JPH0497895A - Thermal transfer material and image forming method - Google Patents

Abstract

PURPOSE:To provide a thermal transfer material improved in the thermal diffusibility, chelating properties and hue of a dye while holding the light fastness, heat resistance and fixing properties of an image and obtaining a black image by one kind of a dye by providing a layer containing a specific dye on a support. CONSTITUTION:A thermal transfer material is formed by providing a layer containing a dye represented by general formula [I] (wherein X is an atom group forming a nitrogen-containing heterocyclic ring, G is a chelatable group and R<1>, R<2>, R<3> and R<4> are an alkyl group) on a support. The thermal layer of this thermal transfer material is superposed on an image receiving material and heat is applied to the thermal transfer material corresponding to image data and an image is formed on the image receiving material by the chelate dye formed by a metal ion and the dye in the thermal layer. The above- mentioned dye can absorb of light within the almost entire region of a visible part and, therefore, a black image excellent in gradation and having good light fastness is formed and, since the dye forms a chelate in an image receiving layer, the image having good fixing properties is formed.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a thermal transfer material and an image forming method, and more particularly, to a novel thermal transfer material that provides a black image with excellent spectral characteristics, heat resistance, and fixing properties. The present invention relates to a material and an image forming method that enables efficient recording using the material.

[Prior Art and Problems to be Solved by the Invention] Conventionally, recording techniques such as an ink sheet method, an electrophotographic method, and a thermal transfer method have been considered as a method of obtaining a hard copy.

Among these, the thermal transfer method has advantages such as easy operation and maintenance, miniaturization of the device and low cost, and low running cost.

In this thermal transfer method, a transfer sheet (thermal transfer material) having a meltable ink layer (thermal layer) on a support is heated by a thermal head, and the ink is melted and transferred onto the transfer sheet (image receiving material). Thermal diffusion transfer method (sublimation) heats a transfer sheet with an ink layer containing a heat-diffusible dye (sublimable dye) on a support using a thermal head, and transfers the heat-diffusible dye to the transfer sheet. There are two types of transfer methods (transfer methods), but the latter thermal diffusion transfer method changes the amount of dye transferred in response to changes in the thermal energy of the thermal head, making it possible to control the gradation of the image. So,
This is advantageous in terms of recording gradation images.

However, in thermal transfer recording using the thermal diffusion transfer method,
The dye used in thermal transfer materials is important, and conventional dyes have the disadvantage that the stability of the resulting images, that is, the light resistance and fixing properties are poor.

In order to improve this point, JP-A-59-78893,
Publications No. 59-109394 and No. 60-2398 disclose an image forming method in which a chelatable heat-diffusible dye is used to form an image with the chelated dye on an image-receiving material. .

These methods are excellent methods for improving light fastness and fixing properties, but on the other hand, they are not always satisfactory in terms of dye diffusion, chelation properties, and hue, and further improvements are desired. was.

Furthermore, the dyes used in these methods have the disadvantage that they require mixing three color dyes, yellow, magenta, and cyan, to form a black image, making the production process complicated.

The present invention has been made to improve the above situation.

That is, the object of the present invention is to maintain the light fastness, heat resistance, and fixing properties of images while improving the thermal diffusivity, chelation properties, and color tone of dyes, and to provide a feeling that black images can be obtained using a kind of dye. An object of the present invention is to provide a thermal transfer material and an image forming method.

[Means for solving the above problem] The present invention according to claim 1 for achieving the above object,
This is a heat-sensitive transfer material characterized by comprising a layer containing at least a dye represented by the following general formula [I] on a support.

Further, the present invention according to claim 2 provides a heat-sensitive recording material in which a layer containing a dye represented by the general formula [I] according to claim 1 is provided on a support, and an image-receiving material is superimposed on the layer. , an image forming method characterized in that the heat-sensitive recording material is heated in accordance with image information, and an image is formed on the image-receiving material using a chelate dye formed by a reaction between the dye and metal ions.

However, in the general formula [I], X is an atomic group necessary to form a nitrogen-containing heterocycle, G represents a chelatable group, and R1, R2, R3R4 are the same or different from each other. Represents an alkyl group that may have a substituent.

The dye represented by general formula [I] will be explained in more detail.

The nitrogen-containing heterocycle formed including X is preferably a 5- to 6-membered nitrogen-containing heterocycle (the heterocycle may further form a condensed ring with another ring). Representation,
Particularly preferred is a pyridine ring.

