JPH1035118A - Melt transfer type ink image receiving sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melt transfer type ink image receiving sheet wherein the pore size of an image receiving layer surface is controlled evenly, excelling in dot reproducibility, tonal reproducibility and color definition, having high recording density, and providing ink peeling-free image recording. SOLUTION: The melt transfer ink image receiving sheet has a sheet support, a porous ink image receiving layer having many tiny pores formed by giving mechanical agitation to a resin-containing liquid which contains at least one type of polyethylene glycol surface active agents whose main component is a resin and HLB value is 13 to 19.8 on one surface of the sheet support, applying and drying it. The ratio of the total area (open area) of open parts occupied by pores to the total surface area of the porous ink image receiving layer is in a range of 10 to 60%, and in the said open parts, the percentage of an area occupied by pores with a diameter of 0.5 to 20μm is in a range of 70 to 100%.

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 producing the same. More specifically, when the present invention is used in a fusion transfer type thermal transfer printer using a thermal head, a melt transfer type ink image receiving apparatus can obtain a print ink image having excellent gradation reproducibility and dot reproducibility as well as recording density. The present invention relates to a sheet and a method for manufacturing the sheet.

[0002]

2. Description of the Related Art A thermal fusion transfer recording system using a thermal transfer ink sheet and a thermal head is 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 sheet. However, in recent years, in order to obtain higher gradation reproducibility than before with the 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 the image receiving sheet, in full-color printing from low applied energy to high applied energy, the dot shape of the melt-transferred ink is faithfully reproduced. Is the important quality of the recorded image.

It is necessary to appropriately respond to the characteristics of the image receiving sheet in order to make the thermal transfer image full-color as described above. In other words, when uncoated paper for normal printing is used in the full-color hot-melt transfer method, 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. There is. Also, if the surface is too rough, the portion where the ink is not transferred, i.e., spills, or if the surface is too smooth, the anchoring effect of the ink does not work and the transferred ink is transferred to the ink ribbon. Dropping due to reverse transcription is likely to occur. Any of these causes a poor dot reproducibility. In addition to the decrease in recording density due to the poor dot reproducibility as described above, a decrease in recording density due to low ink absorbency of the molten ink 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 in order to improve the cushioning properties of the image receiving sheet (Japanese Patent Application Laid-Open No. 2-89690). Gazette, JP-A 64-
27996). However, the cushioning and heat insulating properties of the image receiving sheet obtained by this method are still insufficient.
When the hollow particles are dissolved in the organic solvent of the receiving layer, an organic solvent-resistant polymer may be used as an adhesive for the hollow particles, or a high organic solvent-resistant polymer may be formed on the layer containing the hollow particles. It is necessary to provide a molecular layer, and this necessity complicates the manufacturing process of the image receiving sheet and increases the cost.

[0005] As another attempt to solve the above problem, a sheet-like support mainly composed of plastic is provided on a sheet-like support.
There is an example in which a resin layer containing a component eluted in water is formed, and a water-soluble component is eluted and removed from the resin layer, thereby improving the ink receiving capacity of the image receiving sheet.
In this case, there is a drawback that a sufficient maximum density cannot be obtained, or the printed image has no gloss, and the quality required for the image receiving sheet has not been satisfied. 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-mentioned problems of the prior art and, when used in a thermal transfer color printer, provides a print ink image having excellent gradation reproducibility and dot reproducibility as well as recording density. It is an object of the present invention to provide a resulting melt transfer type ink image receiving sheet.

[0007]

