JPH09323485A - Melt transfer type ink image receiving sheet and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melt transfer ink image receiving sheet having easy control of pore size on the surface of a receiving layer, high recording density, excellent gradation reproducibility, dot reproducibility and color clarity. SOLUTION: The ink image receiving sheet comprises a sheet-like support, and a porous ink receiving layer formed of a resin-containing liquid containing a water dispersion type resin as a main component on one surface of the support, wherein the water-holding value by a potassium permanganate method of the resin is in a range 5 to 450sec at the 38wt.% of solid content concentration and the mean pore size on the surface of the porous ink receiving layer is in a range of 0.5 to 30μm.

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 ink image receiving sheet and a method for manufacturing the same. More specifically, when the present invention is used in a fusion transfer type thermal transfer printer using a thermal head, the print ink image has high recording density and excellent gradation reproducibility, dot reproducibility and color image sharpness. And a method for producing 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. High quality paper has been used as the melt transfer type ink image receiving sheet (image receiving sheet). However, in recent years, in order to obtain higher gradation reproducibility than before with the full-color thermal transfer recording, the size of each dot has been changed from the conventional method of obtaining gradation without changing the size of one dot in the printer. In the image receiving sheet, the dot shape of the melt-transferred ink is faithfully reproduced in full-color recording from low applied energy to high applied energy. A large amount of ink is transferred, and high recording density is required as an important quality of a recorded image.

With respect to the full-color thermal transfer image as described above, it is necessary to appropriately correspond the characteristics of the image receiving sheet. In other words, when non-coated paper for ordinary printing is used in the full-color hot-melt transfer method, a decrease in recording density, which is considered to be due to low heat insulation, and defective dot reproducibility due to insufficient cushioning may occur. There is. Further, if the surface is too rough, a phenomenon occurs in which the ink is not transferred, that is, missing, or if the surface is too smooth, the anchoring effect of the ink becomes insufficient and the ink is transferred. A phenomenon that ink is reversely transferred to an ink ribbon, that is, missing is likely to occur. Any of these causes a poor dot reproducibility. In addition to the decrease in the recording density due to the poor dot reproducibility as described above, the decrease in the recording density due to the low ink absorbability of the molten ink image receiving layer may occur.

As an attempt to solve these problems, it has been proposed to provide an undercoat layer containing hollow particles on a support (Japanese Patent Laid-Open Nos. 2-89690 and 64-27996). . However, this attempt is still insufficient in improving the cushioning property and heat insulating property of the image receiving sheet. In addition, in this attempt, when the hollow particles are dissolved in the organic solvent of the receiving layer, an organic solvent resistant polymer is used as an adhesive for the hollow particles, or a polymer containing a hollow particle is used. It is necessary to provide an organic solvent-based polymer layer, which poses a manufacturing problem.

As another attempt to solve the above problem, on a sheet-shaped support containing plastic as a main component,
It has also been proposed to form a resin layer containing a component that dissolves in water and elute and remove water-soluble components from this resin layer to form fine pores, thereby improving the ink receiving ability of the image receiving sheet (special feature). (Kaihei 2-41287). However, in this case, the maximum density is still insufficient, or the printed image does not have gloss, and the quality requirements for the image receiving sheet have not been increased. Further, since the image receiving sheet is mainly composed of plastic, it is difficult to recycle resources.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above problems of the prior art and is excellent in gradation reproducibility, dot reproducibility and color image sharpness when used in a thermal transfer color printer, and It is an object of the present invention to provide a melt transfer type ink image-receiving sheet capable of obtaining an ink image recording having a high recording density.

