JPH0364317B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to dye-donor elements used in thermal transfer dyeing, and more particularly to the use of dye-barrier layers and subbing layers to improve dye transfer density. In recent years, thermal transfer systems have been developed to obtain prints from images obtained electronically from color video cameras. According to one method of obtaining such prints, the electronic image is first color separated with color filters. Each color-separated image is then converted into an electrical signal. These signals are then manipulated into cyan, magenta and yellow electrical signals. These signals are then sent to a thermal printer. To obtain a print, a cyan, magenta or yellow dye-donor member is placed face-to-face with a dye-receiver member. These two are then placed between the thermal print head and the platen roller. Heat is applied from the back of the dye-donor sheet using a line type thermal print head. The thermal print head has a number of heating elements and is heated in response to sequential cyan, magenta and yellow signals. This process is then repeated for the other two colors. A color hard copy corresponding to the original image seen on the screen is thus obtained. Details of a process and apparatus for accomplishing this are provided in Brownstein, US Pat. Japanese Patent Publication No. 19138/85 describes an image-receiving member for thermal transfer printing. Example 3 of this publication also describes a dye-donor element, which shows a 2 g/m ² gelatin subbing layer between the dye layer and the support. European Patent Application No. 109295 states that “priming” such as polycarbonate or
There is a description of a dye-donor sheet having . These basecoats are said to be hydrophobic and melt when the sheet is heated. Most dyes used in thermal printing are hydrophobic, so
They tend to diffuse into such layers, so less dye is available for transfer. Dye layers for thermal transfer printing that are coated directly onto the support for the donor element, such as poly(ethylene terephthalate), contain dyes with uncontrolled directional movement into the support during the transfer process. There is a problem of loss due to non-diffusion. Dye-
The donor support has the inherent property of softening during heating and acting as a receiver for the dye. This undesirable loss of dye by diffusion results in less dye being transferred to the dye-receiving member. Since the background concentration in thermal transfer dyeing systems is essentially constant, any increase in the concentration of transferred dye within the image area will improve discrimination, which is highly desirable. It is an object of the present invention to provide a method for increasing the concentration of transferred dye in a dye-donor element for thermal transfer dyeing, and also to provide good adhesion between the dye-barrier layer and the support. It is. These and other objects require that a hydrophilic dye-barrier layer be used in a dye-donor element for thermal transfer dyeing consisting of a support having a dye layer on one side and a slipping layer of a lubricating substance on the other side. achieved by the invention, comprising a dye-donor element for thermal transfer dyeing as described above, between the dye layer and the support, and the subbing layer between the dye-barrier layer and the support. . In a preferred embodiment of the invention, the dye-barrier layer is present from 0.1 to 1.6 g/m ² . The hydrophilic dye-barrier layer may contain any hydrophilic material useful for the intended purpose.
In general, excellent results have been obtained using gelatin, poly(isopropylacrylamide), butyl methacrylate grafted gelatin, ethyl acrylate grafted gelatin, ethyl methacrylate grafted gelatin, cellulose monoacetate, methylcellulose, poly(vinyl alcohol), poly(ethyleneimine), Obtained with a mixture of poly(vinyl alcohol) and poly(vinyl acetate), a mixture of poly(vinyl alcohol) and poly(acrylic acid) or a mixture of cellulose monoacetate and poly(acrylic acid). Particularly preferred embodiments of the invention use cellulose monoacetate or poly(vinyl alcohol). Any primer material that performs the desired function may be used in the present invention. In a preferred embodiment, excellent results are obtained using a (acrylonitrile-vinylidene chloride acrylic acid) copolymer (weight ratio 14:
80:6), (butyl acrylate-methacrylic acid 2-
aminoethyl-2-hydroxyethyl methacrylate) copolymers (30:20:50 weight ratio), linear/saturated polyesters such as Vosteik 7650 (Emhart, Vosteik Chemical Group) or chlorinated high-density poly(ethylene-trichloroethylene) Obtained with resin. The subbing layer may be applied in any amount effective for the desired effect. In general, excellent results were obtained in the range 0.01 to 2.0 g/m ² . Any dye that can be transferred to the dye-receiving layer by the action of heat can be used in the dye layer of the dye-donor element of this invention. Particularly good results were obtained with sublimable dyes such as: or any of the dyes described in U.S. Pat. No. 4,541,830. The above dyes can be used alone or in combination to obtain a single color. Dye is 0.05-1g/ ^m2
It can be used within the range of 100%, and preferably hydrophobic. The dye in the dye-donor member is a polymeric binder such as a cellulose derivative such as cellulose acetate hydrogen phthalate, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose triacetate; polycarbonate; (styrene-acrylonitrile) copolymer, poly(sulfone). ) or poly(phenylene oxide). The binder can be used in a range of 0.1 to 5 g/ ^m2 . The dye layer of the dye-donor member may be coated onto the support or printed thereon by printing techniques such as gravure. Any material that is dimensionally stable and capable of withstanding the heat of a thermal print head can be used as a support for the dye-donor element of this invention. Such materials include polyesters such as poly(ethylene terephthalate); polyamides; polycarbonates; glassine paper; capacitor paper; cellulose esters; fluoropolymers; polyethers; polyolefins; and polyimides. The support generally has a thickness of 2
~30μm. The back side of the dye-donor member is coated with a slipping layer that prevents the print head from sticking to the dye-donor member. Such slipping layers consist of lubricating substances, such as surfactants, liquid lubricants, solid lubricants or mixtures thereof, with or without polymeric binders. Dye-receiving members for use with the dye-donor members of this invention typically consist of a support having a dye image-receiving layer thereon. For example, the support may be a transparent film, such as poly(ethylene terephthalate), or it may also be reflective, such as a barrier paper or white polyester (white pigmented polyester). Dye image-receiving layers may be made of, for example, polycarbonate, polyurethane, polyester, polyvinyl chloride, (styrene-acrylonitrile) copolymer,
Consists of poly(caprolactone) or mixtures thereof. As noted above, the dye-donor members of the present invention are used to form transferred images. Such methods consist of an imaging process in which a dye-donor member as described above is heated and a dye image is transferred to a dye-receiver member to form a transferred image. The dye-donor elements of this invention may be used in sheet form or in continuous roll or ribbon form.
If a continuous roll or ribbon is used, it has only one dye on it or, as described in U.S. Pat. No. 4,541,830,
It has alternating regions of different dyes, such as sublimable cyan, magenta, yellow, black, etc. Accordingly, one, two, three or four colored members (or even more) are within the scope of the present invention. In a preferred embodiment of the invention, the dye-donor member consists of a poly(ethylene terephthalate) support coated with sequentially repeating regions of cyan, magenta and yellow dye, and the above process steps are applied to each color. A three-color transfer image is obtained. Of course, when this process is performed only for a single color, a single color transfer image is obtained. Thermal print heads that can be used to transfer dyes from the dye-donor elements of this invention are commercially available. For example, Fujitsu thermal head (FTP-
040MCS001), TDK thermal head F415HH7−
