JPH0780353B2 - Thermal sublimation transfer sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat-sensitive sublimation transfer sheet using a heat-sensitive sublimation transfer layer forming ink composition (hereinafter simply referred to as dye layer ink).

(Prior Art) Conventionally, a heat-sensitive sublimation type transfer sheet using a heat sublimation transferable dye (hereinafter simply referred to as a dye or a sublimation dye) has a dye suitable for such a purpose added to an ink vehicle containing a binder resin. The dye layer ink is prepared by dispersing the dye as finely as possible by a grinding means such as a ball mill or a sand mill, and the dye layer ink is applied to a base sheet, and the heat-sensitive sublimation transfer layer having a predetermined length is formed on the base sheet. Hereinafter, this is simply referred to as a dye layer). The heat-sensitive sublimation type transfer sheet thus obtained is superposed with a heat-sensitive sublimation type transfer sheet (hereinafter simply referred to as an image receiving sheet) having a dye receiving layer capable of receiving a dye, and from which side A monochromatic or full-color image is formed on the image-receiving sheet by the dyes sublimated from the dye layer by being heated according to the image signal by a heating means such as a thermal head.

(Problems to be Solved by the Invention) The image forming method using the heat-sensitive sublimation type transfer sheet as described above has a problem that a specific image receiving sheet is used.
For example, a color image having continuous gradation can be obtained from an electric signal, and has been attracting attention in recent years. However, in the dye layer of the heat-sensitive sublimation transfer sheet, the sublimable dye is dispersed in the binder resin in the form of particles, and the heating time by the thermal head is only a few msec.
In order to heat and sublimate the dye molecule in such a state because it is short, the interaction in the crystal is broken, and further heat energy exceeding the interaction with the binder resin is given to the dye molecule to sublimate, It must be dyed to the image receiving sheet. Therefore, when a dye is contained in a high proportion to the binder resin in order to obtain a high density color image requiring high energy, a high density image to some extent can be obtained, but at a high density. Due to the existing dispersed dye, the binding force between the base sheet and the dye layer of the heat-sensitive sublimation type transfer sheet becomes weak, and when peeled off after printing with a thermal head or the like on the image receiving sheet, the dye layer becomes a binder. The phenomenon in which the resin is taken on the image-receiving sheet is likely to occur, and the dye is expensive in price. From the viewpoint of OA equipment and home use, it is impossible to add more dye than necessary. There are various drawbacks such as economical disadvantage.

On the other hand, a method of obtaining a dye layer by coating and drying a base sheet using a supernatant liquid for the transparency of an ink composed of a dye, a binder resin and a solvent has been proposed. In this case, the obtained dye layer may be one in which dyes are molecularly dispersed. In such a case, a higher concentration can be obtained with the same applied energy as compared with the dye layer.

However, in such a case, when the temperature becomes a little low in the state of the ink, the solubility of the dye is lowered, so that the dye concentration in the supernatant is lowered, and the stability of the ink is decreased. Is lacking in. Further, in an extreme case, there arises a problem that a dissolved dye is deposited mainly on the precipitated dye particles.

Therefore, it has been difficult to form a full-color image having a sufficient color forming property and a sufficient continuous gradation property with a heat-sensitive sublimation transfer sheet using a conventional sublimable dye.

(Means for Solving Problems) As a result of earnest research to solve the above-mentioned drawbacks of the prior art, the present inventor has determined that the dye layer of the heat-sensitive sublimation transfer sheet is a specific binder resin, a specific sublimable dye and By using a combination of specific solvents, the drawbacks of the prior art as described above are sufficiently solved, and the heat-sensitive sublimation transfer sheet has high stability, high heat sensitivity, and direct silver salt photography. The present invention has been completed by finding that an image such as a full curler photograph having such continuous gradation and sufficient coloring property can be obtained, and the durability of the obtained image is also sufficient.

That is, the present invention provides a dye layer on a base sheet using a dye layer ink characterized in that an ink consisting of a heat-sensitive sublimable dye, a binder resin and a solvent is substantially completely dissolved. It is a heat-sensitive sublimation type transfer sheet.

The dye layer of the heat-sensitive sublimation transfer sheet comprises a binder resin and a sublimable dye, and the binder resin is selected from the group consisting of ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose and cellulose acetate butyrate. Cellulose derivative, vinyl resin, polyacrylamide resin, and selected from the group consisting of polyester resins other than polyarylate, the sublimable dye and the binder resin, in the dye layer, substantially completely dissolved It is characterized by being present.

