JPH09234961A - Manufacture of heat transfer accepting sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accepting sheet, which has no scatter in respective products and is remarkably stable in recording sensitivity and in the color hue and color tone of an image in the accepting sheet having high picture quality at high speed print and high storage stability and running stability. SOLUTION: A resin coated sheet is produced by applying a coating solution mainly containing dye printable resin on the surface of a sheet-like support and drying the solution. Then, by applying a humidifying process from the rear surface side of the shet-like support, the water content of the whole resin coated sheet is set to be 350-3,000ppm. After that, by performing curing treatment to the resin coated sheet, an image accepting layer having the water content of 600-9,000ppm is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermal transfer receiving sheet (hereinafter simply referred to as a receiving sheet). More specifically, the present invention, when used in a thermal (thermal recording) printer, especially a dye thermal transfer printer, is capable of receiving with high sensitivity an image of an image forming dye such as a thermally transferred sublimable dye. Further, the present invention relates to a receiving sheet capable of stably reproducing the print sensitivity and the hue and tone of an image as described above.

[0002]

2. Description of the Related Art In recent years, a thermal printer, especially a dye thermal transfer printer capable of printing a clear full-color image has attracted attention. A dye thermal transfer printer is an image shape to which the dye of the ink layer is to be transferred by heat supplied from a thermal head, etc., by superimposing the image receiving layer containing the dye-dyeing resin of the receiving sheet on the ink layer of the dye ink sheet. According to the above, the image is formed by transferring the image on the image receiving layer at a predetermined density. The ink sheet is a dye ink sheet of three colors of yellow, magenta and cyan, or four colors obtained by adding black to this. A full-color image is obtained by sequentially and repeatedly transferring the dyes of the ink sheets of the respective colors described above onto the image-receiving layer of the receiving sheet. Recent dye thermal transfer printers are required to be able to transfer an image of high quality and high storage stability onto a receiving sheet by a high speed printing operation.

In such a high-sensitivity receiving sheet of a dye thermal transfer printer, the image-receiving layer plays an important role. In order to obtain a high-sensitivity receiving sheet, a resin having a high dye-dyeability is used as a main component of the image receiving layer. However, in a receiving sheet having an image receiving layer containing such a dye-dyeable resin as a main component, the releasability between the ink sheet and the receiving sheet is lowered, and the running property of the receiving sheet during printing operation deteriorates. Or, the storage stability of the received image is reduced.

In order to solve the above problems,
Generally, a crosslinking agent, an anti-fusing agent, an ultraviolet absorber, etc. are added to the image receiving layer. However, even if an image recording having high image quality and high storage stability in a high-speed printing operation is thereby achieved, it may be because the image receiving layer contains a highly reactive crosslinking agent and various additives. However, the print sensitivity and hue / tone were not stable, and variations among the products were conspicuous, which was unsatisfactory for practical use.
In recent years, with the increase in sensitivity, recording sensitivity and hue
The appearance of a receiving sheet having a stable color tone is desired.

[0005]

SUMMARY OF THE INVENTION The present invention is a receiving sheet having high image quality, high storage stability, and running stability even in high-speed printing, and has extremely stable recording sensitivity without variations due to product quality. Another object of the present invention is to provide a receiving sheet having the hue and tone of an image.

[0006]

The method for producing a thermal transfer receiving sheet of the present invention comprises applying a coating liquid containing a dye-dyeing resin as a main component onto the surface of a sheet-like support, drying the resin coating layer. To form a resin-coated sheet, and subjecting the sheet-shaped support to a humidification treatment from the back side to adjust the water content of the entire resin-coated sheet to 350 to 3,000 ppm,
Then, the resin coated sheet is cured to give 6
An image receiving layer having a water content of 00 to 9,000 ppm is formed. In the method for producing a thermal transfer receiving sheet of the present invention, the coating liquid further contains a polyisocyanate compound, and the dye-dyeable resin is crosslinked with the polyisocyanate compound by the drying and curing treatments.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In order to reduce variations in quality in the print sensitivity of each product of a receiving sheet and the hue / tone of a transferred image, the inventors of the present invention relate to, for example, seasonal changes in the manufacturing environment. As a result of intensive studies, it was found that the object of the present invention can be achieved by adjusting the water content of the image receiving layer of the receiving sheet to a predetermined value. That is, in a receiving sheet obtained by applying a resin coating solution for an image receiving layer on one surface of a sheet-like support, drying the same, and further performing a curing treatment, the water content of the image receiving layer is It has been found that it is very closely related to the print sensitivity of the layer and the stabilization of the hue and tone of the transferred image.

