JP2000289353A - Heat-sensitive transfer recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive transfer recording medium having a constitution in which the difference of colors between a transferred part and a non- transferred part of a color ink layer of a recording medium after the transfer of the color ink layer is too small to be sensed by a copier or to form a duplicate on the recording medium, and the printing image on the ink offset can be read visually and also used parts can be checked visually. SOLUTION: A recording body is provided with a black ink layer of thermal transfer properties through a duplicate preventing layer as a colored layer not provided with the thermal transfer properties and preventing the duplicate to be formed on one face of a base. In this case, the color of the duplicate preventing layer is different from that of the black ink layer, and the difference of colors ΔEab* between the duplicate preventing layer and the black layer when the colors of the duplicate preventing layer and the black ink layer are represented by a L*a*b* color representing system is set to 3.0-30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermal transfer recording medium.

[0002]

2. Description of the Related Art A conventional heat-sensitive transfer recording medium is generally provided with a heat-melting or heat-softening colored ink layer on a substrate. In a conventional thermal transfer recording medium of this type, a difference in color density occurs between the remaining portion of the ink and the portion from which the ink has been removed due to the loss of the ink in the portion heated and printed by the thermal head. It was possible to read information from the thermal transfer recording medium, and there was a risk of confidential leakage.

Therefore, a technique has been proposed in which an adhesion layer that does not thermally transfer is provided between the colored ink layer and the substrate, and the color of the adhesion layer is made the same as that of the colored ink layer, thereby providing a function of preventing leakage of confidential information (Japanese Patent Laid-Open No. Hei 9 (1999)). No. 7-164768). The thermal transfer recording medium of this technique was often used for facsimile.

[0004]

By the way, a received facsimile document may be discarded without making a copy. If it is desired to read this document again after discarding the received document, in the thermal transfer recording medium of the related art, the color of the ink trace and the color of the remaining portion of the colored ink are the same because the colored ink layer and the adhesion layer are the same color, It was difficult to read the contents of the prints even if they saw the print marks. Further, in the above-mentioned conventional technology, since the colored ink layer and the adhesion layer are of the same color, it is difficult to confirm that the used thermal transfer recording medium has been used even if it has been used once. There was a problem of doing. When the used thermal transfer recording medium is used again, the printed image becomes unclear and cannot be read. In particular, when used in a facsimile, reprinting cannot be performed just because the image is unclear, and there is a problem that a transmission request must be sent to the transmission source again.

In order to solve the problems of the conventional heat-sensitive transfer recording medium, the present inventors made the colored ink layer and the adhesion layer different colors, so that the contents could be visually read from the print traces.
After examining ways to make it easier to confirm that a product has been used once, it has been found that a device that can read information visually from the traces of printing can be copied easily with an electrophotographic copying machine. did. Since the spread of confidentiality becomes extremely large when copying is possible, the prevention of copying is extremely important in preventing the spread of confidentiality.

The present invention has been made in view of the above-mentioned problems of the prior art,
Make sure that the thermal transfer recording medium after printing has the function of preventing copying by a copying machine, and that the thermal transfer recording medium can be read with the used thermal transfer recording medium, and that the thermal transfer recording medium has been used. It is an object of the present invention to provide a thermal transfer recording medium having a function that can be easily confirmed visually and can prevent reuse.

[0007]

According to the present invention, there is provided a black ink layer having no heat transfer property on one side of a base material and a heat transferable black ink layer via a copy prevention layer which is a colored layer for preventing copying. In the thermal transfer recording medium provided, when the copy protection layer has a different color from the black ink layer, and the colors of the copy protection layer and the black ink layer are represented by an L ^* a ^* b ^* color system. Wherein the color difference ΔEab ^* between the anti-copy layer and the black ink layer is 3.0 to 30.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The thermal transfer recording medium of the present invention has no thermal transferability, and has a structure in which a copy-preventing layer, which is a colored layer for preventing copying, is provided. Since the color difference between the black ink-transferred part and the black ink-untransferred part of the recording medium after printing is so small that it cannot be detected by a copying machine, a copy of sufficient quality that can be read even if a copy is attempted. Cannot be obtained. On the other hand, by making the color of the copy prevention layer and that of the black ink layer different from each other, it becomes possible to visually read the print from the print trace of the thermal transfer recording medium. That is, by storing the used heat-sensitive transfer recording medium, the recording can be stored. At this time, it is easy to confirm that the thermal transfer recording medium has been used, and it is possible to prevent the used thermal transfer recording medium from being reused by mistake.

In the present invention, the color difference between the copy prevention layer and the black ink layer is ΔEab ^* = 3.0 to 30, preferably ΔEab ^* = 3.0 to 30.
Eab ^* = 5.0-25. If the color difference ΔEab ^* between the anti-copy layer and the black ink layer is less than the above range, it is difficult to read the trace of printing on the thermal transfer recording medium, which is not preferable.
On the other hand, if the color difference ΔEab ^* between the copy protection layer and the black ink layer exceeds the above range, the copy protection function of the copying machine is not provided, which is not preferable. Further, since the traces of the thermal transfer recording medium are different in color from the black ink, it is easy to visually check the traces of printing on the thermal transfer recording medium, and easily whether the thermal transfer recording medium has been used. Understand and prevent re-use by mistake.

