JP2837673B2 - Sublimation type thermal transfer media - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sublimation-type thermal transfer medium, and more particularly to a sublimation-type thermal transfer recording medium for magenta multiple printing using a red-based and violet-based sublimable dye.

2. Description of the Related Art In recent years, the demand for full-color printers has been increasing year by year, and the recording methods of the 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 heat recording 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, in order to replenish the dye consumed in the upper layer (free surface layer) of the dye transfer contributing layer by printing, the dye is released from the dye supply layer to the lower layer of the dye transfer contributing layer so that the dye can be easily supplemented. It has been proposed to design each layer so that the function is in the relationship of dye supply layer> dye transfer contributing layer (see Japanese Patent Application No. 63-62866). However, although this method gives good results with monochromatic dyes, when forming a magenta color by mixing two colors of red and violet,
A color tone shift occurs, and in particular, when the violet color is excessively transferred, there is a disadvantage that the color tone shift becomes remarkable.

Object The present invention provides a sublimation type thermal transfer recording medium for magenta multi-time printing using a red-based and violet-based sublimable dye. It is an object of the present invention to provide a sublimation type thermal transfer recording medium in which the color tone does not change.

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 transfer contributing layer formed by dispersing a sublimable dye in an organic binder in order from the substrate side. In a sublimation type thermal transfer medium formed by laminating, the dye supply layer contains a red-based and violet-based sublimable dye, and the entire dye transfer-contributing layer contains only a red-based sublimable dye, or the dye-transfer-contributing layer It has been found that the above object can be attained by providing a sublimation type thermal transfer medium characterized in that only the layer on the free surface side in contact with the image receiving member contains only the red-based sublimable dye.

In a sublimation type thermal transfer medium for multiple printing as a preferred embodiment of the present invention, the dye supply layer contains undissolved particulate dyes of various sublimable dyes, but the dye transfer contributing layer contains undissolved particulate dyes. It is characterized by the absence of a dye.

By having undissolved particulate dye in the dye supply layer as a dye supply source, good multi-time printing characteristics can be maintained even in high concentration areas, and the dye concentration in the dye supply layer is kept constant for each printing. Can be.

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. The present invention has been improved so that the invention can be suitably applied to magenta multiple printing.

Currently, full colors are formed in yellow, magenta, and cyan. Here, at present, there is no single good magenta dye for sublimation transfer, and it is generally formed of a mixed color of a red dye and a violet dye. Therefore, when the color balance between magenta red and violet is lost during multiple recordings, color shift occurs in the entire full-color image, causing a problem. In addition, when the color balance between red and violet is disrupted, the excess of violet, which is a sub-component, between red excess and violet excessively causes a noticeable color tone shift in visual observation.

Here, according to the method disclosed in Japanese Patent Application No. 63-62866, the mixing ratio of red and violet in the dye transfer contributing layer and the dye supply layer is formed at the same mixing ratio as one time as a magenta transfer member, An ink layer was formed with the relationship of the dye diffusion coefficient of the dye transfer contributing layer <the dye diffusion coefficient of the dye supply layer and the relationship of the dye concentration of the dye transfer contributing layer <the dye concentration of the dye supply layer, and printing was performed many times. In each case, a color shift occurs due to an imbalance in the mixing ratio of red and violet each time.

The main cause is considered to be that the ratio of the red-based sublimable dye and the violet-based sublimable dye in the dye transfer contributing layer which directly contributes to image formation differs for each printing.

In the printing operation, the dye supply layer and the dye transfer contributing layer have the following relationship. That is, (i) the amount of dye supplied from the dye supply layer to the dye transfer contribution layer is determined by the concentration gradient of the diffusion coefficient between the dye supply layer and the dye transfer contribution layer. (Fick's Law) (ii) The concentration gradient in (i) is not a dye content gradient but a gradient of the amount of dye that is molecularly diffused in each layer.

(Iii) Therefore, the amount of undissolved particulate dye in the dye supply layer does not contribute to the concentration gradient described in (i).