1089 or Rohm thermal head KE2008-F3 can be used. The thermal transfer dyeing combination for use in the present invention comprises (a) a dye-donor member as described above and (b) a dye-receiver member as described above, wherein the dye layer of the dye-donor member is a dye-donor member as described above. a dye-image-receiving layer in contact with the dye-image receiving layer of the receiving member;
The receiver member is in overlapping relationship with the dye-donor member. The above-mentioned combination of these two members may be pre-combined as an integral unit when a monochromatic image is to be obtained.
This can be done by temporarily gluing the two parts together at their ends. After the metastasis,
Peeling off the dye-receiving member reveals the transferred image. When a three-color image is to be obtained, the above combination is formed in three cases while heat is applied by the thermal print head. After transferring the first dye, the member is peeled off. A second dye-donor member (or another area of the donor member with a different dye area) is then properly aligned with the dye-receiver member and the process is repeated. The third color is obtained in the same way. EXAMPLES The following examples are presented to illustrate the invention. Example 1 A dye-donor member was prepared with the following layers in the order listed:
Prepared by coating on a 6 μm poly(ethylene terephthalate) support: (1) subbing layer of (acrylonitrile-vinylidene chloride-acrylic acid) copolymer (weight ratio 14:80:6); (2) table (3) a dye layer containing the following magenta dye in the specified binder: The backing of each dye-donor member consists of (a) a binder of cellulose acetate butyrate (14% acetyl, 37% butyryl);
(0.54g/m ² ) in beeswax (0.54g/m ² ) or
(b) Coated with either a slipping layer of poly(vinyl stearate) (0.30 g/m ² ) in a binder of (vinyl alcohol-butyral) copolymer (0.45 g/m ² ). For control member 1 and inventive members A and B, the dye layer was 0.15 g/m ² of magenta dye coated from tetrahydrofuran, 0.15 g/m ² of magenta dye coated from tetrahydrofuran.
-ethyl-2-hydroxymethyl-1,3-propanediol and 0.54 g/ ^m2 high viscosity cellulose acetate. For control members 2 and 4-7 and inventive members C, D and FW, the dye layer was 2-
8% cyclohexanone and 11% in butanone
of acetone and 0.39 g/m ² of cellulose acetate hydrogen phthalate (18-21% acetyl, 32-36% phthalyl) ^. Regarding control member 3 and member E of the present invention,
The dye layer was coated from 8% cyclohexanone and 11% acetone in 2-butanone.
m ² of magenta dye and 0.54 g/m ² of high viscosity cellulose acetate. For control donor members 1 and 3, and inventive members A, B and E, the dye-receiving member was made from 4.8 g/m ² Ularac P-2504 (GCA Chemical Co.) hydroxylated branched polyester resin. It consisted of a reflective paper support with a waterproof poly(ethylene)-titanium dioxide overcoat coated with a dye image-receiving layer. 2.9 g/m ² for all other donor members
Macrolon 5705 (Bayer) polycarbonate resin was coated onto an ICI Melinex 990 white polyester support from a dichloromethane and trichloroethylene solvent mixture. The dye side of a 0.75 inch (19 mm) wide dye-donor member slip was placed in contact with the dye image-receiving layer of the same width dye-receiver member. This combination was secured to the jaw of a stepper motor-driven tensioner. Place the assembly on a 0.55 inch (14 mm) diameter rubber roller and press a Fujitsu thermal head with a spring force of 3.5 pounds (1.6 Kg) onto the dye-donor member side of the assembly and press it onto the rubber roller. pressed against. The imaging electronics were activated and the tensioner pulled the printhead/roller combination at 0.123 inches/second (3.1 mm/second). At the same time, the resistor inside the thermal print head
Heating from 0 to 4.5msec in 0.5msec increments,
A scale density test pattern was obtained. The voltage supplied to the print head was approximately 19V, which was approximately 1.75 Watts/
It meant dot. Estimated head temperature is 250-400℃
It was hot. separating the combination and discarding the dye-donor member;
Dye transferred to the dye-receiver member was measured on an X-Lite 338 color reflectance densitometer with a Status A filter. The following results were obtained:

【table】

TABLE These results demonstrate that the dye-barrier layer of the present invention is effective in significantly increasing maximum density compared to the control without dye-barrier layer. Example 2 Various Dye-Barrier Layers (A) Dye-donor elements according to the invention were prepared by coating the following layers on a 6 μm poly(ethylene terephthalate) support in the order listed: 1) Butanone and cyclopentanone (95:
5) subbing layer of (acrylonitrile-vinylidene chloride-acrylic acid) copolymer (weight ratio 14:80:6) at 0.11 g/ ^m2 or 0.43 g/ ^m2 , coated from a solvent mixture; (2) coated from water; a dye-barrier layer (0.16 g/m ² ) as shown in Table 2, and (3) cellulose acetate propionate binder (2.5% acetyl, 45% propionyl) coated from a toluene and methanol (80:20) solvent mixture. Dye layer containing the following magenta dye (0.17g/m ² ) in (0.34g/m ² ): On the back of the part, a (styrene-acrylonitrile) copolymer (70:30 by weight) coated from a solvent mixture of tetrahydrofuran and cyclopentanone (90:10) complex phosphoric acid mono- and diester non-ionic in a binder (0.58 g/m ² ) Surfactant (0.032g/m ² ), Gafatsuku RA600
(GAF), was coated with a slipping layer. (B) A control member was prepared as in (A) except without the dye-barrier or subbing layer. (C) Another control member was prepared as in (A) except that it had a subbing layer but no barrier layer. The dye-receiving member was coated with a solution of Macrolon 5707 (Bayer) polycarbonate resin (2.9 g/m ² ) and release agent FC-431 (3M) (40 mg/m ² ) onto an ICI Melinex 990 white polyester support. Prepared by coating from a methylene and trichloroethylene solvent mixture. The dye side of a 1 inch (25 mm) wide dye-donor member strip was placed in contact with the dye image-receiving layer of the same width dye-receiver member. This assembly was secured to the jaw of a stepper motor-driven tensioner. Diameter of the combined body is 0.55 inch (14 mm)
and press a TDK thermal head L-133 (No. C6-0242) against the dye-donor member side of the combination with a spring force of 8 pounds (3.6 kg). I pressed it against the rubber roller. The imaging electronics were activated and the tensioner pulled the printhead and roller combination at 0.123 inches/second (3.1 mm/second). At the same time, the resistor in the thermal print head was pulse heated for about 8 msec to create the highest density image. The voltage supplied to the print head is approximately 22V.
, which meant approximately 1.5 watts/dot (12 millijoules/dot) for maximum power. The dye-acceptor was separated from each dye-donor and the Green Status A reflection peak density was read. Each dye-donor member was also subjected to tape adhesion testing. Small area (approximately 1/2 inch x 2 inches)
A piece of 3M Highland 6200 permanent mending tape was pressed firmly by hand onto the top dye layer of the dye-donor member, leaving enough area intact to act as a handle when pulling the tape apart. . When the tape was pulled apart by hand, none of the dye layers with adjacent barrier layers came off under ideal conditions. When the dye layer peeled off, this indicated a weak bond between the support and the coating layer. An effective subbing layer always had stronger bonds between the other layers, thus preventing such dye layers from being stripped to the tape. Classified as follows: E-Excellent (no dye layer peeling off) G-Excellent (negligible amount and area of dye layer peeling off) F-Good (small amount and small area of dye layer peeling off) P-Poor ( (A considerable area of the dye layer peels off) U-Fail (The dye layer peels off completely) The following results were obtained:

【table】

Table: *No subbing layer The above results show that the transfer is acceptable without the use of a dye-barrier layer or a subbing layer, but the adhesion is unsatisfactory. Adhesion is satisfactory if only the undercoat layer is used, but
The transferred dye concentration decreases. The combination of the two, a dye-barrier layer and a subbing layer, minimizes both problems. Example 3 Various subbing layers Dye-receiving members were prepared as in Example 2. Dye-donor elements according to the invention were prepared by coating the following layers on a 6 μm poly(ethylene terephthalate) support in the order listed: (1) either 0.11 or 0.43 g/m ² (2) the subbing layer shown in Table 3, coated from a butanone and cyclopentanone (95:5) solvent mixture; (2) poly(vinyl alcohol) coated from water;
(0.16 g/m ² ) dye-barrier layer, and (3) dye layer as in Example 2. A slipping layer was also coated on the back of the member as in Example 2. The following undercoat layer materials were used: (A) (acrylonitrile-vinylidene chloride-acrylic acid) copolymer (weight ratio 14:80:6) (B) (butyl acrylate-2-aminoethyl methacrylate-2-aminoethyl methacrylate) Hydroxyethyl) (weight ratio 30:20:50) (C) Vosteik 7650 linear saturated polyester (Mhart, Vosteik Chemical
group) and (D) chlorinated high-density poly(ethylene-trichloroethylene) resin. A control dye-donor or as shown in Table 3 was prepared without a barrier layer and without a subbing layer. The resistor in the thermal print head is heated from 0 to 8.3 msec.
The dye-
A donor and dye-acceptor were used. The dye-acceptor was manually separated from each dye-donor. Dye-
Separation was considered excellent (E) if the donor did not stick to the dye-acceptor. Dye - Part of the donor is a dye -
Separation was considered unsuccessful if it stuck to the receptor (U). Also read the status A green reflection density,
The effectiveness of the barrier layer was measured. The following results were obtained:

【table】

TABLE The above results demonstrate that the maximum transfer density was improved by the inclusion of a poly(vinyl alcohol) barrier layer. Without the subbing layer, adhesion was unsatisfactory. By including either type of subbing layer along with the barrier layer, both excellent transfer density and adhesion were obtained. The improvement in transfer density was further increased as the amount of basecoat material was increased. Example 4 Various amounts of subbing layers Dye-receiving members were prepared as in Example 2. The dye-donor member of the present invention was coated with 6 μm poly(ethylene terephthalate) in the following layers in the order listed:
Prepared by coating onto a support: (1) Butanone and cyclopentanone (95:5)
Coating (acrylonitrile-vinylidene chloride-acrylic acid) copolymer from solvent mixture (weight ratio
14:80:6) subbing layer; (2) a dye-barrier layer of poly(vinyl alcohol) at the concentrations specified in Table 4 coated from water;
and (3) a dye layer as in Example 2. A slipping layer was also applied to the back of the part as in Example 2. The same evaluation method as in Example 2 was used. The following results were obtained:

Table: None The above results show that although a small amount of poly(vinyl alcohol) of 0.1 g/m ² acts as a barrier layer, the transferred dye concentration was most improved at higher concentrations. There were no adhesion problems with the coating in this experiment. Since most dyes used in thermal transfer printing are hydrophobic and have negligible affinity for or solubility in hydrophilic materials, hydrophilic materials are preferred as dye-barrier layers. It can work. The barrier layer thus acts to prevent undesirable transfer of dye to the dye-donor support, thereby increasing the concentration of transferred dye. The subbing layer ensures good adhesion between the dye-barrier layer and the support.

Claims (1)

Claims: 1. A dye-donor member for thermal transfer dyeing comprising a support having a dye layer on one side and a slipping layer of a lubricating substance on the other side, wherein the hydrophilic dye-barrier layer is as described above. a subbing layer is between the dye layer and the support, a subbing layer is between the dye-barrier layer and the support, and the hydrophilic-barrier layer is made of polyisopropylacrylamide, cellulose monoacetate, methyl cellulose, polyvinyl alcohol. , polyethyleneimine, a mixture of polyvinyl alcohol and polyvinyl acetate, a mixture of polyvinyl alcohol and polyacrylic acid, or a mixture of cellulose monoacetate and polyacrylic acid, and the undercoat layer is a copolymer of acrylonitrile-vinylidene chloride-acrylic acid. The above heat transfer method is characterized in that it is composed of a butyl acrylate-2-aminoethyl methacrylate-2-hydroxyethyl methacrylate copolymer, a linear saturated polyester or a chlorine high density poly(ethylene-trichloroethylene) resin. Dye-donor agent for dyeing.