JPH07117323A - Method for forming applied layer - Google Patents

Abstract

PURPOSE:To lessen the generation of irregularities in images resulting from an adhering irregularity of an ink layer by applying a paint of the same composition onto a sheet-like body a plurality of number of times by a screen printing method and forming an applied layer. CONSTITUTION:A paint of the same composition is applied onto a sheet-like body (base) 1 a plurality of number of times by a screen printing method to form an applied layer 2, whereby a heat-sensitive recording medium is obtained. More preferably, a method may be employed whereby the paint is overcoated on the base a plurality of number of times with the use of at least two kinds of screens of different mesh sizes. According to the screen printing method, an irregularity in an adhering amount of the applied layer generated at the first coating time is reduced because much paint is effectively adhered at the second time of coating to a part of the first applied layer where a small amount of paint is adhered. The effect is further increased at the third time of coating, thereby eliminating the irregularity in the adhering amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a coating layer on the surface of a sheet-like material, and more specifically, it uses a screen printing coating method to provide a uniform coating amount (coating amount) that is uniform. The present invention relates to a method for forming a coating layer in which a layer is obtained.

[0002]

2. Description of the Related Art In recent years, as a recording method for a color printer, attention has been paid to a method of sublimating and transferring a sublimable dye from a transfer medium onto a recording sheet by using a thermal head or a laser beam for recording. Used in this sublimation thermal transfer recording system,
In a thermal transfer recording medium in which an ink layer in which a sublimation dye is dispersed in a resin binder is provided on a support, an experiment was conducted to make the transferred image poor if there was slight coating unevenness in the ink layer. Confirmed by. In particular, in the so-called n-times mode method, in which the speed of the image receiving sheet is set to n times the speed of the ink sheet (n> 1), and both sheets are repeatedly printed, the so-called n times mode method is used. The printing is performed many times by the relative speed method in which the sheet is conveyed while being slightly overlapped with the used portion in the subsequent times, and is also called a speed difference method. In the multi-time recording by the n-fold mode method, since a part of the unused portion of the ink layer is always supplied every time printing is performed, the multi-time recording by the constant velocity mode method is merely a repeated use of the used portion. Compared with the one-time ribbon, the n-times mode ribbon has a 1-n coating width compared to the one-time ribbon, and at the same time has the advantage of being able to reduce the variation in the remaining ink amount due to the recording history. Must also be increased. Therefore, narrow the width to 3 for yellow, magenta, cyan, and black if necessary.
Ink layers of four colors or four colors must be sequentially provided on the long support sheet and coated relatively thickly. Therefore, the inventors of the present invention have found that the screen printing coating method, which employs the screen printing method when a large number of kinds of coatings are thickly provided in a narrow region perpendicular to the longitudinal direction of the sheet, is excellent in coating cost. Recalled.

[0003]

However, although the ink layer applied by the screen printing method is excellent in thick and narrow application of the ink layer, it causes uneven adhesion of the ink layer as shown in FIG. This causes image unevenness on the image receiving sheet. The drawback of this image unevenness is
According to the double mode method, the image is enlarged by n times and printed.
The present invention has been made in view of such drawbacks, and a method for reducing unevenness in the amount of adhesion that occurs in a coating layer by a screen printing coating method, in particular, an ink layer of a sublimation type thermal transfer recording medium is formed by screen printing coating. It is an object of the present invention to provide a method for reducing the occurrence of image unevenness due to unevenness in the amount of ink layer adhesion that occurs.

[0004]

According to the present invention, firstly, in a method for forming a coating layer on a sheet-shaped object, a coating composition having the same composition is applied multiple times by a screen printing coating method. There is provided a method for forming a coating layer, which comprises forming a thicker coating layer. Secondly, in the first method, there is provided a coating layer forming method in which at least two kinds of screens having different screen mesh sizes are used and a plurality of times are repeatedly applied. Thirdly, in the first method, there is provided a method for forming a coating layer, in which at least two kinds of screens having different mesh directions are used for multiple application. Fourthly, in the above method, a coating layer forming method for providing a sublimation type thermal transfer recording medium using a coating material comprising a sublimation type dye and an organic binder is provided.

[0005]

In the first screen printing coating method, the coating composition having the same composition is applied a plurality of times so that the unevenness of the amount of the coating layer caused by the first coating is applied to the first small amount coating portion by the second coating. The effect of adhering a large amount of paint is obtained, and uneven coating amount is reduced (see FIG. 1). This effect is further increased by the third application, and uneven adhesion amount is not seen (see FIG. 2).

