JPH11334213A - Thermal transfer recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a clear print on a recording sheet even if a surface of a fluorescent ink layer for forming a thermal transfer ink layer is smoothed and a concentration of a fluorescent pigment in an ink layer is enhanced by specifying a mean particle size of the pigment of the layer. SOLUTION: A thermal transfer ink layer 2 made of a fluorescent pigment, a heat fusible substance and a binder resin is provided on a surface of a base material 1. The layer 2 has a fluorescent ink layer formed of a mixture of the pigment and the binder resin. As the pigment, a mixture of a polymer obtained by emulsion polymerizing it in the presence of a fluorescent dye or a dyed material of the polymer by the fluorescent dye obtained by dyeing the polymer by the dye or an impregnated material is used. A mean particle size of the pigment of mainly 0.1 to 2 μm is used. Thus, transferability, sharpness, small part skip, printing density can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording medium for recording characters and images having a fluorescent color by a thermal transfer recording method.

[0002]

2. Description of the Related Art Conventionally, as a thermal transfer recording medium, a heat-meltable ink containing a coloring agent composed of a dye and / or a pigment on a heat-resistant support such as a polyester film, a wax as a fixing agent, and other additives. Those having a layer are known. A print recording method using such a recording medium is performed by superimposing a recording sheet on the surface of a hot-melt ink layer of a medium, applying a thermal head from the recording medium side, and fusing and transferring the ink layer at that portion onto the recording sheet. ing. Conventionally, these thermal transfer methods have mainly been used for monochrome printing such as facsimile and bar code, but in recent years, demand for color printers using the same method has been increasing.

[0003] Among them, the demand for thermal transfer recording media has been increasing because a special color which cannot be reproduced by an ink jet printing method or electrophotography, that is, a fluorescent color or a gold-silver color can be reproduced. Of these, thermal transfer recording media having a fluorescent color include those in which a fluorescent dye or a fluorescent pigment is added to an ink layer, as described in (A) JP-A-59-54598 and (B) JP-A-63-89384. And (C)
JP-A-63-319189 is known.

[0004] (A) is a heat-sensitive fluorescent transfer medium containing about 10 to 60% by weight of a fluorescent pigment and a hot melt adhesive in a heat-sensitive transfer ink layer used for a heat-sensitive fluorescent recording medium;
(B) includes a fluorescent thermal transfer medium for forming a fluorescent transfer layer on the base film directly or via a release agent layer;
And (C) each describe a heat-sensitive transfer recording sheet provided with a heat-fusible ink layer containing an organic fluorescent pigment and a wax as essential components on a support.

[Problems to be solved by the invention]

[0005] In any of these conventional thermal transfer recording media, a sufficient print density cannot be obtained, and in order to obtain a sufficient print density, it is necessary to contain a large amount of a fluorescent dye or a fluorescent pigment in the ink layer. there were.

Particularly, when a fluorescent dye is used, there is a problem in compatibility with binders forming an ink layer, and when a large amount of the fluorescent dye is used to obtain a sufficient print density, the fluorescent dye may bleed out. This causes adverse effects such as soiling of the thermal head at the time of printing, causing abnormal transfer, and also causes problems such as a decrease in water resistance and solvent resistance of the printed matter.

For this reason, in a thermal transfer ribbon, these fluorescent dyes are generally impregnated in a resin powder in advance and used as a fluorescent pigment. However, since these fluorescent pigments are not sensitive to heat, if a large amount of fluorescent pigment is used to obtain a sufficient print density, the thermal sensitivity of the entire ink layer is reduced and sufficient thermal transferability cannot be obtained. Problem had arisen.

[0008] In the production of fluorescent pigments, resins to be impregnated with fluorescent dyes are mechanically pulverized, so that pulverization of these resins is very difficult, and most of them are 10 μm in particle size.
m, and even a small one was about 3 to 4 μm. On the other hand, the ink layer of the normal ink ribbon has a thickness of 1
When the ink ribbon is manufactured by adding a large amount to such an ink layer, the surface of the ink ribbon is roughened to hinder normal contact with an image receiving paper at the time of printing, thereby deteriorating thermal transferability. Was causing it.

