JPH06171241A - Transparent image receiving paper, thermal transfer recording method using the same, thermal transfer recording apparatus and display device - Google Patents

Abstract

PURPOSE:To provide transparent image receiving paper capable of increasing transmission density without greatly increasing a printing time when a monochromatic image is formed on the transparent image receiving paper using a sublimable dye by thermal transfer recording. CONSTITUTION:A transparent base material 2 is a transparent resin film. A transparent thermal layer 3 is formed from a resin having a certain kind of an org. monomeric substance becoming opaque by heating uniformly dispersed therein and continuously changed from a transparent state to an opaque non- transparent state by heating. A transparent dye receiving layer 4 is composed of a resin easily dyed with a sublimable dye. A release layer 5 has function preventing abnormal transfer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent image receiving paper suitable for thermally transferring and recording a monochrome halftone image using a sublimable dye based on an input image from a video device or a computer. is there.

[0002]

2. Description of the Related Art A thermal transfer recording system in which an ink film coated with a sublimable dye is heated by a thermal head to record an image on an image-receiving paper provided with a dye receiving layer is to achieve both high gradation (halftone) and high resolution. It has been adopted for recording the output from various image devices and computers such as video printers, as a method of achieving high quality hard copy comparable to photographs. Further, there is an increasing demand for recording a halftone image on a transparent image receiving paper by such a thermal transfer recording system for an OHP (overhead projector) or a medical imaging device.

Halftone image recording using a transparent image receiving paper expresses image information by the transmittance (transmission density) of transmitted light, and it is desired that the transmission density is about 2.0 at maximum. However, in the image recording on the transparent image receiving paper by the conventional sublimation transfer method, since the dye dyeing amount on the dye receiving layer is insufficient, the transmission density when viewed by transmitted light is low, and the contrast is insufficient. There was a problem that only the insufficient image quality was obtained. This means that even if an equal amount of dye is dyed on the transparent image receiving paper, the transmission density is almost 1 of the reflection density.
This is because the transmission density becomes about 1.0 even if the reflection density is 2.0. Since the maximum reflection density obtained by the current sublimation transfer recording is about 2.5, it is the current situation that a sufficient transmission density cannot be obtained.

[0004]

By the way, as a method for obtaining a high transmission density in sublimation transfer recording on a transparent image receiving paper, conventionally, for example, as disclosed in JP-A-2-587, the same color of an ink film is used. A method of increasing the dyeing amount of the dye by heating with the same image signal by using a plurality of surfaces of (1) and recording the same on the same image receiving paper a plurality of times is used. As other methods, there have been used methods such as heating for a long time in order to completely transfer the dye on the ink film, and a method of reducing the recording line pitch to increase the recording pixel density.

However, all of these methods have a problem that a large increase in printing time is unavoidable and the effect is relatively small.

An object of the present invention is to solve the above-mentioned problems of the prior art, and when a sublimable dye is used to thermally transfer record a monochrome image on a transparent image-receiving paper, the transmission density is increased without significantly increasing the printing time. An object of the present invention is to provide a transparent image receiving paper which can increase the height.

[0007]

In order to achieve the above-mentioned object, in the present invention, a transparent image-receiving paper is formed on a film-like transparent base material and the transparent base material, and the transparent image-receiving paper is removed from the transparent state by heating. It was composed of a heat-sensitive layer which continuously changes into a cloudy and non-transparent state, and a transparent dye-receiving layer which is formed on the heat-sensitive layer and which transfers and dyes a sublimable dye.

[0008]

The transparent image-receiving paper having the above-mentioned structure is used, and this and a monochrome ink film containing a sublimable dye are superposed and heated by a thermal head. With this, the dye is transferred to the dye receiving layer, and at the same time, the heat-sensitive layer becomes cloudy, and the transmission density corresponding to the input signal on the transparent image receiving paper is obtained by adding the transmission density due to dye dyeing and the transmission density due to clouding. It is for forming a monochrome halftone image that it has.