In the present invention, the receiving sheet is subjected to curing treatment so that the water content of the image receiving layer is 600 to 9,0.
It is important to adjust it to 00 ppm, and the preferable water content is 1,500 to 9,000 ppm. The receiving sheet of the present invention is excellent in image quality and storage stability of images even in high-speed printing, and is excellent in running stability of the receiving sheet, and has extremely stable recording with no quality variation among products throughout the year. A receiving sheet having sensitivity and image hue / tone is obtained. On the other hand, when the water content of the image receiving layer is less than 600 ppm, the print sensitivity of the image receiving layer and the hue / tone of the obtained image become unstable, and the variation in quality among products increases. Further, when the water content of the image receiving layer exceeds 9,000 ppm, the printing sensitivity decreases.

In the present invention, the method for adjusting the water content of the image-receiving layer is as follows. A resin coating solution for the image-receiving layer is applied on the surface of a sheet-like support and dried to form a resin coating layer.
The sheet-shaped support is humidified from the back side using a humidifier or the like to adjust the water content of the entire sheet-shaped support (resin-coated sheet) on which the resin coating layer is formed to 350 to 3,000 ppm, and thereafter, an appropriate amount. Since the curing treatment is performed, the water content of the image receiving layer can be adjusted to a desired range of 600 to 9,000 ppm. Usually, the moisture content of the image-receiving layer obtained when the curing treatment is performed without the humidification treatment is about 500 ppm or less.

In the present invention, although not particularly limited, the resin-coated sheet whose water content is adjusted to 350 to 3,000 ppm is wound into, for example, a roll, packaged if necessary, and cured. Alternatively, the sheet may be cut, and a sheet having a predetermined moisture content may be sealed in a moisture-proof bag, and then cured. The curing treatment conditions vary depending on the type of the crosslinking agent and other components and are not particularly limited, but the curing treatment performed after humidifying the resin coated sheet is usually 40 to 70 ° C. for about 24 hours, or The above is preferable. The present invention is characterized in that the sheet-like support on which the resin coating layer serving as the image receiving layer is formed is subjected to a humidification treatment from the back side, and by not humidifying the receiving layer directly, the unevenness of the white surface and the unevenness of the printed surface are obtained. Can be prevented.

In the present invention, the water content of the image receiving layer is
It was measured by the Karl Fischer method using a trace amount moisture meter (trademark: CA-06, manufactured by Mitsubishi Kasei) and a moisture vaporizer (trademark: VA-06, manufactured by Mitsubishi Kasei). However, the method for measuring water content is not limited to the above method. For example, a gas detector tube (trademark: 177SA, or 177
U, manufactured by Komei Rika Kagaku Kogyo Co., Ltd.).

In the receiving sheet of the present invention, an image receiving layer for receiving the dye image of the ink ribbon is provided on one surface of the sheet-like support, and if necessary, the image receiving layer of the sheet-like support is provided on the opposite side. You may have the back surface coating layer provided in the surface. Further, an intermediate layer may be provided between the sheet-shaped support and the image receiving layer.

The image receiving layer in the present invention may contain a crosslinking agent, an anti-fusing agent, an ultraviolet absorber and the like in addition to the dye-dyeing resin. The image receiving layer contains a dye-dyeing resin as a main component. As the resin having a high dye-dyeability, an acetate butyrate-based resin, a polyester-based resin or the like is used. Further, as the cross-linking agent, an isocyanate compound, an epoxy compound or the like is used. Although the amount of the cross-linking agent used depends on the type, it is usually preferably about 2 to 25% by weight based on the dye-dyeing resin. In particular, when a polyisocyanate compound is used as the crosslinking agent for the image receiving layer, the effect of stabilizing the quality of the receiving sheet of the present invention is remarkable. Further, as the anti-fusing agent, a modified silicone oil such as alcohol-modified silicone oil, amino-modified silicone oil, and epoxy-modified silicone oil, an acrylic silicone resin, a lubricant and a mold release agent are used. Triazole-based, benzophenone-based, phenyl salicylate-based, cyanoacrylate-based UV absorbers and the like are used.