The melt-transfer type ink-receiving sheet of the present invention comprises a sheet-like support, and a resin having a main component on one surface of the sheet-like support.
It has a large number of fine pores formed by applying and drying a mechanically stirred resin-containing liquid containing at least one selected from polyethylene glycol surfactants of 3 to 19.8. A ratio of the total area of the pores occupied by pores to the total surface area of the porous ink receiving layer (pore area ratio) is in the range of 10 to 60%. Further, in the opening portion, a ratio of an area occupied by pores having a diameter of 0.5 to 20 μm is in a range of 70 to 100%. The method for producing a melt transfer type ink image-receiving sheet according to the present invention is characterized in that the resin-containing liquid has a total solid content of 10 in the resin-containing liquid.
With respect to 0 parts by weight, 1 to 20 parts by weight of at least one selected from polyethylene glycol-based surfactants having an HLB value of 13 to 19.8 is added, and a number of fine bubbles are formed by mechanical stirring. A resin-containing liquid having a foaming magnification (ratio of the volume after foaming to the volume before foaming, as compared with a paint having a constant weight) of more than 1 to 10 times, is applied to one surface of the sheet-like support. To form a porous ink receiving layer, and the ratio of the total area of the pores occupied by pores to the total area of the porous ink receiving layer (open area ratio) is 10 to 60%. And the ratio of the area occupied by pores having a diameter of 0.5 to 20 μm in the opening portion is controlled to a range of 70 to 100%.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies to achieve the above object, the present inventor has selected a polyethylene glycol surfactant having an HLB value of 13 to 19.8 and added it to a resin-containing liquid. By applying mechanically stirring, applying a coating containing microbubbles, and drying to form a porous ink receiving layer with many micropores, it is possible to control the distribution of pore diameters very uniformly. And the ratio of the total area of the pores occupied by the pores to the total surface area of the porous ink receiving layer (pore area ratio) is 10
It has been found that an image receiving sheet having a pore size of 0.5 to 20 μm in a range of 70 to 100% can be obtained in the range of 60% to 60% and in the opening portion on the surface of the receiving layer. It has been found that, by using such an image receiving sheet, high-density recording with extremely excellent dot reproducibility, gradation reproducibility and color image clarity can be realized in recording by a fusion heat transfer printer, and the present invention has been completed. Was.

In the present invention, it is considered that the mechanism of developing the excellent molten ink transfer performance involves the physical characteristics such as the structural characteristics, heat insulation, and compression characteristics of the porous ink receiving layer and the image receiving sheet. Can be In particular, in terms of structural characteristics, since the surface of the porous ink receiving layer formed on the support has many fine holes, the porous ink receiving layer has a capability of absorbing molten ink by capillary force. Since many pores contained in the porous ink receiving layer communicate with each other (constituting open cells), the permeability of the molten ink into the porous ink receiving layer becomes good,
It is considered that high ink receiving capacity is exhibited. In this regard, it is important to control the open area ratio of the surface of the porous ink receiving layer formed on the image receiving sheet to an appropriate range.

In the present invention, it is important that the open area ratio of the surface of the porous ink receiving layer is in the range of 10 to 60%, preferably 30 to 60%. If the open area ratio is less than 10%, a sufficient maximum density cannot be obtained because the space for receiving the ink is insufficient. On the other hand, if it exceeds 60%, the film strength of the porous ink receiving layer becomes insufficient at the time of thermal transfer recording, the ink is liable to peel off, and the image quality of the recorded image tends to deteriorate. Here, the open area ratio means the ratio (%) of the area occupied by the open holes by the pores to the total area of the surface of the porous ink receiving layer.

Further, the pore diameter is related to the ability to capture the molten ink by the capillary phenomenon caused by the size (size). Generally, the smaller the pores, the greater the ability, and the gradation reproduction of the recorded image , Dot reproducibility and color clarity are good. However, if the pore size is too small, the space for receiving the ink is insufficient,
Rather, the image density and the like decrease. If the pore size is too large, the transfer ink will be buried in the pores, preventing good contact between the ink ribbon and the surface of the porous ink receiving layer, causing poor transfer or uneven transfer, and dot reproduction. A defect is caused and a good image cannot be formed. Fine pores with a diameter of 20 μm or less have excellent ability to capture the molten ink, so that in order to form a good image,
It is important to increase the proportion of pores having a diameter of 20 μm or less.

In the present invention, it is important that the ratio of the area occupied by pores having a diameter of 0.5 to 20 μm in the pores on the surface of the porous ink receiving layer is in the range of 70 to 100%, preferably 80 to 100%. When the ratio of the area occupied by the pores having a diameter of 0.5 to 20 μm in the opening portion is 70% or less, the tone reproducibility, dot reproducibility, and color clarity tend to decrease. Here, the ratio of the area occupied by pores having a diameter of 0.5 to 20 μm refers to the ratio (%) of the total area of pores having a diameter of 0.5 to 20 μm to the total area of all pores present on the surface of the porous ink receiving layer. )
Means The open area ratio, the pore diameter and the area ratio on the surface of the porous ink receiving layer can be determined by measuring with an optical microscope or a scanning electron microscope photograph and an image analyzer.

