JP3000813B2 - Image receiving paper for thermal transfer recording and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a thermal transfer recording image-receiving paper used in a copying machine, a printer, a facsimile or the like utilizing a thermal transfer recording system.

[0002]

2. Description of the Related Art In recent years, with the progress of OA, copiers and printers using various recording systems such as an electrophotographic system and a thermal transfer recording system have been widely used. These are also used, for example, in CAD / CAM, etc., according to their respective applications. In this case, a colored coloring material is used for image formation, but these coloring materials are usually melted, evaporated, and sublimated,
The image is transferred onto a recording medium such as paper or a film sheet, and a recorded image is obtained by adhesion, adsorption and dyeing.

[0003] In this type of recording method, an ink ribbon having a heat-meltable ink layer composed of a coloring material is melted by heat generated by a thermal head, and the coloring material is transferred to recording paper to be adhered, adsorbed, and dyeed. A hot-melt type thermal transfer recording system that obtains a recorded image by a deposition action has recently attracted attention. This method is characterized in that plain paper (high quality paper) can be used as a recording medium.

[0004] In this thermal transfer recording system, full color recording, high speed recording,
Demands for sharp images, high resolution, etc. are increasing. For example, when performing single-color or multi-color printing with a color thermal transfer printer or the like, a recording material is combined with a color material such as yellow, magenta, cyan, and black, an ink ribbon having waxes or resins, and a recording paper. A transfer image is formed on paper. In this case, since the inks of the respective colors overlap each other, when plain paper is used as the recording paper, defects such as transfer unevenness and missing dots are liable to occur due to the characteristics of the image receiving layer surface.

Therefore, recently, instead of using plain paper as it is, the base paper surface is coated or impregnated with a coating composition containing a pigment and an adhesive as a main component to improve the smoothness of the image receiving layer surface. Many suggestions have been made. For example, the one in which Beck's smoothness is specified (JP-A-59-13)
3092, and 59-187892), provided with a thermal transfer image-receiving layer containing a specific pigment or binder (Japanese Patent Application Laid-Open No. 57-182487,
No. 59-182787, US Pat.No. 4,639,751, JP-A-60-11
No. 0489, No. 60-110492, No. 60-192690, No. 61-2172
No. 89, No. 61-286187, No. 63-21185, JP-A 1-2534
No. 78). The technology of receiving paper using plain paper type uncoated paper and using a specific papermaking filler is also disclosed in
-225396 and 63-19289. However, although these conventional methods have some improvement effect, transfer unevenness and color shift at overlapping portions of color inks during multicolor printing, missing transfer dots (ink), poor dot shape reproducibility, etc. However, it has not been possible to completely prevent a decrease in image clarity due to the above. According to the views of the present inventors, it is not sufficient to simply enhance the smoothness by enhancing the calendering treatment or the like, or to simply include a specific pigment or binder in the thermal transfer image receiving layer,
For obtaining an image receiving paper for thermal transfer recording which is excellent in ink transferability and dot reproducibility by overcoming the above-mentioned drawbacks, no practically usable technology has been developed yet.

In recent years, the number of occasions of printing on thermal transfer recording image receiving paper has increased, and accordingly, the smoothness, surface strength, opacity, and the like of the image receiving paper have been required. Furthermore, when cutting the image receiving paper, a work environment trouble on the user side due to the generation of paper dust is revealed, and it is urgently necessary to eliminate such trouble.

[0007]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image receiving paper for thermal transfer recording, and more particularly, to an ink transfer sheet having excellent ink transferability, reproducibility, fixability, resolution and image clarity, no transfer unevenness and missing dots, and high-speed recording. Needless to say, an object of the present invention is to provide a high-quality, high-quality image receiving sheet for thermal transfer recording, which is excellent in suitability for full-color recording paper and also has suitability for printing paper.

[0008]

According to the present invention, there is provided an image receiving paper for thermal transfer recording wherein an image receiving layer is provided by coating or impregnating an aqueous coating liquid containing a pigment and an adhesive as main components on a base paper.
An image receiving paper for thermal transfer recording, characterized by simultaneously satisfying the following conditions. JIS-K-6 in the base paper
The apparent specific gravity according to 220 is 0.10 to 0.50 g / c
m is ^3, and a single particle a plurality aggregated sea urchin-like or spherical agglomerated precipitated calcium carbonate comprising, calcined kaolin, amorphous silica, zeolite, diatomaceous earth, at least one selected from calcined diatomaceous earth 6 ~ porous pigment
Contains 20% by weight. TAPPI-UM-403 for receiving paper
Is in the range of 0.05 to 0.18 ft · lb. The ten-point average roughness of the surface of the image receiving layer of the image receiving paper according to JIS-B-0601 is 6 to 20 μm.

