JP2006347052A - Thermal recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal recording material which has high design properties with a pearl tone and a feel of gloss and which is made free from coloring nonuniformity in a low-energy printing part and has an excellent quality, in regard to the thermal recording material utilizing a thermal coloring method. <P>SOLUTION: In a manufacturing method of the thermal recording material 1 having a thermal coloring layer 3 provided on a substrate 2 and a pattern printing layer 4 provided on the thermal coloring layer 3, the pattern printing layer 4 is printed by using ink containing a pearl pigment or a metal pigment. On the occasion, the portion 5 of the edge of the pattern printing layer 4 is formed by an intaglio of which the cell capacity per a unit area of the portion of the edge of the pattern printing layer 4 is made smaller than that of the portion of this layer except the edge thereof so that an ink transfer amount in the portion 5 of the edge of the layer 4 be reduced in comparison with the ink transfer amount in the portion 6 except the edge. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a heat-sensitive recording material using a heat-sensitive color development method, which is a color-added heat-sensitive recording material that develops colors in different colors and has a pattern printed on the upper layer of the heat-sensitive color-developing layer to improve design. The present invention relates to a high-quality heat-sensitive recording material that does not cause uneven color development.

  Thermosensitive recording materials are used in a wide range of fields such as facsimiles, printers, POS label machines, slips, boarding tickets, commuter passes, etc., since the recording device is simple and easy to maintain and there is no noise. As uses diversify, a multicolor thermosensitive recording material capable of producing multiple colors only by the difference in energy applied by a thermal printer is desired. In particular, as disclosed in Patent Document 1, a color-added multicolor thermosensitive recording material that develops a color mixture at low temperature and mixed color at high temperature heating has high practicality, and many proposals have been made to improve mutual color separation. ing.

  The heat-sensitive recording material is subjected to pattern printing on the upper part of the heat-sensitive color developing layer in order to improve its design and prevent counterfeiting. For example, Patent Document 2 discloses that a light coherent reflective layer mixed with a pearl pigment is formed by gravure printing in order to prevent forgery. Thus, when a pearl-like design is used, pattern printing is performed by gravure printing or silk printing in order to give a glossy feeling.

However, in order to perform gravure pattern printing, the pearl pigment is included to emphasize the pearl tone on the base material, the viscosity is higher than usual, and the ink with high surface tension is used for drying. The thickness of the subsequent printed surface is not uniform, and the edges are likely to rise. At this time, there is a problem that heat from the printer is temporarily difficult to be transmitted due to a step due to the thickness of the pattern printing portion, and unevenness occurs in color development of the low energy printing portion. Such unevenness of color development of the printing becomes unclear printing recording and may become a serious defect. By reducing the printing thickness of the ink containing the pearl pigment, it is conceivable to reduce the above-mentioned uneven color development of printing, but this makes the pearl tone and glossiness poor, and the commercial value is lowered. Thus, the present condition is that the method which can solve said problem has not been found yet.
Japanese Patent Laid-Open No. 54-088135 JP-A-9-169161

  Therefore, the present invention provides a thermal recording material that uses a thermal coloring method, has a high pearly and glossy design, and does not cause color unevenness in a low-energy printing portion, and has excellent quality. The purpose is to provide material.

  In view of the above situation, diligent research and development has been carried out to arrive at the present invention. That is, the invention according to claim 1 is a thermosensitive recording material in which a thermosensitive coloring layer is provided on a support, and a pattern printing layer is provided on the thermosensitive coloring layer, the pattern printing layer being a pearl pigment or a metal pigment. And the ink transfer amount at the edge portion of the pattern printing layer is reduced as compared with the ink transfer amount at the portion excluding the edge. According to a second aspect of the present invention, in the heat-sensitive recording material according to the first aspect, a high-temperature color-developing layer and a low-temperature color-developing layer are sequentially laminated on the support as a heat-sensitive color-developing layer. Material.

  The heat-sensitive recording material according to claim 2, wherein the low-temperature color developing layer develops a red color. 4. The heat-sensitive recording material according to claim 2, wherein the high-temperature coloring layer develops a black color. Further, the invention according to claim 5 is characterized in that an intermediate layer is provided between either the high temperature coloring layer and the low temperature coloring layer, between the low temperature coloring layer and the pattern printing layer, or both. The heat-sensitive recording material according to claim 2.

