JPH0966679A - Melt transfer type recording sheet and its forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a melt transfer type recording sheet of superior durabilities such as resistance to scuffing, resistance to stains, light fastness and the like of an image by providing a porous ink acceptive layer of a specified average void diameter composed of a porous resin containing film on which a thermal transfer image is formed and the like on a sheet-like substrate. SOLUTION: This melt transfer type recording sheet is formed by providing a porous ink acceptive layer 6 composed of a porous resin film with the surface average void diameter of 0.5-30μm a thermal transfer image 7, a bonding layer 4 and a transparent protective layer 2 on a substrate 5. The porous ink acceptive layer 6 provided with a number of microfine foams formed by applying the mechanical agitation to a resin containing solution and also with the expansion ratio of a foam containing resin containing solution (the ratio between the volume after foaming and the volume before foaming based on the comparison of stock solution of given weight) of 1-10 times is suitable. An ink image recording of good reproducibility, tone reproducibility and the like and high recoring density can be provided when the above-said recording sheet is used in a thermal color printer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melt transfer type recording sheet and a method for forming the same. More specifically, when the present invention is used in a fusion transfer type thermal transfer printer using a thermal head, a print ink image having high recording density and excellent gradation reproducibility and dot reproducibility can be obtained. And by laminating a transparent protective layer, you can freely add gloss or matteness to the image area,
The present invention also relates to a melt transfer type recording sheet excellent in durability such as scratch resistance, stain resistance and light resistance of an image and storability, and a method for forming the same.

[0002]

2. Description of the Related Art A thermal fusion transfer recording method using a thermal transfer ink sheet and a thermal head is widely used in printers such as word processors and facsimiles because of its simple mechanism and easy maintenance. Along with this, there has been a demand for a recorded image having excellent gradation reproducibility with high accuracy and dot reproducibility in which the dot shape of ink is faithfully reproduced. Further, in recent years, it has come to be widely used as a simple printing method as an application, and images such as various characters, symbols, and facial photographs can be easily formed. , ID cards, commuter passes, prepaid cards, name cards, etc. Therefore, an excellent recorded image is desired, and since the commuter pass and the like are frequently used, abrasion resistance of the recorded image,
Durability such as stain resistance and light resistance and storage stability have come to be required.

Conventionally, as the image-receiving sheet for this thermal transfer recording system, a paper (high quality, coated paper) having a slightly higher smoothness than general high quality paper has been used. However, when a conventional paper is used in the heat-melt transfer method, the recording density may be decreased due to the low heat insulating property, and the dot reproducibility may be deteriorated due to insufficient cushioning property. Further, the ink, which has a small number of voids for absorbing the transferred ink, is reversely transferred to the ink ribbon, or the ink remarkably spreads on the receiving layer. Any of these causes a poor dot reproducibility. Therefore, satisfactory quality cannot be obtained for full-color thermal transfer images as described above.

As an attempt to solve the problem of high image quality (full color) of the recording, it has been proposed to provide an undercoat layer containing hollow particles on the support in order to improve the cushioning property of the image receiving sheet. (Japanese Patent Laid-Open No. 2-8
9690, JP-A-64-27996). However, with this method, although high cushioning properties and heat insulating properties can be obtained on the image receiving sheet, good dot reproducibility cannot be obtained because the voids that absorb ink are not sufficient.

Regarding the durability and storability of the recorded image quality, in the thermal transfer method using the melted ink, since the ink of the formed image contains soft wax as a main component, it easily peels off with a nail or the like. Therefore, under the present circumstances, it is not possible to satisfy the required performance such as abrasion resistance, stain resistance, light resistance, and the like of recorded images, and durability.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the drawbacks of the prior art, and has good dot reproducibility, gradation reproducibility and color sharpness even when used in a thermal transfer color printer, and ink of high recording density. Melt transfer type recording that provides image recording and can freely add glossiness or matteness to recorded images, and has excellent durability and storage stability such as scratch resistance, stain resistance, light resistance, etc. The present invention relates to a sheet and a method for forming the sheet.

