JP2017209847A - Heat-sensitive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive film in which the wear of a thermal head is suppressed.SOLUTION: There is provided a heat-sensitive film comprising: a base material; a heat-sensitive layer partially provided on at least either surface of the base material; and a protective layer, in which the heat-sensitive layer is color-developing or color-developed by a thermal head. The protective layer is provided on the surface at the side provided with the heat-sensitive layer of the base material in a state where the whole face of the heat-sensitive layer is covered in a contact range between the heat-sensitive film and the thermal head.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heat-sensitive film, and more particularly to a heat-sensitive film that can suppress wear of a thermal head.

  A thermal film is a film in which a thermal coloring composition develops color by a chemical reaction when heated by a thermal head or the like, and a recorded image is obtained. It is used for a wide range of applications as a heat-sensitive recording label of a POS system such as the above (see, for example, Patent Document 1).

  In the thermal recording sheet in which the thermal recording material layer is partially formed on the base sheet while leaving a blank part surrounding the periphery, the entire surface immediately above the thermal recording material layer for the purpose of imparting durability to chemical substances In addition, a heat-sensitive recording sheet is disclosed in which a transparent protective layer is formed on a base sheet so as to cover at least the peripheral portion of the blank portion in the vicinity of the heat-sensitive recording material layer forming portion (see Patent Document 2). However, the formation of a protective layer from the viewpoint of a thermal head has not been studied.

Japanese Patent Laid-Open No. 2002-362027 JP 2005-88557 A

The thermal head has a structure that can selectively generate heat by arranging a plurality of heating resistors in a row. In order to prevent disconnection in contact with the heat sensitive film, the plurality of heating resistors are covered with a head protective layer. In order to increase the heating efficiency of the heating resistor, this head protective layer is usually formed very thin. For this reason, wear of the head protective layer due to contact with the thermal film during printing cannot be avoided, and wear of the head protective layer due to contact with the thermal film has a great influence on the life of the thermal head.
In particular, in order to prevent blocking of the heat sensitive film, when silica or the like is blended in the heat sensitive film substrate as an anti-blocking material, wear of the head protective layer due to contact with the heat sensitive film is remarkable, and the thermal head There was a problem that the lifetime was extremely short.
The present invention has been made paying attention to such a situation, and an object of the present invention is to provide a thermal film in which the wear of the head protective layer of the thermal head is suppressed.

  In order to achieve the above object, the present invention is configured as follows.

  The heat-sensitive film of the present invention is a heat-sensitive film comprising a base material, a heat-sensitive layer partially provided on at least one surface of the base material, and a protective layer. And the said protective layer is provided in the contact range of the said thermal film and the said thermal head in the state which coat | covered the whole surface of the said thermal layer on the surface at the side which provided the said thermal layer of the said base material. .

Moreover, it is preferable that the heat-sensitive film of the present invention includes a plurality of the heat-sensitive layers.
Furthermore, in the heat-sensitive film of the present invention, it is preferable that the base material is a belt-like body, and the protective layer is continuously provided in the length direction of the base material.

  ADVANTAGE OF THE INVENTION According to this invention, the heat sensitive film which can suppress abrasion of a thermal head can be provided.

It is a schematic sectional drawing of the heat-sensitive film of one Embodiment of this invention. It is the figure which looked at the heat-sensitive film of one Embodiment of this invention from the top. It is a schematic sectional drawing showing the state which the thermal head contacted the heat-sensitive film of one Embodiment of this invention. It is a figure which shows the contact range of a heat sensitive film and a thermal head in the heat sensitive film of one Embodiment of this invention. It is a schematic sectional drawing of the heat-sensitive film of other one Embodiment of this invention. It is the figure which looked at the heat-sensitive film of other one Embodiment of this invention from the top. It is a figure which shows the contact range of a heat sensitive film and a thermal head in the heat sensitive film of other one Embodiment of this invention. It is the figure which looked at the heat-sensitive film of another one Embodiment of this invention from the top. It is a figure which shows the contact range of a thermal film and a thermal head in the thermal film of another one Embodiment of this invention.

  The heat-sensitive film of the present invention is a heat-sensitive film comprising a base material, a heat-sensitive layer partially provided on at least one surface of the base material, and a protective layer. And the said protective layer is provided in the contact range of the said thermal film and the said thermal head in the state which coat | covered the whole surface of the said thermal layer on the surface at the side which provided the said thermal layer of the said base material. .

