JPH032093A - Image receiving paper for thermal transfer recording - Google Patents

Abstract

PURPOSE:To eliminate dot missings and to enhance surface gloss by forming image receiving paper for thermal transfer recording by providing an image receiving layer having surface Bekk smoothness of 2,500 sec or more and center surface average roughness of 0.1mum or more on the base material of the image receiving paper. CONSTITUTION:An image receiving layer composition composed of an ultraviolet curable resin to which a photopolymerization initiator, a diluent or the like are added is applied to a base material 1 by a gravure coater or a knife coater and subsequently cured by the irradiation with ultraviolet rays to obtain image receiving paper 10 for thermal transfer recording having an image receiving layer 2 with surface Bekk smoothness of 2,500 sec or more and center surface average roughness of 0.1mum or less formed thereto. When this image receiving paper for thermal transfer recording is used as the recording paper of a sublima tion type thermal transfer recording apparatus, a sharp recording image of high quality can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image receiving paper for thermal transfer recording, and in particular, an image receiving paper for thermal transfer recording with a silver halide photographic tone that provides a high quality recorded image and has a high surface gloss. (hereinafter also simply referred to as "image receiving paper").

[Conventional technology]

2. Description of the Related Art In recent years, various color image reproducing devices such as home video and computer graphics have become incompatible, and a device that outputs reproduced image information has been desired. As such image information output devices, printer output devices such as inkjet type, electrophotographic type, or thermal transfer type have been developed.

Among these various printer output devices, thermal transfer printer output devices have a relatively simple mechanism and are easy to handle. Furthermore, they produce less noise during printing, and they are similar to color photos. It has the advantage of producing excellent color images with continuous tone.

Such thermal transfer type printers include a sublimation type that uses a heat-sublimable dye as a coloring material, and a melt-type printer that uses a heat-melting binder and a pigment as a coloring material. The principle of printing by these thermal transfer recording type printers is that an ink ribbon for thermal transfer recording, which has an ink layer on one surface of the substrate, and image receiving paper (transfer sheet) are used. The ink ribbons are placed one on top of the other so as to face each other, and heated, for example, from the base side of the ink ribbon by a printer's thermal head (thermal head), thereby transferring the coloring material in the ink layer of the ink ribbon for thermal transfer recording onto image-receiving paper.

By the way, when comparing the sublimation type and the melting type of thermal transfer methods, the sublimation type is generally inferior to the melting type in terms of storage stability of the ink ribbon, sensitivity, dye density of the recorded image, and gloss of the image surface. However, it has the major advantage of being able to obtain high-resolution and high-quality recorded (printed) images, and the development of applications for dye-sublimation printers is progressing in a direction that will maximize these advantages. Particularly in recent years, the pixel density of thermal heads has improved, and there is a trend towards higher quality layers.

[Problem to be solved by the invention]

However, even with improved resolution, images recorded on conventional dye-sublimation thermal transfer recording paper lack gloss due to the low surface smoothness of the image-receiving layer, and suffer from local defects due to the lack of color material transfer. This may occur, resulting in a decrease in image quality. In this respect, the current situation is that it is considerably inferior to color prints of silver halide photographs.

Until now, as a method to improve the surface gloss of receiver paper,
Several proposals have been made. For example, JP-A-62-
Japanese Patent No. 132680 discloses a technique of smoothing the printed surface of image-receiving paper using a heated roller after thermal transfer recording, and attempts to obtain a clear recorded image with high gloss. However, this method is not desirable because it requires adding another mechanism to the thermal transfer printer, which is mechanically simple.

In addition, Japanese Patent Application Laid-open No. 62-211195 describes a method for improving the surface smoothness of image-receiving paper, in which a mixture that is easily dyed with vaporizable dyes is formed by a cast coating method, and the surface of the image-receiving layer is coated. A technique is described that attempts to improve the image quality of image receiving paper having a Bekk smoothness of 1000 seconds or more. However, it is difficult to obtain a receiving paper free of defects such as so-called white spots, simply because the Bekk smoothness is 1000 seconds or more, and furthermore, the surface quality is not determined only by the Bekk smoothness, but also by three-dimensional Surface roughness is also important.

The above-mentioned conventional methods are insufficient to obtain such recorded images with high gloss and high quality, and all of them have drawbacks.

[Means to solve the problem]

The present invention provides an image-receiving paper for thermal transfer recording, which has an image-receiving layer to which a coloring material is transferred from an ink ribbon for thermal transfer recording, and an image-receiving paper base that holds this image-receiving layer, wherein the Bekk smoothness of the surface of the image-receiving layer is 2500 seconds or more and center surface average roughness is 0
．． The above problem has been solved by providing an image receiving paper for thermal transfer recording having a thickness of 1 μm or less.

