JPH1035124A - Ink receptive sheet for fusion heat transfer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink receptive sheet which shows a high recording density, superior image quality and pencil writing properties when this sheet is used on a melt heat transfer color printer. SOLUTION: This ink receptive sheet for melt heat transfer consists of a sheet-like support and a porous ink receptive layer formed by applying a coating liquid obtained by foaming a mixed liquid comprising resin and pigment as main ingredients through mechanical stirring and drying the coat. In addition, the porous ink receptive layer contains pigment which has a BET method specific surface area of 20-600m<2> /g and/or an oil absorption of 70-400ml/100g based on JIS K5101. Further, the average diameter of a void in the surface of the porous ink receptive layer is 0.5-30μm and the apparent density of the coating layer is 0.05-0.8g/cm<3> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink receiving sheet for heat transfer (hereinafter, referred to as an ink receiving sheet), and more specifically, to a recording density when used in a heat transfer printer using a thermal head. The present invention relates to an ink receiving sheet having high image quality, excellent image quality, and excellent pencil writing.

[0002]

2. Description of the Related Art Conventionally, a thermal transfer printing method using a thermal transfer ink sheet and a thermal head has been widely used in printers such as word processors and facsimile machines because of its simple mechanism and easy maintenance. Fine paper has been used as the receiving sheet. However, in recent years, in order to obtain higher gradation reproducibility with full color thermal transfer recording, printers have changed the size of each dot from the conventional method of obtaining gradation without changing the size of one dot Has shifted to the variable dot system. In addition, the ink receiving sheet has excellent dot reproducibility and transfers a sufficient amount of ink so that the dot shape of the melt-heat-transferred ink is faithfully reproduced in full-color recording from low applied energy to high applied energy. The high recording density is an important quality of the recorded image.

[0003] In order to make the thermal transfer image full-color as described above, it is necessary to appropriately respond to the characteristics of the ink receiving sheet. That is, when a normal uncoated paper for printing is used in the full-color fusion thermal transfer system, a decrease in recording density, which is considered to be caused by low heat insulation, and poor dot reproducibility due to insufficient cushioning properties may occur. . If the surface of the ink receiving sheet is too rough,
If the ink is not transferred, that is, if the surface is too smooth or the surface is too smooth, the ink will not be anchored and the transferred ink will be back-transferred to the ink ribbon. Easier to do. All of these are phenomena that cause poor dot reproducibility. In addition to the decrease in recording density due to such poor dot reproducibility, a decrease in recording density due to low ink absorption of the molten ink receiving layer may occur.

Attempts to solve these problems have been made in JP-A-2-89690 and JP-A-64-27996.
In Japanese Patent Application Laid-Open Publication No. H11-157, it has been proposed to provide an undercoat layer containing hollow particles on a support in order to improve the cushioning property of the ink receiving sheet. However, the cushioning and heat insulating properties of the ink receiving sheet obtained by this method are still insufficient. When the hollow particles are dissolved in the organic solvent of the receiving layer, use an organic solvent-resistant polymer as an adhesive for the hollow particles, or place the organic solvent-resistant polymer on the layer containing the hollow particles. It is necessary to provide a layer, and this necessity complicates the manufacturing process of the ink receiving sheet and increases the cost.

As another attempt to solve the above problem, Japanese Patent Laid-Open Publication No. Hei 2-41287 discloses a method of forming a resin layer containing a component eluted in water on a sheet-like support mainly composed of plastic. In some cases, a water-soluble component is eluted and removed from the resin layer, thereby improving the ink receiving ability of the ink receiving sheet. However, in this case, a sufficient maximum density cannot be obtained or the printed image has no gloss. However, it has not been possible to satisfy the increasingly required quality of the ink receiving sheet. Further, since the ink receiving sheet is mainly composed of plastic, there are problems such as difficulty in recycling resources and lack of writing ability with a pencil or a mechanical pencil.

[0006]

SUMMARY OF THE INVENTION The present invention solves the drawbacks of the prior art and, when used in a fusion heat transfer type color printer, provides an ink receiving medium having high recording density, excellent image quality, and also having pencil writing properties. It is intended to provide a seat.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have formed a porous ink receiving layer on a sheet-like support, It has been found that the above-mentioned problems can be solved by optimizing the specific surface area or oil absorption of, and by optimizing the mixing ratio of this pigment, and have completed the present invention.

That is, the ink-receiving sheet of the present invention is obtained by coating a sheet-like support and at least one surface of the sheet-like support by foaming a mixed solution containing a resin and a pigment as main components by mechanical stirring. A porous ink receiving layer formed by applying and drying a working liquid, wherein the porous ink receiving layer has a BET specific surface area of 20 to 600.
a pigment having an oil absorption of 70 to 400 ml / 100 g based on m ² / g and / or JIS K5101; an average pore diameter of the surface of the porous ink receiving layer is 0.5 to 30 μm; The layer has an apparent density of 0.05 to 0.8 g / cm ³ .

