JPH0464489A - Thermal transfer recording sheet - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer recording sheet which can prevent alteration from occurring by applying a heat-resistant layer to the single surface of a base material and providing a hot melt ink layer based on carbon black, wax and a resin to the opposite surface thereof. CONSTITUTION:A thermal transfer recording sheet is obtained by applying a heat-resistant layer to the single surface of a base material and providing a layer containing hot melt ink based on carbon black, wax and a resin and white inorg. fluorescent pigment having an emission max. wavelength of 400-700nm and a particle size of 0.5-5.0mum to the opposite surface thereof. The inorg. fluorescent pigment can not be visually confirmed though it has a white hue because the particle size is as small as 0.5-5.0mum. In the combination of the thermal transfer recording sheet and thermal transfer image receiving paper, the magnetic powder of the magnetic recording layer applied to the thermal transfer image receiving paper is composed of Ba-ferrite or Sr-ferrite.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal transfer recording sheet, and more specifically,
The present invention relates to a thermal transfer recording sheet capable of obtaining recorded images that are tamper-proof.

[Prior Art] In recent years, thermal printers and thermal facsimiles have been using thermal transfer recording sheets with heat-melting ink coated on a substrate to obtain clear and robust images on image-receiving paper. . This is a method in which the surface of the heat-melting ink layer of a thermal transfer recording sheet and an image-receiving paper are overlapped, and the ink is selectively heated from the non-ink layer surface of the base material using a thermal head according to an electric signal, and then transferred onto the image-receiving paper. The recording is completed when the thermal transfer recording sheet and the image receiving paper are peeled off.

Here, since a recorded image with robustness can be obtained, its application fields are wide-ranging. Among them, it is used in a wide range of fields related to money because of its robustness.

Examples include payment slips from financial institutions, airline tickets, train tickets, checks, securities, and the like. In addition, as those using thermal transfer image-receiving paper whose transfer surface is coated with a magnetic recording layer, magnetic train tickets, magnetic commuter passes, magnetic coupon tickets, magnetic parking tickets,
Examples include voting tickets for horse racing, bicycle racing, auto racing, etc., and prepaid cards (prepaid cards).

In the above-mentioned applications, there is a risk that the issuer of the ticket may be tampered with because it involves money, so various measures have been taken to prevent this.

There have been various references regarding thermal transfer recording sheets using fluorescent substances for the purpose of preventing tampering. For example, JP-A-59-54598, JP-A-61-2289.
Publication No. 94, etc. may be mentioned.

JP-A-59-54598 relates to a heat-sensitive fluorescent transfer medium in which a fluorescent pigment and a hot melt adhesive are contained in a heat-sensitive transfer ink layer provided on a base material. Here, a fluorescent pigment is used as a coloring agent, and the purpose is to visually confirm the hue of the fluorescent pigment and to identify strong fluorescence. However, there is a drawback that it is difficult to visually confirm the hue of the fluorescent pigment itself. Furthermore, in order to be visually confirmed, a large amount of fluorescent pigment must be contained, which increases costs.

JP-A-61-228994 discloses a thermal transfer recording medium in which a heat-melting ink layer containing a colorant, a wax, a binder, and a softener as main components is provided on a heat-resistant support. The present invention relates to a thermal transfer recording medium characterized by containing a fluorescent substance and using a coloring agent that absorbs little or no fluorescence from the fluorescent substance. The purpose of this invention is to solve the drawback that the fluorescence of the fluorescent substance is absorbed by the coloring agent and the fluorescence intensity decreases. As for the colorant, it is exemplified that a combination of a fluorescent material and a member of the same color is good. Specifically, red coloring agents are exemplified as red fluorescent substances, and similarly blue and yellow colorants are exemplified. That is, in this publication, there is a characteristic in the combination of the same colors, and there is no combination of different colors. Also, there is no description that corresponds to black recorded images.

[Problems to be Solved by the Invention] In a thermal transfer recording sheet formed by coating a heat-resistant layer on one side of a base material and coating a heat-fusible ink layer on the opposite side, a fluorescent substance is contained in the heat-fusible ink. As mentioned in the above cited example, the examples containing the above had various problems. - In boat fishing, black recorded images are often used, and although countermeasures have been taken to prevent tampering in the above-mentioned applications, there has been no effective method.

[Means for Solving the Problems] As a result of extensive research, the present inventors have provided a thermal transfer recording sheet that is tamper-proof.

