JPH0383685A - Method for forming thermal transfer image - Google Patents

Abstract

PURPOSE:To form a thermal transfer image improved in gradation and fixing properties by heating a thermal transfer material formed by providing a thermal layer containing a dye having a phenolic hydroxyl group to the surface of a support from the rear of the support corresponding to image data. CONSTITUTION:A thermal transfer material is formed by laminating a thermal layer containing a dye having at least a phenolic hydroxyl group to a support. This thermal transfer material is heated from the rear of the support corresponding to image data to form the color image corresponding to the aforementioned image data on an image receiving material in the presence of a basic compound and/or a mordant. As a pref. embodiment of the dye having the phenolic hydroxyl group to be used, an azo dye, an anthraquinone dye, an azomethine dye or the like each of which has the phenolic hydroxyl group are designated and the use amount thereof is pref. about 0.1 - 20g per one m<2> of the support.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermal transfer material, and more specifically to a thermal transfer image forming method capable of obtaining a color image with good gradation and good fixability. Regarding.

[Background of the Invention] In recent years, color recording techniques such as inkjet, electrophotography, and thermal transfer have been studied as methods for obtaining color hard copies.

Among these, the thermal transfer method in particular has excellent advantages such as ease of operation and maintenance, miniaturization and cost reduction of the device, and low running costs.

In this thermal transfer method, a thermal transfer recording material (also referred to as a transfer sheet) having a meltable ink layer on a support is heated by a thermal head, and the ink is transferred onto an image receiving material (also referred to as a transfer sheet). A heat-sensitive transfer recording material having an ink layer containing a heat-diffusible dye (sublimable dye) on a support is heated by a thermal head to transfer the heat-diffusible dye to an image-receiving material. There are two types of thermal diffusion transfer methods (sublimation transfer methods), but the latter method changes the gradation of the image by changing the amount of dye transferred according to changes in the thermal energy of the thermal head. Since it can be controlled, it is advantageous for full-color recording.

However, in this thermal diffusion transfer method, the dye used is simply dissolved in the polymer used for the image-receiving layer of the image-receiving material, and the retention of the dye is weak, resulting in poor fixing properties. Furthermore, the image density and sharpness deteriorate over time due to dye re-diffusion. If it is left for a long time with a polyvinyl chloride sheet (added polyvinyl chloride sheet, etc.), the dye may be re-transferred to the polymer sheet and the image may deteriorate, or organic solvents (e.g. ethanol, acetone, etc.) may dissolve or diffuse the image quality dye. There are drawbacks due to poor fixing properties such as deterioration of image quality.

On the other hand, by combining certain dyes and mordants,
It is known that the fixing properties of dye transferred images are improved in image forming methods using diffusion transfer type photographic materials.
These dyes have -5O, Nl2 groups as mordant groups,
-5O3H groups, -COOH groups, etc., and dyes with these groups do not diffuse even when used in thermal transfer systems.Therefore, no attempt has been made to fix dyes using mordants in thermal transfer systems. Therefore, these improvements were strongly desired.

Also, JP-A-59-64393, JP-A No. 59-224844
No. 61-162042, No. 61-237694, No. 62-7594, No. 62-23790, No. 62
-152897 and other publications propose selecting an image-receiving material and/or performing post-processing after transfer in order to improve image fixation, but none of these methods are sufficient. However, it needs to be improved.

Therefore, based on the above-mentioned viewpoint, the present inventor continued various studies on dyes for thermal transfer and found that dyes having phenolic hydroxyl groups not only have good transferability but also excellent mordanting properties. , on the basis of which the present invention was completed.

[Object of the Invention] Therefore, an object of the present invention is to improve the above-mentioned drawbacks, and to provide a color thermal transfer image with good gradation, good diffusivity, and good fixing properties. An object of the present invention is to provide a thermal transfer image forming method that can obtain the following.

[Structure of the Invention] An object of the present invention is to heat a heat-sensitive transfer material having a heat-sensitive layer containing a dye having at least a phenolic hydroxyl group on a support according to image information from the back side of the support, This was achieved by a thermal transfer image forming method characterized by forming a dye image according to the image information in the presence of a basic compound and/or a mordant.

The present invention will be explained in more detail below.

The dye having a phenolic hydroxyl group used in the present invention is a hydroxyl group substituted on an aromatic ring, and in particular, the pK of Tsumego.
A dye having a hydroxyl group in which a is 12 or less is preferable.
As the aromatic ring, a benzene ring is particularly preferred, and this benzene ring may be fused with another ring to form a fused ring such as a naphthalene ring or anthraquinone ring.