The base paper has an apparent specific gravity according to JIS-K-6220 of 0.10 to 0.50 g / cm ³ , and has a sea urchin or spherical shape in which a plurality of single particles are aggregated. 6-20% by weight of at least one porous pigment selected from aggregated light calcium carbonate, calcined kaolin, amorphous silica, zeolite, diatomaceous earth, and calcined diatomaceous earth
The base paper is further coated with or impregnated with an aqueous coating liquid comprising a coating composition containing a pigment and an adhesive as a main component to form an image receiving layer, and the image receiving paper is subjected to TAPPI-UM-403.
Image for thermal transfer recording so that the Z-axis intensity conforming to JIS-B is 0.05 to 0.18 ft · lb and the ten-point average roughness conforming to JIS-B-0601 of the surface of the image receiving layer of the image receiving paper is 6 to 20 μm. This is a method for producing paper.

[0010]

According to the present invention, the base paper, which is the main part of the thermal transfer recording image receiving paper, is provided with an appropriate gap and cushioning property, thereby enhancing the heat insulating effect and improving the ink receptivity. It is extremely important to specify the internal strength (Z-axis strength) of the image receiving paper in the Z-axis direction as an improvement in printability and a measure against paper dust.

That is, by adding a specific filler to the base paper and adding conditions such as specifying the Z-axis strength of the image receiving paper in a multilayered manner, the synergistic effect of each of these conditions allows the base paper to be used. The heat insulating property is remarkably improved, the ink receptivity is enhanced, and the adhesion between the surface of the image receiving paper and the ink ribbon is enhanced.

Further, by adjusting the Z-axis strength of the image receiving paper to a specific range, the paper layer and the surface strength are strengthened, thereby preventing troubles caused by paper dust and, furthermore, being suitable for printing paper. And an image receiving sheet for thermal transfer recording having excellent image quality without loss of transfer dots during high-speed recording or multicolor printing.

The first feature of the present invention is that the filler in the base paper has an apparent specific gravity according to JIS-K-6220 (hereinafter, simply referred to as apparent specific gravity) of 0.10 to 0.50 g / cm ³ , preferably. Is
0.15 to 0.40 g / cm ³ , more preferably 0.20 to 0.40 g / cm ³
A ³ porous pigments 6-20% by weight, preferably 8 to 15
It is intended to contain about weight%. Porous pigments contain a large amount of air in the particles, and such pigments (fillers) are provided between pulp fibers so that the base paper has appropriate voids and cushioning properties. It was done. In other words, the receptivity and fixing property of the transfer ink are more remarkably improved in order to keep the heat insulating property of the base paper good and to store the heat from the thermal head on the surface of the image receiving layer moderately. Is also improved, so that the quality characteristics of the image receiving paper for thermal transfer recording are dramatically improved.

Among the porous pigments, the apparent specific gravity is 0.1.
When a pigment exceeding 50 g / cm ³ is used, the properties of the porous pigment are halved, the voids in the base paper are reduced, a dense paper layer structure is formed, and the heat insulating efficiency of the base paper is rapidly reduced. , The acceptability and the fixability of the film become poor. Further, the opacity is remarkably reduced because the number of small voids required for light scattering is reduced. On the other hand, in the case of a porous pigment of less than 0.10 g / cm ³ , the heat from the thermal head is cooled on the surface of the image receiving layer because the voids in the base paper increase excessively and the heat insulating effect of the base paper becomes unnecessarily high. It is difficult to perform the transfer, and heat is accumulated to induce bleeding of the transfer ink and a bridging phenomenon, thereby deteriorating the image quality. Further, since the strength of the paper layer becomes extremely weak, image quality is deteriorated due to transfer dot defects or paper dust, and further, printability is lost, which is not preferable.

In addition, even if the above-mentioned specific porous pigment is used,
If the amount used is less than 6% by weight in the base paper, the desired effects of the present invention cannot be obtained. On the other hand, if it exceeds 20% by weight, the paper layer strength of the base paper becomes weak and paper dust is generated. It is not preferable because it adversely affects image quality and lacks suitability as printing paper.