[0007]

The melt transfer type ink image-receiving sheet of the present invention comprises a sheet-like support and a resin-containing liquid containing a water-dispersible resin as a main component on one surface of the support. A water-dispersible resin having a water retention value by the potassium permanganate method in the range of 5 to 450 seconds at a solid concentration of 38% by weight, and the porous ink-receiving layer Is characterized in that the average pore diameter of the surface is in the range of 0.5 to 30 μm. Further, in the melt transfer type ink image-receiving sheet of the present invention, the water-dispersible resin is preferably at least one selected from polyurethane, styrene-acryl copolymer, and styrene-butadiene copolymer.

Further, the method for producing the melt transfer type ink image-receiving sheet of the present invention is mainly composed of a water-dispersible resin whose water retention value by the potassium permanganate method is in the range of 5 to 450 seconds at a solid concentration of 38% by weight. A resin-containing liquid in which a large number of fine bubbles having a foaming ratio (volume ratio before and after foaming compared with a constant weight paint) exceeding 1 and 10 times or less is formed by mechanically stirring the resin-containing liquid The sheet-shaped support is coated on one surface and dried to form a porous ink-receiving layer having an average pore diameter on the surface in the range of 0.5 to 30 μm.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a result of intensive studies to achieve the above object, the present inventor has found that in recording by a melt thermal transfer printer, a resin-containing liquid containing a water-dispersible resin having a specific water retention value as a main component is machined. Dot reproducibility by using an image receiving sheet having a porous ink receiving layer having a large number of fine pores formed by coating on one surface of a sheet-shaped support with static stirring and drying. The present invention has been completed by finding that high density recording excellent in gradation reproducibility and color image sharpness can be realized. In the present invention, the porous ink receiving layer formed on the sheet-shaped support contains a water-dispersible resin, or a water-dispersible resin and a pigment as main components. Such a porous ink receiving layer, a liquid material containing a water-dispersible resin, or a mixture of a water-dispersible resin and a pigment is mechanically stirred to form and contain a large number of fine bubbles therein. It can be formed by coating and drying the liquid containing a resin containing bubbles on a support. Here, the water-dispersible resin contains a hydrophilic group,
Therefore, it means a resin that can be stably dispersed in water.

It is considered that physical properties such as structural characteristics and compression characteristics of the porous ink-receiving layer and the image-receiving sheet are involved in the mechanism of expressing the excellent suitability for transfer of the molten ink in the present invention. In terms of structural characteristics, since the surface of the porous ink image-receiving layer formed on the support has many fine pores, the molten ink is absorbed by the capillary force, and further, the porous ink is used. Since the large number of pores contained in the image receiving layer are in communication with each other (constituting open cells), the permeability of the molten ink into the porous ink image receiving layer is good, and high ink It is considered to develop a receptive capacity.

In this respect, the size of the pores on the surface of the porous ink receiving layer formed on the image receiving sheet is important. 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 porous ink receiving layer needs to be in the range of 0.5 to 30 μm. Yes, preferably 0.5 to 20
It is in the range of μm. Pore diameter is its size
It is related to the ability to capture the molten ink by the capillary phenomenon due to, and the smaller the pores, the greater the ability.
If the size of the pores is too large, the transfer ink will be buried in the pores, or it will cause poor transfer or uneven transfer because it interferes with good contact between the ink ribbon and the porous ink receiving layer surface. 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.

The size of the pores on the surface of the porous ink receiving layer in the present invention is determined by the composition of the water-dispersible resin-containing mixed liquid before the formation and dispersion of bubbles, that is, the kind of material, the blending ratio,
Appropriate conditions are often influenced by various factors such as air bubbles, amount remaining as a component directly related to the film thickness in the porous ink receiving layer after coating and drying, foaming ratio, coating method, etc. Setting is required. The size of the pores is particularly related to the size of the bubbles in the resin solution containing bubbles obtained by mechanical stirring. Generally, the smaller the bubbles in the resin solution containing the resin, the smaller the ink reception after coating and drying. Since the pores on the surface of the layer are also small, the state of bubbles in the water-dispersed resin-containing mixed liquid is not particularly limited, but the same size as the surface of the porous ink-receiving layer, that is, an average diameter of 0.5 to It is preferable that fine bubbles of 30 μm are dispersed and mixed, and more preferably, the average diameter is 0.
It is preferably in the range of 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.