That is, in the transparent image-receiving paper of the present invention, the heat-sensitive layer becomes cloudy by heating and changes to have a monochrome transmission density with respect to transmitted light. In addition to this, the transmission density can be increased by the density of the heat-sensitive layer. Further, by making the cloudiness amount of the heat-sensitive layer, that is, the transmission density characteristic with respect to the heating energy, to have the same tendency as the transmission density characteristic by the transfer dyeing of the sublimable dye, the transmission density to the high density portion of the image is increased. It is possible to obtain high image quality with good contrast.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a section of a transparent image receiving paper as a first embodiment of the present invention.

In FIG. 1, reference numeral 1 is a transparent image receiving paper having a transparent heat sensitive layer 3 and a transparent dye receiving layer 4 formed on a transparent substrate 2. The base material 2 in FIG. 1 is a transparent resin film of polyethylene terephthalate, polycarbonate, acrylic or the like. The heat-sensitive layer 3 is formed by uniformly dispersing, in a resin, a certain organic low molecule that becomes cloudy when heated. A resin having a high transparency is desirable as the resin, and examples thereof include polyvinyl chloride, polyvinyl chloride-polyvinyl acetate copolymer, polyvinyl chloride, polyester, polyamide, and acrylic. On the other hand, as the organic low molecule, higher alcohol, higher fatty acid or the like can be used. Also, sulfide if necessary _{[HOOC- (CH 2) m -S- (} CH 2) n
An appropriate amount of additive such as —COOH] may be mixed.

The dye receiving layer 4 is not particularly limited as long as it is a resin which is easily dyed with a sublimable dye, and any of those conventionally used can be used. For example, polyester resin, polyurethane resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer resin, etc. can be used. Of course, additives such as various plasticizers, antioxidants, and ultraviolet absorbers may be mixed in these.

If desired, a peeling layer 5 may be provided on the dye receiving layer 4 to prevent abnormal transfer. Release layer 5
As the material, for example, an ultraviolet curable silicone resin, a thermosetting silicone resin, a fluorine-containing resin or the like formed on the dye receiving layer 4 by about 0.05 to 0.1 μm can be used. Alternatively, various modified silicone oils may be added to the dye receiving layer 4,
You may use the method of mixing fluorine oil, wax, various surfactants, etc.

FIG. 2 is a sectional view showing a section of a transparent image receiving paper as a second embodiment of the present invention.

In FIG. 2, the same components as those in FIG. 1 are designated by the same reference numerals. The transparent image receiving paper 1 shown in FIG. 2 has an intermediate layer 6 provided between the heat-sensitive layer 3 and the dye receiving layer 4 of the transparent image receiving paper 1 shown in FIG. The material of the intermediate layer 6 is preferably a thermoplastic resin, for example, polyester, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polypropylene, polyethylene, polystyrene, polystyrene ionomer, polyethylene ionomer, etc. are applied. Examples thereof include those obtained by laminating these films with heat or an adhesive.

The purpose of providing the intermediate layer 6 is to appropriately control the amount of heat transfer to the heat-sensitive layer 3 or to delay the heat transfer appropriately to control the opaque characteristics and to serve as an image receiving paper. For example, by increasing the cushioning property, the concentration can be increased.

Among them, the former will be explained. By providing the intermediate layer 6, it is possible to control the characteristics of the heat sensitive layer 3 which becomes cloudy with respect to the heating energy. A monotonically increasing characteristic having almost the same tendency as the concentration characteristic can be obtained. As a result, the total transmission density characteristics, including the density due to dye dyeing, are increased with increasing heating energy.
Compared with the conventional transparent image receiving paper, the density can be gradually increased over the entire density range, and gradation characteristics can be obtained smoothly and the maximum transmission density characteristics can be obtained.

The latter will be described. The intermediate layer 6
Has the effect of increasing the cushioning property of the image receiving paper. That is, in general, a transparent image-receiving paper such as an OHP film has a small cushioning property when the thermal head is pressed due to the nature of the material of the transparent substrate, and the transfer ink of the dye ink is smaller than the size of the heating element of the thermal head. There is a strong tendency for the recording dot shape to become smaller due to wear. For this reason, there is a problem that white stripes are generated between dots and the transmission density is lowered. Since the transparent image-receiving paper according to the present invention has one more heat-sensitive layer 3, it can provide cushioning properties as compared with the conventional image-receiving paper, but the provision of the intermediate layer 6 can further increase the cushioning property of the image-receiving paper. . As a result, the contact area between the ink paper and the image receiving paper when pressed by the thermal head at the time of recording is increased, and the dyeing area of the dye is increased, so that there is no non-coloring part between dots, and the effect of increasing the transmission density can be expected. .