Conventionally, a resin containing liquid is mechanically agitated, and a bubble containing resin liquid containing a large number of fine bubbles is applied on one surface of a sheet-like support and dried to form a porous ink receiving layer. As a result, a porous ink receiving layer having an average pore diameter of about 5 to 30 μm is obtained, and these values are generally the average pore diameter by number average. Therefore, on the surface of the porous ink receiving layer, the diameter 20
The relationship between the ratio of the area occupied by pores of μm or less and the above-mentioned number average pore diameter can be considered as follows. In other words, even if the average pore diameter is the same, if there is a difference in the number of pores per unit area or the distribution of the average pore diameter,
The hole area ratio is different from the area ratio of pores having a diameter of 20 μm or less in the hole area. For example, if the average pore diameter is 1
Even if it is 0 μm, when the number of pores per unit area is small, the opening area ratio may be less than 10%. When the number of pores per unit area is large, the opening area ratio may be smaller. The rate can be as high as 60% or more. Further, even if the number average pore diameter is 10 μm, there is a wide distribution of pore diameters, and when the proportion of the area occupied by pores having a diameter of 20 μm or less is small, the pores having a diameter of 20 μm or less in the area of the opening portion are occupied. The area percentage can be less than 50%.

The pore area ratio, pore diameter and its area distribution on the surface of the receptor layer are determined by the composition of the resin-containing mixed liquid before the bubble formation / dispersion treatment, that is, the type of the material, the mixing ratio, the bubbles, the coating, After drying, the amount remaining as a component directly related to the film thickness in the porous ink receiving layer, or the expansion ratio, the coating method, etc., are often affected by various factors, so setting of appropriate conditions is often required. is necessary. Furthermore, the size of the pores on the surface of the porous ink receiving layer in the present invention is obtained by mechanical stirring, and is related to the size of the bubbles in the bubble-containing resin liquid, and the stability, and is generally in the resin-containing liquid. The smaller and more stable the bubbles, the smaller the pores on the surface of the ink receiving layer after coating and drying.

In the present invention, the bubbles in the resin-containing liquid produced by mechanical stirring are stabilized, and the resin-containing liquid is coated and dried. After coating and drying, the desired open area ratio and uniform pore size distribution are obtained. In order to obtain a porous ink receiving layer having
A polyethylene glycol surfactant having an LB value of 13 to 19.8 is added. Preferably, the HLB value is between 15 and
It is in the range of 19.8. A polyethylene glycol-based (also referred to as ethylene oxide-based) surfactant in which a hydrophobic group is bonded to polyethylene glycol has both a hydrophilic group portion and a hydrophobic group portion, and is used in the resin-containing liquid of the present invention. By doing so, it is possible to form uniform bubbles extremely efficiently. In addition, the high molecular weight polyethylene glycol-based surfactant acts as a barrier to prevent gas from passing from small bubbles to large bubbles, and has a high water retention due to its structure, and suppresses the drainage phenomenon due to the plateau effect. It is believed that it exerts a combined effect on improving foam stability.

Here, the HLB value indicates a measure of the hydrophilicity of the nonionic surfactant, and is generally calculated by the following equation. (HLB value) = (hydrophilicity of hydrophilic group) / (hydrophobicity of hydrophobic group) = (weight% of hydrophilic group) × (1/5) In the case of a polyethylene glycol-based surfactant, the weight of the polyethylene glycol portion If% is E, it is represented by the following equation. (HLB value) = E / 5 The HLB value of polyethylene glycol itself is 20,
The HLB value of the polyethylene glycol-based surfactant becomes smaller than 20 as the number of hydrophobic groups increases. Polyethylene glycol having an HLB value of 20 does not contain a hydrophobic group and has no surface active effect, so that the effect of improving the stability of bubbles is small. When polyethylene glycol having an HLB value of 20 is contained on the surface of the porous ink receiving layer, the compatibility with the ink is reduced, and poor dot reproducibility and a reduced recording density are likely to occur. On the other hand, a polyethylene glycol-based surfactant having an HLB value of less than 13 has a small bubble stabilizing effect since the amount of hydrophobic groups increases and the solubility in water decreases as described above.