It is important that the water-dispersible resin used in the present invention has a water retention value by the potassium permanganate method of 5 to 450 seconds when the solid content concentration is adjusted to 38% by weight. Preferably, it is in the range of 50 to 450 seconds. Regarding the solid content concentration of the water-dispersible resin for water retention value measurement, if the concentration is too high, the measurement time becomes unnecessarily long, while if the concentration is too low, the measurement accuracy will decrease. 38% by weight is determined to be optimal. In the case of a water-dispersible resin having a water retention value of less than 5 seconds, the resin-containing liquid is subjected to mechanical agitation to deteriorate the stability of bubbles formed and dispersed (breaking bubbles or coalescence of bubbles with each other). It tends to occur), and it becomes difficult to hold fine bubbles.
As a result, a preferable pore diameter on the surface of the porous ink receiving layer cannot be obtained, and the recording performance of the fusion type thermal transfer image receiving sheet is deteriorated. On the other hand, in the case of a resin-containing liquid using a water-dispersible resin having a water retention value of more than 450 seconds, there is no problem in bubble stability, but the viscosity of the bubble-containing resin liquid is agitated with the formation and dispersion of bubbles. There is a case where the temperature rises significantly or gelation occurs in extreme cases compared to before the treatment. As a result, the coatability on the entire surface of the support may be deteriorated, which may cause problems such as uneven coating and non-coating. Further, since the mechanical stirring process consumes excessive energy, it is disadvantageous from the economical and energy saving viewpoints.

The water retention value is measured by the potassium permanganate method, which is a method generally used in the field of surfactants. For example, a filter paper of a certain size is used and its four edges are folded inward. , Float on a water-dispersible resin with a constant solid content in a petri dish, sprinkle about 0.1 g of powdered potassium permanganate on the surface of the filter paper, and in the water-dispersible resin (especially at the interface with the filter paper). The water retention value is determined by measuring the time (seconds) until the water) is gradually sucked up and permeates through the filter paper to dissolve the powdery potassium permanganate in red.

Generally, the water retention value is a value indicating the hydration power or the ease of capturing water molecules, and the amount of hydrophilic groups such as hydroxyl groups and other polar groups in the resin, the molecular weight, the crosslinked structure, etc. It is due to. Regarding the water retention control of the water-dispersible resin, as a synthetic method for increasing the hydration power, there is a method of introducing a hydroxyl group, a carboxyl group, or the like, for example, a structure such as polyvinyl alcohol or polyacrylate. The one containing is shown. Further, the higher the molecular weight or the higher the degree of crosslinking, the higher the water retention tends to be.

The water-dispersible resin having a water retention value in the range of 5 to 450 seconds is not particularly limited, but examples thereof include polyurethane and styrene-butadiene copolymer (S
BR latex), acrylonitrile-butadiene copolymer (NBR latex), methyl methacrylate-butadiene copolymer (MBR latex), styrene-acrylic copolymer, polyacrylic acid ester, polymethacrylic acid ester, polyvinyl acetate, vinyl chloride. -A vinyl acetate copolymer, an ethylene-vinyl acetate copolymer, a styrene-butadiene-acrylic copolymer, a water-dispersible resin such as polyvinylidene chloride, or the like is used.
Among these, polyurethane, styrene-acrylic copolymer, styrene-butadiene copolymer and the like are preferably used. These water-dispersible resins can be used alone or in combination of two or more, if necessary. Specific examples include polyurethane resin (trademark: NeoRezR-9637, water retention value 420 seconds) manufactured by Zeneca Corporation, styrene-acrylic copolymer resin (trademark: KG-2010, water retention value) manufactured by Arakawa Chemical Industry Co., Ltd. 85 seconds), SBR latex (trademark: L-1763, water retention value 6 seconds) manufactured by Asahi Kasei Kogyo Co., Ltd., and the like.

