JPH05318947A - Image receiving paper for thermal transfer recording - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to an image-receiving paper used in a thermal transfer recording method of a heat-melt ink type. (EN) Provided is an image-receiving paper for thermal transfer recording, which can obtain a recorded image with high image quality and which is also excellent in recording suitability for high-speed recording and full-color recording. [Structure] An image receiving layer for receiving heat-meltable ink is provided on a support, and the image receiving layer is in the presence of a hydrophilic medium containing a porous pigment having an apparent specific gravity of 0.10 to 0.50 g / cm ³ and a water-soluble protective colloid agent. The coating composition is mainly composed of a calcium carbonate pigment surface-treated with a disperser using a medium and an adhesive, and the recording image surface obtained on the surface of the image receiving layer has a 60 ° specular gloss of 45. Adjust so that it is at least%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image receiving paper used in a copying machine, a printer, a facsimile or the like utilizing a heat transfer recording system of a hot melt ink type, and particularly excellent in ink acceptability in full color heat transfer recording and recording image. Relates to an image-receiving paper for thermal transfer recording having high image quality.

[0002]

2. Description of the Related Art With the progress of office automation in recent years, copying machines and printers using various recording systems such as electrophotographic systems and thermal transfer recording systems are provided with CAD / C according to their respective applications.
It is also widely used in AM and the like. A colored coloring material is used for this image formation, and the coloring material is usually melted, evaporated and sublimated and transferred onto a recording medium such as paper or a film sheet, and the recorded image is formed by adhesion, adsorption or dyeing. It has gained.

In this type of recording system, an ink ribbon having a heat-fusible ink layer made of a color material is melted by heat generated by a thermal head, and the color material is transferred to a recording paper to obtain a recorded image. A molten ink type thermal transfer recording system has recently been drawing attention. This system is characterized in that plain paper can be used as a recording medium.

However, in this thermal transfer recording system as well as other recording systems, full color recording, high speed recording, clear image recording,
The demand for higher resolution has increased, and plain paper is no longer satisfactory. For example, in the case of performing single-color or multi-color recording with a color thermal transfer printer or the like, a color head such as yellow, magenta, cyan, and black, an ink ribbon containing waxes or resins, and recording paper are combined and applied by a thermal head for recording. A transfer image is formed on the paper. In this case, since the inks of the respective colors are overlapped with each other, if plain paper is used as the recording paper, defects such as transfer unevenness and dot omission are likely to occur due to the smoothness of the image receiving layer surface and the ink acceptability. ..

For this reason, many proposals have been made for improving the smoothness of the surface of the image receiving layer. For example, Beck smoothing is specified (Japanese Patent Laid-Open Nos. 59-133092 and 59-18789).
2) those provided with a thermal transfer image-receiving layer containing a specific pigment or binder (JP-A-57-182487, 59-182787, 60)
-11489, 60-110492, 60-192690, 61-21728
9, ibid. 61-286187, ibid. 63-21185) and the like. However, in the case of these conventional methods, although an improvement effect is recognized to some extent, due to transfer unevenness or color misregistration in the overlapping portion of the color inks during multicolor recording, or missing transfer ink dots or poor dot shape reproducibility. ,
The deterioration of image sharpness has not been completely resolved. Therefore, it is not enough to simply enhance the calendering process to improve smoothness, or to add a specific pigment or binder to the thermal transfer image-receiving layer. The reality is that an image-receiving paper for thermal transfer recording, which is excellent in printing quality and produces a high-quality recorded image, has not yet been obtained.

With the widespread use of full-color recording, there has been an increasing demand for a thermal transfer recording image receiving paper which can express a sharp image with a high image close to a photographic print image as a recording medium. Speaking of image receiving paper, not only can thermal transfer recording suitability such as ink acceptance be improved and general paper quality such as whiteness and white paper glossiness be improved, but improvement in glossiness (ink gloss) of the recorded image surface is also a required quality. It is pointed out as one.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a heat-melt ink type image-receiving paper for thermal transfer recording, which is particularly excellent in ink transfer acceptability, reproducibility, fixability, gradation and sharpness.
Since it has excellent smoothness, there is no transfer unevenness or missing dots,
Further, it provides an image-receiving paper for thermal transfer recording which has excellent glossiness on the white paper surface and the recorded image surface, can obtain a high-quality and high-quality recorded image, and has excellent recording suitability for full-color recording as well as high-speed recording. To do.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a thermal transfer recording image-receiving paper having a support and an image-receiving layer for receiving a heat-meltable ink, wherein the image-receiving layer contains the following pigments and adhesives as main components. For thermal transfer recording, characterized in that the glossiness (60 degree specular glossiness according to JIS-Z-8741) of the recorded image surface formed on the image receiving layer surface is 45% or more. Porous pigment with an apparent specific gravity (JIS-K-6220) of 0.10 to 0.50 g / cm ^{3 on} an image receiving paper Surface activated by a disperser using a medium in the presence of a hydrophilic medium containing a water-soluble protective colloid agent It is a treated calcium carbonate pigment.