Next, FIG. 3 is a side view showing a main part of a thermal transfer recording apparatus for performing thermal transfer recording using the transparent image receiving paper shown in FIGS. Basically, it is no different from the conventional thermal transfer recording apparatus using the sublimation transfer recording method.

In FIG. 3, reference numeral 1 denotes the above-mentioned transparent image-receiving paper, which comprises a transparent substrate 2, a transparent heat-sensitive layer 3 and a transparent dye-receiving layer 4. As described above, the intermediate layer 6 may be provided between the heat sensitive layer 3 and the dye receiving layer 4, and the dye receiving layer 4
A peeling layer 5 may be provided on the above. 7 is an ink film in which a dye layer 8 containing a monochrome sublimable dye is applied on a base film 9; 10 is an ink film supply reel;
1 is the same take-up reel. Reference numeral 12 is a platen, 13 is a thermal head having a plurality of heating elements, and 14 is a heating element of the thermal head.

During recording, the ink film 7 and the transparent image receiving paper 1 are conveyed in the arrow direction at the same speed in synchronization with the rotation of the platen 12. This thermal transfer recording apparatus is similar to a thermal transfer recording apparatus based on a conventional sublimation transfer recording method in a state where the dye layer 8 side of the ink film 7 and the dye receiving layer 4 side of the transparent image receiving paper 1 are in close contact with each other. The heating is performed by heating the material 9 side by the heating element 14 of the thermal head 13 with energizing energy according to the density of the recorded image. As a result, a predetermined amount of the dye ink is transferred to the dye receiving layer 4 of the transparent image receiving paper 1 according to the amount of heating energy of each heating element 14 to form a recording dot, and at the same time, the heat sensitive layer at a position corresponding to the dot. 3 becomes cloudy by a predetermined amount, and pixels having a predetermined transmission density are recorded as a total. At this time, needless to say, the energization energy to the thermal head 13 is controlled in advance in consideration of the increase in the transmission density due to the cloudiness. Ink film 7,
Recording is continued while the transparent image receiving paper 1 is being conveyed, and monochrome image recording on one surface is performed on the transparent image receiving paper 1.

Next, FIG. 4 is a characteristic diagram showing an example of transmission density characteristics when monochrome halftone image recording is performed using the transparent image receiving paper shown in FIGS.

In FIG. 4, (A) is a transmission density characteristic of dye transfer dyeing with respect to heating energy when sublimation transfer recording is performed using the transparent image receiving paper of the present invention, that is, only dyeing of the dye receiving layer 4 is performed. This is the transmission density characteristic.

(B) is the opaque characteristic of the transparent image-receiving paper of the present invention provided with the heat-sensitive layer 3 from the transparent state to the non-transparent state, that is, the transmission density characteristic of the heat-sensitive layer 3 with respect to heating energy. The characteristic (B) is obtained by heating the transparent image-receiving paper of the present invention in the same manner as in ordinary printing using an ink film base material not coated with a dye, and measuring the transmission density of the resulting cloudy film. Although the transmission density due to clouding and non-transparency is lower than the transmission density due to dyeing, it shows a monotonically increasing characteristic that is almost the same as the concentration characteristic of the dye with respect to heating energy. It should be noted that the transmission density characteristic due to white turbidity shown in (B) is a characteristic obtained when light that is close to parallel light, such as that emitted from a light source in an OHP, is transmitted, and is observed when transmitting with non-directional scattered light. , The cloudiness concentration decreases due to light scattering.

Further, the transmission density by thermal transfer recording when the transparent image-receiving paper of the present invention is used is expressed as the sum of the respective densities as a superposition of (A) and (B), and therefore, as shown in (C). Become. The increase of the density is remarkable in the high density region. In the example shown in FIG. 4, the maximum density of (A) is about 1.5 and the maximum density of (B) is about 0.5. About 2.0
Has been obtained.