Further, the mixing ratio of the pigment contained in the porous ink receiving layer of the ink receiving sheet of the present invention is preferably 5 to 100 parts by weight based on 100 parts by weight of the resin solid content.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a porous ink receiving layer formed on a sheet-like support contains a resin and a pigment as main components. Such a porous ink-receiving layer is obtained by mechanically stirring a liquid containing a mixture of a resin and a pigment to contain a large number of fine bubbles, and applying the bubble-containing resin coating liquid to a sheet-like support. It can be formed by coating and drying on the top.

The pigment used in the present invention is BET
Formula specific surface area 20-600m^Two/ G and / or JI
Oil absorption based on SK5101 is 70 to 400 ml / 1
00g, for example, calcined clay (BET specific surface area is
14-25m^Two/ G, oil absorption 70-120ml / 10
0 g), kaolin (BET specific surface area is 10 to 25 m) ^Two
/ G, oil absorption 35-50ml / 100g), light carbonic acid
Calcium (BET specific surface area is 2 to 35m^Two/ G, absorption
Oil amount 30-140ml / 100g), titanium oxide (B
ET type specific surface area is 5-30m^Two/ G, oil absorption 15 to 5
0 ml / 100 g), silica (BET specific surface area is 50
~ 700m^Two/ G, oil absorption of 40 to 290 ml / 100
g), magnesium carbonate (BET specific surface area is 20 to 3)
5m^Two/ G, oil absorption 120-180ml / 100g)
And the like, but are not limited thereto.
Not something. These pigments can be used alone or when necessary.
If necessary, two or more kinds can be used in combination.

A pigment is blended in the porous ink-receiving layer in order to impart pencil writability. The BET specific surface area of the pigment is preferably from ²⁰ to 600 m ² / g, more preferably from 40 to 500 m ² / g. ² / g. The oil absorption of the pigment based on JIS K5101 is 70 to 400 m.
1/100 g, more preferably 1/100 g.
It is 00 to 350 ml / 100 g.

When the pigment has a BET specific surface area of less than 20 m ² / g, the contact area between the pigment and the resin is insufficient. Around the part where the pigment of the porous ink receiving layer is present, a trouble occurs that the ink receiving layer is peeled off on the ink ribbon side,
Pencil writing may be poor. On the other hand, BE
If the T-type specific surface area exceeds 600 m ² / g, the contact area between the pigment and the resin becomes excessive, and the cushioning property, which is an important property as an ink receiving sheet, becomes insufficient, so that the image quality may deteriorate.

If the pigment has an oil absorption of less than 70 ml / 100 g, the contact area between the pigment and the resin is insufficient. Trouble that the ink receiving layer is peeled off to the ink ribbon side occurs around the part where the pigment of the ink receiving layer is present,
Insufficient ink receiving capacity may result in insufficient recording density. On the other hand, the oil absorption of the pigment is 400 ml / 100
When the value exceeds g, the ink may be localized near the pigment due to excessive ink receiving capacity, resulting in a rough image.

The blending ratio of the resin and the pigment for obtaining a good melt heat transfer image and further providing pencil writing properties is such that the pigment is 5 to 100 parts by weight with respect to 100 parts by weight of the resin solid content. And preferably 10 to 70 parts by weight. If the amount is less than 5 parts by weight, desired pencil writability cannot be obtained, and if it exceeds 100 parts by weight, the required strength of the porous ink receiving layer cannot be obtained, and a trouble of peeling off the coating layer during image formation occurs. In many cases, good images cannot be obtained.

The resin used for forming the porous ink receiving layer of the present invention includes, for example, polyvinyl alcohols having various molecular weights and saponification degrees and derivatives thereof, starches and derivatives thereof, and various kinds of chemicals such as oxidized starch. Starch, methoxycellulose, carboxymethylcellulose, cellulose derivatives such as methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide-acrylic acid ester copolymer, acrylic acid amide-acrylic acid ester-methacrylic acid ester copolymer, Alkaline salt of styrene-maleic anhydride copolymer, polyacrylamide and derivatives thereof, water-soluble resin such as polyethylene glycol, or polyvinyl acetate, polyurethane, styrene-butadiene copolymer Body (SBR latex), acrylonitrile - butadiene copolymer (NBR latex),
Methyl methacrylate-butadiene copolymer (MBR latex), polyacrylate, polymethacrylate, polyacrylate-styrene copolymer, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer Polymers, styrene-butadiene-acrylic copolymers, water-dispersible resins such as emulsions or latexes such as polyvinylidene chloride, as well as glue, casein, soy protein, gelatin, sodium alginate, etc. However, the present invention is not limited to this. These resins can be used alone or as a mixture of two or more as needed.

In the liquid material containing the mixture of the resin and the pigment before the formation of bubbles, if necessary, a known viscosity modifier, thickener, dispersant, dye, water-proofing agent, lubricant, crosslinking agent, A plasticizer or the like can be added.

The coating amount of the porous ink receiving layer on the sheet-like support is preferably ² to 40 g / m ² . When the coating amount is less than 2 g / m ² , it may be difficult to sufficiently cover the surface roughness of the sheet-like support, and an ink receiving sheet having a proper smoothness on the surface may not be obtained. In some cases, sufficient heat insulating properties and compressive deformation properties cannot be obtained. On the other hand, when it exceeds 40 g / m ² , the thickness of the porous ink receiving layer becomes excessively large, the bonding strength in the porous ink receiving layer decreases, and when the image is formed, the porous ink receiving layer becomes thin. In some cases, troubles such as peeling off occur, and good images cannot be formed. Therefore, it is necessary to exercise sufficient care in optimizing the coating amount of the porous ink receiving layer, as in optimizing the composition of the resin pigment mixture.