The polyethylene glycol-based surfactant that can be used in the present invention is not particularly limited. For example, higher alcohol ethylene oxide adduct,
Alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polyhydric alcohol fatty acid ester ethylene oxide adduct, higher alkylamine ethylene oxide adduct, fatty acid amide ethylene oxide adduct, oil and fat ethylene oxide adduct, polypropylene glycol ethylene oxide adduct And the like are appropriately selected and used. As specific examples, F-220 (HLB, 19.6), IONET MS-1000 (HLB, 15.7), IONET MO-600 (HLB, 13.7) manufactured by Sanyo Chemical Industries, and the like are preferably used. These polyethylene glycol-based surfactants can be used alone or as a mixture of two or more, if necessary. The amount of the polyethylene glycol-based surfactant used is 10% of the total solid content in the resin-containing liquid.
0 parts by weight, preferably 1 to 20 parts by weight,
More preferably, it is 1 to 10 parts by weight. If the amount of the polyethylene glycol-based surfactant is less than 1 part by weight, the effect is not exhibited, and if the amount of the polyethylene glycol-based surfactant exceeds 20 parts by weight, the effect is saturated, and on the contrary, Economically disadvantaged.

In order to adjust the stability of the bubbles contained in the resin-containing liquid by mechanical stirring, an interface other than the polyethylene glycol-based surfactant specified in the present invention is used as long as the effects of the present invention are not impaired. Of course, it is also possible to use a material having an active action in combination. Generally, it is called a foam stabilizer (or a foaming agent), and for example, an anionic surfactant such as a higher fatty acid, a modified higher fatty acid, an alkali salt of a higher aliphatic acid, or an amine salt of a higher fatty acid is used. . Although there is no strict restriction on the selection, it is reasonable to avoid using a material that may significantly impair the fluidity of the resin-containing mixed liquid or impair coating workability. The amount of the foam stabilizer to be used is preferably 1 to 30 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the total solids in the resin-containing liquid. If the amount is more than 30 parts by weight, the effect is not only saturated but economically disadvantageous, but also the film strength of the receiving layer becomes insufficient and the recording image quality may be deteriorated.

In the present invention, a method for forming, containing, and dispersing bubbles in a resin-containing liquid (hereinafter referred to as a foaming method) is as follows.
For example, a foaming machine for so-called confectionery having a stirring blade rotating while carrying out planetary motion, a homomixer generally used for emulsification dispersion, a stirrer such as a Cowles dissolver, or a mixture of air and a resin-containing liquid in a closed system. A device capable of mechanically agitating while continuously feeding and dispersing air into fine bubbles, for example, a continuous foaming machine such as Gaston County of the United States and Stoke of the Netherlands can be used. There are no strict restrictions.

Although the bubble-containing state of the resin-containing mixed solution is not particularly limited, it is preferable that microbubbles having an average diameter of 0.5 to 20 μm are dispersed and mixed, more preferably, the average diameter is 0.1 μm. It is preferably in the range of 5 to 10 μm. The average bubble diameter of the resin-containing mixture is 0.5 to 2
When it is in the range of 0 μm, the aperture area ratio of the ink receiving sheet is generally 10 to 60%, and the diameter of the aperture in the aperture area is 0.1%.
The ratio of the area occupied by pores of 5 to 20 μm is 70 to 10
The range is 0%. 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, the porous ink receiving layer formed on the sheet-shaped support contains a resin and, if necessary, a pigment as main components. Such a porous ink receiving layer is formed by applying mechanical stirring to a liquid material containing a resin or a mixture of a resin and a pigment to form and disperse a large number of fine bubbles therein, and to support the resin liquid containing the bubbles. It can be formed by coating and drying on the body.

The water-soluble or water-dispersible (emulsifying) resins usable in the present invention include, for example, polyvinyl alcohols and derivatives thereof having various molecular weights and saponification degrees, starch, derivatives of starch (eg, oxidized starch). , Various modified starches such as cationized starch),
Cellulose derivatives such as methoxycellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide-acrylate copolymer, acrylamide-acrylate-methacrylate copolymer, styrene- Alkaline salt of maleic anhydride copolymer, polyacrylamide and its derivatives, water-soluble resins such as polyethylene glycol, polyvinyl acetate, polyurethane, styrene-butadiene copolymer (SBR latex), acrylonitrile-butadiene copolymer ( NBR latex), polyacrylate, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-vinyl acetate copolymer, styrene-butadiene-ac Le copolymer, water-dispersible resin of polyvinylidene chloride, furthermore glue, casein, soybean protein, gelatin, can be used such as sodium alginate, but is not limited thereto. These resins can be used alone or as a mixture of two or more, if necessary. Among the above resins, acrylamide-acrylate copolymer, acrylamide-acrylate-methacrylate copolymer, polyvinyl acetate, polyurethane, styrene-butadiene copolymer (SBR latex), etc. It is preferably used and a remarkable effect can be obtained by using the methylcellulose of the present invention.