  According to a sixth aspect of the present invention, in the method for producing a thermosensitive recording material in which a thermosensitive coloring layer is provided on a support and a pattern printing layer is provided on the thermosensitive coloring layer, the pattern printing layer is formed of a pearl pigment or a metal. When printing using pigment-containing ink, the edge of the pattern printing layer is reduced so that the amount of ink transfer at the edge of the pattern printing layer is reduced compared to the amount of ink transfer at the edge of the pattern printing layer. Is formed by an intaglio in which the cell volume per unit area of the edge portion of the pattern printing layer is smaller than the cell volume per unit area of the portion excluding the edge of the pattern printing layer. .

  In the present invention, in a method for producing a heat-sensitive recording material in which a thermosensitive coloring layer is provided on a support and a pattern printing layer is provided on the thermosensitive coloring layer, the pattern printing layer is an ink containing a pearl pigment or a metal pigment. When printing using the pattern printing layer, the edge portion of the pattern printing layer is reduced so that the ink transfer amount at the edge portion of the pattern printing layer is reduced compared with the ink transfer amount at the portion excluding the edge. In this manufacturing method, the cell volume per unit area of the edge portion of the printing layer is formed by the intaglio in which the cell volume per unit area of the portion excluding the edge of the pattern printing layer is reduced. In the heat-sensitive recording material thus produced, the ink transfer amount at the edge portion of the pattern printing layer is reduced compared with the ink transfer amount at the portion excluding the edge, and the edge portion of the pattern printing layer is reduced. In other words, it was a blur-processed product, and there was no color unevenness in the low-energy printed part, and a heat-sensitive recording material having a high pearly and glossy design and excellent quality was obtained. .

  FIG. 1 is a schematic cross-sectional view showing one embodiment of the thermosensitive recording material 1 of the present invention. A thermosensitive coloring layer 3 is provided on a support 2, and a pattern printing layer 4 is further formed on the thermosensitive coloring layer 3. The ink transfer amount of the edge portion 5 of the pattern printing layer 4 is reduced in a step shape as compared with the ink transfer amount of the portion 6 excluding the edge. The heat-sensitive recording material 1 in FIG. 1 is a single-color recording by the color hue of the heat-sensitive color developing layer 3, but the position where the pattern print layer 4 is located on the heat-sensitive color developing layer 3 depending on whether or not the pattern print layer 4 exists ( In A), the colored portion can be observed in a state where, for example, the pearl tone of the pattern printing layer 4 is transmitted, and the original coloring of the coloring portion is observed at the position (B) where the pattern printing layer 4 is not present. Therefore, in the case of FIG. 1, the two color development portions of the thermosensitive recording material 1 are observed as described above.

  FIG. 2 is a schematic cross-sectional view showing another embodiment of the thermosensitive recording material 1 of the present invention. On the support 2, a high temperature coloring layer 7, an intermediate layer 9, a low temperature coloring layer 8, an intermediate layer 10, and a pattern are shown. The print layer 4 and the protective layer 11 are sequentially laminated. This heat-sensitive recording material 1 is a multi-color type heat-sensitive recording material using two kinds of high-temperature color-forming layers 7 and low-temperature color-forming layers 8 as heat-sensitive color layers. For example, if the high-temperature color developing layer 7 uses a material that develops a black color by heating recording, and the low-temperature color developing layer 8 uses a material that develops a red color by heating recording, the heating temperature at the time of recording is adjusted to perform high-temperature heating. The black color can be developed with red, and the red color can be developed with low temperature heating, and the red and black color can be developed with one heat-sensitive recording material.

  The intermediate layer 9 is provided to prevent color mixing between the high temperature coloring layer 7 and the low temperature coloring layer 8, and the intermediate layer 10 prevents the low temperature coloring layer 8 and the pattern printing layer 4 from mixing with each other. In other words, the layers are provided so as to be functionally separated from each other. Further, the protective layer 11 is positioned as the outermost surface on the recording surface of the heat-sensitive recording material 1 and improves durability such as chemical resistance, water resistance, and friction resistance in improving the suitability of the thermal head and handling the heat-sensitive recording material. Etc. can be achieved. In FIG. 2, an intermediate layer is provided between the high-temperature coloring layer and the low-temperature coloring layer, and between the low-temperature coloring layer and the pattern printing layer. However, the effect of color mixing (mixing of the layers) is practical. In the case of a small amount, the intermediate layer is not necessarily required.