[0009]

In such a situation, the present inventors have particularly improved the adhesion between the ink ribbon and the recording image receiving surface, are excellent in the ink receiving property, have no transfer unevenness or dot omission, and have high image quality and high quality. In order to obtain a thermal transfer recording image receiving paper, earnest studies were conducted. As a result, a coating composition containing calcium carbonate treated by a specific method as a pigment, a specific porous pigment and an adhesive as a main component was applied on a support to form an image receiving layer, and the transfer ink was received. By adjusting the glossiness of the recorded image surface obtained as described above to be more than a specific value, it was found that, by the synergistic effect of these conditions, a remarkable effect that cannot be predicted from the known art can be obtained, and finally, The present invention has been completed.

Calcium carbonate for industrial use is roughly classified into heavy calcium carbonate obtained by physically crushing natural limestone and light calcium carbonate obtained by synthesizing by a chemical method. The mold is classified into a calcite type, an aragonite type and a vaterite type.
In the paper manufacturing industry, these calcium carbonates are widely used as fillers or pigments. Further, as a method for producing light calcium carbonate, there are a carbon dioxide gas compounding method in which carbon dioxide gas is blown into lime milk to react, and a carbonate solution compounding method obtained by reacting a carbonate with a calcium chloride aqueous solution or the like. The former carbon dioxide compound method is often adopted.

Originally, calcium carbonate has a very strong cohesive force between particles. Among them, calcium carbonate that has undergone a drying step forms agglomerates by binding a large number of each particle, and is usually non-uniform. Often exhibits a secondary particle size distribution. In particular, this tendency is remarkable in the light calcium carbonate obtained by synthesis by a chemical method. Therefore, if calcium carbonate that has been subjected to these drying steps is used as an agglomerate, it causes transfer unevenness and dot omission during recording, and obtains a high quality thermal transfer recording image receiving paper excellent in transferability and reproducibility. I can't.

In the thermal transfer recording image-receiving paper of the present invention, it is preferable to use calcium carbonate obtained by surface activation treatment with a dispersing machine using a medium in the presence of a hydrophilic medium containing a water-soluble protective colloid agent. It is a feature of. The calcium carbonate obtained by this method is dramatically improved in the wettability between the particle surface and the aqueous medium, so that sufficient adhesion is imparted with a small amount of binder, and as a result, the original calcium carbonate particles are obtained. Can exhibit the excellent characteristics of, the excellent transfer ink acceptability and the sharpness of the image, the high gloss of the recorded image surface (ink gloss), and the uniform and smooth white paper gloss. To obtain an image receiving layer having

The surface activation treatment of the present invention is carried out by a disperser using a medium, and examples of the disperser include stirring tank type mills such as attritors and sentry mills, sand grinders, dyno mills, grain mills, Apparatuses such as a flow tube type mill such as a pearl mill and a matter mill, and an annular type continuous wet stirring mill such as a conical ball mill can be preferably used.

Examples of media used for dispersion include natural or synthetic fine particles such as flint stone, Ottawa sand, steel balls, alumina balls, zircon beads, and glass beads. Then, these media are filled in a container, and while mechanically stirring through a stirring blade of an arbitrary shape, the calcium carbonate dispersion liquid is then put into this container and passed once or multiple times to make the surface active. Processing is performed. In addition, in performing the surface activation treatment, the calcium carbonate is inevitably pulverized,
Over-grinding should be avoided and for that,
The average particle size of the media is preferably 0.1 mm or more. On the other hand, if it exceeds 5 mm, the surface activation treatment may be insufficient, which is not preferable. Therefore, the average particle size of the media is 0.1 to 5 mm, more preferably 0.1.
It is desirable to select and use one having a thickness of 25 to 5 mm.

Examples of the water-soluble protective colloid agent used in the present invention include saccharoses such as cation-modified starch and carboxy-modified starch, proteins such as gelatin, albumin, casein and soybean protein, and cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose. , Natural or semi-synthetic polymer compounds such as agar, sodium alginate, gum arabic; polyvinyl alcohol, polyvinylpyrrolidone, poly (meth) acrylamide, poly (meth) acrylic acid and its copolymers, maleic anhydride copolymer salts, And an addition polymerization type synthetic polymer compound such as oligomers or polymers having water solubility and optionally containing an anionic group and / or a cationic group; polyethyleneimine resin, polyamide resin, polyamine resin, polyamide epichloro Dorin resin, polyamine epichlorohydrin resin can be suitably selected from condensed synthetic polymer compound such as polymer compounds such as dicyandiamide resin.

The amount of the water-soluble protective colloid agent used is appropriately selected in consideration of economical efficiency, workability, etc., but is generally 0.1 part by weight or more, more preferably 0.5 to 50 parts by weight with respect to calcium carbonate. Use within the range of a part. In addition, other various pigments, various auxiliaries such as dispersants, or binders may be used as needed, as long as the effects of the present invention are not impaired. The solid concentration of the calcium carbonate dispersion is arbitrarily selected within the range of about 25 to 85% by weight.

The hydrophilic medium referred to in the present invention means a dispersion medium mainly composed of water, and alcohols,
Water-soluble solvents such as ketones and ethyl acetate may be partially contained.