(Iv) From the above, in order to supply the dye from the dye supply layer to the dye transfer contributing layer at a constant ratio (ratio of red and violet showing a good magenta color) each time red and violet are supplied, At each temperature during printing, red and violet must always be dissolved at a constant ratio in the dye supply layer.

It is very difficult to control the solubility of red and violet in (v) and (iv). Therefore, the ratio of red and violet when dye is supplied from the dye supply layer to the dye transfer contributing layer is different every time, and as a result, the ratio of red and violet in the initial stage of the dye transfer contributing layer changes with each printing. However, it also changes at the time of transfer, causing color misregistration.

(Vi) In this case, in particular, if the supply and transfer of violet as an accessory component is excessive, visual color shift becomes remarkable.

In view of the above, the dye contained in the dye transfer contributing layer may be composed of only the red sublimable dye which is the main component of the initial magenta color (or only the layer on the free surface side in the dye transfer contributing layer may have the red dye). Only the sublimation dye may be contained), and it is possible to prevent the color shift due to excessive violet from becoming prominent, and it is possible to print many times a good magenta color with little color shift at a visual level.

 Hereinafter, each material will be described more specifically.

The thickness of the transfer contributing layer is generally 0.05 to 5 μm, preferably 0.1 to 2 μm. The thickness of the dye supply layer is generally 0.1 to 20 μm, preferably 0.5 to 5 μm.

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

The sublimable dye is a dye that sublimates or vaporizes at 60 ° C. or higher, and may be any one that is mainly used in thermal transfer printing such as disperse dyes and oil-soluble dyes.Examples of red sublimable dyes include CI. Disperse Red 1,4,6,1
1,15,17,55,59,60,73,83 etc. and CI Solvent Red
There are 23, 25, 27, 135, 81, 18, 19, 143, 146, 182, etc., and examples of violet-based sublimable dyes include CI Disperse Violet 4, 13, 36, 56, 31, etc. and CI Solvent Violet 13, 36, etc. No.

Thermoplastic or thermosetting resin is used for the binder used in the dye transfer contributing layer and the dye supply layer, for example, vinyl chloride resin, vinyl acetate resin, polyamide, polyethylene, polycarbonate, polystyrene, polypropylene, acrylic resin Phenolic resin, polyester, polyurethane, epoxy resin, silicone resin, fluorine resin, butyral resin, melamine resin, natural rubber, synthetic rubber, polyvinyl alcohol, and cellulose resin. These resins can be used singly, but a mixture of several resins or a copolymer may be used.

Further, when making a difference in the glass transition or softening temperature between the dye transfer contributing layer and the dye supply layer, a resin having a glass transition temperature of 0 ° C. or less, or a softening temperature of 60 ° C. or less or a natural or synthetic rubber is used for the dye supply layer. Organic binders are preferred, specifically, syndiotactic 1,2-polybutadiene (JSR RB810,820,830 Nippon Synthetic Rubber as a commercial product); olefin copolymers and terpolymers containing acids or non-acidic acids (commercially available) Dexon XEA-7, Dexon Chemical); ethylene-vinyl acetate copolymer (400 & 400A, 405,430 as commercial products, Allied Fibers &
Plastics; P-3307 (EV150), P-2807 (EV250),
Mitsui DuPont Polychemical); low molecular weight polyolefin polyol and its derivatives (Polytail H, HE Mitsubishi Kasei Kogyo as commercial products); brominated epoxy resin (YDB-3)
Novolak type epoxy resin (YDCN-701,702,703 Toto Chemical); Thermoplastic acrylic solution (Tynalnal LR1075,1080,1081,1082,106)
3,1079 Mitsubishi Rayon); thermoplastic acrylic emulsion (LX-400, LX-450, Mitsubishi Rayon); polyethylene oxide (Alcox E-30,45, Alcox R-150,
Caprolactone polyol (Placcel H-1,4,7, Daicel Chemical Industries); and the like, in particular, polyethylene oxide and polycaprolactone polyol are practically useful. It is preferable to use a thermoplastic or thermosetting resin for the dye transfer contributing layer in a form mixed with one or more of the above.

The dye content of the transfer contributing layer is usually about 5 to 80%, preferably about 10 to 60%.