  In the heat-sensitive recording material 1 in FIG. 2, the ink transfer amount of the edge portion 5 of the pattern printing layer 4 is reduced in a linear slope as compared with the ink transfer amount of the portion 6 excluding the edge. The way in which the ink transfer amount at the edge portion of the pattern printing layer is reduced compared with the ink transfer amount at the portion excluding the edge is reduced in a stepped shape as shown in FIG. 1 or as shown in FIG. Such a linear decrease, a concave curve or a convex curve, or the shape of the decrease is not limited.

Hereinafter, each layer constituting the heat-sensitive recording material of the present invention will be described in detail.
(Support)
The support 2 in the heat-sensitive recording material of the present invention is made of a sheet-like, film-like or plate-like material, and the material is not particularly limited. Polyethylene terephthalate (PET), nylon, cellulose diacetate, polystyrene, Plastics such as polyethylene, polypropylene, polyester, polyimide, polyvinyl chloride, and polycarbonate, metals such as copper and aluminum, paper, and impregnated paper can be used alone or in combination and laminated. The thickness of the support is suitably about 0.005 to 5 mm.

(Thermosensitive coloring layer)
The heat-sensitive recording material of the present invention has a heat-sensitive coloring layer 3 provided on a support as a portion having a heat-sensitive coloring material that develops color by heating. As the heat-sensitive coloring layer, a low-temperature coloring layer 8 and a high-temperature coloring layer 7 are provided. By being laminated, it is useful as a multicolor thermosensitive recording material. This thermochromic layer contains a thermochromic material, and specifically includes an electron-donating dye precursor and an electron-accepting compound that develop color by a thermal melting reaction, and further, if necessary, a sensitizer and a color fading. Inhibitors, fillers such as pigments and lubricants, dispersants, binders and the like are included.

  The thermosensitive coloring layer is formed as a layer by coating or printing on the support. Examples of the method for forming the thermosensitive coloring layer include gravure, roll coating, spray coating, dipping, and others. As the electron-donating dye precursor, one that is applied to this kind of heat-sensitive material as a leuco dye, one that develops color in yellow, cyan, magenta, or the like is selected. Specific examples of the electron-donating dye precursor include triphenylmethane, fluorane, phenothiazine, auramine, spiropyran, and indinophthalide, and are appropriately selected according to the color to be colored.

  The above-mentioned electron-accepting compound is a developer combined with an electron-donating dye precursor, such as a phenolic substance such as bisphenol A, octylphosphonic acid, nonylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, tetradecyl. Examples thereof include organic acids such as phosphonic acid, octadecylphosphonic acid and erotic tetradecanoic acid, metal complex compounds, thiodiphenylurea, and quinones.

  Examples of the sensitizer include stearic acid amide, behenic acid amide, methylene bis stearic acid amide, dibenzyl oxalate, tolylbiphenyl ether, and fatty acid amides. Examples of the color fading inhibitor include analogs of color developers blocked with hydroxyl groups, organometallic salts such as zinc salts, and hindered phenols. When the pigment is used in combination, the white pigment has an effect of scattering visible light and near infrared light to the surroundings, promotes near infrared light absorption into the light absorbent and increases heat generation efficiency. Examples of the pigment include calcium carbonate, aluminum hydroxide, silicate, zeolite, silica, kaolin clay, and urea formalin resin.

  For the formation of the thermosensitive coloring layer, an ink or a paint is prepared in order to form a layer made of the above materials. As a binder for ink or paint, a water-soluble resin is mainly used, and examples thereof include polyvinyl alcohol, starch, methyl cellulose, hydroxyethyl cellulose, gelatin, casein, urea resin, melanin resin, amide resin, and polyurethane resin. Moreover, various adjuvants can be added as needed.