That is, the thermal transfer recording sheet provided by the present invention is
A thermal transfer recording sheet in which a heat-resistant layer is coated on one side of a base material and a heat-melt ink layer is coated on the opposite side, and the heat-melt ink is mainly composed of carbon black, waxes, and resins. It further contains a white or pale white inorganic fluorescent pigment having a maximum emission wavelength of 400 to 700 nm and a particle size of 0.5 to 5.0 μm.

Further, the thermal transfer recording sheet provided by the present invention is
A heat-resistant layer is coated on one side of the base material, and a heat-melting layer 4 is coated on the other side.
In the thermal transfer recording sheet formed by coating 26 layers, the heat-melting ink is mainly composed of carphone black, waxes, and resins, and the ink has a thickness of 400 to 700 nm.
emission maximum wavelength, and 0. A thermal transfer recording sheet characterized by containing a white or pale white inorganic fluorescent pigment having a particle size of 5 to 5.0 μm, and a substrate having ferromagnetic magnetic powder on the surface opposite to the transfer surface. It consists of a combination with a thermal transfer image receiving paper coated with a magnetic recording layer as the main component.

The inorganic fluorescent pigment of the present invention includes (aS:Bi, SrS:
Sm:Ce, ZnS:Ag5ZnS:Cu.

ZnS: Sulfide system consisting of Cu: Co, 5r5 (PO,
)3 C1:Eu, 3 (Ba, Mg) ・8Al2
O3: Eu, ZnO: Zn, Zn, si.

: Mn, Zn 2 GeO 4 : M
n, YVO42 Eu, Y2O2 S: Eu,
It is characterized by using at least one kind of oxyacid salts consisting of 0.5MgF2, 3.5MgO, GeO2:Mn.

The inorganic fluorescent pigment of the present invention is contained in the heat-melting ink at 0.0%.
It is characterized by containing 5 to 40 weight percent.

In the combination of the thermal transfer recording sheet and thermal transfer image receiving paper of the present invention, the magnetic powder of the magnetic recording layer coated on the thermal transfer image receiving paper is Ba-ferrite or Sr ferrite.

The present invention will be specifically explained below.

The thermal transfer recording sheet of the present invention can be used for recording purposes that are likely to be tampered with, such as payment slips from financial institutions, airline tickets, train tickets, checks, securities, etc., and a magnetic recording layer coated on the transfer surface. This product uses thermal transfer image-receiving paper, and can be used for magnetic train tickets, magnetic commuter passes, magnetic coupon tickets, magnetic parking tickets, horse racing, bicycle races, etc.
It is intended to be used for purposes such as voting tickets for auto races, prepaid cards (advance payment cards), etc. Currently, there is a constant fear that these money-related items may be tampered with, so various preventive measures are currently being taken. In general, images recorded by thermal transfer recording are often black. In order to prevent tampering, it is meaningless if measures to prevent tampering can be visually confirmed.

The thermal transfer recording sheet of the present invention was completed by focusing on the fact that the inorganic fluorescent pigment of the present invention cannot be visually confirmed in a black heat-melting ink containing carbon black as a colorant. The reason why inorganic fluorescent pigments cannot be visually confirmed even though they have a white or pale white hue is because of their particle size.
This is because it is as small as 5 to 5.0 μm, preferably 1.0 to 3.0 μm. This is because the particle size within this range allows the inorganic fluorescent pigment to be sufficiently embedded since the heat-melting ink layer coated on the thermal transfer recording sheet usually has a layer thickness of 2 to 8 .mu.m. Particle size of inorganic fluorescent pigment is 0.5μ
If it is smaller than m, it is necessary to increase the content in the heat-melting ink, which affects the properties of the ink. vice versa,
If the particle size exceeds 5.0 μm, the particles will protrude from the heat-melting ink layer, which will have an adverse effect on recording.

The inorganic fluorescent pigment of the present invention can be used under black light (wavelength 36
When irradiated with light of a specific excitation wavelength such as 5 nm), it emits light in blue, green, or red.
Its maximum emission wavelength is 400 to 700 nm.

The inorganic fluorescent pigment in the heat-melting ink is characterized by being contained in an amount of 0.5 to 40% by weight in a composition containing carbon black, waxes, and resins as main components. 0. If it is less than 5% by weight, it is difficult to distinguish when irradiated with light of a specific excitation wavelength such as a black light.