[Disclosure of the invention]

The inventors of the present invention have been earnestly promoting research and development of image-receiving paper for dye-sublimation thermal transfer recording. The applicant believed that it was important that the hard copies of the images could be obtained using a conventional thermal transfer printer output device, and in Japanese Patent Application No. 63-73757, the applicant has already proposed an intermediate layer made of an ultraviolet curable resin on the image-receiving paper base. , and an image-receiving layer (color material image-receiving layer) made of ultraviolet ray curing resin or thermosetting resin thereon.
We have proposed an image-receiving paper for thermal transfer recording formed with the following. All of these provide an image-receiving paper that can provide a high surface gloss similar to that of a silver halide photograph.

Thereafter, as a result of continuing research and development, the present inventors succeeded in obtaining a silver halide photographic-like image receiving paper with a high surface gloss and fewer defects such as white spots than those of the above-mentioned prior applications. Conventionally, surface properties are often defined by Bekk smoothness. Although surface glossiness can certainly be discussed in terms of Bekk smoothness, it has been found that this is insufficient for evaluating the quality of recorded images, such as white areas. That is, high image quality can be achieved by specifying not only the Bekk smoothness but also the center plane average roughness of the surface of the receiving layer as described above. With a receiving layer that satisfies these two conditions, a silver halide photographic-like recorded image can be obtained.

As a result of comparative studies with silver salt photographs, the present inventors confirmed that at least a surface gloss of 100% or more is required in terms of glossiness. It has been found that for this purpose, the Bekk smoothness of the image receiving layer should be set to 2500 seconds or more. Furthermore,
It has also been discovered that in order to uniformly transfer the sublimable dye, it is sufficient to suppress the center surface average roughness of the surface of the receiving layer to 0.1 μm or less. This center surface average roughness is 0.1μ
m or more, an air layer is formed between the ink layer of the ink ribbon for thermal transfer recording containing a sublimable dye and the surface of the image receiving layer,
It has been found to inhibit the transfer of sublimable dyes. As a result, some pixels are not dyed with the sublimable dye, resulting in a defect called white spots.

〔Example〕

Regarding specific examples of the image receiving paper for thermal transfer recording of the present invention,
This will be explained with reference to the drawings. FIG. 1 is an enlarged partial sectional view of an image receiving paper 10 for thermal transfer recording according to the present invention, and FIG. 2 shows the state of dyeing during thermal transfer recording. Figure 2 (^) shows the case when conventional image receiving paper is used, and Figure 2 (B)
FIG. 1 is a schematic diagram when the image-receiving paper of the present invention is used. In Fig. 1, 1 is the image receiving paper base (hereinafter also simply referred to as "base").
, 2 indicates the (coloring material) receiving layer, and in FIG. 2, 3
4 is an ink ribbon substrate for thermal transfer recording, 4 is an ink layer, and 5 is not a thermal head.

Figure 2 (A) shows that the center surface average roughness of the image receiving layer 2 is 0.1 μm.
The above shows that the sublimable dye is transferred more often to the convex portions 6 on the surface of the image-receiving layer during thermal transfer, and less is transferred to the concave portions 7, which tends to cause unevenness. On the other hand, in the image receiving paper of the present invention having a receiving layer with a center surface average roughness of 0.1 μm or less, the surface of the image receiving layer 2 has few irregularities as shown in FIG. The sublimable dye is transferred almost uniformly.

Here, as the substrate 1, well-known synthetic paper, general paper,
A plastic film or the like is used.

Specifically, the synthetic paper is polypropylene resin-based Yubo (manufactured by Tamako Yuka Synthetic Paper Co., Ltd.), and the paper paper is art paper or coated gium (for example, Shintomi Paper Co., Ltd., Chrome Wrap or Kanzaki Paper Co., Ltd.). Nisnifun pack) etc. can be used. Further, when used as a transbearing range for OHP etc., it is preferable to use a transparent plastic film as the substrate 1. Further, the image receiving layer 2 mainly contains an ultraviolet curable resin. Image-receiving layer 2 with Bekk smoothness of 2500 seconds or more without post-processing such as supercalentor during manufacturing.
In order to obtain this, an ultraviolet curable resin is most effective as the receiving layer resin. Furthermore, the ultraviolet curable resin can provide an extremely smooth surface of the image-receiving layer by irradiating the resin with ultraviolet rays after coating. This makes it possible to achieve a center surface average roughness of 0.1 μm or less. Furthermore, in order to improve the dyeability of the sublimable dye to the image-receiving layer 2, a thermoplastic resin can be mixed.