In order to solve the above problems, the present invention uses a fluorescent pigment having a small average particle size (0.1 to 2 μm) to smooth the surface of the ink layer and reduce the concentration of the fluorescent pigment in the ink layer. It is an object of the present invention to provide a thermal transfer recording medium capable of obtaining clear printing on a recording sheet even when the recording medium is increased.

[0010]

According to the present invention, there is provided a thermal transfer recording medium comprising (1) a thermal transfer ink layer having at least a thermal transferable fluorescent ink layer containing a fluorescent pigment on one surface of a substrate. A thermal transfer recording medium characterized in that the fluorescent pigment in the fluorescent ink layer has an average particle size of 0.1 to 2 μm, and (2) the content of the fluorescent pigment in the fluorescent ink layer is 2
0 to 70% by weight of the thermal transfer recording medium according to (1).

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an example of the thermal transfer recording medium of the present invention. In the present invention, the thermal transfer recording medium is configured by providing a thermal transfer ink layer 2 made of a fluorescent pigment, a heat-fusible substance, and a binder resin on the surface of a substrate 1. In addition, on the back surface of the substrate 1, a lubricant is added to the binder resin,
A heat-resistant layer 3 to which a surfactant, inorganic particles, organic particles, a pigment and the like are added can be provided.

The thermal transfer ink layer 2 has at least a fluorescent ink layer formed from a mixture of a fluorescent pigment and a binder resin. The thermal transfer ink layer 2 may be formed only from the fluorescent ink layer 21 or may be formed from two layers, the fluorescent ink layer 21 and the heat bonding ink layer 22, as shown in FIG. Further, as shown in FIG. 3, the thermal transfer ink layer 2 may be formed from three or more layers of the above-described two layers and the primer layer 23. The primer layer is
When the purpose is to separate the ink layer from the base material during printing, as a release layer, as a protective layer when provided to protect the ink layer after printing, and when the purpose is to bond the base material and the ink layer. Can be provided as an adhesive layer. Further, to the fluorescent ink layer 21, an organic / inorganic pigment can be added for hue adjustment as needed, or a dispersant, a leveling agent, an antifoaming agent, an antistatic agent and the like can be added.

As the substrate 1, a substrate film conventionally used for a thermal transfer sheet can be used as it is. Examples of preferable base material 1 include plastics such as polyester, polyethylene, polypropylene, polycarbonate, cellulose acetate, polystyrene, polyvinyl chloride, polyvinylidene chloride, nylon, polyimide, polyvinyl alcohol, fluororesin, chlorinated rubber, and ionomer, and condenser paper. And papers such as paraffin paper, cellophane, cellulose acetate, non-woven fabric, and the like.

The thickness of the substrate 1 can be appropriately changed depending on the material so that the strength and the thermal conductivity become appropriate, but it is preferably 2 to 25 μm.

As the fluorescent pigment, (1) a mixture of a polymer obtained by emulsion polymerization using an emulsifier or a stabilizer in an aqueous or non-aqueous system in the presence of a fluorescent dye and a fluorescent dye, or (2) Examples include a dyed product of a polymer obtained by dyeing an emulsion polymer with a fluorescent dye, or an impregnated product. As the polymer contained in the fluorescent pigments (1) and (2), those having a softening point of 50 to 120 ° C. are used. Examples of the pigment containing the polymer in the above range include “Shinloich Color Base SW-10 Series”, “Shinloich Color Base SP-10 Series”, and “Shinloich Color Base 3S-10 Series” manufactured by Sinloich. .

The average particle size of these fluorescent pigments is mainly 0.1.
Those having a thickness of 1 to 2 μm are used. When the average particle size of the fluorescent pigment exceeds 2 μm, there arises a problem that the coated surface is roughened during the production of the thermal transfer sheet, and the adhesion of the ink to the image receiving paper at the time of melting of the ink is inhibited, and the thermal transferability is reduced. This causes problems such as generation of voids and blurring of details during printing. If the average particle size is less than 0.1 μm, a sufficient fluorescence concentration cannot be obtained.

Examples of the resin for impregnating the fluorescent dye include the following. Ethylene-vinyl acetate resin (EVA), ethylene-acrylate copolymer (EEA), polyethylene, polypropylene, polybutene, polystyrene, styrene-acrylonitrile copolymer, petroleum resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer Polymer, polyvinyl alcohol, vinylidene chloride resin, methacrylic resin, polyamide, polyvinyl formal, polyvinyl butyral, polyvinyl acetate, polyisobutylene, polyurethane, alkyd resin, aromatic sulfonamide resin, urea resin, melamine resin, benzoguanamine resin, or Polyacetal or the like can be used.

