JP2003080847A - Thermal transfer sheet - Google Patents

Abstract

(57) [Summary] [Problem] A colored layer thermally transferred to a transfer object can reproduce its original hue on the transfer object without being affected by the color or pattern of the recording surface of the transfer object. And a thermal transfer sheet provided with a colored layer on a substrate, which enables clear recording. A thermal transfer sheet provided with at least a colored layer on one surface of a substrate, wherein the thermal transfer sheet is used in combination with a transfer object having a colored recording surface. The color difference between the color of the ink layer thermally transferred to the substrate and the color of the ink layer measured from the other side of the substrate before the thermal transfer is determined by the International Commission on Illumination (CIE) L ^*.
a ^* b ^* The color difference formula of the color system is 10 or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet of a melt transfer type, and more specifically, a colored layer which is thermally transferred to a transfer target without being affected by the color or pattern of the recording surface of the transfer target. However, the original hue can be reproduced on the transferred material,
The present invention relates to a thermal transfer sheet on which a colored layer is provided on a substrate, which enables clear recording.

[0002]

2. Description of the Related Art Conventionally, a coloring layer in which a coloring agent such as a pigment or a dye is dispersed in a heat-melting wax or a binder such as a resin,
Using a thermal transfer sheet supported on a base material sheet such as a plastic film, energy according to image information is applied by a heating device such as a thermal head, and the colorant is transferred together with a binder onto an image receiving sheet such as paper or a plastic sheet. A melt transfer method is known. The printed image formed by the melt transfer method has high density and excellent sharpness, and is suitable for recording binary images such as characters and line drawings.

Further, in the thermal transfer recording method of the above-mentioned melt transfer method, attribute information such as address, customer information, numbering, and bar code (variable fixed information for small lots) may be applied to various transfer objects such as labels and cards. Variable information represented by (including also) can be easily output and recorded using a computer and a thermal transfer printer. Such an output product is suitably used for many purposes as a multi-product small lot product or a recorded product each of which has variable unique information.

[0004]

However, when the color of the recording surface of the transferred material recorded in the above-mentioned thermal transfer recording method is dark, or the recording surface is provided with a pattern. Due to the influence of the recording surface (base), the hue of the color layer thermally transferred is different from its original color, and it appears as a mixed color of the color of the recording surface and the color of the colored layer. There is a problem that it becomes difficult to see or is unreadable.

Therefore, in order to solve the above problems,
INDUSTRIAL APPLICABILITY According to the present invention, a coloring layer that is thermally transferred to a transferred material can reproduce its original hue on the transferred material without being affected by the color or pattern of the recording surface of the transferred material, and clear recording can be achieved. An object of the present invention is to provide a thermal transfer sheet having a colored layer provided on a substrate.

[0006]

In order to achieve the above object, the thermal transfer sheet of the present invention is a thermal transfer sheet in which at least a coloring layer is provided on one surface of a substrate, and the thermal transfer sheet is colored. When used in combination with a transfer target having a recording surface, the color of the ink layer thermally transferred to the transfer target and the color of the ink layer measured from the other surface of the substrate before the thermal transfer. And the color difference formula of the International Commission on Illumination (CIE) L ^* a ^* b ^* color difference system is 10 or less.

Further, the thermal transfer sheet of the present invention is a thermal transfer sheet in which at least a coloring layer is provided on one surface of a base material, and the thermal transfer sheet is used in combination with an object to be transferred having a colored recording surface. In this case, the color difference between the background color of the colored recording surface and the color of the ink layer thermally transferred to the transfer target is the color difference formula of the L ^* a ^* b ^* color system of the International Commission on Illumination (CIE). And is 55 or more.

Furthermore, the thermal transfer sheet of the present invention is a thermal transfer sheet in which at least a colored layer is provided on one surface of a base material, and the thermal transfer sheet is used in combination with a transfer target having a colored recording surface. In this case, the color of the colored recording surface and the color of the ink layer thermally transferred to the transferred material are determined by [(Δa in the L ^* a ^* b ^* color system of the International Commission on Illumination (CIE)]. ^{The value of *} ) ² + (Δb ^* ) ² ] ^1/2 is 40 or more.

As described above, regarding the background color of the recording surface and the color of the ink layer thermally transferred to the transfer target, the International Commission on Illumination (C
IE) L ^* a ^* b ^* color system, the color difference by the color difference formula is 5
5 or more, or [(Δa ^* ) ² + (Δb ^* ) ² ] ^1/2
Value is 40 or more, or the color difference between the color of the ink layer thermally transferred to the transfer target and the ink layer measured from the other surface of the base material of the thermal transfer sheet is 10 or less. By defining as follows, the coloring layer thermally transferred to the transfer target can reproduce its original hue on the transfer target without being affected by the color of the recording surface of the transfer target.

It is preferable to provide a white hiding layer composed of a resin binder and one or more of titanium oxide, zinc oxide, silica, aluminum hydroxide, talc, clay and kaolinite on the above colored layer. It is easy to reproduce the original hue of the colored layer on the transferred material by hiding the colored recording surface of the transferred material more completely.