Incidentally, the image-receiving layer composition may be one made of an ultraviolet curable resin containing an ultraviolet curable resin as a main component, to which a photopolymerization initiator, a diluent, etc. are added. Here, as the ultraviolet curable resin, commercially available monofunctional or bifunctional acrylates, or polyfunctional acrylates having trifunctionality or more can be used. Examples include neopentyl glycol diacrylate, trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, and the like.

Alternatively, a photopolymerizable oligomer (prepolymer) can also be used.

Examples of these oligomers include epoxy acrylate, polyester acrylate, polyurethane acrylate, polyether acrylate, oligoacrylate, alkyd acrylate, and polyol acrylate. These oligomers generally have a high viscosity, so they can be applied to the substrate by coating methods such as gravure coaters and reverse coaters.
It is necessary to dilute it when applying it. In that case, diluting with a common solvent such as methyl ethyl getone or toluene, or diluting with a monomer called a reactive diluent, such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, Examples include acrylate and diethylene glycol diacrylate.

Furthermore, a photopolymerization initiator is added to cause an ultraviolet curing reaction. Examples of these include self-cleavable benzyl dimethyl ketal (trade name: Nilgacure 651), benzoin, and benzoin alkyl ether. Further, there is no particular problem in using hydrogen abstracting type benzophenone, benzyl, etc., and the amount of photopolymerization initiator added is usually 0.1 to 10% by weight.

A thermoplastic resin can be added to such an ultraviolet curable resin composition. As the thermoplastic resin, a linear saturated polyester resin having high affinity with sublimable dyes is mainly used. Furthermore, a release agent is added to prevent thermal adhesion with the ink ribbon for thermal transfer recording during thermal transfer. As the mold release agent, a silicone-based or fluorine-based resin can be used. This image-receiving layer composition is coated onto the substrate 1 by a well-known method such as a gravure coater, reverse coater, knife coater, or the like. After coating, it is cured by UV irradiation. As a result, an image-receiving layer 2 with extremely high smoothness can be obtained.

Next, some specific examples will be described. Note that the units in the text are parts by weight.

<Example 1> Synthetic paper (manufactured by Tamago Oil Synthetic Paper) with a thickness of 150 μm was used as the substrate 1, and the following image-receiving layer composition was applied onto the substrate 1 using a doctor blade so that the film thickness after curing would be 10 μm. It was coated with. After coating, it was irradiated with a high-pressure mercury lamp (80 W/am, irradiation distance 10 ann), and then passed through a drying oven at 100° C. for curing to obtain an image-receiving paper for thermal transfer recording.

☆Image receiving layer composition f! I: ■Polyester acrylate (UV-curable resin oligomer)...60 parts by weight ■Neopentyl glycol diacrylate (UV-curable resin reactive diluent)...40 n■Benzyl dimethyl ketal (photopolymerization initiator)...・・・・・・・・・・・・・・・
・・・10n■ Silicon acrylate (silicon-based mold release agent)・・・・・・・・・・・・・・・
... 5)) ■Titanium oxide (inorganic pigment)...
・・・・・・・・・・・・ 1 Horn <Example 2> Instead of the image-receiving layer composition of Example 1, the following image-receiving layer composition was used, and an image-receiving paper was prepared in the same manner as in Example 1. Don't make it.

☆Image-receiving layer composition: ■Polyester acrylate・・・・・・・・・・・・
42 parts by weight ■ Diethylene glycol diacrylate (ultraviolet curable resin reactive diluent)...28 Horn ■ Benzyl dimethyl kecool...7
n■Linear saturated polyester resin・・・・・・・・・・・・
・3Qn■Silicone oil ・・・・・・・・・・・・
・・・・・・・・・ 5 rノ ■Titanium oxide
・・・・・・・・・・・・・・・・・・ l 71■
Methyl ethyl getone (diluent)...5017■
Toluene (diluent) ・・・・・・・・・・・・・・・
...5017 Comparative Example 1> An image receiving paper was prepared in the same manner as in Example 1 except that the following image receiving layer composition was used instead of the receiving layer composition of Example 1.

