JP2007290343A - Thermal transfer sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer sheet, by which a printed material excellent in various durabilities such as light resistance or the like and being hard to develop catalytic fading can be formed. <P>SOLUTION: In the thermal transfer sheet, in which, as a dye layer including a binder resin, at least a yellow dye layer and a magenta dye layer are formed on a base material sheet, the yellow dye included in the yellow dye layer includes quinophthalon base compound and/or its tautomer and the magenta dye included in the magenta dye layer include two kinds of compound selected from the group consisting of an azo compound and an anthraquinone base compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a thermal transfer sheet in an image forming method using thermal transfer.

As a thermal transfer sheet in an image forming method using thermal transfer, a sublimation type thermal transfer sheet provided with a sublimation transfer type ink layer composed of a sublimation dye and a binder as a color material layer on one surface of a base film, or the sublimation There is known a heat melting type thermal transfer sheet provided with a heat melting transfer type ink layer made of pigment and wax in place of the transfer type ink layer.
The sublimation thermal transfer method generally performs full-color expression by sequentially superimposing three primary colors (three colors of yellow, magenta, and cyan. Black may be added as necessary) and sequentially printing gradations.

The image obtained by the heat-sensitive sublimation transfer method can form a high-quality image similar to a silver salt photograph, and accordingly, there is an extremely high demand for preventing image quality degradation due to factors such as light, heat, and humidity of the image. It's getting higher.
Conventionally, it has been proposed to select a suitable combination of dyes in order to improve image storage stability (see, for example, Patent Document 1), but the effect of improving the light resistance of intermediate colors is specifically shown. Not.

Phenomenon inferior in light resistance when combined with other dyes in the image layer even if the light resistance is sufficient when images are formed using a single dye for images obtained by the thermal sublimation transfer method (Catalytic photo-fading, so-called catalytic fading) can be a problem.
In contrast, when each color dye is thermally transferred from the thermal transfer sheet to two or more locations on the intermediate transfer medium and re-transferred to the transfer target, each color dye transferred to another location on the intermediate transfer medium is superimposed on the image. There has been proposed a thermal transfer recording method for forming (see, for example, Patent Document 2). However, this method is not an improvement of the thermal transfer sheet itself.
JP-A-8-11450 JP 2005-88515 A

The present invention has been made in view of the above-described situation, and an object of the present invention is to provide a thermal transfer sheet that is excellent in various fastnesses such as light resistance and capable of forming a printed matter that hardly causes catalytic fading.

The present invention provides a thermal transfer sheet in which at least a yellow dye layer and a magenta dye layer are formed on a base sheet as a dye layer containing a binder resin.
The yellow dye contained in the yellow dye layer is represented by the following general formula (1)

(In the formula, X represents a hydrogen atom or a halogen atom, and R represents an alkyl group having 1 to 5 carbon atoms, a hydrogen atom, an alkyl group and / or an acyl group having 6 to 10 carbon atoms in total having a benzene ring, or A magenta dye containing a quinophthalone compound and / or a tautomer thereof, which may have an ether oxygen and a C 2-10 alkoxycarbonyl group. Is the following general formula (2)

(Wherein R ¹ and R ² each independently represents an alkyl group having 2 or more carbon atoms, R ³ represents an alkyl group, and X represents a halogen atom), and Equations (3) and (4)

A thermal transfer sheet comprising at least two compounds selected from the group consisting of each anthraquinone compound represented by the formula:
The present invention is described in detail below.

First, it explains in full detail for every layer which comprises the thermal transfer sheet of this invention.
(Substrate sheet)
The substrate sheet in the present invention may be any sheet having a certain level of heat resistance and strength known in the art, such as polyethylene terephthalate film, 1,4-polycyclohexylenedimethylene terephthalate film, polyethylene naphthalate. Phthalate film, polyphenylene sulfide film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, cellulose derivatives such as cellulose acetate, polyethylene film, polyvinyl chloride film, nylon film, polyimide film, Resin films such as ionomer films; papers such as condenser paper, paraffin paper, and synthetic paper; non-woven fabrics; Body; and the like.
The substrate sheet generally has a thickness of about 0.5 to 50 μm, preferably about 3 to 10 μm.
The base sheet may be subjected to an adhesive treatment such as providing an adhesive layer (primer layer) on one or both sides as necessary.
Examples of the adhesion treatment include known surface modification methods such as corona discharge treatment, radiation treatment, roughening treatment, chemical treatment, plasma treatment, primer treatment, and grafting treatment.