The color difference between the copy preventing layer and the black ink layer is ΔE
Means for setting ab ^* = 3.0 to 30 are not particularly limited. A colorant having a hue other than black may be used as a main colorant in the copy prevention layer. The hue of the copy prevention layer may be, for example, brown, green, blue, or red. As the coloring agent, organic and inorganic coloring pigments and dyes generally used in this type of thermal transfer ink layer can be used.

The anti-copying layer according to the present invention comprises the above-mentioned coloring agent and a resin as a vehicle. As long as the anti-copying layer is not peeled off from the substrate by the heat of a thermal head or the like, a general resin may be used. Can be used without particular limitation. Examples of the resin (including an elastomer) include an ethylene-vinyl acetate copolymer, an ethylene-vinyl butyrate copolymer, an ethylene- (meth) acrylic acid copolymer,
Ethylene copolymers such as ethylene-alkyl (meth) acrylate copolymers, vinyl chloride copolymers such as (meth) acrylate resins, vinyl chloride-vinyl acetate copolymers, and vinyl chloride-vinyl alcohol copolymers (Co) polymer, polyester resin, polyamide resin, epoxy resin, phenol resin, acetophenone-formaldehyde resin, cellulose resin, natural rubber, styrene-butadiene copolymer, isoprene polymer, chloroprene polymer, petroleum Resin, styrene resin, rosin resin, terpene resin, cumarone-indene resin and the like. These resins may be used alone or in combination of two or more.

In the present invention, inorganic particles and / or organic particles can be added to the anti-copying layer in order to prevent the gloss of the transferred image. The average size of these particles is 0.5 to 10 μm, preferably 1 to 5 μm. If the average particle size is smaller than this range, the effect as a gloss inhibitor tends not to be sufficiently exhibited. On the other hand, if it is larger than this range, the thermal transferable black ink layer tends to be uneven, and the transferred image tends to be adversely affected by voids or the like.

The anti-copying layer may contain a conductive powder or an antistatic agent for preventing generation of static electricity. As the conductive powder, metal powders such as iron, copper, aluminum, gold, silver, and nickel, oxides of these metal powders, and carbon black can be used. As the antistatic agent, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant and the like can be used.

As the black ink layer in the present invention, a conventionally known heat transfer black ink layer comprising a heat-meltable or heat-softening vehicle and a black colorant can be used without any particular limitation. Examples of the vehicle include conventionally known thermoplastic resins and / or waxes.

The thermoplastic resin (including an elastomer)
As the resin, the resins exemplified in the copy prevention layer can be used. Examples of waxes include lanolin,
Natural waxes such as carnauba wax, candelilla wax, montan wax, and ceresin wax; petroleum waxes such as paraffin wax and microcrystalline wax; oxidized wax, synthetic ester wax,
Examples thereof include synthetic waxes such as polyethylene wax, α-olefin-maleic anhydride copolymer wax, urethanized wax, Fischer-Tropsch wax, and synthetic petroleum wax. These waxes may be used alone or in combination of two or more.

Examples of the black colorant include carbon black and organic and inorganic color pigments and dyes generally used in this type of thermal transfer ink layer. The content of the colorant in the ink layer is from 20 to 80.
A suitable amount is about weight%.

[0017] In addition to the above components, a curing agent, a plasticizer, a pigment dispersant, and the like can be appropriately added to the copy preventing layer and the black ink layer, if necessary.

The anti-copy layer and the black ink layer are prepared by dissolving or dispersing the above-mentioned vehicle components in an appropriate solvent (including water) (including an aqueous dispersion or emulsion), and adding a colorant and, if necessary, other compounding agents. Can be formed by applying and drying a coating solution to which is added a base material. The black ink layer can also be formed by a hot melt coating method. The coating amount of each layer (solid content converted value, the same applies hereinafter) is suitably about 0.1 to 8 g / m ^{2 in} terms of transfer sensitivity and image density.

As the substrate in the thermal transfer recording medium of the present invention, various plastic films such as a polyethylene terephthalate film can be used. The thickness of the substrate is usually about 1 to 10 μm, and preferably 1 to 6 μm from the viewpoint of reducing heat diffusion and increasing resolution.

When the thermal transfer recording medium of the present invention is used in an image forming apparatus equipped with a thermal head, a stick preventing layer may be provided on the back surface of the substrate (the surface that is in sliding contact with the thermal head). . Examples of the material for the stick prevention layer include various heat-resistant resins such as silicone resin, fluorine resin, nitrocellulose resin, or silicone-modified urethane resin and silicone-modified acrylic resin modified with these, or these heat-resistant resins. What mixed a lubricant etc. can be used suitably.