In the receiving sheet of the present invention, by adjusting the water content of the image receiving layer within a specific range, the print sensitivity of the image receiving layer and the hue / tone of the image formed thereon are remarkably stabilized. , Quality variation among products is significantly reduced. The reason has not been fully clarified, but the following factors are considered. Usually, the image receiving layer component contains a reactive crosslinking agent, so that a competitive reaction between various materials and the crosslinking agent may occur in the image receiving layer. Depending on the type of crosslinker, this competitive reaction should also be affected by the presence of water.
In particular, when a polyisocyanate compound is used as a crosslinking agent, the presence of water promotes the crosslinking reaction between the isocyanate groups. Therefore, if the water content in the image-receiving layer changes with changes in the production conditions, the competitive reaction may be easily affected. As a result, in each product, the composition of the image receiving layer, that is, the ratio of the reaction product and the unreacted product of the competitive reaction, or the structure of the reaction product is different, and the heat transfer characteristics and dye transferability of the image receiving layer are different. It seems that the print sensitivity of the image-receiving layer and the hue / tone of the transferred dye image are not stable due to the change of the image. Therefore, it is considered that by controlling the water content of the image receiving layer to be constant, various reactions can be stabilized and the excellent effects of the present invention can be obtained.
In addition, it is conceivable that the image receiving layer may also contain an appropriate amount of water to obtain an antistatic effect, improve recording runnability, and obtain stable hue and tone.

In the receiving sheet of the present invention, the thickness of the image receiving layer is preferably 1 to 10 μm, more preferably 2 to 7 μm. If the thickness of the image receiving layer is less than 1 μm, the density and sensitivity of the thermal transfer dye image may be reduced, or the gloss of the printed surface may be reduced. If it exceeds 10 μm, the effect of the image receiving layer is saturated, which is uneconomical and the strength of the image receiving layer may be rather lowered. The coating amount of the image receiving layer is preferably about 3 to 10 g / m ² in dry weight.

The sheet-like support used in the receiving sheet of the present invention is preferably a film-like substrate, and may be, for example, a laminate of plastic sheets.
In this case, it is preferable that the receiving sheet has a laminated structure that can avoid deformation due to heat when printed. In the present invention, synthetic paper is a typical example of the plastic sheet used as the sheet-shaped support. In such a synthetic paper, a biaxially stretched thermoplastic resin film is used as a base film, and a uniaxially stretched thermoplastic resin paper-like layer film is laminated on the surface thereof. Since this paper-like layer film contains filler particles, and the stretching thereof forms microvoids in the vicinity of the filler particles, it has good writability and a texture close to that of natural paper. The inorganic pigment used as the filler for the paper-like layer film is selected from, for example, clay, talc, gypsum, barium sulfate, diatomaceous earth, silicon oxide, and other white pigments, and they are used alone or in combination.

The thermoplastic resin used in the synthetic paper for the support is preferably a polyolefin resin such as a homopolymer or copolymer of ethylene, propylene or butene-1, a polyvinylidene resin such as vinylidene chloride. It is selected from homopolymers or copolymers, styrene homopolymers or copolymers, polyester resins, nylon and the like. These can be used alone or as a mixture of two or more kinds. Further, these synthetic paper resins may contain stabilizers, plasticizers, fillers, pigments, and other auxiliary materials in a stretchable range, if necessary. It is preferable that the base film contains a filler in a content of 0 to 3% by weight. When the content of the filler is more than 3% by weight, the mechanical strength of the obtained receiving sheet becomes insufficient. May be. The thermoplastic resin used for forming the paper-like layer film may be the same as or different from the resin for the base film from the above. Generally, the paper-like layer film preferably contains the filler in an amount of 5 to 60% by weight.