[0007]

The melt transfer type recording sheet of the present invention comprises a sheet-like support and a porous ink-receiving layer formed on one surface of the sheet-like support and comprising a porous resin-containing film. And the average pore diameter of the surface of the porous ink-receiving layer is in the range of 0.5 to 30 μm, and a thermal transfer image is formed on the porous ink-receiving layer, and further on the thermal transfer image. It is characterized by having a transparent protective layer. In the melt transfer recording sheet of the present invention, the porous ink receiving layer has a large number of fine bubbles formed by subjecting the resin-containing liquid to mechanical agitation, and the foaming ratio (constant The ratio of the volume after foaming to the volume before foaming, which is compared with the undiluted solution of weight, is 1 to 1
It is preferably 0 times.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a thermal transfer image-receiving sheet having a porous ink receiving layer provided on one surface of a sheet-like support, wherein a thermal transfer image is formed on the porous ink receiving layer. It has a transparent protective layer on the thermal transfer image. When used in a thermal transfer color printer, the fused thermal transfer ink image-receiving sheet provided with a porous ink receiving layer has good dot reproducibility, gradation reproducibility, color sharpness, etc., and ink image recording with high recording density can be obtained. However, depending on the purpose of use, the scratch resistance of the image was insufficient. As a result of diligent studies on these, after forming a thermal transfer image on the receiving layer of the melt thermal transfer type ink image-receiving sheet provided with a porous ink receiving layer, a transparent protective layer is formed on the thermal transfer image to improve the image resistance of the image. It has become possible to obtain a melt transfer type recording sheet which is excellent not only in scratch resistance but also in durability such as stain resistance and light resistance and storage stability.

The mechanism of the molten ink thermal transfer method in the present invention is such that the thermally fusible ink layer on the surface of the substrate film and the receptor layer of the thermal transfer image-receiving sheet are overlapped with each other, and the image is heated from the back surface of the thermal transfer sheet. To form an image. Therefore, in order to improve the transferability of the molten ink, first, the heat insulating property and cushioning property of the receptive layer are required, and then, appropriate pores are required on the surface of the ink receptive layer as voids for receiving the molten ink. Becomes Therefore, it is considered that the structural properties, the heat insulating property, the physical properties such as the cushion of the porous ink receiving layer are involved in the development of the excellent molten ink transfer performance.

The ink receiving layer of the present invention has numerous pores. The size of the pores on the surface is important because the pore size has the absorbability of the molten ink by the capillary force. That is, when the molten ink is transferred,
In order to form a good image on the image-receiving sheet of the present invention, the average pore diameter of the surface of the ink-receiving layer is 0.5 to 30 μm.
In the range of 1.0 to 15 μm. The pore diameter is related to the ability to capture the molten ink due to the capillary phenomenon caused by its size. The smaller the pore, the greater the ability, but the fluidity of the molten ink is small, so 0.5 μm.
If it is less than the above range, the ink absorbing ability is lowered. On the other hand, 30
If it exceeds μm (the size becomes too large), the transfer ink will be buried in the pores, or the transfer between the ink ribbon and the surface of the porous ink-receptive layer will be hindered, resulting in defective transfer or uneven transfer. In addition, dot reproducibility is poor and a good image cannot be formed. The pore diameter on the surface of the porous ink receiving layer can be measured using an optical microscope or a scanning electron microscope photograph and an image analyzer.

In the present invention, preferably the dot reproducibility, gradation reproducibility and color sharpness are good by adjusting the open area ratio of the surface of the porous ink receiving layer to 10 to 60%. It is possible to obtain ink image recording with high recording density. By the way, if it is less than 10%, the heat insulating property and the space for receiving ink are insufficient. On the other hand, 6
If it exceeds 0%, the layer strength of the ink receiving layer at the time of thermal transfer recording becomes insufficient, and a good recorded image cannot be obtained. Here, the open area ratio is the ratio of the area of the holes to the entire coating film surface of the receiving layer.

