JPS61211089A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To enhance color density of transferred images and enable a fluorescent color with high intensity to be obtained, by a construction wherein a fluorescent substance having a melting or softening point of 50-140 deg.C is used in an ink layer in proximity to a heat-resistant base. CONSTITUTION:The heat-fusible ink layer 11 comprises a fluorescent substance 2 in proximity to the heat-resistant base 10 and a coloring agent in proximity to the outer surface of the layer 11, and is bound by a wax or resin binder 4. The ink layer 11 is melted and transferred onto a transfer paper 6 by a printing means such as a thermal head 5, whereby an image 12 with high fluorescent intensity and high color density can be formed. The wax form substance or resin may any one which shows a melting or softening point of 50-140 deg.C in the state of a solid solution with a fluorescent dye and can be dyed with a fluorescent dye. Since such a solid solution undergoes depletion of density and a reduction in fluorescent intensity when the concentration of the dye is not less than a certain value, the concentration of the dye is suitably about 0.1-5.0wt%.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a thermal transfer recording medium for recording fluorescent prints on recording paper by utilizing the heat-melting properties of an ink layer containing fluorescent light.

Prior Art Conventionally, thermal transfer recording media have been provided with a heat-melting ink layer containing a coloring agent made of dye and/or pigment, a wax as a fixing agent, and a resin binder on a heat-resistant support such as a polyester film. things are known. The print recording method using such a recording medium is carried out by overlapping recording paper on the surface of the heat-melting ink layer of the medium, applying a thermal head from the recording medium side, and melting and transferring the ink layer in that area onto the recording paper. It will be done.

However, if the records thus obtained are used for special purposes, such as checks, postage stamps, etc., there is a risk that they will be forged. Therefore, for example, it is possible to include a fluorescent substance in the ink layer.

That is, in this case, the transferred image is a normal colored image under normal conditions (no light of a specific excitation wavelength), but it emits fluorescent light when irradiated with light of a specific excitation wavelength, making it possible to prevent counterfeiting. In this case, fluorescent substances such as general fluorescent dyes and fluorescent pigments have low coloring power and therefore need to be used in large amounts. However, since the fluorescent substance is not sensitive to heat, when used in such a large amount, the thermal transfer characteristics of the ink layer deteriorates, causing blurring, unevenness, etc. of the transferred image.

Object The object of the present invention is to provide a thermal transfer recording medium that is free from the risk of forgery, has excellent transfer printing quality, has high color density in a transferred image, and can provide a high-intensity fluorescent color.

Structure The thermal transfer recording medium of the present invention has dye and/or dye on a heat-resistant support.
Alternatively, in a thermal transfer recording medium provided with a heat-melting ink layer containing a colorant consisting of a pigment, a fluorescent substance, a wax fixing agent, and a resin binder as main components, the fluorescent substance in the ink layer is
It has a melting point or softening point of 0 to 140°C, and is made of a waxy substance solid solution and/or resin solid solution of a fluorescent dye in which the waxy substance or resin part is dyed with a fluorescent dye, and this fluorescent substance is present in the vicinity of the heat-resistant support.

The present inventor has incorporated a fluorescent substance into the heat-melting ink layer for the purpose of preventing counterfeiting, and has achieved satisfactory color density and fluorescent intensity of the printed image without deteriorating the quality of thermal transfer printing even when used in large amounts. As a result of intensive research into thermal transfer recording media having a heat-melting ink layer, the present invention has been completed.

Fluorescent dyes or fluorescent pigments are generally used as fluorescent substances. If such a fluorescent substance is added to a conventional heat-melting ink layer, the prevention of forgery of recorded materials, which is the object of the present invention, can be achieved to some extent. In other words, the transferred image obtained from such a hot-melt ink layer containing a fluorescent substance (including a coloring agent) has the same appearance as a normal colored image, but the transfer image obtained from such a heat-melting ink layer containing a fluorescent substance (including a coloring agent) has the same appearance as a normal colored image. They can be distinguished from ordinary colored images because they emit fluorescent light when exposed to (excited light).