The transparent image-receiving paper of the present invention has a higher transmission density (A) only by dyeing the dye-receiving layer 4 than that of the conventional transparent image-receiving paper, and the maximum density is 0.1 as compared with the conventional one.
~ 0.2 higher, reaching about 1.5. It is considered that this is because the cushioning property is increased as compared with the conventional image receiving paper, and the dyed area of the receiving layer per dot is increased. Next, FIG. 5 is a side view showing a main part of an overhead projector using the transparent image receiving paper shown in FIGS. 1 and 2 on which thermal transfer recording has been performed.

In FIG. 5, 15 is a light source, 16 is a stage made of a transparent plate, 17 is a lens, and 18 is a mirror.

In this OHP, the transparent image receiving paper 1 shown in FIGS. 1 and 2 is used, and the transparent image receiving paper 1 on which an image has been formed by the thermal transfer recording by the thermal transfer recording apparatus shown in FIG. As shown in FIG. 5, it is placed on the stage 16 to transmit the light emitted from the light source 15, and the transmitted light is reflected by a mirror 18 and irradiated on a screen (not shown) to project an image in an enlarged manner.

As described above, the light source 15 in the OHP
Since the light emitted from the near-parallel light is similar to the parallel light, the transparent image-receiving paper of the present invention on which thermal transfer recording has been carried out is OH as shown in FIG.
When it is used for P, the transmission density due to the cloudiness of the heat sensitive layer 3 can be further increased. As a result, a high-quality projected image with high density and high contrast can be obtained, and a large presentation effect can be obtained.

Finally, specific examples of the transparent image receiving paper shown in FIGS. 1 and 2 will be described. However, the composition is not limited to this.

Specific Example 1 Specific example 1 is a specific example of the transparent image receiving paper shown in FIG.

First, the base material 2 of the transparent image-receiving paper 1 was a polyethylene terephthalate film having a thickness of 180 μm, and the heat-sensitive layer 3 having the composition shown in Table 1 was applied to one surface of the polyethylene terephthalate film so that the coating thickness was 5 μm.

[0034]

[Table 1]

Next, a polyester resin layer having a thickness of 37 μm was laminated on the heat-sensitive layer 3 as a dye receiving layer 4 for receiving and dyeing a sublimable dye by lamination.

Further, the composition shown in Table 2 was applied as an abnormal transfer prevention layer thereon, dried, and cured by UV to obtain a transparent image receiving paper 1.

[0037]

[Table 2]

The transparent image-receiving paper 1 thus obtained was used to perform thermal transfer recording with a monochrome sublimable dye ink film, and as a result, the maximum transmission density could be increased by 0.4 or more as compared with the prior art.

SPECIFIC EXAMPLE 2 Specific example 2 is a specific example of the transparent image receiving paper shown in FIG.

In Example 1, a 12 μm-thick polyethylene terephthalate film having an acrylic pressure-sensitive adhesive layer having a thickness of 15 μm was used as the intermediate layer 6 between the heat-sensitive layer 3 and the dye receiving layer 4, and the pressure-sensitive adhesive layer was placed on the heat-sensitive layer side. A transparent image-receiving paper was obtained in the same manner as in Example 1 except that the dye-receiving layer 4 had a thickness of 6 μm.

The transparent image-receiving paper thus obtained was used to perform thermal transfer recording with a monochrome sublimable dye ink film. As a result, as shown in FIG. 4B, the cloudiness density characteristic having the same tendency as the dye density characteristic was obtained. To obtain the total transmission density characteristic as shown in FIG. As a result, the transmission density can be increased particularly in the high density region, and a high-quality printed image with high contrast can be obtained.

[0042]

As described above, according to the transparent image-receiving paper of the present invention, the heat-sensitive layer becomes turbid due to heating and changes to have monochrome transmission density for transmitted light.
In addition to the density of the sublimation dye by transfer dyeing, the transmission density can be increased by the density of the heat-sensitive layer. Therefore, there is an effect that the transmission density can be increased without significantly increasing the printing time.