The following are examples of porous pigments that can be used in the present invention. That is, for example, sea urchin-like or spherical aggregated light calcium carbonate obtained by aggregating a plurality of single particles, calcined kaolin, amorphous silica, zeolite, diatomaceous earth, calcined diatomaceous earth, and the like are included. Among these, a porous pigment that satisfies the specific condition of the apparent specific gravity is used. Furthermore, among these pigments, the use of agglomerated or spherical aggregated light calcium carbonate, calcined kaolin, or amorphous silica is particularly excellent in transfer ink fixability and dot shape reproducibility, and in multicolor overprinting. Since the color reproducibility is good, it is possible to obtain a thermal transfer recording image-receiving paper which is excellent in gradation without color shift.

The sea urchin-like or spherical aggregated light calcium carbonate is as follows. That is, the particle size of the calcium carbonate produced during the synthetic crystallization is 0.1 to
It refers to calcium carbonate in the form of aggregated single particles (or primary particles) of 0.3 μm and firmly aggregated to such an extent that they are not separated by a general dispersing force (referred to as aggregated particles or secondary particles). In this case, the single particle having a needle column shape is referred to as a sea urchin shape, and the single particle having a cubic shape aggregated into a spherical shape is referred to as spherical aggregated calcium carbonate. The diameter of the agglomerated particles can be controlled in the range of 0.5 to 20 μm, and among them, 1 to 10 μm has attracted attention for papermaking.

On the other hand, calcined kaolin (Calcined
kaolin or Anhydrous kaoli
There are many types of n) depending on the degree of firing, particle size, and the like. Amorphous silica is amorphous synthetic silicic acid, which is called amorphous silica because it has no fixed crystal structure in comparison with naturally occurring crystalline silica. Generally, it is classified into anhydrous silicic acid of dry method, hydrous silicic acid of wet method, and hydrous aluminum silicate, and these are sometimes collectively called white carbon. Amorphous silica is an aggregated structure of fine particles, and has a single particle diameter of 10 to 50 nm, and secondary aggregated particles have a wide range of 1 to several hundred μm.

It should be noted that other fillers such as talc, kaolin, clay, delamikaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, titanium dioxide, aluminum hydroxide, and the like may be used within a range not to impair the desired effects of the present invention. Mineral fillers such as calcium hydroxide, magnesium hydroxide, zinc oxide, magnesium sulfate, calcium silicate, magnesium aluminosilicate, magnesium silicate, calcium sulfate, silica, sericite, bentonite, smectite, polystyrene resin, urea resin, acrylic resin, Fine particles such as melamine resin and benzoguanamine resin,
One or two or more fillers such as organic synthetic fillers such as fine hollow particles and the like can be appropriately selected and used in combination, and furthermore, fillers contained in waste paper, broke, and the like can be recycled.

Next, a second feature of the present invention is that the TAPPI
The Z-axis strength according to UM-403 is 0.05 to 0.1.
8 ft · lb, more preferably 0.06 to 0.16 ft
Lb range to give the surface of the receiving paper moderate flexibility and cushioning to enhance the adhesion to the ink ribbon, and furthermore, between the paper layer and the paper layer and between the paper layer and the image receiving layer It is intended to enhance the adhesion with the aqueous coating layer to be obtained, to obtain a uniform and clear recorded image without transfer unevenness and missing dots, and to have the suitability for printing paper. .

Incidentally, some conventional thermal transfer recording image receiving papers have a Z-axis strength of 0.20 ft.lb or more, but in such thermal transfer recording image receiving paper, the surface of the image receiving layer having good smoothness is poor. Even if it is formed, since the cushioning property and flexibility are insufficient, for example, when transfer recording is performed by pressing the surface of the image receiving paper and the ink ribbon and the thermal head by pressing the platen roll, the surface of the image receiving paper and the ink ribbon And uneven transfer, dot missing and the like were generated, resulting in only an inhomogeneous image, resulting in poor image quality.

If the Z-axis strength is less than 0.05 ft.lb, it is not possible to obtain an image-receiving paper having the desired strength of the paper layer and the image-receiving layer of the present invention, and it is not possible to eliminate paper dust. Further, when the ink ribbon and the image receiving paper are separated from each other at the time of thermal transfer recording, the surface of the image receiving layer is turned up with the transfer ink, and the transfer dots (ink) are lost, which causes deterioration in image quality. On the other hand, if the Z-axis intensity exceeds 0.18 ft · lb, a clear and high-quality recorded image desired by the present invention cannot be obtained for the above-described reason.

