JP2918232B2 - Sublimation type thermal transfer media - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sublimation type thermal transfer medium, particularly to a sublimation type thermal transfer medium for multiple printing.

2. Description of the Related Art In recent years, the demand for full-color printers has been increasing year by year, and recording methods of this full-color printer include an electrophotographic method, an ink-jet method, and a thermal transfer method. Among them, thermal transfer is easy due to easy maintenance and no noise. Many methods are used.

This thermal transfer consists of a solidified color ink sheet and an image receiving paper, and heat transfer or sublimation transfer of the ink to the receiving paper by thermal energy controlled by an electric signal of a laser, a thermal head, etc., to form an image. This is a recording method to be performed.

The thermal transfer recording system is roughly classified into the heat melting transfer type and the sublimation transfer type. In particular, in the latter case, the sublimation dye sublimates in a monomolecular state corresponding to heat energy from a thermal head or the like in principle. It has the advantage that halftones can be easily obtained and the gradation can be controlled arbitrarily, and is considered to be the most suitable method for a full-color printer.

However, in this sublimation transfer recording method, a color ink sheet is used as a recording supply, and a heating process is selectively performed according to an image signal. In order to obtain one full-color image, yellow, magenta, cyan, (black) (1) Ink sheet is used one by one, and even if there is an unused portion, it is discarded.

Therefore, focusing on this drawback, the ink sheet and the image receiving body are moved at a constant speed in order to improve the drawback by using the ink sheet a number of times, and the constant speed mode method used repeatedly and the running speed of the ink sheet are used. There has been proposed an N-fold mode method in which the first use portion and the second use portion of the color material layer are used while being slightly shifted from each other at a later time than that of the image receiving body.

However, in the sublimation type thermal transfer recording system, sublimation and evaporation reactions are basically zero-order reactions, and in the constant velocity mode, although the amount of dye that can withstand multi-use is included in the ink layer, As the number of prints increases, the transfer density particularly in the high image density area rapidly decreases,
There was a drawback that printing could not be carried out many times.

The reason that the thick conventional ink layer uniformly containing a sufficient amount of dye capable of withstanding printing many times causes a sharp decrease in density after the second printing is that (i) the dye contributing to transfer is very small on the free surface of the ink layer. It was found that the reason was that the dye was very near the free surface of the ink layer every time printing was performed, because the dye was transferred only near the vicinity and (ii) the transfer of the dye obeyed Fick's law.

Based on this finding, the present inventors have applied a dye from the dye supply layer to the lower layer of the dye transfer contributing layer in order to replenish the dye consumed in the upper layer (free surface layer) of the dye transfer contributing layer by printing. It has been proposed to design each layer so that the dye releasing ability is in the relationship of dye supply layer> dye transfer contributing layer so that it can be easily compensated (see Japanese Patent Application No. 63-62866). However, according to this method, when the dye is contained in an excessively dispersed state, the surface of the ink sheet loses smoothness, an image is disturbed such as missing dots, or the image has no gloss,
In some cases, high energy is required to obtain a sufficient image density.

The present invention overcomes the drawbacks of the prior art, prevents deterioration of image quality by keeping the surface of the dye transfer-contributing layer smooth, and can print multiple times with sufficient gloss and sufficient image density. It is an object of the present invention to provide a mold thermal transfer medium.

Structure The present inventors have conducted intensive studies to achieve the above object, and as a result, on a substrate, a dye supply layer and a dye transfer contributing layer each containing a sublimable dye in an organic binder sequentially from the substrate side. In a sublimation type thermal transfer medium obtained by laminating
The dye supply layer and the dye transfer contributing layer are formed as a single layer on the substrate with the same amount of adhesion in each of the respective formulations, each of which is overlapped with a separate image receiving layer, and the same thermal energy is applied to both. Then, the amount of dye transferred to each image receiving layer is in the relationship of dye supply layer> dye transfer contributing layer, and the content of the dye contained in the dye transfer contributing layer is the amount of the dye with respect to the organic binder. Saturation solubility
It has been found that the object can be achieved by providing a sublimation type thermal transfer medium characterized in that the sublimation type thermal transfer medium is contained at a ratio of 95 to 100 when the ratio is set to 100.

A preferred embodiment of the present invention is a sublimation-type thermal transfer medium, wherein the content of the dye contained in the dye transfer-contributing layer is contained by the saturation solubility of the dye in an organic binder.

Here, the “saturated solubility” refers to a state in which the dye is dissolved in the binder resin in the maximum amount (a state in which the dye is not dissolved even if it is further dissolved). When the content of the dye is equal to or higher than the saturation solubility, the dye is precipitated. In the present invention, the dye content of the dye transfer-contributing layer is contained in the maximum amount in which the dye is soluble in the binder, so that a high-density image is obtained and the surface of the dye-transfer contributing layer is smoothened (because there is no undissolved dye ), The purpose of the present invention is to prevent the image from missing dots and decrease in glossiness.