Further, since the white turbidity characteristic of the heat sensitive layer with respect to the heating energy can be made to have the same tendency as the transmission density characteristic by the transfer dyeing of the sublimable dye, the transmission density in the high density portion of the image can be increased. It is possible to obtain high image quality with high contrast.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a cross section of a transparent image receiving paper as a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a cross section of a transparent image receiving paper as a second embodiment of the present invention.

FIG. 3 is a side view showing a main part of a thermal transfer recording apparatus for performing thermal transfer recording using the transparent image receiving paper shown in FIGS.

FIG. 4 is a characteristic diagram showing an example of transmission density characteristics when monochrome halftone image recording is performed using the transparent image receiving paper shown in FIGS.

FIG. 5 is a side view showing a main part of an overhead projector using the transparent image receiving paper shown in FIGS. 1 and 2 on which thermal transfer recording has been performed.

[Explanation of symbols]

1 ... Transparent image receiving paper, 2 ... Transparent substrate, 3 ... Transparent heat sensitive layer, 4 ...
Transparent dye receiving layer, 6 ... Intermediate layer, 7 ... Ink film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichiro Ito 1-1-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Inventor Shigeru Katayama 1-1-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (7)

[Claims] 1. A film-like transparent substrate, a heat-sensitive layer formed on the substrate and continuously changing from a transparent state to a cloudy non-transparent state by heating, and formed on the heat-sensitive layer. And a transparent dye receiving layer that transfers and dyes a sublimable dye,
A transparent image-receiving paper characterized by being composed of. 2. The transparent image receiving paper according to claim 1, wherein:
The characteristic of the transmission density of the heat-sensitive layer with respect to the change of heating energy has the same tendency as the characteristic of the transmission density of the dye receiving layer on which the sublimable dye is transfer dyed, with respect to the change of heating energy. Transparent image receiving paper. 3. The transparent image receiving paper according to claim 1, wherein:
A transparent image-receiving paper, characterized in that an intermediate layer is provided between the heat-sensitive layer and the dye-receiving layer to control the amount of heat transferred to the heat-sensitive layer or delay the transfer of heat. 4. The transparent image receiving paper according to claim 2,
The intermediate layer has the same characteristics of the transmission density of the heat-sensitive layer with respect to the change of heating energy, and has the same tendency as the characteristics of the transmission density of the dye receiving layer on which the sublimable dye is transfer dyed, with respect to the change of heating energy. Therefore, the transparent image receiving paper is characterized in that the amount of heat transfer to the heat sensitive layer is controlled or the heat transfer is delayed. 5. An ink paper comprising the transparent image-receiving paper according to claim 1, 2, 3 or 4 and a dye layer containing the sublimable dye formed on a substrate, wherein the transparent image-receiving paper contains a dye. In a state where the receiving layer and the dye layer of the ink paper are overlapped so as to face each other, from the base material side of the ink paper, a thermal head is heated according to an input signal, and the transparent image receiving paper receives the input signal. A thermal transfer recording method comprising forming an image having a corresponding transmission density. 6. An ink paper comprising a means for transporting the transparent image receiving paper according to claim 1, 2, 3 or 4 in one direction and a dye layer containing the sublimable dye formed on a substrate. A means for moving the transparent image receiving paper in the same direction as the conveying direction of the transparent image receiving paper, and pressing the ink paper from the base material side so that the dye receiving layer of the transparent image receiving paper and the dye layer of the ink paper face each other. The thermal transfer recording apparatus, further comprising: a thermal head that superimposes the ink paper on the transparent image receiving paper and heats the ink paper from the base material side in accordance with an input signal. 7. A means for holding a transparent image receiving paper on which an image is formed, a light source for generating light close to parallel light and irradiating the transparent image receiving paper, and a transmitted light transmitted through the transparent image receiving paper on a screen. An optical system that illuminates and projects the image in an enlarged scale;
7. A display device comprising: the transparent image receiving sheet according to claim 1, 2, 3 or 4, wherein the transparent image receiving sheet has an image formed by the thermal transfer recording method according to claim 5. A display device characterized by using.