JP3003938B2 - Sublimation type thermal transfer body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sublimation type thermal transfer member.

[Prior art] In recent years, the demand for full-color printers has been increasing year by year, and as recording methods for the full-color printers, there are an electrophotographic method, an ink jet method, a thermal transfer method, and the like. Thermal transfer systems are often used.

This thermal transfer system is a thermal transfer recording medium (a so-called color ink sheet) in which a colorant is dispersed in a heat-fusible substance or a sublimable dye is dispersed in a resin binder on a substrate. Overlay the image receiving sheet on the ink layer surface of
This is a recording method in which thermal energy controlled by an electric signal of a laser, a thermal head, or the like is applied from the recording medium side, and the ink in that portion is heat-melt-transferred or sublimated onto an image-receiving sheet to form an image.

The thermal transfer recording method is roughly classified into a heat-melt transfer type and a sublimation transfer type according to the type of recording medium used. In particular, in the latter case, dyes are used in principle in response to heat energy from a thermal head or the like. It is considered that the method is most suitable for a full-color printer because it has an advantage that a halftone can be easily obtained due to transfer in a monomolecular state, and that the gradation can be adjusted arbitrarily.

However, in this sublimation type thermal transfer recording method, in order to form one full-color image, selective thermal printing is performed for each ink sheet using one yellow, magenta, and cyan (black) ink sheet. Thereafter, since unused portions remain, they are discarded, which has a drawback of high running cost.

Therefore, in order to remedy this drawback, a method of printing and recording a large number of times by repeatedly using the same ink sheet has been used in recent years. Specifically, a constant speed mode method in which printing is performed repeatedly while the ink sheet and the image receiving sheet are running at a constant speed, and the speed of the image receiving sheet is set to n times the speed of the ink sheet (n>
There are two methods, the n-times mode method, in which the printing is repeated while the both sheets are running in 1).

In the latter n-times mode method, printing is performed a large number of times by a relative speed method in which the overlapping portion between the used portion of the ink layer and the used portion of the ink layer is shifted little by little. In the n-times mode method, the larger the value of n, the more advantageous in terms of cost. In such a multiple-time recording method using the n-times mode method, a part of the unused portion of the ink layer is always supplied every time printing is performed, so that the multiple-time recording method using the constant speed mode method is merely a repeated use of the used portion. There is an advantage that the variation of the remaining ink amount due to the recording history can be reduced as compared with the method (IEEE Cvol J
70-C, No. 11, pages 1537 to 1544, November 1987).

However, in the sublimation type thermal transfer recording system, the sublimation and evaporation reactions are basically zero-order reactions, and despite the fact that the amount of dye that can sufficiently withstand multiple uses in the n-fold mode method is contained in the ink layer. , N, that is, as the relative speed of the recording medium decreases, the transfer density particularly in the high image density portion decreases, so that satisfactory multiple-time printing is difficult.

Accordingly, the present applicant has superimposed an image receiving sheet on an ink layer of a sublimation type thermal transfer recording medium having an ink layer in which a sublimable dye is dispersed in a resin binder in the form of particles in a resin binder, and the [speed of image receiving sheet] ] / [Speed of recording medium]> sublimation type thermal transfer body for performing thermal printing from the recording medium side and sublimate-transferring the dye in the ink layer to the image receiving sheet on the image receiving sheet with both running under the condition of 1. A method was proposed.

The present applicants have studied the use of a recording medium many times, and found that when printing is first performed many times in the constant velocity mode method, the cause of the decrease in the transfer image density due to the remaining amount of the dye is the gas barrier property of the binder in the ink layer. And proceeded with the research.
That is, in order to form the ink layer of the color sheet for multi-printing, the adhesion amount of the dye and the binder resin is greatly increased as compared with the usual one-time ink layer, and as a result, the film thickness is increased.

When the dye is dissolved or finely dispersed in the binder in the ink layer having the increased film thickness, the dye in the lower layer of the ink layer is heated for several ms due to the gas barrier property of the binder during the heating printing.
Within a short period of time, diffusion movement is not possible up to the surface portion, and consequently does not contribute to the transfer density. Therefore, the transfer amount of the dye is determined only by the dye existing near the upper layer interface which actually contributes to the transfer of the ink layer having a limited film thickness.

Further, at the time of print transfer, the dye near the interface of the upper layer of the ink layer is reduced by contributing to the transfer, and the supply and diffusion of the dye are insufficient from the lower layer due to the gas barrier property of the binder. No density is formed, and as a result, the dye concentration in the lower layer becomes higher than the level at the interface of the upper layer, and the dye concentration at the interface of the upper layer contributing to transfer is remarkably reduced.

