JP4073852B2 - Thermal transfer image-receiving sheet and method for producing the same - Google Patents

Description

  The present invention relates to a thermal transfer image-receiving sheet that is used by being superimposed on a thermal transfer sheet, and a method for manufacturing the same.

  As a method of forming an image using thermal transfer, a thermal transfer sheet in which a sublimation dye as a recording material is supported on a base sheet such as paper or plastic film, and a sublimation dye receiving layer on one side of the paper or plastic film There is known a method of forming a full-color image by superimposing them on a thermal transfer image-receiving sheet provided with. Since this method uses a sublimation dye as a color material, the density gradation can be freely adjusted in dot units, and a full-color image as in the original can be expressed on the image receiving sheet. Since the image formed with the dye is very clear and excellent in transparency, it is excellent in reproducibility of intermediate colors and gradations, and a high-quality image comparable to a silver salt photograph can be formed.

  In order to form a high-quality print image on an image receiving sheet at a high speed in a sublimation type thermal transfer printer, a dye-dyeing resin (resin that easily dyes) is mainly used on the base of the image receiving sheet. It is desirable to provide a dye-receiving layer as a component. However, when coated paper or art paper is used as the base material of the image-receiving sheet, the thermal conductivity of these materials is relatively high, so that the dye is received in the receiving layer. Sensitivity is low.

  Therefore, a biaxially stretched foam film having a thermoplastic resin such as polyolefin as a main component and having voids inside may be used as the base material of the image receiving sheet. An image-receiving sheet using such a film as a base material has a uniform thickness, flexibility, and low thermal conductivity compared to paper made of cellulose fibers, so that a uniform and high-density image can be obtained. There is an advantage. However, when a biaxially stretched film is used as the substrate of the image receiving sheet, the residual stress during stretching is relaxed by heat during printing, and the film contracts in the stretching direction. As a result, the image receiving sheet may be curled or wrinkled, and a trouble such as a paper jam may occur when the image receiving sheet travels in the printer.

In order to remedy these drawbacks, a laminate sheet in which a biaxially stretched foam film having voids is bonded to a core material having a relatively small thermal shrinkage rate or a core material having a large elastic modulus is used as a base material for the image receiving sheet. There is also an example to use. There is also a thermal transfer image-receiving sheet in which a non-foamed plastic film is superposed through an adhesive containing a foaming agent in the core, and the foaming agent is foamed in that state to make the adhesive layer have a porous structure (Patent Document 1). reference). A technique for forming a porous layer having both heat insulating properties and cushioning properties by applying a porous layer coating liquid in which hollow particles are mixed with a binder resin to a base sheet is also known (see Patent Document 2).
JP-A-6-239040 JP 2002-212890 A

  However, a biaxially stretched film having voids is highly stretchable, and it is difficult to control the tension during lamination, resulting in poor productivity. Manufacturing costs also increase significantly. Also, when a porous layer is formed by applying a porous layer coating solution to a paper substrate, depending on the material of the paper substrate and the type of binder resin, the moisture of the coating solution may penetrate the paper substrate and dry. Concavities and convexities are generated on the surface of the porous layer, and as a result, irregularities appear on the surface of the dye receiving layer, which may cause defects such as density unevenness and missing dots during image formation.

  Therefore, the present invention can avoid various production problems associated with the bonding of the foam film, and the moisture contained in the porous layer coating liquid does not have a risk of penetrating into the paper base material. It is an object of the present invention to provide a thermal transfer image receiving sheet capable of obtaining a high quality image and a method for producing the same.

  The thermal transfer image receiving sheet of the present invention is characterized by being a claim copy.

  According to this thermal transfer image-receiving sheet, a dye-receiving layer is provided on one surface side of a substrate film different from the paper substrate, and a porous layer is provided on the other surface side. Since water does not penetrate, or even if it penetrates, the penetration level is far less than the penetration to the paper substrate, so the unevenness of the substrate forming the porous layer is suppressed and the dye receiving layer is formed with high smoothness be able to. Also, since the porous layer provided on the substrate film and the paper substrate are bonded together via an adhesive layer, if the paper substrate is bonded after drying the porous layer coating liquid, There is no possibility of penetrating into the substrate, and the appearance of irregularities can be prevented regardless of the type of paper substrate, and the smoothness of the dye-receiving layer can be maintained high. Thereby, it is possible to obtain a high-quality image free from density unevenness and missing dots during image formation.