The dye content of the dye supply layer is preferably from 5 to 80%. However, when a dye concentration gradient is provided between the dye transfer contribution layer and the dye supply layer, the dye content is , 1.1 to 5 times, preferably 1.5 to 3 times.

As for the state of the dye in the dye supply layer, it is desirable that the non-dissolved particulate dye is present in order to keep the dye concentration in the dye supply layer constant and to show good printability many times even in a high concentration part.
The presence or absence of the formation of the non-dissolved particulate dye in the binder can be easily identified by an electron microscope (2000 times) after the formation of the dye supply layer. More simply, it can be easily identified by visually judging the transparency.

Further, the particle size of the undissolved particulate dye varies depending on the thickness of the dye supply layer, but 0.01 μm to 20 μm, preferably 1.0 μm
m to 5 μm is desirable.

Further, the dye state in the dye transfer contributing layer exists in a monomolecular state which actually contributes to the transfer to prevent occurrence of transfer density unevenness and a dye concentration gradient between the dye transfer contributing layer and the dye supply layer. Is desirable from the viewpoint of maintaining the stability.

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

So far, an example in which the dye layer is divided into two layers has been described. However, if an appropriate difference in dye transfer amount is generated and the function separation intended by the present invention can be achieved, the dye layer may be formed into a multilayer of two or more layers. It is possible.

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, a relatively heat-resistant polyester, polycarbonate, triacetyl cellulose, nylon, polyimide, aromatic polyamide or other resin 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 the insulator and the good conductor. A support on which a conductive 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 conversion material such as carbon, or 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 [Prescription of Dye Transfer Contribution Layer] Part by weight Polyvinyl butyral resin BX-110 (manufactured by Sekisui Chemical Co., Ltd.) Sublimable dye MS Red G 7.5 (manufactured by Mitsui Toatsu Chemicals, Inc.) Solvent Toluene 95 methyl ethyl ketone 95 [Prescription of Dye Supply Layer] Parts by weight Polyvinyl butyral resin BX-11 (manufactured by Sekisui Chemical Co., Ltd.) Polyethylene oxide 9 (Alcox R400) Sublimable dye MS Red G 4 (manufactured by Mitsui Toatsu Chemicals, Inc.) Sublimable dye Macrolex Red Violet R 2 (manufactured by Bayer Corp.) Solvent Toluene 95 Methyl ethyl ketone 95 After dispersing the composition of the above formulation in a ball mill for 24 hours, 8.5 μm polyimide film substrate (Toray DuPont) as shown in FIG. The above-mentioned ink composition for dye supply layer 4 was applied to a thickness of 3.00 μm on a wire bar 1 using a wire bar, and then the dye transfer of the above formulation was further applied thereon. The ink composition for the contributing layer 5 was applied so as to have a film thickness of 1.00 μm to form an ink layer 2, thereby producing a sublimation transfer medium.

Example 2 [Formulation of Dye Transfer Contributing Layer] Part by weight Polyvinyl butyral resin BX-1 10 Sublimable dye Solvent Red 52 7.5 Solvent Toluene 95 Methyl ethyl ketone 95 [Formulation of dye supply layer] Part by weight Polyvinyl butyral resin BX-11 Polyethylene oxide 9 (Alcox R400) Sublimable dye Solvent Red 52 4 Sublimable dye Solvent Violet 36 2 Solvent Toluene 95 Methyl ethyl ketone 95 After dispersing the composition of the above formulation in a ball mill for 24 hours, 8.
A 5 μm polyimide film (manufactured by Toray Dupont Co., Ltd.) is coated with the above-mentioned ink composition for a dye supply layer using a wire bar so as to have a thickness of 3.00 μm. The material was applied to a thickness of 1.00 μm to form a sublimation transfer medium.