(Dye layer)
The thermal transfer sheet of the present invention is one in which at least a yellow dye layer and a magenta dye layer are formed as a dye layer containing a binder resin.
In the thermal transfer sheet, a conventionally known cyan dye layer and black dye layer can be further formed as a dye layer.
The thermal transfer sheet may be one in which each dye layer is formed in the surface order. Examples thereof include those in which a plurality of dye layers such as yellow, magenta, cyan, and black are repeatedly provided in the surface order on the substrate sheet, and those in which the plurality of dye layers and the transferable protective layer are provided in the surface order. Black may be a hot-melt ink layer or a dye layer.

The yellow dye contained in the yellow dye layer is represented by the following general formula (1)

The quinophthalone compound represented by the formula (1) and / or a tautomer thereof (hereinafter, this dye may be referred to as “specific yellow dye”).
The specific yellow dye may contain only one kind of the quinophthalone compound represented by the general formula (1) and / or its tautomer in one dye layer, or two or more kinds thereof. It may be contained.

In the general formula (1), X represents a hydrogen atom or a halogen atom.
Examples of the halogen atom include F, Cl, Br, and I. Among them, Cl and Br are preferable.
In the general formula (1), R has an alkyl group having 1 to 5 carbon atoms, a hydrogen atom, an alkyl group and / or an acyl group having 6 to 10 carbon atoms having a benzene ring, or ether oxygen. Or an alkoxycarbonyl group having 2 to 10 carbon atoms.
The alkyl group and alkoxycarbonyl group as R may be either linear or branched.
Examples of the derivative of the alkyl group as R include an alkyl group in which a part of hydrogen atoms is substituted with nitrogen, the above-described halogen atom, or the like.
The acyl group as R is a concept including an aroyl group such as a benzoyl group. The aroyl group may be one in which 1 to 5 hydrogen atoms in the aromatic ring are independently substituted with an alkyl group having 1 to 3 carbon atoms, and the aromatic ring constituting the aroyl group is benzene. Examples thereof include a ring and a naphthalene ring, and a benzene ring is preferable.
R is preferably a hydrogen atom.

As said general formula (1), what is represented by a following formula is preferable.

Examples of the specific yellow dye include Disperse Yellow 54, Disperse Yellow 64, Disperse Yellow 149, and a quinophthalone dye described in JP-A-10-287818.
The quinophthalone compound represented by the general formula (1) and its tautomer can be generally synthesized in the same manner as a conventionally known quinophthalone compound.
When the specific yellow dye is contained in the specific yellow dye ink, the quinophthalone compound represented by the general formula (1) can form a tautomer thereof. The present invention also includes such tautomers.

The specific yellow dye preferably has an extinction coefficient in toluene of 10,000 to 150,000 ml / g · cm in terms of color developability.
In the present specification, the extinction coefficient is a value obtained by preparing a toluene solution containing 0.0002 wt% dye and measuring the extinction coefficient at the maximum absorption wavelength λmax with Shimadzu Corporation UV-3100PC.

The magenta dye contained in the magenta dye layer is represented by the following general formula (2)

(Wherein R ¹ and R ² each independently represents an alkyl group having 2 or more carbon atoms, R ³ represents an alkyl group, and X represents a halogen atom), and Equations (3) and (4)

And containing at least two compounds selected from the group consisting of each anthraquinone compound (hereinafter, the present dye may be collectively referred to as “specific magenta dye”).
In this specification, “containing at least two” means containing at least two compounds represented by different formulas, that is, any one of the above formulas (2), (3) and (4). Of the compounds represented by formula (2), the azo compound represented by formula (2) and the anthraquinone compound represented by formula (3), the anthraquinone compound represented by formula (3) and formula (4) The anthraquinone compound or the anthraquinone compound represented by the formula (4) and the azo compound represented by the formula (2).
The specific magenta dye is represented by the same formula in one dye layer as long as it contains at least two compounds represented by any one of the formulas (2), (3) and (4). Only one type of dye may be contained, or two or more types of dyes may be contained.
When the specific magenta dye contains each anthraquinone compound represented by the formula (3) and the formula (4), the light resistance can be improved, and among the azo compounds represented by the general formula (2) When it contains at least one and at least one of the anthraquinone compounds represented by formula (3) or formula (4), it is considered that light resistance and printing density can be improved.
The specific magenta dye preferably contains at least one of the azo compounds represented by the general formula (2) and at least one of the anthraquinone compounds represented by the formula (3) or the formula (4). Those containing the above three compounds are more preferred.