The present invention is an invention disclosed in Japanese Patent Application No. 63-62866 of the present applicant, that is, a dye supply layer in which a sublimable dye is dispersed in an organic binder in order from the substrate side, and In a sublimation type thermal transfer medium obtained by laminating a dye transfer contributing layer, the dye supply layer and the dye transfer contributing layer are formed as a single layer on the substrate with the same adhesion amount in each of the formulations, and each of them is separately formed. A sublimation type thermal transfer medium, wherein the amount of dye transferred to each image receiving layer is in the relationship of dye supply layer> dye transfer contributing layer when the same thermal energy is applied to both the image receiving layers. It is an improvement of the invention relating to the present invention.

The present invention relates to a thermal transfer medium configured as described above,
It is characterized in that the content of the dye contained in the dye transfer contributing layer is near the saturation solubility with respect to the binder forming the transfer contributing layer. More specifically, the content of the dye contained in the dye transfer contributing layer is characterized by being contained in a ratio of 95 to 100 when the saturated solubility of the dye in the organic binder is 100. .

The content of the dye contained in the dye transfer contributing layer is 100 when the saturated solubility of the dye in the organic binder is 100.
When the amount is larger, the amount of the dye to be deposited increases, the smoothness of the surface of the dye transfer contributing layer cannot be maintained, and the image quality becomes poor, such as missing dots of an image and a decrease in glossiness. If it is less than 95, it is not possible to maintain a sufficient dye density necessary for recording many times, resulting in a decrease in image density.

With such a configuration, the recorded image density can be maximized, and printing can be performed many times with stable image density. Further, since the surface of the dye transfer contributing layer has high smoothness, the image is not disturbed such as missing dots, and a glossy recorded image can be obtained.

Known dyes, sublimable dyes, binders and the like used in the dye transfer contributing layer and the dye supply layer forming the ink layer of the present invention can be used.

Examples of the binder resin used for forming such a dye transfer contributing layer include, for example, polyvinyl butyral, polyvinyl acetate, polyvinyl chloride, polyester, cellulose resin, phenol resin, acrylic resin, polystyrene, polycarbonate, Epoxy resins and the like can be mentioned.

Further, the sublimable dye used together with such a binder may be any one used mainly in thermal transfer printing such as disperse dyes, oil-soluble dyes, and for example, CI Disperse Yellow 1,3,8,9. , 16,41,54,60,77,116 etc., CI Disperse Red 1,4,6,11,15,55,59,60,73,83 etc., CI Disperse Blue 3,14,19,26, 56, 60, 64, 72, 99, 108 etc., C.
I. Solvent Yellow 77,116 etc., CI Solvent Red 23, 25, 27 etc., and CI Solvent Blue 36,83,10 etc.
5 and the like. These dyes can be used singly, but can be used by mixing several kinds.

Further, the content of the dye contained in the dye supply layer is not particularly limited, but is desirably a saturation solubility or higher in the binder since recording is performed many times.

The binder and the dye used in such a dye supply layer are as follows:
The same binders and dyes used for the dye transfer contributing layer described above can be used.

When a dye concentration gradient is provided between the dye transfer contributing layer and the dye supply layer, the dye concentration of the dye contributing layer may be 1.1.
５5 times, preferably 1.5 to 3 times.

The thickness of the dye transfer contributing layer forming such an ink layer is generally 0.05 to 5 μm, preferably 0.1 to 2 μm.
m, and the thickness of the dye supply layer is generally 0.1 to 20.
μm, preferably 0.5 to 5 μm.

As the base sheet, a film such as a condenser paper, a polyester film, a polystyrene film, a porsulfone film, a polyimide film, or a polyamide film is used. If necessary, a conventional adhesive layer is used between the base sheet and the dye supply layer. May be provided,
If necessary, a conventional heat-resistant lubricating layer may be provided on the back surface of the base sheet.

Although the above description has been made with reference to a recording method using a thermal head, the transfer medium of the present invention is a recording method in which recording heat energy is applied by a method other than the thermal head, for example, a thermal printing plate, a laser beam, or a support. It can also be used for a method using Joule heat generated in a medium such as a body. Of these, the so-called energetic thermal transfer method using Joule heat generated in a medium is best known, for example, USP
4,103,066, JP-A-57-14060, JP-A-57-11080, or JP-A-59-9906.

When used in this energization transfer method, relatively heat-resistant polyester, polycarbonate, triacetyl cellulose, nylon, polyimide, aromatic polyamide and other resins as a support, aluminum, copper, iron, tin, zinc,
Metal powders such as nickel, molybdenum, silver and / or conductive powders such as carbon black are dispersed to adjust the resistance to an intermediate value between insulators and good conductors. A support on which metal is deposited or sputtered may be used. The thickness of these supports is preferably about 2 to 15 microns in consideration of the efficiency of Joule heat conduction.

In the case of using a laser beam transfer method, a material that absorbs laser light and generates heat may be selected as a support.
For example, a conventional heat transfer film containing a light-absorbing heat exchange material such as carbon, or a film having an absorption layer formed on the front and back surfaces of a support is used.