Further, it is desirable to provide an adhesive layer on the above-mentioned white hiding layer, which can improve the fixing property of the ink layer, such as a colored layer, which is thermally transferred onto the transfer-receiving member.

As another aspect of the thermal transfer sheet of the present invention,
A thermal transfer sheet in which at least a colored layer is provided on one surface of a base material, the thermal transfer sheet is thermally transferred to a transparent medium, and a medium having a colored surface is superposed on the printing surface of the thermally transferred transparent medium. When used by measuring the color of the ink layer thermally transferred to the transparent medium through the transparent medium, the color of the ink layer before superimposing the colored medium on the transparent medium printing surface side, after superimposing The color difference from the color of the ink layer of the
^{* A *} b ^* Color difference formula of 10 or less.

A thermal transfer sheet in which at least a coloring layer is provided on one surface of a base material, the thermal transfer sheet is thermally transferred to a transparent medium, and the surface of the printed surface of the thermally transferred transparent medium is colored. When the above-mentioned mediums are used by overlapping, the color difference between the printed surface and the non-printed surface, which is obtained by measuring the color of the ink layer thermally transferred to the transparent medium through the transparent medium, is L of International Commission on Illumination (CIE). ^{* A *} b ^* Color difference formula of a color system, which is 55 or more.

Further, at least one surface of the base material is attached to at least one surface.
A thermal transfer sheet provided with a color layer, said thermal transfer sheet
Heat transfer to a transparent medium,
When using a medium with a colored surface on the printed surface,
The color of the ink layer thermally transferred to the transparent medium
Printed surface and non-printed surface measured through transparent media
International Commission on Illumination (CIE) L^*a^*b^*In color system
[(Δa^*)^Two+ (Δb ^*)^Two]^1/2Value of 40 or more
It is characterized by being above.

As described above, when the thermal transfer sheet is thermally transferred to the transparent medium and the medium having a colored surface is superposed on the printed surface of the transparent medium in the previous period, the color difference between the printed surface and the non-printed surface is caused by the international illumination. The color difference formula of L ^* a ^* b ^* color system of the committee (CIE) is 55 or more, or [(Δa ^* ) ² +
The value of (Δb ^* ) ² ] ^1/2 is defined to be 40 or more, or the color of the ink layer before the color medium is superposed on the transparent medium printing surface side, and The color difference from the color of the ink layer is determined by the International Commission on Illumination (CI
By defining the color difference formula of the L ^* a ^* b ^* color system of E) so as to be 10 or less, the color layer thermally transferred to the transferred transparent medium is not affected by the color of the color medium. , Its original hue can be reproduced on a coloring medium.

When the transparent medium printed by thermal transfer to a transparent medium is used by being superimposed on a colored medium, a resin binder and titanium oxide, zinc oxide, silica are provided between the colored layer of the thermal transfer sheet and the substrate. It is preferable to provide a white hiding layer made of one or more of aluminum hydroxide, talc, clay and kaolinite, whereby the color of the colored medium overlaid on the printed portion is more completely hidden, and the colored layer is formed. It is easy to reproduce the original hue on a colored medium.

Further, it is desirable to provide an adhesive layer on the above-mentioned colored layer, whereby the fixing property of the ink layer, such as the colored layer, which is thermally transferred onto the transparent medium to be transferred can be improved.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described in detail.

FIG. 1 shows the thermal transfer sheet of the present invention.
1 illustrates an embodiment in which thermal transfer is performed on a transfer target having a colored recording surface. A thermal transfer ink layer composed of a colored layer 2 is provided on one surface of the substrate 1, and a heat-resistant layer 6 that improves the slipperiness of the thermal head and prevents sticking is provided on the other surface of the substrate 1. .

FIG. 2 shows another embodiment of the thermal transfer sheet of the present invention in which thermal transfer is carried out on a transfer target having a colored recording surface. The colored layer 2 and the white hiding layer are provided on one surface of the substrate 1. 3 is a thermal transfer ink layer, and the heat resistant layer 6 is provided on the other surface of the substrate 1.

Further, FIG. 3 shows another embodiment of the thermal transfer sheet of the present invention in which thermal transfer is carried out on a transfer object having a colored recording surface. The thermal transfer ink layer including the concealing layer 3 and the adhesive layer 4 is provided, and the heat resistant layer 6 is provided on the other surface of the substrate 1. In this case, since the adhesive layer 4 is provided on the thermal transfer sheet,
The fixability of the thermally transferred ink layer to the transferred material is improved.

FIG. 4 shows the thermal transfer sheet of the present invention.
Another embodiment in the case of performing thermal transfer to a transfer target having a colored recording surface is shown, in which a thermal transfer ink comprising a release layer 5, a coloring layer 2, a white hiding layer 3, and an adhesive layer 4 on one surface of a substrate 1. A layer is provided, and the heat resistant layer 6 is provided on the other surface of the base material 1. In this embodiment, since the release layer 5 is provided on the thermal transfer sheet, it is melted during thermal transfer to improve the releasability of the colored layer from the base material, and after transfer, at least a part is transferred together with the colored layer onto the surface of the transferred image. It is possible to improve the scratch resistance of the transferred image by imparting good slipperiness to the protective layer of the colored layer, particularly to the transferred image.