  The heat-sensitive layer is partially provided on at least one surface of the substrate. Here, “partially” means that at least one surface of the substrate is covered with 100% (all) of the heat-sensitive layer. The state that is not.

  The “contact range between the thermal film and the thermal head” means that the thermal film is already in contact with the thermal head in the process of coloring the thermal film with heat from the thermal head, and in the future it will be in contact with the thermal head. Range.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, the schematic sectional drawing of the heat-sensitive film 1 of one Embodiment of this invention is shown. The heat-sensitive film 1 has a structure in which a heat-sensitive layer 3 containing a heat-sensitive coloring composition that develops color by heating and a protective layer 4 are laminated on a film-like substrate 2. As shown in FIG. 1, the heat-sensitive layer 3 is partially formed on the substrate 2 with a width narrower than that of the substrate 2. The protective layer 4 covers the heat-sensitive layer 3 and is formed on the portion of the substrate 2 where the heat-sensitive layer 3 is not formed, at least with the thermal head contact width L shown in FIG. . The width of the protective layer 4 is preferably L or more.

  Further explaining in FIG. 2, in the heat-sensitive film 1, one heat-sensitive layer 3 continuously on the base material 2 in the length direction of the base material 2 has a width narrower than the width of the base material 2. Are formed continuously in the longitudinal direction. The protective layer 4 is continuously formed on the base material 2 in the length direction of the base material 2 with a width equal to or larger than the thermal head contact width L, and covers the entire heat sensitive layer 3. It is directly formed on the base material 2 where there is no part.

The widths L ₁ and L ₂ from the both ends of the thermal head contact width L to the both ends in the width direction of the protective layer 4 shown in FIG. 2 are each preferably preferably 1 mm or more, more preferably 5 mm or more. More preferably, it is 10 mm or more. The upper limit of L ₁ and L ₂ is, for example, about 15 mm. In this specification, the longitudinal direction of the substrate is referred to as “length direction”, and the direction perpendicular to the longitudinal direction on the substrate is referred to as “width direction”.

  As shown in FIG. 3, in the printing process of the thermal film 1, the thermal head 5 comes into contact with the protective layer 4. The thermal head 5 continues to contact the protective layer 4 with the thermal head contact width L as the thermal film 1 moves in the length direction from the rear side to the front side of the paper, thereby coloring the thermal layer. . The thermal head contact width L is the width of the thermal head 5.

  As described above, with the thermal head 5 in contact with the protective layer 4, the thermal film 1 moves in the direction indicated by the arrow in FIG. 4. Therefore, the thermal film 1 and the thermal head 5 are in contact with each other in a range continuous in the length direction of the substrate 2 with the thermal head contact width L. The contact range between the thermal film 1 and the thermal head 5 is the range indicated by reference numeral 6 in FIG.

  As the base material 2, a transparent synthetic resin film, for example, a polypropylene film, a polyethylene terephthalate film, a polystyrene film, a polycarbonate film, etc. can be used. Two or more substrates may be laminated and used as a composite substrate. By using these films, a heat-sensitive film having higher transparency can be produced.

  The thickness of such a film is not particularly limited, but for example, about 10 μm to 100 μm is excellent in coating property and transparency, and is more preferable. These films may have tackiness. In this case, in order to prevent wrinkles and conveyance errors, a blocking agent may be kneaded and formed. As the blocking agent, fine silica powder or the like can be used.

  Moreover, as the base material 2, if transparency is unnecessary, you may use paper, a pulp, etc.

  The base material 2 to which the blocking agent is added and the paper and pulp used as the base material 2 have irregularities on the surface, and if these come into direct contact with the thermal head 5, the thermal head 5 is worn.

  The material forming the heat-sensitive layer 3 includes a heat-sensitive coloring composition containing a dye and a developer. The dye is preferably a color former that develops color when heated. The thermosensitive coloring composition may further contain a filler, a binder, a lubricant, and the like.

  Specific examples of the dye include 2-aniline-3methyl-6- (N-methyl-P-toluidino) fluorane as a leuco dye that is a color former. The content of the dye is preferably 10 to 20% by mass, and more preferably 15 to 18% by mass in the thermosensitive coloring composition.

  Examples of the developer include 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone. The content of the developer is preferably 20 to 45% by mass, more preferably 30 to 40% by mass in the thermosensitive coloring composition.