The dye is not particularly limited as long as it has a phenolic hydroxyl group, but azo dyes, anthraquinone dyes, and azomethine dyes that have a phenolic hydroxyl group are preferable, and specifically, the basics of photographic engineering, silver salts, etc. Photography edition (edited by the Photographic Society of Japan), page 205~'! Dyes obtained by oxidative coupling of active methylene type (open chain methylene type, closed methylene type) and phenolic couplers and p-aminophenol derivatives described on page J212 are preferred.

Examples are given here, but the present invention is not limited to these.

The following margins are Dye-A Dye-B Dye-C υn υ■ Dye-D Dye-E The dye used in the present invention can be used to form a dye image in the presence of a basic compound (or alkaline agent) and/or mordant. Specifically, the dye is fixed by forming a salt with a basic compound, or by being adsorbed to a mordant, or by forming a dye image in the presence of a basic compound and a mordant. It means to be formed and established. Among these, particularly preferred is one that is adsorbed to a mordant and fixed to form a dye image.

In the present invention, the basic compound and/or mordant are added to the image-receiving material (usually referred to as the image-receiving layer), but when the heat-sensitive transfer material has a two-layer structure as described later, they are added to the heat-fusible layer. may be done. A basic compound may also be added to the ink layer. In those cases, the image-receiving layer does not necessarily need to contain a basic compound and/or a mordant.

The basic compound used in the present invention is not particularly limited, but inorganic or organic basic compounds are used, such as calcium carbonate, sodium carbonate, sodium acetate,
Examples include alkyluayon and aryluayon.

In the present invention, it is preferable to use a mordant, and it is particularly preferable to add a mordant to the image-receiving layer.

The mordant used in the present invention includes a compound having a tertiary amino group, a compound having a nitrogen-containing heterocyclic group, and a compound having a quaternary cation group thereof.

When a mordant is used in the image-receiving layer, it is preferable that the mordant is immobilized, and a polymer mordant is particularly preferred. When the mordant is added to the heat-melting layer of the thermal transfer material, a mordant with a molecular weight of 400 or less is preferable. preferable.

Specific representative examples of the mordant used in the present invention are listed below in the margins, but the present invention is not limited to these examples.

(Numbers represent mol%) -1 -2 -3 -4 The nitrogen-containing heterocyclic group is preferably an imidazole group or a pyridyl group, and specific examples of the polymer mordant having a grid include the following polymers.

-5 + CHxCH+ro -6- 7- -9 -10 -1 1 P-12 P-13 -14 -15 Specific examples of the polymer mordant having a quaternary ammonium group include the following polymers.

-16 L CH3-N"-CH3 Cl- -17 Clh N" CHi 2- -18 Shi=tts -19 -20 -21 Js P-22 P-23 1- Used in the thermal transfer image forming method of the present invention Thermal transfer materials are produced by preparing an ink containing the dye by dissolving the dye together with a binder in a solvent or dispersing it in the form of fine particles, and applying the ink onto a support and drying it to form an ink layer or heat-sensitive transfer material. You get layers.

The amount of the dye used in the present invention is preferably 0.1 g to 20 g per 1 m 2 of the support.

The heat-sensitive transfer material thus obtained is produced by preparing an image-receiving material, aligning the heat-sensitive layer and the image-receiving layer surface, and then applying heat from the back side of the support of the heat-sensitive transfer material according to the image information according to the method of the present invention. When given, the dye corresponding to this thermal image is diffused into the image-receiving layer, where the dye is fixed and a dye image is obtained.

The binder includes water-soluble polymers such as cellulose, polyacrylic acid, polyvinyl alcohol, and polyvinylpyrrolidone; organic solvents such as acrylic resin, methacrylic resin, polystyrene, polycarbonate, polysulfone, polyethersulfone, and ethyl cellulose;
There are soluble polymers. When using a polymer soluble in an organic solvent, it may be used not only by being dissolved in the organic solvent, but also in the form of a latex dispersion.

The amount of binder used is 0.1 per m2 of support.
g to 50 g is preferred.

The support used in the present invention may be any material as long as it has good dimensional stability and can withstand the heat during recording with a thermal head, including thin paper such as condenser paper, glassine paper, polyethylene terephthalate, polyamide, etc. A heat resistant plastic film such as polycarbonate can be 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, a slipping layer may be provided on the back surface of the support (the side opposite to the ink layer) for the purpose of preventing the head from adhering to the support.

The ink layer, ie, the heat-sensitive layer, used in the present invention is coated on a support or printed on the support by a printing method such as a gravure method. The thickness of the heat sensitive layer is 0.1μ in dry film thickness.
m to 5 μm is preferable.

Solvents for preparing the ink for the heat-sensitive layer include water, alcohols (e.g. ethanol, propatool), cellosolves (e.g. ethyl acetate), aromatics (e.g. toluene, xylene, chlorobenzene), ketones (e.g. acetone). , methyl ethyl ketone), ethers (eg, tetrahydrofuran, dioxane), chlorinated solvents (eg, chloroform, trichlorethylene), and the like.