In the general formula (2), the R ¹ and Examples R ^2, preferably a linear or branched alkyl group having 2 to 8 carbon atoms each, a straight-chain or branched alkyl group having 3 to 5 carbon atoms, especially 3 carbon atoms A branched alkyl group of ˜5 is particularly preferred.
As said R < ³ >, a C1-C5 linear or branched alkyl group is preferable, and a C1-C3 linear or branched alkyl group is especially preferable.
Examples of the halogen atom for X include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. As said X, a chlorine atom or a bromine atom is preferable, and a chlorine atom is especially preferable.
In the azo compound represented by the general formula (2), R ¹ and R ² are alkyl groups having 2 to 8 carbon atoms, R ³ is an alkyl group having 1 to 5 carbon atoms, and X is a chlorine atom or A bromine atom is preferred.
As the azo compound, for example,

In particular, the compound represented by the following formula (I)

Is preferred.

The azo compound represented by the general formula (2) includes (i) the following general formula (II):

(In the formula, X is the same as defined above.)
And (ii) the obtained diazo solution is represented by the following general formula (III)

(Wherein R ¹ , R ² and R ³ are the same as defined above.)
(Iii) Further, an aqueous alkaline solution is added, and the precipitate is collected by filtration, washed with water and dried, and the following general formula (IV)

(Wherein R ¹ , R ² , R ³ and X are the same as defined above)
Can be obtained by a method of cyanating the bromine atom of the azo compound of the general formula (IV).
In the diazotization of (i) above, the aniline represented by the general formula (II) is dissolved in an acid solvent such as sulfuric acid or phosphoric acid, and then nitrosylsulfuric acid is added dropwise to perform diazotization to obtain a diazo liquid. . The amount of the acid solvent used is the same amount to 10 times the weight of the anilines, preferably the same amount to 5 times the weight, and the amount of the nitrosylsulfuric acid is represented by the general formula (II). It is 0.8-1.2 times mole with respect to the molar amount of anilines, Preferably it is 0.95-1.1 times mole.
In the diazotization of the anilines, the dropping temperature and the reaction temperature are generally −10 to 30 ° C., preferably −5 to 10 ° C., and the reaction time is generally 0.5 to 10 hours, preferably 1 to 5 hours. It is.

In the coupling reaction (ii), for example, the compound represented by the general formula (III) is dissolved or dissolved in an aqueous solvent containing sulfuric acid, phosphoric acid, hydrochloric acid, acetic acid, propionic acid, or a mixture of these acids. It is carried out by dispersing and mixing the diazo liquid.
The amount of the compound represented by the general formula (III) is generally 0.9 to 1.3 times mol, preferably 1.0 to 1. mol, relative to the molar amount of the anilines represented by the general formula (II). 2 moles.
In the coupling reaction, the dropping temperature and reaction temperature of the diazo liquid are generally −10 to 30 ° C., preferably −5 to 10 ° C., and the reaction time is 0.5 to 10 hours, preferably 1 to 5 hours. It is.

Examples of the alkaline aqueous solution used in the step (iii) include aqueous solutions of sodium acetate, potassium acetate, sodium hydroxide, potassium hydroxide, and the like.

The cyanation reaction (iv) is performed by reacting copper (I) cyanide in a polar solvent such as dimethylformamide or dimethyl sulfoxide.
The amount of copper (I) cyanide used is generally 2.0 to 2.5 times the molar amount of the azo compound represented by the general formula (IV).
In the above cyanation reaction, the reaction temperature is generally 50 to 150 ° C., preferably 70 to 90 ° C., and the reaction time is generally 1 to 5 hours.
Further, the cyanation reaction solution is discharged into water, and the precipitate is collected by filtration, washed with water, extracted with an organic solvent such as toluene, and then the extract is filtered to remove the metal component, and the organic layer is concentrated. The target azo compound represented by the above general formula (I) can be purified and recovered by dispersion treatment with aliphatic hydrocarbons such as n-heptane.

Examples of the compound represented by the above formula (3) include anthraquinone dyes such as Disperse Red 60, and examples of the compound represented by the above formula (4) include anthraquinone dyes such as Disperse Violet 26.

The specific magenta dye preferably has an extinction coefficient in toluene of 10,000 to 100,000 ml / g · cm in terms of color developability.
In the present specification, the extinction coefficient is a value measured in the same manner as the yellow dye.

Each of the dye layers contains a binder resin in addition to the specific dye.
The binder resin is not particularly limited, and conventionally known binder resins can be used. For example, cellulose resins such as methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose acetate, and cellulose butyrate; polyvinyl Examples thereof include vinyl resins such as alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, and polyacrylamide; polyester resins; phenoxy resins;

Examples of the binder resin further include a releasable graft copolymer. The releasable graft copolymer can be blended as a release agent.
The releasable graft copolymer comprises at least one releasable segment selected from a polysiloxane segment, a fluorocarbon segment, a fluorinated hydrocarbon segment, and a long-chain alkyl segment. It is obtained by graft polymerization on the chain.
Among these, the releasable graft copolymer is preferably a graft copolymer obtained by grafting a polysiloxane segment to a main chain composed of polyvinyl acetal.