  In the heat-sensitive recording material of the present invention, for example, it is preferable to use a low-temperature color-forming layer and a high-temperature color-forming layer in units of one sheet under the condition that the heat-sensitive color developing layer has different color hues. The low temperature coloring layer and the high temperature coloring layer have different color development start temperatures. Specifically, the color development start temperature (definition is the temperature at which the thermosensitive color developing layer starts to develop color after 1 second of hot plate pressure bonding) is 50 ° C. or higher and 100 ° C. or higher, respectively. Further, it is desirable that the difference in color development start temperature between the low temperature coloring layer and the high temperature coloring layer is 20 ° C. or more. That is, when the color development start temperature of the low-temperature color development layer is less than 50 ° C., the printing sensitivity is too good, and the color develops when left at a high temperature such as in summer, resulting in poor storage stability. Also, if the color development start temperature of the high temperature color development layer is less than 100 ° C., the color density of the low temperature color development layer cannot be obtained sufficiently, and the high temperature color development layer develops color. It is because it cannot be obtained.

  The high-temperature coloring layer is preferably one that develops a black color such as black, dark brown, dark blue, or deep red. The low temperature coloring layer is preferably one that develops a red color such as red, orange, or reddish purple, and the low temperature coloring layer can be one that develops a light color such as pale blue or pale brown. As described above, the low-temperature coloring layer and the high-temperature coloring layer use heat-sensitive coloring materials having different coloring start temperatures and coloring hues, that is, the above-mentioned electron-donating dye precursor (leuco dye) and developer. Depending on the selection, the conditions of the color development start temperature and the color hue can be changed.

By changing the conditions of the color development start temperature and the color hue, it is possible to produce multiple color hues with a single thermal recording material. As for the hue, the high temperature color development layer develops a black color as described above. The low temperature coloring layer is preferably one that develops a red color. As a heat-sensitive recording material, when a high-temperature coloring layer and a low-temperature coloring layer are laminated, only a low-temperature coloring layer develops color by relatively low-temperature heating recording, and a relatively high-temperature heating recording includes a low-temperature coloring layer. Both the color-developing layer develops color, the color development of the high-temperature color-development layer absorbs the hue of color development of the low-temperature color-development layer, makes it easy to see, and the difference between the color development of the high-temperature color-development layer and the color development of the low-temperature color-development layer Because. The thickness of the thermosensitive coloring layer as described above is not different between the high-temperature coloring layer and the low-temperature coloring layer, and the thickness is about 1.0 to 20 g / m ² when dried.

(Pattern printing layer)
The pattern printing layer 4 in the heat-sensitive recording material of the present invention contains a pearl pigment or a metal pigment, and among the printed portions of the pattern printing layer, the ink transfer amount at the edge portion is the ink at the portion excluding the edge. It is characterized by a decrease compared to the amount of transfer. The ink for forming the pattern printing layer is a solution in which components mainly composed of a pearl pigment or metal pigment colorant and a binder are dissolved or dispersed in a solvent, and if necessary, other pigments, dyes, various surfactants Conventional additives such as agents, lubricants, antifoaming agents and leveling agents may be appropriately selected and blended. The ink for pattern printing layer adjusted in this way can be printed by the intaglio system represented by gravure printing, and a pattern printing layer can be formed. The pearl pigment in the ink includes natural products such as fish scale foil, basic lead carbonate, bismuth oxychloride, natural mica (mica) coated with metal oxide, and synthetic mica surface coated with metal oxide. And synthetic products such as those coated with In general, from the viewpoints of availability and safety, those obtained by coating the surface of natural mica with a metal oxide and those obtained by coating the surface of synthetic mica with a metal oxide can be preferably used.

  The pearl pigment is a pigment having both a specular gloss and a pearl gloss other than the color tone, and the color tone mainly depends on the type of the metal oxide coated on the surface. For example, those using titanium oxide or aluminum oxide as the metal oxide can obtain a silver-white color tone, and those using iron oxide or those provided with a titanium oxide film and an iron oxide film must be iron oxide. Gold, red, and copper color tones are obtained by absorption in a partial wavelength region by the coating. In addition, those coated with chromium oxide or cobalt titanate can obtain a green color tone. The specular gloss of pearl pigment is due to the difference in the refractive index of each layer at each boundary between the metal oxide layer with a high refractive index, the mica layer with a low refractive index, and the medium around the pearl pigment. Obtained by reflection.