FIG. 5 shows another embodiment of the thermal transfer sheet of the present invention in which thermal transfer is performed on a transparent transfer target. The white hiding layer 3 and the coloring layer 2 are provided on one surface of the substrate 1.
The heat transfer ink layer consisting of the above is provided, and the heat resistant layer 6 is provided on the other surface of the substrate 1.

FIG. 6 shows the thermal transfer sheet of the present invention.
Another embodiment in the case of performing thermal transfer to a transparent transfer body is shown, in which a thermal transfer ink layer composed of a white hiding layer 3, a coloring layer 2 and an adhesive layer 4 is provided on one surface of the substrate 1, The heat-resistant layer 6 is provided on the other surface of the. In this case, since the adhesive layer 4 is provided on the thermal transfer sheet, the fixability of the thermally transferred ink layer to the transfer target is improved.

Further, FIG. 7 shows another embodiment of the thermal transfer sheet of the present invention in which thermal transfer is performed on a transparent transfer target, and the release layer 5 and the white hiding layer 3 are provided on one surface of the substrate 1. The thermal transfer ink layer including the colored layer 2 and the adhesive layer 4 is provided, and the heat resistant layer 6 is provided on the other surface of the substrate 1.
In this embodiment, since the release layer 5 is provided on the thermal transfer sheet,
It melts during thermal transfer to improve the releasability of the white hiding layer from the base material, and after transfer, at least a part is transferred together with the colored layer and the white hiding layer to the surface of the transferred image, and the protective layer for the colored layer and the white hiding layer. In particular, it is possible to improve the scratch resistance of the transferred image by giving the transferred image a good slip property.

The layers constituting the thermal transfer sheet of the present invention will be described in detail below.

Substrate: As the substrate 1 of the thermal transfer sheet used in the present invention, the same substrate as used in the conventional thermal transfer sheet can be used as it is, and other substrates can also be used. There is no particular limitation. Specific examples of the preferred substrate include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene,
There are nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, plastic films such as ionomers, paper such as condenser paper and paraffin paper, non-woven fabrics, etc. Good. A particularly preferred substrate is polyethylene terephthalate film. The thickness of this base material can be appropriately changed depending on the material so that its strength and thermal conductivity are appropriate.
About 10 μm is preferable.

Coloring layer: Coloring layer 2 of the thermal transfer sheet of the present invention
Is a colorant and a binder and, if necessary, an auxiliary agent such as a plasticizer, a surfactant, a lubricant, a fluidity adjusting agent, etc., and dissolved or dispersed in a solvent to obtain a coating solution. , Hot lacquer coat, gravure direct coat, gravure reverse coat, knife coat, air coat, roll coat, etc., and a thickness of 0.1 to 5 g / m ² in a dry state on the substrate, preferably 0.3 to
1.5 g / m ² is provided.

When the thickness of the dried coating film is less than 0.1 g / m ² , a uniform ink layer cannot be obtained due to the problem of film forming property, and when the thickness exceeds 5 g / m ² , When transferring the print
High energy is required, and there is a problem that printing can only be performed with a special thermal transfer printer.

As the colorant, colorants such as yellow, magenta, cyan, black and white can be appropriately selected from conventionally known dyes and pigments. However, when a thermal transfer sheet is formed without providing a white hiding layer, which will be described later, a pigment type having low transparency is preferably used as the colorant. Examples of the pigment include black pigments such as carbon black and graphite, red pigments such as red iron oxide and antimony red, yellow pigments such as ocher and zinc yellow, blue pigments such as navy blue and ultramarine, white pigments such as titanium oxide and zinc sulfide. Known inorganic pigments such as pigments can be used. In addition, benzimidazolone monoazo, quinacridone, phthalocyanine, slene, dioxazine, isoindolinone, perylene, thioindigo, pyrocholine, fluoropin,
Examples also include quinophthalone-based organic pigments. The above-mentioned inorganic or organic pigment has not only low transparency but also excellent weather resistance without fading particularly when the thermal transfer print is used for outdoor applications.

Further, in the present invention, the hue of the colored layer, which is the thermal transfer ink layer to be thermally transferred and recorded, is adjusted according to the color and the pattern of the recording surface of the transferred material to be thermally transferred. Since its hue is determined by the hue of the colorant contained in the colored layer,
From the pigments listed above, select the type that matches the desired hue. Further, the pigment is not limited to one kind, and many kinds of pigments can be added to the coloring layer as coloring agents.

The binder used in the colored layer is preferably composed mainly of a resin. Specific examples of the resin include cellulose resin, melamine resin, polyester resin, polyamide resin, polyolefin resin, acrylic resin. , Thermoplastic resins such as styrene resins, vinyl chloride-vinyl acetate copolymers and styrene-butadiene rubber. Among the resins used as the binder, polyester resins, acrylic resins, and vinyl chloride-vinyl acetate copolymers are preferably used from the viewpoints of transferability, scratch resistance, heat resistance, and the like. In addition, if necessary, a wax component may be mixed and used to the extent that heat resistance and the like are not impaired.