  As said filler, a kaolin, a calcium carbonate etc. can be mentioned, for example, It is preferable that those particle diameters are 1.0 micrometer or less.

  Examples of the binder include a styrene-butadiene copolymer.

  Examples of the lubricant include polyethylene, zinc stearate, paraffin and the like, and the particle diameter thereof is preferably 0.5 μm or less.

  In order to improve transparency, it is particularly effective to contain paraffin, and this paraffin is a low melting point paraffin having a temperature lower than the coloring temperature of the heat-sensitive layer 3, preferably less than 80 ° C., more preferably less than 50 ° C. Is preferred.

The particle diameter of the low melting point paraffin is preferably 0.5 μm or less as described above. The content of this paraffin is preferably 0.1 to 1.0 g / m ² by dry weight.

  By containing the low melting point paraffin in this way, when the coating solution for forming the heat sensitive layer is applied onto the substrate 2 and dried, the paraffin is melted and the surface of the particles constituting the heat sensitive layer 3 is coated. By entering the gaps such as irregularities and filling the gaps, the irregular reflection on the particle surface can be suppressed and the transparency can be further improved.

  A film in which the heat-sensitive layer 3 is formed on the substrate 2 may have tackiness. In this case, the blocking agent may be added to the surface in order to prevent wrinkles and transport errors.

  When the heat-sensitive layer 3 contains kaolin, calcium carbonate or the like as a filler, or when a blocking agent is added to the film surface on which the heat-sensitive layer 3 is formed on the substrate 2, the surface has irregularities. If these are in direct contact with the thermal head 5, the thermal head 5 is likely to be worn.

  The protective layer 4 protects the surface roughness of the substrate 2 and the heat-sensitive layer 3 and a material having high hardness, suppresses friction with the thermal head 5, and suppresses wear of the thermal head 5. Preferably, the matching of the thermal film 1 to the thermal head 5 is improved so that the color of the thermal layer 3 is smoothly performed. As the protective layer 4, a binder added with a filler, a lubricant, a crosslinking agent and the like is used.

  As resin which is a binder, an acrylic resin etc. are mentioned, for example.

  Examples of the lubricant include polyethylene and zinc stearate.

  Examples of the crosslinking agent include zirconium carbonate.

  Examples of the filler include colloidal silica, calcium carbonate, polymethyl methacrylate (PMMA), and polystyrene (PS).

  The particle diameter of these fillers is preferably 1.0 μm or less.

  In order to further improve the transparency, colloidal silica having a small particle diameter is preferable as the filler.

  The thickness of the heat-sensitive layer 3 and the protective layer 4 formed of the materials as described above, that is, the thickness of the film-like heat-sensitive film 1 excluding the substrate 2 is not particularly limited, but is 1.0 μm or more. The opacity of the heat sensitive film 1 is preferably 10% or less. This opacity is based on JISP8138, a standard for measuring paper opacity.

  In the heat sensitive film 1, an intermediate layer having a barrier property against water or oil may be provided between the heat sensitive layer 3 and the protective layer 4.

  The intermediate layer is mainly formed of a resin. Examples of the resin for the intermediate layer include an acrylic resin emulsion, a water-soluble resin such as a polyvinyl alcohol (PVA) resin, and an SBR resin.

  In order to improve transparency, the resin is a resin having a water-soluble portion, for example, a polyvinyl alcohol (PVA) resin which is a resin having a hydroxy group as a hydrophilic structural unit, or a hydrophobic core particle. A core-shell structure resin coated with a water-soluble shell polymer, for example, a core-shell type acrylic resin is preferred.

  Water-soluble polyvinyl alcohol (PVA) and core-shell type acrylic resins have good film-forming properties, and are water-soluble when a coating liquid for forming an intermediate layer is applied onto the heat-sensitive layer 3 and dried. Since the resin having a portion soaks into the heat-sensitive layer 3 to form a smooth intermediate layer, irregular reflection at the heat-sensitive layer 3 is suppressed, and the transparency is further improved.

  The core-shell type resin is conventionally known. For example, examples of the core-shell type acrylic resin include those commercially available under the name Barrier Star (Mitsui Chemicals).

  In the method for producing the heat-sensitive film 1 of the embodiment, in the heat-sensitive layer forming step, the heat-sensitive layer 3 is formed by partially applying the heat-sensitive layer-forming coating material on the substrate 2. Subsequently, in the protective layer forming step, the protective layer 4 is formed by applying a protective layer-forming coating material on the heat-sensitive layer 3 and on the substrate 2 on which the heat-sensitive layer 3 is not formed.