In the film-like support used in the present invention, other sheets may be laminated on the synthetic paper containing the above-mentioned stretched thermoplastic resin sheet. As such a laminating sheet, it is preferable to use a film having thermoplasticity and relatively good heat resistance, for example, a polyethylene terephthalate film. As the laminating film, various other synthetic resin films can be used depending on the use conditions. For example, polyvinyl chloride, polyvinylidene chloride, polyethylene, and polystyrene films can be used.

The sheet-like support used in the present invention is 2
It preferably has a thickness of 0 to 300 μm. When the thickness is less than 20 μm, the mechanical strength of the resulting receiving sheet becomes insufficient, and the repulsive force against its hardness and deformation becomes insufficient, and the curling of the receiving sheet at the time of printing is sufficiently prevented. This may cause the inconvenience of not being able to do so. If the thickness exceeds 300 μm, the thickness of the obtained receiving sheet may be excessive. In a printer having a predetermined volume, the capacity of the receiving sheet is limited, and an increase in the thickness of the receiving sheet naturally causes a decrease in the number of receiving sheets of the printer. In this case, in order to accommodate a predetermined number of receiving sheets, it is necessary to increase the volume of the printer, which makes it difficult to make the printer compact.

In the receiving sheet of the present invention, on the surface (rear surface) of the sheet-shaped support opposite to the image receiving layer, the running property is improved, static electricity is prevented, and the image receiving layer is damaged by rubbing between the receiving sheets. A backside coating layer may be formed for the purpose of prevention, and further for preventing transfer of the dye from the image receiving layer to the backside of the receiving sheet adjacent thereto when the printed receiving sheets are stacked.

The back surface coating layer contains a resin effective as an adhesive, and this resin is also effective for the running property of the receiving sheet and the prevention of scratches on the surface of the image receiving layer. As such a resin, an acrylic resin, an epoxy resin, a polyester resin, a phenol resin, an alkyd resin, a urethane resin, a melamine resin, or a reaction cured product of these resins can be used. Further, various conductive agents can be added to the back surface coating layer for antistatic treatment. It is desirable to use a cationic polymer as the conductive agent. As the cationic polymer, polyethyleneimine, an acrylic polymer containing a cationic monomer, a cation-modified acrylamide polymer, a cationic starch and the like can be generally used. The coating amount of the back surface coating layer is preferably in the range of 0.3 to 1.5 g / m ² . If it is less than 0.3 g / m ² , scratches on the image receiving layer may not be sufficiently prevented when the image receiving layer and the back surface of the receiving sheet adjacent thereto are rubbed with each other. If it exceeds m ² , the effect is saturated and it is uneconomical.

In the receiving sheet of the present invention, if necessary,
For example, an intermediate layer is added between the sheet-shaped support and the image-receiving layer as an antistatic layer of the image-receiving layer, a cushioning layer for improving the image density, or an adhesive layer between the image-receiving layer and the sheet-shaped support. can do. The image-receiving layer and other coating layers of the receiving sheet of the present invention, the intermediate layer and the like are coated and dried using a coater such as a bar coater, a gravure coater, a comma coater, a blade coater, an air knife coater, and a gate roll coater. Can be formed.

[0023]