In the present invention, the reason why particularly excellent effects are obtained in gradation reproducibility, dot reproducibility, color clarity, etc. is that the water-dispersible resin having a high water retention value in the range of 5 to 450 seconds. This is considered to be because the use of is capable of suppressing the coalescence of bubbles, suppressing the generation of large pores, keeping the average pore diameter of the surface small, and forming a porous ink receiving layer having a good distribution. In other words, when a water-dispersible resin with insufficient water retention is used, bubbles move abruptly between liquids (water) between the foam films (movement due to the pressure difference between the foam films, evaporation in the drying process, to the base paper). However, if there is a substance having a high water retention property between the foam films, it is considered that this rapid movement of water can be alleviated and the coalescence of bubbles can be suppressed. As a result, for example, at a specific expansion ratio, it becomes easy to control the pore diameter of the surface of the finally obtained porous ink receiving layer.

In the porous ink receiving layer of the present invention,
It is also possible to use a pigment as required, for example, zinc oxide, titanium oxide, calcium carbonate, silicic acid, silicate,
Clay, talc, mica, calcined clay, inorganic pigments such as aluminum hydroxide, barium sulfate, lithopone and colloidal silica, true spheres such as polystyrene, polyethylene, polypropylene, epoxy resin, styrene-acrylic copolymer, hollow or various An organic pigment called a plastic pigment of a type processed into a shape, starch powder, cellulose powder, and the like can be used, but are not limited thereto. In addition, these pigments can be used alone or in combination of two or more, if necessary.

The porous resin coating film of the present invention is
As can be inferred from the structure, it is hard to say that the coating strength is essentially strong, and therefore the addition of various pigments further lowers the coating strength, which may cause troubles such as image peeling. is there. Therefore, when forming a porous ink-receiving layer by adding various pigments to the water-dispersed resin-containing liquid, consider the overall quality of the image-receiving sheet and use it at an appropriate blending ratio. Is natural. Also,
If necessary, a known water retaining agent, viscosity modifier, dispersant, dyeing agent, water resistance agent, lubricant, cross-linking agent, plasticizer may be added to the liquid material containing the resin before the formation of bubbles or the mixture of the resin and the pigment. Etc. can be added.

It is also possible to use a water retention agent in the resin-containing material as long as the effect of the present invention is not impaired. For example, carboxymethyl cellulose, methyl cellulose, cellulose derivatives such as hydroxyethyl cellulose in the natural system, and sodium alginate, in the synthetic system, sodium polyacrylate, alkali thickening type acrylic emulsion, polyether modified acrylic polymer and the like. However, the present invention is not limited to these. These water retention agents can be used alone or in combination of two or more, if necessary.

The viscosity modifier is not particularly limited, but examples thereof include polyvinyl alcohol and its derivatives having various molecular weights and saponification degrees, starch, and starch derivatives (for example, oxidized starch and cationized starch). Various modified starches) and water-soluble resins such as polyethylene glycol can be included. Polyvinyl alcohols have the effect of improving the dyeability of fluorescent dyes. In addition, starches have advantages such as biodegradability.

In the present invention, the method for forming and dispersing the bubbles in the water-dispersible resin-containing liquid and the equipment are not particularly limited, but, for example, so-called confectionery products having a stirring blade that rotates while performing a planetary motion. Foaming machines, homogenizers generally used for emulsification and dispersion, stirrers such as cowless dissolvers, or continuous foaming machines such as Gaston County Co. in the United States and Stoke Co. in the Netherlands. It is possible to disperse and mix air into fine air bubbles by using a device that mechanically stirs while continuously feeding and the mixture of the resin-containing liquid.