In the second method, a plurality of screens having different screen mesh sizes are used for the above-mentioned multiple coatings, so that the first small amount adhered portion is more than the case where the same mesh size is coated a plurality of times. The effect of adhering the paint is obtained, and unevenness of the adhering amount is reduced. In this case, it is preferable to reduce the screen mesh size in the upper layer (multiple) direction.

In the third method, the above-mentioned multiple coatings are carried out by using a plurality of screens having different directions of the gauze. The effect that the paint adheres is obtained, and the unevenness of the adhered amount is reduced.

In the fourth method, the ink layer of the sublimation type thermal transfer recording medium is formed by the above-mentioned first, second or third method, whereby a good recorded image without unevenness can be obtained. Applied to a method for coating and forming a dye supply layer of a transfer medium (JP-A-2-586) in which a dye supply layer having a relatively high dye density and a thin transfer contributing layer having a relatively low dye density are sequentially laminated on a sheet. In this case, it is possible to obtain the effect that no image unevenness is observed when recording is performed in the n-fold mode using this recording medium.

[0009]

Embodiments will be specifically described below with reference to embodiments. Although the examples were carried out with respect to the production of a sublimation type thermal transfer recording medium, the present invention is not limited to this. The amounts (parts) of the respective components shown below are all parts by weight.

First, the formulations of the substrate and the coating solution commonly used in each Example and Comparative Example are shown below. Further, the production of each sublimation type thermal transfer recording medium was commonly carried out by providing an intermediate layer having a thickness of 1.0 μm on a substrate by a wire bar and applying a dye supply layer thereon. Sublimation dyes are yellow: Yellow VP, magenta: HM-1
041, Cyan: Three colors of Ceres Blue were used. <Substrate> Polyamide film having a thickness of 6 μm and having a 1 μm thick silicone resin heat-resistant layer provided on the back surface <Intermediate layer forming liquid> Polyvinyl butyral resin 10 parts 2-Butanone 90 parts <Dye supply layer forming liquid> A liquid polyvinyl Butyral resin 7 parts Sublimation dye HM-1041 30 parts Benzyl alcohol 100 parts Diisocyanate 3 parts Solution B Polyvinyl butyral resin 7 parts Sublimation dye HM-1041 30 parts Benzyl alcohol 150 parts Diisocyanate 3 parts

Example 1 Dye supply layer A liquid was applied at 250 mesh / inch for the first time and 250 mesh / inch for the second time, and the thickness is 5 to 6 μm.
And Each application was dried at 120 ° C. for 10 minutes.

Example 2 Dye supply layer A liquid was applied at 250 mesh / inch for the first time and 300 mesh / inch for the second time, and the thickness is 5 to 6 μm.
And Each application was dried at 120 ° C. for 10 minutes.

Example 3 The dye supply layer A liquid was applied at the first 250 mesh / inch, the second time and the third time with the dye supply layer B liquid at 420 mesh / inch, and the thickness was 5 to 6 μm. 12 for each application
It was dried at 0 ° C. for 10 minutes.

Example 4 The liquid B of the dye supply layer was applied at 200 mesh / inch for the first time and 300 mesh / inch for the second time, and the thickness is 5 to 6 μm.
And Each application was dried at 120 ° C. for 10 minutes.

Example 5 and Example 6 In Example 1 and Example 2, the second mesh orientation was applied by a plate different from the first mesh orientation by 45 °, and the thickness was 5 to 6 μm. The drying was performed in the same manner as in Examples 1 and 2.

Comparative Example 1 Dye supply layer A liquid was applied at # 180 mesh / inch,
It was dried at 120 ° C. for 10 minutes. The thickness was 5 to 6 μm.

Comparative Example 2 Dye supply layer B liquid was applied at # 100 mesh / inch,
It was dried at 120 ° C. for 10 minutes. The thickness was 5 to 6 μm.

[Preparation of Dye Transfer Contribution Layer and Low Dyeing Resin Layer] Next, a dye transfer contribution layer forming liquid having the following composition was added to each of the dye supply layers prepared in the above Examples and Comparative Examples with 300 mesh / inch. And apply it to a film thickness of 1.0 μm.
It was dried at 0 ° C. for 10 minutes. Further, a low-dyeing resin layer forming liquid having the following composition was applied to the uppermost layer with a wire bar so as to have a film thickness of 0.7 μm. Then, it hold | maintained at 60 degreeC for 24 hours, the coating film was hardened, and it used for the test.