However, fluorescent dyes and fluorescent pigments are not heat sensitive, so if the ink layer contains a large amount of fluorescent substance in order to obtain sufficient fluorescence intensity, the thermal transferability of the ink layer will decrease and the transferred image will not be visible. This may cause scratches, unevenness, etc. On the other hand, in the present invention, the thermal transferability can be improved by using a fluorescent material in which the fluorescent dye has wax-like or resin-like properties, and thus has heat sensitivity.

On the other hand, when a fluorescent substance and a coloring agent are mixed and used, and if the coloring agent has an absorption band that absorbs fluorescence, the fluorescence intensity of this mixture (in a solid state) will depend on the direction inside the volume. The involvement of fluorescent substances is extremely small. This is believed to be due to the filtering effect of the colorant and the reabsorption of fluorescent light. Therefore, it can be said that the intensity of the fluorescent light is determined by how many fluorescent substances are present near the surface of the printed image. Therefore, in the thermal transfer recording medium of the present invention, by making more fluorescent substances exist near the support, more fluorescent materials can be made to exist on the surface of the thermal transfer printed image or in the vicinity thereof. It is possible to emit high-intensity fluorescent light.

To explain the present thermal transfer recording medium with reference to the drawings, in FIG. 1, this recording medium 1 has a heat-melting ink layer lif! : provided, the ink layer 1
1 has a fluorescent substance 2 in the vicinity of a heat-resistant support 10 and a colorant 3 in the vicinity of the layer surface. The fluorescent substance 2 and the coloring agent 3 are fixed by a wax and a resin binder 4 as a fixing agent. FIG. 3 shows another example of the thermal transfer recording medium of the present invention, and this recording medium 1 includes a first heat-melting ink layer 13 containing a fluorescent substance 2 and a colorant 3 on a heat-resistant support 10. The second thermofusible ink layer 14
are provided in sequence. 4 is a wax and a resin binder.

Therefore, for example, if printing is performed on a transfer paper using a thermal transfer recording medium as shown in FIG.
1 is melt-transferred onto a transfer paper 6, and an image 12 with high fluorescent intensity and color density is formed, with a fluorescent substance 2 on the surface of the printed image and a coloring agent 3 underneath.

Next, each component used in the present invention will be explained.

First, as the fluorescent substance, a wax-like solid solution and/or resin is used, which is a fluorescent dye that has wax-like or resin-like properties, and thus has heat sensitivity, so that thermal transferability does not deteriorate even when used in large amounts as described above. A solid solution is used. The waxy substance or resin used in these solid solutions has a melting point or softening point of 50 to 140°C when made into a solid solution with a fluorescent dye.
Any material that falls within this range and can be dyed with fluorescent dyes can be used. In order to satisfy the latter condition, a material having a polar group (for example, an amide group, an ester group, a hydroxyl group, a lactone bond, an acrylic group, etc.) that is compatible with the fluorescent dye is selected. Specifically, it is as follows.

For reference, the melting point or softening point is also shown. First, the waxy substance is stearic acid monoethanolamide (
mp91-95°C), lauric acid monoethanolamide (mp80-84°C coconut oil fatty acid monoethanolamide (mp67-71'C), rubitan behenic acid ester (mp68.5°C), rubitan stearate (mp67-71'C), mp51”c), glycerin monostearate (mp63-68℃), acetyl sorbitol (
mp99.5℃), benzoyl tsurupit) (mp127
°C), acetylmannite (mp l 19-120
℃) etc., and as a resin, polycaprolactone with a number average molecular weight of 10,000 (mp 60-65℃), average molecular weight 6
000 polyethylene glycol (MP62℃), low condensation polymerization melamine/toluenesulfonamide resin (softening point 1
05°C), low condensation polymerized benzyltoluenesulfonamide resin (softening point 68°C), acrylic resin (softening point 85°C),
Examples include linear polyamide resin (softening point: 60°C). On the other hand, fluorescent dyes for dyeing the above waxy substances or resins include thioflavin (CI 49005); basic yellow HG (CI 46040); fluorescein (CI 45350); rhodamine B (CI 45).
170); Rhodamine 6G (CI45160); Eosin (CI15380); Common white fluorescent brighteners, such as CI Fluorescent Brightening Agent 85, CI 166, CI 174; Others, and the above fluorescent dyes. Oil-solubilized (and water-insolubilized at the same time) with organic acids, such as Oil Pin Funa 312, which is made oil-solubilized with Rhodamine B, and Varifast Red 1308, which is made oil-solubilized with Rhodamine 6G.
(The above are manufactured by Orient Kagaku Co., Ltd.); and the above fluorescent dyes made into lakes with metal salts and other precipitants, such as First Rose and First Rose Conc made into lakes of Rhodamine 6G (The above are made by Dainichiseika Chemical Co., Ltd.) ) etc.