  The pearly luster of the pearl pigment is such that each boundary surface within one unit of the pearl pigment is parallel and the reflected light is combined. For example, the reflected light from the alternately layered surfaces of the calcium carbonate layer and the protein layer of the pearl Obtained by doing the same regular multiple reflection. Examples of commercially available pearl pigments include Iriodin 100 (particle diameter 10-60 μm, silver), 103 (same 10-50 μm, silver), 300 (same 10-60 μm, gold), 302 (same 5-5). 20 μm, gold), 323 (5-20 μm, gold), 504 (10-60 μm, red), 524 (5-20 μm, red), 502 (10-60 μm, copper color), 520 (5 to 20 μm, copper color), GP (10 to 40 μm, green) (Merck Japan Co., Ltd.), ULTIMICA SB-100 (5 to 30 μm, silver), SD- 100 (10-60 μm, silver), RYB-100 (5-30 μm, gold), RYD-100 (10-60 μm, gold) (manufactured by Nippon Koken Kogyo Co., Ltd.), TAYCA PEARL TP-500 (same 10 to 70 μm, silver), TPX-720 (seven 7 to 45 μm, silver) (above, manufactured by Teika Co., Ltd.) and the like. Pearl pigments may be used alone or in combination of two or more.

  In the case of a pearl pigment, gloss is generated due to regular multiple reflection on parallel surfaces having different refractive indexes. Therefore, when the particle diameter of the pearl pigment is smaller than 5 μm, the gloss is lowered. Therefore, the particle diameter is preferably 5 μm or more. The particle diameter of the pearl pigment is desirably 100 μm or less. This is because if the particle diameter of the pearl pigment is too large, the concealing property becomes high, and the color recording of the thermosensitive coloring layer located under the pattern printing layer becomes unreadable for practical use of the thermosensitive recording material. The particle diameters of the pigments in the present invention all mean the average particle diameter.

  Moreover, a metal pigment can be used as a coloring agent in a pattern printing layer. The metal pigments include aluminum powder, brass powder, stainless steel powder, tin powder, zinc powder, bronze powder, nickel powder, copper powder, gold powder, silver powder, mixed powders, and pigments made of these metal alloys. Is mentioned. The particle diameter of the metal pigment is also used in the same range as in the case of the pearl pigment.

  Binders (vehicles) constituting the pattern printing layer include gum rosin, wood rosin, tall oil rosin, lime rosin, rosin sell, maleic acid resin, polyamide resin, vinyl resin, nitrocellulose, cellulose acetate, ethyl cellulose, chlorinated rubber, cyclized rubber An ethylene-vinyl acetate copolymer resin, a urethane resin, a polyester resin, an alkyd resin, a resin mixture such as gilsonite, dammar or shellac, a mixture of the above resins, a water-soluble resin or an aqueous emulsion resin obtained by water-solubilizing the above resin.

  A pattern printing layer ink in which the pearl pigment or metal pigment colorant described above and a component mainly composed of a binder are dissolved or dispersed in a solvent such as hydrocarbons, alcohols, ethers, esters or water. It is adjusted and formed on the thermosensitive coloring layer by intaglio printing in a predetermined pattern. In the present invention, with respect to the intaglio for forming the pattern printing layer, the pattern printing layer is formed so that the ink transfer amount at the edge portion of the pattern printing layer is reduced compared with the ink transfer amount at the portion excluding the edge. Using an intaglio having a shape in which the cell volume per unit area of the edge portion of the pattern printing layer is smaller than the cell volume per unit area of the portion excluding the edge of the pattern printing layer It is.

  As a method for reducing the cell volume of the intaglio plate, a method of changing the depth of the plate while keeping the cell area constant, a method of changing the diameter of the cell while keeping the depth of the plate constant, or a method of using both in combination It does not ask which format it is in. In addition, as the intaglio used, there is a corrosion gravure plate or an electronic engraving gravure plate, whereby the edge of the printed portion as a pattern printing layer is raised, and the color development unevenness of the thermosensitive coloring layer in the low energy printing portion may occur. A pattern printing layer having a uniform thickness can be formed.

  Conventionally, the cause of the rising edge of the pattern printing layer is not clear in detail, but is considered to be due to the following phenomenon. A printed matter (heat-sensitive recording medium) produced using a conventional gravure plate is produced by high-speed rotary printing, and the ink for a pattern printing layer used therefor has viscosity. Then, in the process of transferring the ink to the printing material, a meniscus (liquid surface) is formed so that the ink is dragged out of the cell when the ink is transferred from the plate. In particular, the pattern printing layer in the present invention is a necessary condition for obtaining a high-quality printing surface with uniform meniscus formation and uniform amount of transition when observing the color recording portion of the thermosensitive coloring layer located thereunder. It becomes. However, under high-speed printing conditions, the stress applied to the ink is strong and the meniscus is likely to be unstable, and in particular, the edge portion of the printed portion tends to rise. For this reason, the thickness of the edge of the printed part is larger than the other parts, making it difficult for the heat from the printer to be transmitted temporarily, especially in the case of low-energy printing, causing unevenness in color development in the thermal coloring layer. It is.