In this way, the dye concentration in the upper layer portion of the ink layer decreases as printing is repeated. It is considered that the following phenomenon of a decrease in transfer density appears remarkably in the transfer portion.
For such a reason, it is considered that the transfer density characteristic changes as if it were a primary reaction, although the sublimation reaction itself is a zero-order reaction. Therefore, based on this idea, the present inventors should make the dye in the ink layer exist in a dissolved state for the purpose of replenishing the decrease in the dye concentration in the upper layer of the ink layer with the molecular dye from the particulate dye. Instead, a thermal transfer recording medium in which the dye was present in the form of solid particles was developed. Further, as shown in FIG. 1 (where 1 is a substrate, 2 is an ink layer, 3 is an image receiving sheet, and 4 is a thermal head), the speed of the image receiving sheet is set to n times (n
By combining with the n-times mode method in which printing is repeatedly performed while both sheets are running in the condition of > 1), it is possible to print more excellently many times.

However, when a particulate dye is contained in the ink layer, the bond between the dye and the binder is not uniform as compared with the dissolving type, so that during storage, the dye having a weak bond with the binder may be used on the surface of the ink layer. When the value of n is small (in the initial case) in the multiplicity (multiple printability) of the n-times mode method, molecules from the particulate dye As a result of an increase in the amount of dye released, the recording density tends to show a higher value than the target recording density, and therefore, there is a disadvantage that the multiplicity is eventually reduced.

[Problems to be Solved by the Invention] Under these circumstances, the present invention has good storage stability, sensitivity is appropriate, and there is no decrease in transfer density even after printing many times.
It is another object of the present invention to provide a sublimation-type thermal transfer member which does not cause troubles such as running failure due to frictional contact between the ink layer of the ink sheet and the receiving layer of the image receiving sheet and peeling of the ink layer.

[Means for Solving the Problems] The present inventors have intensively studied to solve the above-mentioned problems, and as a result, on the ink layer dispersed in the form of particles, lubricity,
The present inventors have found that it is effective to provide an over layer in which a substance having releasability is dispersed, and have reached the present invention.

That is, the present invention provides an ink layer in which a sublimable dye having a particle diameter of 1.0 to 20 μm is dispersed in an organic binder in the form of particles in an organic binder, and the dye is present in the form of individual particles, on the substrate, and A sublimation-type thermal transfer member characterized by laminating a lubricating layer in which a substance having lubricity or releasability is dispersed in an organic binder.

The sublimable dye used in the ink layer is a dye that sublimates or vaporizes at 60 ° C. or higher, and may be any dye mainly used in the field of thermal transfer recording such as a disperse dye or an oil-soluble dye, such as CI Disperse Yellow. 1,3,8,9,16,41,
1,4,6,1 of CI disperse thread such as 54,60,77,116
CI Solvents such as 1,15,17,55,59,60,73,83, CI Disperse Blue 3,14,19,26,56,60,64,72,99,108, CI Solvent Yellow 77,116 Red 23,2
CI Solvent Blue 36,83,105 and the like. These dyes are used alone or as a mixture of several kinds. The dye concentration in the ink layer is 5 to 80%, preferably 10 to
It is about 60%.

The particle size of the dye is 1.0 to 20 μm, preferably 1.0 to 10 μm, and when the particle size of the dye particle is larger than the thickness of the ink layer, irregularities occur on the surface of the ink layer, which tends to deteriorate the quality of the transferred image. . Therefore, the particle size of the dye particles used in the thermal transfer recording medium of the present invention is large enough to enable good multi-printing, and at the same time, the ink layer is formed so as not to cause irregularities on the surface of the ink layer. It is preferably smaller than the film thickness.

Further, the thickness of the ink layer is 1 to 20 μm, preferably 1 to 8 μm.
It is about μ.

Examples of lubricating or releasable substances (lubricating substances) include, for example, petroleum-based lubricating oils such as liquid paraffin, hydrogen halides, diester oils, silicone oils, synthetic lubricating oils such as fluorosilicone oils, and various modified oils. Silicone oils (epoxy-modified, amino-modified, alkyl-modified, polyether-modified, etc.), silicone-based lubricating substances such as copolymers of organic compounds such as polyoxyalkylene glycol and silicone, and various fluorine-based surfactants such as fluoroalkyl compounds And waxes such as paraffin wax and polyethylene wax, higher fatty acids, higher fatty alcohols, higher fatty acid amides, higher fatty acid esters, higher fatty acid salts and the like.

The content of the substance having lubricity or releasability in the dye transfer contributing layer is preferably 5 to 30% by weight. The content is 5%
If it is less than 30%, the releasability or the effect of preventing fusion are insufficient. On the other hand, if it exceeds 30%, sensitivity and storage stability are reduced.