The porous ink receiving layer of the present invention contains a resin or a resin and a pigment as main components. Such a porous ink-receiving layer is a liquid material containing a resin or a mixture of a resin and a pigment, which is subjected to mechanical agitation to disperse and contain a large number of fine air bubbles therein, It can be formed by coating on a support. The volume ratio of the bubble-containing liquid to the undiluted solution (hereinafter referred to as the expansion ratio) is preferably more than 1 time and 10 times or less, more preferably more than 1 time and 5 times or less. That is, the expansion ratio is a measure showing the bubble content rate in the liquid resin containing bubbles, and it means that when the expansion ratio becomes large, the heat insulating property of the receiving layer and the thickness of the resin film (wall) constituting the bubbles become thin. ing. By the way, if the expansion ratio exceeds 10 times, the resin film becomes thin,
The coating strength of the obtained ink receiving layer becomes insufficient.

The size of the pores depends on the composition of the resin-containing mixed liquid before the bubble formation / dispersion treatment, that is, the kind of materials, the mixing ratio, and the solid content concentration, that is, foaming, coating, and drying after receiving the porous ink. The amount remaining as a component directly related to the film thickness in the layer, or the foaming ratio, the coating method, etc.
Since it is often affected by various factors, it is necessary to set appropriate conditions. Further, the size of the pores on the surface of the ink receiving layer in the present invention is also related to the size of the bubbles in the bubble-containing resin liquid obtained by mechanical stirring, and generally, the smaller the bubbles in the resin-containing liquid are, Coating,
Since the pores on the surface of the ink receiving layer after drying are also small, the state of containing bubbles in the resin-containing mixed liquid is not particularly limited, but the same size as the surface of the porous ink receiving layer, that is, the average diameter is 0. It is preferable that fine bubbles of 5 to 30 μm are dispersed and mixed, and more preferably,
The average diameter is preferably in the range of 0.5 to 20 μm.
The size of the contained bubbles can be measured with an image analyzer by photographing a part of them with an optical microscope.

The resin used for forming the ink receiving layer in the present invention includes, for example, polyvinyl alcohol and its derivatives having various molecular weights and saponification degrees, starch, and starch derivatives (eg, oxidized starch and cationized starch). Modified starches), cellulose derivatives such as methoxycellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide-acrylic acid ester copolymer, acrylic acid amide-acrylic acid ester-methacrylic acid ester Copolymers, alkali salts of styrene-maleic anhydride copolymers, polyacrylamide and its derivatives, water-soluble resins such as polyethylene glycol, and polyvinyl acetate, polyurethane, polyurethane Len-butadiene copolymer, acrylonitrile-butadiene copolymer, polyacrylic acid ester, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-vinyl acetate copolymer, styrene-butadiene-acrylic copolymer, A water-dispersible resin such as acrylonitrile-butadiene copolymer, latex such as polyvinylidene chloride, etc., and glue, casein, soybean protein, gelatin, sodium alginate, etc. can be used, but not limited thereto. These resins can be used alone or in combination of two or more, if necessary.

In the present invention, examples of the pigment that can be contained in the porous ink receiving layer include zinc oxide, titanium oxide, calcium carbonate, silicic acid, silicate, clay, talc, mica, calcined clay, aluminum hydroxide, Inorganic pigments such as barium sulfate, lithopone, colloidal silica,
Use organic pigments such as true spheres such as polystyrene, polyethylene, polypropylene, epoxy resin, styrene-acryl copolymer, hollow, or processed into various shapes called plastic pigments, starch powder, cellulose powder, etc. However, the present invention is not limited to these. In addition, these pigments can be used alone or in combination of two or more, if necessary.

The compounding ratio of the above resin and pigment for obtaining a good melt thermal transfer image is as follows:
The amount of the pigment is preferably in the range of 0 to 900 parts by weight with respect to 00 parts by weight. If the number of parts of the pigment blended exceeds this range, the required coating film strength cannot be obtained, and problems such as peeling of the coating film during image formation occur, and good images are often not obtained.

In the liquid material containing the resin or the mixture of the resin and the pigment before the formation of bubbles, known viscosity adjusting agents, dispersants, dyes, waterproofing agents, lubricants, cross-linking agents, may be added, if necessary.
A plasticizer or the like can be added.