Examples of the wax include microcrystalline wax, carnauba wax, paraffin wax and the like. In addition, Fischer-Tropsch wax, various low molecular weight polyethylene, wood wax, beeswax, spermaceti wax, ivowa wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax, fatty acid ester, fatty acid amide, etc. Wax. Among these, those having a melting point of 50 to 85 ° C. are particularly preferable. If it is 50 ° C. or lower, there is a problem in storability, and if it is 85 ° C. or higher, printing sensitivity is insufficient.

For the above colored layer, it is preferable to use an ink composition in which the colorant is mixed in an amount of 20 to 70% by weight and the binder in an amount of 80 to 30% by weight. When the amount of the colorant is less than the above range, the coating amount must be increased in order to obtain the density, resulting in insufficient printing sensitivity. When the amount of the colorant is more than the above range, the film-forming property cannot be obtained, which causes a decrease in scratching property after printing.

White concealing layer: In the thermal transfer sheet of the present invention, the white concealing layer 3 can be provided on the colored layer. By providing this white hiding layer, the colored recording surface of the transferred material is more completely covered, and due to the effect of the recording surface (base), the hue of the thermally transferred colored layer differs from its original hue. As a result, it is possible to solve the problem that the color of the recording surface and the color of the colored layer appear as a mixed color, which makes it difficult to see the recorded information or makes it unreadable.

The white hiding layer is titanium oxide having a high hiding property,
White pigments such as zinc oxide, silica, aluminum hydroxide, talc, clay, kaolinite, body pigments such as heavy and light calcium carbonate, barium sulfate, polystyrene particles, hollow latex particles, polyolefin particles, ethylene-vinyl acetate copolymer Combined particles, plastic pigments such as ionomer particles, a binder of a thermoplastic resin or a wax, a white coating liquid prepared by dispersing in an organic solvent or water, etc. are prepared, and a solid content weight is obtained by a conventionally known coating means. The coating amount is about 0.1 to 20 g / m ² . About 0.1 to 10 parts by weight of the above-mentioned hiding agent such as a white pigment can be added to 1 part by weight of the binder.

Among the above-mentioned white pigments and other hiding agents, titanium dioxide and zinc oxide are preferably used in terms of opacity, whiteness, dispersibility and stability. The titanium dioxide may be rutile type or anatase type, and they may be used alone or in combination. Further, it may be one produced by the sulfuric acid method or one produced by the chlorine method. As titanium dioxide, surface coating treatment with an inorganic substance such as hydrous alumina treatment, hydrous silicon dioxide treatment or zinc oxide treatment, polyhydric alcohol such as trimethylolmethane, trimethylolethane, silane coupling such as methyltrimethoxysilane, etc. Agents, polysiloxanes such as polydimethylsiloxane, .epsilon.-caprolactams, and those surface-treated with compounds such as titanate coupling can be appropriately used.

Adhesive layer: In the thermal transfer sheet of the present invention, a colored layer, a white hiding layer, and an adhesive layer 4 are sequentially formed on a base material to improve the adhesiveness between the transferred material and the thermal transfer ink layer to be transferred. Can be made. This adhesive layer is mainly composed of a thermoplastic elastomer that softens and exhibits adhesiveness when heated by a thermal head, laser, etc., and waxes are used to prevent blocking when the resulting thermal transfer sheet is wound into a roll. An antiblocking agent can be added, such as amides, esters and salts of higher fatty acids, fluororesins and powders of inorganic substances. The waxes to be added include, for example, microcrystalline wax, carnauba wax, paraffin wax and the like. Furthermore, Fischer-Tropsch wax, various low molecular weight polyethylene, wood wax, beeswax, spermaceti wax, ivowa wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax,
Various waxes such as fatty acid esters and fatty acid amides can be mentioned.

As the thermoplastic elastomer, for example, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid ester copolymer (EEA), polyester resin, polyethylene, polystyrene, polypropylene, polybutene, petroleum resin, vinyl chloride resin. , Vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, vinylidene chloride resin, methacrylic resin, polyamide, polycarbonate, polyvinyl formal, polyvinyl butyral, acetyl cellulose, nitrocellulose, polyvinyl acetate, polyisobutylene, ethyl cellulose or polyacetal. In particular, a relatively low softening point conventionally used as a heat-sensitive adhesive, for example, 50 to 15
Those having a softening point of 0 ° C. are preferable.

To form the adhesive layer, the above-mentioned thermoplastic elastomer and additives are hot-melt coated or a coating solution for forming an adhesive layer, which is dissolved or dispersed in a suitable organic solvent or water, is prepared by a conventionally known hot-melt coating or hot-melt coating. A thickness of about 0.05 to 5 g / m ² is provided in a dry state by a method such as lacquer coating, gravure direct coating, gravure reverse coating, knife coating, air coating, and roll coating.

When the thickness of the dried coating film is less than 0.05 g / m ² , the adhesiveness between the material to be transferred and the thermal transfer ink layer is inferior, resulting in poor transfer during printing. Also, the thickness is 5 g / m
^When it exceeds ² , the transfer sensitivity at the time of printing is lowered and a satisfactory printing quality cannot be obtained.