The present invention also relates to a heat-sensitive sublimation transfer sheet for superimposing the dye layer and the image-receiving sheet and heating the back surface of the substrate sheet with a thermal head to sublimate and transfer the dye to form an image.

Explaining the present invention in detail, the main feature of the present invention is that, when a dye layer ink is prepared using a sublimable dye, which is an essential component constituting the dye layer ink, a binder resin and a solvent, The essential components are selected and used in combination so that the binder resin is kept completely dissolved in the ink solvent.

As the dye characterizing the present invention first, any sublimable dye conventionally used in a heat-sensitive sublimation transfer sheet can be used, but a particularly preferable dye in the present invention is about 150 to 400.
It has a small molecular weight and is selected in consideration of sublimation temperature, hue, light resistance, solubility in ink and binder resin, and the like.

Specifically, for example, those which have been conventionally used as disperse dyes, and preferred ones are Miketone Polyester Yellow YL (manufactured by Mitsui Toatsu, CI Dispers Yellow 42), Miketone Polyester Yellow 5G.
(Mitsui Toatsu, CI Disperse Yellow 5), Kayaset Yellow G (Nippon Kayaku, CI Solvent Yellow 77), Kayaset Yellow A-N (Nippon Kayaku, CI Solvent Yellow 125 (S) )), PTY-52
(Mitsubishi Kasei, CI Disperse Yellow 14-1),
PTY-56 (Mitsubishi Kasei, CI Disperse Yellow 3), Miketone Polyester Red BSF (Mitsui Toatsu, CI Disperse Red 111), Miketone Polyester Red T3B (Mitsui Toatsu, CI Disperse Red 228) (S)), Kayaset Red B (manufactured by Nippon Kayaku, C.
I. Disperse Red 135), Kayaset Red 126 (Nippon Kayaku, CI Disperse Red 4), PTR-54 (C.
I. Disperse Red 50), PTR-63 (Mitsubishi Kasei, C.
I. Disperse Red 60), Miketone Polyester Blue FBL (Mitsui Toatsu, CI Disperse Blue 56),
Discharge Blue R (Mitsui Toatsu, CI Disperse Blue 106), Mitsui PS Blue 3R (Mitsui Toatsu, C.
I. Disperse Blue 33), PTB-67 (manufactured by Mitsubishi Kasei, C.
I. Disperse Blue 241), PTB-77 (manufactured by Mitsubishi Kasei, C.
I. Solvent Blue 90), Kayaset Blue 906 (Nippon Kayaku, CI Solvent Blue 112), Kayaset Blue 141 (Nippon Kayaku, CI Solvent Blue 114 (S))
Etc.

Further suitable other dyes are sublimable basic dyes having sufficient solubility in a solvent, for example, 3,3′-diethyloxathiacyanine iodide, Astrazone Pink FG (manufactured by Bayer, CI48015), 2,2'-carbocyanine (CI808), Astrafiloxin FF (C.
I.48070), Astrazone Yellow 7GLL (CI Basic Yellow 21), Eisen Cachiron Yellow 3GLH (Hodogaya Chemical Co., CI48055), Aizen Cachiron Red 6
BH (CI48020) and other monomethine-based, dimethine- and trimethine-based methine (cyanine) -based basic dyes; Auramine (CI655) and other diphenylmethane-based basic dyes; Malachite Green (CI4200)
0), Brilliant Green (CI42040), Magenta (CI42510), Methyl Violet (CI4253)
5), Crystal Violet (CI42555), Methyl Green (CI684), Victoria Blue B (CI)
Disperse 045) and other triphenylmethane-based basic dyes; Pyronin G (CI739), Rhodamine (CI4517)
0), xanthene-based basic dyes such as rhodamine 6G (CI45160); acridine-based basic dyes such as acridine yellow G (CI785), leonine AL (CI46075), benzoflavin (CI791), and aphine (CI46045); neutral Red (CI50040), Astrazone Blue BGE / × 125% (CI51005), Methylene Blue (CI
52015) and other basic dyes; and other basic dyes such as anthraquinone-based basic dyes having a quaternary amine.

None of these dyes can be used freely, and it is necessary to select and use them in consideration of the relationship between the binder resin, which is another essential component, and the ink solvent.

For example, with respect to the organic solvent selected as the ink solvent, for example, about 0.5 wt% or more for yellow dye, about 1.0 wt% or more for magenta dye, and about 2.0 wt% or more for cyan dye. It should be selected to have solubility.

As the binder resin used in the present invention, any conventionally known binder resin can be used for such purpose, and usually has high heat resistance and does not hinder the migration of the dye when heated. For example, as the cellulose resin, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate butyrate, etc., and as the vinyl resin, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl pyrrolidone, poly Polyester other than arylate, polyacrylamide, etc. are mentioned.

