JP2588178B2 - Thermal transfer media that changes color with temperature - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive transfer medium which changes color due to a temperature change used in a heat-sensitive transfer device such as a printer, a facsimile, and the like. The present invention relates to a heat-sensitive transfer medium whose color changes by being heated by some heat source after transfer recording by the above-mentioned heat-sensitive transfer device.

[Prior Art] Conventionally, a thermal transfer medium has been provided with a heat-meltable ink layer which is heat-melted at a predetermined temperature on a base film having a thickness of, for example, about 3 to 12 μm.

To explain the recording operation of this thermal transfer medium, a thermal head is in contact with the base film, and when the thermal head is driven according to a recording signal and generates heat, the heat-meltable ink of the corresponding portion of the base film is heated. Is melted and transferred to the receiving paper. A transfer image corresponding to the recording signal is formed on the transfer paper by the transfer ink, and recording on the transfer paper using plain paper can be performed.

However, since the thermal transfer medium as described above uses a mixture of a pigment such as carbon black and the like in a heat-meltable wax and the like for the heat-meltable ink layer, the transfer image formed on the surface of the transfer-receiving paper is used. The recording was limited to the color of the pigment used in the heat-meltable ink layer, and recording of a transferred image or the like that changed color with a change in temperature was impossible at all.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a heat-sensitive transfer medium capable of recording a transfer image having a property of changing color by an extremely good temperature change.

[Constitution of the Invention] That is, the present invention is characterized in that at least a transfer layer which changes color by a temperature change containing a temperature-indicating pigment is formed directly or via a release agent layer on a base film. The present invention relates to a heat-sensitive transfer medium which changes its color due to heat.

That is, in the present invention, at least in place of the heat-meltable ink layer of the conventional thermal transfer medium, at least by using a transfer layer containing a thermochromic pigment, the color of which changes due to a temperature change, the property of changing the color by an extremely good temperature change. This completes a heat-sensitive transfer medium that changes color due to a temperature change at which a transferred image such as a character, an illustration, and a map can be recorded.

That is, according to the present invention, at least a transfer layer (3) which changes color by a temperature change containing a thermochromic pigment is formed directly or via a release agent layer (2) on a base film (1). Accordingly, it is possible to provide a heat-sensitive transfer medium that changes color by temperature change, which enables recording of a transferred image such as a character, an illustration, and a map that changes color due to a very good temperature change.

As the base film (1) in the thermal transfer medium of the present invention, which changes its color by a change in temperature, any base film having sufficient self-holding properties can be used. Examples thereof include polyester, polyamide, polyamideimide, polyethylene, polypropylene, and cellulose. Resins such as acetate, polycarbonate, polyvinyl chloride, and fluororesin, or film-like or sheet-like material such as cellophane paper and glassine paper, release paper or release film are appropriately used. In particular, as the base film (1), a film-like material of the above-mentioned resins having a thickness of about 5 to 12 μm is used, and the production of a heat-sensitive transfer medium which changes color by a temperature change without wrinkles or cracks is continuously carried out. It is preferable because it can be mass-produced. The invention previously filed by the applicant (Japanese Patent Application No. 60-26)
No. 0774), a thin film of an inorganic material on the side opposite to the side on which the thermal transfer layer of the plastic film is provided, for example,
_{SiO, SiO 2, TiO 2,} ZnO, oxides such as Al ₂ O _3, nitrides such as TiN, carbides TiC, etc., carbon, Al, Ni, Cr, Tr , Ni-Cr
A hot-stick resistant material provided with a thin film of about 6 to 100 nm of a metal such as an alloy is also preferably used.

If the base film (1) does not have good releasability from the transfer layer (3) or the protective resin coating layer (31) whose color changes due to temperature change, paraffin wax, silicone,
Release agent layer by applying fluororesin, surfactant, etc. (2)
May be formed.