  In addition, the portion where the cell volume of the intaglio is reduced, that is, the edge portion of the pattern printing layer, but the cell volume of about 5% to 90% compared to the intaglio cell volume of the portion excluding the edge. It is effective to prevent the generation of a meniscus that grows large at the edge of the pattern printing layer specifically by making the volume. Further, the width of the edge portion of the pattern printing layer as shown by “m” in FIG. 1 is about 0.5 to 5 mm to prevent the edge portion of the pattern printing layer from rising. On the other hand, it is advantageous because it is effective and the outline of the pattern printing layer is not impaired.

Moreover, the thickness in a pattern printing layer is 0.5-10 g / m < ² > at the time of drying as thickness in the part except the edge of the pattern printing layer, Preferably it is 0.5-3 g / m < ² >. However, depending on the type of ink for the pattern printing layer, the pearl tone and glossiness are moderately given, and the pattern printing layer is below the pattern printing layer from the observer who sees the color recording part of the thermal recording material. In order to make the color-developing portion of the heat-sensitive color-developing layer located visible and easy to read, it is formed by adjusting the thickness of the print layer so as not to impair the transparency.

  In the present invention, the edge portion of the pattern printing layer is changed to the edge portion of the pattern printing layer so as to reduce the ink transfer amount of the edge portion of the pattern printing layer compared to the ink transfer amount of the portion excluding the edge. 3 is formed by an intaglio in which the cell volume per unit area is smaller than the cell volume per unit area of the portion excluding the edge of the pattern printing layer. Specifically, the intaglio as shown in FIG. Can be used. That is, as shown in FIG. 3, the cell volume of the plate is set to a regular intaglio portion (an intaglio portion corresponding to a portion excluding the edge of the pattern printing layer) 13 and an intaglio portion of the edge that reduces the amount of ink transfer ( A plate 12 having a reduced volume intaglio part 14 is formed. Thereby, the reduced transition layer 41 at the edge portion of the pattern printing layer 4 can be provided, and the width (m) of the reduced transition layer is as small as 0.5 to 5 mm, so that the product value is not lowered. .

In the present invention, the amount of ink transfer in the pattern printing layer needs to be reduced at the edge of the pattern printing. Further, when the cell arrangement direction is not the same as the printing flow direction but has an inclination, it is desirable to reduce the amount of ink transfer also at the edge portion of the pattern printing layer.

(Middle layer)
The heat-sensitive recording material of the present invention provides a plurality of heat-sensitive color developments by providing the intermediate layer 9 between the low-temperature color-developing layer and the high-temperature color-development layer, or providing the intermediate layer 10 between the low-temperature color-development layer and the pattern printing layer. By separating the layers without directly contacting each other and without directly contacting the thermosensitive coloring layer and the pattern printing layer, it is possible to prevent migration of acidic substances to other coloring layers and mixing of the layers. . Further, by separating the layers, each color tone of the thermosensitive coloring layer and the pattern printing layer is clearly expressed, and the coloring sensitivity of each layer can be adjusted by controlling the thickness between the two layers.

  As the resin constituting the intermediate layer, starches, celluloses, gelatin, casein, polyvinyl alcohols, maleic anhydride copolymers, acrylics, styrene-butadiene copolymer emulsions, urea resins, melamine resins, amide resins, A polyurethane resin etc. are mentioned. The resin as described above and various auxiliary agents as necessary can be added to adjust the ink, and can be formed by known coating methods such as offset printing, letterpress printing, and gravure coating. The intermediate layer is formed so as not to impair the transparency in order to make it easy to distinguish the color developing portion of the thermosensitive color developing layer located below the intermediate layer as viewed from the observer.

The thickness of the intermediate layer is about 0.1 g / m ² or more at the time of drying is preferably 1 to 10 g / m ^2. If the thickness is too small, the function as an intermediate layer will be insufficient, and if it is too thick, the thermal sensitivity of the thermosensitive recording material will be reduced, or the adhesion with the thermosensitive coloring layer will be reduced, which is also disadvantageous in terms of cost. .