  A schematic cross-sectional configuration diagram of a thermal transfer image receiving sheet 1 according to an embodiment of the present invention is shown in FIG. 1A. A schematic cross-sectional configuration diagram of a thermal transfer image receiving sheet 1 according to an embodiment of the present invention is shown in FIG. 1A. The base film 2 is composed of an intermediate layer 4 and a dye receiving layer 5 on one surface side of the base film 2 and a porous layer 3 on the other surface side. The porous layer 3 is composed of high heat resistant particles and a binder resin. The high heat-resistant particle layer and the hollow particle layer composed of a hollow particle and a binder resin are composed of two layers, and the porous layer 3 is laminated on a paper substrate through seven adhesive layers.

  The base film 2 is preferably one that does not absorb or hardly absorbs moisture when the porous layer 3 is applied, and a plastic film is preferably used. As a plastic film used here, the film comprised, for example with various resin, such as PET film, polyethylene, a polypropylene, can be used. In order to reduce the influence of the physical properties of the base film 2 on the dye-receiving layer 5, the base film 2 is desirably as thin as possible. Preferably, the thickness of the base film 2 is 20 μm or less. When the thickness of the base film exceeds 20 μm, the influence of the physical properties of the base film cannot be ignored compared with the influence of the cushioning property and heat insulating property of the porous layer, and the image is caused by the non-uniformity of the base film. There is a risk of density unevenness during formation. The lower limit of the thickness of the base film is not particularly limited as long as the above required characteristics are satisfied. However, if it is too thin, moisture may permeate through the film when the porous layer 3 is applied, and the film may be obtained or manufactured. Due to the limitation, it becomes about 2.5 μm or more.

  The porous layer 3 includes two layers, a high heat resistant particle layer 31 made of high heat resistant particles and a binder resin, and a hollow particle layer 32 made of hollow particles and a binder resin. By providing the high heat-resistant particle layer in this way, there are problems that occur when only the hollow particle layer is provided, that is, the problem that the density of the three-color mixed color is lower than that of the single color, and there is a dent in the three-color mixed color print portion. And the problem of embossing in the image can be avoided. In FIG. 1A, the high heat resistant particle layer 31 and the hollow particle layer 32 are sequentially formed on the base film, but the formation order of the high heat resistant particle layer 31 and the hollow particle layer 32 may be reversed. In order to avoid embossing of the image, it is effective to provide a heat-resistant particle layer at a position close to the thermal head. From this viewpoint, the high heat-resistant particle layer 31 and the hollow particle layer 32 are formed in this order on the base film. It is preferable.

  The high heat resistant particle layer 31 is formed by binding at least high heat resistant particles to a binder resin. Specifically, a coating solution in which a binder resin and high heat-resistant particles are dissolved and dispersed in a solvent is applied to the lower surface side of the base film 2 and dried, so that the film thickness after drying is 4 It is formed to be -12 μm, preferably 5-10 μm. However, it is preferable to form so that the total film thickness (film thickness of a porous layer) with the hollow particle layer mentioned later may become the range of 5-40 micrometers. If the thickness is less than 5 μm, sufficient heat insulating properties and cushioning properties may not be obtained. On the other hand, if it exceeds 40 μm, the heat insulating properties may reach saturation, resulting in cost waste.

  The high heat resistant particles have a heat resistant temperature of 200 ° C. or higher, preferably 300 ° C. or higher, and have heat insulation properties. The heat resistant temperature of the particles depends on the constituent material of the particles, production conditions, availability, etc., but it is preferably as high as possible. From this viewpoint, the upper limit of the heat resistant temperature of the particles is not particularly limited. The heat-resistant temperature of the particles is the maximum temperature at which the particles can withstand without being destroyed or crushed by heat. In the present invention, the heat-resistant temperature is a value measured by a thermal stress strain measuring device (TMA) (manufactured by Seiko Electronics Co., Ltd.). It is only necessary to represent and have the above heat-resistant temperature. The volume average particle diameter of the high heat-resistant particles is 0.1 to 10 μm, preferably 0.1 to 5 μm. If it is larger than 10 μm, particles will be lost in the image, and if it is smaller than 0.1 μm, a sufficient porosity cannot be secured and the cost will be increased.