On the other hand, when the amount exceeds 40% by weight, the hue of the hot-melt ink layer becomes grayish. In addition, thermofusible ink is not flexible and is brittle. It also becomes a factor in increasing costs.

Further, as a characteristic feature, the inorganic fluorescent pigment of the present invention has excellent heat resistance and weather resistance, so that a heat-melting ink can be stably produced.

There is no effect on the heat generated by the thermal head during thermal transfer recording. Since it is resistant to weather resistance such as light resistance and water resistance, the recorded image is highly tamper-proof.

The inorganic fluorescent pigment of the present invention will be specifically exemplified.

For example, CaS:Bi, SrS:Sm:Ce, ZnS
: AgX ZnS : CuS ZnS : Cu:
Sulfide system consisting of Co, etc., Sr5 (PO4)3Cl:
Eu, 3 (Ba, Mg) ・8Al2O3 :E
u5ZnO: Zn, Zn2SiO4: Mn, Zn2
Ge04: Mn, yvo4: EuXY2O2
S: Eu, 0.5MgF2 ・3.5MgO-Ge
Examples include oxyacid salts such as O2:Mn, or at least one of these may be used.

Next, the thermal transfer recording sheet of the present invention is characterized in that it is combined with a thermal transfer image-receiving paper having a magnetic recording layer mainly composed of ferromagnetic powder coated on the opposite side of the transfer surface of the base material. That is. This thermal transfer image-receiving paper uses a magnetic head to magnetically record a specific signal on a coated magnetic recording layer, and the recording can be read by the magnetic head as needed. The magnetically recorded signals can be extracted as electrical signals to operate various automatic devices. Data can also be stored by linking with a computer. In combinations using these thermal transfer image-receiving papers, prevention of tampering is an important issue, as seen in the various applications mentioned above.

The thermal transfer image-receiving paper used in combination with the thermal transfer recording sheet of the present invention has a magnetic recording layer coated on the surface opposite to the transfer surface of the base material, and the composition of the magnetic recording layer is magnetic powder. , binder, and other additives.

As magnetic powder, 7-Fe2O3, Fe3 G4.7F
Mixed crystal of e2O3 and Fe2O4, containing Co -Fe2O3
, coo Fe, O, Ba-ferrite, Sr-ferrite, etc. are used, but Ba-ferrite and Sr-ferrite, which have higher coercive force, are preferable.

As the binder, polyester resin, vinyl chloride resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylonitrile copolymer, styrene-butadiene copolymer, polyacrylic acid ester resin,
Epoxy resin, nitrocellulose, etc. are used.

As other additives, plasticizers, lubricants, antistatic agents, pigments, etc. are used as necessary.

The base material used in the thermal transfer recording sheet of the present invention includes polyester film, polycarbonate film, polypropylene film, polyimide film, acetate film, polyethylene film, and the like. Its thickness is 3-16 μm, preferably 4-JO μm. A heat-resistant layer may be coated on the base material, or the heat-resistant layer may not be provided as long as the base material can withstand a thermal head.

Hot-melt ink is composed of colorants, waxes, and resins.

As the coloring agent, carbon black is used in the present invention. However, for colors, for example, yellow, benzidine yellow G, magenta, rhodamine lake Y, cyan, phthalocyanine blue, etc. may be used.

As waxes, for example, paraffin wax, carnauba wax, low molecular weight polyethylene wax, oxidized polyethylene wax, synthetic wax, etc. are used.

As the resin, for example, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer fatty acid hydrocarbon resin, aromatic hydrocarbon resin, etc. are used.

A heat-resistant agent is used for the heat-resistant layer coated on one side of the base material, and silicone resin, epoxy resin, melamine resin, phenol resin, fluororesin, polyimide resin, nitrocellulose, etc. are used as the heat-resistant agent.

Coating of the hot melt ink is carried out using a rod coater, gravure coater, reverse roll coater, direct roll coater, etc., and by hot melt coating or solvent coating.

1 Effect] The thermal transfer recording sheet of the present invention has a heat-resistant layer on one side of the base material,
A heat-fusible ink layer is coated on the opposite side, and the heat-fusible ink layer contains an inorganic fluorescent pigment, so it can be used as a thermal transfer recording sheet that is tamper-proof. It is.