Methods for producing the solid solution of the present invention using the above-mentioned materials include a lump resin pulverization method, an emulsion polymerization method, a resin precipitation method, etc. Among them, a lump resin pulverization method is preferred. Here, the lump resin pulverization method (British Patent No. 845462) is a method in which resin and fluorescent dye are melted and mixed, cooled and solidified, and the resulting lump is pulverized, and the emulsion polymerization method (British Patent No. 8
No. 22709) is a method in which a resin powder obtained by emulsion polymerization is added to a hot aqueous solution of a fluorescent dye to exhaust the dye into the resin powder, which is then filtered and dried. and A in an aqueous solution containing a fluorescent dye.
/.

(804) Add an aqueous solution of a water-soluble metal salt such as This is then filtered and dried.In addition, the fluorescence intensity of the solid solution obtained as described above increases as the concentration of the fluorescent dye increases, but when the concentration exceeds a certain level, the concentration is exhausted and the fluorescence becomes weak. The light intensity decreases.For this reason, the proportion of the fluorescent dye in the solid solution is suitably about 0.1 to 5.0% by weight.

Next, an example of producing a wax-like substance or resin solid solution of a fluorescent dye by the above-mentioned bulk resin crushing method will be shown.

All parts are by weight.

Production example 1 fil low polycondensation benzyltoluenesulfonamide resin
97.5 part price) Rhodamine B Extra
1.0 part (, J Rhodamine 6GDN Extra
1.0 parts (dl brilliant sulfofurapine
Prepare 0.5 part of (IL) and melt it by heating to 100℃, and when it becomes transparent, increase the temperature to 170-180℃.
cause it to rise. Then add (bl, (c) and (
d) was added and dissolved, cooled and solidified, and then pulverized to obtain a resin solid solution with a softening point of 105° C. that emits reddish-orange fluorescence. The maximum wavelength of fluorescence of this substance is 605 nm, and also? The relative fluorescence intensity when formed into a 10 μm thick film on a diester film was 112. These performances were measured using a Hitachi 65G-60 fluorescence spectrophotometer with a scan speed of 12 Qnm/min and a slit width of 1 nW on both the excitation and emission sides! Measured under the following conditions.

Production Examples 2 to 6 Waxy substance solid solutions or resin solid solutions of fluorescent dyes were prepared in the same manner as in Production Example 1 using waxy substances or resins and fluorescent dyes having the following formulations.

Prescription for Production Example 2: Chain polyamide resin 97.5 parts Rhodamine B Extra 1.0 parts Rhodamine 6GDN Extra 1.0 parts Brilliant Sulfoflavin 0.5 parts Prescription for Production Example 3: Sorbitan (henedioic acid ester 98.5 parts) 590-Damin B Extra 0.6 parts Rhodamine 6GD
N Extra 0.6 parts Brilliant Sulfoflavine 0.3 parts Formula for Production Example 4: Coconut oil fatty acid monoethanolamide 99.5 parts Brilliant Sulfoflavine 0.5 parts Formula for Production Example 5: Sorgitan behenic acid ester 96 .5 parts Formula of Production Example 6: Chain-like lyamide resin 73.1 parts Sorbitan behenate ester 24.4i Rhodamine B Extra 1.0 parts Rhodamine 6GDN Extra 1.0 parts Brilliant Sulfofragine
The maximum fluorescence wavelength, fluorescence color and relative fluorescence intensity of each solid solution obtained in the above manner at 0.5 parts or more are shown in Table 1. Also include the melting point or softening point.