Further, it is desirable that the surface-activated calcium carbonate of the present invention maintains an appropriate particle morphology so that the conditions of the following formulas [1] and [2] are simultaneously satisfied. By maintaining the particle morphology in such a specific range, a high degree of gloss and smoothness can be imparted, and more desirable effects desired by the present invention can be obtained. 1.2 ≤ d / D ≤ 6.0 [1] 0.1 ≤ d ≤ 1.5 [2] d: Average particle size (μm) by Sedigraph X-ray transmission type particle size distribution measurement method D: BET Based on specific surface area by specific surface area measurement method Average particle size (μm)

Here, the average particle diameter d is the particle diameter when the cumulative weight measured in the water dispersion system reaches 50%, that is, the weight average particle diameter. The agglomerates that became secondary particles were measured as the particle diameter as if they were primary particles. Therefore, d
Is correctly interpreted as the average secondary particle size. (Hereinafter, d is referred to as secondary particle size)

On the other hand, the average particle diameter D calculated by the theoretical calculation formula based on the value measured by the BET specific surface area measuring method is
As described above, it cannot be changed by surface activation, and can be approximately defined as the original particle size of calcium carbonate, that is, the primary particle size. (After that, D
Is called the primary particle size)

Incidentally, in the present invention, when the secondary particle diameter d of the surface-activated calcium carbonate is less than 0.1 μm, the image receiving layer becomes dense, the ink receptivity is deteriorated, and the dot reproducibility is lowered. .. On the other hand, if it exceeds 1.5 μm, not only the coating suitability of the coating liquid for forming the image receiving layer is deteriorated, but also the image receiving layer surface having excellent smoothness cannot be obtained, which may cause transfer unevenness or dot dropout. Become. Further, the glossiness of white paper becomes difficult to develop, and a high quality image receiving paper cannot be obtained. Further, the frictional resistance tends to increase, the running property of the paper during recording tends to deteriorate, and this is not preferable because it causes color misregistration of a recorded image, especially in the case of color recording in which multiple color inks are overprinted. Therefore, it is desirable that d is in the range of 0.1 to 1.5 μm, more preferably 0.12 to 1.2 μm.

When the ratio of the secondary particle diameter d to the primary particle diameter D (hereinafter referred to as d / D value) exceeds 6.0, the surface-activated calcium carbonate appears to form relatively large aggregates. As a result, a uniform and smooth image-receiving layer cannot be obtained, resulting in uneven transfer, resulting in deterioration of image quality. On the other hand, the value of d / D is 1.2
When the individual particles are almost completely present in the state of primary particles, the calcium carbonate, which originally has a very strong cohesive force between the primary particles, is subjected to surface activation treatment by a disperser, for example. At this time, it is not preferable to intentionally separate it into such a state and to over-pulverize it because not only the characteristics of calcium carbonate desired by the present invention are lost, but also uneconomical. Therefore, the value of d / D is 1.2 to 6.0
, And more preferably in the range of 1.5 to 5.0.

The shape of calcium carbonate is not particularly limited, and, for example, an amorphous shape, a spindle shape, a needle shape, a prism shape, a column shape, a hexagonal column shape, a plate shape, a rectangular parallelepiped shape, or the like can be used. Among these, light calcium carbonate having a spindle shape, a needle shape, a prismatic shape, a columnar shape, and a hexagonal columnar shape having a major axis of 0.3 to 6 μm and a minor axis of 0.02 to 0.6 μm is more preferably used. The crystal structure of calcium carbonate and the manufacturing method thereof are not particularly limited, and for example, in the crystal structure, any of calcite type, aragonite type and vaterite type can be used.

The porous pigment used as the second feature of the present invention has a large amount of air contained in its particles, and by virtue of such a pigment being conveniently contained in the image receiving layer, Appropriate voids and cushioning properties can be provided. Therefore, the heat insulating properties of the image receiving layer act efficiently so that the heat from the thermal head can be stored on the surface of the image receiving layer appropriately. As a result, the receptivity of the transfer ink and the sharpness of the image are more remarkably improved, and further, the effect of improving the transfer unevenness and the dot omission is excellent, and the quality characteristics as the image receiving paper for thermal transfer recording are dramatically improved. Is.

The porous pigment has an apparent specific gravity (hereinafter simply referred to as "apparent specific gravity") in accordance with JIS-K-6220 of 0.10 to
It is not particularly limited as long as it is 0.50 g / cm ³ , and examples thereof include diatomaceous earth, calcined diatomaceous earth, flux calcined diatomaceous earth, calcined kaolin, zeolite, white carbon, fine particulate amorphous silica, magnesium aluminosilicate, fine particulate Examples thereof include calcium silicate, fine particle alumina, fine particle titanium oxide, fine particle magnesium carbonate, and fine particle light calcium carbonate. As a method of measuring the apparent specific gravity of the pigment, for example, the “bulk” defined in JIS-K-5101 is measured to determine the bulk specific gravity or bulk density (ml / g) of the apparent specific gravity (g / cm ³ ). There is also a method of converting to. However, as a result of researches by the present inventors, the thermal transfer of the present invention, such as the one obtained by applying a coating composition containing a porous pigment to form an image receiving layer, or further smoothing the paper through a pressure nip. In the case of a recording image-receiving paper, the value of the apparent specific gravity measured in a dense state of the pigment by applying a constant load specified in JIS-K-6220, is the effect desired by the present invention. It has been found to have a higher correlation with.