<Dye transfer contributing layer forming liquid> Polyvinyl butyral resin 10 parts Sublimation dye HM-1041 20 parts Diisocyanate 3 parts Cyclohexanone 170 parts <Low dyeing resin layer forming liquid> Methyltrimethoxysilane 2
8 g was dissolved in a mixed solution of 50 g of toluene and 50 g of 2-butanone, 3 ml of 3% sulfuric acid was added, and hydrolysis was performed for 3 hours. This liquid is referred to as liquid C. Styrene-maleic acid copolymer 5 parts C liquid 20 parts Tetrahydrofuran 20 parts

[Preparation of Image Receiving Sheet] Next, an image receiving sheet used for evaluation was prepared as follows. An intermediate layer and an image receiving layer forming solution having the following compositions were sequentially coated on a synthetic paper (Yupo FP-150 manufactured by Oji Yuka Synthetic Paper Co., Ltd.) having a thickness of about 150 μm, and each layer was dried at a drying temperature of 75 ° C. for 1 minute. Formed. Then, it was held at 60 ° C. for 24 hours to be cured to obtain an evaluation image-receiving sheet. <Intermediate layer forming liquid> Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 10 parts Diisocyanate 5 parts Toluene 40 parts 2-Butanone 40 parts <Image receiving layer forming liquid> Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 10 parts Diisocyanate 5 parts Amino acid silicone oil 0.5 part Epoxy modified silicone oil 0.5 part Toluene 40 parts 2-Butanone 40 parts

[Evaluation Test] The sublimation type thermal transfer recording medium and the image receiving sheet obtained as described above were mounted on a heat applying device using a thermal head, and the dye in the ink layer (dye supply layer) was placed on the image receiving sheet under the following printing conditions. It was transferred to and the image unevenness was visually evaluated. The evaluation results are shown in Table 1 below. <Printing conditions> Thermal head resolution: 12 dots / mm Applied energy: 0.64 mJ / dot Applied power: 1.6 w / dot Image receiving sheet feed speed: 8.4 mm / sec Recording medium feed speed: 0.56 mm / sec

[0022]

[Table 1]

From Table 1, it is understood that according to the coating method of the embodiment, the area where density unevenness occurs is limited. Especially 2
If the mesh size of the second time is made smaller (see Example 4), or if the mesh size is made smaller both times, the area where uneven density is generated is further limited (see Example 2). No occurrence is seen (see Example 3). Also, when the orientation of the gauze is changed the first time and the second time, the density unevenness generation area is more limited (see Example 5). When the mesh is made finer in addition to the orientation of the gauze, uneven density is not observed (see Example 6).

[0024]

As described above, the uneven coating amount of the coating material generated in the coating layer by the screen printing can be remarkably reduced by applying the same coating material a plurality of times by the screen printing. Further, by using this for forming the ink layer of the sublimation type thermal transfer recording medium, uneven density, that is, uneven image is not observed in the transferred image.

[Brief description of drawings]

FIG. 1 is a diagram showing each cross section of an ink layer forming state according to the present invention.

FIG. 2 is a diagram showing each cross section of another example of an ink layer forming state according to the present invention.

FIG. 3 is a plan view when an ink layer is applied on a substrate by screen printing.

FIG. 4 is a plan view showing an example of screens having different mesh directions of the screen mesh used in the present invention.

FIG. 5 is a diagram showing a cross section of an ink layer formed by conventional screen printing coating.

[Explanation of symbols]

 1 substrate 2 ink layer 3 screen mesh

Claims (4)

[Claims] 1. A method for forming a coating layer on a sheet-shaped article, comprising forming a coating layer by coating a coating composition having the same composition a plurality of times by a screen printing coating method. Method. 2. The method for forming a coating layer according to claim 1, wherein at least two kinds of screens having different screen mesh sizes are used and the coating is repeated a plurality of times. 3. The method for forming a coating layer according to claim 1 or 2, wherein at least two kinds of screen meshes having different mesh directions are used and the coating is repeated a plurality of times. 4. The method for forming a coating layer according to claim 1, wherein a coating material comprising at least a sublimation dye dispersed in an organic binder is used.