The heat-sensitive transfer material used in the present invention basically consists of an ink layer, that is, a heat-sensitive layer, consisting of the dye and binder used in the present invention on a support. It may have a heat-fusible layer containing a heat-fusible compound as described in Japanese Patent No. 59-106997.

Furthermore, when the thermal transfer material used in the present invention is applied to full-color image recording, a cyan ink layer containing a cyan dye, a magenta ink layer containing a heat-diffusible magenta dye, and a heat-diffusible yellow dye are provided on the support. It is preferable that three layers of yellow ink layers containing yellow ink layers are sequentially and repeatedly applied.

Further, in addition to the yellow, magenta, and cyan layers, an ink layer containing a black image-forming substance may be further coated as needed, so that a total of four layers are repeatedly coated in sequence.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited only to these examples.

Example 1 [Ink layer (heat-sensitive layer)] A mixture having the following composition was treated with a paint conditioner to obtain a uniform solution ink containing a heat-diffusible pigment used in the present invention.

Pigment compound Dye-A 10 g Polyvinyl butyral resin 15 g Methyl ethyl ketone 150 txfl Toluene 150 rn (1 [Preparation of transfer sheet] The ink containing the above heat diffusible dye was coated in a thickness of 15 μm.
A layer containing a heat-diffusible dye is formed by coating on a support made of a polyester film using a wire bar so that the coating weight after drying is 1.0 g/m''e, and drying. A thermal transfer material-1 was produced.

Similarly, instead of Dye-A of thermal transfer material-1,
Dye-B to Dye-E and Dye-F described below
Thermal Transfer Materials-2 to 8 were prepared in the same manner as Thermal Transfer Material-1 except that dyes of %Dye-G and Dye-H were used.

[Preparation of image-receiving material] 100 g of latex dispersion containing 10% polymer mordant (P-16)! ,=10 g of polyvinylpyrrolidone was dissolved and coated on photographic baryta paper so that the amount of polyvinylpyrrolidone (binder) was 10g per 1++'' of support to prepare image-receiving material-A.

Similarly, Table-1 Image-receiving material-B having the composition shown in ~G was produced.

Dye-F Dy@-G Dye-H CFJ Thermal Transfer Image Forming Method] The heat-sensitive transfer sheet and image-receiving material obtained as described above are placed so that the ink-coated surface of the heat-sensitive transfer sheet and the image-receiving surface of the image-receiving material face each other. The thermal transfer sheets were placed one on top of the other, and a thermal head was applied from the back side of the thermal transfer sheet to record an image. As a result, an image with excellent gradation was obtained.

Table 2 shows the maximum density of the obtained image.

The recording conditions at this time are as follows.

Linear density of main scanning and sub-scanning: 4 dots/ll11 Recording power: 0.8 W/dot Heating time of thermal head: 20 m5ec (applied energy: approx. 11.2 x 1 G
-'J) to 2 m5ec C applied energy approximately 1.1
The heating time was adjusted stepwise between 2 x 10-'J).

As is clear from Table 2, high density thermal transfer images can be obtained by using the method of the present invention.

Example 2 The image-receiving layer side of the images obtained in Example 1 (No. 1 to No. 14) was laminated with high-quality paper for dry electrophotography, and dioctyl phthalate (30%) was added as a plasticizer. After applying a pressure of 30 g/c- from above and leaving it at a temperature of 60°C for 3 days, the high-quality paper was peeled off from the image-receiving material, and the high-quality paper was separated from the image-receiving material. The density of each retransferred image was measured.

The results obtained are shown in Table 3.

As is clear from Table 3, images with excellent fixability can be obtained by the method of the present invention.

Example 3 The same thermal transfer recording as in Example 1 was performed using the thermal transfer material and image-receiving materials A to G produced in Example 1. Table 4 shows the density and hue of the obtained image. Furthermore, fixability (non-retransferability) was obtained for those images in the same manner as in Example 2.
A test was conducted. The results are also shown in Table 4.

As is clear from Table 4, images with high density, good hue, and excellent fixing properties can be obtained by the method of the present invention. The effects of the present invention are particularly remarkable for those using mordants other than dyes.

[Effects of the Invention] The thermal transfer image forming method of the present invention has good II tonality,
Furthermore, color images with excellent fixability can be obtained.

Claims (1)

[Claims] A heat-sensitive transfer material having a heat-sensitive layer containing a dye having at least a phenolic hydroxyl group on a support is heated from the back side of the support according to image information, and the presence of a basic compound and/or mordant is detected on the image-receiving material. A method for forming a thermal transfer image, which comprises forming a dye image according to the image information.