In the present invention, the fluorescent pigment is preferably contained in the thermal transfer ink layer 2 in an amount of 20 to 70% by weight.
More preferably, the content is 30 to 60%. When the content of the fluorescent pigment is 20% or less, a sufficient print density cannot be obtained, and when the content is 70% or more, the transfer sensitivity is lowered and sufficient thermal transferability cannot be obtained.

Examples of the heat-fusible substance include waxes, and typical examples thereof include microcrystalline wax, carnauba wax, paraffin wax, and the like. Further, Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, Various waxes such as beeswax, spermaceti, Ibota wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax, fatty acid ester and fatty acid amide can be used.

These waxes can be added as they are, or they can be used as an aqueous emulsion. As the aqueous medium used for the aqueous emulsion,
Water or a mixture of water and a water-soluble organic solvent, for example, methanol, ethanol, isopropanol, etc., and a small amount of an emulsifier (surfactant) as required for these aqueous solvents.
Alternatively, a dispersion can be prepared by adding an additive such as a leveling agent. A dispersion having a solid content (wax) concentration of 10 to 50% by weight is used. Further, in the aqueous dispersion of the wax, it is possible to use a mixture of a drying oil, a resin, a mineral oil, a derivative of cellulose and rubber, and the like.

Examples of the binder resin include thermoplastic resins having a relatively low melting point, such as ethylene vinyl acetate resin (EVA), ethylene-acrylate copolymer (EEA), polyethylene, polypropylene, polybutene, and polystyrene. Styrene-acrylonitrile copolymer, petroleum resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, vinylidene chloride resin, methacrylic resin, polyamide, polycarbonate, fluororesin, polyvinyl formal, polyvinyl butyral, acetyl Cellulose, nitrocellulose, polyvinyl acetate, polyisobutylene, ethyl cellulose,
Polyurethane, polyacetal, or the like can be used. In particular, among resins conventionally used as heat-sensitive adhesives, those having a relatively low softening point, for example, 50 to 80 ° C. are preferable.

[0022]

The present invention will be described in detail below with reference to examples and comparative examples. Hereinafter, all parts or percentages are shown on a weight basis.

Example 1 Fluorescent Pink Pigment Emulsion (Shinloych Color Base SP-17, average particle size around 0.5 μm, 40% pure) 40 parts Ethyl acrylate emulsion (Toho Chemical Co., 25% pure) 5 parts Carnauba wax emulsion (manufactured by Konishi, 40% pure) 35 parts Paraffin wax emulsion (manufactured by Konishi, 40% pure) 20 parts Surfactant (Surflon S-132, manufactured by Asahi Glass Co.) 0.13 part 50% isopropanol Aqueous solution 30 parts After sufficiently dispersing the above components using an attritor, a 4.5 μm-thick polyethylene terephthalate film was used as a base film, and the above fluorescent ink composition was coated on one surface with a gravure coating method. To 4.0 g / m
² (dry state) and dried at 90 ° C. to obtain an ink layer having a smooth surface.

Example 2 The following fluorescent ink composition was prepared in the same manner as in Example 1, and a thermal transfer sheet was obtained in the same manner as in Example 1 using the same base film as in Example 1. Fluorescent yellow pigment emulsion (Shinloich Color Base SP-15, average particle size 0.5 μm, 40% pure) 40 parts Ethyl acrylate emulsion (Toho Chemical Co., 25% pure) 5 parts Carnauba wax emulsion (Konishi) 35 parts paraffin wax emulsion (manufactured by Konishi Co., Ltd., 40% pure) 20 parts Surfactant (Surflon S-132, manufactured by Asahi Glass Co., Ltd.) 0.13 parts 50% isopropanol aqueous solution 30 parts