Hereinafter, the present invention will be described more specifically based on the following examples, but the present invention is not limited thereto.

Example 1 [Saturation solubility of dye in binder] Cyan dye, Kayaset Blue 714 (Nippon Kayaku Co., Ltd.)
The saturation solubility of the binder in polyvinyl butyral BX-1 (manufactured by Sekisui Chemical Co., Ltd.) was determined as follows.

15 g of a 5% polyvinyl butyral BX-1 solution (toluene / methyl ethyl ketone = 1/1 weight ratio) and 0.6 g of Kayaset Blue 714 (the amount of the dye was polyvinyl butyral BX
(80% by weight based on the weight of -1) in a ball mill for 24 hours, and then this solution was applied to a slide glass with a wire bar and air-dried. The coated slide glass was transparent, and there was no precipitation of dye. Subsequently, repeating the same test while sequentially increasing the amount of the dye to the binder, the amount of the dye was 95% by weight based on the amount of the binder (when the weight of the binder was 0.75 g, the amount of the dye was Up to 0.71g)
The coated slide glass was transparent and no precipitation of dye was observed. However, at 96% by weight (0.72 g), the coated slide glass became cloudy and became opaque, and dye precipitation was observed in some places. Was done. Therefore, the saturation solubility of Kayaset Blue 714 in polyvinyl butyral BX-1 was 95% by weight.

Preparation of sublimation type thermal transfer media [Composition of supply layer] Parts by weight Polyvinyl butyral resin BX-110 (manufactured by Sekisui Chemical Co., Ltd.) Sublimation dye Kayaset Blue 714 13.5 (manufactured by Nippon Kayaku Co., Ltd.) Solvent Toluene 100 Methyl ethyl ketone 100 [Dye transfer contributing layer composition] parts by weight Polyvinyl butyral resin BX-110 (manufactured by Sekisui Chemical Co., Ltd.) Sublimation dye Kayaset Blue 714 9.5 (manufactured by Nippon Kayaku Co., Ltd.) Solvent Toluene 100 methyl ethyl ketone 100 After dispersing the composition of the above formulation in a ball mill for 24 hours, the ink composition for dye supply layer was formed to a thickness of 2.4 μm on a 8.5 μm polyimide film (manufactured by Toray DuPont) using a wire bar. After the application, the ink composition for a dye transfer contributing layer having the above formulation was further applied thereon so as to have a thickness of 0.8 μm to form a sublimation type thermal transfer medium.

This sublimation type thermal transfer medium is applied to receiving paper (Supply VY-S100 for Hitachi Video Printer VY-50) by a thermal head under the printing conditions of an applied density of 6 dots / mm, an applied power of 455 mW / dot, and a maximum applied energy of 2.50 mJ / dot. Printing was performed a number of times at the same location, the image densities were compared, and gloss and dot omission of the image were observed. The result is
It is shown in the table.

Examples 2 to 5 and Comparative Examples 1 to 5 The saturation solubility of the dye in various binders was determined in the same manner as in Example 1, and sublimation type thermal transfer media were prepared with the compositions shown in Table 1.

[Dye supply layer composition] parts by weight Binder: polyvinyl butyral resin BX-110 Dye: (see Table 1 for types and amounts used) Solvent: toluene 100 methyl ethyl ketone 100 [dye transfer contributing layer composition] parts by weight binder : (See Table 1 for type) 10 Dye: (See Table 1 for type and amount used) Solvent: Toluene 100 Methyl ethyl ketone 100 These sublimation-type thermal transfer media were printed on the image receiving member a number of times in the same manner as in Example 1, and the image density (Macbeth densitometer RD-51) was used.
4), gloss of the image and missing dots were observed.

As can be seen from Table 2, the sublimation type thermal transfer medium of the present invention can provide a stable image density even after printing many times, and is excellent in image gloss and dot missing characteristics.

Effects As described above, by keeping the concentration of the dye contained in the dye transfer contributing layer close to the saturation solubility of the binder as in the present invention, the surface of the dye transfer contributing layer can be kept smooth, As a result, it is possible to provide a sublimation-type thermal transfer medium that can be printed a number of times, which can prevent deterioration in image quality and has a glossy and sufficient image density.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyuki Uemura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP 2-586 (JP, A) JP 1-1141092 (JP, A) JP-A-1-286892 (JP, A) JP-A-2-24192 (JP, A) JP-A-2-192992 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] 1. A sublimation-type thermal transfer medium comprising a substrate and a dye supply layer and a dye transfer contributing layer each containing a sublimable dye contained in an organic binder in order from the substrate side. When the supply layer and the dye transfer contributing layer are formed as a single layer on the substrate with the same amount of adhesion in each of the formulations, each is superimposed on a separate image receiving layer, and the same thermal energy is applied to both. The amount of dye transferred to each image receiving layer is in the relationship of dye supply layer> dye transfer contributing layer, and the content of the dye contained in the dye transfer contributing layer is the saturation solubility of the dye in the organic binder. To
A sublimation-type thermal transfer medium characterized by being contained at a ratio of 95 to 100 when 100 is used.