G represents a chelatable group, preferably an -OH group.

R1, R2, R3 and R4 each represent an alkyl group which may have a substituent, preferably an alkyl group having 1 to 6 carbon atoms, and particularly preferably a methyl group or an ethyl group.

Further, R', R2 and R3, R' are bonded to each other to form a ring (
For example, a morpholine ring) may be formed.

Examples of substituents for R1-R4 include aryl groups (e.g., phenyl groups, etc.), alkoxy groups (e.g., methoxy groups, ethoxy groups, etc.), amino groups (e.g., methylamino groups,
ethylamino group, etc.), acylamino group (e.g. acetyl group, etc.), sulfonyl group (e.g. methanesulfonyl group, etc.)
, an alkoxycarbonyl group (for example, a methoxycarbonyl group), a cyano group, a nitro group, a halogen atom (for example, a chlorine atom, a fluorine atom, etc.).

Typical specific examples of the dyes used in the present invention are shown below.

BK-8.

The dye used in the present invention can be synthesized in accordance with, for example, the synthesis method disclosed in JP-A-58-17437.

The heat-sensitive transfer material of the present invention comprises a layer containing a dye represented by the general formula [I] (hereinafter sometimes referred to as a heat-sensitive layer) on a support.

The content of dye in the heat-sensitive layer is 0 per support.
．． 05g to 10g is preferred.

The heat-sensitive layer is formed by dissolving one or more of the dyes together with a binder in a solvent, or by dispersing them in the form of fine particles in a solvent, or by preparing a paint for forming a heat-sensitive layer by a hot-melt method. onto the support,
It can be formed by drying appropriately.

The thickness of the heat-sensitive layer is preferably 0.1 Bm to suLm in dry film thickness.

The binder includes water-soluble polymers such as cellulose, polyacrylic acid, polyvinyl alcohol, and polyvinylpyrrolidone, acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, polyether sulfone, polyvinyl butyral, polyvinyl acetal, and nitrocellulose. , ethylcellulose, etc.

These binders can be used not only by dissolving one or more of them in an organic solvent, but also by dispersing them in a latex form.

The amount of binder used is 0.0 per m' of support.
5 to 30 g is preferred.

The solvents include water, alcohols (eg ethanol, propatool), cellosolves (eg ethyl acetate), aromatics (eg toluene).

xylene, chlorobenzene), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, dioxane), chlorinated solvents (eg, chloroform, trichloroethylene), and the like.

The support may be one that has good dimensional stability and can withstand the heat of the thermal head during recording, or it may be a thin paper such as condenser paper or glassine paper, or a heat-resistant material such as polyethylene terephthalate boriamate or polycarbonate. A plastic film is preferably used.

The thickness of the support is preferably 2 to 30 μm, and the support may have a subbing layer for the purpose of improving adhesion with the binder and preventing transfer and dyeing of the dye to the support. good.

Furthermore, an anti-sticking layer may be provided on the back surface of the support (the side opposite to the heat-sensitive layer) for the purpose of preventing the head from sticking to the support.

The heat-sensitive transfer material of the present invention is provided on the heat-sensitive layer by JP-A-59-10
It may have a heat-fusible layer containing a heat-fusible compound as described in Japanese Patent No. 6997.

As this heat-melting compound, colorless or white compounds having a melting point of 65 to 130°C are preferably used, such as waxes such as carnauba wax, beeswax, and campli wax, higher fatty acids such as stearic acid and behenic acid, Examples include alcohols such as xylitol, amides such as acetamide and benzamide, and ureas such as phenylurea and diethylurea.

Note that these heat-melting layers may contain a polymer such as polyvinylpyrrolidone, polyvinyl butyral, or saturated polyester, in order to improve the retention of the dye.

According to the heat-sensitive transfer material of the present invention, it is possible to obtain a black image with gradation using a kind of dye as described below, or when it is applied to full-color image recording, a cyan heat-sensitive layer containing a cyan dye, A total of four layers, a magenta heat-sensitive layer containing a magenta dye, a yellow heat-sensitive layer containing a yellow dye, and a heat-sensitive layer containing the dye according to the present invention, are repeatedly coated in sequence on the same surface of the support. That's preferable.