In addition, because the capacity of the equipment for mechanical stirring is insufficient, the desired state of containing bubbles cannot be obtained, or the stability of bubbles in the resin liquid containing bubbles is improved. It is also possible to appropriately select and blend surface active materials called foam stabilizers and foaming agents. Such surfactants include higher fatty acids, modified higher fatty acids,
Alkali salts of higher fatty acids and the like can be used because they have a particularly high effect of enhancing the foamability of the water-dispersible resin-containing liquid and an effect of improving the stability of the dispersed and contained bubbles. There is no limitation on the selection of these, but it is natural to avoid using a material that may significantly impair the fluidity of the water-dispersed resin-containing mixed liquid or impair the coating workability. The amount of the surfactant such as the above-mentioned foam stabilizer and foaming agent is
The solid content of the surfactant is preferably 0 to 30 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the solid content of the water-dispersed resin liquid or the mixed liquid of the water-dispersed resin liquid and the pigment. Parts by weight. Even when the amount of the surfactant added exceeds 30 parts by weight, the effect is saturated, which is rather economically disadvantageous in many cases.

In the present invention, the bubble-containing state of the water-dispersible resin-containing liquid containing bubbles is not particularly limited, but preferably the volume ratio (foaming ratio) of the bubble-containing liquid to the stock solution is 1.
It 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 in the water-containing resin containing bubbles, and means that the resin film (wall) constituting the bubbles becomes thinner as the expansion ratio increases. As described above, when the resin film becomes thin, it may be difficult to maintain the strength of the obtained porous ink receiving layer at a sufficient level. In this respect, the expansion ratio and the water-dispersible resin-containing mixed liquid composition Attention should be paid to the balance with.

The coating method for forming the porous ink receiving layer on the support is not particularly limited, but for example, the Meyer bar method, the gravure roll method, the roll method,
It can be arbitrarily selected from known methods such as a reverse roll method, a blade method, a knife method, an air knife method, an extrusion method and a cast method.

As the sheet-like support used in the present invention, papers containing cellulose as a main component, coated papers, laminated papers and the like, as well as cloths such as woven cloths and non-woven cloths can be used. . 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. The better the heat insulation of these supports, the better the dot reproducibility and gradation reproducibility with the same applied energy, and the increase in recording density can be achieved. Further, the same density and recording quality can be achieved. It is also effective in energy saving because it requires less energy to obtain it. In addition, when paper or coated paper containing pulp as a main component is used as a support, there is an advantage that it can be particularly recycled.

The coating amount on the porous ink receiving layer support is such that the dry weight per 1 m ² on one side of the support is in the range of 2 to 40 g (2 to 40 g / m ² ). Is preferred. When the coating amount is less than 2 g / m ² , it often becomes difficult to sufficiently cover the surface roughness of the support, and an image receiving sheet having a proper smoothness cannot be obtained. In some cases, sufficient heat insulation and compression deformability may not be obtained. On the other hand, if it exceeds 40 g / m ² , the thickness of the porous ink-receiving layer becomes too large and the bonding strength in the porous ink-receiving layer decreases, so that when the image is formed, the ink-receiving In some cases, a trouble such as peeling of the layer occurs, and a good image cannot be formed.
Therefore, optimization of the coating amount of the porous ink receiving layer is
As with the optimization of the resin-containing liquid composition, it is natural to pay sufficient attention.

The sheet having the porous ink receiving layer of the present invention can show a good melt heat transfer image even when the resin solution containing bubbles is coated on a sheet-shaped 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 semi-dried or dried sheet is contacted with a mirror-finished heated or non-heated cast drum to improve its surface smoothness. You may let me. 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 may be deformed or destroyed,
The excellent melted 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 above smooth finish processing.