The coating amount of the porous ink receiving layer on the sheet-like support, that is, the coating amount, is 1 on one surface of the obtained support.
Dry weight per m ² is 2 to 40 g (2 to 40 g / m
^It is preferable to set it within the range of ² ). The coating amount is 2
When it is less than g / m ² , it is often difficult to sufficiently cover the surface roughness of the support, and the surface of the image receiving sheet cannot be properly smoothed, or the heat insulation property is insufficient. Compressive deformability may not be obtained. Meanwhile it is 40g
If it exceeds / m ² , the thickness of the porous ink-receiving layer becomes excessively large, and the bonding strength in the porous ink-receiving layer decreases, so that the porous ink-receiving layer peels off when an image is formed. Occasionally, a trouble such as occurrence may occur and a good image may not be formed. Therefore, it is natural that the application amount of the porous ink receiving layer should be properly adjusted as well as the resin containing liquid composition.

In the present invention, a method for containing and dispersing bubbles in a resin-containing liquid (hereinafter referred to as a foaming method) is, for example, a foaming machine for so-called confectionery having a stirring blade that rotates while making a planetary motion, generally an emulsion dispersion. For example, homogenizers such as homomixers, cowless dissolvers, etc., or mechanically agitating while continuously feeding a mixture of air and resin-containing liquid into a closed system into air into fine bubbles. dispersion,
Devices that can be mixed, such as Gaston County, Inc.
A continuous foaming machine such as Stoke Co. of the Netherlands can be used, but there is no particular strict limitation. In addition, because the capacity of the equipment for mechanical stirring is insufficient, the desired bubble-containing state cannot be obtained, or for the purpose of improving the stability of bubbles in the bubble-containing resin liquid, a foam stabilizer is used. Additives appropriately selected from materials having a wide range of surface-active properties, which are called foaming agents, may be added.

As such surfactants, higher fatty acids, modified products of higher fatty acids, alkali salts of higher fatty acids, etc.
In particular, it can be used because it has a high effect of enhancing the foamability of the resin-containing liquid and a high effect of improving the stability of the bubbles dispersed and contained therein. There is no particular strict limitation on the selection, but it is appropriate to avoid the use of a material that may significantly impede the fluidity of the resin-containing mixed solution or impair the coating workability. Further, the compounding ratio of the foam stabilizer or the foaming agent to the resin liquid or the mixed liquid of the resin liquid and the pigment is 100 parts by weight of the solid content of the resin liquid or the mixed liquid of the resin liquid and the pigment. On the other hand, the solid content is 0 to 30 parts by weight, preferably 1 to 20 parts by weight, and even if the amount is more than 30 parts by weight, the intended effect cannot be largely improved in many cases.

As a coating method for forming the porous ink receiving layer on the support, a Meyer bar method, a gravure roll method, a roll method, a reverse roll method, a blade method, a knife method, an air knife method, an extrusion method. , A casting method, or any other known method.

The sheet having the porous ink-receiving layer of the present invention can show a good melt thermal transfer image even when the resin solution containing bubbles is coated on a sheet-like support and dried, A machine calender composed of two or more rolls made of metal, or a super calender composed of a combination of a metal roll and a resin roll or a metal roll and a cotton roll is used for the porous ink receiving layer. A finishing treatment can be applied to further improve the smoothness of the surface. After coating, the surface of the porous ink receiving layer of the sheet in a semi-dried state or a dried state is brought into contact with a heated or non-heated cast drum having a mirror finish to improve its surface smoothness. May be. However, when the above smoothing treatment is applied under excessive pressure, the resin wall surrounding the bubbles in the porous ink receiving layer is destroyed, the ink receiving layer is densified, and the heat insulating property and cushioning property are deteriorated. Since the pores on the surface of the ink receiving layer are deformed or destroyed, the excellent molten ink transfer performance of the porous ink receiving layer may not be obtained. Therefore, it is necessary to thoroughly consider the processing conditions in the smooth finishing process.

As the sheet-like support used in the present invention, papers containing cellulose as a main component, coated papers, laminated papers and the like, and cloths such as woven cloths and non-woven cloths can be used. is there. Further, plastic films such as polyolefin, methacrylate and cellulose acetate, synthetic paper made of polyolefin and pigment, and porous synthetic resin film such as foamed polyethylene terephthalate film and foamed polypropylene film can be used.