  The high heat resistant particles may be made of resin or glass. In the case of resin, the kind is not particularly limited, but for example, styrene resin, (meth) acrylic resin, styrene- (meth) acrylic resin, phenolic resin, fluorine resin, polyamide resin, polyimide Resin, polycarbonate resin, polyether resin, and other various known resins.

  The high heat resistant particles may be hollow particles. Such a high heat-resistant hollow particle is, for example, a hollow particle in which the degree of crosslinking of the resin constituting the hollow particle is further increased to increase the heat resistance, and has the heat resistance described above. The porosity of the high heat-resistant hollow particles may be smaller than the porosity of the hollow particles. Commercially available products are available as highly crosslinked styrene-acrylic hollow resin (SX-866; manufactured by JSR), silica-based hollow particles (Godball B-6C; manufactured by Suzuki Oil & Fats Co., Ltd.), and the like.

  The content ratio of the high heat-resistant particles in the high heat-resistant particle layer is preferably in the range of 70 to 90% by weight. If it is less than 70% by weight, sufficient heat resistance may not be obtained, and if it exceeds 90% by weight, the binding force may be insufficient and the porous layer may be peeled off from the substrate film.

  As the binder resin used for the high heat-resistant particle layer, a polyester resin, a urethane resin, a vinyl acetate resin, an acrylic resin and a copolymer thereof, or a resin blended with them is dissolved in water, dispersed, or made into an emulsion. And water-soluble resins such as polyvinyl alcohol, carboxymethylcellulose, starch and sodium polyacrylate are used. When polyester is used for the base film, it is preferable to use a polyester resin as the porous layer binder from the viewpoint of adhesion between the base film and the porous layer. For example, a polyester resin (Vylonal MD-1480; manufactured by Toyobo Co., Ltd.) can be used. Water-soluble resins such as polyvinyl alcohol, carboxymethyl cellulose, and sodium polyacrylate have a high viscosity and are excellent in water retention, and thus are preferable in preventing moisture from penetrating into the base film 2.

  The hollow particle layer 32 is formed by binding at least hollow particles to a binder resin. Specifically, in the case of the configuration of FIG. 1A, a coating liquid in which a binder resin and hollow particles are dissolved and dispersed in a solvent is applied to the lower surface side of the high heat resistant particle layer 31 and dried. The film thickness after drying is 5 to 40 μm, preferably 10 to 20 μm. However, as described above, the total film thickness (the film thickness of the porous layer) with the high heat-resistant particle layer is formed in the range of 5 to 40 μm.

The hollow particles used in the hollow particle layer 32 may be either expanded particles or non-expanded particles. For example, organic hollow particles such as crosslinked styrene-acryl, inorganic hollow glass bodies, and the like can be used as the hollow particles. When foamed particles are used, either closed foaming or continuous foaming may be used. The volume average particle diameter of the hollow particles is 0.1 to 10 μm, preferably 0.1 to 5 μm.
If it is larger than 10 μm, particles will be lost in the image, and if it is smaller than 0.1 μm, a sufficient porosity cannot be secured and the cost will be increased. The void ratio of the hollow particles is preferably 50% or more. If the porosity is less than 50%, the porous layer 3 may not be able to be provided with sufficient heat insulation and cushioning properties. Moreover, the content ratio of the hollow particles in the hollow particle layer 32 is preferably in the range of 70 to 90% by weight. If it is less than 70% by weight, sufficient heat insulating properties and cushioning properties may not be obtained, and if it exceeds 90% by weight, the binding force may be insufficient and the hollow particle layer may be peeled off.

  As the binder resin used for the hollow particle layer, the same binder resin used for the high heat-resistant particle layer can be similarly used.