The method of adjusting the Z-axis strength of the image receiving paper for thermal transfer recording within the range of the present invention includes the types and amounts of pulp fibers, beating conditions, the types and amounts of fillers, and the types and additions of paper strength enhancers. Amount, starch, polyvinyl alcohol, polyacrylamide, cellulose derivatives, acrylates, latex, etc., surface sizing treatment with surface sizing agent or surface paper strength enhancer, dehydration condition in paper machine, wet press condition, drying condition adjustment, etc. The method is adjusted to the scope of the present invention by appropriately selecting these methods.

The pulp fiber is not particularly limited, and is mainly made of ordinary wood pulp fiber. If necessary, non-wood pulp fiber such as kenaf, bamboo, hemp, polyester, polyolefin And synthetic pulp or synthetic fiber such as polyamide, and inorganic fiber such as glass fiber and ceramic fiber. The type and production method of the pulp fiber are not particularly limited. For example, besides chemical pulp fiber such as softwood pulp and hardwood pulp obtained by the KP, SP, AP method and the like, SCP, and various high-yield pulp (SGP) , BSGP, BCTMP, CTMP, CGP, TM
Waste paper pulp or recycled pulp such as P, RGP, and CMP) or DIP. In addition, in these,
For example, chemical pulp fibers obtained from hardwood such as maple, birch, oak, oak, beech, aspen, eucalyptus, etc. have excellent cushioning properties and heat insulation properties, and are extremely effective in improving ink receptivity. It can be particularly preferably used.

In the paper stock, besides pulp fiber and filler as the main components, various retention aids and filters conventionally used in the art are used as long as the desired effects of the present invention are not impaired. An internal additive for papermaking such as a water-based improver, a paper strength enhancer, and a sizing agent is appropriately selected and used as needed. In addition, dyes,
If necessary, an internal additive for papermaking such as a fluorescent whitening agent, a pH adjusting agent, an antifoaming agent, a pitch control agent, and a slime control agent can be appropriately added. Also, when performing the above-described surface sizing treatment, together with various surface sizing agents, a synthetic sizing agent, a fluorescent whitening agent, a water-proofing agent, an antifoaming agent, an antistatic agent,
It is also possible to use pigments, dyes and the like in combination.

The papermaking method is not particularly limited. For example, an acidic papermaking method having a papermaking pH of about 4.5, a papermaking pH containing an alkaline filler such as calcium carbonate as a main component, and a papermaking pH of about 6 to about 9 are available. The present invention can be applied to all papermaking methods such as a so-called neutral papermaking method which is made alkaline.
As the paper machine, a fourdrinier paper machine, a twin wire paper machine, a round net paper machine, or the like can be used as appropriate.

After papermaking, drying, size pressing, and drying, the surface of the base paper is preferably smoothed by a machine calendar. Examples of the machine calendar include a machine calendar stack composed of multiple stages of metal rolls, a gross calendar that presses rolls onto a drum, and a soft calendar.

The present invention is characterized in that a thermal transfer recording image receiving layer is formed by coating or impregnating an aqueous coating liquid on a base paper in order to obtain a desired high quality image receiving paper for thermal transfer recording.

The coating composition in the aqueous coating liquid contains an adhesive. The adhesive in this case is water-soluble and / or
Or refers to a water-dispersible polymer compound,
There is no particular limitation. For example, cationic starch, amphoteric starch, oxidized starch, enzyme-modified starch, thermochemically modified starch, esterified starch, starches such as etherified starch, carboxymethyl cellulose, cellulose derivatives such as hydroxyethyl cellulose, gelatin, casein, soy protein, Natural or semi-synthetic polymers such as natural rubber; polydienes such as polyvinyl alcohol, isoprene, neoprene, polybutadiene, polyalkenes such as polybutene, polyisobutylene, polypropylene, polyethylene, vinyl halide, vinyl acetate, styrene, (meth) acrylic acid , (Meth) acrylic acid ester, (meth) acrylamide, vinyl polymer and copolymers such as methyl vinyl ether, synthetic rubber latex such as styrene-butadiene-based, methyl methacrylate-butadiene-based, and polyurethane Adhesives such as synthetic resins such as synthetic resins, polyester resins, poly (meth) acrylate resins, polyamide resins, olefin / maleic anhydride resins, and melamine resins. One type or two or more types are appropriately selected and used according to the quality target of the recording image receiving paper.