(Protective layer)
In the heat-sensitive recording material of the present invention, the protective layer 11 can be provided on the outermost surface side in contact with the thermal head, and improvement in suitability by the thermal head and chemical resistance, water resistance, friction resistance, etc. in handling the heat-sensitive recording material. The durability can be improved. As a material for forming the protective layer, a resin composition having desired physical properties as the surface protective layer is selected. In particular, when surface scratch resistance, chemical resistance, and contamination resistance are required, ultraviolet rays and electron beam curable resins are often used. In addition, in order to make the protective layer suitable for the thermal head, various inorganic fillers and organic fillers are added as slip agents within a range that does not interfere with the transparency of the protective layer, and various waxes, silicone components, fluorine A peelable component such as a system component can also be added. The thickness of the protective layer is selected according to desired physical properties and the like, but is usually 0.1 to 10 g / m ² at the time of drying. The protective layer can also be formed by the same method as the above intermediate layer.

  The above heat-sensitive recording material of the present invention can be applied to various uses such as prepaid cards in general, commuter pass, deposit / save card, credit card, ID card and the like.

  Next, the present invention will be described more specifically with reference to examples. Hereinafter, unless otherwise specified, parts or% is based on mass.

Example 1
Using a 188 μm thick milky white polyethylene terephthalate as a support, printing is performed by gravure printing on one side of the support at the position shown in FIG. A high-temperature coloring layer 7 having a thickness of 5 g / m ² is formed at the time of drying, and subsequently printed on the high-temperature coloring layer by a gravure printing method using an intermediate layer ink having the following composition. An intermediate layer 9 having a thickness of 3 g / m ² is formed, and further printed on the intermediate layer by a gravure printing method using a low-temperature coloring layer ink having the following composition, and a thickness of 5 g / m ² when dried. A low temperature coloring layer 8 was formed.

Further, on the low temperature coloring layer, printing is performed by the gravure printing method using the ink used in the above intermediate layer to form an intermediate layer 10 having a thickness of 3 g / m ² at the time of drying. In order to reduce the amount of ink in the intaglio of 100 line / 25 mm screen, as shown in FIG. 3, using the ink for the pattern printing layer having the following composition, the edge portion of the pattern printing layer of the plate The gravure plate in which the intaglio portion 14 with the reduced amount of ink transfer was prepared so that the cell volume per unit area of the portion corresponding to 2 was 50% with respect to the regular intaglio portion 13 was 100 m / min. Gravure printing was performed at a speed, and as shown in FIG. 2, the pattern printing layer 10 was formed with a dry thickness of 1.5 g / m ² . Further, a protective layer having a thickness of 3 g / m ² was formed on the pattern print layer by printing using a gravure printing method using an ink for a protective layer having the following composition, irradiation with ultraviolet rays, and Example 1 A heat-sensitive recording material was prepared.

(High temperature coloring layer ink) (Coloring start temperature 100 ° C)
Black dye (3- (N-ethyl-N acylamino) -6-methyl-7anilinofluorane)
10 parts Developer (bisphenol A) 85 parts Solvent (polyvinyl alcohol 10% aqueous solution) 5 parts

(Ink for intermediate layer)
Polyvinyl alcohol 10% aqueous solution 95 parts Isocyanate curing agent 5 parts

(Ink for low temperature coloring layer) (Coloring start temperature 80 ° C)
Red dye (3-diethylamino-7-chlorofluorane) 10 parts Developer (3,3-dichlorophenthiourea) 85 parts Solvent (polyvinyl alcohol 10% aqueous solution) 5 parts

(Ink for pattern printing layer)
Vinyl chloride-vinyl acetate copolymer resin (VYLF-X manufactured by Union Carbide)
21 parts Pearl pigment (Iriodin / Afflair 223 manufactured by Merck Japan, particle size 5 to 25 μm) 21 parts Toluene 29 parts Methyl ethyl ketone 29 parts

(Ink for protective layer)
Polyurethane acrylate (prepolymer) 20 parts Dipentaerythritol hexaacrylate 100 parts 2-hydroxyethyl acrylate 5 parts Photopolymerization initiator 1 part Sensitizer 1 part Methyl ethyl ketone 1 part

(Comparative Example 1)
In the heat-sensitive recording material produced in Example 1, a 100 line / 25 mm screen intaglio was used as the plate for forming the pattern printing layer, and the portion per unit area corresponding to the edge portion of the pattern printing layer of the plate was used. The thermal sensitivity of Comparative Example 1 was the same as in Example 1 except that the gravure plate with the cell volume unchanged from the regular intaglio part was subjected to gravure printing at a speed of 100 m / min to form a pattern printing layer. A recording material was prepared.