Example 3 The following fluorescent ink composition was prepared in the same manner as in Example 1, and a thermal transfer sheet was obtained in the same manner as in Example 1 using the same base film as in Example 1. Fluorescent Yellow Pigment Emulsion (Shinloych Color Base SP-15, Average Particle Size 0.5 μm, Pure Content 40%) 40 parts Cyanine Green (FUJI SP GREEN 7188, manufactured by Fuji Dye Co., Ltd., Pure Content 30%) 2 parts Ethyl acrylate emulsion ( 5 parts Carnauba wax emulsion (manufactured by Konishi, 40% pure) 35 parts Paraffin wax emulsion (manufactured by Konishi, 40% pure) 20 parts Surfactant (Surflon S-132) , Manufactured by Asahi Glass Co.) 0.13 parts 50% isopropanol aqueous solution 30 parts

Example 4 The following fluorescent ink composition was prepared in the same manner as in Example 1, and a thermal transfer sheet was obtained in the same manner as in Example 1 using the same base film as in Example 1. Fluorescent pink pigment emulsion (Shinloich Color Base SW-17, average particle size 1 μm, 40% pure) 40 parts Ethyl acrylate emulsion (Toho Kagaku, 25% pure) 5 parts Carnauba wax emulsion (Konishi, Pure) 35 parts Paraffin wax emulsion (Konishi, 40% pure) 20 parts Surfactant (Surflon S-132, Asahi Glass) 0.13 parts 50% isopropanol aqueous solution 30 parts

Example 5 The following fluorescent ink composition was prepared in the same manner as in Example 1, and a thermal transfer sheet was obtained in the same manner as in Example 1 using the same base film as in Example 1. Fluorescent pink pigment emulsion (Shinloich Color Base 3S-17, average particle size 1 μm, 40% pure) 40 parts Ethyl acrylate emulsion (Toho Kagaku, 25% pure) 5 parts Carnauba wax emulsion (Konishi, Pure 35 parts Paraffin wax emulsion (Konishi, 40% pure) 20 parts Surfactant (Surflon S-132, Asahi Glass) 0.13 parts 50% isopropanol aqueous solution 30 parts

Example 6 The following fluorescent ink composition was prepared in the same manner as in Example 1, and a thermal transfer sheet was obtained in the same manner as in Example 1 using the same base film as in Example 1. Fluorescent pink pigment emulsion (Shinloich Color Base SW-17, average particle size 1 μm, 40% pure) 50 parts Ethyl acrylate emulsion (Toho Chemical Co., 25% pure) 5 parts Carnauba wax emulsion (Konishi, Pure 40 parts) 30 parts Paraffin wax emulsion (manufactured by Konishi, 40% pure) 15 parts Surfactant (Surflon S-132, manufactured by Asahi Glass Co.) 0.13 parts 50% isopropanol aqueous solution 30 parts

Example 7 The following fluorescent ink composition was prepared in the same manner as in Example 1, and a thermal transfer sheet was obtained in the same manner as in Example 1 using the same base film as in Example 1. Fluorescent pink pigment emulsion (Shinloich Color Base SW-17, average particle size 1 μm, 40% pure) 20 parts Ethyl acrylate emulsion (Toho Chemical Co., 25% pure) 5 parts Carnauba wax emulsion (Konishi, Pure 40 parts) 45 parts Paraffin wax emulsion (manufactured by Konishi Co., 40% pure) 30 parts Surfactant (Surflon S-132, manufactured by Asahi Glass Co.) 0.13 parts 50% isopropanol aqueous solution 30 parts

Example 8 The following fluorescent ink composition was prepared in the same manner as in Example 1, and a thermal transfer sheet was obtained in the same manner as in Example 1 using the same base film as in Example 1. Fluorescent pink pigment emulsion (Shinloich Color Base SW-17, average particle size 1 μm, pure content 40%) 70 parts Ethyl acrylate emulsion (Toho Chemical Co., Ltd., pure content 25%) 5 parts Carnauba wax emulsion (Konishi Corporation, pure 15 parts Paraffin wax emulsion (manufactured by Konishi, 40% pure) 10 parts Surfactant (Surflon S-132, manufactured by Asahi Glass Co.) 0.13 parts 50% isopropanol aqueous solution 30 parts

