JP2015107591A - Production method of thermal transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a thermal transfer sheet comprising a layer formed by suppressing generation of streaks using aqueous coating liquid.SOLUTION: The production method comprises the steps of: preparing a base material; and forming a layer by coating aqueous coating liquid including at least water and binder on one of surfaces of the base material by using a gravure coating device comprising a plate cylinder on which plural concave ink feeding parts 31 are formed on a printing plate 30, through a gravure printing system. The concave ink feeding parts on the gravure coating device comprise: two or more convex line material parts 32 disposed with an interval; two or more coating liquid channels 33 for coupling between the concave ink feeding parts, they surround the respective concave ink feeding part. A total ratio of two or more coating liquid channel parts for forming an outer periphery with respect to the outer periphery of the concave ink feeding part, is 35-55%.

Description

  The present invention relates to a method for producing a thermal transfer sheet.

Conventionally, various thermal transfer recording methods are known, and among them, a widely used method includes a thermal melting transfer method and a thermal sublimation transfer method.
In the heat-melt transfer method, a heat transfer sheet in which a heat-melt ink layer in which a color material such as a pigment is dispersed in a binder such as a heat-meltable wax or resin is supported on a base sheet such as a plastic film is used. In addition, energy corresponding to image information is applied to a heating device such as a thermal head, and a color material is thermally transferred onto a transfer paper such as paper or a plastic sheet together with a binder to form an image. In such a hot-melt transfer method, various types of printing can be easily formed with a thermal head, etc., so that characters and barcodes can be printed for managing products at factories and the like. It's being used.
On the other hand, in the heat-sensitive sublimation transfer method, a sublimation dye is used as a color material, and the dye in the dye layer of the thermal transfer sheet is thermally transferred to the dye-receiving layer of the thermal transfer image-receiving sheet to form an image. In this method, the amount of heating is adjusted by the thermal head of the printer during thermal transfer, and a large number of three or four colors are transferred to the dye-receiving layer of the thermal transfer image-receiving sheet, and gradation printing is performed. Can be reproduced. The image formed in this way is very clear and excellent in transparency because the color material used is a dye, so it is excellent in halftone reproducibility and coordination, and is a full-color photographic image. It is possible to form a high-quality image comparable to

A thermal transfer sheet is generally provided on one surface of a substrate sheet such as a plastic film, as appropriate for each transfer method, with a thermal melt transfer layer including a thermal melt ink layer, a dye layer including a heat transferable dye and a binder, and the like. It is formed by coating. The layer formed in this way preferably has a uniform thickness in order to improve the quality of the transferred image to be formed. For such purposes, a gravure printing method is generally employed (for example, Patent Documents). 1).
In the gravure printing method, printing is performed by transferring ink filled in minute recesses called cells formed on the surface of the plate cylinder to a transfer material. Specifically, first, the plate cylinder is dipped in an ink reservoir, and the cells in the image area are filled with ink. Next, the ink on the plate surface is scraped off by a doctor blade so that only the cells are filled with ink. Following this, the printing substrate is made to enter between the plate cylinder and the impression cylinder, and the ink in the cells in the image area is transferred onto the printing substrate by pressing with the impression cylinder.

JP-A-6-1077

As the coating liquid used for forming the layer of the thermal transfer sheet, it is desirable to use a water-based coating liquid from the viewpoint of influence on the human body and the environment. However, when a water-based coating liquid is applied to a substrate by a gravure printing method, the coating liquid does not scrape off the coating liquid on the plate surface by the doctor blade, and the coating liquid runs on the doctor blade. It was more likely to occur than when an organic solvent-based coating solution was used. When the coating liquid rides on the doctor blade, problems such as streaks occur in the thermal transfer sheet due to the influence of the excessive coating liquid and the dried product.
For example, when the coating liquid rides on the doctor blade, the dried product resulting from the drying of the coating liquid then drops from the doctor blade onto the plate surface and is carried by the plate cylinder to adhere to the substrate. As the dried coating liquid accumulates on the blade, the blade edge of the doctor blade becomes thick, and the coating liquid on the plate surface is scraped excessively by the doctor blade, causing streaks on the thermal transfer sheet, etc. The problem occurs.

  The present invention has been made in view of the above problems, and a method for producing a thermal transfer sheet capable of obtaining a thermal transfer sheet having a layer formed by suppressing the generation of streaks while using an aqueous coating solution. The purpose is to provide.

The method for producing a thermal transfer sheet according to the present invention includes a step of preparing a substrate,
On one surface of the substrate, an aqueous coating solution containing at least a binder and water is applied by a gravure printing method using a gravure coating apparatus having a plate cylinder in which a plurality of concave ink supply portions are provided on the plate surface. A method of manufacturing a thermal transfer sheet having a step of forming a layer by
The concave ink supply unit in the gravure coating apparatus includes two or more convex wire rods arranged at intervals, and two or more coating liquid channels connecting the concave ink supply units. The total ratio of the two or more coating liquid flow path portions constituting the outer periphery to the outer periphery of the concave ink supply unit is 35 to 55%.