  The high heat-resistant particle layer and the hollow particle layer constituting the porous layer can be formed by a general coating method such as gravure coating, gravure reverse coating, comma coating, die coating, and lip coating.

  In the above, the case where the porous layer is composed of two layers of the high heat resistant particle layer and the hollow particle layer has been described. However, the structure of the high heat resistant particle layer / hollow particle layer / three high heat resistant particle layers, the high heat resistant particle layer / general purpose resin A multilayer structure such as a three-layer structure of layers / hollow particle layers may be employed. Thus, the above-mentioned high heat-resistant particle layer and hollow particle layer can also be applied in the case of a multilayer structure of three or more layers.

  The intermediate layer 4 refers to all the layers interposed between the base film 2 and the dye receiving layer 5. The intermediate layer 4 may have either a single layer structure or a multilayer structure. The intermediate layer 4 may be provided as necessary and may be omitted. The intermediate layer may be the same as the porous layer constituting binder resin.

For the intermediate layer 4, calcium carbonate, talc, kaolin, titanium oxide, zinc oxide, etc. are known as inorganic pigments in order to impart concealability and whiteness, and to adjust the overall texture of the thermal transfer image-receiving sheet 1. Inorganic pigments and fluorescent brighteners may be included. Their blending ratio is preferably 10 to 200 parts by weight with respect to 100 parts by weight of the resin solid content ratio. If the amount is less than 10 parts by weight, the effect is not sufficiently exhibited. If the amount exceeds 200 parts by weight, the dispersion stability is insufficient and the performance of the resin may not be obtained. The intermediate layer is formed to a thickness of about 0.5 to 5 g / m ² depending on the purpose of formation. The formation may be performed by a general coating method such as gravure coating, gravure reverse coating, comma coating, die coating, and lip coating.

  The dye receiving layer 5 is constituted by adding various additives such as a release agent to a varnish mainly composed of a resin that can be easily dyed with a dye as necessary. Examples of resins that can be easily dyed with dyes include polyolefin resins such as polypropylene, halogenated resins such as polyvinyl chloride resin and polyvinylidene chloride, vinyl resins such as polyvinyl acetate and polyacrylate, and copolymers thereof, polyethylene terephthalate Polyester resins such as polybutylene terephthalate, polystyrene resins, polyamide resins, copolymers of olefins such as ethylene and propylene and other vinyl monomers, ionomers, cellulose derivatives alone, or mixtures thereof can be used. Among these, polyester resins and vinyl resins are preferable.

  In the dye receiving layer 5, a release agent can also be blended to prevent thermal fusion with the thermal transfer sheet during image formation. As the mold release agent, silicone oil and phosphoric ester plasticizer fluorine-based compound can be used, and silicone oil is particularly preferably used. As the silicone oil, modified silicones such as epoxy modification, alkyl modification, amino modification, fluorine modification, phenyl modification, and epoxy / polyether modification are preferably used. Among them, a reaction product with vinyl-modified silicone oil and hydrogen-modified silicone oil is preferable. The addition amount (total amount) of the release agent may be about 0.2 to 30 parts by weight with respect to 100 parts by weight of the resin forming the dye receiving layer 5.

The dye receiving layer 5 is formed by a general coating method such as roll coating, bar coating, gravure coating, or gravure reverse coating. The coating amount of the dye receiving layer 5 is about 0.5 to 10 g / m ² .

The paper base 6 is used to give the entire thermal transfer image-receiving sheet 1 a texture and rigidity comparable to a silver salt photograph. As the paper substrate 6, for example, high-quality paper or art paper having a basis weight of 78 to 400 g / m ² , preferably 150 to 300 g / m ² can be used. The thickness of the paper substrate 6 is preferably in the range of 40 to 300 μm, more preferably in the range of 60 to 200 μm. In order to give the thermal transfer image-receiving sheet 1 a texture equivalent to that of silver halide photographic printing paper, the overall thickness of the thermal transfer image-receiving sheet 1 is preferably set in the range of 150 to 250 μm.