The dye layer may use additives such as a release agent, inorganic fine particles, and organic fine particles as desired.
Examples of the release agent include the above-described releasable graft copolymer, silicone oil, and phosphate ester.
Examples of the inorganic fine particles include carbon black, aluminum, and molybdenum disulfide.
Examples of the organic fine particles include polyethylene wax.

Each of the above-described dye layers is formed from a dye ink containing a specific dye, a binder resin, an additive to be added as required, and a solvent.
The solvent is not particularly limited as long as it is a conventionally known dye ink material. For example, acetone, methanol, water, methyl ethyl ketone, toluene, ethanol, isopropyl alcohol, cyclohexanone, dimethylformamide [DMF], ethyl acetate, A mixed solvent of these solvents can be used, and among them, a mixed solvent of methyl ethyl ketone and toluene is preferable.

In the dye ink containing the specific yellow dye (hereinafter sometimes abbreviated as “specific yellow dye ink”), the specific yellow dye is generally 50 to 300 parts by mass, preferably 100 parts by mass with respect to 100 parts by mass of the binder resin. 150 to 250 parts by mass.
In general, the dye ink is one in which the yellow dye is dispersed in the binder resin and a solvent. The yellow dye content is a mass%, and the solubility of the yellow dye in the solvent is s mass% at 20 ° C. And satisfy the relationship represented by the formula a> s.

In the specific yellow dye ink, the dye can be present in an amount more than twice the limit of dissolving in the solvent, and in an amount far exceeding the limit of dissolving in the solvent solution of the binder resin. It is also possible to do.
In this specification, “dispersion” means that the dye ink is not allowed to be visually confirmed after standing for 168 hours (7 days) at a temperature of 20 to 25 ° C. With respect to the specific yellow dye, the limit of dissolving in a solvent means the mass of the dye when the dye is dissolved to the maximum in a solvent of 100 ° C. at a temperature of 20 ° C., and is dissolved in the solvent solution of the binder resin. The limit means the mass of the dye when the dye is maximally dissolved at a temperature of 20 ° C. in 100 g of a solvent in which 1% by weight of the binder resin is dissolved.

In the thermal transfer sheet of the present invention, the specific yellow dye ink used for forming the yellow dye layer is such that the solvent dissolves the binder resin, and the particle size distribution of the yellow dye has a D50 particle size of 0.1 to 5. It is preferable that 0 micrometer and D90 particle size are 0.3-10.0 micrometer.
If the D50 particle size is less than 0.1 μm, it may cause background stains of the resulting dye layer, and if it exceeds 5.0 μm, the resulting dye layer may have insufficient transfer sensitivity. The D50 particle size has a more preferable lower limit of 0.3 μm and a more preferable upper limit of 3.0 μm.
If the D90 particle size is less than 0.3 μm, the background stains and the like may occur. If the D90 particle size exceeds 10.0 μm, the background stains (colored without heating with a thermal head) due to the resulting dye layer. May occur.

In the present specification, the D50 particle size is a particle size at which the cumulative particle size is 50%, and is an index of the average particle size, and the D90 particle size is a particle at which the cumulative particle size is 90%. It is a value representing the diameter and serving as an index for understanding the existence state of coarse particles.
The above D50 particle size and D90 particle size were measured using a Nikkiso Co., Ltd. Microtrac particle size distribution analyzer UPA-150, solid content concentration 8.75% by mass (of which dye concentration 5.25% by mass, binder resin concentration 3 .5 mass%) is a value calculated from the particle size distribution measured under each measurement condition.
(Measurement condition)
Measurement principle: Dynamic light scattering method Light source: Semiconductor laser Wavelength: 780 nm
Sample cell: SUS316

Conventionally, the quinophthalone compound represented by the above general formula (1) and / or a tautomer thereof has not been practically used as a dye ink because of its low solubility in a solvent. On the other hand, the specific dye ink in the present invention can be contained as a dye at a practical level as a material for the dye layer in the thermal transfer sheet even if the specific yellow dye has low solvent solubility. Therefore, it is possible to provide a dye layer of a thermal transfer sheet that can form an excellent quality printed product.