Incidentally, among the porous pigments, the apparent specific gravity is
When it exceeds 0.50 g / cm ³ , the characteristics of the porous pigment are reduced by half, the voids in the image receiving layer are reduced, the structure becomes dense, and the heat insulating efficiency of the image receiving layer sharply decreases. As a result, the receptivity and fixability of the transfer ink are poor, and it is not possible to obtain the image receiving paper for thermal transfer recording which is excellent in image quality and is free from uneven transfer and missing dots which are desired in the present invention. On the other hand, in the case of a porous pigment of less than 0.10 g / cm ³ , the voids in the image receiving layer increase and the heat insulating effect becomes higher than necessary, so that the heat of the thermal head is hard to cool on the surface of the image receiving layer and the heat is accumulated. As a result, bleeding of the transfer ink and bridging phenomenon are induced and the image quality deteriorates. Also, since the strength of the image receiving layer surface becomes extremely weak,
When the ink ribbon and recording paper are separated during recording,
The surface of the image receiving layer rolls up together with the transfer ink, resulting in loss of dots and deterioration of image quality. In particular, it becomes difficult to support recording such as speeding up and colorization for multicolor printing. Therefore, the apparent specific gravity is 0.10 to 0.50 g / cm ³ , more preferably 0.12 to 0.45 g / cm ³ , and even more preferably 0.15 to 0.
It is important that the range is 40 g / cm ³ .

In the present invention, the combined ratio of the specific calcium carbonate and the specific porous pigment is 5 to 80 parts by weight, more preferably 100 parts by weight of calcium carbonate.
It is desirable to use the porous pigment in the range of 10 to 70 parts by weight. Incidentally, if the combined use ratio of the porous pigment exceeds 80 parts by weight, the effect of manifesting the glossiness is remarkably reduced. In addition, the strength of the surface of the image receiving layer becomes extremely weak, resulting in defective transfer dots and easy generation of paper dust, which causes remarkable deterioration of image quality, which is not preferable. On the other hand, when the amount is less than 5 parts by weight, the above-mentioned characteristics of the porous pigment cannot be imparted to the image receiving layer, and the desired effect of the present invention cannot be obtained. In addition, in the surface treatment of calcium carbonate,
It is also possible to pre-mix calcium carbonate and the porous pigment for treatment.

The third feature of the present invention is JIS-Z-8741 of the recorded image surface obtained by transferring the heat-meltable ink to the surface of the image receiving layer.
60 degree specular gloss [Gs (60 °)] of 45% or more,
More preferably, it is adjusted to 50% or more to obtain an image-receiving paper for thermal transfer recording capable of expressing a recorded image with high ink gloss. In the past, in order to obtain such a recorded image surface with high ink gloss, it has been said that the characteristics of the heat-meltable ink and the design characteristics of the model such as a printer are largely responsible. However, as a result of earnest studies by the present inventors, by providing an image receiving layer containing calcium carbonate obtained by processing by the specific method of the present invention and a specific porous pigment as main components, the Gs of the recorded image surface is It was possible to adjust (60 °) to be 45% or more, and it was possible for the first time to find a thermal transfer recording image receiving paper having excellent quality characteristics desired by the present invention. The term "recorded image surface" as used in the present invention means a solid or multicolor solid recording surface obtained by recording by the hot melt ink type thermal transfer recording method.

Incidentally, in a general image-receiving paper for thermal transfer recording, a method has been adopted in which the image-receiving layer has a porous structure and a melted transfer ink is permeated into the image-receiving layer to enhance the acceptability and fixing property of the ink. Therefore, most of the obtained recorded images have no shiny or dull appearance and their Gs (60 °) is less than 45%. On the other hand, if the image receiving layer is made a dense layer to suppress the permeation of the transferred ink, the ink remains on the surface layer of the image receiving layer and the ink gloss of the recorded image portion is relatively high, but the ink acceptability and Since the fixing property is poor, the recorded image has many transfer irregularities and missing dots, and the image quality is extremely deteriorated. Therefore, even if the appearance quality of the image receiving paper such as the whiteness and the glossiness of the white paper is excellent, the present situation is that the image receiving paper for thermal transfer recording excellent in the quality characteristics desired by the present invention has not been obtained.

In addition to the specific calcium carbonate of the present invention and the porous pigment, other pigments may be used in the coating composition, if necessary, within a range that does not impair the desired effects of the present invention. .. As the pigment in this case, various pigments used for general coated paper, for example, kaolin, deramikarin,
Mineral pigments such as aluminum hydroxide, satin white, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, zinc carbonate, alumina, magnesium oxide, magnesium carbonate, silica, bentonite, zeolite, sericite and polystyrene. resin,
Examples thereof include fine particles of urea resin, melamine resin, acrylic resin, benzoguanamine resin and the like, fine hollow particles and other organic pigments.

