sensitive recording printed matter 3a after cutting) is generated. ) Is effective in suppressing the degree of generation of fine powder from the cutting site, but the first embodiment is more effective in that it cuts after coloring a partial region to be cut first as a whole. .

  In the case of producing a thermal recording printed material by cutting the printed thermal recording medium as in the present embodiment, in the case where the thermal coloring layer at the edge portion cut after cutting is colored, the print head 15 is used. However, even if the heat-sensitive color developing layer is made non-contact, for example, by heating with a nichrome wire heater or the like, the heat-sensitive color developing layer is made dense and the adhesion to the support is improved. Since there is an effect of increasing, there is an effect of suppressing the generation of fine powder. As a secondary effect, as described above, there is an effect that the positions where the respective colors are formed can be visually recognized on the thermal recording medium in which the thermal coloring layers having different tones are formed.

It is a perspective view which shows the external appearance of the manufacturing apparatus of the thermal recording printed matter of one embodiment of this invention. It is a side view which shows the internal structure of the manufacturing apparatus of a thermal recording printed matter. It is a block diagram which shows the electrical connection of the manufacturing apparatus of a thermal recording printed matter. It is a flowchart explaining the operation | movement which cut | disconnects the thermal recording medium after completion | finish of printing in the manufacturing apparatus of a thermal recording printed matter. FIG. 2 is a plan view showing a large thermal recording medium and a thermal label produced by cutting the thermal recording medium. It is a perspective view which shows the thermal recording medium wound by roll shape. It is a cross-sectional schematic diagram of the heating area | region and non-heating area | region of a thermosensitive recording medium. When cutting a thermal recording medium, it is explanatory drawing which shows the result of having experimented how the generation amount of a fine powder differs by the case where a color development area | region is cut | disconnected and a non-color development area | region is cut | disconnected. It is a flowchart explaining the operation | movement which cut | disconnects a thermal recording medium after completion | finish of printing in the manufacturing apparatus of a thermal recording printed matter, and color-develops a cutting part after that.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Thermal recording medium 2a Thermal label 3 Thermal recording medium 15 Print head

Claims (5)

In a method for producing a thermal recording printed material comprising a thermal recording medium having a thermal coloring layer formed on a support ,
A thermal head that contacts the platen via the thermal recording medium causes a color of a part of the thermal coloring layer to increase the adhesion between the support and the thermal coloring layer, and A method for producing a thermal recording print, comprising producing a plurality of thermal recording prints by a step of incorporating a pigment present in the vicinity of the surface into the thermal coloring layer and a step of cutting the partial region.   2. The method for producing a thermal recording printed material according to claim 1, wherein the step of coloring the partial region is performed prior to the step of cutting the partial region. The method for producing a thermal recording printed matter according to claim 1 or 2, wherein a thermosensitive coloring layer that develops a different color tone is formed on the support . A manufacturing apparatus for manufacturing a plurality of thermal recording prints by cutting a partial region of a thermal recording medium on which a thermosensitive coloring layer for color development is formed on a support ,
A part of the thermal recording medium is colored by a thermal head that contacts the platen via the thermal recording medium , thereby increasing the adhesion between the support and the thermal coloring layer and near the surface of the thermal coloring layer. Coloring means for incorporating the pigment present in the heat-sensitive coloring layer ,
Cutting means for cutting the partial region;
An apparatus for producing a thermal recording printed matter, comprising: 5. The apparatus for producing a thermal recording printed material according to claim 4 , wherein the thermal recording printed material is formed with a thermal coloring layer that develops colors of different colors.

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