Further, a resin solution containing bubbles may be coated on the above-mentioned sheet-like support, and a curl prevention layer and an antistatic layer may be coated or laminated on the back surface. In this case, it is possible to individually form on the back surface of the support to obtain the desired performance, but it is possible to simplify the manufacturing process, reduce the manufacturing cost, or the desired functional level, etc. By properly selecting the method, it is possible to achieve a purpose by forming a single layer. That is, it is possible to impart trouble prevention performance such as curling prevention and antistatic prevention with a single layer. Therefore, there is no limitation on the number of layers formed on the back surface of the sheet-shaped support.

In the thermal transfer recording method of the present invention, a thermal transfer ink sheet and a melt transfer type ink image receiving sheet are used to form a thermal transfer image on the ink receiving layer, and then a transparent protective layer is formed on the thermal transfer image. It is characterized by that. Examples of the resin used for the transparent protective layer include polyolefin resins such as polyethylene and polypropylene, acrylic resins, acrylic-vinyl chloride-vinyl acetate copolymer resins, chlorinated rubber, acrylic acrylic-chlorinated rubber resins, vinyl chloride-vinyl acetate copolymers. Resins, UV curable or electron beam curable resins, etc. may be mentioned. The resin for the transparent protective layer, for example, is used by forming a film on a base film,
The thickness is preferably about 0.5 to 10 μm, and transfer can be performed by heating or the like. Further, by adding additives such as an ultraviolet absorber, an antioxidant, and / or a fluorescent brightening agent to the resin, the light resistance, weather resistance, whiteness, etc. of the image to be coated can be improved. .
Further, in order to improve scratch resistance and printability, waxes and fine particles (polyethylene powder, micro silica, etc.) may be contained. It is of course possible to directly attach the film made of the resin as described above to the recording sheet after the thermal transfer image formation, and a film having a glossy surface or a matte surface can be appropriately selected.

In forming the transparent protective layer on the thermal transfer image, the thermal head of the thermal printer used for thermal transfer recording may be used, or a generally known laminator, a thermal roll, an iron, etc., or a coating method may be used. It is not particularly limited. Among these, the method of using the thermal head is simple and highly practical. In this case, the base film coated with the resin of the transparent protective layer and the thermal ink sheet may be substantially integrated.

[0027]

EXAMPLES The present invention will be more specifically described by the following examples.
explain. However, the present invention is limited by these
is not. In addition, "part" in Examples and Comparative Examples and
Unless otherwise specified, “%” means “part by weight of solid content” and
And "% by weight". Example 1 [Preparation of ink image-receiving sheet] A resin having the composition shown below.
Mix the fat mixture (solid content 30%) with a stirrer (trademark: Ken).
Mix Aiko PRO, manufactured by Aikosha Seisakusho)
Stir at a stirring speed of 490 rpm for 15 minutes to apply foaming treatment.
Was. The expansion ratio was 3.0 times.Resin mixture composition Styrene-butadiene latex (trademark: JSR0619, manufactured by Japan Synthetic Rubber) 100 parts Stearic acid-based foam stabilizer (trademark: SN foam 200, manufactured by San Nopco) 5 parts Carboxymethyl cellulose (trademark: serogen AG gum, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 10 Part Immediately after foaming the above resin mixture containing bubbles
/ M²Using an applicator bar on the surface of wood free paper
Coating amount after drying is 10g / m²And dry it
Dry to form an ink receiving layer and make an ink receiving sheet.
Made. Open area ratio of ink receiving layer surface is 40%, average
The pore diameter was 3.5 μm. [Preparation of thermal transfer sheet for transparent protective layer] As a base film
Polyethylene terephthalate film (trademark: SP
ET, manufactured by Toyobo, thickness 10 μm) and its back side
Acrylic resin (trademark: TP-64
(Manufactured by Dainippon Ink and Chemicals) 0.5 g / m², Transparent protective layer
Acrylic resin (trademark: BR-53, Mitsubishi
Made by Yeon) 3.0 g / m ², And for heat-sensitive adhesive layers
Vinyl chloride-vinyl acetate copolymer (trademark: Denka 100
0A, manufactured by Denki Kagaku) 0.5 g / m²Sequentially coated and dried
Then, a thermal transfer sheet for a transparent protective layer was produced. [Melt Transfer Recording and Formation of Transparent Protective Layer] The above ink
The image receiving sheet and the thermal transfer ink sheet are
Layer and ink receiving layer surface facing each other
Color printer (trademark: Trueprint 220
0, made by Victor Company of Japan, this printer is for sublimation transfer,
The ink has been modified to enable melt transfer recording).
The image was subjected to melt transfer recording to prepare a thermal transfer recording sheet.
Further, the heat for the transparent protective layer is formed on the image of the above-mentioned thermal transfer recording sheet.
The transparent protective layer of the transfer sheet is placed facing the resin side and overlapped.
The same as the thermal head used for recording, the base film side
Heat it up more and stack the transparent protective layer on the image to make it transparent.
A thermal transfer recording sheet having a protective layer on the image was obtained.