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

Further, the porous resin coating film of the present invention comprises:
As can be inferred from the structure, it is difficult to say that the coating film strength is essentially strong, so if various pigments are blended, the coating film strength is further reduced, and trouble such as image peeling occurs as described above. It can be the cause. Therefore, when the porous ink receiving layer is formed by adding various pigments to the aqueous dispersion type resin-containing liquid, it is necessary to use an appropriate mixing ratio in consideration of the overall quality of the image receiving sheet. Is natural. A known viscosity modifier, dispersant, dye, water-proofing agent, lubricant, cross-linking agent, plasticizer, etc. are added as necessary to the liquid material containing the resin or the mixture of the resin and the pigment before the formation of bubbles. can do.

The coating amount of the porous ink receiving layer on the sheet-like support, that is, the coating amount, is 1% on one surface of the obtained support.
from the dry weight per m ² is 2 40g (2~40g / m
^It is preferable to be in the range of ² ). Coating amount is 2
When the amount is less than g / m ² , it is often difficult to sufficiently cover the surface roughness of the support, and an image-receiving sheet having a surface having appropriate smoothness cannot be obtained, or a sufficient level cannot be obtained. Insulation properties and compressive deformation may not 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 is reduced, and when the image is formed, the ink receiving layer becomes thin. In some cases, troubles such as peeling off occur, and a good image cannot be formed. Therefore, it is natural that the coating amount of the porous ink receiving layer should be adjusted with the same care as the adjustment of the composition of the resin-containing liquid.

In the present invention, the porous ink receiving layer is formed, for example, by incorporating a large number of fine bubbles into the above-mentioned water-dispersible resin liquid or a liquid mixture containing the water-dispersible resin and a pigment as main components, and forming a sheet-like support. It can be obtained by coating and drying on the body, but 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 water-dispersed resin-containing liquid containing bubbles is not particularly limited, but preferably the volume ratio of the bubble-containing liquid to the stock solution (hereinafter referred to as the expansion ratio) is more than 1 to 10 times. And more preferably 1
More than double and less than 5 times. That is, the expansion ratio is a scale indicating the bubble content in the bubble-containing water-dispersed resin-containing liquid,
When the expansion ratio is increased, it means that the thickness of the resin film (wall) constituting the bubbles is reduced. Further, when the expansion ratio is the same, it means that the resin film becomes thinner as the solid content concentration of the water-dispersed resin-containing mixed liquid 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. In this regard, the expansion ratio and the composition of the water-dispersed resin-containing mixed liquid Careful attention should be paid to the balance.

The coating method for forming the porous ink receiving layer on the support includes a Meyer bar method, a gravure roll method, a roll method, a reverse roll method, a blade method, a knife method, an air knife method, and an extrusion method. , And a known method such as a casting method.

The sheet having a porous ink-receiving layer of the present invention can show a good molten heat transfer image even when the bubble-containing resin liquid is applied to a sheet-like support and left dry, A machine calender composed of two or more rolls, or a super calender composed of a metal roll and a resin roll or a metal roll and a cotton roll as appropriate is used to form the porous ink receiving layer. By performing a finishing treatment, the surface smoothness can be further improved. 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. May be. However, when the above-mentioned smooth finishing treatment is performed under excessive pressure, 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 Since the pores on the surface of the ink 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 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 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,
In addition, since the amount of energy required for obtaining the recording quality is small, it is effective for energy saving. Further, when paper or coated paper containing pulp as a main component is used as a support, there is an advantage that recycling is particularly possible.

Further, when the bubble-containing water-dispersed resin liquid is applied onto the sheet-like support to produce the image-receiving sheet of the present invention, the steps of coating, drying, and winding up the sheet itself. Curling may occur with the coated surface inside or outside. In this case, if the sheet is used after being processed into an image forming sheet of a predetermined size by cutting, feeding to a thermal transfer printer may not be performed normally, or running properties inside the printer may be deteriorated. May cause trouble. Also, since the heat 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, it is necessary to heat the porous ink receiving layer, which is the image forming surface, and the support layer. Due to the accompanying difference in contraction or difference in expansion characteristics, the image 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 the sheet tends to be wrinkled inside the apparatus, so that the ink ribbon and the image receiving sheet are not normally contacted, Poor ink transfer may occur, resulting in poor image quality.