The coating composition is prepared by including an adhesive, and the type of the adhesive refers to a water-soluble and / or water-dispersible polymer compound, for example, cationic starch,
Amphoteric starch, oxidized starch, enzyme-modified starch, thermochemically modified starch,
Starches such as esterified starch and etherified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, natural or semi-synthetic polymer compounds such as gelatin, casein, soybean protein and natural rubber; polyvinyl alcohol, isoprene, neoprene, polybutadiene, etc. Polydiene, polybutene, polyisobutylene, polypropylene, polyalkene such as polyethylene, vinyl halide, vinyl acetate, styrene, (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylamide, methyl vinyl ether Polymers and copolymers, styrene / butadiene-based, methyl methacrylate / butadiene-based synthetic rubber latex, polyurethane resin, polyester resin, polyamide resin, olefin / maleic anhydride Resins, synthetic polymer compounds such as melamine resins and the like. Among these, one kind or two or more kinds are appropriately selected and used according to the quality target of the image receiving paper for thermal transfer recording. Among these adhesives, polyvinyl alcohol is particularly excellent in the effect of improving the dispersion stability of the pigment, and is also excellent in the fixability of the transfer ink and the reproducibility of the dot shape, and moreover, it is possible to perform multicolor overprinting. Since the color reproducibility at the time is good, it is possible to obtain an image-receiving paper for thermal transfer recording which is free from color misalignment and is superior in gradation.

The compounding ratio of the adhesive is 1 to 50 parts by weight, more preferably 2 to 30 parts by weight, based on 100 parts by weight of the pigment. Incidentally, when the amount is less than 1 part by weight, the adhesive strength of the image receiving layer is lowered, so that paper dust is generated to adversely affect the image quality, and the aptitude as a printing paper is lost. On the other hand, if it exceeds 50 parts by weight, the properties of the specific calcium carbonate and the porous pigment used in the present invention cannot be sufficiently exhibited, so that the ink acceptability and fixing property are extremely lowered, and the stickiness of the image-receiving paper is reduced. It is not preferable because it may cause blocking due to the ink and defective dot reproducibility due to ink bleeding.

In the aqueous coating liquid, in addition to these, various auxiliaries such as a surfactant, a pH adjusting agent, a viscosity adjusting agent, a softening agent, a glossing agent, waxes, a dispersing agent, a flow modifier, and a conductive agent. Anti-static agent, stabilizer, antistatic agent, cross-linking agent, sizing agent,
A fluorescent whitening agent, a colorant, an ultraviolet absorber, an antifoaming agent, a water resistant agent, a plasticizer, a lubricant, an antiseptic, a perfume and the like can be appropriately used if necessary.

Regarding the coating amount of the coating liquid thus obtained,
It is selected according to the intended use of the image-receiving paper by obtaining the specific range of the present invention, but in general, a dry weight of 1 to 20 g / m ² per side is suitable. As a coating method for forming an image receiving layer, generally known publicly-used coating equipment, for example, blade coater, air knife coater, roll coater, reverse roll coater, bar coater, curtain coater, die slot coater, gravure coater, champlex coater, brush. A coater, a two-roll or metering blade type size press coater, a bill blade coater, a short dwell coater, a gate roll coater, and the like are appropriately used. These devices are used in conventional manner as on-machine coaters or off-machine coaters.

In forming the image receiving layer, 1
It is also possible to have a layer, or a multilayer structure of two or more layers if necessary. In the case of a multi-layer structure, each coating liquid does not have to be the same, and may be appropriately adjusted and blended according to a required quality level, and is not particularly limited. It is also possible to provide a synthetic resin layer, a coating layer composed of a pigment and an adhesive, an antistatic layer, etc. on the back surface of the support to prevent curling, impart printability, and paper feedability. Further, the back surface of the support may be subjected to various kinds of processing, for example, post-processing such as adhesion, magnetism, flame retardancy, heat resistance, water resistance, oil resistance, anti-slip, so that it may be used with added suitability for use.

The thus-prepared image-receiving paper for thermal transfer recording is subjected to smoothing treatment in a usual drying process or surface treatment process to obtain a white paper glossiness (JIS-P-8142: 75-degree specular glossiness) on the surface of the image-receiving layer. Is 40% or more, more preferably 45% or more, and the whiteness (JIS-P-8123: Hunter reflectance meter) is 75% or more, more preferably 80% or more, and the water content is 3%.
Is adjusted to about 10 to 10% by weight, and more preferably about 4 to 8% by weight.

When the smoothing treatment is performed, the above-mentioned quality is satisfied, and at the same time, the ten-point average roughness of JIS B0601 on the surface of the image receiving paper is 3 to 20 μm, and more preferably 5 to 5.
By adjusting the thickness within the range of 18 μm, a higher quality recorded image desired by the present invention can be obtained. By the way, the ten-point average roughness of the image receiving paper surface is 20 μm.
When it exceeds the range, the smoothness of the paper is inferior and the high-quality recorded image desired by the present invention cannot be obtained. Further, since the frictional resistance becomes large, the running property of the paper at the time of recording is deteriorated, which causes a color shift of a recorded image in the case of color recording. On the other hand, 3μ
If the smoothness of the surface of the image receiving paper is increased to less than m, the ink acceptability itself is not bad, but the dot diameter of the ink is too thin, causing color misregistration and uneven shading, resulting in poor color reproducibility. Becomes In addition, the fixing property of the ink is inferior, which causes deterioration of image quality due to loss of ink dots and rubbing stains.