  When energy was applied to the thermal head for printing on the heat-sensitive recording material obtained in Example 1 above and recorded so that the surface temperature of the thermal head was 100 ° C., red color was developed in the low-temperature coloring layer. In addition, when energy was applied to the thermal head and recording was performed so that the surface temperature of the thermal head was 120 ° C., the high temperature coloring layer was high so as to absorb the red color of the low temperature coloring layer. The color developed with a black density. Both the red coloration and the black coloration described above were records that could be clearly read through the pattern printing layer having a pearl tone. In addition, the printed thermal recording medium of Example 1 has a high design quality with a pearly tone and glossiness, and has excellent quality without causing color unevenness in the low-energy printing portion of the red coloring portion. there were.

  When energy was applied to the thermal head for printing on the heat-sensitive recording material of Comparative Example 1 and recording was performed so that the surface temperature of the thermal head was 100 ° C., red-colored printing was performed in the low-temperature coloring layer. Furthermore, when energy was applied to the thermal head and the recording was performed such that the surface temperature of the thermal head was 120 ° C., the high-temperature coloring layer was colored with a high density of black so as to absorb the red coloring of the low-temperature coloring layer. did. However, uneven coloring occurs in the red coloring portion corresponding to the position below the edge of the pattern printing layer, and the recorded information is difficult to read.

It is a schematic sectional drawing which shows one embodiment of the thermosensitive recording material of this invention. It is a schematic sectional drawing which shows other embodiment of the thermosensitive recording material of this invention. It is the schematic which shows an example of the shape of the intaglio corresponding to the pattern printing layer which has the reduction | decrease transition layer of the thermosensitive recording material of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal recording material 2 Support body 3 Thermosensitive coloring layer 4 Pattern printing layer 5 Edge part of pattern printing layer 6 Part except the edge of pattern printing layer 7 High temperature coloring layer 8 Low temperature coloring layer 9 Intermediate layer 10 Intermediate layer 11 Protective layer 12th edition 13 Regular intaglio part (intaglio part corresponding to the part excluding the edge of the pattern printing layer)
14 Intaglio part of the edge to reduce the transfer amount of ink (intaglio part of reduced volume)
41 Reduced transition layer

Claims (6)

  In a heat-sensitive recording material in which a thermosensitive coloring layer is provided on a support, and a pattern printing layer is provided on the thermosensitive coloring layer, the pattern printing layer contains a pearl pigment or a metal pigment, and an edge of the pattern printing layer The heat-sensitive recording material is characterized in that the amount of ink transferred in the portion is reduced compared to the amount of ink transferred in the portion excluding the edge.   2. The heat-sensitive recording material according to claim 1, wherein a high-temperature coloring layer and a low-temperature coloring layer are sequentially laminated as a heat-sensitive coloring layer on the support.   The heat-sensitive recording material according to claim 2, wherein the low-temperature coloring layer develops a red color.   The heat-sensitive recording material according to claim 2 or 3, wherein the high-temperature coloring layer develops a black color.   5. An intermediate layer is provided between the high temperature coloring layer and the low temperature coloring layer, between the low temperature coloring layer and the pattern printing layer, or both. The heat-sensitive recording material described. In a method for producing a thermosensitive recording material in which a thermosensitive coloring layer is provided on a support, and a pattern printing layer is provided on the thermosensitive coloring layer, the pattern printing layer is formed using an ink containing a pearl pigment or a metal pigment. When printing, the edge portion of the pattern printing layer is reduced to the edge of the pattern printing layer so that the amount of ink transfer at the edge portion of the pattern printing layer is reduced compared to the ink transfer amount of the portion excluding the edge. A method for producing a heat-sensitive recording material, characterized in that the cell volume per unit area of the portion is formed by an intaglio in which the cell volume per unit area of the portion excluding the edge of the pattern printing layer is reduced.

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