In the present invention, the porous ink-receiving layer is obtained by adding a large number of fine bubbles to a liquid mixture containing the above-mentioned resin and pigment as main components, coating the mixture on a sheet-like support, and drying. Although it can be obtained, there is no particular strict restriction on the method and equipment for forming and containing bubbles, and the coating method. The bubble-containing state of the bubble-containing liquid mixture is not particularly limited, but is preferably a volume ratio of the bubble-containing liquid mixture to the stock solution (hereinafter, referred to as an 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 of the cell content in the cell-containing liquid mixture, and means that as the expansion ratio increases, the thickness of the resin film (wall) forming the cells decreases. When the expansion ratio is the same, it means that the resin film becomes thinner as the solid content concentration of the liquid mixture before foaming is lower. As described above, when the resin film is thin, it may be difficult to maintain the strength of the obtained porous ink receiving layer at a sufficient level, and in this regard, the balance between the expansion ratio and the composition of the liquid mixture is not sufficient. Great care must be taken.

In addition, the mechanism of developing excellent molten ink transfer performance is based on the fact that the porous ink receiving layer and the ink receiving sheet according to the present invention involve physical properties such as structural properties, heat insulation properties, and compression properties. Conceivable. In terms of structural characteristics, the surface of the porous ink receiving layer formed on the sheet-like support has many fine pores,
The porous ink receiving layer is capable of absorbing the molten ink due to the capillary force, and further has a large number of pores contained in the porous ink receiving layer communicating with each other to form open cells. Good penetration of the molten ink into the
It is considered that high ink receiving capacity is exhibited.

In this regard, the size of the pores on the surface of the porous ink receiving layer formed on the sheet-like support is important. That is, when transferring the molten ink, to form a good image on the ink receiving sheet according to the present invention,
The average pore diameter on the surface of the porous ink receiving layer is 0.5 to 3
It is preferably 0 μm, and more preferably 0.5 to 20 μm. Pore diameter is its size (size)
This is related to the ability to capture the molten ink by the capillary phenomenon caused by the pores, and the smaller the pores, the greater the ability.
However, if the average pore diameter becomes excessive, the molten ink transferred into the pores may be buried or hinder good contact between the ink ribbon and the surface of the porous ink receiving layer, resulting in poor transfer or uneven transfer. In addition, a defective image cannot be formed due to poor dot reproduction. 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.

The size of the pores is directly related to the composition of the liquid mixture before the bubble formation / dispersion treatment, ie, the kind of the material, the mixing ratio, the bubbles, the coating, and the film thickness in the porous ink receiving layer after drying. Since it is often influenced by various factors such as the amount remaining as a component or the above-mentioned expansion ratio, coating method, etc., it is necessary to set appropriate conditions. Furthermore, the size of the pores on the surface of the porous ink receiving layer according to the present invention is also related to the size of the bubbles in the bubble-containing liquid mixture obtained by mechanical stirring, and generally, the smaller the bubbles in the liquid mixture, the smaller the size of the bubbles in the liquid mixture. Since the pores on the surface of the porous ink receiving layer after coating and drying are also reduced, the state of bubbles contained in the liquid mixture is not particularly limited, but the same size as the surface of the porous ink receiving layer, that is, the average diameter Is 0.5 ~
It is preferable that 30 μm microbubbles are dispersed and mixed, and more preferably the average diameter is 0.5 to 20 μm. The size of the contained bubbles can be measured with an image analyzer by photographing a part of the bubbles with an optical microscope.

In the present invention, in order to form a good image on the ink receiving sheet when the molten ink is transferred,
The apparent density of the porous ink receiving layer is 0.05 to 0.8.
g / cm ³ , preferably 0.1 to 0.5 g / cm ³
It is. If the apparent density is less than 0.05 g / cm ³ , a problem may occur that the ink receiving layer is peeled off to the ink ribbon side in the step of peeling the ink ribbon and the ink receiving sheet during image formation. On the other hand, when the apparent density is larger than 0.8 g / cm ³ , the image quality and the pencil writing property may be inferior.

In the present invention, a method for forming, containing and dispersing air bubbles in a liquid mixture (hereinafter referred to as a foaming method) includes, for example, a so-called confectionery foaming machine having a stirring blade rotating while carrying out planetary motion, and generally emulsifying and dispersing. Stirrers such as homomixers and cowles dissolvers used for
A device capable of mechanically stirring while continuously feeding air and a mixture of a liquid mixture into a closed system to disperse and mix air into fine bubbles, for example, manufactured by Gaston County of the United States, Stoke of the Netherlands And a continuous foaming machine can be used, but there is no particular strict restriction. In addition, due to the insufficient capacity of the equipment for mechanical stirring, a desired bubble-containing state cannot be obtained, or a foam stabilizer is used for the purpose of improving the stability of bubbles in the bubble-containing resin liquid. It can be appropriately selected and blended from a wide range of surfactants referred to as a foaming agent.