Release layer: In the thermal transfer sheet of the present invention, the release layer 5 is provided between the base material and the coloring layer to melt during thermal transfer to improve the release property of the coloring layer from the base material. At least a part of the transferred image is transferred to the surface of the transferred image together with the colored layer, and the protective layer of the colored layer, particularly the transferred image, can be provided with good slipperiness, and the scratch resistance of the transferred image can be improved. For the release layer, for example, acrylic resin, silicone resin, fluororesin, silicone, or various resins modified with fluorine, which have excellent releasability, can be used, but it is preferable to use wax as a main component.

As such a wax, various waxes which are melted at the time of printing and exhibit releasability are preferable. Suitable waxes include, for example, microcrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsch wax, various low-molecular-weight polyethylene, wooden wax, beeswax, spermaceti wax, ivowa wax,
Wool wax, shellac wax, candelilla wax,
Petrolactam, partially modified wax, fatty acid ester,
Various waxes such as fatty acid amides may be mentioned. Particularly preferred waxes are microcrystalline wax and carnauba wax, which have a relatively high melting point and are difficult to dissolve in a solvent.

The release layer is a thin layer so as not to reduce the sensitivity of the thermal transfer sheet.
The thickness is preferably about 1 to ² g / m ² .

The thermal transfer sheet of the present invention comprises a colored layer and a white hiding layer described above on a base material, and optionally a release layer,
A thermal transfer ink layer with an adhesive layer is provided.

In the present invention, when the recording surface of the transferred material used in combination with the thermal transfer sheet is colored, the color of the ink layer thermally transferred to the transferred material and the other surface of the base material of the thermal transfer sheet, That is, the color difference with the ink layer measured from the surface of the substrate on which the colored layer is not provided is 10 or less in the color difference formula of the L ^* a ^* b ^* color system of the International Commission on Illumination (CIE). The heat transfer sheet has no heat resistant layer on the other surface of the base material, and the base material is a transparent sheet.

The color difference formula of the CIE L ^* a ^* b ^* color system is represented by the following formula.

The color difference between the two colors is ΔE ^* ab, the metric brightness is L, and the quantities relating to hue and saturation are a and b. The surface colors L ^* a ^* b ^* of two objects are given by (L ₁ ^* , A
₁ ^* , b ₁ ^* ) and (L ₂ ^* , a ₂ ^* , b ₂ ^* ), ΔE ^* ab = [(ΔL ^* ) ² + (Δa ^* ) ² + (Δ
b ^{*) 2] _{1/2 ΔL * = L 2 * -L}} 1 * Δa * = a 2 * -a 1 * Δb * = b 2 * -b 1 * the two colors of the color difference of Delta] E ^* ab is from 10 When it is large, the ink layer thermally transferred from the thermal transfer sheet looks different from the original color on the transfer target whose recording surface is colored, which is not preferable. As ΔE ^* ab is 10 or less and the numerical value is smaller (closer to 0), the hue of the ink layer of the original color can be reproduced on the transfer target whose recording surface is colored. is there.

In the present invention, when the recording surface of the transfer material used in combination with the thermal transfer sheet is colored, the color difference between the ground color of the recording surface and the ink layer thermally transferred to the transfer material is determined by the International Commission on Illumination. (CIE) L ^* a ^* b ^* color difference color difference formula of 55 or more.

When the color difference ΔE ^* ab between the two colors is less than 55, there is little difference between the background color of the transferred material and the color of the information recorded by thermal transfer when viewed from a distance, and the recording on the transferred material is small. Information becomes unreadable. The value of ΔE ^* ab is 5
When the value is 5 or more, the higher the value, the clearer the recorded information on the transferred material. The value of ΔE ^* ab changes depending on the color of the recording surface of the transferred material and the type of color of the ink layer (especially the colored layer) that is thermally transferred. If the value of ΔE ^* ab is 55 or more, the transferred material is The information recorded on the body can be read immediately, even from a distance.

In the present invention, a thermal transfer sheet is used in combination.
If the recording surface of the transferred material used in this way is colored, the recording
The background color of the surface and the color of the ink layer thermally transferred to the transfer target
The International Commission on Illumination (CIE) L^*a^*b^*Color system
Then, [(Δa^*)^Two+ (Δb ^*)^Two]^1/2Has a value of 4
It is 0 or more.

The surface colors a ^* b ^* of two objects are
_{^{(A 1 *, b 1 *}} ) and _{^{(a 2 *, b 2 *}} ) as a _{^{Δa * = a 2 * -a 1}} * Δb * = b 2 * -b 1 * relationship.

The above [(Δa ^* ) ² + (Δb ^* ) ² ]
^If the value of ^1/2 is less than 40, when viewed from a distance,
There is little difference between the background color of the transferred material and the color of the information recorded by thermal transfer, and the recorded information on the transferred material becomes unreadable.

When the value of [(Δa ^* ) ² + (Δb ^* ) ² ] ^1/2 is 40 or more, the color of the recording surface of the transferred material and the color of the ink layer (especially the coloring layer) to be thermally transferred. Although the readability changes depending on the type, generally speaking, the information recorded on the transferred material can be immediately read even when viewed from a distance.