In the image forming method of the present invention, the heat-sensitive layer of the heat-sensitive transfer material and the image-receiving material are overlapped, heat corresponding to image information is applied to the heat-sensitive transfer material, and the image is formed by the reaction between metal ions and the dye in the heat-sensitive layer. An image is formed on the image-receiving material by the chelating dye.

The metal ions may be present in the image-receiving material or in a heat-fusible layer provided on the surface of the heat-sensitive layer.

To explain the above-mentioned image forming method with reference to the drawings, in FIG. The dye in the heat-sensitive layer 5 of the heat-sensitive transfer material 6 is
For example, the dye is diffused into the image-receiving material 3 by heat from the heating resistor 8 of the thermal head 7, and reacts with the metal ions in the image-receiving layer 2 to form a chelate dye.

Further, in FIG. 2, when the metal ions are present in the heat-fusible layer 9 provided on the surface of the heat-sensitive layer 5, the support 4
A heat-sensitive transfer material IO consisting of a heat-sensitive layer 5 and a heat-fusible layer 9
For example, the dye in the heat-sensitive layer 5 of the thermal head 7
The dye is diffused into the heat-fusible layer 9 by the heat from the heating resistor 8, and reacts there with the metal ion to form a chelate dye.

Part or all of the heat-fusible layer 9 containing this chelate dye 9a is removed from the image receiving material 3 by cohesive failure or interfacial peeling.
to move to.

Examples of the metal ions include divalent and polyvalent metals belonging to Groups 1 to 2 of the periodic table;
, Co, Cr, Cu, Fe, Mg, Mn,
Mo.

Ni, Sn, Ti and ln are preferred, especially Ni
, Cu, Cr, Co and Zn are preferred.

Compounds that supply these metal ions (hereinafter sometimes referred to as metal sources) include inorganic or organic salts of the metals and complexes of the metals, and among them, organic acid salts and complexes. preferable.

To give a specific example, N12i'' Cu 2 +, Cr
Examples include salts of lower fatty acids such as o 2 + and ln 2+ with acetic acid, salts of higher fatty acids such as stearic acid, and salts of aromatic carboxylic acids such as benzoic acid and salicylic acid.

Further, complexes represented by the following general formula can also be preferably used.

[M(Q,)1(Q2) −(Q3)−] ”(Y −
) - tatashi, in the above formula, M is a metal ion, preferably N
120, Cu2+, Cr, CO2+, ln2+.

Q,,Q2. Q represents a coordination compound capable of forming a coordination bond with the metal ion represented by M, and may be the same or different.

These coordination compounds include, for example, chelate chemistry (
5) (Nankodo).

Y represents an organic anion, and specific examples thereof include tetraphenylboron anion and alkylbenzenesulfonate anion.

The symbol represents an integer of 1.2 or 3, m represents 1.2 or O, n represents 1 or O, or these represent whether the complex represented by the above general formula is tetradentate or hexadentate. Q2. It is determined by the number of ligands of Q.

p represents 1 or 2, preferably 2.

When p is 2, the coordination group of the coordination compound represented by Q, Qa, Q, is not anionized.

The amount of the metal source added is usually preferably 0.5 to 20 g/m2, more preferably 1 to 20 g/m2, based on the image receiving material or the heat-melting layer.

Note that the image-receiving material used in the present invention generally has a support of paper, a plastic film, or a paper-plastic film composite, and an image-receiving layer formed on the support by polyester resin, polyvinyl chloride resin, dolphin chloride, or other suitable materials. It is formed by forming a layer of one or more types of polymers such as a copolymer resin with a polymer (for example, vinyl acetate, etc.), polyvinyl butyral, polyvinylpyrrolidone, polycarbonate, etc.

Further, the support itself may be used as an image-receiving material.

[Example] Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited thereto (Example 1) One coating material was mixed with the following raw materials to obtain a uniform solution coating material containing the heat-diffusible pigment according to the present invention.

Heat-diffusible dye BK-1...10g Nitrocellulose resin...20g Methyl ethyl ketone...400ml l-Thermal transfer material- Apply the above paint to a thickness of 4. A heat-sensitive transfer material was prepared by applying and drying the coating onto a 5 pm polyethylene terephthalate film using a wire bar so that the coating amount after drying was 1.0 g/cm.