Further, in order to improve the ink receptivity and obtain a thermal transfer recording image receiving paper capable of exhibiting a desired high image quality,
It is preferable to provide an image receiving layer by coating or impregnating an aqueous coating liquid containing a pigment in addition to the adhesive.

Examples of the pigment used in this case include various pigments used in general coated papers, for example, kaolin, delamikaolin, aluminum hydroxide, satin white, light calcium carbonate, heavy calcium carbonate, calcium sulfate, barium sulfate, and dioxide. Titanium, calcined kaolin, talc, zinc oxide, zinc carbonate, alumina, diatomaceous earth, magnesium oxide, magnesium carbonate, silica, white carbon,
Mineral pigments such as magnesium aluminosilicate, colloidal silica, bentonite, zeolite, and sericite; fine particles such as polystyrene resin, urea resin, melamine resin, acrylic resin, and benzoguanamine resin; and fine hollow particles and other organic pigments. One or two or more of these may be used as appropriate in accordance with the quality target of the thermal transfer recording image-receiving paper. The amount of the pigment is preferably 0 to 95% by weight, preferably 10 to 90% by weight based on the solid content, in order to obtain the desired effect of the present invention. When a pigment is contained, it is desirable to use powder having a powder whiteness of 75% or more, preferably 80% or more, since the whiteness of the recording paper can be improved.

In the aqueous coating liquid, in addition to these, various auxiliaries such as anionic, cationic, nonionic or amphoteric surfactants, pH adjusters, viscosity adjusters, softeners, gloss improvers, Dispersants, flow modifiers, antistatic agents, waxes, stabilizers, ultraviolet absorbers, antistatic agents, crosslinkers, sizing agents, fluorescent brighteners, coloring agents, defoamers, waterproofing agents, plasticizers Lubricants, preservatives, fragrances and the like can be used as needed.

The aqueous coating liquid thus prepared is coated or impregnated on one side or both sides of the base paper. The coated or impregnated amount satisfies the desired effect of the present invention. It does not need to be unnecessarily large as long as it is allowed to dry, and is generally 0.5 to 15 g / side on a dry weight basis.
m ² , preferably 1 to 12 g / m ² , more preferably 2 to
It is about 10 g / m ² . In forming the image receiving layer by coating or impregnating the aqueous coating liquid on the base paper, a single-coat layer of the aqueous coating liquid or a multilayer structure of two or more layers is used. Is not particularly limited. Also,
In the case of a multi-layer structure, the composition of the coating liquid of each layer does not need to be the same, and is appropriately adjusted according to the required quality level.

The apparatus for coating or impregnating is not particularly limited. For example, blade coater, air knife coater, roll coater, reverse roll coater, bar coater, curtain coater, die slot coater, gravure coater, champlex Apparatuses such as a coater, a brush coater, a two-roll or metering blade type size press coater, a bill blade coater, a short dwell coater, a gate roll coater, a spray, a pre-wet method, and a float method can be used as appropriate. Of course,
These devices may be on-machine or off-machine coaters.

The thus-prepared image receiving paper for thermal transfer recording is subjected to a smoothing treatment in a usual drying step, surface treatment step or the like, and is finished to a paper having a water content of 3 to 10% by weight, preferably about 4 to 8% by weight. Can be Incidentally, when smoothing the thermal transfer recording image receiving paper, when adjusted so that the ten-point average roughness of the image receiving layer surface according to JIS-B-0601 is in the range of 6 to 20 μm, preferably 8 to 18 μm. The desired effect of the present invention can be made more noticeable.

Incidentally, the ten-point average roughness of the image receiving layer surface is 20 μm.
If it exceeds m, the smoothness of the surface of the image receiving layer is inferior, and a high-quality recorded image desired by the present invention cannot be obtained. In addition, the running resistance of the image receiving paper at the time of recording is deteriorated due to an increase in frictional resistance, which causes a color shift of a recorded image in the case of color recording. On the other hand, if the smoothness is increased to less than 6 μm, a dense paper layer structure is likely to be formed, and the heat insulating property is reduced by half.
For example, the shape of the transfer dot is too thin, and as a result, the color tone of the mixed color portion recorded by overlapping the multi-color inks is visually recognized different from the original color tone, which causes the color reproducibility to deteriorate. Further, the fixing property of the transfer ink is deteriorated, and the deterioration of the image quality due to the loss or stain of the transfer dots due to physical rubbing is not preferable.