Such a binder resin is preferably selected and used as a binder resin which is substantially completely dissolved in the solvent in relation to the selected ink solvent described later and does not inhibit the solubility of the dye dissolved in the solvent. Is preferred. The amount used is, for example, about 50 parts by weight per 100 parts by weight of the dye.
It is preferably used in an amount of about 1,000 parts by weight so that the concentration of the dye when the dye layer is formed is about 5 to 80% by weight.

As the ink solvent for dissolving the above dye and binder resin in the present invention, conventionally known ink solvents can be freely used, and specifically, as an alcohol solvent, methanol, ethanol, isopropyl alcohol, butanol, isobutanol, etc. , Ketone-based methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.,
Toluene, xylene, etc. as aromatic type, dichloromethane, trichloroethane, etc. as halogen type, dioquinane,
Tetrahydrofuran and the like, and a mixture of the above solvents can be mentioned. It is important to select and use these solvents so that the dye used is at a predetermined concentration or more and the binder resin is sufficiently dissolved.

For example, the total weight of the dye and the binder resin is about 20
It is preferred to use 0 to 5 times the amount of solvent.

The components as described above are essential components in the dye layer ink used in the present invention, and various conventionally known additives can be included in addition to these essential components.

The dye layer ink used in the present invention is a mixture of the above-mentioned essential components and optional components added as necessary, and heated as needed in various mixers to form a sublimable dye and a binder resin. It is obtained by simply dissolving it in a solvent, and does not require the grinding treatment which requires a long time as in the prior art.

The dye layer ink used in the present invention obtained as described above, the components constituting them, particularly the dye and the binder resin are completely dissolved in the ink solvent, and the dissolved state is stably maintained. Since various components are selected and combined as described above, a stable dissolved state is maintained under normal conditions, and even when a dye layer is formed on a substrate sheet using the ink, the dye is The dye and binder resin are selected and combined so that they can be present in solution in the binder resin.

(Operation / Effect) The dye layer ink used in the present invention described above has a dry weight of about 0.2 to 20 g / m ^{2 on} one surface of the base sheet which may be provided with a heat resistant protective layer on the back surface thereof. It is used to form a dye layer by coating within a range, and examples of such a base sheet include condenser paper, polyester film, polystyrene film, polysulfone film, polyimide film, polyvinyl alcohol. Examples include paper or film such as film and cellophane, the thickness of which is 3 to 50 μm,
It is preferably 3 to 15 μm. When price and heat resistance in untreated state are required among these papers and films, condenser paper is used.On the other hand, it has mechanical strength and handling and thermal treatment at the time of making a heat-sensitive sublimation transfer sheet. Polyester flume is preferably used when it is important that it does not break when it is run in the printer and that the surface is smooth.

As described above, since the dye in the dye layer of the heat-sensitive sublimation type transfer sheet obtained by using the dye layer ink used in the present invention is held in a state of being dissolved in the binder resin, it is conventionally known. By overlapping with the image receiving sheet and heating from either side according to the image signal by a heating means such as a thermal head, the dye in the dye layer can be easily transferred to the receiving layer of the image receiving sheet with relatively low energy. It is transferred and transferred in accordance with the size of, and a color image with excellent sharpness and resolution gradation can be formed. When a heat-sensitive sublimation type transfer sheet using the dye layer ink used in the present invention is used, in the case of a heat-sensitive sublimation type transfer sheet similar to the conventional one, the dye in the dye layer is dispersed in a particulate form. Therefore, there are various problems as described above such that the transferability due to the heat of the thermal head is insufficient and non-uniform, and the background stain occurs due to the presence of the dye particles. Has been resolved.

(Example) Next, an example is given and the present invention is explained concretely. still,
In the text, parts are based on weight.

Example 1 An ink for a dye layer used in the present invention was prepared using the following disperse dye, binder resin and solvent.

Disperse dye (PTY-52, made by Mitsubishi Kasei) 0.1 part Ethyl hydroxyethyl cellulose (made by Hercules)
0.45 parts Methyl ethyl ketone toluene (1/1) 9.45 parts The above ink for dye layer is completely transparent, and no precipitates or agglomerates are observed even if stored for 1 month under the temperature condition of 10 ° C. It was

The above dye layer ink was applied to the backside with heat treatment 9μ
A heat-sensitive sublimation transfer sheet was prepared by coating and drying on a m-thick polyester film so that the dry weight was 0.4 g / m ² .