Examples of such surfactants include higher fatty acids, modified higher fatty acids, and alkali salts of higher fatty acids.
In particular, it can be used because it has a high effect of enhancing the foaming property of the liquid mixture and a high effect of improving the stability of the dispersed and contained bubbles. Although there is no particular limitation on the selection, it is reasonable to avoid using a material that may significantly impair the fluidity of the liquid mixture or impair coating workability.

The amount of the surfactant, such as the above-mentioned foam stabilizer and foaming agent, to be used is 100 parts by weight of the solid content of the aqueous dispersion type resin liquid or the mixture of the aqueous dispersion type resin liquid and the pigment. The solid content of the surfactant is preferably from 0 to 30 parts by weight, more preferably from 1 to 20 parts by weight. Even if the surfactant is used in a large amount exceeding 30 parts by weight, the effect may be saturated and the cost may be increased.

The coating method for forming the porous ink receiving layer on the sheet-like support includes a Meyer bar method,
The method can be arbitrarily selected from known methods such as a gravure roll method, a roll method, a reverse roll method, a blade method, a knife method, an air knife method, an extrusion method, and a cast method.

The sheet having a porous ink receiving layer of the present invention is obtained by applying a bubble-containing liquid mixture on a sheet-like support.
A good melt heat transfer image can be shown even when it is dry, but a machine calender consisting of two or more metal rolls, or a metal roll and a resin roll, or a metal roll and a cotton roll This porous ink receiving layer can be subjected to a finishing treatment by using a super calender constituted by appropriately combining the above to further improve the smoothness of the surface. Also, after coating, the surface of the porous ink receiving layer of the semi-dry or dry sheet is brought into contact with a mirror-finished heated or non-heated cast drum or the like to improve its surface smoothness. You may. However, if the smoothing treatment is performed under excessive pressure at this time, the resin wall surrounding the bubbles in the porous ink receiving layer is broken, and the ink receiving layer is densified, and the heat insulating property and the cushioning property are reduced, or the ink receiving property is reduced. Since the pores on the surface of the receiving layer are deformed or broken, the excellent ink transfer performance of the porous ink receiving layer may not be obtained. Therefore, it is necessary to sufficiently consider the processing conditions in the above-mentioned smooth finishing.

As the sheet-like support used in the present invention, paper such as paper containing cellulose as a main component, coated paper, laminated paper and the like, as well as cloths such as woven cloth and non-woven cloth can be used. is there. In addition, plastic films such as polyolefin, methacrylate, and cellulose acetate, and synthetic paper composed of polyolefin and pigment, and porous synthetic resin films such as expanded polyethylene terephthalate film and expanded polypropylene film can be used.
In these sheet supports, the better the heat insulation, the better the dot reproducibility and gradation reproducibility at the same applied energy, the recording density can be increased, and the same density and recording quality can be achieved. Since the amount of energy required to obtain it is small, it is also effective for energy saving. Further, when paper or coated paper containing pulp as a main component is used as a sheet-like support, there is an advantage that recycling is particularly possible.

Further, when the ink-containing sheet of the present invention is produced by applying the liquid mixture containing bubbles on the above-mentioned sheet-like support, the ink-receiving sheet itself is subjected to coating, drying, winding and the like in steps such as coating. Curling may occur with the surface inside or outside. In this case, if the ink receiving sheet is used after being processed into an image forming ink receiving sheet of a predetermined size by cutting, the paper may not be normally fed to the thermal transfer printer, or the running property inside the printer may be reduced. Trouble may occur. Also, since the fusion heat transfer recording method is a method in which a heat source is brought into contact with an ink ribbon and a dye component in the ink ribbon is transferred onto a recording ink receiving sheet, a porous ink receiving layer, which is an image forming surface, and a sheet-like support. Due to the difference in contraction or expansion characteristic due to heating of the body, the ink receiving sheet curls inside the apparatus, and the above-described trouble occurs. Due to such curling, an image is formed obliquely with respect to a normal paper surface direction, and wrinkles are easily generated in the ink receiving sheet inside the apparatus. Therefore, the contact between the ink ribbon and the ink receiving sheet is normally performed. Otherwise, poor ink transfer may occur, resulting in poor image quality.

In order to prevent various troubles caused by such curling, the difference in the shrinkage characteristic or the difference in the expansion characteristic between the porous ink receiving layer and the sheet-like support due to heating is minimized. It is desirable. For this purpose, an anti-curl layer may be applied or laminated on the back surface of the ink receiving sheet, that is, on the surface opposite to the porous ink receiving layer. There is no limitation on the material of the anti-curl layer, the forming method, the amount of coating, the amount of lamination, etc.
Optimization can be performed in consideration of various factors such as the type and thickness of the sheet-like support or the properties of the porous ink receiving layer, that is, the material composition, expansion ratio, and coating amount.