The adhesive layer 7 may be of any type as long as it can join the paper substrate 6 and the porous layer 3, but typically, urethane, polyolefin, polyester, acrylic or epoxy adhesive resin is used. be able to. In addition, as a method of adhering the porous layer 3 and the paper base material 6, a so-called EC laminating method in which the porous layer 3 and the paper base material 6 are bonded together while extruding the resin constituting the adhesive layer and sandwiching the extruded resin. The porous layer 3 and the paper base material 6 can be bonded together while forming the adhesive layer 7 by using it. Examples of the extrusion resin used in the EC lamination method include polyolefin-based general-purpose resins. The adhesive layer 7 is usually formed in a range of about 10 g / m ² .

  As shown in FIG. 2, by providing a resin coat layer 8 on the lower surface of the paper substrate 6, the paper substrate 6 is given moisture retention to prevent curling, or the thermal transfer image receiving sheet 1 is conveyed by a printer. You may provide the slipperiness which reduces the frictional resistance at the time. In order to achieve the purpose of imparting moisture retention, a resin having a wheel control switch effect such as polyvinyl alcohol or polyethylene glycol can be used as the material of the resin coat layer 8. In order to impart lubricity, a resin in which an inorganic or organic filler is dispersed may be used as the material of the resin coat layer 8. Further, a lubricant such as silicone or a release agent may be added to the resin coat layer 8.

  FIG. 1B shows a schematic cross-sectional configuration diagram showing a state during the formation of the thermal transfer image receiving sheet 1 of the present invention. As shown in FIG. 1B, the thermal transfer image-receiving sheet 1 comprises a laminate by sequentially forming a porous layer 3 on the lower surface side of the base film 2 and optionally an intermediate layer 4 and a dye-receiving layer 5 on the upper surface side, A paper substrate 6 is bonded to the lower surface of the porous layer 3 of the laminate through an adhesive layer 7. In the thermal transfer image receiving sheet of the present invention, the order in which the dye receiving layer and the porous layer are formed on the base film is not particularly limited.

  According to the thermal transfer image-receiving sheet and the method for producing the same of the present invention, a dye-receiving layer is provided on one surface side of a substrate film different from the paper substrate, and a porous layer is provided on the other surface side. Even if moisture does not penetrate into the base film during coating, or even if it penetrates, the degree of penetration is far less than the penetration into the paper base, so the unevenness of the base that forms the porous layer is suppressed, and the dye receiving layer Can be formed with high smoothness. In addition, if the paper base material is pasted after drying the coating liquid for the porous layer, there is no risk of moisture penetrating into the paper base material, preventing the appearance of irregularities regardless of the type of paper base material and accepting the dye. The smoothness of the layer can be kept high. Thereby, it is possible to obtain a high-quality image free from density unevenness and missing dots during image formation.

The present invention will be described more specifically with reference to the following examples. In this example, “parts” or “%” is based on mass (parts by weight,% by weight) unless otherwise specified.
Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
Polyester film 4 [mu] m; intermediate layer, the receiving layer by a gravure coating, respectively after drying 1.0 g ^/ m 2 having the following composition on one surface of the (Lumirror 4F56 manufactured by Toray Industries (Ltd.)), 4.0g / ^{m 2} Coating and drying were performed to form an intermediate layer and a receiving layer.
・ Intermediate layer Polyster resin (Vylonal MD-1480; manufactured by Toyobo Co., Ltd.) 20 parts by weight Water / IPA = 1/1 (IPA = Isopropyl alcohol) 100 parts by weight Receptor layer Vinyl chloride-vinyl acetate copolymer ( # 1000A; manufactured by Denki Kagaku Kogyo Co., Ltd.) 120 parts by weight Epoxy-modified silicone (X22-3000T; manufactured by Shin-Etsu Chemical Co., Ltd.) 12 parts by weight Phenyl-modified silicone (X24-510; manufactured by Shin-Etsu Chemical Co., Ltd.) 6 Parts by weight methyl ethyl ketone / toluene = 8/2 50 parts by weight