In producing the image-receiving sheet of the present invention, coating,
In processes such as drying and winding, the sheet itself may curl with its coated surface inside or outside. In this case, if the sheet is used after being cut into an image-forming sheet having a predetermined size, the sheet may not be normally fed to the thermal transfer printer, or the running property inside the printer may deteriorate. Trouble may occur. Further, the melt transfer recording method is a method in which a heat source is brought into contact with an ink ribbon and the dye component in the ribbon is transferred onto a recording sheet, so that the porous ink receiving layer, which is the image forming surface, and the support layer are heated. Due to the difference in shrinkage or the difference in expansion characteristics that accompanies the image receiving sheet, curling occurs inside the apparatus, and the above-mentioned trouble occurs. Due to such curling, an image is formed obliquely with respect to the normal paper surface direction, or wrinkles are likely to occur on the sheet inside the apparatus, and thus the ink ribbon and the image receiving sheet are not normally contacted, Ink transfer failure may occur, resulting in poor image quality.

In order to prevent various troubles caused by such curl, the difference in shrinkage characteristics or the difference in expansion characteristics between the porous ink receiving layer and the support layer due to heating should be minimized. Is desirable. Therefore, a curl prevention layer may be coated or laminated on the back surface of the sheet, that is, the surface opposite to the porous ink receiving layer. Material of this anti-curl layer, forming method, coating amount,
There is no limitation on the amount of lamination, etc., and optimization should be made by taking into consideration various factors such as the type and thickness of the support or the properties of the porous ink receiving layer, that is, material composition, expansion ratio, coating amount, etc. You can

Further, depending on the selection of the material of the support, when the obtained image receiving sheet travels in the printer, it is affected by various frictional forces due to the mechanism of the apparatus, and the influence of heating such as a decrease in humidity inside the apparatus is independent. In some cases or in combination, the image receiving sheet may be charged with static electricity. When a large number of images are continuously formed in such a state, the image forming surface of the image receiving sheet and the back surface of the next image receiving sheet are electrostatically adhered to each other and are difficult to peel off. In particular, since various plastic sheets or synthetic papers are inherently prone to being charged with static electricity, when these are used as a support, static electricity is generated during the sheeting process by cutting or during storage after processing. Therefore, it becomes difficult to remove the front and back of the sheet. As a matter of course, even when paper is used as the support, the above troubles can occur. It is extremely effective to form a so-called antistatic layer on the back surface of the image receiving sheet in order to prevent such troubles due to charging. Charging can also be achieved by using an antistatic material, or by reducing the coefficient of friction between the sheet back surface and the porous ink receiving layer. Therefore, the antistatic layer can be formed by appropriately selecting from a wide range of materials and methods as in the formation of the curl preventing layer.

The anti-curl layer and the antistatic layer can be separately formed on the back surface of the support to obtain desired performance, but the production process can be simplified, the production cost can be reduced, or the desired performance can be obtained. The purpose can be achieved by forming a single layer by appropriately selecting the material and the forming method as required, such as the functional level. 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.

[0033]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these. All "parts" in Examples and Comparative Examples represent the number of parts by weight based on the solid content of the water-dispersible resin.

Example 1 A resin mixture having a composition shown below (concentration of solid content: 28% by weight) was mixed with a stirrer (trademark: Kenmix Aiko PR).
O, manufactured by Aikosha Co., Ltd., using a stirring speed of 49
The foaming treatment was performed by stirring at 0 rpm for 7 minutes. The expansion ratio was 4.5 times. Resin mixture liquid composition Polyurethane resin: Water retention value 420 seconds (trademark: NeoRez R-9637, manufactured by Zeneca Corp.) 100 parts Higher fatty acid type foam stabilizer (trademark: SN foam 200, manufactured by San Nopco Co., Ltd.) 5 parts Viscosity control Agent: Polyvinyl alcohol (Trademark: PVA-124, manufactured by Kuraray Co., Ltd.) 15 parts Immediately after the foaming treatment of the air-dispersed water-dispersed resin mixture, an applicator bar is applied on the surface of woodfree paper having a weight of 75 g / m ² Was applied so that the coating amount (dry matter amount) would be 15 g / m ^2, and the coating was dried to form a porous ink receiving layer to prepare an image receiving sheet.