  In the method for producing a thermal transfer sheet according to the present invention, in the plate cylinder, the concave ink supply portion and the coating liquid flow path constitute a concave portion that is continuous in the rotation direction of the plate cylinder. It is preferable to do. This makes it easier for the coating liquid to flow on the plate surface of the plate cylinder, prevents the coating liquid from running on the doctor blade, and increases the effect of suppressing the generation of streaks in the layer formed on the thermal transfer sheet. Can do.

  In the method for producing a thermal transfer sheet according to the present invention, in the plate cylinder, the concave ink supply unit is surrounded by a quadrangle between the convex wire part and the coating liquid flow path, and each corner of the quadrangle is formed. It is preferable that the corner portion has a cutout portion formed by cutting out at least one convex wire portion, and the coating liquid channel is formed of the cutout portion. This makes it easier for the coating liquid to flow on the plate surface of the plate cylinder, further prevents the coating liquid from running on the doctor blade, further suppresses the generation of streaks in the layer formed on the thermal transfer sheet, and The uniformity of the surface of the layer can be further improved.

  In the method for producing a thermal transfer sheet according to the present invention, it is preferable that a register mark for alignment is further provided on the plate surface in the plate cylinder. Thereby, the position of the printing plate can be easily grasped.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the thermal transfer sheet which can obtain the thermal transfer sheet provided with the layer formed by suppressing generation | occurrence | production of a streak, using an aqueous coating liquid can be provided.

It is sectional drawing which shows typically an example of the thermal transfer sheet manufactured by this invention. It is sectional drawing which shows typically another example of the thermal transfer sheet manufactured by this invention. It is a top view which shows typically an example of the plate surface of the plate cylinder used in the manufacturing method of the thermal transfer sheet concerning this invention. It is the figure which expanded the concave ink supply part provided in the printing plate shown in FIG. FIG. 5 (A) is a plan view schematically showing another example of the plate surface of the plate cylinder used in the method for producing a thermal transfer sheet according to the present invention, and FIG. 5 (B) is shown in FIG. 5 (A). It is the figure which expanded the concave ink supply part provided in the printing plate surface to show. FIG. 6 (A) is a plan view schematically showing another example of the plate surface of the plate cylinder used in the method for producing a thermal transfer sheet according to the present invention, and FIG. 6 (B) is shown in FIG. 6 (A). It is the figure which expanded the concave ink supply part provided in the printing plate surface to show. 7A is a plan view schematically showing the plate surface of the plate cylinder used in Comparative Example 1, and FIG. 7B is an enlarged view of the cell provided on the plate surface shown in FIG. 7A. FIG.

The method for producing a thermal transfer sheet according to the present invention includes a step of preparing a substrate,
On one surface of the substrate, an aqueous coating solution containing at least a binder and water is applied by a gravure printing method using a gravure coating apparatus having a plate cylinder in which a plurality of concave ink supply portions are provided on the plate surface. A method of manufacturing a thermal transfer sheet having a step of forming a layer by
The concave ink supply unit in the gravure coating apparatus includes two or more convex wire rods arranged at intervals, and two or more coating liquid channels connecting the concave ink supply units. The total ratio of the two or more coating liquid flow path portions constituting the outer periphery to the outer periphery of the concave ink supply unit is 35 to 55%.