The ten-point average roughness referred to in the present invention is measured by using a universal surface shape measuring instrument SE-3C (manufactured by Kosaka Laboratory Co., Ltd.) and measuring the standard length according to the method specified in JIS-B-0601. 8mm
Was measured. In this method for measuring the surface roughness, 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. For this reason, the fineness of the paper surface, which has been difficult with measuring devices such as the Beck smoothness meter and Parker Print Surf, which are general air leak type smoothness testers, is affected by the air permeability of the paper. According to the detailed examination results of the present inventors, the ten-point average roughness is calculated from the center line average roughness obtained by cutting off the undulation of the image receiving layer surface. It has been clarified that the measured value has a much higher correlation with the desired effect of the smoothing treatment of the present invention.

When the thermal transfer recording image-receiving paper is subjected to a smoothing process, it is carried out by a normal smoothing device such as a super calender, a gross calender, a soft calender, etc. In particular, if the smoothing treatment is performed by passing paper between a metal roll heated to 50 ° C or higher, preferably 80 ° C or higher and a pressure nip constituted by a heated or non-heated elastic roll,
More desirable results are obtained. These smoothing devices are appropriately used on-machine or off-machine, and the form of the pressure device, the number of pressure nips, and the like are appropriately adjusted in accordance with a normal smoothing device.

[0039]

EXAMPLES The present invention will be described in more detail with reference to the following examples, which, of course, are not intended to limit the scope of the present invention. In the examples, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively, unless otherwise specified.

Example 1 [Preparation of base paper] A pulp slurry containing 10 parts of NBKP (material / spruce; freeness = CSF 520 ml) and 90 parts of LBKP (material / maple; freeness = CSF 480 ml) was prepared.
Spherical aggregated light calcium carbonate [apparent specific gravity =
0.31 g / cm ³ ], 0.5 part of a sulfate band, 0.7 part of a cationic starch, 0.25 part of a cationic polyacrylamide and 1.0 part of an alkenyl succinic anhydride.
These mixtures were diluted with white water to prepare a stock having a pH of 7.9 and a solid content of 0.9%. The stock is made using a twin-wire machine, then coated and dried with a size press so that the applied amount of oxidized starch is 2 g / m ² in terms of dry weight, and passed through a 3-nip machine calender. Thus, a base paper having a rice tsubo of 84 g / m ² was obtained.

[Preparation of coating liquid] To 90 parts of spindle-shaped light calcium carbonate (solid content; the same applies hereinafter) and 10 parts of titanium oxide, 0.4 parts of sodium polyacrylate (solid content ratio to pigment; the same applies hereinafter) were added. It was dispersed in water using a disperser to prepare a pigment slurry. To this pigment slurry, 20 parts of polyvinyl alcohol, 3 parts of styrene-butadiene-based synthetic rubber, and 1 part of a fluorescent brightener were added, 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 solution was coated on both sides of the above-mentioned base paper using a bar coater so that the total coating amount was 12 g / m ^{2 in} dry weight, and the temperature was reduced. The paper is passed through a pressure nip (11 nips, nip linear pressure 200Kg / cm) composed of 55 ° C metal roll and elastic roll, and the rice tsubo is 96g /
Thus, an image receiving paper for thermal transfer recording of m ² was obtained.

Example 2 A base paper and a base paper were prepared in the same manner as in Example 1 except that the stock was prepared by reducing the amount of the spherical aggregated light calcium carbonate of the filler to 8 parts. An image receiving paper was obtained.

Example 3 In the preparation of the base paper of Example 1, the type of filler was changed to add 12 parts of spherical aggregated light calcium carbonate having a different apparent specific gravity [apparent specific gravity = 0.38 g / cm ³ ]. Further, a paper stock is prepared without adding any cationic polyacrylamide, and then, in the preparation of the size press solution, an anionic polyacrylamide is used in combination with the oxidized starch, and the coating amount is calculated by dry weight.
Example 1 was repeated except that a size press solution was prepared by adding 0.15 g / m ² to prepare a base paper.

Example 4 In the preparation of the base paper of Example 3, 10 parts of spherical aggregated light calcium carbonate and calcined kaolin [apparent specific gravity = 0.
34 g / cm ³ ] The procedure of Example 1 was repeated, except that 5 parts of a filler mixture was added to prepare a stock, and a size press was performed as in Example 3 to prepare a base paper.