EXAMPLES The present invention will be explained in more detail with reference to the following examples, but of course the present invention is not limited to these examples. In addition, "part" and "%" in the examples are
All are "parts by weight" and "% by weight". Example 1 A PET film having a thickness of 50 μm was used as a core material, and a polyolefin film containing polyolefin as a main component and about 30% of calcium carbonate as an inorganic pigment on both front and back surfaces thereof was biaxially stretched and had a thickness of 60 μm. Structural film (trademark: YUPO F
(PG60, made by Oji Oka Synthetic Paper) was laminated and adhered by a dry lamination method with a urethane type adhesive to prepare a sheet-shaped support. On the back surface of this support, a backside coating layer was formed by applying a paint-2 having the following composition so that the solid coating amount was 1 g / m ^2, and drying. Next, on the surface of this sheet-like support, a paint-1 having the following composition was applied so that the solid content was 8 g / m ^2, and dried to form a resin coating layer. Use a humidifier to humidify the backside coating layer side for 10 minutes to reduce the water content of the entire sheet to 400
After adjusting to ppm, the back surface coating and the resin coating layer are overlapped so as to be in contact with each other, and cured at 50 ° C. for 48 hours,
The water content of the formed image receiving layer was adjusted to 700 ppm to prepare a receiving sheet. Paint-1 (for image receiving layer) Polyester resin (trademark: Byron 200, manufactured by Toyobo Co., Ltd.) 100 parts Silicone oil (trademark: KF393, manufactured by Shin-Etsu Silicon Co., Ltd.) 3 parts Isocyanate (trademark: Takenate D-140N, manufactured by Takeda Pharmaceutical Co., Ltd.) ) 5 parts Toluene 300 parts Paint-2 (for back surface coating layer) Acrylic ester copolymer (trademark: Primal WL-81, manufactured by Rohm and Haas) 100 parts Epoxy resin (trademark: Epocoat DX-225, Shell Chemistry) 5 parts Conductive agent (trademark: Saftomer ST1000, manufactured by Mitsubishi Yuka) 50 parts Denatured ethanol 1420 parts

Example 2 A backside coating layer was formed in the same manner as in Example 1, and the coating material-1 for the image receiving layer was applied and dried to form a resin coating layer, and the backside was further heated at room temperature using a humidifier. Humidify for 20 minutes from the coating layer side to adjust the water content of the entire sheet to 940 ppm,
Next, stack so that the back surface coating layer and the resin coating layer are in contact,
After curing at 50 ℃ for 48 hours, 2,500ppm
An image receiving layer having a water content adjusted to 2 was formed, thereby obtaining a receiving sheet.

Example 3 A back surface coating layer was formed in the same manner as in Example 1, and a coating material-1 for image receiving layer was applied and dried to form a resin coating layer, and the back surface was formed at room temperature using a humidifier. Humidify for 30 minutes from the coating layer side to adjust the water content of the entire sheet to 1,700 ppm, then stack so that the back surface coating layer and the resin coating layer are in contact, and cure at 50 ° C. for 48 hours. , 5,200p
forming an image receiving layer having a water content adjusted to pm,
Thereby, a receiving sheet was obtained.

Example 4 A back surface coating layer was formed in the same manner as in Example 1, and coating material-1 for image receiving layer was applied and dried to form a resin coating layer,
Further, by using a humidifier at room temperature for 60 minutes from the back coating layer side, the water content of the entire sheet is adjusted to 2,800 ppm, and then the back coating layer and the resin coating layer are overlapped so that they are in contact with each other. After curing at ℃ for 48 hours, 8,500
An image receiving layer having a water content adjusted to ppm was formed, thereby obtaining a receiving sheet.

Comparative Example 1 A backside coating layer was formed in the same manner as in Example 1, and coating material-1 for image receiving layer was applied and dried to form a resin coating layer. However, the subsequent humidification treatment was omitted. The water content of the entire sheet was 240 ppm. Next, the back surface coating layer and the resin coating layer were overlapped so as to be in contact with each other, and cured at 50 ° C. for 48 hours to form an image receiving layer having a water content adjusted to 500 ppm, whereby a receiving sheet was prepared. Obtained.

Comparative Example 2 A back coating layer was formed in the same manner as in Example 1, and the coating material-1 for image receiving layer was applied and dried to form a resin coating layer.
Further, by using a humidifier at 30 ° C. to humidify from the back surface coating layer side for 80 minutes, the water content of the entire sheet is adjusted to 3,600 ppm, and then the back surface coating layer and the resin coating layer are overlapped so as to be in contact with each other, Cure at 50 ° C for 48 hours to give 11,0
An image receiving layer having a water content adjusted to 00 ppm was formed, thereby obtaining a receiving sheet.