A high heat resistant particle layer and a hollow particle layer having the following composition are coated on the surface opposite to the receiving layer of the polyester film by gravure coating, dried and dried so that the thickness after drying is 8 μm and 15 μm, respectively. Formed.
・ High heat resistant particle layer 1
Highly crosslinked styrene-acrylic hollow particles (SX-866; manufactured by JSR) 80 parts by weight (volume average particle size = 0.3 μm, hollow rate 30%, heat-resistant temperature 300 to 330 ° C.)
Polyester resin (Vylonal MD-1480; manufactured by Toyobo Co., Ltd.) 20 parts by weight Water 400 parts by weight, hollow particle layer 1
Acrylic hollow particles (Ropeke HP-1055; manufactured by Rohm and Harm) 80 parts by weight (volume average particle diameter = 1 μm, hollow ratio 50%)
Polyester resin (Vylonal MD-1480; manufactured by Toyobo Co., Ltd.) 20 parts by weight Water 400 parts by weight

Next, EC lamination is performed on the porous layer side of the coated polyester film and a coated paper (base sheet) having a basis weight of 158 g / m ² with an extrusion resin having the following composition by a T-die method to form a thermal transfer image-receiving sheet 1. Obtained. In addition, the thickness of the adhesive bond layer by extrusion resin is 10 g / m < ² > (solid content).
Extruded resin Polyethylene resin (Sumikasen 10P; manufactured by Sumitomo Mitsui Polyolefin Co., Ltd.)

(Example 2)
A thermal transfer image receiving sheet 2 was obtained in the same manner as in Example 1 except that the thickness of the high heat resistant particle layer 1 in Example 1 was changed to 5 μm.

(Example 3)
A thermal transfer image receiving sheet 3 was obtained in the same manner as in Example 1 except that the thickness of the high heat resistant particle layer 1 in Example 1 was changed to 10 μm.

Example 4
A thermal transfer image receiving sheet 4 was obtained in the same manner as in Example 1 except that the high heat resistant particle layer of Example 1 was changed to the high heat resistant particle layer 2 having the following composition.
・ High heat resistant particle layer 2
Acrylic hollow particles (Ropeke HP-1055; manufactured by Rohm and Harm) 10 parts by weight Cross-linked acrylic particles (MX150; manufactured by Soken Chemical Co., Ltd.) 70 parts by weight (volume average particle size = 1.5 μm, no hollowness, heat resistant temperature 200 ° C. )
Polyester resin (Vylonal MD-1480; manufactured by Toyobo Co., Ltd.) 20 parts by weight Water 400 parts by weight

(Example 5)
A thermal transfer image-receiving sheet 5 was obtained in the same manner as in Example 1 except that the porous layer prepared in Example 1 had a three-layer structure of high heat-resistant particle layer 1 / hollow particle layer / high heat-resistant particle layer 1.

(Comparative Example 1)
A thermal transfer image receiving sheet 6 was obtained in the same manner as in Example 1 except that the porous layer of Example 1 was composed only of a hollow particle layer having a layer thickness of 23 μm.

(Comparative Example 2)
A thermal transfer image-receiving sheet 7 was obtained in the same manner as in Example 1 except that the porous layer of Example 1 was composed of only a high heat-resistant particle layer having a layer thickness of 23 μm.

(Comparative Example 3)
A thermal transfer image-receiving sheet 8 was obtained in the same manner as in Example 1 except that the porous layer of Example 1 was composed only of the high heat-resistant particle layer having the following composition having a layer thickness of 23 μm.
・ High heat-resistant particle layer 3
Cross-linked acrylic particles (MX150; manufactured by Soken Chemical Co., Ltd.) 80 parts by weight Polyester resin (Vylonal MD-1480; manufactured by Toyobo Co., Ltd.) 20 parts by weight Water 400 parts by weight

<Evaluation>
Next, the thermal transfer image receiving sheets of Examples and Comparative Examples were evaluated as follows.
<Appearance evaluation of printed matter>
Using Canon sublimation transfer printer CP-100 and transfer film for CP-100, actual images were printed using the thermal transfer image-receiving sheets of Examples and Comparative Examples, and the appearance of the printed matter was evaluated.
○: No depression in the image.
X: The image has a dent. Especially the black print part.
The evaluation results are summarized in Table 1 below.