Example 9 The following fluorescent ink composition was prepared in the same manner as in Example 1, and a thermal transfer sheet was obtained in the same manner as in Example 1 using the same base film as in Example 1. Fluorescent pink pigment emulsion (Shinloich Color Base SW-17, average particle size 1 μm, 40% pure) 10 parts Ethyl acrylate emulsion (Toho Chemical Co., 25% pure) 5 parts Carnauba wax emulsion (Konishi, Pure 50 parts Paraffin wax emulsion (manufactured by Konishi, 40% pure) 35 parts Surfactant (Surflon S-132, manufactured by Asahi Glass Co.) 0.13 parts 50% aqueous solution of isopropanol 30 parts

Example 10 The following fluorescent ink composition was prepared in the same manner as in Example 1, and a thermal transfer sheet was obtained in the same manner as in Example 1 using the same base film as in Example 1. Fluorescent pink pigment emulsion (Shinloich Color Base SW-17, average particle size 1 μm, 40% pure) 80 parts Ethyl acrylate emulsion (Toho Chemical Co., 25% pure) 5 parts Carnauba wax emulsion (Konishi, Pure 40 parts) 10 parts Paraffin wax emulsion (manufactured by Konishi, 40% pure) 5 parts Surfactant (Surflon S-132, manufactured by Asahi Glass Co.) 0.13 parts 50% isopropanol aqueous solution 30 parts

Comparative Example 1 The following fluorescent ink composition was prepared in the same manner as in Example 1, and a thermal transfer sheet was obtained in the same manner as in Example 1 using the same base film as in Example 1. Fluorescent pink pigment (Sinloich Color FA-47, average particle size 3.5-4.5 μm) 16 parts Ethyl acrylate emulsion (Toho Chemical Co., Ltd., 25% pure) 5 parts Carnauba wax emulsion (Konishi Co., Ltd.) 35 parts Paraffin wax emulsion (manufactured by Konishi, 40% pure) 20 parts Surfactant (Surflon S-132, manufactured by Asahi Glass Co.) 0.13 parts 50% isopropanol aqueous solution 30 parts

The thermal transfer ink ribbon obtained as described above was applied to a commercially available label printer (resolution: 300 dp).
i, printing speed of 100 mm / sec), printing on art paper, printing of solid (evaluation of transferability), 50% halftone (evaluation of sharpness), 1dot vertical fine line (evaluation of fine blur), and About print density,
Judgment was made according to the following evaluation criteria, and the results shown in Table 1 were obtained.

Evaluation Criteria 1) Transferability ：: No generation of voids ：: Negligible generation of voids ：: Occurrence of voids is somewhat noticeable ×: Occurrence of voids is noticeable 2) Sharpness ：: Occurrence of blurring No: Occurrence of rubbing is negligible. 目: Occurrence of rubbing is somewhat conspicuous. X: Occurrence of rubbing is conspicuous. 3) Detail blurring ◎: No fine line missing. Omission is somewhat conspicuous. X: Omission of fine lines is conspicuous.

[0036]

[Table 1]

[0037]

As described above, in the thermal transfer recording medium of the present invention, the thermal transfer recording medium having a thermal transfer ink layer composed of a fluorescent pigment and a binder resin formed on one surface of a base material has an average content of the fluorescent pigment. Since the particle size is 0.1 to 2 μm, a thermal transfer recording medium excellent in transferability, sharpness, fine blur, and print density can be obtained.

In the thermal transfer recording medium of the present invention, even when an ink layer is formed by using a large amount of a fluorescent pigment, the thermal dye does not bleed out, so that the thermal head is not stained and is clear. Characters and images having a fluorescent color with excellent surface smoothness can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a thermal transfer recording medium of the present invention.

FIG. 2 is a longitudinal sectional view showing another example of the thermal transfer recording medium of the present invention.

FIG. 3 is a longitudinal sectional view showing still another example of the thermal transfer recording medium of the present invention.

[Explanation of symbols]

 1 base material 2 thermal transfer ink layer

Claims (2)

[Claims] 1. A thermal transfer recording medium comprising a thermal transfer ink layer having at least a thermal transferable fluorescent ink layer containing a fluorescent pigment on one surface of a substrate, wherein the average particle size of the fluorescent pigment in the fluorescent ink layer is A thermal transfer recording medium having a thickness of 0.1 to 2 μm. 2. The method according to claim 1, wherein the content of the fluorescent pigment in the fluorescent ink layer is 2
2. The thermal transfer recording medium according to claim 1, wherein the content is 0 to 70% by weight.