☆Image-receiving layer composition: ■Epoxy acrylate・・・・・・・・・・・・・・・
...18 parts by weight ■Neopentyl glycol diacrylate...12
■Benzyl dimethyl ketal・・・・・・・・・・・・
3 77■Linear saturated polyester resin・・・・・・
・・・・・・7Qn■Silicone oil ・・・・・・
・・・・・・・・・・・・ 5 11 ■Titanium oxide
・・・・・・・・・・・・・・・・・・ l
71 ■ Methyl ethyl getone ・・・・・・・・・・・・
・・・12071■Toluene ・・・・・・
......120 Comparative Example 2 An image-receiving paper was prepared in the same manner as in Example 1, using the following image-receiving layer composition instead of the image-receiving layer composition of Example 1.

☆Image-receiving layer composition: ■Linear saturated polyester resin...100
Part by weight ■ Silicone oil ・・・・・・・・・・・・
・・・・・・・・・ 5 n ■ Titanium oxide ・・
・・・・・・・・・・・・・・・・・・ 1 Horn■Methyl ethyl ketone ・・・・・・・・・・・・・・・170
11■Toluene・・・・・・・・・・・・
...170++ Comparative Example 3> Cast coated paper (manufactured by Kanzaki Paper Co., Ltd. 1 tsubo 1157
g/+rr) and the image-receiving layer composition of Example 2 to prepare an image-receiving paper.

In order to evaluate the characteristics of the image-receiving paper for thermal transfer recording of each of the above Examples and Comparative Examples, an ink ribbon for thermal transfer recording was prepared. First, the following ink composition was coated with a gravure coater on the side opposite to the surface coated with the slipping layer of a 6 μm thick polyester film coated with a heat-resistant slipping layer to obtain an ink ribbon for recording.

★Ink composition: ■Kayaset Blue (sublimation dye)...5
Part by weight ■Linear saturated polyester resin・・・・・・・・・
・・・・・・・・・1 horn■Cellulose acetate propionate...4 n■Methyl ethyl getone...
・・・・・・・・・・・・・・・・・・・・・50〃■Toluene ・・・・・・・・・・・・・・・・・・・・・
・・・・・・4 QnFor the image receiving papers for thermal transfer recording of each example and each comparative example obtained in this way, the image receiving layer of each image receiving paper and the ink layer of the ink ribbon were stacked facing each other. (See Figure 2), heating resistor density is 8 dots/
Thermal transfer recording (printing) was performed using a normal printer output device (sublimation type thermal transfer recording device 1 not shown) having a thermal head 5 of ILM. The results are shown in Table 1. The measurement methods for each of the above items are as follows.

(1) Smoothness: Measured using an Ouken Beck smoothness meter ■ Glossiness = 60° Specular gloss ■ Surface roughness: Three-dimensional surface roughness 5Ra (4) Image quality: The number of defects is determined by 3 levels for white areas As shown in Evaluation Table 1, both Examples 1 and 2 had high surface glossiness and very small surface roughness, so that high quality images were obtained. On the other hand, Comparative Example 3 had good surface gloss but had large surface roughness, resulting in poor image quality. Comparative Examples 1.2 had low smoothness and large surface roughness, and were evaluated as having poor image quality. In detail, it was determined that the image quality was good if the Bekk smoothness of the surface of the image-receiving layer was about 2,500 seconds or more and the surface (center surface average) roughness was about 0.1 μm or less.

〔effect〕

According to the present invention, it is possible to provide an image receiving paper for thermal transfer recording which has sufficiently high surface gloss and Bekk smoothness and has sufficiently small three-dimensional surface roughness, and therefore can be used as a dye-sublimated image receiving paper. When used as recording paper for a thermal transfer recording device, it is possible to obtain a clear, high-quality recording surface @ (hard copy). It has an excellent effect of greatly contributing to promotion and early dissemination.

[Brief explanation of the drawing]

FIG. 1 is an enlarged partial sectional view of the image receiving paper for thermal transfer recording of the present invention, and FIGS. 2 (8) and (B) are images of printing by a thermal head using the conventional image receiving paper for thermal transfer recording and the image receiving paper of the present invention, respectively. FIG. DESCRIPTION OF SYMBOLS 1... Image receiving paper base, 2... Image receiving layer, 3... Ink ribbon base, 4... Ink layer, 5... Thermal head, 6... Convex part (dye dyed part), 7... Concavity (undyed area), 10... Image receiving paper for thermal transfer recording. Patent applicant: Kunio Umiki, representative of Victor Japan Co., Ltd.

Claims (1)

[Claims] An image receiving paper for thermal transfer recording, comprising an image receiving layer to which a coloring material is transferred from an ink ribbon for thermal transfer recording, and an image receiving paper base holding the image receiving layer, wherein the Bekk smoothness of the surface of the image receiving layer is 2500 seconds or more. An image receiving paper for thermal transfer recording, characterized in that the center surface average roughness is 0.1 μm or less.