The thermal transfer recording medium of the present invention can be applied to a case where a heat source other than a thermal head is used as a heat source for thermal transfer. For example, a laser or the like can be used as a heat source.

[0022]

Next, the present invention will be described more specifically with reference to examples.

Example 1 A coating liquid having the following composition was applied by gravure coating to a surface of a 6 μm-thick polyethylene terephthalate film having a stick prevention layer made of a silicone resin formed on one side and opposite to the stick prevention layer. An anti-copying layer having an amount of 1.0 g / m ² was formed.

Coating solution for anti-copying layer component Component parts by weight Polyester resin (softening point 165 ° C.) 30 Cyan pigment (Cyanine Blue KRO) 10 Magenta pigment (Brilliant Carmine 6B307) 10 Toluene 20 Methyl ethyl ketone 30

An ink having the following composition was hot-melt coated on the anti-copying layer to form a black ink layer having a coating amount of 6.0 g / m ² , thereby obtaining a thermal transfer recording medium.

Ink layer composition component parts by weight paraffin wax (melting point 69 ° C.) 75 ethylene-vinyl acetate copolymer (softening point 35 ° C.) 5 carbon black 20

Example 2 A heat-sensitive transfer recording medium was obtained in the same manner as in Example 1, except that the following coating composition was used as the coating liquid for the anti-copying layer.

Coating solution for anti-copying layer (coating amount: 1.0 g / m ² ) Component weight part Polyester resin (softening point: 165 ° C.) 30 Brown pigment (FL brown) 20 Toluene 20 Methyl ethyl ketone 30

Comparative Example 1 A heat-sensitive transfer recording medium was obtained in the same manner as in Example 1, except that the following coating composition was used as the coating solution for the anti-copy layer.

Coating liquid for anti-copying layer (coating amount: 1.0 g / m ² ) Component weight part Polyester resin (softening point: 165 ° C.) 45 Carbon black 5 Toluene 20 Methyl ethyl ketone 30

Comparative Example 2 A heat-sensitive transfer recording medium was obtained in the same manner as in Example 1, except that the following coating composition was used as the coating liquid for the anti-copying layer.

Coating liquid for anti-copying layer (coating amount: 1.0 g / m ² ) Component weight part Polyester resin (softening point: 165 ° C.) 25 carbon black 25 toluene 20 methyl ethyl ketone 30

Comparative Example 3 A heat-sensitive transfer recording medium was obtained in the same manner as in Example 1, except that the following coating composition was used as the coating liquid for the anti-copy layer.

Coating liquid for anti-copying layer (coating amount: 1.0 g / m ² ) Component weight part Polyester resin (softening point: 165 ° C.) 25 Yellow pigment (pigment yellow 1705) 25 Toluene 20 Methyl ethyl ketone 30

The following tests were performed on each of the thermal transfer recording media obtained above. Table 1 shows the results.

(1) Copy prevention function Thermal transfer facsimile machine (UX-F1 manufactured by Sharp Corporation)
CL) on the receiving paper (Tokuhyo Rishi, manufactured by Mitsubishi Paper Mills)
A character pattern having a size of 6 points is printed, and the thermal transfer recording medium after printing is copied with an electrophotographic copying machine (SD-2052 manufactured by Sharp Corporation) at a copy density of 1 (set value in the copying machine, Density), the copies were visually observed, and evaluated according to the following criteria. ○ ‥‥‥ Unable to read 9-16 points of duplicated characters △ ‥‥‥ Unable to read 4-8 points of duplicated characters × ‥‥‥ Readable 3 points of duplicated characters

(2) Color difference between copy preventing layer and black ink layer The color difference ΔEab ^* between the copy preventing layer and the black ink layer was measured using a colorimeter CR-221 (manufactured by Minolta Co., Ltd.).

(3) Confirmation of Traces of Thermal Transfer Recording Medium The thermal transfer recording medium after transfer was visually observed for traces of 8-point characters and evaluated according to the following criteria. ○ ‥‥‥ Can understand characters. △ ‥‥‥ Characters are difficult to read. × ‥‥‥ Characters cannot be read.

[0039]

[Table 1]

[0040]

The thermal transfer recording medium of the present invention has a function of preventing copying by a copying machine after use, and allows a printed image to be visually recognized from ink bleeds and used to be confirmed. It is.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Seigo Kato 5-14-14 Motejima, Nishiyodogawa-ku, Osaka-shi, Osaka F-term in Fujikopian Corporation Technical Center (reference) 2C068 AA06 AA15 AA21 BB25 BD17 2H111 AA01 AA26 BA03 BA07 BA74

Claims (1)

[Claims] 1. A heat-sensitive transfer recording medium having a heat-transferable black ink layer provided on one side of a substrate without a heat transfer property and a copy-preventing layer which is a colored layer for preventing copying. When the copy protection layer is different in color from the black ink layer and the colors of the copy protection layer and the black ink layer are represented by an L ^* a ^* b ^* color system, the copy protection layer and the black ink Color difference with layer Δ
A thermal transfer recording medium, wherein Eab ^* is 3.0 to 30.