In order to prevent various troubles caused by such curling, it is necessary to minimize the difference in shrinkage characteristic or expansion characteristic between the porous ink receiving layer and the support layer due to heating. Is desirable. For this purpose, an anti-curl layer may be applied or laminated on the back surface of the sheet, that is, on the surface opposite to the porous ink receiving layer. The 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 in consideration of various factors such as the type and thickness of the support and the properties of the porous ink receiving layer, that is, material composition, expansion ratio, coating amount, etc. Can be.

Further, depending on the selection of the material of the support, when the obtained image receiving sheet travels inside the printer, it is subjected to various frictional forces due to the mechanism of the apparatus, and the influence of a decrease in humidity inside the apparatus due to heating, etc. is singly caused. In some cases, 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. In particular, since various types of plastic sheets or synthetic paper are inherently easily charged, when using them as a support,
In the process of forming a sheet by cutting or during storage after processing, the generation of static electricity makes it difficult to peel the front and back of the sheet. As a matter of course, even when paper is used as the support, the above-mentioned trouble 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 caused by charging. Charging can be achieved by using an antistatic material or by reducing the coefficient of friction between the back surface of the 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 anti-static layer can be individually formed on the back surface of the support to obtain the desired performance, but the production process can be simplified, the production cost can be reduced, or the desired performance can be reduced. By appropriately selecting a material and a forming method as necessary, such as the functional level of the above, the object can be achieved by forming a single layer. That is, it is 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.

[0033]

The present invention will be described more specifically with reference to the following examples. However, the scope of the present invention is not limited by these. In the following Examples and Comparative Examples, “parts” and “%” represent “parts by weight of solid content” and “% by weight” unless otherwise specified. Example 1 Resin mixture having the following composition (solids concentration 35%)
Was stirred at a stirring speed of 490 rpm for 4 minutes using a stirrer (trade name: KENMIX IKO PRO, manufactured by Aikosha Seisakusho) to perform a foaming treatment. The expansion ratio is 4.5
It was twice. Resin mixture liquid composition aqueous polyurethane resin (trademark: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo) 100 parts Higher fatty acid-based foam stabilizer (trademark: SN Foam 200, manufactured by San Nopco) 10 parts Thickener: carboxymethylcellulose sodium ( Trade mark: AG gum, manufactured by Daiichi Kogyo Seiyaku) 5 parts Polyethylene glycol surfactant: HLB, 19.6 (trademark: F-220, manufactured by Sanyo Chemical Industries) 5 parts Foaming treatment of the resin mixture of the above composition Immediately thereafter, a coating amount (dry matter amount) of 15 g / m ² was applied on the surface of a high quality paper of 75 g / m ² of rice tsubo using an applicator bar, dried, and dried to form a porous ink receiving layer. Was formed to produce an image receiving sheet.

Example 2 In a resin mixture composition, a polyethylene glycol-based surfactant (trade name: F-220, manufactured by Sanyo Chemical Industries, HL)
B, 19.6), except that a polyethylene glycol-based surfactant (trade name: Ionnet MS-1000, manufactured by Sanyo Chemical Industries, HLB, 15.7) was used instead of the image receiving sheet in the same manner as in Example 1. Was prepared.

Example 3 In a resin mixture composition, a polyethylene glycol-based surfactant (trade name: F-220, manufactured by Sanyo Chemical Industries, HL)
B, 19.6), except that a polyethylene glycol-based surfactant (trade name: Ionnet MS-600, manufactured by Sanyo Chemical Industries, HLB, 13.7) was used instead of B.19.6).
An image receiving sheet was produced in the same manner as described above.