As the binder used for the ink layer and the release layer, various thermoplastic or thermosetting resins are used, for example, vinyl chloride resin, vinyl acetate resin, polyamide, polyethylene, polycarbonate, polystyrene, polypropylene, acrylic resin, and phenol. Examples include resin, polyester, polyurethane, epoxy resin, silicone resin, fluorine resin, butyral resin, melamine resin, natural rubber, synthetic rubber, polyvinyl alcohol, celluloses, and resins. These resins can be used singly, but a mixture of several resins or a copolymer may be used.

The thickness of the release layer is 0.1 to 2.0 μm, preferably 0.1 to 1.0 μm.
m is preferred.

As the substrate, films such as condenser paper, polyester film, polystyrene film, polysulfone film, polyimide film and polyamide film are used.

The provision of a heat-resistant lubricating layer on the back surface of the substrate can be appropriately performed as necessary.

As the thermal printing means, in addition to a thermal head, a thermal printing plate, a laser beam (in this case, a substrate that generates heat by absorbing the laser beam) or an electrically conductive substrate and / or ink layer is used. A method utilizing Joule heat can be used. Of these, the so-called energetic thermal transfer system using Joule heat generated in a medium is best known, for example, US Pat. No. 4,103,066,
It is described in many documents such as 4060, JP-A-57-11080, and JP-A-59-9906.

When used in the current transfer method, as a substrate, a resin such as polyester, polycarbonate, triacetyl cellulose, polyamide, polyimide, and aromatic polyamide having relatively high heat resistance, aluminum, copper, iron, tin, zinc, nickel, Metal powders such as molybdenum and silver and / or conductive powders such as carbon black are dispersed to adjust the resistance to a value between an insulator and a good conductor, and the above-mentioned conductive metal is deposited on these substrates. Alternatively, a material obtained by sputtering may be used. The thickness of these substrates is desirably about 2 to 15 microns in consideration of the Joule heat conduction efficiency.

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

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto.

The amounts (parts) of the components described in the examples are parts by weight.

(Receptive layer formulation) Linear saturated polyester resin Byron 200 [Toyobo Co., Ltd.] 20 parts Isocyanate malonate L 2 parts Amino-modified silicone oil KF-393 [Shin-Etsu Silicone Co., Ltd.] 1 part Epoxy-modified silicone oil X-22 -343 [manufactured by Shin-Etsu Silicone Co., Ltd.] 1 part Toluene MEK = 1/176 part was formed on a 150 µm synthetic paper (manufactured by Oji Yuka Synthetic Paper Co., Ltd.) using a wire bar coating to form an 8 µm thick coating.
The composition was cured at 60 ° C. for 48 hours to obtain an image receiving paper.

The printing conditions are as follows:
Print recording was performed under the following printing conditions.

Applied energy: 3.0 mJ / dot Thermal head: 6 dots / mm portion Glaze type Speed ratio between image receiving paper and recording medium: n = 1 to 15 Example 1 6 μm having a 1 μm thick silicone resin heat-resistant layer on the surface as a substrate An ink layer is formed on a thick aromatic polyamide film (application surface is the polyamide film side) so that the dye adhesion amount is 3.8 g / m ^2, and a release layer 0.5 μm is further formed thereon.
Thus, a sublimation type thermal transfer member was obtained.

(Ink layer composition) parts by weight Polyvinyl butyral resin BX-1 [manufactured by Sekisui Chemical Co., Ltd.] 10 Sublimable dye Kayaset Blue 714 [manufactured by Nippon Kayaku Co., Ltd.] 15 Methyl ethyl ketone 95 Toluene 95 (Release layer composition Product) parts by weight polyvinyl alcohol resin KM-11 [manufactured by Nippon Synthetic Chemical Industry Co., Ltd.] 10 Polyethylene wax Sunwax E-300 [manufactured by Mitsui Chemicals, Inc.] 2 Alkylolamide activator for wax emulsification Prophan 2012E [Manufactured by Sanyo Chemical Industry Co., Ltd.] 0.4 water 190 Example 2 In Example 1, (release layer composition) parts by weight hydroxyethylcellulose Natrosol 250E type [manufactured by Hercules Co., Ltd.] 10 Polyethylene wax Sunwax E-300 [Manufactured by Sanyo Chemical Industries, Ltd.] 2 Polyoxyethylene nonylphenyl ether nonipol 100 for wax emulsification [Sanyo Chemical Business Ltd.] 0.5 except that using 20% potassium hydroxide aqueous solution 0.15 Water 490 give the sublimation thermal transfer layer in Example 1.