Table 1 The solid solution fluorescent substance of the present invention is commercially available, such as FZ-2000 (softening point 110°C) manufactured by Shinroihi Co., Ltd., FZ-2000 (softening point 110°C),
3000 (softening point 120-130℃), BO-100 (
Softening point: 90-100℃), FM-LL (Softening point: 11
0 to 125°C) (hamelamine/toluenesulfonamide resin system); 5M-13 (softening point 71°C), 5R-1
0 (softening point 90°C) (the above are acrylic resin-based), etc. are available.

The amount of the solid solution fluorescent substance to be used can be arbitrarily selected depending on the fluorescence intensity of the transfer layer, but is generally about 20 to 70%, preferably about 30 to 60%, of the weight of the ink layer.

Next, other materials used for the heat-melting ink layer will be explained.

First, dyes or pigments used as colorants may be those commonly used in this field. That is, the dyes include oil-soluble dyes, such as Sumikalo Yino Iolet R8, Dianix 7 Earth Tono Iolet 3R-FS, Kayalon Boliol Brilliant Blue N-BGM (the above are anthraquinone dyes), Kayalon Polyol Brilliant Blue BM, Kayalon Polyol Brilliant Blue BM, Kayalon Polyol Brilliant Blue N-BGM Ronpolyol Dark Blue 2BM,
Sumikaron Diazo Black 5G.

Mikutacel Black 5GH (azo dye), Direct Dark Green B, Direct Brown M1 Direct 7 Asto Black D (direct dye), Kayanol Milling Cyanine 5R (acidic dye), Sumikalishi Blue 6G, Fuizen malachite green, rhodamine B
Examples include 10-damine 6G, Victoria Blue (the above are basic dyes), and the like. On the other hand, pigments include Victoria Blue Lake, metal-free phthalocyanine, phthalocyanine,
7 Ast Sky Blue, Nozomanent Red 4R, Brilliant Fast Scarlet, Brilliant Carmen BS, Nosomanent Carmine FB, Lysole Red, Permanent Red F'SR, Delirious Carmine 6B, Pigment Scarlet 3B, Rhodamine Lake B, Rhoda Minley? T, Alisarin Lake, Fast Red, Silite Ret G Toner, Lionol Red CP-A, Chrome Yellow (yellow lead), Zinc Yellow Zinc Chromate (MU), Lemon Yellow (chromic acid); Cadmium Yellow, Naphthol Yellow B, Hansa Yellow-5G1 Hansa Yellow 3G1 Hansa Yellow ○, Hansa Yellow A1 Hansa Yellow RN, Hansa Yellow R, Benzidine Yellow,
Examples include benzidine yellow G, benzidine yellow GR, permanent yellow NCG, quinoline yellow lake, and fast yellow. In the present invention, pigments are preferable in terms of light resistance, color migration properties, dissolution resistance, and the like.

Next, waxes will be explained. Waxes are used as fixing agents to fix dyes and/or pigments, fluorescent substances, etc. onto a support. Such waxes include carnauba wax, oculie wax, microcrystalline wax, norahin wax, ceresin wax, -fV'77Ff/l'/montan wax, candelilla wax, shellac wax, chuuhaku wax, and nogu-
Examples include easily heat-meltable waxes or resins such as wax, beeswax, low molecular weight polyethylene, and polyvinyl stearate.

Next, as a binder, polyvinyl chloride, polyvinyl acetate,
Polyvinyl fluoride, polyvinyl butyral, polyvinylidene chloride, polyvinyl alcohol, vinyl chloride-♂yl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, polystyrene, teriethylene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer Examples include resins that can be easily heat softened or melted, such as polymers, acrylonitrile-styrene-butadiene copolymers, cellulose esters, cellulose ethers, and petroleum resins.

In addition, a softener can be added to the heat-melting ink layer. Examples of the softener include liquid norafin, mineral oil, animal oil (eg, whale oil), vegetable oil (eg, rapeseed oil), and the like. The amount used is suitably 2% or less of the weight of the ink layer.

As a heat-resistant support, polyester film, / +7
Propylene film, polyimide film, polycarbonate film, plastic paper, condenser paper, etc. are used. Appropriate thickness is about 3 to 20 microns.