The specific yellow dye ink generally has a specific yellow dye content a of 1% by mass or more, and may be about 20% by mass or less as long as it is within the above range.
The content a of the specific yellow dye has a preferable lower limit of 1% by mass and a preferable upper limit of 15% by mass.
In the specific yellow dye ink, the total amount of the dye such as the specific yellow dye and the binder resin, that is, the solid content is preferably about 2 to 30% by mass, more preferably 5 to 15% by mass. preferable.
In the present specification, when the specific yellow dye ink contains two or more dye compounds, the content a and the solid content of the specific yellow dye both represent a range related to the total of the respective dye compounds.

In the dye ink containing the specific magenta dye (hereinafter sometimes abbreviated as “specific magenta dye ink”), the total amount of the specific magenta dye is generally 50 to 300 parts by mass with respect to 100 parts by mass of the binder resin. Preferably, 150 to 250 parts by mass is appropriate.
In the specific magenta dye ink, the total amount of the specific magenta dye and the binder resin, that is, the solid content is preferably about 2 to 30% by mass, and more preferably 15 to 20% by mass.

The above dye inks are, for example, paint shakers, propeller type stirrers, dissolvers, homomixers, ball mills, bead mills, sand mills, two roll mills, three roll mills, ultrasonic dispersers, kneaders, line mixers, twin screw extruders, etc. It can prepare using a conventionally well-known manufacturing method.
The specific yellow dye ink is preferably prepared using a disperser such as a bead mill or a ball mill in that the specific yellow dye is uniformly dispersed.
Examples of the beads and balls in the bead mill or ball mill include glass, ceramic, steel, and zirconia.
The bead diameter of the bead mill or ball mill may be selected according to the initial particle diameter of the specific yellow dye, but is generally preferably 0.05 to 2.0 mm.

Each said dye layer can be formed by apply | coating each said dye ink by conventionally well-known methods, such as the reverse roll coating method using a wire bar coating, a gravure printing method, and a gravure plate, for example.
As the coating method, gravure coating is preferred.
Although it does not specifically limit in the said coating, It is preferable to dry for about 1 second-about 5 minutes at the temperature of 60-120 degreeC.
If the above-mentioned dye ink is insufficiently dried, the dye ink will turn over when it is soiled or rolled up, and when the turned-off dye ink is turned over, it will retransfer to the dye layer that has a different hue. So-called kickback may occur.
The dye ink may be applied so that the dry coating amount is preferably about 0.2 to 3.0 g / m ² , more preferably about 0.4 to 1.0 g / m ² .

Since the thermal transfer sheet of the present invention has a yellow dye layer containing the above-mentioned specific yellow dye and a magenta dye layer containing the above-mentioned specific magenta dye as the dye layer, printing is performed by combining the dye layers. However, it is possible to obtain a printed matter having excellent light resistance and little catalytic fading.

(Other layers)
1. Heat-resistant slip layer The thermal transfer sheet of the present invention may further be provided with a heat-resistant slip layer on the substrate sheet surface opposite to the surface on which the dye layer is formed.
The heat resistant slipping layer is provided to prevent problems caused by heat of the thermal head during thermal transfer, such as sticking and printing wrinkles.

The heat-resistant slip layer is mainly composed of a heat-resistant resin.
The heat-resistant resin is not particularly limited. For example, polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer resin, polyether resin, polybutadiene resin, styrene-butadiene copolymer resin. , Acrylic polyol, polyurethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, urethane or epoxy prepolymer, nitrocellulose resin, cellulose nitrate resin, cellulose acetate propionate resin, cellulose acetate butyrate resin, cellulose acetate-hydro Diene phthalate resin, cellulose acetate resin, aromatic polyamide resin, polyimide resin, polyamideimide resin, polycarbonate resin, Fluorinated polyolefin resins.

The heat-resistant slip layer may be formed by blending additives such as a slipperiness-imparting agent, a crosslinking agent, a release agent, an organic powder, and an inorganic powder in addition to the heat-resistant resin.

In general, the heat-resistant slipping layer is coated with the heat-resistant slipping layer by adding the above-mentioned heat-resistant resin, and optionally adding the slipperiness-imparting agent and additives to the solvent and dissolving or dispersing each component. After preparing the liquid, the heat resistant slipping layer coating liquid can be applied on a substrate and dried.
As the solvent in the heat resistant slipping layer coating solution, the same solvent as that in the dye ink can be used.
Examples of the coating method of the heat resistant slipping layer coating solution include wire bar coating, gravure printing, screen printing, reverse roll coating using a gravure plate, and gravure coating is particularly preferable.
The heat-resistant slip layer coating solution, dry coating amount is preferably 0.1 to 3 g / ^{m 2,} more preferably may be applied so as to be 1.5 g / ^{m 2} or less.