  When an intermediate layer is provided on the heat sensitive layer 3, the intermediate layer is formed by applying the intermediate layer forming coating liquid on the heat sensitive layer 3 formed in the heat sensitive layer forming step, and then drying the protective layer. In the forming step, the protective layer 4 is formed by applying a protective layer-forming coating material on the intermediate layer and on the heat-sensitive layer 3 and the substrate 2 on which the intermediate layer is not formed.

Modification 1
In FIG. 5, the schematic sectional drawing of the heat-sensitive film 10 of other one Embodiment of this invention is shown. The heat-sensitive film 10 has a structure in which two heat-sensitive layers 13 containing a heat-sensitive color forming composition that develops color by heating and a protective layer 14 are laminated on a film-like substrate 12. The two heat sensitive layers 13 are partially formed on the substrate 12. The protective layer 14 covers the two heat-sensitive layers 13 on the base material 12 and is further on the base material 12 where there is no heat-sensitive layer 13 and has a width equal to or larger than the thermal head contact width L shown in FIG. It is formed with.

  The preferred materials and film thicknesses of the base material 12, the heat sensitive layer 13, and the protective layer 14 are the same as those of the base material 2, the heat sensitive layer 3, and the protective layer 4. An intermediate layer may be formed between the heat sensitive layer 13 and the protective layer 14. The material and thickness of the intermediate layer are the same as those of the intermediate layer that may be preferably formed on the heat-sensitive film 1.

  The two heat sensitive layers 13 may be, for example, a red color heat sensitive layer and a black color heat sensitive layer. The two heat sensitive layers 13 can be colored simultaneously with one thermal head.

  Further explaining with reference to FIG. 6, in the heat-sensitive film 10, two heat-sensitive layers 13 are partially formed on the base material 12 in succession in the length direction of the base material 12. The protective layer 14 is continuously formed on the base material 12 in the length direction of the base material 12 with a width equal to or larger than the thermal head contact width L, covers the two heat sensitive layers 13, and further the heat sensitive layer 13. It is directly formed on the base material 12 in a portion without any gap.

The widths L ₁ and L ₂ from both ends of the thermal head contact width L shown in FIG. 6 to both ends in the width direction of the protective layer 14 are each independently preferably 1 mm or more, more preferably 5 mm or more. More preferably, it is 10 mm or more. The upper limit of L ₁ and L ₂ is, for example, about 15 mm.

  As described above, the thermal film 10 moves in the direction indicated by the arrow in FIG. 7 with the thermal head in contact with the protective layer 14. Therefore, the thermal film 10 and the thermal head are in contact with each other in a range continuous in the length direction of the substrate 12 with the thermal head contact width L. The contact range between the thermal film 10 and the thermal head is the range indicated by reference numeral 16 in FIG.

Modification 2
As shown in FIG. 8, in the heat-sensitive film 20, a plurality of heat-sensitive layers 23 are partially formed in an island shape on a base material 22. The protective layer 24 covers all of the plurality of heat-sensitive layers 23 on the base material 22, and also maintains the width of the contact range with the thermal head on the base material 22 where there is no heat-sensitive layer 23. 22 is formed continuously in the length direction of 22, covers a plurality of island-like heat-sensitive layers 23, and is directly formed on a portion of the base material 22 where there is no heat-sensitive layer 23.

The widths L ₁ and L ₂ from both ends of the thermal head contact width L shown in FIG. 8 to both ends in the width direction of the protective layer 24 are independently preferably 1 mm or more, more preferably 5 mm or more. More preferably, it is 10 mm or more. The upper limit of L ₁ and L ₂ is, for example, about 15 mm.

  The materials and thicknesses of the base material 22, the heat sensitive layer 23, and the protective layer 24 are the same as those of the base material 2, the heat sensitive layer 3, and the protective layer 4. Further, an intermediate layer may be formed between the heat sensitive layer 23 and the protective layer 24. The material and thickness of the intermediate layer are the same as those of the intermediate layer that may be preferably formed on the heat-sensitive film 1.

  The plurality of island-like heat-sensitive layers 23 may be heat-sensitive layers that generate different colors, for example. These thermal layers 23 can be colored simultaneously with one thermal head.