Further, depending on the material selection of the sheet-like support, the obtained ink receiving sheet may be subjected to various frictional forces due to the mechanism of the apparatus when it travels in the printer, or the influence of a decrease in humidity inside the apparatus due to heating. , Alone or in combination, may charge the ink receiving sheet with static electricity. When a large number of images are continuously formed in such a state, an image forming surface of the ink receiving sheet,
The back surface of the next ink receiving sheet electrostatically comes into close contact with the sheet, making double feeding easy. In particular, since various types of plastic sheets or synthetic paper have an inherently easy-to-charge property, when they are used as a sheet-like support, the static electricity may be generated during the sheeting process by cutting or during storage after processing. Due to the occurrence, double feeding of the front and back of the sheet becomes easy. As a matter of course, even when paper is used as the sheet-like support, the above-described trouble can occur. It is extremely effective to form a so-called antistatic layer on the back surface of the ink receiving sheet in order to prevent such troubles caused by charging. Charging can be achieved by using an antistatic material or reducing the coefficient of friction between the back surface of the ink receiving sheet and the porous ink receiving layer. Therefore, the antistatic layer can be formed by appropriately selecting from a wide range of materials and methods similarly to the formation of the anticurl layer.

The anti-curl layer and the antistatic layer are
Although it is possible to obtain desired performance by individually forming on the back surface of the sheet-like support, simplification of the manufacturing process, reduction of the manufacturing cost or desired functional level, etc.
By appropriately selecting a forming method, a single layer can be formed to achieve the object. That is, it is also possible to provide trouble prevention performance such as curling prevention and antistatic with a single layer. Therefore, there is no limitation on the number of layers formed on the back surface of the sheet-shaped support.

[0034]

The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited by these. In the examples and comparative examples, all “parts” represent “parts by weight” with respect to the solid content of the resin.

Using a stirrer (trade name: Kenmix Iko PRO, manufactured by Aikosha Seisakusho), a liquid mixture having the composition shown in each of Examples and Comparative Examples (solid content was adjusted to 35%) was used. The foaming treatment was performed by adjusting the stirring time at 490 rpm. Immediately after the foaming treatment, the coated amount (dry) of the air-containing liquid mixture was applied to the surface of a high-quality paper having a basis weight of 75 g / m ² using an applicator bar to a dry amount of 15 g / m 2.
^The resulting mixture was coated and dried to form a porous ink receiving layer to give an ink receiving sheet.

Example 1 Liquid mixture composition 1 Resin; 100 parts of aqueous polyurethane resin (trade name: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: 20 parts of silica (trade name: Mizukasil P-705, manufactured by Mizusawa Chemical Co., Ltd.) BET specific surface area 300 m ² / g, oil absorption 280 ml / 100 g) Foam stabilizer; higher fatty acid type (trade name: SN foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG gum, No. Manufactured by Ichigyo Pharmaceutical Co., Ltd.)

The liquid mixture 1 having the above composition was subjected to a foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 4.5 μm,
The density was 0.24 g / cm ³ .

Example 2 Liquid mixture composition 2 Resin; 100 parts of aqueous polyurethane resin (trademark: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo Co., Ltd.) Pigment: 20 parts of silica (trademark: Mizukasil P-526, manufactured by Mizusawa Chemical Co., Ltd.) BET specific surface area 125 m ² / g, oil absorption 235 ml / 100 g) Foam stabilizer; 5 parts of higher fatty acid type (trade name: SN Foam 200, manufactured by San Nopco) Thickener; 5 parts of carboxymethyl cellulose (trade name: AG gum, No. Manufactured by Ichigyo Pharmaceutical Co., Ltd.)

The liquid mixture 2 having the above composition was subjected to foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having an expansion ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 4.8 μm,
The density was 0.26 g / cm ³ .

Example 3 Liquid mixture composition 3 Resin; 100 parts of aqueous polyurethane resin (trade name: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo Co., Ltd.) Pigment: 20 parts of light calcium carbonate (trade name: Callite KT, manufactured by Shiraishi Calcium Co., Ltd.) BET specific surface area 35 m ² / g, oil absorption 140 ml / 100 g) Foam stabilizer; higher fatty acid type (trade name: SN foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG gum, No. Manufactured by Ichigyo Pharmaceutical Co., Ltd.)

The liquid mixture 3 having the above composition was subjected to foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having an expansion ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 4.9 μm,
The density was 0.31 g / cm ³ .

Example 4 Liquid mixture composition 4 Resin; 100 parts of polyacrylate resin (trade name: AA-52, manufactured by Kanebo NSC) Aqueous polyurethane resin Pigment: 20 parts of silica (trade name: Mizukasil P-705, Mizusawa Chemical Co., Ltd.) BET specific surface area 300 m ² / g, oil absorption 280 ml / 100 g) Foam stabilizer; higher fatty acid (trade name: SN foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG gum, Daiichi Kogyo Seiyaku Co., Ltd.)

The liquid mixture 4 having the above composition was subjected to foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having an expansion ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 5.1 μm,
The density was 0.30 g / cm ³ .