The transfer layer (3) of the present invention, which changes color by temperature change,
It is applied and formed on the base film (1) directly or via the release agent layer (2) by an ordinary method. For example, an ink or a coating composition containing a thermochromic pigment can be used as the coating material that changes color according to the temperature change that forms the transfer layer that changes color according to the temperature change, and specifically, for example, mercuric iodide A thermochromic pigment or a thermochromic pigment composition which causes a discoloration phenomenon in a target temperature range by optionally mixing one or more of a reversible thermochromic pigment containing a complex salt and an irreversible thermochromic pigment containing cobalt hexamethylenetetramine bromide. (Refers to a mixture of thermochromic pigments, hereinafter the same),
Next, if the temperature-indicating pigment or the composition obtained above is required, a conventional dye or pigment together with a conventional vehicle for an ink or coating composition, for example, spermaceti, beeswax, lanolin, carnauba wax, candelilla wax, montan wax, etc. Natural wax, paraffin wax, microcrystalline wax, oxidized wax, ester wax, synthetic wax such as low molecular weight polyethylene, lauric acid, myristic acid, palmitic acid, stearic acid, fromamic acid,
Higher fatty acids such as behenic acid, stearyl alcohol, higher alcohols such as behenyl alcohol, fatty acid esters of sucrose, esters such as fatty acid esters of sorbitan, amides such as stearinamide and oleinamide;
Polyamide resin, polyester resin, epoxy resin, polyurethane resin, acrylic resin, vinyl chloride resin, cellulose resin, polyvinyl resin, petroleum resin, ethylene-vinyl acetate copolymer resin, phenol resin , Styrene resin, natural rubber, styrene butadiene rubber, isoprene rubber, chloroprene rubber and other elastomers, rosin and its derivatives, terpene resin, hydrogenated petroleum and other tackifiers, fillers, plasticizers, antioxidants, etc. A paint which changes color by a change in temperature, which is composed of one or a mixture thereof, is preferably used.

In the above description, as the reversible thermochromic pigment, known pigments, for example, those represented by formulas such as Ag _x Cu _2-x HgI ₄ (where X <2) M ₂ [HgI ₄ ] (where M is a monovalent metal) Can be used. As the irreversible temperature indicator pigment, a known example _{CoI 2 .C 6 H 12 N 4} · 10H 2 OK 3 [Co (C 2 O 4) 3] · 3H 2 OK 3 [Cr (C 2 O 4) 3 _{] · 3H 2 O Ba 3 [} Fe (C 2 O 4) 3] 2 · 3H 2 O 3 (NH 4) 2 O · Al 2 O 3 · 12MoO 3 · 19H 2 O 3 (NH 4) 2 O · Fe ₂ O ₃ · 12MoO ₃ · 19H ₂ O 3 (NH ₄ ) ₂ O · Cr ₂ O ₃ · 12 MoO ₃ · 2OH ₂ O 3 (NH ₄ ) ₂ O · TiO ₂ · 12 MoO ₃ · 10H ₂ O 4 (NH _{4 ) 2 O · Mn 2 O 3} · 12MoO 3 · 9H 2 O 6 (NH 4) can be used _{2 O · 3NiO · 16MoO 3 ·} 29H 2 O and the like.

In the temperature indicating ink or coating composition of the present invention, the mixing ratio of the temperature indicating pigment or the composition is based on 100 parts (parts by weight, hereinafter the same) of the vehicle for the ink or the coating composition as described above. A mixing ratio of about 5 to 100 parts is preferable.

The thickness of the transfer layer (3), which changes its color by a change in temperature, is about 0.5 to 100 μm. 0.5μ
If the thickness is less than m, it is possible to obtain a heat-sensitive transfer medium that changes color due to a temperature change that is physically and chemically stable, such as surface strength, acid resistance, and alkali resistance, as well as a property that changes color due to a sufficiently stable temperature change. When the thickness is more than 100 μm, it is difficult to transfer and form a pattern such as a delicate character pattern, so that it is not preferable for transferring a pattern such as a fine character pattern.

The formation of the temperature-indicating ink composition coating layer as the transfer layer (3), which changes color by a temperature change, is performed by using an organic solvent solution, an aqueous solution, or the like of the temperature-indicating ink or the coating composition, by a roll coating method, a gravure coating method, a reverse coating method, or the like. It is performed by applying by a normal coating method such as a spray coating method and drying (curing in the case of a thermosetting resin, an electron beam curable resin, an ultraviolet curable resin or the like).

In the heat-sensitive transfer medium of the present invention, which changes its color due to a change in temperature, the transfer layer itself, which changes its color due to a change in temperature, has low mechanical strength and is easily damaged by friction. Mold layer (2)
In some cases, a protective resin coating layer (31) may be provided beforehand. The thickness of the protective resin coating is not particularly limited, but is usually 0.5 to
It is appropriately selected from the range of 2 μm.