Example 4 An image receiving sheet was prepared in the same manner as in Example 1 except that a resin mixture having the following composition (solid content: 35%) was used. Resin mixture liquid composition aqueous polyurethane resin (trademark: Adekabon Titer HUX-401, manufactured by Asahi Denka Kogyo) 100 parts Higher fatty acid-based foam stabilizer (trademark: SN Foam 200, manufactured by San Nopco) 10 parts Thickener: carboxymethylcellulose sodium ( Trademark: AG gum, manufactured by Daiichi Kogyo Seiyaku) 3.2 parts Polyethylene glycol surfactant: HLB, 19.6 (trademark: F-220, manufactured by Sanyo Chemical Industries) 18 parts

Example 5 An image receiving sheet was prepared in the same manner as in Example 1 except that a resin mixture having the following composition (solid content: 35%) was used. Resin mixture composition styrene-butadiene latex (trademark: L-1612, manufactured by Asahi Kasei Kogyo) 100 parts Higher fatty acid-based foam stabilizer (trademark: SN Foam 200, manufactured by San Nopco) 10 parts Thickener: sodium carboxymethylcellulose (trademark: AG) Gum, Daiichi Kogyo Seiyaku) 5 parts Polyethylene glycol surfactant: HLB, 19.6 (trademark: F-220, manufactured by Sanyo Chemical Industries) 2 parts

Example 6 The same procedure as in Example 1 was carried out except that a mixture having the same composition as in Example 1 was stirred with the above-mentioned stirrer for 1.5 minutes to prepare a bubble-containing resin mixture having an expansion ratio of 1.5. Thus, an image receiving sheet was produced.

Example 7 A mixture of the same composition as in Example 1 was stirred for 8 minutes with the above-mentioned stirrer to prepare a bubble-containing resin mixture having an expansion ratio of 9.0. An image receiving sheet was produced.

Example 8 In a resin mixture composition, a higher fatty acid-based foam stabilizer (trade name:
An image receiving sheet was produced in the same manner as in Example 1, except that the amount of SN Form 200 (manufactured by San Nopco) was changed to 5 parts.

Comparative Example 1 An image receiving sheet was prepared in the same manner as in Example 1 except that the foaming treatment of the resin mixture was omitted, and the coating and drying were performed on the surface of high quality paper.

Comparative Example 2 In a resin mixture composition, a polyethylene glycol-based surfactant (trade name: F-220, manufactured by Sanyo Chemical Industries, HL)
B, 19.6), except that a polyethylene glycol-based surfactant (trade name: Ionnet MO-400, manufactured by Sanyo Chemical Industries, HLB, 11.8) was used in place of B) (19.6).
An image receiving sheet was produced in the same manner as described above.

Comparative Example 3 In the composition of the resin mixture, a polyethylene glycol-based surfactant (trade name: F-220, manufactured by Sanyo Chemical Industries, HL)
B, 19.6), in the same manner as in Example 1 except that a polyethylene glycol-based surfactant (trade name: Ionnet DL-200, manufactured by Sanyo Chemical Industries, HLB, 6.6) was used instead of B19.6). Was prepared.

Comparative Example 4 A liquid mixture having the same composition as in Example 1 was stirred for 10 minutes with the above stirrer to prepare a bubble-containing resin mixed liquid having an expansion ratio of 12.0 times. An image receiving sheet was produced.

Comparative Example 5 In the composition of the resin mixture, a polyethylene glycol surfactant (trade name: F-220, manufactured by Sanyo Chemical Industries, HL)
B, 19.6) Instead of 5 parts, polyethylene glycol (trademark: PEG1000, manufactured by Sanyo Chemical Industries, HLB,
20.0) An image receiving sheet was produced in the same manner as in Example 1 except that 18 parts were used.

Comparative Example 6 In the composition of the resin mixture, a polyethylene glycol-based surfactant (trade name: F-220, manufactured by Sanyo Chemical Industries, HL)
B, 19.6) An image receiving sheet was produced in the same manner as in Example 1 except that 5 parts were removed.