Regarding the anti-tampering property, the hot-melt ink uses carphone black as a colorant, so the recorded image is black, and the inorganic fluorescent pigment contained therein cannot be visually identified. In order to identify them, it is necessary to irradiate them with light of a specific excitation wavelength, such as a black light. That is, in normal use, the recorded image can only be seen as a black image.

In addition, in order to make it difficult to identify, the particle size of the inorganic fluorescent pigment must be 0. 5-5.0 μm and the layer thickness of the heat-melting ink layer is 2-8
This is because it is limited to a range of μm.

Furthermore, the use of inorganic fluorescent pigments improves the disadvantages of conventional organic fluorescent pigments in terms of heat resistance, weather resistance, and the like.

For the above reasons, the thermal transfer recording sheet of the present invention has an effect not seen in the prior art.

[Example] The present invention will be specifically described below with reference to Examples.

Example 1 A heat resistant agent consisting of 10 parts by weight of a 50% xylene solution of silicone resin and 1 part by weight of an organic acid metal salt as a curing agent was coated on one side of a 6 μm polyester film (width 550 mm) using a gravure coater, and the thickness was A heat-resistant layer with a thickness of 0.5 μm was obtained.

Subsequently, a heat-melting ink having the following formulation was coated at 3 g/rrf using a hot-melt coater on the opposite side to the side on which the heat-resistant layer was applied, to prepare a thermal transfer recording sheet.

The inorganic fluorescent pigment used here is a white powder with a particle size of 2.2 μm, a maximum emission wavelength of 624 nm, and a red emission color, and its composition is Y, O, S: Eu. be.

(Formulation of heat-melting ink) Carbon black 15 parts by weight Black dye
5 parts by weight inorganic fluorescent pigment
5 parts by weight Paraffin wax 35 parts by weight Carnauba wax 30 parts by weight Ethylene acetate resin
10 parts by weight Regarding the thermal transfer recording sheet obtained above, thermal transfer receiving paper (manufactured by Mitsubishi Paper Mills, thermal transfer receiving paper TT) was used.
RT) and printed using a thermal printing device (manufactured by Matsushita Electronic Components). The recorded image printed on the thermal transfer receiver paper could only be identified as black under visible light. Subsequently, this printed sample was illuminated in a dark room using a fluorescent inspection lamp (manufactured by Tokyo Kogakuki Co., Ltd., model Fl-38), and a bright red recorded image could be identified.

Examples 2 to 4 and Comparative Example 1 Thermal transfer recording sheets were prepared and evaluated in the same manner as in Example 1, except that the amounts of inorganic fluorescent pigment and paraffin wax were changed in the formulation of the heat-melting ink of Example 1. . The results are listed in Table 1.

(Leaving space below) Table 1 *Fluorescence: Identification in a dark room using a fluorescent inspection lamp ○...Identification is good △...Identification is somewhat good ×...Identification is difficult Example 6 Heat of Example 1 A thermal transfer recording sheet was prepared and evaluated in the same manner as in Example 1, except that the composition of the meltable ink was changed as follows.

(Formulation of heat-melting ink) Carbon black 15 parts by weight Black dye
5 parts by weight inorganic fluorescent pigment 4
0 parts by weight Paraffin wax 20 parts by weight Carnauba wax 10 parts by weight Ethylene vinyl acetate resin
The recorded image on the 10 parts by weight thermal transfer image receiving paper was slightly grayish, but within an acceptable range.

The evaluation results in a dark room were good, as bright red could be discerned.

Comparative Example 2 A thermal transfer recording sheet was prepared and evaluated in the same manner as in Example 1, except that the formulation of the heat-melting ink in Example 1 was changed as follows.

(Formulation of heat-melting ink) Carbon black 15 parts by weight Black dye
5 parts by weight inorganic fluorescent pigment 4
5 parts by weight Paraffin wax 15 parts by weight Carnauba wax 10 parts by weight Ethylene vinyl acetate resin
The results of the evaluation in a dark room at 10 parts by weight were good as a bright red color could be discerned, but the recorded image on the thermal transfer receiver paper was gray and unsuitable for practical use. Furthermore, the ink was easily peeled off from the base material.

Example 7 Instead of the inorganic fluorescent pigment with a red luminescent color used in Example 1, a white powder with a particle size of 3.0 μm and a maximum luminescent wavelength of 5 were used.
34 nm, green emission color, and its composition is Zn2G
e4: A thermal transfer recording sheet was prepared and evaluated in the same manner as in Example 1, except that instead of using Mn, a thermal transfer image receiving paper having a magnetic recording layer coated on the surface opposite to the transfer surface was used.