Example 2 In a resin mixture composition, a polyurethane resin (trademark: N
Instead of 100 parts of eoRez R-9637, manufactured by Zeneca Corporation, a styrene-acrylic copolymer resin (trademark:
KG-2010, manufactured by Arakawa Chemical Industry Co., Ltd., water retention value 85
An image receiving sheet was produced in the same manner as in Example 1 except that 100 parts of (second) was used.

Example 3 In a resin mixture solution composition, a polyurethane resin (trademark: N
Instead of 100 parts of eoRez R-9637, manufactured by Zeneca Corporation, SBR latex (trademark: L-1763,
An image receiving sheet was prepared in the same manner as in Example 1 except that 100 parts of Asahi Kasei Co., Ltd., water retention value 6 seconds) was used and stirring in the foaming treatment was carried out for 6 minutes.

Example 4 An image-receiving sheet was prepared in the same manner as in Example 1 except that the water-dispersed resin mixture containing bubbles having an expansion ratio of 1.5 was prepared by stirring for 2 minutes in the foaming treatment.

Example 5 The foaming ratio was 9.0 for 10 minutes with stirring in the foaming treatment.
An image-receiving sheet was produced in the same manner as in Example 1 except that a double-bubble-containing water-dispersed resin mixture was prepared.

Comparative Example 1 An image receiving sheet was produced in the same manner as in Example 1 except that the foaming treatment of the resin mixed liquid was omitted.

Comparative Example 2 A polyurethane resin (trademark: N
Instead of 100 parts of eoRez R-9637, manufactured by Zeneca Corporation, a polyurethane resin (trademark: NeoRez)
An image receiving sheet was produced in the same manner as in Example 1 except that 100 parts of R-9208 (manufactured by Zeneca Corporation, water retention value: 3 seconds) was used.

Comparative Example 3 In the resin mixture liquid composition, a polyurethane resin (trademark: N
Instead of 100 parts of eoRez R-9637, manufactured by Zeneca Corporation, SBR latex (trademark: L-1225,
An image receiving sheet was prepared in the same manner as in Example 1 except that 100 parts of Asahi Kasei Co., Ltd., water retention value 2 seconds) was used and stirring in the foaming treatment was carried out for 6 minutes.

Comparative Example 4 A polyurethane resin (trademark: N
Instead of 100 parts of eoRez R-9637, manufactured by Zeneca Corporation, a polyurethane resin (trademark: NeoRez)
R-972, manufactured by Zeneca Corporation, water retention value 480 seconds) 100
An image receiving sheet was produced in the same manner as in Example 1 except that the parts were used.

Comparative Example 5 Agitating in the foaming treatment was carried out for 12 minutes, and the expansion ratio was 12.
Except that a water-dispersed resin mixture liquid containing twice as many bubbles was prepared,
An image receiving sheet was produced in the same manner as in Example 1.

Test In each of the examples and comparative examples, the water retention value, the expansion ratio, the pore size of the porous ink receiving layer, and the transfer ink image were evaluated by the following methods. Table 1 shows these measurement and evaluation results. [Measurement of water retention value] Filter paper (trademark: ADVANT) pretreated under the conditions described in JIS P8111 (pretreatment of test paper)
EC No. 2. Toyo Roshi Kaisha Ltd. size 50 mm
Take 10 pieces on each corner, fold each four laps inward,
One of them was floated on a water-dispersible resin (20 ° C.) having a solid content concentration of 38% by weight placed in a petri dish. At the same time, 0.1 g of powdered potassium permanganate was sprinkled on the surface of the filter paper, and the powder was dispersed in a water-dispersible resin (particularly at the interface with the filter paper).
The water retention value was determined by measuring the time (seconds) until the water of the above was gradually sucked up, passed through the filter paper, and the powdery potassium permanganate was dissolved in red. The test was repeated 10 times in an environment of 20 ° C. and 65% relative humidity, and the average value was used as the water retention value (second) of the water-dispersible resin.