As the resin for forming the protective resin coating layer (31), for example, any of a thermoplastic resin, a thermosetting resin, an electron beam curable resin, and an ultraviolet curable resin is used. Vinyl chloride-vinyl acetate copolymer,
Polyvinyl butyral, polycarbonate, nitrocellulose, cellulose acetate, urethane resin, urea resin, melamine resin, urea-melamine resin, epoxy resin, alkyd resin, amino alkyd resin, rosin-modified maleic resin, etc. Alternatively, a mixture is preferably used.

The protective resin layer is formed by applying an organic solvent solution of the resin for forming the protective resin coating film, an aqueous solution, or the like by a normal coating method such as a roll coating method, a gravure coating method, a reverse coating method, and a spray coating method. And drying (in the case of a thermosetting resin, an electron beam curable resin, an ultraviolet curable resin, etc., curing).

The protective resin layer may be colored with a coloring material such as a dye or a pigment as long as it is transparent or translucent.

In the heat-sensitive transfer medium of the present invention, which changes its color by a change in temperature, for example, a metal such as aluminum, tin, zinc, copper, silver, gold, nickel, chromium, titanium, or the like, is formed on the coating layer of the temperature-sensitive ink by a conventional method. An alloy can be deposited to form a metal deposition layer (32).
With this, in the present invention, the color change due to the temperature change of the thermochromic pigment and the reflection effect of the metal deposition film can be simultaneously exhibited.

Further, in the thermal transfer medium of the present invention, which changes its color by a change in temperature, a normal printing method or a black or dark blue color ink or a coating composition is used on the temperature indicating ink composition coating layer by a conventional method. A colored layer (32) such as black or dark blue can be formed by a coating method or the like. With this, the temperature indicator pigment expresses a color change by a characteristic of selectively reflecting light of a specific wavelength at a specific temperature and absorbing light of another wavelength, so that the color change can be made more vivid. is there.

In the heat-sensitive transfer medium of the present invention, which changes its color by a change in temperature, the transfer layer, which changes its color by changing the temperature, is used in order to strongly increase the mechanical strength of the transfer layer itself, which changes its color due to a change in temperature, so as not to be easily damaged by friction. It can be improved by using resin as the main component of the paint that changes color due to temperature change for forming, but the transfer rate to the transfer paper and the transfer strength tend to be inferior, so the color change due to temperature change The adhesive layer (33) may be provided on the surface of the transfer layer to be formed.

Examples of the adhesive layer (33) of the heat-sensitive transfer medium which changes its color by a change in temperature according to the present invention include natural waxes such as spermaceti, beeswax, lanolin, carnauba wax, candelilla wax, montan wax, paraffin wax, microcrystalline wax, and the like. Oxidized wax, ester wax, synthetic wax such as low molecular weight polyethylene, higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, furomenic acid, behenic acid, higher alcohols such as stearyl alcohol and behenyl alcohol, and fatty acid esters of sucrose , Esters such as fatty acid esters of sorbitan, amides such as stearinamide and oleinamide, polyamide resins, polyester resins, epoxy resins, polyurethane resins, acrylic resins, vinyl chloride resins Cellulose resin, polyvinyl resin, petroleum resin, ethylene-vinyl acetate copolymer resin, phenol resin, styrene resin, natural rubber, styrene butadiene rubber, isoprene rubber, chloroprene rubber and other elastomers, rosin and the like Tackifiers such as derivatives, terpene resins, hydrogenated petroleum resins, etc., fillers, plasticizers, antioxidants, etc., alone or in combination may be used. As long as it is transparent or translucent, the adhesive layer may be added with a pigment which changes its color due to the previous temperature change in order to enhance the effect of changing its color due to the temperature change of the entire thermal transfer medium. Adhesive layer (33)
The thickness of the paper is appropriately selected and determined according to the surface condition of the paper to be transferred, but is usually selected from a range of about 1 to 100 μm. It is as thin as about 1 to 2 μm.