In a gravure coating apparatus, generally, a cell which is a concave depression for filling ink is provided on a plate surface of a plate cylinder. The concave ink supply unit in the present invention is a part corresponding to a cell of a conventional gravure coating apparatus. The inventors of the present invention have provided the concave ink supply section with two or more convex wire portions arranged at intervals, and two or more coating liquid flow paths connecting the concave ink supply sections. The total ratio of the two or more coating liquid flow path portions with respect to the outer periphery of the concave ink supply portion is within the specific range. Whereas the conventional general cell is not connected between adjacent cells, the concave ink supply part of the present invention is connected between the adjacent concave ink supply parts by a flow path for coating liquid, The total ratio of the coating liquid flow path portion with respect to the entire outer periphery of the concave ink supply portion is within the specific range. By providing such a concave ink supply part on the plate surface, the present inventors have found that the aqueous coating liquid runs on the doctor blade even when applying the aqueous coating liquid by the gravure printing method. It was found that it can be suppressed.
In conventional gravure coating equipment, when pressure is applied by the blade edge of the doctor blade, the water-based coating liquid runs on the doctor blade because the water-based coating liquid is more surface-coated than the organic solvent-based coating liquid. This is probably because the tension is high and the viscosity is low.
On the other hand, in the present invention, the aqueous coating liquid filled in the concave ink supply section moves between the concave ink supply sections via the coating liquid flow path connecting the concave ink supply sections. Therefore, even if the water-based coating liquid is pressed by the blade edge of the doctor blade, it can be released by moving to another concave ink supply section, so the water-based coating liquid on the doctor blade It is thought that the climbing of is suppressed. In addition, by setting the ratio of the total of the coating liquid flow path portion constituting the outer periphery to the outer periphery of the concave ink supply portion configured by the convex wire portion and the coating liquid flow path within the specific range. , While allowing the coating liquid to move between the concave ink supply sections, the concave ink supply section is sufficiently filled with the coating liquid, and the transfer of the coating liquid to the substrate can be performed satisfactorily Conceivable. In particular, by setting the total ratio of the flow path portion for the coating liquid to the outer periphery of the concave ink supply portion to be equal to or more than the above lower limit value, it is possible to suppress clogging of the coating liquid in the flow path for the coating liquid, It is considered that the occurrence of streaks due to the location where the coating liquid is clogged is also suppressed.
As described above, in the method for producing a thermal transfer sheet according to the present invention, even when an aqueous coating liquid is used in the formation of the layer of the thermal transfer sheet, the application of the coating liquid onto the doctor blade is suppressed. Accumulation of dry matter of the coating liquid on the top is prevented, and the dry matter adheres to the base material, streaks occur due to excessive scraping of the coating liquid with a doctor blade with a thickened blade edge, etc. Problems such as generation of streaks due to clogging of the coating liquid in the flow path for the working liquid can be solved, and a layer with higher uniformity can be formed.

FIG. 1 shows an example of a thermal transfer sheet produced by the present invention. A thermal transfer sheet 10 in FIG. 1 is an example of a thermal transfer sheet of a thermal melting type transfer system. 5 is provided in this order, and the back layer 6 is provided on the other surface of the substrate 1.
FIG. 2 shows another example of the thermal transfer sheet of the present invention. The thermal transfer sheet 20 in FIG. 2 is an example of a thermal transfer sheet of a heat-sensitive sublimation type transfer system, and a dye primer layer 21 and a dye layer 22 are provided in this order on one surface of the substrate 1, and the other of the substrate 1 The back surface layer 23 is provided on the surface.
The layer formed by applying the aqueous coating liquid by the gravure printing method may be any of the above layers. The layers listed in FIGS. 1 and 2 are examples of layers provided on the thermal transfer sheet, and the layers formed by applying the aqueous coating liquid in the manufacturing method according to the present invention are provided on the thermal transfer sheet. Other functional layers may be used. In addition, the thermal transfer sheet produced in the present invention has a layer that is not a layer formed by applying an aqueous coating solution in addition to a layer formed by applying an aqueous coating solution. It may be.
Hereinafter, each process which the manufacturing method of the thermal transfer sheet concerning this invention has is demonstrated.

<Base material preparation process>
The base material used for this invention is for supporting each layer provided in a thermal transfer sheet, The well-known material conventionally used as a base material of a thermal transfer sheet can be used. Specifically, it is not particularly limited as long as it has a certain degree of heat resistance and strength, for example, polyethylene terephthalate film, 1,4-polycyclohexylenedimethylene terephthalate film, polyethylene naphthalate film, polyphenylene sulfide film, Polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, cellulose derivatives such as cellulose acetate, polyethylene film, polyvinyl chloride film, nylon film, polyimide film, ionomer film and other resin films; condenser Papers such as paper, paraffin paper, and synthetic paper; non-woven fabrics; and composites of paper and non-woven fabrics and resins.
Although the thickness of the said base material is not specifically limited, Usually, it is 0.5-50 micrometers, Preferably it is 3-10 micrometers.

<Layer formation process>
In the method for producing a thermal transfer sheet according to the present invention, a gravure provided with a plate cylinder in which a plurality of concave ink supply portions are provided on a plate surface on one surface of the substrate with an aqueous coating solution containing at least a binder and water. It has the process of forming a layer by coating by a gravure printing method using a coating device.
The gravure coating apparatus used in the present invention is not particularly limited as long as the concave ink supply unit provided on the plate surface of the plate cylinder has the shape specified in the present invention, and is the same as the conventional gravure apparatus. The structure and material can be used.
In the present invention, the layer is formed, for example, by immersing the plate cylinder in an ink reservoir filled with the aqueous coating liquid, filling the concave ink supply section provided on the plate surface of the plate cylinder with the aqueous coating liquid, , Scrape off the aqueous coating solution on the plate surface with a doctor blade, allow the substrate to enter between the plate cylinder and the impression cylinder, and press the aqueous coating solution in the concave ink supply section onto the substrate by pressing with the impression cylinder. It can be performed by transferring to