Example 5 [Preparation of base paper] A pulp slurry prepared by mixing 5 parts of NBKP (material / spruce; freeness = CSF 520 ml) and 95 parts of LBKP (material / eucalyptus; freeness = CSF 460 ml) was used.
Calcined kaolin (apparent specific gravity = 0.34 g / cm ³ ) was used as a filler.
Parts, rosin emulsion sizing agent (1.0 part), sulfuric acid band (1.5 parts) and cationic polyacrylamide (0.1 part), and the mixture was diluted with white water.
A stock having an H of 5.4 and a solid content of 0.96% was prepared. This paper stock is paper-made using a fourdrinier paper machine, and then coated with an oxidized starch and an anionic polyacrylamide to a dry weight of 2 g / m ² and 0.2 g / m ² respectively by a size press, and dried. The paper was passed through a nip machine calendar to obtain a base paper having a rice tsubo of 90 g / m ² .

[Preparation of Coating Liquid] A pigment slurry was prepared by adding 0.4 parts of sodium polyacrylate to 85 parts of rice granular light calcium carbonate and 15 parts of titanium oxide and dispersing in water using a Cores dispersing machine. To this pigment slurry, 20 parts of polyvinyl alcohol, 5 parts of styrene-butadiene-based synthetic rubber, 1 part of a fluorescent brightener and water were added and mixed to prepare a coating liquid having a solid content concentration of 40% by weight.

[Formation of Image-Receiving Layer] The obtained coating liquid was coated on one side of the base paper using an air knife coater so that the coating amount was 6 g / m ^{2 in} dry weight. In addition, the temperature of the metal roll and the linear pressure of the
And the paper was changed to 150 Kg / cm.
^Thus, an image receiving paper for thermal transfer recording was obtained.

Example 6 In the preparation of the base paper of Example 5, the filler had an apparent specific gravity of 0.43.
The procedure was the same as in Example 5 except that the stock was prepared by changing to 15 parts of calcined kaolin of g / cm ³ .

Examples 7-8 In the preparation of the base paper of Example 5, the filler had an apparent specific gravity of 0.20.
g / cm ² of amorphous silica 12 parts added (Example 7), and apparent specific gravity were prepared stock change respectively in 10 parts addition of amorphous silica of 0.13 g / cm ² (Example 8) Except for the above, a base paper and an image receiving paper were obtained in the same manner as in Example 5.

Example 9 In the preparation of the base paper of Example 5, the calcined kaolin was reduced to 8 parts and the amount of cationic polyacrylamide was reduced to 0.
Example 5 was repeated except that the stock was increased to 25 parts.

Comparative Example 1 The preparation of the base paper of Example 1 was repeated except that the paper stock was prepared by changing the addition of 20 parts of spherical aggregated light calcium carbonate and the addition of 0.1 part of cationic polyacrylamide. In the same manner as in Example 1, a base paper and an image receiving paper were obtained.

Comparative Example 2 Except that the stock was prepared by reducing the amount of spherical aggregated light calcium carbonate to 5 parts in the preparation of the base paper of Comparative Example 1,
It was the same as Comparative Example 1.

COMPARATIVE EXAMPLE 3 In the preparation of the base paper of Example 1, except that the type of filler was changed and 20 parts of light calcium carbonate (apparent specific gravity = 0.56 g / cm ³ ) was added to prepare the paper stock. It was the same as in Example 1.

Comparative Examples 4 to 5 In the preparation of the base paper of Example 5, the addition of 22 parts of calcined kaolin (Comparative Example 4) and the addition of 8 parts (Comparative Example 5) were carried out. A base paper and an image receiving paper were obtained in the same manner as in Example 5, except that the stock was prepared by increasing the amount of the cationic polyacrylamide to 0.4 part.

Comparative Example 6 In the preparation of the base paper of Example 5, except that the type of filler was changed and 8 parts of talc having an apparent specific gravity of 0.75 g / cm ³ was added to prepare the stock. Same as 5.

Comparative Examples 7 to 8 In the preparation of the base paper of Example 8, the type of amorphous silica was changed, and 20 parts of amorphous silica having an apparent specific gravity of 0.55 g / cm ³ was added (Comparative Example 7). A base paper and an image receiving paper were obtained in the same manner as in Example 8, except that a stock was prepared by adding 10 parts of amorphous silica having an apparent specific gravity of 0.07 g / cm ³ (Comparative Example 8).

The 17 types of thermal transfer recording papers thus obtained were measured and evaluated for quality by the following methods. The results are shown in Table 1.