The ten-point average roughness specified here is the universal surface profilometer SE-3C (manufactured by Kosaka Laboratory Ltd.).
Standard length of 8 according to the method specified in JIS-B-0601
It was measured in mm. In this surface roughness measuring method, the vertical movement of the stylus is converted into an electrical quantity, and the unevenness of the paper surface, that is, the smoothness is read. Therefore, it is possible that the air permeability of the paper may affect the fine roughness of the paper surface, which was considered difficult with measuring equipment such as Beck's smoothness meter and Parker print surf, which are general air leak type smoothness measuring tools. It is possible to perform accurate measurement without any problem, and according to the detailed examination results of the present inventors,
Rather than the value of the center line average roughness obtained by cutting off the waviness of the surface of the image receiving paper, the measured value of this ten-point average roughness may be highly correlated with the effect of the smoothing treatment desired by the present invention. It became clear.

Further, when smoothing the image-receiving paper for thermal transfer recording, it is carried out by a smoothing device such as an ordinary super calender, gloss calender or soft calender without any particular effort. Especially 50 ℃ or more, more preferably 80
A more desirable result can be obtained by passing the paper through a pressure nip composed of a metal roll heated to a temperature of not less than 0 ° C. and a heated or unheated elastic roll for smoothing treatment. Further, it is appropriately used in on-machine and off-machine, and the form of the pressurizing device, the number of pressurizing nips, etc. are appropriately adjusted in accordance with a normal smoothing processing device. In addition, in order to obtain the desired excellent smoothness of the present invention, it is important to select a smoother support.

As the support, for example, plain paper, synthetic paper, synthetic resin film, paper, synthetic paper, non-woven fabric, cloth, metal foil provided with an undercoat pigment coating layer or resin layer, or a composite sheet obtained by laminating these Etc. are appropriately selected and used. The support may be selected depending on the process used and the end use, and the most suitable one may be determined from the above various supports. Even if a support other than paper is used, it is often referred to as an image receiving paper. Therefore, the image receiving paper includes such a support as described above. Of these, plain paper is preferable because it has excellent thermal characteristics in the heat-melting type thermal transfer recording system. Specific examples of plain paper include pulp fiber as a main component, paper strength enhancer, sizing agent, retention aid, inorganic or organic filler and the like to make paper, and further starch or starch derivative as required. It is obtained by sizing with a water-soluble adhesive such as, for example, general high-quality paper, various mechanical pulp (BCTMP, CTMP, SGP
, RGP, etc.) and DIP, etc.
Examples thereof include so-called neutral paper-made neutral papers and the like, which are weakly acidic to weakly alkaline to about 9. Furthermore, papers such as cast-coated paper, art paper, coated paper, and slightly coated paper, which have a pre-coated layer containing a pigment such as kaolin clay, calcium carbonate, and titanium dioxide as a main component to improve the surface properties, are also used. It is possible. As the paper machine, a Fourdrinier paper machine, a twin wire paper machine, a round wire paper machine, a Yankee paper machine, or the like can be appropriately used.

[0041]

The present invention will be described in more detail below with reference to examples, but of course the present invention is not limited to these ranges. In addition, "parts" and "%" in the examples mean "parts by weight" and "% by weight" unless otherwise specified.

[Surface Activation Treatment of Calcium Carbonate] 100 parts of powdery light calcium carbonate A is added to 100 parts of a 1% aqueous solution of special acid-modified polyvinyl alcohol (trade name: Goshenal T-330H / Nippon Gosei Kagaku). It was dispersed using a Corless disperser, and an antifoaming agent was added to this to prepare a dispersion liquid. This dispersion was passed through a horizontal sand mill filled with spherical glass beads (bead diameter: 2 mm, filling rate: 60%) at a flow rate that resulted in an average residence time of 1 minute to perform surface activation treatment, and calcium carbonate E Got Similarly, powdery light calcium carbonates B, C, and D were subjected to surface activation treatment to obtain calcium carbonates F, G, and H, respectively, as shown in Table 1.

The physical properties such as the average particle diameter and the shape of the particles of calcium carbonate were measured or observed by the following methods, and the results are shown in Table 1.

(Measurement of Primary Particle Diameter D) Based on the specific surface area S measured by the BET specific surface area measuring method, the primary particle diameter was calculated by the following formula. D = 6 / (S · ρ) D; primary particle diameter (μm) of calcium carbonate calculated from the value of the specific surface area measured by the BET specific surface area measuring method.
S: Specific surface area (m ² / g) of calcium carbonate measured by the BET specific surface area measuring method. ρ: True specific gravity of calcium carbonate (g / cm ³ ).