Example 3 [Prescription of Dye Transfer Contributing Layer] Part by weight Polyvinyl butyral resin BX-1 10 Sublimable dye Kayaset Red B 7.5 (manufactured by Nippon Kayaku Co., Ltd.) Solvent Toluene 95 Methyl ethyl ketone 95 [Prescription of dye supply layer] Part by weight Polyvinyl butyral resin BX-11 Polyethylene oxide 9 (Alcox R400) Sublimable dye Kayaset Red B4 Sublimable dye Kayaset Violet 318 2 (Nippon Kayaku Co., Ltd.) Solvent Toluene 95 Methyl ethyl ketone 95 24 After dispersion with ball mill for 8 hours, 8.
A 5 μm polyimide film (manufactured by Toray Dupont Co., Ltd.) is coated with the above-mentioned ink composition for a dye supply layer using a wire bar so as to have a thickness of 3.00 μm. The material was applied to a thickness of 1.00 μm to form a sublimation transfer medium.

Comparative Example 1 In the ink composition for a dye transfer contributing layer of Example 1,
5 parts by weight of MS Red G as a sublimable dye and Macrolex Red
A sublimation transfer medium was formed in the same manner as in Example 1 except that 2.5 parts by weight of Violet R was used.

Comparative Example 2 In the ink composition for a dye transfer contributing layer of Example 2,
5 parts by weight of Solvent Red 52 as a sublimable dye and Solven
A sublimation transfer medium was formed in exactly the same manner as in Example 2 except that 2.5 parts by weight of t Violet 36 was used.

Comparative Example 3 In the ink composition for a dye transfer contributing layer of Example 3,
5 parts by weight of Kayaset Red B as sublimation dye and Kayaset
A sublimation transfer medium was formed in the same manner as in Example 3 except that 2.5 parts by weight of Violet 318 was used.

Comparative Example 4 In Example 1, MS Red G of the dye transfer contributing layer was replaced with Macr
A sublimation transfer medium was formed in the same manner as in Example 1 except that olex Red Violet R was used.

The presence of undissolved particulate dye in the dye supply layer was determined by using a scanning electron microscope S-310A (manufactured by Hitachi, Ltd.).
As a result of confirming at 2000 times, Examples 1, 2, 3 and Comparative Example 1,
It was present in a couple of all.

Further, since the solubility of the biolet dye in Example 1 to the solvent used is high, the dye transfer contributing layer dissolves into the dye transfer contributing layer from the dye supply layer during coating and drying, and as a result, the free surface of the dye transfer contributing layer is free. It was confirmed by cross-sectional observation that only a part of the layer on the side was composed only of the red dye.

Next, energization transfer was performed in the following manner. As the image receiving member 3, an image receiving paper of supply VY-S100 for Hitachi Video Printer VY-50, which is an image receiving paper for sublimation type thermal transfer recording, was used.

As shown in FIG. 1, the thermal energy was applied to the sublimation transfer media of Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 using the thermal head 6 as the printing condition.
The following results were obtained as a result of performing printing many times at the same location at 2.5 mJ / dot.

Effect As described above, the sublimation type thermal transfer body of the present invention in which the ink layer configuration is improved, the printing density does not substantially decrease even if the printing is performed a large number of times, and the color tone shift is acceptable at a visual level. It has a multi-time printing characteristic.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the structure of a sublimation type thermal transfer body of the present invention. DESCRIPTION OF SYMBOLS 1 ... Support, 2 ... Ink layer 3 ... Image receiving body 4, ... Dye supply layer 5 ... Transfer contributing layer, 6 ... Thermal head

──────────────────────────────────────────────────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-A-1-103496 (JP, A) JP-A-Hei JP-A-1-225593 (JP, A) JP-A-1-286892 (JP, A) JP-A-2-2073 (JP, A) JP-A-2-2077 (JP, A) JP-A-2-2078 (JP, A A) JP-A-62-255188 (JP, A) "Color Handbook of Color Chemistry" edited by The Japan Society of Color Science (55-7-31), University of Tokyo Press, pp. 147-157 (58) Fields studied (Int. 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 having a sublimable dye dispersed in an organic binder in order from the substrate side. Sublimation type thermal transfer wherein the supply layer contains a red-based and violet-based sublimable dye, and at least the layer on the free surface side of the dye transfer-contributing layer which is in contact with the image receptor contains only the red-based sublimable dye. Medium.