2. As long as the thermal transfer sheet of the present invention has the above-described dye layer on the base sheet, an undercoat layer or the like is provided between the base sheet and the dye layer. Also good.
In the present invention, the undercoat layer is not particularly limited, and a composition that improves the adhesion between the substrate and the dye layer can be appropriately selected and provided.
The thermal transfer sheet of the present invention may be one in which a release layer is provided on the surface of the dye layer opposite to the base material sheet.
The release layer is preferably made of a resin having excellent release properties, such as the above-described release graft copolymer.

The thermal transfer sheet of the present invention may be one in which a transfer protective layer is further formed in the surface order with the above-mentioned dye layer so that a protective layer for protecting the image surface can be transferred after image formation.
The configuration and preparation of the protective transfer layer are not particularly limited, and can be selected from conventionally known techniques depending on the characteristics of the substrate sheet, dye layer, and the like to be used.
When the base film is not releasable, the transfer protective layer is preferably provided with a release layer between the base film and the transfer protective layer to improve the transfer property of the transfer protective layer.

The thermal transfer sheet of the present invention heats and pressurizes a predetermined portion with a thermal head or the like on the side opposite to the dye layer of the base film, and transfers the dye corresponding to the printing portion of the dye layer to the transfer material. Can be printed.
A thermal transfer image receiving sheet or the like can be used as the transfer material.
The thermal transfer image-receiving sheet is not particularly limited as long as the recording surface has dye acceptability. For example, a dye-receiving layer is formed on at least one surface of a substrate such as paper, metal, glass, or synthetic resin. Things can be mentioned.
The printer used for performing the thermal transfer is not particularly limited, and a known thermal transfer printer can be used.

Since the thermal transfer sheet of the present invention has the above-described configuration, it is possible to obtain a printed material that is excellent in various fastnesses such as light resistance, moisture resistance, and heat resistance and has little catalytic fading.

Next, an Example and a comparative example are given and this invention is explained in full detail. In the text, “part” or “%” is based on mass unless otherwise specified.

Example 1
(Preparation of yellow dye ink)
1. About 250 parts of the following amount of dye, binder resin and solvent, and an average particle size of 0.3 mm zirconia beads are added to a 200 ml cup size glass bottle, and the dye is added for 3 hours with a paint shaker (manufactured by Asada Tekko Co., Ltd.) A yellow dye ink was prepared by dispersing.
<Yellow dye ink composition>
Dye Y-1 5.25 parts polyvinyl acetal resin (ESREC KS-5, manufactured by Sekisui Chemical Co., Ltd.) 3.5 parts methyl ethyl ketone 45.635 parts toluene 45.635 parts

The chemical formula of Dye Y-1 is as follows.

(Preparation of magenta and cyan dye inks)
2. The mixture was completely dissolved by operating an ultrasonic disperser for 20 minutes, and mixed by using magenta dye ink and cyan dye ink.
<Magenta dye ink composition>
Dye M-1 2.08 parts Dye M-2 1.84 parts Dye M-3 2.72 parts Polyvinyl acetal resin (ESREC KS-5, manufactured by Sekisui Chemical Co., Ltd.) 3.5 parts Methyl ethyl ketone 45 parts Toluene 45 parts

The chemical formulas of Dye M-1 to Dye M-3 are as follows.

<Cyan dye ink composition>
Dye C-1 3.0 parts Dye C-2 3.5 parts Polyvinyl acetal resin (ESREC KS-5, manufactured by Sekisui Chemical Co., Ltd.) 3.5 parts Methyl ethyl ketone 45 parts Toluene 45 parts

The chemical formulas of Dye C-1 to Dye C-2 are as follows.

(Creation of thermal transfer sheet)
As a base sheet, the above dye inks were applied on a polyethylene terephthalate [PET] film having a thickness of 4.5 μm by gravure coating so that the dry coating amount was 0.6 g / m ² . Each dye layer was formed by drying for 2 minutes to produce the thermal transfer sheet of Example 1.
In addition, a heat resistant slipping layer coating solution having the following composition was applied to the other surface of the base sheet by gravure coating in advance so that the dry coating amount was 1.0 g / m ² and dried. A sex layer was formed.

<Heat resistant slip layer coating solution composition>
Polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 13.6 parts polyisocyanate curing agent (Takenate D218, manufactured by Takeda Pharmaceutical Co., Ltd.) 0.6 parts Phosphate ester (Plysurf A208S, Daiichi Kogyo Seiyaku Co., Ltd.) 0.8 parts Methyl ethyl ketone 42.5 parts Toluene 42.5 parts

Example 2
A thermal transfer sheet of Example 2 was produced in the same manner as in Example 1 except that the yellow dye was changed to the dye Y-2 represented by the following formula.