(Measurement of secondary particle diameter d) The total amount is 300 in advance.
g, water was added so that the final concentration would be 25% 500
Set the desktop propeller mixer in a ml container and
The required calcium carbonate was added with stirring at rpm. After the addition, the slurry of calcium carbonate obtained by stirring for 10 minutes was used as an X-ray transmission type particle size distribution analyzer (Sedigraph
5000-01 type / Shimadzu Corp.) is used and the cumulative weight is 50
%, The particle size was measured, and the obtained value was determined as the secondary particle size d.

(Observation of Particle Shape) The particle shape was observed with a secondary electron beam using a scanning electron microscope.

Example 1 [Preparation of support] A pulp slurry prepared by mixing 10 parts of NBKP (material / spruce; freeness (CSF) = 480 ml) and 90 parts of LBKP (material / maple; CSF = 480 ml),
As a filler, 15 parts of talc, 1.5 parts of rosin emulsion sizing agent and 2 parts of sulfuric acid band were added, and the mixture was diluted with white water to prepare a paper stock having a pH of 5.3 and a solid content concentration of 1.1% by weight. This stock was made using a Fourdrinier paper machine and then coated with a size press machine so that the dry weight of the oxidized starch would be 1.5 g / m ² and dried to obtain a weight of 84 g / m ² . A support was obtained.

[Preparation of coating liquid] As shown in Table 2, the apparent specific gravity was 85 parts (solid content; the same applies hereinafter) of calcium carbonate E.
To 15 parts of 0.15 g / cm ³ of amorphous silica, 0.4 parts of sodium polyacrylate (solid content ratio to the pigment; the same applies below) was added and dispersed in water using a Choles disperser to prepare a pigment slurry. Add polyvinyl alcohol 13 to this pigment slurry.
Parts, styrene / butadiene copolymer latex 2 parts, sodium chloride 2.5 parts and optical brightener 1 part were added and stirred, and water was added to prepare a coating liquid having a solid content concentration of 50% by weight.

[Formation of Image-Receiving Layer] This coating liquid is applied onto one surface of the above-mentioned support using a blade coater so that the coating weight is 10 g / m ^{2 in} dry weight, and after drying, temperature
The image was passed through a pressure nip (nip number 11, nip linear pressure 200 Kg / cm) composed of a metal roll and an elastic roll at 60 ° C. to obtain a thermal transfer recording image receiving paper having a basis weight of 94 g / m ² .

Examples 2 to 3 Similar to Example 1 except that the coating liquid was prepared by changing the kind of calcium carbonate and the number of blending parts as shown in Table 2 in the preparation of the coating liquid of Example 1. And the rice tsubo is 94 g / m ²
An image receiving paper for thermal transfer recording was obtained.

Example 4 [Preparation of support] In Example 1, mixed filler of heavy calcium carbonate and kaolin instead of talc (mixing ratio 4:
18 parts of 1) was added, 0.5 part of sulfuric acid band, 0.5 part of cationic starch and 0.5 part of alkyl ketene dimer were added, and the mixture was diluted with white water.
Add 0.02 parts of anionic polyacrylamide to pH
A stock having a solid content of 7.9 and a solid content of 1.15% by weight was prepared. This paper material was paper-made using a Fourdrinier paper machine, and then a size press liquid obtained by mixing oxidized starch and calcium carbonate E (mixing ratio 4: 1) was applied at a dry weight of 4 g / m ² It is applied with a size press machine so that it becomes 86 g.
A support of / m ² was obtained.

[Preparation of coating liquid] As shown in Table 2, the apparent specific gravity was 80 parts (solid content; the same applies hereinafter) of calcium carbonate H.
0.4 parts of sodium polyacrylate was added to 20 parts of 0.20 g / cm ³ of amorphous silica and dispersed in water using a Choles disperser to prepare a pigment slurry. To this pigment slurry, 12 parts of polyvinyl alcohol, 1 part of styrene / butadiene copolymer latex, 2 parts of oxidized starch, 2.5 parts of sodium chloride and 1 part of optical brightener were added and stirred, and water was further added to obtain a solid content concentration. A coating liquid of 50 wt% was prepared.

[Formation of Image Receiving Layer] This coating liquid was applied to one surface of the above-mentioned support by using a bar coater so that the coating amount was 8 g / m ^{2 in} dry weight. In the same manner as in 1, an image receiving paper for thermal transfer recording having a basis weight of 94 g / m ² was obtained.

Examples 5 to 7 In the same manner as in Example 4 except that the coating liquid was prepared by changing the number of parts of calcium carbonate and the kind of porous pigment as shown in Table 2, An image receiving paper for thermal transfer recording having a basis weight of 94 g / m ² was obtained.

Comparative Examples 1 to 4 In the preparation of the coating liquid of Example 1, as shown in Table 2, the type of calcium carbonate and the number of blended parts were changed, and polyvinyl alcohol was further added from 13 parts to 18 parts for coating. An image receiving paper for thermal transfer recording having a basis weight of 94 g / m ² was obtained in the same manner as in Example 1 except that the liquid was prepared.

Comparative Examples 5 to 8 Rice was prepared in the same manner as in Example 4 except that the coating liquid was prepared by changing the types of calcium carbonate and porous pigment as shown in Table 2. An image receiving paper for thermal transfer recording having a basis weight of 94 g / m ² was obtained.