Example 5 Liquid mixture composition 5 Resin; 100 parts of aqueous polyurethane resin (trade name: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: silica 20 parts (trade name: Mizukasil P-705, manufactured by Mizusawa Chemical Co., Ltd.) BET specific surface area 300 m ² / g, oil absorption 280 ml / 100 g) Foam stabilizer; higher fatty acid ammonium salt type 5 parts (trademark: Boncoat F-1, manufactured by Dainippon Ink and Chemicals, Inc.) Thickener: carboxymethyl cellulose 5 parts (Trademark: AG gum, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

The liquid mixture 5 having the above composition was subjected to a foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 4.6 μm,
The density was 0.25 g / cm ³ .

Example 6 Liquid Mixture Composition 6 Resin; 100 parts of aqueous polyurethane resin (trade name: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: 50 parts of silica (trade name: Mizukasil P-705, manufactured by Mizusawa Chemical Co., Ltd.) BET specific surface area 300 m ² / g, oil absorption 280 ml / 100 g) Foam stabilizer; higher fatty acid type (trade name: SN foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG gum, No. Manufactured by Ichigyo Pharmaceutical Co., Ltd.)

The liquid mixture 6 having the above composition was subjected to foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having an expansion ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 5.3 μm,
The density was 0.38 g / cm ³ .

Example 7 Liquid mixture composition 7 Resin; 100 parts of aqueous polyurethane resin (trade name: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: 20 parts of silica (trade name: Mizukasil P-752, manufactured by Mizusawa Chemical Co., Ltd.) BET specific surface area 450 m ² / g, oil absorption 160 ml / 100 g) Foam stabilizer; higher fatty acid type (trade name: SN Foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG gum, No. Manufactured by Ichigyo Pharmaceutical Co., Ltd.)

The liquid mixture 7 having the above composition was subjected to a foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 4.4 μm,
The density was 0.26 g / cm ³ .

Example 8 Liquid mixture composition 8 Resin; 100 parts of an aqueous polyurethane resin (trade name: Adekabon titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: calcined clay 20 parts (trade name: ANSILEX, manufactured by ENGELHARD, BET ratio) Surface area: 15 m ² / g, oil absorption: 80 ml / 100 g) Foam stabilizer: 5 parts of higher fatty acid (trade name: SN Foam 200, manufactured by San Nopco) Thickener: 5 parts of carboxymethyl cellulose (trade name: AG gum, Daiichi Kogyo Seiyaku) Company)

The liquid mixture 8 having the above composition was subjected to a foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having an expansion ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 4.6 μm,
The density was 0.25 g / cm ³ .

Example 9 Liquid mixture composition 9 Resin; 100 parts of aqueous polyurethane resin (trademark: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: 20 parts of magnesium carbonate (trademark: Magnesium carbonate Venus, Kamishima Chemical Co., Ltd.) BET specific surface area 28 m ² / g, oil absorption 140 ml / 100 g) Foam stabilizer; higher fatty acid type (trade name: SN Foam 200, manufactured by San Nopco) 5 parts Thickener: carboxymethyl cellulose 5 parts (trade name: AG gum, Daiichi Kogyo Seiyaku Co., Ltd.)

The liquid mixture 9 having the above composition was subjected to a foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having an expansion ratio of 4.0, and then immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 4.6 μm,
The density was 0.27 g / cm ³ .

Example 10 Liquid mixture composition 10 Resin; 100 parts of aqueous polyurethane resin (trade name: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment; clay 20 parts (trade name: HYDRAGLOSS 90, manufactured by JM HUBER) BET specific surface area: 22 m ² / g, oil absorption: 40 ml / 100 g) Foam stabilizer; 5 parts of higher fatty acid (trade name: SN Foam 200, manufactured by San Nopco) Thickener; 5 parts of carboxymethyl cellulose (trade name: AG gum, No. Manufactured by Ichigyo Pharmaceutical Co., Ltd.)

The liquid mixture 10 having the above composition was subjected to a foaming treatment for 8 minutes by the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 4.8 μm.
m, and the density was 0.28 g / cm ³ .

Example 11 Liquid mixture composition 11 Resin; 100 parts of aqueous polyurethane resin (trade name: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo Co., Ltd.) Pigment: 20 parts of titanium oxide (trade name: Aerosil titanium oxide P-25, Japan Aerosil, BET specific surface area 50 m ² / g, oil absorption 95 ml / 100 g) Foam stabilizer; higher fatty acid (trade name: SN foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG) Gum, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

The liquid mixture 11 having the above composition was subjected to a foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having an expansion ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 4.7 μm.
m, and the density was 0.26 g / cm ³ .

Example 12 Liquid mixture composition 12 Resin; 100 parts of an aqueous polyurethane resin (trademark: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: 20 parts of silica (trademark: Syloid 800, manufactured by Fuji Devison, BET Specific surface area 300 m ² / g, oil absorption 310 ml / 100 g) Foam stabilizer; higher fatty acid type (trade name: SN Foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG gum, Daiichi Kogyo Co., Ltd.) Pharmaceutical company)

The liquid mixture 12 having the above composition is subjected to foaming treatment for 8 minutes by the above-mentioned stirrer, and a foamed mixed solution having a foaming ratio of 4.0 is prepared, immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 4.5 μm.
m, and the density was 0.25 g / cm ³ .

Example 13 The liquid mixture composition 1 of Example 1 was subjected to a foaming treatment for 3 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 2.0. A layer was formed to produce an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 8.5 μm, and the density was 0.46 g / cm ³ .