The method for producing the thermal transfer recording medium of the present invention is as follows: (1) separately preparing a heat-melting ink containing a fluorescent substance and a heat-melting ink containing a colorant (not containing a fluorescent substance); A method of forming a two-layer heat-melting ink layer by coating an ink containing a fluorescent substance and an ink containing a colorant on a heat-resistant support; (2) determining the difference in specific gravity between the fluorescent substance and the colorant; A heat-melting ink containing a fluorescent substance and a colorant is coated on a heat-resistant support so that the fluorescent substance is present closer to the support and the colorant is present closer to the surface of the ink layer. Although there are methods for forming a heat-fusible ink layer in the mold, method (1) is advantageous.

To explain method (1) in more detail, a heat-melting ink containing a fluorescent substance, waxes, and a binder (hereinafter referred to as fluorescent ink) is melt-coated onto a heat-resistant support to give a 1-4μ After forming a first heat-melt ink layer with a thickness of approximately 1 to 4 μm, a heat-melt ink containing a colorant, waxes, and a binder (hereinafter referred to as colored ink) is applied thereon by t-melting to a thickness of 1 to 4 μm. By forming the second heat-fusible ink layer of about 100 to 100%, a thermal transfer recording medium having a laminated heat-fusible ink layer can be obtained. However, the thickness of the entire heat-melting ink layer is 3
~6μ is preferable. Additives such as softeners can be added to these ink layers as other components.

This type of additive can also be used in method (2). In any case (in method 11, the ink is applied (and dried if necessary) quickly so that the two ink layers do not mix as much as possible due to thermal diffusion during coating film formation.Furthermore, depending on the print recording conditions, The optical ink may not be completely transferred, resulting in uneven fluorescence on the printed matter.

In this case, the waxes used for each ink include carnauba wax, which has excellent transferability, hydrogenated castor oil,
Good results can be obtained by using candelilla wax or the like, or by delaying the peeling of the head after printing a little later than usual.

In both cases where the heat-melt ink layer is formed as two layers as described above, or when the heat-melt ink layer is formed as a single layer as in method (1) above, fluorescent substances and colorants are used. , waxes, and binders are used in amounts of 5 to 40% by weight and 1 to 3% by weight, respectively, based on the entire heat-melting ink layer.
Suitable amounts are 0% by weight, 40-90% by weight, 2-20% by weight, particularly 10-25% by weight, 3-15% by weight.
, 75 to 85% by weight, and preferably 3 to 15% by weight. The amount of additive used is usually 2% by weight or less based on the entire heat-melt ink layer.

In order to print and record using the thermal transfer recording medium of the present invention, as in the past, a recording sheet is placed on the ink layer surface of the recording medium, and a thermal head is applied from the recording medium side to transfer the ink layer of that portion onto the recording sheet. Just transcribe it.

The present invention will be explained below by way of examples. Note that all parts are parts by weight.

Examples 1 to 2 A fluorescent ink and a blue ink having the following compositions were respectively melted and dispersed to form a uniform dispersion.

Fluorescent ink (red-orange fluorescent): Fluorescent material made in Production Example 6 50.0 parts Candelilla wax 49.0 parts Fluid rough-in
1.0 parts Colored ink (red): Carnauba wax A1 39.5 parts Paraffin (155”F) 39.5 parts Petroleum resin
5 parts Fluid/Cerafin 1 part Fluorescent ink was then melt-coated onto a 6μ thick polyester film so that the film thickness would be as shown in Table 1 below to form a first thermofusible ink layer (hereinafter referred to as fluorescent). After forming a second heat-melting ink layer (hereinafter referred to as a colored ink layer), a colored ink is melt-coated on top of the optical ink layer so that the film thickness becomes the value shown in the table. A thermal transfer recording medium was made by forming a .

*1: Ratio of fluorescent substance to the entire fluorescent and colored ink layer Class 2: Ratio of colorant to the entire fluorescent and colored ink layer Comparative Example 1 Rhodamine B Extra-Rhodamine 6 as the fluorescent substance
Fireflies were produced in the same manner as in Example 1, except that a triazine resin solid solution of GDN mixed (t:i) dye (red orange color FA-41 manufactured by Shinroihi Co., Ltd., softening point 150°C or higher) (by the lump resin crushing method) was used. A light ink and a colored ink were prepared. Next, add both inks to fluorescent ink/colored ink = 1
/ t (by weight), a mixed ink containing a fluorescent substance and a colorant at the same concentration as in Example 1 (fluorescent substance 25.5% by weight).
0%, colorant 7.5%) ft, and this was made into a 6μ thick d
? A thermal transfer recording medium having a single heat-melting ink layer was prepared by melt-coating the Soliester film so that the top coat thickness was 4.0 μm.