Example 3
In the yellow dye ink, the thermal transfer sheet of Example 3 is the same as Example 1 except that the yellow dye is changed to the dye Y-1 (4.2 parts) and the dye Y-2 (1.05 parts). Was made.

Example 4
A thermal transfer sheet of Example 4 was produced in the same manner as in Example 1 except that the yellow dye was changed to the dye Y-3 represented by the following formula.

Example 5
In the yellow dye ink, the yellow dye is changed to the dye Y-1 (4.2 parts) and the dye Y-2 (1.05 parts), and in the magenta dye ink, the magenta dye is changed to the dye M-1 (2. 08 part) and the dye M-2 (1.84 parts), except that the thermal transfer sheet of Example 5 was produced in the same manner as in Example 1.

Example 6
In the yellow dye ink, the yellow dye is changed to the dye Y-1 (4.2 parts) and the dye Y-2 (1.05 parts), and in the magenta dye ink, the magenta dye is changed to the dye M-1 (2. 08 part) and the dye M-3 (2.72 part), except that the thermal transfer sheet of Example 6 was produced in the same manner as in Example 1.

Example 7
In the yellow dye ink, the yellow dye is changed to the dye Y-1 (4.2 parts) and the dye Y-2 (1.05 parts), and in the magenta dye ink, the magenta dye is changed to the dye M-2 (1. 84 parts) and the dye M-3 (2.72 parts), except that the thermal transfer sheet of Example 7 was produced in the same manner as in Example 1.

Comparative Example 1
A thermal transfer sheet of Comparative Example 1 was prepared in the same manner as in Example 1 except that the magenta dye ink was changed to the dye M-1 (5.25 parts).

Comparative Example 2
In the same manner as in Example 1 except that the yellow dye is changed to the above dye Y-2 in the yellow dye ink, and the magenta dye is changed to the dye M-1 (5.25 parts) in the magenta dye ink. The thermal transfer sheet of Example 2 was produced.

Comparative Example 3
In the yellow dye ink, the yellow dye is changed to the dye Y-1 (4.2 parts) and the dye Y-2 (1.05 parts), and in the magenta dye ink, the magenta dye is changed to the dye M-1 (5. Except for changing to 25 parts), a thermal transfer sheet of Comparative Example 3 was produced in the same manner as in Example 1.

Comparative Example 4
Example 1 except that in the yellow dye ink, the yellow dye is changed to the dye Y-4 represented by the following formula, and in the magenta dye ink, the magenta dye is changed to the dye M-1 (5.25 parts). Similarly, a thermal transfer sheet of Comparative Example 4 was produced.

Table 2 shows the solubility and particle size distribution of the yellow dye used in each Example and each Comparative Example.

In the table, the dye solubility is determined by adding each dye at 3 w / v% to toluene / MEK = 1/1 (mass ratio), heating and stirring at 50 ° C., and allowing to stand at 25 ° C. for 60 hours. The presence or absence of dye precipitation was determined visually, and the yellow dye solubility was 2 hours at 40 ° C. after preparing 20 g of a yellow solution with 5% by mass of methyl ethyl ketone / toluene = 1/1 at a temperature of 20 ° C. After stirring for 72 hours, 5 g of the upper part of the solution was collected and filtered with a filter paper having a diameter of 185 mm (manufactured by Toyo Filter Paper Co., Ltd.). The solubility was calculated from the amount of the remaining dye, and the particle size distribution measurement was calculated from the particle size distribution in the ink measured using Nikkiso Co., Ltd. Microtrac particle size distribution analyzer UPA-150. In addition, the yellow dye ink which implemented dye solubility, yellow dye solubility, and a particle size distribution measurement is a thing of Examples 1-4 and the comparative example 4. FIG.

Each Example and Comparative Example was evaluated by the method shown below.