Evaluation Test For the receiving sheets obtained in each of the above Examples and Comparative Examples, the water content of the image receiving layer, image gradation, print sensitivity, and hue / tone of the image were measured and evaluated. The results are shown in Table 1. The above measurement was performed by the following method. [Water content] The water content is measured by measuring the water content of the resin-coated sheet whose humidity is controlled as described above, or the water content of the receiving sheet, and the moisture content of the sheet-shaped support which is also humidity-controlled by a trace moisture meter (trademark: CA-06, manufactured by Mitsubishi Kasei) and a moisture vaporizer (trademark: VA-06, manufactured by Mitsubishi Kasei) were used, and the water content (ppm) of the image receiving layer was calculated from the difference. [Gradation Reproducibility] The receiving sheet was attached to a sublimation color video printer (trademark: UP5000, manufactured by Sony) so that the image receiving layer surface was printed, and printed in a 16-step pattern. Using a Macbeth densitometer (trademark: RD-914, manufactured by Kollmorgen Corp.), the reflection density was measured for each applied energy, and the gradation reproducibility was evaluated. Gradation reproducibility was evaluated in three grades of ⊚, ∘, and × in order of good reproduction. In addition, ○
Levels and above are suitable for practical use, but levels x are not suitable for practical use. [Print Sensitivity] The print sensitivity was evaluated by printing on a receiving sheet in the same manner as described above and measuring the image density in 10 steps. The print sensitivity and the variation in the print sensitivity are 3 in each of the example and the comparative example.
Printing was performed on each receiving sheet, and the average value of these image densities and the maximum value of the deviation between the average value and the image density of each receiving sheet were determined. The image density (average value) needs to have a sufficient density and a constant value, and the smaller the maximum value of the deviation, the smaller the variation in the image quality. [Hue / tone of image] The hue / tone of the image is printed on a receiving sheet in the same manner as described above, and an image in 10 steps is measured by an optical color difference meter (trademark: CR-321, manufactured by Minolta Co., Ltd.) according to JIS Z. It was measured by the method specified in 8722, and the result was evaluated based on JISZ 8729. The variation of the color display of the image by the (L ^* a ^* b ^* ) color system was printed on 30 receiving sheets in each of the examples and the comparative examples, and the average color display (L ^* , a ^* , And b ^* are the respective average values)
And the maximum value of the color difference ΔE between the color display of each receiving sheet and the color display was obtained. This color difference ΔE was calculated based on JIS Z 8730. It should be noted that the smaller the maximum value of the color difference ΔE, the smaller the variation in image quality. The above results are shown in Table 1.

[0030]

[Table 1]

As is apparent from Table 1, the receiving sheets obtained in each of Examples 1 to 4 had good image gradation, sufficiently high image density, and small deviation in image density (recording). (There is almost no variation in sensitivity), the color difference ΔE is small, and the hue and tone are extremely stable. However, in Comparative Example 1, since the water content of the image receiving layer was too small, the deviation of the image density was large, the color difference ΔE was large, and the hue / tone variation was large. In Comparative Example 2, since the water content of the image receiving layer was excessive, the gradation of the image was poor and the image density was insufficient.

[0032]

EFFECTS OF THE INVENTION The present invention provides a receptor sheet capable of obtaining a highly sensitive printing screen, having no variation in product quality, good printing sensitivity, and capable of extremely stably reproducing the hue and tone of an image. It will be possible and the contribution to the industry will be great.

Claims (2)

[Claims] 1. A sheet-like support, which is prepared by applying a coating liquid containing a dye-dyeing resin as a main component onto a surface of a sheet-like support and drying the resin to form a resin-coated layer to prepare a resin-coated sheet. Is subjected to a humidification treatment from the back side thereof to adjust the water content of the entire resin-coated sheet to 350 to 3,000 ppm, and thereafter, the resin-coated sheet is subjected to a curing treatment to 60
A method for producing a thermal transfer receiving sheet, which comprises forming an image receiving layer having a water content of 0 to 9,000 ppm. 2. The thermal transfer receiving sheet according to claim 1, wherein the coating liquid further contains a polyisocyanate compound, and the dye-dyeable resin is cross-linked by the polyisocyanate compound by the drying and curing treatments. Production method.