The layer formed with the aqueous coating solution is not particularly limited. For example, in the case of a thermal transfer sheet of a hot melt transfer type, a release layer, a transferable protective layer, a transferable colored layer, a transferable adhesive layer, an antistatic layer. And one or more selected from the group consisting of the back layer.
In addition, the layer formed with the aqueous coating liquid is, for example, one or more selected from the group consisting of a dye primer layer, a dye layer, a back primer layer, and a back layer in the case of a thermal transfer sheet of a heat-sensitive sublimation transfer method. Can be mentioned. The layer is not limited to the above as long as it is a layer formed by applying an aqueous coating solution, and may be another functional layer provided on the thermal transfer sheet.

(Concave ink supply unit)
Hereinafter, the concave ink supply unit provided on the plate surface of the plate cylinder of the gravure coating apparatus used in the present invention will be described in detail.
The concave ink supply part of the present invention is a part corresponding to a cell in a conventional gravure coating apparatus, and connects between two or more convex wire parts arranged at intervals and the concave ink supply part. And two or more coating liquid channels, and the outer circumference of the concave ink supply section constituted by the convex wire portion and the coating liquid channel constitutes the outer circumference. The total ratio of the flow path portions for two or more coating liquids is 35 to 55%.
In the present invention, the convex wire portion is typically a linear member composed of two opposing long sides and two opposing short sides, and the concave ink supply portion is typically 2 It is surrounded by the long side part of two or more convex wire parts, and the two or more coating-liquid flow paths which connect between the said concave ink supply parts. Each of the long side and the short side is typically a straight line, but may be a curved line.
In the present invention, the outer periphery of the concave ink supply portion is surrounded by the inner wall of the convex wire portion constituting the concave ink supply portion and the virtual line extending along the inner wall of the convex wire portion. An outer periphery with a circular shape. In addition, when the line along the inner wall of the convex wire portion is a curve, a virtual line is drawn from the shape of the convex wire portion assuming that the shape surrounding the concave ink supply portion is, for example, an ellipse be able to.

FIG. 3 schematically shows an example of a plate surface of a plate cylinder used in the method for producing a thermal transfer sheet according to the present invention. The plate surface 30 shown in FIG. 3 is provided with a plurality of concave ink supply portions 31, each concave ink supply portion 31 including four convex wire portions 32 arranged at intervals and the concave ink supply. It is surrounded by four coating liquid flow paths 33 that connect the portions 31 to each other.
FIG. 4 shows an enlarged view of the concave ink supply unit 31 shown in FIG. 3, and an imaginary line extending along the inner wall of the convex wire portion in the outer periphery of the concave ink supply unit 31 is indicated by a dotted line. The concave ink supply part 31 shown in FIG. 4 is between the convex wire member parts 32a, 32b, 32c and 32d arranged at intervals and the other concave ink supply part adjacent to the concave ink supply part 31. The coating liquid flow paths 33a, 33b, 33c and 33d to be connected are surrounded, and the outer periphery of the concave ink supply part 31 is a portion La constituted by the convex wire parts 32a, 32b, 32c and 32d, It consists of Lb, Lc, and Ld, and parts Da, Db, Dc, and Dd that are constituted by coating liquid flow paths 33a, 33b, 33c, and 33d. That is, in the concave ink supply unit 31 shown in FIG. 4, the total of the coating liquid flow path portions constituting the outer periphery is the total of Da, Db, Dc, and Dd.

5 and 6 show another example of the plate surface of the plate cylinder used in the present invention and another enlarged view of the concave ink supply section provided on the plate surface.
A plate surface 30 shown in FIG. 5A is provided with a plurality of concave ink supply sections 31 surrounded by four convex wire sections 32 and four coating liquid flow paths 33. FIG. 5B is an enlarged view of the concave ink supply unit 31 provided on the printing plate shown in FIG. 5A, along the inner wall of the convex wire portion 32 in the outer periphery of the concave ink supply unit 31. The imaginary line extended is indicated by a dotted line.
The plate surface 30 shown in FIG. 6A has two concave ink supply portions 31a surrounded by two convex wire portions 32e and 32f and two coating liquid channels 33e and 33f. A concave ink supply part surrounded by two convex wire parts and two coating liquid channels, three convex wire parts 32f, 32g and 32h, and three coating liquid channels 33e and 33g , 33h, a plurality of concave ink supply portions surrounded by three convex wire portions and three coating liquid flow paths are provided. FIG. 6B is an enlarged view of the concave ink supply portions 31a and 31b provided on the printing plate shown in FIG. 6A. Of the outer periphery of each concave ink supply portion, convex wire portions 32e and 32f are provided. , 32g, and 32h, imaginary lines extending along the inner walls are indicated by dotted lines.
The plan view shape of the concave ink supply unit is not particularly limited, and is, for example, a quadrangle as shown in FIGS. 3, 4, 5 and 6, a polygon such as a triangle, a pentagon, and a hexagon, although not shown, and an ellipse. Examples include a shape and a circle. In addition, in this invention, the planar view shape of a concave ink supply part means the shape of the outer periphery of a concave ink supply part.
In addition, the concave ink supply part in this invention is not restricted to the form shown in FIGS. 3-6, It can change suitably in the range of this invention.