(Measurement of Z-axis strength) Using an internal bond tester (manufactured by Edwin H. Benz), the Z-axis strength (ft · lb) was measured in accordance with TAPPI UM-403.

(Measurement of Ten-Point Average Roughness of Paper Image-Receiving Layer Surface)
Using a universal surface profiler SE-3C (manufactured by Kosaka Laboratories), the ten-point average roughness (μm) of the image receiving layer surface at a reference length of 8 mm was measured in accordance with JIS-B-0601.

(Measurement of Image Density) Using a thermal transfer type color printer (CHC-443 type, manufactured by Shinko Electric Co., Ltd.), a test pattern having a rainbow, a grid, and a halftone dot was recorded. The density of the solid black portion was measured with a Macbeth densitometer (RD-100 R type, manufactured by Macbeth).

(Evaluation of Image Quality of Recording Surface) The above recording surface was visually evaluated comprehensively for the quality of the recorded image according to the following evaluation criteria. A: Very clear image with no color shift and non-uniform density, and excellent image quality. ：: A clear image with almost no color shift and non-uniform density, and good image quality. Δ: Color misregistration and shading were recognized, and the image was dull.
Poor image quality.

(Evaluation of dot reproducibility on recording surface) The halftone dots on the recording surface were measured by a dot analyzer (DA-3000).
The degree of dot omission and sharpness (bleeding) was visually evaluated according to the following evaluation criteria. ：: The dots are sharp and have no omission and are extremely excellent. ：: good with little bleeding or missing dots. Δ: Slightly inferior with bleeding or missing dots. ×: Many dots are blurred and missing.

(Evaluation of Printing Strength) Printing was performed using an RI printing suitability tester (manufactured by Mei Seisakusho Co., Ltd.) and visually evaluated according to the following evaluation criteria. A: Excellent without picking. ：: Good with almost no picking. Δ: Picking occurred and slightly inferior. X: Many occurrences of picks were inferior.

[0065]

[Table 1]

[0066]

As is clear from the examples in Table 1, the thermal transfer recording image-receiving paper of the present invention has particularly high image density, excellent image clarity, uneven transfer and bleeding of transferred dots.
Since there is no dropout and excellent dot reproducibility, it is a high-quality and high-quality image receiving paper for thermal transfer recording, which is excellent not only in high-speed recording but also in full-color recording paper and has excellent printability.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-162993 (JP, A) JP-A-4-14490 (JP, A) JP-A-61-237689 (JP, A) 124896 (JP, A) JP-A-64-45687 (JP, A) JP-A-62-288085 (JP, A) JP-A-4-91991 (JP, A) JP-A-4-366690 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (2)

(57) [Claims] 1. An image receiving sheet for thermal transfer recording, wherein an image receiving layer is provided by coating or impregnating an aqueous coating liquid containing a pigment and an adhesive as main components on a base paper, and the following conditions are simultaneously satisfied. An image receiving paper for thermal transfer recording, characterized in that: The apparent specific gravity according to JIS-K-6220 is 0.1 in the base paper.
0 to 0.50 g / cm ³ and selected from sea urchin-like or spherical aggregated light calcium carbonate formed by aggregating a plurality of single particles, calcined kaolin, amorphous silica, zeolite, diatomaceous earth, and calcined diatomaceous earth 6 to 20% by weight of at least one porous pigment obtained. TAPP on receiving paper
The Z-axis strength based on I-UM-403 is 0.05 to 0.
18 ft · lb. JIS of image receiving layer surface of image receiving paper
10 point average roughness according to -B-0601 is 6 to 20 µm
It is. 2. A sea urchin or spherical shape in which a base paper has an apparent specific gravity according to JIS-K-6220 of 0.10 to 0.50 g / cm ³ and a plurality of single particles are aggregated. Aggregated light calcium carbonate, calcined kaolin, amorphous silica,
Zeolite, diatomaceous earth, at least one porous pigment selected from calcined diatomaceous earth is contained in an amount of 6 to 20% by weight,
Further, on the base paper, an image-receiving layer is provided by coating or impregnating an aqueous coating liquid comprising a coating composition containing a pigment and an adhesive as main components, and the image-receiving paper is provided with a Z-axis conforming to TAPPI-UM-403. A method of manufacturing an image receiving paper for thermal transfer recording so that the strength is 0.05 to 0.18 ft · lb and the ten-point average roughness of the image receiving layer surface of the image receiving paper according to JIS-B-0601 is 6 to 20 μm. .