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

EXAMPLES Example 1 Reversible thermochromic pigment 2 which is Ag _x Cu _2-x HgI ₄ (where X = 1.6)
0 parts, paraffin wax 50 parts, carnauba wax 25
, A composition consisting of 15 parts of an ester wax and 10 parts of an ethylene-vinyl acetate copolymer resin was sufficiently kneaded to prepare a thermosetting ink composition. Next, this temperature-indicating ink composition is hot-melt coated on a polyethylene terephthalate film having a thickness of 6 μm to form a transfer layer having a thickness of 5 μm, which changes its color according to a temperature change. I got

Example 2 A coating solution comprising 20 parts of ester wax dissolved in a mixed solvent consisting of 60 parts of toluene and 20 parts of petroleum naphtha was applied on a 6 μm-thick polyethylene terephthalate film and dried to form a 1 μm-thick release agent layer. Is formed on the surface, and 10 parts of irreversible thermal pigment K ₃ [Co (C ₂ O ₄ ) ₃ ] .3H ₂ O, 50 parts of paraffin wax, 25 parts of carnauba wax, 15 parts of ester wax and ethylene -A temperature indicating ink composition prepared by thoroughly kneading 10 parts of a vinyl acetate copolymer resin with a mixed solvent consisting of 60 parts of toluene and 20 parts of petroleum naphtha was coated on a 6 μm-thick polyethylene terephthalate film and dried. Thus, a transfer layer having a thickness of 5 μm and changing its color by a change in temperature was formed to obtain a heat-sensitive transfer medium of the present invention which changed its color by a change in temperature.

Example 3 A temperature indicator obtained by sufficiently kneading 20 parts of the same reversible thermochromic pigment as used in Example 1, 50 parts of ester wax and 50 parts of carnauba wax on a polyethylene terephthalate film having a thickness of 12 μm. The ink composition is applied and dried to form a transfer layer having a thickness of 3 μm, which changes color due to a change in temperature, and then a 50-nm-thick metal-deposited layer is formed on the surface by depositing aluminum by a vacuum deposition method. Further, a coating solution obtained by dissolving 20 parts of paraffin wax, 5 parts of carnauba wax, and 5 parts of ethylene-vinyl acetate copolymer resin in a mixed solvent consisting of 60 parts of toluene and 20 parts of turpentine oil is applied to the surface and dried. An adhesive layer having a thickness of 2 μm was formed to obtain a heat-sensitive transfer medium of the present invention, which changes its color by a change in temperature.

[Effects of the Invention] Thermal transfer printer Canon C-4253 (manufactured by Canon Inc.) on plain paper using the thermal transfer medium that changes color with temperature change obtained in Example 1, Example 2 and Example 3.
Printed with.

The resulting images of characters, illustrations, maps, etc. on plain paper were well transferred and recorded even in extremely delicate portions, and furthermore, reversibly or irreversibly changed to their respective hues due to temperature changes.

Incidentally, those of Examples 1 and 3 reversibly changed color from reddish yellow to yellowish orange at 40 ° C. In Example 2, the color was irreversibly changed from dark blue-green to light red-purple at 128 ° C.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a basic structure of a thermal transfer medium of the present invention which changes color by a change in temperature, and FIG. 2 shows another embodiment of a thermal transfer medium of the present invention which changes color by a change in temperature. It is sectional drawing. (1): Base film (2): Release agent layer (31): Protective resin layer (3): Transfer layer that changes color with temperature change (32): Metal deposition layer or / and coloring layer (33): Adhesion Agent layer

Claims (5)

(57) [Claims] 1. A color change due to temperature change, characterized in that at least a transfer layer containing a thermochromic pigment and changing color by temperature change is formed on a base film directly or via a release agent layer. Thermal transfer media. 2. The heat-sensitive transfer medium according to claim 1, wherein said transfer layer, which changes its color according to a change in temperature, comprises a coating layer of a thermochromic ink composition containing a thermochromic pigment. 3. The color change by temperature change according to claim 1, wherein a protective resin coating layer is interposed between the base film or the release agent layer and the transfer layer whose color changes with temperature change. Thermal transfer media. 4. The heat-sensitive transfer medium according to claim 1, wherein an adhesive layer is further formed on the transfer layer whose color changes with the temperature change. 5. A method according to claim 1, wherein at least a protective resin coating layer, a transfer layer which changes its color according to a temperature change, and an adhesive layer are sequentially formed on the base film directly or via a release agent layer. A heat-sensitive transfer medium that changes color according to a temperature change according to claim 1.