Example 14 The liquid mixture composition 1 of Example 1 was subjected to a foaming treatment for 15 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 5.0. A layer was formed to produce an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 2.5 μm, and the density was 0.20 g / cm ³ .

Example 15 The liquid mixture composition 1 of Example 1 was subjected to a foaming treatment for 25 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 6.0. A layer was formed to produce an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 2.0 μm, and the density was 0.14 g / cm ³ .

Example 16 The liquid mixture composition 1 of Example 1 was subjected to a foaming treatment for 1 minute with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 1.5. A layer was formed to produce an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 12.5 μm, and the density was 0.65 g / cm ³ .

Example 17 The liquid mixture composition 1 of Example 1 was subjected to a foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, left for 5 minutes, applied and dried. A porous ink receiving layer was formed to prepare an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 15.0 μm,
The density was 0.41 g / cm ³ .

Example 18 The liquid mixture composition 1 of Example 1 was subjected to a foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, left for 10 minutes, applied and dried. A porous ink receiving layer was formed to prepare an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 28.0 μm.
m and the density were 0.42 g / cm ³ .

Comparative Example 1 The liquid mixture composition 1 of Example 1 was subjected to no foaming treatment.
The ink receiving layer was formed by coating and drying to prepare an ink receiving sheet. The density of the obtained ink receiving layer is 1.1 g.
/ Cm ³ .

Comparative Example 2 The liquid mixture composition 1 of Example 1 was subjected to foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, left for 15 minutes, applied and dried. A porous ink receiving layer was formed to prepare an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 35.0 μm.
m and density were 0.44 g / cm ³ .

Comparative Example 3 Liquid mixture composition 13 Resin; 100 parts of aqueous polyurethane resin (trademark: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment; silica 120 parts (trademark: Mizukasil P-705, manufactured by Mizusawa Chemical Co., Ltd.) BET specific surface area 300 m ² / g, oil absorption 280 ml / 100 g) Foam stabilizer; higher fatty acid type (trade name: SN foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG gum, No. Manufactured by Ichigyo Pharmaceutical Co., Ltd.)

The liquid mixture 13 having the above composition was subjected to foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 6.2 μm.
m and density were 0.44 g / cm ³ .

Comparative Example 4 Liquid mixture composition 14 Resin; 100 parts of aqueous polyurethane resin (trademark: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo Co., Ltd.) Pigment: 20 parts of silica (trademark: Sylysia 770, manufactured by Fuji Silysia, BET Specific surface area 700 m ² / g, oil absorption 95 ml / 100 g) Foam stabilizer; higher fatty acid type (trade name: SN foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG gum, Daiichi Kogyo Co., Ltd.) Pharmaceutical company)

The liquid mixture 14 having the above composition was subjected to a foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, which was immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 4.9 μm.
m, and the density was 0.29 g / cm ³ .

Comparative Example 5 Liquid mixture composition 15 Resin; 100 parts of aqueous polyurethane resin (trademark: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: 20 parts of light calcium carbonate (trademark: Albuquer HO, Specialty Mineral) BET specific surface area 11 m ² / g, oil absorption 78 ml / 100 g) Foam stabilizer; higher fatty acid (trade name: SN Foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG gum) , Manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

The liquid mixture 15 having the above composition was subjected to foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having an expansion ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 5.2 μm.
m and the density were 0.33 g / cm ³ .

Comparative Example 6 Liquid mixture composition 16 Resin; 100 parts of aqueous polyurethane resin (trademark: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: 20 parts of light calcium carbonate (trademark: Brilliant 15, manufactured by Shiraishi Calcium Co., Ltd.) BET specific surface area: 11.5 m ² / g, oil absorption: 43.5 ml / 100 g) Foam stabilizer; higher fatty acid (trade name: SN foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG gum, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

The liquid mixture 16 having the above composition was subjected to a foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter of the surface of the obtained porous ink receiving layer was 5.3 μm.
m and the density were 0.31 g / cm ³ .

Comparative Example 7 Liquid Mixture Composition 17 Resin; 100 parts of aqueous polyurethane resin (trade name: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: 20 parts of heavy calcium carbonate (trade name: Softon 2200, Shiraishi Calcium Co., Ltd.) BET specific surface area 2.2 m ² / g, oil absorption 38 ml / 100 g) Foam stabilizer; higher fatty acid (trade name: SN foam 200, manufactured by San Nopco) 5 parts Thickener; carboxymethyl cellulose 5 parts (trade name: AG) Gum, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

The liquid mixture 17 having the above composition was subjected to a foaming treatment for 8 minutes by the above-mentioned stirrer to prepare a bubble-containing mixed solution having a foaming ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 5.8 μm.
m and the density were 0.33 g / cm ³ .