  In this invention, the ratio of the sum total of the said 2 or more coating-liquid flow path 33 part which comprises the said outer periphery with respect to the outer periphery of the said concave-shaped ink supply part 31 is 35-55%, and is 40-50%. Is preferred. When the ratio is equal to or greater than the lower limit value, the coating liquid can easily pass through the coating liquid flow path, so that a layer with higher uniformity can be formed. In addition, since the ratio is equal to or more than the lower limit value, the coating liquid is prevented from being clogged in the coating liquid flow path, and the fluidity of the coating liquid is improved. It is considered that the generation of streaks due to the phenomenon is also suppressed. When the ratio is equal to or less than the upper limit, the coating liquid is sufficiently filled in the concave ink supply unit, and it becomes easy to form a layer having excellent uniformity with a desired coating amount.

In the present invention, the concave ink supply part 31 has two or more convex wire portions 32 arranged at intervals, and two or more coating liquid streams connecting the concave ink supply parts 31. Since the channel 33 is surrounded by the channel 33, the concave ink supply unit 31 and the coating liquid channel 33 are open and continuous. .). In the present invention, since the coating liquid filled in the concave ink supply section can freely move in the continuous recess, even if the coating liquid is pressed by the blade edge of the doctor blade, another Since it is possible to relieve pressure by moving to the concave ink supply unit, it is considered that the application of the coating liquid onto the doctor blade is suppressed.
In the present invention, it is preferable that the concave ink supply part 31 and the coating liquid flow path 33 constitute a concave part (continuous concave part) that is continuous in the rotational direction of the plate cylinder. . Thereby, the coating liquid (ink) can easily flow on the plate surface of the plate cylinder, and the amount of the coating liquid (ink) riding on the doctor blade can be reduced.
Here, the concave part continuously opened in the rotational direction of the plate cylinder means that the concave part is opened continuously in the rotational direction of the plate cylinder and the end of the continuous concave part is not closed in the rotational direction. . Concave parts that are open and continuous in the rotational direction of the plate cylinder are continuous so that they can circulate around the plate surface, and the wraparound also includes the case of wrapping around without returning to the same point like a spiral. .
3, 5 </ b> A, and 6 </ b> A, the continuous concave path formed by the concave ink supply section 31 and the coating liquid flow path 33 is opened in the rotational direction of the plate cylinder. The path of the continuous recess is indicated by a dotted line. The continuous concave portions indicated by dotted lines in FIGS. 3, 5A, and 6A are all opened continuously in the rotation direction of the plate cylinder. In addition, the path | route comprised by the recessed part open | released and continuous in the rotation direction of a plate cylinder is parallel to the rotation direction of a plate cylinder, as shown to FIG. 5 (A) and FIG. 6 (A). Alternatively, it may meander as shown in FIG.
In the present invention, among others, on the plate surface of the plate cylinder, a continuous recess formed continuously in the direction of rotation of the plate cylinder and a continuous recess formed continuously in the direction intersecting with the direction of rotation of the plate cylinder. It is easy to flow on the plate surface of the plate cylinder because it has a passage for the coating liquid to escape when excess coating liquid is scraped off with a doctor blade. Therefore, it is preferable in that the generation of streaks in the layer formed using the aqueous coating liquid can be further suppressed, and a layer having more excellent uniformity can be formed.

In the present invention, in the plate cylinder, the concave ink supply unit is surrounded by a quadrangular shape between the convex wire portion 32 and the coating liquid channel 33, and at least two corners of the quadrilateral. It is preferable that at least one of the convex wire portions 32 has a cutout portion, and the coating liquid flow path 33 is formed of the cutout portion. Thereby, the filling property of the coating liquid in the concave ink supply unit is improved while ensuring the free movement of the coating liquid between the concave ink supply units and suppressing the generation of streaks.
In this case, it is preferable that the two corners located on the diagonal of the quadrangle are notches, and the straight line connecting the notches is in a direction less than ± 45 ° with respect to the rotation direction of the plate cylinder. Further, it is preferable that the direction is ± 30 ° or less with respect to the rotation direction of the plate cylinder from the viewpoint that the coating liquid easily flows on the plate surface of the plate cylinder.