Heat-resistant layer: In the present invention, when a material weak against heat is used as the base material, it is on the surface in contact with the thermal head, that is, on the side opposite to the side where the colored layer is provided on the base material. It is preferable to provide the heat-resistant layer 6 that improves the slipperiness of the thermal head and prevents sticking. The heat-resistant layer contains a heat-resistant resin and a substance acting as a thermal release agent or a lubricant as basic constituent components. By providing such a heat-resistant layer, it is possible to perform thermal transfer printing without causing sticking even on a thermal transfer sheet using a plastic film that is weak against heat as a base material, and the plastic film is hard to cut and is not easily processed. You can take advantage of advantages such as ease.

This heat-resistant layer comprises a binder resin, a slip agent, and
It is formed by suitably using a material to which a surfactant, inorganic particles, organic particles, a pigment, etc. are added. The binder resin used for the heat-resistant layer is, for example, a cellulose resin such as ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, nitrified cotton, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal. , Polyvinylpyrrolidone, acrylic resin, polyacrylamide, vinyl resin such as acrylonitrile-styrene copolymer, polyester resin, polyurethane resin, silicone-modified or fluorine-modified urethane resin, and the like.

Among these, those having several reactive groups, for example, those having a hydroxyl group, are used as a cross-linking agent.
It is preferable to use a crosslinked resin in combination with polyisocyanate or the like. The means for forming the heat-resistant layer is a coating liquid prepared by dissolving or dispersing a material obtained by adding a lubricant, a surfactant, inorganic particles, organic particles, a pigment, etc. to the binder resin as described above in a suitable solvent. Is prepared, and the coating solution is applied and dried by a conventional coating means such as a gravure coater, a roll coater, and a wire bar.

[0058]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. In the text, “part” or “%” is based on weight unless otherwise specified.

Example 1 As a substrate, one side of a 4.5 μm-thick polyethylene terephthalate film (Lumirror, manufactured by Toray Industries, Inc.) was coated with a coating solution for a colored layer having the following composition by gravure coating to obtain a dry coating amount. To 2.0 g / m ² and dried to form a colored layer. Furthermore, a coating liquid for a white hiding layer having the following composition was applied onto the colored layer by gravure coating so that the dry coating amount was 2.0 g / m ² , and the white hiding layer was formed by drying. The thermal transfer sheet of Example 1 is prepared. In addition, a heat-resistant layer coating solution having the following composition was previously applied to the other surface of the base material by gravure coating so that the dry coating amount was 0.1 g / m ² , and dried to form a heat-resistant layer. I had it.

Coating liquid for coloring layer: Blue pigment: Cyanine blue KRG (manufactured by Sanyo Dye Co., Ltd.) 9 parts Acrylic resin (BR113 manufactured by Mitsubishi Rayon Co., Ltd.) 21 parts Polyethylene wax 2 parts Toluene 34 parts Methyl ethyl ketone 34 parts White hiding layer coating liquid: Titanium oxide 40 parts (manufactured by Ishihara Sangyo Co., Ltd., CR-80, average particle size 0.25 μm) Vinyl chloride-vinyl acetate copolymer 5 parts (manufactured by Denki Kagaku Kogyo KK, Dencarac TF300K) Polyester resin (byron 200, Byron 200) 5 parts Toluene 20 parts Methyl ethyl ketone 20 parts Ethyl acetate 10 parts Heat-resistant layer coating liquid: Styrene acrylonitrile copolymer 11 parts Linear saturated polyester resin 0. 5 parts Zinc stearyl phosphate 5 parts Urea resin powder 5 parts Melamine resin powder 3 parts Toluene 4 0 part Methyl ethyl ketone 40 parts Example 2 In the thermal transfer sheet prepared in Example 1 above, the coating liquid for the coloring layer was changed to the following one, and the coating for the adhesive layer having the following composition was applied on the white hiding layer. The liquid was applied by gravure coating so that the dry coating amount was 0.6 g / m ² , and dried to form an adhesive layer, to prepare a thermal transfer sheet of Example 2.

Color layer coating liquid: Red pigment (Clariant Japan KK, Hostaperm E5B-02) 9 parts Acrylic resin (Mitsubishi Rayon KK, BR113) 21 parts Polyethylene wax 2 parts Toluene 34 parts Methyl ethyl ketone 34 parts Adhesive layer coating liquid: Acetal resin (Sekisui Chemical Co., Ltd., S-REC KS-1) 5 parts Carnauba wax 45 parts Isopropyl alcohol 25 parts Water 25 parts Example 3 Used as a substrate in Example 1. The same coating composition as described above was used, and one surface of the base material was gravure-coated with a coating solution having the same composition as the coating solution for the white hiding layer used in Example 1 to give a dry coating amount of 2. The white hiding layer was formed by coating and drying so that the coating amount was 0 g / m ² . Further, a coating solution having the same composition as the coating solution for the coloring layer used in Example 1 was applied onto the white hiding layer by gravure coating so that the dry coating amount was 2.0 g / m ^2. Then, the colored layer was formed by drying to prepare a thermal transfer sheet of Example 3.