[Measurement of Foaming Ratio] The foaming ratio was determined by dividing the weight of 100 ml of the resin-containing liquid (stock solution) before the foaming treatment by the weight of 100 ml of the resin-containing liquid containing bubbles after the foaming treatment.

[Measurement of Pore Diameter] The pore diameter of 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 accurately determining the contour of the pores on the surface. Draw on a transparent film with a black pen etc., and further, drum scanner (Trademark: 2605 type drum scan densitometer, manufactured by Abe Design Co., Ltd.)
Then, the contour information of the pores was read optically 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 converted to the equivalent circle diameter based on the area within the contour of the pore obtained by image analysis. And displayed it.

[Recording Performance] The image-receiving sheet having the porous ink-receiving layer obtained in each of the above Examples and Comparative Examples was conditioned at 20 ° C. and a relative humidity of 65% for one day and then subjected to a thermal transfer color printer (trademark). : Trueprin
t2200, manufactured by Victor Company of Japan, Ltd .: originally an image forming apparatus of sublimation type transfer, but modified so as to also be capable of image formation by a melt transfer system), and an ink image was melt-transfer recorded on the surface thereof. The reflection density of the obtained ink transfer image was measured by a Macbeth reflection densitometer and visually evaluated as described below. In the following evaluation criteria, a value of ◯ or higher is good and suitable for practical use, but a value of Δ or lower is insufficient and not suitable for practical use. (1) Ink image formed with 17 gradations (black monochrome image)
About Macbeth reflection densitometer RD-914 (trademark)
Measure the reflection density for each applied energy using
The highest reflection density and gradation reproducibility were evaluated. Gradation reproducibility is ◎, ○, △, × in the order of good reproduction.
The grade was evaluated. (2) Dot reproducibility is 4 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 receiving layer. It was evaluated by. (3) The sharpness of the color image was observed and evaluated in four grades of ⊚, ◯, Δ, and × in order of goodness. (4) The peeled state was observed by observing the image formed on the receiving layer, and in the order of good ink without peeling, ○, △,
The evaluation was made in three stages of x. The results of these evaluations are shown in Table 1.

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[Table 1]

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EFFECTS OF THE INVENTION According to the present invention, it is possible to easily control the pore diameter of the surface of the receiving layer, and to put into practical use a melt transfer ink image-receiving sheet having a high recording density and being excellent in gradation reproducibility, dot reproducibility and color sharpness. It will be possible and will greatly contribute to the industrial world.

Claims (3)

[Claims] 1. A water-dispersible resin having a sheet-shaped support and a porous ink-receiving layer formed from a resin-containing liquid containing a water-dispersible resin as a main component on one surface of the support. Water retention value by the potassium permanganate method of 3 is solid concentration 3
In the range of 5 to 450 seconds at 8% by weight, and
The average pore diameter of the surface of the porous ink receiving layer is 0.5.
To 30 μm, a melt transfer type ink image receiving sheet. 2. The water-dispersible resin is at least one selected from polyurethane, styrene-acrylic copolymer, and styrene-butadiene copolymer.
The melt transfer type ink image-receiving sheet described above. 3. Foaming is carried out by mechanically stirring a resin-containing liquid containing a water-dispersible resin as a main component whose water retention value by the potassium permanganate method is in the range of 5 to 450 seconds at a solid concentration of 38% by weight. A resin-containing liquid in which a large number of fine bubbles having a ratio (volume ratio before and after foaming compared with a constant weight paint) of more than 1 and less than 10 is formed is applied onto one surface of a sheet-like support and dried. And the average pore diameter of the surface is 0.5 to 3
A method for producing a melt transfer type ink image-receiving sheet, which comprises forming a porous ink-receiving layer in the range of 0 μm.