As a result of the evaluation in a dark room, it was possible to distinguish a bright green color. Furthermore, the recorded image could only be identified as black under visible light.

Comparative Example 3 A thermal transfer recording sheet was prepared in the same manner as in Example 7 except that an inorganic fluorescent pigment with a particle size of 6.0 μm was used instead of the inorganic fluorescent pigment with a particle size of 6.0 μm used in Example 7. .

On the surface of the heat-melting ink layer of the prepared thermal transfer recording sheet, white inorganic fluorescent pigment could be seen as dots when viewed under visible light. This was caused by the fact that the particle diameter was large relative to the thickness of the heat-melting ink layer.

[Effects of the Invention] When the thermal transfer recording sheet of the present invention is printed on a thermal transfer receiver paper, the resulting recorded image can be identified as normal black under visible light, but when a specific excitation wavelength such as black light When irradiated with light, it is possible to identify the color of the emitted light depending on the type of inorganic fluorescent pigment, and it has the effect of preventing tampering, so it has extremely high practical value.

Claims (1)

[Claims] 1. A thermal transfer recording sheet comprising a heat-resistant layer coated on one side of a base material and a heat-melting ink layer coated on the opposite side,
The heat-melting ink is mainly composed of carbon black, waxes, and resins, and further contains 400 to 700 nm.
1. A thermal transfer recording sheet comprising a white or pale white inorganic fluorescent pigment having a maximum emission wavelength of m and a particle size of 0.5 to 5.0 μm. 2. The inorganic fluorescent pigment is CaS:Bi, SrS:Sm:
Ce, ZnS:Ag, ZnS:Cu, ZnS:Cu:C
Sulfide system consisting of o, Sr_5(PO_4)_3Cl:
Eu, 3(Ba, Mg)・8Al_2O_3: Eu, Z
nO: Zn, Zn_2SiO_4: Mn, Zn_2Ge
O_4: Mn, YVO_4: Eu, Y_2O_2S: E
u, 0.5MgF_2・3.5MgO・GeO_2:M
2. The thermal transfer recording sheet according to claim 1, wherein the thermal transfer recording sheet is at least one type of oxyacid salt consisting of n. 3. The amount of inorganic fluorescent pigment in the heat-melting ink is 0.5 to 4.
The thermal transfer recording sheet according to claim 1, wherein the thermal transfer recording sheet contains 0% by weight. 4. In a thermal transfer recording sheet formed by coating a heat-resistant layer on one side of a base material and coating a heat-melting ink layer on the opposite side,
The heat-melting ink is mainly composed of carbon black, waxes, and resins, and further contains 400 to 700 nm.
What is a thermal transfer recording sheet and a transfer surface of a base material, which are characterized by containing a white or pale white inorganic fluorescent pigment having a maximum emission wavelength of m and a particle size of 0.5 to 5.0 μm? A thermal transfer recording sheet consisting of a thermal transfer image-receiving paper coated with a magnetic recording layer mainly composed of ferromagnetic powder on the opposite side. 5. The inorganic fluorescent pigment is CaS:Bi, SrS:Sm:
Ce, ZnS:Ag, ZnS:Cu, ZnS:Cu:C
Sulfide system consisting of o, Sr_5(PO_4)_3Cl:
Eu, 3(Ba, Mg)・8Al_2O_3: Eu, Z
nO: Zn, Zn_2SiO_4: Mn, Zn_2Ge
O_4: Mn, YVO_4: Eu, Y_2O_2S: E
u, 0.5MgF_2・3.5MgO・GeO_2:M
5. The thermal transfer recording sheet according to claim 4, wherein the thermal transfer recording sheet is at least one type of oxyacid salt consisting of n. 6. The amount of inorganic fluorescent pigment in the heat-melting ink is 0.5 to 4.
5. The thermal transfer recording sheet according to claim 4, wherein the thermal transfer recording sheet contains 0% by weight. 7. The thermal transfer recording according to claim 4, wherein in the combination of a thermal transfer recording sheet and a thermal transfer image-receiving paper, the magnetic powder of the magnetic recording layer coated on the thermal transfer image-receiving paper is composed of Ba-ferrite and Sr-ferrite. sheet.