Comparative Example 1 A thermal transfer sheet of Comparative Example 1 was prepared in the same manner as in Example 1 except that the white hiding layer was removed from the thermal transfer sheet prepared in Example 1 above.

Printing was performed under the following printing conditions using the thermal transfer sheets of the above-mentioned Examples and Comparative Examples, and the printed matter was subjected to the following method to obtain the C ^* L ^* a ^* b ^* color system. Color difference ΔE ^* ab and [(Δa ^* ) ² + (Δb ^* ) ² ].
The value of ^1/2 is measured and the visual readability is evaluated.

Printing conditions: As a printer to be used, CQL-4 manufactured by Astromed Co., Ltd.
In 2 and Comparative Example 1, two types of yellow label and silver label were used, and in Example 3, a transparent sheet was used and a character pattern was printed thereon.

Measurement conditions such as color difference: Coloring manufactured by Minolta Co., Ltd. was performed at two points, a recording portion (the portion having the thermal transfer ink layer) and a non-recording portion (the recording surface of the transferred material) of the print obtained above. A color difference meter CR-221 is used, a light source is D _65, and a color difference ΔE ^* ab of a CIE L ^* a ^* b ^* color system,
The value of [(Δa ^* ) ² + (Δb ^* ) ² ] ^1/2 was measured.

Further, regarding the printed matter using the thermal transfer sheets of Examples 1 and 2 and Comparative Example 1, the recording portion of the printed matter (the portion having the thermal transfer ink layer) and the coloring layer of the base material of the thermal transfer sheet used. The color difference with the ink layer measured from the surface not provided with was measured using the same color difference meter CR-221 manufactured by Minolta Co., Ltd. as described above. Regarding the printed matter using the thermal transfer sheet of Example 3, the printed surface side of the transparent sheet was provided with the recording portion of the printed matter when the silver label was overlaid and the colored layer of the base material of the used thermal transfer sheet. The color difference from the ink layer measured from the uncoated surface was measured. However, the heat transfer sheet was not coated with any layer such as a heat-resistant layer on the back side thereof.

The common light source D ₆₅ is JIS Z 87.
23 (1988) is a light source used for illumination,
It is a common light source whose relative spectral distribution is similar to the standard light D ₆₅ for color measurement. The standard light D ₆₅ to be approximated is light having a correlated color temperature of about 6504K and is used when displaying an object color illuminated by daylight.

The measurement results are shown in Tables 1 and 2 below.

[0069]

[Table 1]

[Table 2] Visual readability: The printed matter obtained under the above printing conditions is 5
The recorded information is visually observed from a distance of m and evaluated according to the following criteria.

⊚: The recorded information is very clear,
It was very easy to read the information.

B: The recorded information was clear and the information was easy to read.

Δ: The recorded information is slightly unclear,
Alternatively, the recording portion can be seen in a color different from the original color of the colored layer, and it is difficult to read the information a little.

X: The recorded information was very unclear, or the recording portion was visible in a color very different from the original color of the colored layer, and it was very difficult to read the information.

Table 3 below shows the results of evaluation of the visual readability of the above Examples and Comparative Examples.

[0075]

[Table 3]

[0076]

As described above, when the thermal transfer sheet is used in combination with the transfer target having a colored recording surface, the color difference between the ground color of the color recording surface and the color of the ink layer thermally transferred to the transfer target. Is CIE's L ^* a ^* b ^* color difference system, which is 55
Or more, or by defining the value of [(Δa ^* ) ² + (Δb ^* ) ² ] ^1/2 to be 40 or more, or the color of the ink layer thermally transferred to the transfer target and the thermal transfer. The difference between the color of the ink layer and the color of the ink layer measured from the other surface of the base material before the transfer is specified to be 10 or less, so that the transfer target is not affected by the color of the recording surface of the transfer target. The colored layer that is thermally transferred to the body can reproduce its original hue on the transferred body.

Further, the thermal transfer sheet is thermally transferred onto a transparent medium.
However, the printed surface of the heat-transferred transparent medium has a colored medium
When the bodies are stacked on top of each other, they are transferred by heat to a transparent medium.
The color of the formed ink layer was measured through the transparent medium,
The color difference between the letter side and the non-printed side is CIE L^*a^*b^*Color
Color difference formula of 55 or more, or [(Δa^*)^Two+ (Δb
^*)^Two]^1/2Stipulates that the value of is 40 or more
Of the ink layer thermally transferred to the transparent medium
Color measured through the transparent medium, transparent medium printing surface side
The color of the ink layer before overlaying the colored medium on
Color difference from the color of the ink layer after combining is 10 or less
By prescribing, the target area can be
The colored layer that is thermally transferred to the transfer body does not transfer its original hue.
It can be reproduced on the sketch.

[Brief description of drawings]

FIG. 1 shows an embodiment of the thermal transfer sheet of the present invention in which thermal transfer is performed on a transfer target having a colored recording surface.

FIG. 2 shows another embodiment of the thermal transfer sheet of the present invention in which thermal transfer is performed on a transfer target having a colored recording surface.

FIG. 3 shows another embodiment of the thermal transfer sheet of the present invention in which thermal transfer is performed on a transfer target having a colored recording surface.