Test In each of the above Examples and Comparative Examples, the following methods were used to measure the expansion ratio, the ratio of the opening area of the porous ink receiving layer, the pore size, and the evaluation of the transferred ink image. Table 1 shows the measurement and evaluation results. [Measurement of expansion ratio] Resin-containing liquid (stock solution) 1 before foaming treatment
The foaming ratio was determined by dividing the weight of 00 ml by the weight of 100 ml of the resin-containing liquid containing the foam after the foaming treatment. [Measuring method of pore area ratio, pore diameter and its ratio] The pore area ratio of the surface of the porous ink receiving layer, and the ratio of the area occupied by pores having a specific diameter are determined by a scanning electron microscope or an optical microscope. After taking a photograph of the surface of the receptor layer by using, a contour of pores on the surface 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)
III, manufactured by Nireco Corporation). The open area ratio is the ratio of the total area of the open area occupied by pores to the total surface area of the porous ink receiving layer surface,
It was calculated by the following equation. Perforated area ratio (%) = (total area of perforated portion occupied by pores) / (total surface area of porous ink receiving layer surface)
× 100 The ratio of the area occupied by pores having a diameter in the range of 0.5 to 20 μm in the area of the opening was calculated by the following equation. Ratio of area occupied by pores having a diameter of 0.5 to 20 μm (%)
= (Total area occupied by pores having a diameter of 0.5 to 20 μm) /
(Total area of open portion occupied by pores) x 10
0 Since the shape of the pores formed on the surface of the porous ink receiving layer is not necessarily a perfect circle, the pore diameter is determined to be a circle equivalent diameter based on the area within the contour of the pore obtained by image analysis. The pore diameter was indicated by conversion.

[Recording Performance] The image receiving sheets having the porous ink receiving layers obtained in the above Examples 1 to 8 and Comparative Examples 1 to 6 were 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 an image forming apparatus of the sublimation transfer type, but modified so as to be able to form an image of the melt transfer type, and melt-transfer-recorded the ink image on the surface thereof. The reflection density of the obtained ink transfer image was measured with a Macbeth reflection densitometer and evaluated visually as described below. (1) Ink image formed with 17 gradations (black monochrome image)
About Macbeth reflection densitometer RD-914 (trademark)
The reflection density is measured for each applied energy using
The maximum reflection density and gradation reproducibility were evaluated. The gradation reproducibility is 4 in the order of △, ○, Δ, × from the one that is reproduced well.
It was evaluated on a scale. (2) The dot reproducibility was evaluated by observing the dots of the ink transferred from the ink ribbon to the receiving layer, and in the order of さ れ, △, Δ, and ×, in order of good reproducibility in the same manner as the gradation reproducibility. Was evaluated. (3) The sharpness of the color image was observed and evaluated in four steps of ４, △, Δ, and × in order of good quality. (4) The peeled state was evaluated by observing the image formed on the ink receiving layer, and in order of good quality without ink peeling,
The evaluation was made in three stages of x. Table 1 shows the results of these evaluations. In the above evaluation criteria, a level of 以上 or more is suitable for practical use, but a level of △ or less is not suitable for practical use.

[0049]

[Table 1]

[0050]

According to the present invention, the bubbles of the resin-containing liquid are efficiently formed, the pore diameter on the surface of the receiving layer is controlled uniformly, and the dot reproducibility, gradation reproducibility and color clarity of the melt-transferred ink image are obtained. This makes it possible to practically use a fused transfer ink image-receiving sheet which is excellent in image quality, obtains a high recording density, and has no ink peeling, and greatly contributes to the industry.

Claims (2)

[Claims] 1. A sheet-like support having a resin as a main component and an HLB value of 13 on one surface of the sheet-like support.
It has a large number of fine pores formed by mechanically stirring and applying and drying a resin-containing liquid containing at least one selected from polyethylene glycol surfactants of 19.8 to 19.8. A porous ink receiving layer, wherein the ratio of the total area of the open portions occupied by the pores (open area ratio) to the total surface area of the porous ink receiving layer is in the range of 10 to 60%, and Wherein the ratio of the area occupied by pores having a diameter of 0.5 to 20 [mu] m in the opening portion is in the range of 70 to 100%. 2. The resin-containing liquid contains at least one selected from polyethylene glycol surfactants having an HLB value of 13 to 19.8 based on 100 parts by weight of the total solids in the resin-containing liquid. The foaming ratio (volume after foaming and volume before foaming, compared with a constant weight of paint) of the paint containing a large number of fine bubbles by mechanical stirring is increased by 1%. A resin-containing liquid, which is not more than 10 times or more, is coated on one surface of the sheet-like support and dried to form a porous ink receiving layer, and an opening occupied by pores with respect to the entire area of the porous ink receiving layer. The ratio of the total area of the holes (opening area ratio) is in the range of 10 to 60%, and
A method for producing a melt transfer type ink image receiving sheet, wherein a ratio of an area occupied by pores having a diameter of 0.5 to 20 μm in the opening portion is controlled in a range of 70 to 100%.