Next, 150 μm thick synthetic paper (made by Oji Yuka, YUP
O-FPG # 150) and a wire bar coating of the ink for the receiving layer with the following composition, and the dry thickness is 4 g / m.
^An image-receiving sheet was prepared by coating so that it would be ² . Drying is done temporarily with a dryer and then in an oven at 100 ° C for 1 hour.
It was carried out by sufficiently evaporating the solvent.

Byron 103 (Toyobo, polyester resin) 8 parts Elvalloy 741 (Mitsui Polychemical, EVA polymer plasticizer) 2 parts Amino-modified silicone oil (Shin-Etsu Silicone, KF-
393) 0.125 parts Epoxy modified silicone oil (Shin-Etsu Silicone, X
-22-343) 0.125 parts Toluene 70 parts Methyl ethyl ketone 10 parts Cyclohexanone 20 parts Heat-sensitive sublimation-type transfer so that the dye layer of the heat-sensitive sublimation transfer sheet obtained as described above and the receptor layer of the image-receiving sheet are in contact with each other. Thermal head output from the support side of the sheet, thermal head output; 1W / 1 dot, pulse width; 0.3-4.5ms
As a result of recording under the conditions of ec, dot density; 3 dots / mm, the transfer density of the high density color development part with a pulse width of 4.5 msec is 1.5
It was 0, and the pulse width of 0.3 msec was 0.26, and recording with gradation according to the applied energy was obtained (measuring instrument;
Macbeth densitometer RD-918).

Example 2 An ink for dye layer was prepared using the following dye, binder resin and solvent.

Disperse dye (KST-B-136, manufactured by Nippon Kayaku) 0.45 part Binder resin (polyvinyl butyral, SLEC-BX-)
1, Shimizu Chemical) 0.45 parts Methyl ethyl ketone / toluene / isobutanol (4.5 /
4.5 / 1.0) 9.10 parts The above dye layer ink was completely transparent and had good stability over time. Example 1 using this dye layer ink
Heat-sensitive sublimation type transfer sheet (dry coating amount 1.0g / m
² ) and an image receiving sheet were prepared and printed in the same manner, and the reflection density was 1.90.

Example 3 An ink for dye layer was prepared using the following dye, binder resin and solvent.

Disperse dye (KST-Red-B, Nippon Kayaku) 0.2 part Binder resin (polyester resin, Vylon200, Toyobo) 0.45 part Methyl ethyl ketone / toluene (1/1) 9.35 parts The above ink for dye layer is completely transparent. And the stability over time was also good. Example 1 using this dye layer ink
When a heat-sensitive sublimation type transfer sheet and an image receiving sheet were prepared in the same manner as above and printed in the same manner, the reflection density was 1.42.

Comparative Example 1 Disperse dye (KST-B-136, manufactured by Nippon Kayaku) 1.0 part Binder resin (ethyl cellulose N / 14, manufactured by Hercules) 3.0 parts Toluene / isopropyl alcohol (8/2) 7.0 parts Mixing the above components, dye The binder resin was not completely dissolved, and the mixture was milled in a ball mill for 24 hours to prepare a dye layer ink for comparison. In the dye layer ink, a part of the dye was dissolved and the other was in a dispersed state. Then, the above-mentioned dye layer ink immediately after preparation and the dye layer ink stored at 10 ° C. for 1 month were each used in Example 1
When a heat-sensitive sublimation transfer sheet was prepared in the same manner as in Example 1 and printing was performed using the image receiving sheet of Example 1 under the same conditions as in Example 1, the dye layer was fused to the receiving layer. The phenomenon occurred, and the print density was 1.45 for the former and 1.35 for the latter, which was not satisfactory. The storage stability of the dye layer ink and the heat-sensitive sublimation transfer sheet using the dye layer ink are also insufficient.

 ─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-51-21033 (JP, A) JP-A-61-41596 (JP, A) JP-A-59-109394 (JP, A) JP-B 47- 44054 (JP, B1) JPB Sho 55-3390 (JP, B2)

Claims (1)

[Claims] 1. A heat-sensitive sublimation transfer sheet for forming an image by a sublimation dye, which is superposed on a heat-sensitive sublimation transfer sheet and heated by a thermal head from the back surface of the base sheet. The heat-sensitive sublimation transfer layer provided on the surface comprises a binder resin and a sublimable dye, and the binder resin is selected from the group consisting of ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose and cellulose acetate butyrate. Cellulose derivative,
Characterized by being selected from the group consisting of vinyl-based resins, polyacrylamide-based resins, or polyester-based resins other than polyarylate, and a sublimable dye being substantially dissolved in the binder in the heat-sensitive sublimation transfer layer. Heat-sensitive sublimation type transfer sheet.