Comparative Example 8 Liquid mixture composition 18 Resin; 100 parts of aqueous polyurethane resin (trade name: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo KK) Pigment: 20 parts of calcium silicate (trade name: Toyo Hero, manufactured by Toyo Denka Co., Ltd.) BET specific surface area 350 m ² / g, oil absorption 630 ml / 100 g) Foam stabilizer; 5 parts of higher fatty acid (trade name: SN foam 200, manufactured by San Nopco) Thickener; 5 parts of carboxymethyl cellulose (trade name: AG gum, Daiichi Industrial Pharmaceutical Company)

The liquid mixture 18 having the above composition was subjected to foaming treatment for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing mixed solution having an expansion ratio of 4.0, and immediately applied and dried to form a porous ink receiving layer. And an ink receiving sheet. The average pore diameter on the surface of the obtained porous ink receiving layer was 5.0 μm,
The density was 0.30 g / cm ³ .

Evaluation method In Examples and Comparative Examples, the measurement of the pore diameter of the porous ink receiving layer, the measurement of the apparent density of the coating layer, the evaluation of the transferred ink image, and the pencil writing property were carried out by the following methods. . Table 1 shows the measurement and evaluation results.

[Expansion Ratio] The expansion ratio was determined by dividing the weight of 100 ml of the liquid mixture (stock solution) before the expansion treatment by the weight of 100 ml of the liquid mixture containing bubbles after the expansion treatment.

[Coating Layer Density] Coating layer density (g / cm ³ )
= A / B. Where A = weight of coated paper (g / m ² ) −weight of base paper (g / m ² ) B = paper thickness of coated paper (μm) −paper thickness of base paper (μm)

[Measurement Method of Average Pore Diameter on Surface] The average pore diameter on the surface of the porous ink receiving layer was determined by taking a photograph of the surface of the receiving layer using a scanning electron microscope or an optical microscope, and then taking a photograph of the surface. The outline of the pores is accurately drawn on a transparent film with a black pen or the like, and further, a drum scanner (trademark: 2605 type drum scan densitometer,
Abe Design Co., Ltd.) optically reads the information on the outline of the pores and uses this information as an image analyzer (trademark: Luzex II)
I, manufactured by Nireco). Since the shape of the pores formed on the surface of the porous ink receiving layer is not necessarily a perfect circle, the average pore diameter is converted to a circle equivalent diameter based on the area within the contour of the pore obtained by image analysis. And displayed.

[Recording Performance] The ink receiving sheet having the porous ink receiving layer obtained in each of Examples 1 to 8 and Comparative Examples 1 to 7 was conditioned at 20 ° C. and 65% relative humidity for 24 hours. , Thermal transfer color printer (trademark: True
print 2200, manufactured by Victor Company of Japan, Ltd .: originally a sublimation transfer type image forming apparatus, but modified so as to be able to form an image of the melt heat transfer type), and the melt heat transfer recording was performed. The reflection density of the obtained ink transfer image was measured with a Macbeth reflection densitometer and evaluated visually as described below. (1) The highest density is obtained by using a Macbeth reflection densitometer RD-
The reflection density was measured for each applied energy using 914 (trademark), and the highest reflection density value was shown. (2) The image quality was evaluated by observing the density unevenness of the ink transferred from the ink ribbon to the receiving layer, and evaluated in three stages of △, Δ, and × in order of good quality without unevenness. (3) The peeling of the recording layer is performed by observing the image formed on the receiving layer and observing the images in the order of も の, Δ,
The evaluation was made in three stages of x.

[Pencil Writability] The ink receiving sheet having the porous ink receiving layer obtained in the above Examples and Comparative Examples was conditioned at 20 ° C. and 65% relative humidity for 24 hours.
Handwriting was performed with a pencil (HB), and evaluation was made in three stages of ○, Δ, and × in order of clear handwriting. Table 1 shows the results of these evaluations.

The evaluation criteria in each evaluation are ○ and Δ levels suitable for practical use, while × levels are not suitable for practical use.

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[Table 1]

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[Table 2]

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EFFECT OF THE INVENTION The melt thermal transfer ink image of the ink receiving sheet for melt thermal transfer obtained according to the present invention has a high recording density, excellent image quality and surface strength, and at the same time has a pencil writing property. It is possible to use the sheet practically and greatly contribute to the industry.

Claims (3)

[Claims] 1. A coating liquid obtained by subjecting a mixed liquid mainly composed of a resin and a pigment to foaming treatment by mechanical stirring to at least one surface of the sheet-shaped support and at least one surface of the sheet-shaped support, and drying the coating liquid. And a porous ink receiving layer having a BET specific surface area of 20 to 6 in the porous ink receiving layer.
Oil absorption based on 00m ² / g and / or JIS K5101 is a pigment which is 70~400ml / 100g, average pore diameter of the surface of the porous ink-receiving layer is 0.5 to 30 m, and coated An ink receiving sheet for a thermal transfer printing, wherein the apparent density of the layer is 0.05 to 0.8 g / cm ³ . 2. The mixing ratio of the pigment contained in the porous ink receiving layer is 5 to 1 with respect to 100 parts by weight of the resin solid content.
2. The ink receiving sheet according to claim 1, wherein the amount is 00 parts by weight. 3. The melt according to claim 1, wherein the pigment contained in the porous ink receiving layer is at least one selected from calcined clay, kaolin, light calcium carbonate, titanium oxide, silica, and magnesium carbonate. Ink receiving sheet for thermal transfer.