Example 3 In Example 1, (ink layer composition) parts by weight Cellulose acetate butyrate resin CAB-381-0.5 [manufactured by Kodak Co., Ltd.] 10 Sublimable dye MS Red G [Mitsui Toatsu Dye Chemical Co., Ltd.] 15) methyl ethyl ketone 45 toluene 45 (release layer composition) parts by weight methylcellulose 10 paraffin wax emulsion hydrin P-7 [manufactured by Chukyo Yushi Co., Ltd.] 10 water 65 was used in the same manner as in Example 1 except that A sublimation type thermal transfer body was obtained.

Comparative Example 1 A sublimation-type thermal transfer member having no release layer in Example 1 was formed.

Comparative Example 2 In Example 1, 2 parts by weight of polyethylene wax sunwax E-300 was further added to the ink composition, and only the ink layer was formed without providing a release layer, thereby forming a sublimation type thermal transfer member.

Comparative Example 3 A sublimation-type thermal transfer member was obtained in the same manner as in Example 1, except that the release layer composition in which the polyethylene wax sunwax E-300 and Prophan 2012E were omitted was applied to the release layer.

Example 4 Except that the release layer composition in Example 3 was changed to 190 parts by weight of polyvinyl alcohol resin KM-11 10 polyether-modified silicone oil KF351 (A) [manufactured by Shin-Etsu Chemical Co., Ltd.] In the same manner as in No. 3, a sublimation type thermal transfer member was obtained.

Comparative Example 4 In Example 3, a sublimation-type thermal transfer member having no release layer was formed.

Comparative Example 5 In Example 3, 2 parts by weight of polyether-modified silicone oil KF351 (A) was added to the ink composition, and only the ink layer was formed without providing a release layer, thereby forming a sublimation type thermal transfer member.

Comparative Example 6 A sublimation-type thermal transfer member was obtained in the same manner as in Example 1, except that the release layer composition in which the paraffin wax emulsion hydrin P-7 was omitted was applied to the release layer in Example 3.

Further, in order to confirm the dye state of the ink layers of Examples 1 to Comparative Examples 1 to 6, observation was performed at a magnification of 2000 using a scanning electron microscope S-310A (manufactured by Hitachi, Ltd.). And the average particle size of the dye particles was 5 μm in Example 1.

For each of the thermal transfer bodies obtained in Examples 1 to 4 and Comparative Examples 1 to 6, a temperature of 60 ° C. and a humidity of 50
%, Before and after storage for 100 hours, the state of background contamination at n = 1; and running failure at 7 × speed, that is, the state of ink layer, thermal transfer, and ink layer breakage; and recording when the speed ratio is changed. The change in concentration was observed, and the results are shown in Table 1.

No background dirt ○, Yes ×, No running failure ○, Slightly present, Yes (recording not possible) ×, Multi-property 15 times good ○, About 7 times △, No multi-property × The dirt and running defects are visually judged According to Also,
The multiplicity was measured with a reflection densitometer using RD-918 (Macbeth), and it was possible to reduce the re-high density by 15%.

[Effects of the Invention] As described above, the sublimation-type thermal transfer body of the present invention contains a particulate dye, and by further providing a slip layer thereon, the surface deposition of the dye can be prevented by the slip layer. In addition, the excess recording density in the initial stage can be reduced, so that the multi-characteristics can be improved, the smoothness can be improved, and the running state can be smooth.

In particular, when a slip agent having a low melting point or a low glass transition temperature is mixed into the slip layer, sensitivity loss (recording density decrease) due to the provision of the slip layer can be reduced.

[Brief description of the drawings]

FIG. 1 shows an n-type sublimation type thermal transfer member suitable for use in the present invention.
FIG. 4 is an explanatory diagram of a double mode method. DESCRIPTION OF SYMBOLS 1 ... Base, 2 ... Ink layer, 3 ... Image receiving sheet, 4 ... Thermal head.

Continued on the front page (72) Inventor Naoya Moroboshi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hiroyuki Uemura 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company In Ricoh (56) References JP-A-1-225593 (JP, A) JP-A-2-25389 (JP, A) JP-A-2-50888 (JP, A) JP-A-2-89688 (JP, A) ) Patent 2502683 (JP, B2)

Claims (2)

(57) [Claims] 1. A particle size on a substrate in order from the substrate side.
An ink layer in which a sublimable dye of 1.0 to 20 μm is dispersed in an organic binder in the form of particles and the dye is present in the form of individual particles, and a substance having lubricity or releasability is dispersed in the organic binder. A sublimation-type thermal transfer member characterized by laminating a slippery layer formed thereon. 2. The sublimation type thermal transfer member according to claim 1, wherein the lubricating layer contains a lubricating agent having a lower melting point or a lower glass transition temperature than the organic binder.