Example 2 Transparent protection was carried out in the same manner as in Example 1 except that a resin mixture having the following composition (solids concentration 40%, foaming ratio 3.0 times) was used in the formation of the ink receiving layer. A thermal transfer recording sheet having a layer was obtained. However, the open area ratio of the ink receiving layer surface was 20%, and the average pore diameter was 10 μm. Resin mixture liquid composition Styrene-butadiene latex (Trademark: JSR0692, made by Japan Synthetic Rubber) 100 parts Kaolinite clay (Trademark: HT clay, made by Engelhard) 100 parts Stearic acid type foam stabilizer (Trademark: SN foam 200, made by San Nopco) ) 10 copies

Example 3 Transparent protection was carried out in the same manner as in Example 1 except that a resin mixture having the following composition (solids concentration 40%, foaming ratio 5.0 times) was used in the formation of the ink receiving layer. A thermal transfer recording sheet having a layer was obtained. However, the open area ratio of the ink receiving layer surface was 50%, and the average pore diameter was 1.0 μm. Resin mixture liquid composition Aqueous polyurethane resin (Trademark: ADEKA BON TITER, Asahi Denka Kogyo) 100 parts Kaolinite clay (Trademark: HT clay, Engelhard) 100 parts Stearic acid foam stabilizer (Trademark: SN foam 200, San Nopco) 10 parts carboxymethyl cellulose (trademark: serogen AG gum, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 10 parts

Example 4 An ink image-receiving sheet was prepared in the same manner as in Example 1 and an ink image was melt-transfer recorded to obtain a thermal transfer recording sheet.
Next, on the ink image surface of this recording sheet, a biaxially stretched polypropylene film (thickness 10 μm) subjected to a mat super treatment is laminated with a synthetic rubber adhesive and laminated to provide a thermal transfer having a transparent protective layer on the matte surface. A mold recording sheet was obtained.

Comparative Example 1 An ink image-receiving sheet was prepared in the same manner as in Example 1, and the ink image was melt-transfer recorded to obtain a thermal transfer recording sheet.
However, the lamination of the transparent protective layer was omitted.

Comparative Example 2 An ink image-receiving sheet was prepared in the same manner as in Example 2, and the ink image was melt-transfer recorded to obtain a thermal transfer recording sheet.
However, the lamination of the transparent protective layer was omitted.

Comparative Example 3 An ink image-receiving sheet was prepared in the same manner as in Example 3, and the ink image was melt-transfer recorded to obtain a thermal transfer recording sheet.
However, the lamination of the transparent protective layer was omitted.

Comparative Example 4 A thermal transfer recording sheet was obtained in the same manner as in Example 1 except that the resin mixture was not foamed in the formation of the ink receiving layer.

Comparative Example 5 An ink image-receiving sheet was prepared in the same manner as in Comparative Example 4, and the ink image was melt-transfer recorded to obtain a thermal transfer type recording sheet.
However, the lamination of the transparent protective layer was omitted.