The 15 types of image-receiving papers for thermal transfer recording thus obtained were subjected to measurement and quality evaluation by the following methods, and the obtained results are shown in Table 3. (Measurement of the glossiness of the blank surface of the image receiving layer) Gloss meter (GM-3
D-type / Murakami Color Research Laboratory) is used, JIS-P-8142
75% specular gloss (%) of the image receiving layer surface
Was measured.

(Measurement of Ten-Point Average Roughness of Image Receiving Layer Surface) Using a universal surface shape measuring instrument (SE-3C type / manufactured by Kosaka Laboratory Ltd.), in accordance with JIS-B-0601, standard length The ten-point average roughness (μm) of the image receiving layer surface at 8 mm was measured.

(Measurement of Recorded Image Density) A heat transfer ink type thermal transfer type color printer (CHC-443 type / manufactured by Shinko Denki Co., Ltd.) was used, and a three color ink ribbon (product number /
060-97-0101) was used to record a test pattern having solid, grid, and halftone recording, and the density of the black solid part of the obtained recorded image was measured by a Macbeth densitometer (RD-100 R type / Macbeth Corporation). Manufactured).

(Measurement of Glossiness of Recorded Image Surface) The above-mentioned indigo solid portion (single color portion), green solid portion (two-color mixed portion), and black solid portion (3) obtained by the test pattern of the recorded image surface. For each recorded image surface of the color mixing part), a gloss meter (G
M-3D type / Murakami Color Research Laboratory), and JIS-
The 60-degree specular gloss (%) was measured by the method according to Z-8741.

(Evaluation of dot reproducibility on recorded image surface) The above-mentioned halftone dot portion on the recorded image surface is analyzed by a dot analyzer (DA-30
00) and magnified 30 times, and the degree of dot dropout and sharpness (bleeding) was visually evaluated according to the following evaluation criteria. ◎:
The dots are sharp, and there is no omission, which is extremely good. ○:
There is almost no dot blurring or omission, which is good. Δ: There is bleeding or omission of dots and it is slightly inferior. X: Many dots are bleeding or missing and inferior.

(Evaluation of Image Quality of Recorded Image Surface) With respect to the above-mentioned recorded image surface, the quality of the recorded image was visually comprehensively evaluated according to the following evaluation criteria. ⊚: A very clear image with no color misregistration or uneven density, with excellent image quality. ◯: A clear image with almost no color misregistration or uneven density, and good image quality. Δ: Color misregistration and uneven shading are observed, the image is slightly dull, and the image quality is slightly inferior. X: Color misregistration and uneven density are recognized, the image is not smooth, and the image quality is poor.

(Producing Condition of Paper Powder) The paper was cut with a cutter, and the producing condition of paper powder at that time was visually evaluated according to the following evaluation criteria. ◯: Excellent because no paper dust was generated. Δ: Slightly inferior due to generation of paper dust. X: Generation of paper dust is large and inferior.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

[0067]

As is clear from the examples in Table 3, the image-receiving paper for thermal transfer recording of the present invention has a particularly high white paper glossiness and a high image glossiness on the recorded image surface, is excellent in image sharpness, and is excellent in transfer. Since the dot reproducibility is free from unevenness, bleeding of transfer dots, and omission, it was a high-quality and high-quality image-receiving image for thermal transfer recording, which was excellent not only for high-speed recording but also for full-color recording paper.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fudou Yasuda 4-3-1 Jōkoji, Amagasaki City, Hyogo Prefecture Kanzaki Paper Co., Ltd. Kanzaki Mill

Claims (5)

[Claims] 1. An image-receiving paper for thermal transfer recording having an image-receiving layer for receiving a heat-meltable ink on a support, wherein the image-receiving layer comprises a coating composition containing the following pigments and an adhesive as main components, The glossiness of the recorded image surface (JIS-
An image-receiving paper for thermal transfer recording characterized by having a 60-degree specular gloss of 45% or more according to Z-8741. Porous pigment having an apparent specific gravity (JIS-K-6220) of 0.10 to 0.50 g / cm ³ Calcium carbonate surface-activated by a dispersing machine using a medium in the presence of a hydrophilic medium containing a water-soluble protective colloid agent Pigment 2. The image-receiving paper for thermal transfer recording according to claim 1, wherein the surface-activated calcium carbonate pigment simultaneously satisfies the conditions of the following formulas [1] and [2]. 1.2 ≤ d / D ≤ 6.0 [1] 0.1 ≤ d ≤ 1.5 [2] d: Average particle size (μm) by Sedigraph X-ray transmission type particle size distribution measurement method D: BET Based on specific surface area by specific surface area measurement method Average particle size (μm) 3. 5 parts by weight of 100 parts by weight of calcium carbonate pigment
The image receiving paper for thermal transfer recording according to claim 1, which further comprises -80 parts by weight of a porous pigment. 4. The coating composition has an adhesive compounding ratio of pigment 100.
The image receiving paper for thermal transfer recording according to claim 1, which is 1 to 50 parts by weight with respect to parts by weight. 5. The image receiving paper for thermal transfer recording according to claim 4, wherein the main component of the adhesive is polyvinyl alcohol.