  As described above, the thermal film 20 moves in the direction indicated by the arrow in FIG. 9 with the thermal head in contact with the protective layer 24. Accordingly, the thermal film 20 and the thermal head are in contact with each other in a range continuous in the length direction of the substrate 22 with the thermal head contact width L. The contact range between the thermal film 20 and the thermal head is the range indicated by reference numeral 26 in FIG.

  Next, based on an Example, this invention is demonstrated still in detail. In the following, “part” means “part by mass”.

Example 1
As the substrate, an OPP (biaxially oriented polypropylene) film having a thickness of 40 μm was used.

  The opacity of this OPP film based on JISP8138 was 2.0%.

  The opacity was measured using a reflectometer “TC-6DS / A type” manufactured by Tokyo Denshoku.

[Formation of heat-sensitive layer]
On this OPP film, a coating solution for forming a heat-sensitive layer containing a color former, a developer, a filler, a binder, a lubricant and the like that develops color when heated is applied in a dry weight of 4.0 g / m. to obtain a heat-sensitive layer by performing a coated and dried to be ^2. As shown in FIG. 1, the heat-sensitive layer was continuously formed in the length direction of the base material, and one heat-sensitive layer was partially formed on the base material with a width narrower than that of the base material.

[Formation of intermediate layer]
A coating for forming an intermediate layer composed of a core-shell type acrylic resin was applied on the heat-sensitive layer so that the coating amount was 2.0 g / m ² by dry weight, and then dried. An intermediate layer was formed on the heat sensitive layer.

[Formation of protective layer]
A general-purpose protective layer-forming coating comprising 11 parts of polyethylene, 4 parts of zinc stearate, 46 parts of acrylic, 6 parts of Zr carbonate, and 43 parts of colloidal silica is not formed on the above heat-sensitive layer and intermediate layer. The coating was applied in the contact range with the thermal head on the base material layer so that the coating amount was 4.0 g / m ² in terms of dry weight, followed by drying to form a protective layer to obtain a heat sensitive film.

  The thermosensitive film was set in a thermal printer having a thermal head and color printed. One thermal head could print a heat sensitive film having a length of 100 km.

Example 2
As an example corresponding to the modified example 1, as shown in FIGS. 5 and 6, the heat-sensitive layer is continuous in the length direction of the base material, and the two heat-sensitive layers are narrower than the width of the base material. A heat-sensitive film was obtained in the same manner as in Example 1 except that the film was partially formed with 2 lines on the substrate.

  The thermosensitive film was set in a thermal printer having a thermal head and color printed. One thermal head could print a heat sensitive film having a length of 100 km.

Example 3
As an example corresponding to the modified example 2, a thermosensitive film was obtained in the same manner as in the example 1 except that the thermosensitive layer was partially formed on the base material in an island shape as shown in FIG. .

  The thermosensitive film was set in a thermal printer having a thermal head and color printed. One thermal head could print a heat sensitive film having a length of 100 km.

Comparative Example A thermosensitive film was obtained in the same manner as in Example 1 except that the protective layer was provided with the same width as the thermosensitive layer.

  The thermosensitive film was set in a thermal printer having a thermal head and color printed. When a thermal film having a length of 1 km was printed, the thermal head was worn and printing became impossible.

  As shown in Examples 1 to 3 and Comparative Example, the protective layer is in contact with the thermal film and the thermal head in a state where the entire surface of the thermal layer is coated on the surface of the base on which the thermal layer is provided. By providing in the range, the wear of the thermal head could be suppressed, and a thermal film of several hundred km could be printed with one thermal head.

1, 10, 20 Thermal film 2, 12, 22 Base material 3, 13, 23 Thermal layer 4, 14, 24 Protective layer 5 Thermal head 6, 16, 26 Contact range of thermal film and thermal head

Claims (3)

A heat-sensitive film comprising a base material and a heat-sensitive layer and a protective layer partially provided on at least one surface of the base material, and developing the heat-sensitive layer with a thermal head, or developing a heat-sensitive film,
A heat-sensitive film in which the protective layer is provided in a contact range between the heat-sensitive film and the thermal head in a state where the entire surface of the heat-sensitive layer is coated on the surface of the base on which the heat-sensitive layer is provided. A plurality of the heat-sensitive layers;
The heat-sensitive film according to claim 1. The substrate is a strip;
The protective layer was provided continuously in the length direction of the base material,
The heat-sensitive film according to claim 1 or 2.

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