In the present invention, in particular, from the viewpoint of being excellent in both the effect of suppressing the generation of streaks and the filling property of the coating liquid in the concave ink supply part, the concave ink supply part is provided with the convex wire part 32 in the plate cylinder. And at least two corners of the quadrangle, and at least one of the convex wire portions 32 is notched, and the coating liquid channel 33 is surrounded by a quadrangle. The liquid flow path 33 is composed of the notch, and the plate surface of the plate cylinder is opened in a direction intersecting with the rotation direction of the plate cylinder, and a continuous concave portion opened continuously in the rotation direction of the plate cylinder. It is preferable to have both continuous concave portions formed continuously. Examples of the concave ink supply unit 31 having such a shape include the concave ink supply unit 31 shown in FIGS. 3, 5, and 6.
Examples of the quadrangle include a square, a rectangle, a rhombus, and a parallelogram.
More preferably, in the plate cylinder, the concave ink supply part is surrounded by a square with the convex wire part 32 and the coating liquid flow path 33, and at least one convex part is formed at each corner of the square. The wire portion 32 has a cutout portion formed by cutting out, and the coating liquid flow path 33 is formed of the cutout portion. Examples of the concave ink supply unit 31 having such a shape include the concave ink supply unit 31 shown in FIGS. 3 and 5. In such a case, since the coating liquid is more likely to flow on the plate surface of the plate cylinder, the generation of streaks in the layer formed using the aqueous coating liquid is further suppressed, and the layer is more excellent in uniformity. Can be formed.

In the present invention, in particular, the concave ink supply part 31 is surrounded by four convex wire parts 32 and four coating liquid flow paths 33 in a quadrilateral shape, and at each corner part of the quadrangle. Of the two convex wire portions 32 intersecting when the extension line extending from the convex wire portion 32 is drawn, one of the convex wire portions 32 is notched, and the other convex wire portion. It is even more preferable that 32 is not cut and the two convex wire portions 32 are arranged in a substantially T shape. Examples of the concave ink supply unit 31 having such a shape include the concave ink supply unit 31 shown in FIG. As shown in FIG. 3, the concave ink supply unit 31 is configured by one convex wire portion 32 and one coating liquid channel 33 at each corner portion of a quadrangle. . In such a case, as described above, the coating liquid can easily flow on the plate surface of the plate cylinder, and the two convex wire portions 32 are arranged in a substantially T shape. The filling property of the coating liquid becomes better.
Although the concave ink supply unit 31 shown in FIG. 3 is not particularly limited, for example, first, a grid shape is provided by intersecting two types of linear part groups that form the convex wire part 32 on the plate surface of the plate cylinder, For each one of the other linear portions where one linear portion intersects with this, the other linear portion is cut out on both sides of the other linear portion, and the other linear portion also intersects with this one line It can be formed by being cut out on both sides of the one linear portion for every one of the linear portions.

The number of lines of the convex wire portion is not particularly limited as long as it is appropriately adjusted depending on the coating amount or the like, but is preferably in the range of 60 to 400 lines / inch.
In the present invention, the average of the height of the convex wire portion (depth of the concave ink supply portion) is not particularly limited, but is preferably 5 to 50 μm, and more preferably 10 to 20 μm.
Moreover, although the average of the length (l shown in FIG. 4) of the long side part of the said convex wire part is not specifically limited, It is preferable that it is 10-240 micrometers. In addition, the long side part of a convex wire part means the part which has the longest line segment or curve among the line segments or curves which comprise a convex wire part.

In the present invention, the aperture ratio in the plate surface of the plate cylinder (ratio of the concave portion with respect to the entire region when the entire plate surface of the plate cylinder is viewed in plan) is not particularly limited, but is preferably 50 to 90%, and further 70. It is preferable that it is -85%.
In the present invention, the coating amount of the aqueous coating solution in the layer forming step using the aqueous coating solution is not particularly limited, but the solid content is preferably 0.1 to ² g / m ² .

In the present invention, although not particularly limited, it is preferable that a register mark for alignment is further provided on the plate surface in the plate cylinder. The register mark is a cross-shaped mark provided for alignment in processing such as cutting. Since the register mark is provided on the printing plate, the position of the printing plate can be easily grasped. For example, when a scratch is repaired on the printing plate, the position of the scratch is easily specified. can do.
The register mark is preferably provided at a position closer to the end of the plate cylinder than a region where the concave ink supply portion is formed on the plate surface of the plate cylinder.

  The method for producing the plate cylinder used in the present invention is not particularly limited as long as it is a method capable of forming the concave ink supply part on the plate surface of the plate cylinder, and a known production method can be used as appropriate. It can be manufactured by a corrosion method, electronic engraving, or the like.