Quality Evaluation Method and Measurement Method In each Example and Comparative Example, the transfer ink image was evaluated and the open area ratio and the pore diameter were measured by the following methods, and the results are shown in Table 1. Show. [Evaluation of Image Quality] (1) Ink image formed with 17 gradations (black monochromatic image)
About the Macbeth reflection densitometer (trademark: RD-91
(4, manufactured by Macbeth) was used to measure the reflection density for each applied energy, and the maximum reflection density and gradation reproducibility were evaluated. Gradation reproducibility was evaluated in four grades of ⊚, ∘, Δ, and × in the order of good reproduction. (2) Dot reproducibility is four levels of ◎, ○, △, × in order from the one that is reproduced well as the gradation reproducibility by observing the ink dots transferred from the ink ribbon to the image receiving layer. It was evaluated by. (3) The image glossiness was evaluated by visually observing the image glossiness. The glossiness was evaluated in 3 grades in the order of gloss, dull and mat. (4) Evaluation method of image fastness (scratch resistance) The curved surface of the Zemclip is pressed against the image portion and rubbed 50 times,
The peeling of the recording portion was visually evaluated. Evaluation was made in four grades of ⊚, ◯, Δ, and × in order from the one without peeling.

[Measurement method of open area ratio and pore diameter]
The open area ratio and the pore diameter of the surface of the porous ink receiving layer can be measured by using a scanning electron microscope or an optical microscope.
After taking a picture of the surface of the receptive layer, accurately draw the outline of the pores on the surface with a black pen etc. on a transparent film, and further, drum scanner (trademark: 2605 type drum scan densitometer, Abe Design Co., Ltd.) Information of the pores was optically read by using an image analyzer (trademark: Luzex III, manufactured by Nireco Co., Ltd.). Since the shape of the pores formed on the surface of the porous ink receiving layer is not necessarily a perfect circle, the pore diameter is determined based on the area within the contour of the pores obtained by the image analysis device, and the equivalent circle diameter. Converted and displayed.

[0038]

[Table 1]

[0039]

INDUSTRIAL APPLICABILITY The present invention provides a print ink image having high recording density and excellent gradation reproducibility and dot reproducibility when used in a fusion transfer type thermal transfer printer using a thermal head. And by laminating a transparent protective layer, you can freely add gloss or matteness to the image area,
Further, the present invention relates to a melt transfer type recording sheet excellent in durability such as scratch resistance, stain resistance, and light resistance of an image and storability, and a method for forming the same, which greatly contributes to the industrial world.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing the constitution of one embodiment of a thermal transfer sheet for transparent protective layer of the present invention.

FIG. 2 is an explanatory cross-sectional view showing the constitution of one embodiment of the melt transfer type recording sheet of the present invention.

[Explanation of symbols]

 1. Base film 2. Transparent protective layer 3. Release layer 4. Adhesive layer 5. Sheet-like support 6. Porous ink receiving layer 7. Thermal transfer image 8. Image receiving sheet layer

Claims (3)

[Claims] 1. A sheet-like support, and a porous ink-receiving layer formed on one surface of the sheet-like support and comprising a porous resin-containing film, wherein the surface of the porous ink-receiving layer is Melt transfer recording characterized in that the average pore diameter is in the range of 0.5 to 30 μm, a thermal transfer image is formed on the porous ink receiving layer, and a transparent protective layer is provided on the thermal transfer image. Sheet. 2. The porous ink receiving layer has a large number of fine bubbles formed by mechanically stirring the resin-containing liquid, and the foaming ratio of the bubble-containing resin-containing liquid (compared with a constant weight of the stock liquid) The melt transfer recording sheet according to claim 1, wherein the ratio of the volume after foaming to the volume before foaming is 1 to 10 times. 3. A sheet-like support, and a porous ink-receiving layer formed on one surface of the sheet-like support and comprising a porous resin-containing film, wherein the average of the surface of the porous ink-receiving layer is Porous ink-receiving layer (a) of melt transfer type ink image-receiving sheet having pore diameter in the range of 0.5 to 30 μm
And the ink layer (b) of the thermal transfer ink sheet having a heat-fusible ink layer formed on the surface of the base material film so as to face each other, and imagewise heated from the back surface of the thermal transfer sheet to form an image on the porous ink receiving layer. A method for forming a fusion thermal transfer recording sheet, which comprises forming a thermal transfer image on the sheet, and then forming a transparent protective layer on the thermal transfer image.