Comparative Example 2 A heat-fusible ink layer was prepared in the same manner as in Comparative Example 1, except that the following composition was used as a mixed ink (50% fluorescent material and 7.5% colorant for the entire fluorescent and colored ink layer). created a single-layer type thermal transfer recording medium.

Mixed ink: Red Orange Color FA-4150, 0 parts Norred CP-A 5.0 parts Seika First Yellow 2200M 2.5 parts Carnauba wax
7.5 camp relax
14.0 parts paraffin (rnp, approx. 68.5°C)
15.0 parts petroleum resin 5.0 parts fluid flow rough-in 1.0 parts or more A commercially available transfer paper for PPC (plain paper copying machine) is placed on the ink layer surface of the recording medium, and heating energy is applied to the thermal head o,
somJ / dot (8 dots / ta head) and pressing is applied from the recording medium side under the condition of a pressure of about 50017ai, and after melting and transferring each ink layer of that part onto the transfer paper, the recording medium is pressed after lOOm sea. Print recording was performed by peeling off the paper at an acute angle to the surface of the transfer paper. The results are shown in Table-2.

In addition, the fluorescence spectral values of the above-mentioned recording media and printed matter were measured and are shown in Table 2.

(The following is a blank space) As is clear from this table, the products of the present invention emit fluorescent light with higher intensity than the comparative products, even though the same concentration of fluorescent substance was used. In order to obtain the same intensity of fluorescent light as in Example 1 in the comparative product, as in Comparative Example 2, approximately 25% of the fluorescent substance is enclosed in the ink layer, and as a result, fading occurs particularly in the fine line portions of the print.

Effects As described above, since the thermal transfer recording medium of the present invention contains a fluorescent substance in the heat-melting ink layer, it is not only possible to prevent forgery of printed images, but also to prevent wax-like or resin-like properties from being imparted to the fluorescent substance. By containing this in the vicinity of the support, the color density and fluorescent color intensity of the printed transfer image can be increased, and the thermal transferability and therefore the print quality can be improved.

[Brief explanation of the drawing]

1 and 3 are cross-sectional views of the thermal transfer recording medium of the present invention,
FIG. 2 is an explanatory diagram of the print recording method using this recording medium, and FIG. 4 is a companion diagram for measuring the fluorescence spectra of the thermal transfer recording media prepared in Examples and Comparative Examples. 1... Thermal transfer recording medium of the present invention 2... Fluorescent substance 3... Colorant 4... Wax and binder 5... Thermal head 6... E photo paper 10,
l O'...Heat-resistant support (or 10 is the support side, 1
0' is the transfer paper side) 11... Heat-melting ink layer 12
...Printed transfer image 13...First thermofusible ink layer or fluorescent ink layer 14...Second thermofusible ink layer or eyebrow color ink layer Procedural amendment May 8, 1985 Thermal transfer recording Media 3, Relationship with the person making the amendment Patent applicant Rico Co., Ltd. 1-3-6 Nakamagome, Ota-ku, Tokyo (674) - Representative Hama 1) Hiro 4, agent Akira, taV's "invention" Column 6 of ``Detailed explanation of
．． Corrected to 8J.

Claims (1)

[Claims] 1. In a thermal transfer recording medium in which a heat-melting ink layer containing a colorant consisting of a dye and/or pigment, a fluorescent substance, a wax fixing agent, and a resin binder as main components is provided on a heat-resistant support, the ink layer A solid solution of a fluorescent dye in a waxy substance and/or a resin in which the fluorescent substance therein has a melting point or softening point of 50 to 140°C, and the waxy substance or resin portion is dyed with a fluorescent dye. 1. A thermal transfer recording medium comprising a solid solution and having this fluorescent substance present in the vicinity of a heat-resistant support.