(Water-based coating solution)
The aqueous coating liquid used in the present invention contains at least a binder and water, and components may be appropriately added according to each layer to be formed.
In the present invention, “aqueous” means that the main component of the solvent is water. Specifically, it means that 30% or more of the entire solvent is water. The aqueous coating liquid used in the present invention may contain an organic solvent such as alcohol in addition to water as a solvent, but it is preferable that the amount of water is large, and 50% or more of the total solvent is water. .

  Examples of organic solvents that may be contained in addition to water include alcohols such as methanol, ethanol, isopropanol and n-propanol; glycols such as ethylene glycol, diethylene glycol and glycerin; esters such as ethyl acetate and propyl acetate Ketones such as acetone and methyl ethyl ketone; amides such as N, N-dimethylformamide and the like.

  The binder is not particularly limited as long as it can be dissolved or dispersed in an aqueous solvent, and conventionally known water-soluble resins, water-soluble polymers, aqueous resins, and the like can be used. For example, water-soluble resins and water-soluble polymers include polyvinyl pyrrolidone, polyvinyl alcohol, hydroethyl cellulose, carboxymethyl cellulose, phenol resin, polyester, polyacrylic acid, polyacrylic acid ester, polyacrylic acid ester copolymer, polymethacrylic acid copolymer. Examples thereof include water-soluble acrylic resins such as acids, gelatin, starch, casein, and modified products thereof. Water-based resins are vinyl chloride resin emulsions, vinyl chloride-vinyl acetate resin emulsions, vinyl chloride resin emulsions such as vinyl chloride-acrylic resin emulsions, acrylic resin emulsions, urethane resin emulsions, PVC resin dispersions, and acrylic resin dispersions. Examples include a solvent in which a part of the solvent is composed of water, such as John and urethane resin dispersions. The water-based resin can be formed, for example, by dispersing and preparing a solution containing a solvent-based resin with a homogenizer. These may be used individually by 1 type, and may mix and use 2 or more types.

The water-based coating liquid is appropriately selected in accordance with each layer to be formed, and other components are added to the binder and water-based solvent. For example, in the case of a transferable colored layer, a pigment or a dye is further added. Further, a sublimation dye is further added to the dye layer of the sublimation transfer system.
In addition, the aqueous coating liquid used to form each layer further contains various additives such as a mold release agent, a silane coupling agent, organic fine particles such as wax, and inorganic fine particles as necessary. May be.
As the release agent, for example, a releasable graft copolymer can be used. The releasable graft copolymer has at least one releasable segment selected from a polysiloxane segment, a fluorocarbon segment, a fluorinated hydrocarbon segment, and a long-chain alkyl segment as a polymer main chain constituting the resin binder. Is obtained by graft polymerization. Among these, the releasable graft copolymer is preferably a graft copolymer obtained by grafting a polysiloxane segment to a main chain composed of polyvinyl acetal.
Examples of the wax include natural wax such as beeswax, wood wax, rice bran wax and carnauba wax, petroleum wax such as paraffin wax, synthetic wax such as ester wax and polyethylene wax. The wax is not particularly limited, but can be suitably used in combination with polyester as a binder.

  In the aqueous coating solution, the total content of the solvent containing water as a main component may be appropriately selected, but it is usually preferably 70 to 99% by mass of the entire aqueous coating solution, and more preferably 85 to 85%. It is preferably 95% by mass.

In the present invention, the water-based coating liquid may be one having a viscosity of 30 seconds or less as measured by a Zahn cup (manufactured by Toyo Seiki Co., Ltd., No. 2) under more preferable conditions. Can be used for 25 seconds or less. In the production method according to the present invention, even such a low-viscosity coating liquid suppresses the climbing onto the doctor blade, suppresses the generation of streaks in the dye layer formed on the thermal transfer sheet, and is uniform. Demonstrate the effect of improving the nature. The viscosity of the aqueous coating solution is preferably 10 seconds or more, more preferably 14 seconds or more, as measured by a Zahn cup (Toyo Seiki Co., No. 2).
The viscosity seconds here are the time from when the Zahn cup (Toyo Seiki Co., Ltd., No. 2) is filled with the coating liquid and the liquid starts to drop until the liquid flow is cut off. The larger the viscosity seconds, the higher the viscosity. In the present invention, the above-described viscosity measurement is a value measured in an environment of 23 ° C. and 60% RH.