<Print density evaluation>
Thermal Transfer Recording As a thermal transfer film, a transfer film UPC-740 for sublimation transfer printer UP-D70A manufactured by Sony Corporation was used. Using the thermal transfer image-receiving sheets of the above examples and comparative examples, the dye layer and the dye-receiving layer surface are overlapped with each other, and Y, M, C, and a protective layer are arranged in the order of Y, M, C, and protective layer from the back surface of the thermal transfer film under the following conditions. Thermal transfer recording was performed.

A gradation image was formed by thermal transfer recording under the following conditions.
・ Thermal head: KYT-86-12MFW11 (manufactured by Kyocera Corporation)
-Heating element average resistance: 4412 (Ω)
・ Main scanning direction printing density: 300dpi
-Sub-scanning direction printing density: 300 dpi
・ Applied power: 0.136 (w / dot)
・ One line cycle: 6 (msec.)
・ Printing start temperature: 30 (℃)
-Print size: 100mm x 150mm
・ Gradation printing: Using a multi-pulse test printer that can vary the number of divided pulses from 0 to 255 with a pulse length that equally divides one line period into 256 within one line period, the duty of each divided pulse The ratio is fixed at 40%, and the number of pulses per line cycle is increased from 0 to 255 in increments of 17 from 0 to 255, such as 0 for 1 step, 17 for 3 steps, 34 for 3 steps, etc. Thus, 16 gradations from 1 step to 16 steps were controlled.
・ Protective layer transfer: Using a multi-pulse test printer that can vary the number of divided pulses from 0 to 255 in a line cycle with a pulse length obtained by equally dividing one line cycle into 256, the duty of each divided pulse The ratio was fixed at 50%, the number of pulses per line period was fixed at 210, solid printing was performed, and the protective layer was transferred to the entire printed surface.

The maximum reflection density of the printed matter was measured with a visual filter using an optical reflection densitometer (Macbeth RD-918: manufactured by Macbeth).
○: Maximum reflection density 2.0 or more ×: Maximum reflection density less than 2.0

  The overall evaluation in Table 1 was evaluated as “◯” when both the print density and the printed product appearance were “◯”, and “X” when either one was “X”.

(The invention's effect)
The thermal transfer image receiving sheet of the present invention can form a high-quality image without density unevenness, missing dots, and embossing.
According to the method for producing a thermal transfer image receiving sheet of the present invention, the dye receiving layer can be formed with high smoothness regardless of the type of paper substrate.

FIG. 3 is a schematic cross-sectional configuration diagram of the thermal transfer image receiving sheet of the present invention. FIG. 3 is a schematic cross-sectional configuration diagram of the thermal transfer image receiving sheet of the present invention. The typical cross-section block diagram showing the state in the middle of formation of the thermal transfer image receiving sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal transfer image receiving sheet 2 Base film 3 Porous layer 4 Intermediate layer 5 Dye receiving layer 6 Paper base material 7 Adhesive layer 8 Resin coat layer 31 High heat-resistant particle layer 32 Hollow particle layer

Claims (4)

At least a base film, a dye receiving layer on one side of the base film, and a porous layer on the other side, and the porous layer is laminated on a paper base via an adhesive layer A thermal transfer image-receiving sheet, wherein the porous layer comprises at least two layers of a high heat-resistant particle layer comprising a high heat-resistant particle having a heat-resistant temperature of 200 ° C. or higher and a binder resin, and a hollow particle layer comprising a hollow particle and a binder resin. Characteristic thermal transfer image receiving sheet.   The thermal transfer image receiving sheet according to claim 1, wherein the high heat resistant particles are resin particles.   The thermal transfer image receiving sheet according to claim 1, wherein the high heat resistant particles are high heat resistant hollow particles. A method for producing a thermal transfer image-receiving sheet according to any one of claims 1 to 3,
A thermal transfer image-receiving sheet comprising a dye-receiving layer on one side of a base film and a porous layer on the other side, and then bonding the porous layer and a paper base through an adhesive layer Manufacturing method.

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