Note that a nitrocellulose layer containing a silicone-modified urethane resin (SP-2105, manufactured by Dainichiseika Chemical Co., Ltd.) is provided on the back surface of the polyethylene terephthalate film as a sticking prevention layer.

1. Preparation of image-receiving material - Polyethylene was laminated on both sides of paper, and one side of the polyethylene layer [contains a white pigment (Ti02), a bluing agent, and the following metal source (applied amount: 5 g/m2). ] As an image-receiving layer, a vinyl chloride resin containing 0.15 g 7 m 2 of silicone oil was applied in an amount of 10 g/m'' to obtain an image-receiving material.

The structure of this image-receiving material is explained with a drawing as shown in FIG. 3, in which polyethylene layers 12a,
12b is laminated with polyethylene layer 1 on one side.
A polyvinyl chloride resin layer 13 is laminated on 2a.

1. Image forming method 1. Layer the heat-sensitive transfer material and image-receiving material so that the paint-coated surface of the heat-sensitive transfer material and the image-receiving surface of the image-receiving material face each other, and apply a heat-sensitive head to the back surface of the heat-sensitive transfer material under the following recording conditions. Image recording was performed.

Table 1 shows the hues (on, 1o, on, 72, half width) of the obtained dye images.

Linear density of main scanning and sub-scanning: 28 dots/us Recording crab
Heating time of 0.6 W/dot thermal head: The heating time was adjusted stepwise between 20 m5 ec and 0.2 m5 ec.

Image stability (light resistance): The light resistance was evaluated by irradiating the sample with light for 96 hours using a xenon phase meter.

Metal source: [N1(C2H5NHCH2CIIJt(2)]”[(
CJ(s)Jl 2- (Examples 2 to 5) In Example 1, dye BK-1 was replaced with BK-2, BK-3.
Four types of heat-sensitive transfer materials were prepared in the same manner as in Example 1 except that , BK-6, and BK-7 were used, and images were formed using them.

The hues of the dye images are as shown in Table 1.

(Comparative Example 1) A heat-sensitive transfer material was prepared in the same manner as in Example 1 except that a comparative dye (A) having the following structural formula was used instead of dye BK-1, and Image formation was performed using

The hues of the dye images are as shown in Table 1.

As shown in the upper table of Table 1, the dye according to the present invention has two absorption peaks near 500 nm and 600 nm, and has a large half-width, so it absorbs light in almost the entire visible range. Therefore, a black image with excellent mW properties was formed.

Furthermore, since the dye according to the present invention had good light resistance and formed a chelate in the image-receiving layer, the image fixability was also good.

On the other hand, the comparative dye also has two absorption peaks, but the difference between the two peaks is as small as 30 nm, and the half-width is also small.
Although a good magenta image can be obtained, it has not been possible to form a black image when used alone.

[Effects of the Invention] According to the present invention, there is provided a heat-sensitive recording material which maintains image fastness, heat resistance, and fixing properties, and which has improved dye chelation properties, color tone, and heat diffusivity, and which can be used to improve efficiency. It is possible to provide an image forming method that allows good recording.

According to the heat-sensitive recording material and image forming method of the present invention, a black image with excellent gradation can be obtained using one type of dye without using multiple types of dyes such as yellow, magenta, and cyan.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams of an image forming method using the heat-sensitive transfer material of the present invention. FIG. 3 is a sectional view showing an example of an image receiving material. l...Support, 2...Image receiving layer, 3...Image receiving material,
4...Support, 5...Thermosensitive layer. 6...Thermal transfer material, 7...Thermal head, 8.
...Heating resistor, 9...Thermofusible layer. 10... Thermal transfer material, 11... Paper, 12a, 12
b... Polyethylene layer, 13... Vinyl chloride resin layer.

Claims (2)

[Claims] (1) A heat-sensitive transfer material comprising a layer containing a dye represented by the following general formula [I] provided on a support. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] (In the formula, X represents an atomic group necessary to form a nitrogen-containing heterocycle, G represents a chelatable group,
R^1, R^2, R^3, and R^4 represent an alkyl group which may have the same or different substituents. ) (2) An image-receiving material is superimposed on the layer of a heat-sensitive recording material comprising a layer containing a dye represented by the general formula [I] according to claim 1 provided on a support, and the heat-sensitive recording material is converted into image information. 1. An image forming method comprising forming an image on an image-receiving material using a chelate dye formed by a reaction between the dye and a metal ion.