<Light resistance>
1. Preparation of printed matter A4 size standard paper dedicated to P-400 printer manufactured by OLYMPUS was used as the transfer target. The dye layer of each thermal transfer sheet and the dye receiving surface of the above-mentioned transfer material are opposed to each other, and the yellow dye layer, the magenta dye layer, and cyan are used from the back side of the thermal transfer sheet using a test printer (manufactured by Wedge) under the following conditions. Printing is performed in the order of the dye layer, and the gradation pattern 18step of 0/255 to 255/255 (density Max) is black (3Bk), yellow (Y), magenta (M), cyan (C), blue (B), Green (G) and red (R) print patterns were formed, and colorimetry was performed for each gradation.
(Printing conditions)
・ Thermal head: F3598 (Toshiba Hokuto Electronics Co., Ltd.)
-Heating element average resistance: 5176 (Ω)
・ Print density in the main scanning direction: 300 dpi
-Sub-scanning direction printing density: 300 dpi
・ Printing power: 0.12 (W / dot)
1 line cycle: 2 (msec.)
・ Pulse duty: 85%
-Printing start temperature: 35.5 (° C)

2. Measurement of Hue Change Full-color images obtained by the above application are obtained with a xenon weatherweometer (Atlas, Ci4000: illuminance 120,000 lux, black panel temperature 45 ° C., filter CIRA, soda lime, internal environment 30 ° C., 20%). irradiation is performed for 96 hours, color change before and after irradiation (ΔE * ab = ((after irradiation L * - before irradiation L ^*) 2 + (after irradiation a * - before irradiation a ^*) 2 + (after irradiation b * - irradiated Previous ^{b *) 2) 1/2;.} ( wherein, L represents a lightness, a, b represents the perceived lightness index also, L *, a *, b * is, CIE1976L * a * b * color specification In addition, the residual concentration ratio (%) of red at that time (concentration after irradiation / concentration before irradiation) was also measured.
(Colorimetric conditions)
Colorimeter: Spectrometer SpectroLino (manufactured by Gretag Macbeth)
・ Light source: D65
-Filter: ANSI Status A
-Viewing angle: 2 °
3. Measurement of yellow and magenta concentrations Measurement was performed using a spectrophotometer SpectroLino manufactured by Gretag Macbeth (colorimetric conditions, density: ANSI Status A, hue: light source D65, viewing angle 2 °).

The measurement results are shown in Table 2. ΔE * ab represents the highest value among the steps of each color, and among the remaining density ratio (%) of red at that time, “RY” represents the remaining density ratio of yellow at the time of measuring the red hue change. “R−M” represents the residual density ratio of magenta when the red hue change is measured.

From the above results, the prints obtained from Examples 1 to 7 can form yellow and magenta prints having excellent light resistance, and the red also has a high concentration residual ratio, and catalytic fading. It turned out that it is hard to occur. On the other hand, the printed matter obtained from each of the comparative examples using only one type of magenta dye has a large hue change and a low residual density rate particularly with respect to red, so that it is found that catalytic fading is likely to occur. It was. As the magenta dye, the thermal transfer sheets of Examples 1 to 6 having the dye layer in which the dye M-1 and the above-described anthraquinone compound coexist not only have good light resistance but also have a maximum magenta density of 2.0 or more. It was confirmed that a print of

Since the thermal transfer sheet of the present invention has the above-described configuration, it is possible to obtain a printed material that is excellent in various fastnesses such as light resistance and has little catalytic fading.

Claims (4)

On the base sheet, in a thermal transfer sheet in which at least a yellow dye layer and a magenta dye layer are formed as a dye layer containing a binder resin,
The yellow dye contained in the yellow dye layer is represented by the following general formula (1)

(In the formula, X represents a hydrogen atom or a halogen atom, and R represents an alkyl group having 1 to 5 carbon atoms, a hydrogen atom, an alkyl group and / or an acyl group having 6 to 10 carbon atoms in total having a benzene ring, or Represents an alkoxycarbonyl group having 2 to 10 carbon atoms which may have ether oxygen.), And / or a tautomer thereof.
The magenta dye contained in the magenta dye layer has the following general formula (2)

(Wherein R ¹ and R ² each independently represents an alkyl group having 2 or more carbon atoms, R ³ represents an alkyl group, and X represents a halogen atom), and Equations (3) and (4)

A thermal transfer sheet comprising at least two compounds selected from the group consisting of each anthraquinone compound represented by the formula: The thermal transfer sheet according to claim 1, wherein the magenta dye includes at least one of the azo compounds and at least one of the anthraquinone compounds. The azo compound has the following formula (I)

The thermal transfer sheet according to claim 1, wherein the thermal transfer sheet is a compound represented by the formula: The yellow dye layer is formed from a dye ink containing a yellow dye composed of the quinophthalone compound represented by the general formula (1) and / or a tautomer thereof, a binder resin, and a solvent,
In the dye ink, by dispersing the yellow dye in the binder resin and the solvent, the yellow dye content a mass% in the yellow dye ink and the solubility of the yellow dye in the solvent at 20 ° C. The thermal transfer sheet according to any one of claims 1 to 3, wherein s mass% satisfies a relationship represented by the formula a> s.