Hereinafter, the present invention will be specifically described with reference to examples. These descriptions do not limit the present invention.
[Example 1]
A plurality of concave ink supply portions as shown in FIGS. 3 and 4 were provided on the plate surface of the gravure roll plate cylinder (circumference 600 mm, length 1000 mm) by a corrosion method.
The shape of the concave ink supply part was as follows. In addition, the following value is an average value obtained by measuring 10 concave ink supply units.
Total ratio of four coating liquid flow path portions constituting the outer periphery to the outer periphery of the concave ink supply unit = Da + Db + Dc + Dd / {(Da + Db + Dc + Dd) + (La + Lb + Lc + Ld)} = 42%
Concave ink supply depth: 15 μm
Da, Db, Dc, Dd: 12.5 μm
La, Lb, Lc, Ld: 17.5 μm

Moreover, each component of the following composition was mixed and the aqueous coating liquid was prepared.
(Composition of aqueous coating solution)
-Carnauba wax 15 parts by mass-Carbon black 15 parts by mass-Isopropanol 20 parts by mass-Pure water 50 parts by mass

  In an environment of 23 ° C. and 60% RH, the above aqueous coating solution is filled in a Zahn cup (Toyo Seiki Co., Ltd., ZAHN VISCOSIMETER Cup No. 2). Was measured, and the viscosity was determined to be 20 seconds.

Using the gravure roll plate cylinder provided with the concave ink supply part, the coating amount of the aqueous coating liquid obtained above was applied to a substrate (made of polyethylene terephthalate, thickness: 4.5 μm) 2.0 g / The thermal transfer sheet of Example 1 was manufactured by coating so as to be m ² (solid content).

[Example 2]
In Example 1, the thermal transfer sheet of Example 2 was manufactured in the same manner as in Example 1 except that the plurality of concave ink supply portions provided on the gravure roll plate cylinder were changed as follows.
Total ratio of the four coating liquid flow path portions constituting the outer periphery to the outer periphery of the concave ink supply unit = Da + Db + Dc + Dd / {(Da + Db + Dc + Dd) + (La + Lb + Lc + Ld)} = 50%
Concave ink supply depth: 15 μm
Da, Db, Dc, Dd: 15 μm
La, Lb, Lc, Ld: 15 μm

[Comparative Example 1]
In Example 1, instead of providing the concave ink supply part on the plate surface of the gravure roll plate cylinder (circumference 600 mm, length 1000 mm), it was carried out except that a plurality of cells as shown in FIG. In the same manner as in Example 1, a thermal transfer sheet of Comparative Example 1 was obtained. 7A is a plan view schematically showing the plate surface of the plate cylinder used in Comparative Example 1, and FIG. 7B is an enlarged view of the cell provided on the plate surface shown in FIG. 7A. FIG. In FIG. 7, a black part represents a convex part and a white part represents a concave part. As shown in FIG. 7, there was no flow path between cells provided on the gravure roll copper plate used in Comparative Example 1.

[Evaluation]
The surface of each thermal transfer sheet obtained in Examples 1 and 2 and Comparative Example 1 was visually observed, and the occurrence of streaks was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.
[Evaluation criteria]
A: No streak was generated.
B: A plurality of streaks occurred and there was a problem in quality.

DESCRIPTION OF SYMBOLS 10 Thermal transfer sheet 1 Base material 2 Release layer 3 Transferable protective layer 4 Transferable coloring layer 5 Transferable adhesive layer 6 Back surface layer 20 Thermal transfer sheet 21 Dye primer layer 22 Dye layer 23 Back surface layer 30 Plate surface 31 (31a, 31b) Concave ink Supply part 32 (32a-32h) Convex wire part 33 (33a-33h) Flow path for coating liquid

Claims (4)

Preparing a substrate;
On one surface of the substrate, an aqueous coating solution containing at least a binder and water is applied by a gravure printing method using a gravure coating apparatus having a plate cylinder in which a plurality of concave ink supply portions are provided on the plate surface. A method of manufacturing a thermal transfer sheet having a step of forming a layer by
The concave ink supply unit in the gravure coating apparatus includes two or more convex wire rods arranged at intervals, and two or more coating liquid channels connecting the concave ink supply units. The total ratio of the two or more coating liquid flow path portions constituting the outer periphery with respect to the outer periphery of the concave ink supply unit is 35 to 55%, Sheet manufacturing method.   2. The thermal transfer sheet according to claim 1, wherein in the plate cylinder, the concave ink supply unit and the coating liquid flow path constitute a concave portion that is continuously opened in the rotation direction of the plate cylinder. Method.   In the plate cylinder, the concave ink supply part is surrounded by a quadrangle between the convex wire part and the coating liquid flow path, and at least one convex wire part is provided at each corner of the quadrangle. The method for producing a thermal transfer sheet according to claim 1, wherein the thermal transfer sheet has a notch portion that is notched, and the coating liquid flow path includes the notch portion.   4. The method for producing a thermal transfer sheet according to claim 1, wherein a register mark for alignment is further provided on the plate surface in the plate cylinder. 5.

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