FIG. 4 shows another embodiment of the thermal transfer sheet of the present invention in which thermal transfer is performed on a transfer target having a colored recording surface.

FIG. 5 shows an embodiment in which thermal transfer is performed on a transparent transfer target in the thermal transfer sheet of the present invention.

FIG. 6 shows another embodiment of the thermal transfer sheet of the present invention in which thermal transfer is performed on a transparent transfer target.

FIG. 7 shows another embodiment of the thermal transfer sheet of the present invention in which thermal transfer is performed on a transparent transfer target.

[Explanation of symbols]

1 base material 2 colored layers 3 White hiding layer 4 Adhesive layer 5 Release layer 6 Heat-resistant layer

Claims (15)

[Claims] 1. A thermal transfer sheet in which at least a coloring layer is provided on one surface of a substrate, wherein the thermal transfer sheet is used in combination with a transfer target having a colored recording surface. The color difference between the color of the ink layer thermally transferred to the body and the color of the ink layer measured from the surface opposite to the ink surface of the thermal transfer sheet before thermal transfer is L ^* a ^{* of the} International Commission on Illumination (CIE) ^. b ^{* A} thermal transfer sheet characterized in that it is 10 or less in a color difference type of color system. 2. A coloring layer is provided on at least one surface of a substrate.
A thermal transfer sheet having a color,
When used in combination with a transfer target with a recording surface
In addition, the color difference between the heat-transferred printed surface and the non-printed surface is
International Lighting Committee (CIE) L ^*a^*b^*Color difference formula of color system
Then, the thermal transfer sheet, which is 55 or more. 3. A coloring layer is provided on at least one surface of a base material.
A thermal transfer sheet having a color,
When used in combination with a transfer target with a recording surface
, The color of the printed surface and the non-printed surface that have been heat-transferred
International Lighting Committee (CIE) L ^*a^*b^*In color system
[(Δa^*)^Two+ (Δb^*)^Two]^1/2Value of 40 or more
A thermal transfer sheet characterized by being above. 4. A white hiding layer comprising a resin binder and at least one selected from titanium oxide, zinc oxide, silica, aluminum hydroxide, talc, clay and kaolinite on the colored layer. The thermal transfer sheet according to any one of 1 to 3. 5. The thermal transfer sheet according to claim 4, wherein an adhesive layer is provided on the white hiding layer. 6. A thermal transfer sheet in which at least a coloring layer is provided on one surface of a base material, wherein the thermal transfer sheet is thermally transferred to a transparent medium, and the printed surface of the thermally transferred transparent medium has a colored surface. When using the media of
When the color of the ink layer thermally transferred to the transparent medium is measured through the transparent medium, the color of the ink layer before superimposing the colored medium on the transparent medium printing surface side and the color of the ink layer after superimposing A thermal transfer sheet, characterized in that the color difference with the color is 10 or less in the L ^* a ^* b ^* color difference system of the International Commission on Illumination (CIE). 7. A thermal transfer sheet in which at least a coloring layer is provided on one surface of a substrate, wherein the thermal transfer sheet is thermally transferred to a transparent medium, and the printed surface of the thermally transferred transparent medium has a colored surface. When using the media of
The color difference between the printed surface and the non-printed surface obtained by measuring the color of the ink layer thermally transferred to the transparent medium through the transparent medium is the color difference formula of the International Commission on Illumination (CIE) L ^* a ^* b ^* color system. Then, the thermal transfer sheet, which is 55 or more. 8. A colored layer is provided on at least one surface of a base material.
A thermal transfer sheet, the thermal transfer sheet being a transparent medium.
Printed surface of the transparent medium that was heat-transferred to the body
In addition, when the medium with colored surface is used by overlapping,
The color of the ink layer thermally transferred to the transparent medium is changed to the transparent medium.
International illumination of printed and non-printed surfaces measured through the body
Ming Committee (CIE) L^*a^*b^*[(Δa
^*)^Two+ (Δb^*)^Two] ^1/2Is greater than or equal to 40
A thermal transfer sheet characterized by the above. 9. A white hiding layer comprising a resin binder and at least one selected from titanium oxide, zinc oxide, silica, aluminum hydroxide, talc, clay and kaolinite between the colored layer and the substrate. The thermal transfer sheet according to claim 6, wherein the thermal transfer sheet is provided. 10. The thermal transfer sheet according to claim 9, wherein an adhesive layer is provided on the colored layer. 11. The transfer medium and the colored medium have a surface made of at least one selected from organic pigments, inorganic pigments, metal flakes, glass flakes, glass beads, pearlescent pigments, and dyes. The thermal transfer sheet according to claim 1, which is a reflective sheet. 12. A printed matter obtained by forming a thermal transfer image on a retroreflective sheet using the thermal transfer sheet according to any one of claims 1 to 4. 13. A license plate comprising a transparent sheet and a printed sheet on the printed surface of the print according to claim 12. 14. A printed matter obtained by forming a thermal transfer image on a transparent transfer medium by using the thermal transfer sheet according to claim 5. 15. A license plate in which a retroreflective sheet is superposed on the printing surface side of the printed matter according to claim 14.