JP4225191B2 - Thermal transfer receiving sheet - Google Patents

Description

  The present invention relates to a thermal transfer receiving sheet (hereinafter simply referred to as a receiving sheet) used in a printer for transferring an image of a thermal transfer dye sheet to an image receiving layer by heat to form an image. More specifically, the present invention relates to a receiving sheet that is suitable for thermal printers, particularly dye thermal transfer printers, and can obtain images with high density and excellent uniformity similar to silver salt photographs.

  In recent years, among thermal printers, dye thermal transfer printers capable of printing clear full-color images have attracted attention. The dye thermal transfer printer includes a dye layer containing a dye of a thermal transfer dye sheet (hereinafter simply referred to as an ink ribbon), and an image receiving layer (hereinafter simply referred to as a receiving layer) containing a dye dyeable resin of the receiving sheet. And a dye at a predetermined position of the dye layer is transferred onto the receiving layer by a predetermined concentration by heat supplied from a thermal head or the like to form an image. The ink ribbon generally has a dye layer of three colors of yellow, magenta and cyan, or four colors obtained by adding black to this. A full-color image is obtained by repeatedly transferring each color dye on the ink ribbon to the receiving sheet in order.

  The image quality of recorded images in thermal transfer printers has been greatly improved by the development of digital image processing technology using computers, and the market for thermal transfer systems is expanding. In addition, as the demand for higher speed and higher sensitivity of the printing system increases, it becomes an important technical issue how to efficiently use the heat generated by the heating device for image formation as the thermal head temperature control technology improves. ing. With the increase in printing speed, improvement of color misregistration and the like has become a new technical issue in order to obtain a clear image quality. For example, in a printer, a receiving sheet is sandwiched between a metal roll and a rubber roll on which spikes are mounted, and a method of increasing the nip pressure between rolls or increasing the spikes has been attempted. However, in such a method, a dent is produced in the stamp screen of the receiving sheet, and the commercial value is lowered. Accordingly, it is required that the receiving sheet is not depressed even when the compressive force is applied by the transport roll.

  The receiving sheet is generally composed of a support and a receiving layer formed on the surface thereof. When a normal film is used as the support substrate, the film is excellent in smoothness, but the heat from the thermal head moves into the substrate, resulting in insufficient recording sensitivity, and the film does not have sufficient cushioning properties. Therefore, the adhesion between the ink ribbon and the receiving sheet is insufficient, resulting in density unevenness. In order to solve such problems, as a support, a support in which a foam film is bonded to a core material layer such as paper (for example, see Patent Document 1), and a thermoplastic resin such as a polyolefin resin as a main component. And a support or the like in which a biaxially stretched film (synthetic paper) including a void (void) structure is bonded to a core material layer such as paper has been proposed (for example, see Patent Document 2). Receptor sheets using these supports are excellent in heat insulation and smoothness, but have drawbacks such as no paper texture and high cost.

When paper is used as the support base material of the receiving sheet, the recording sensitivity is insufficient as in the case of the film and the cushioning property is slightly better than the film, but the ink ribbon and the receiving layer are unevenly adhered due to uneven density of paper fibers. Due to this, there is a tendency that unevenness of the printed image occurs. Therefore, a receiving sheet is disclosed in which an intermediate layer containing hollow particles is provided between the paper support and the receiving layer in order to improve the transfer density (see, for example, Patent Documents 3 to 6). The sensitivity of these receiving sheets is improved by the heat insulating property of the intermediate layer containing the hollow particles and the cushioning effect.
However, when such a receiving sheet is used in a current high-speed printer, the intermediate layer containing hollow particles is crushed by the pressure during conveyance in the printer or at the time of printing, and it is difficult to obtain sufficient image quality. There has been a problem such as a dent in the receiving sheet that impairs the appearance.

  Further, in order to improve the smoothness of the surface of the receiving sheet, a receiving sheet provided with a porous layer composed of a plurality of layers and a laminate layer formed by a thermoplastic resin extrusion method on the porous layer has been proposed. (For example, refer to Patent Document 7). However, the porous layer on the core layer side uses a bubble-containing resin liquid by stirring and a thermally expandable resin that forms an excessive hollow, and it is difficult to obtain sufficient smoothness. During the formation, the porous structure of the porous layer may be deformed and crushed by heat, and the sensitivity and image quality improvement effects are not always satisfactory. In addition, a receiving sheet in which two or more kinds of fine hollow particles having different particle diameters are contained in the receiving layer has been proposed (see, for example, Patent Document 8). There is a tendency that the heat insulating property and the cushioning effect cannot be sufficiently obtained, the dyeing property of the receiving layer is adversely affected, and the uniformity of the image is insufficient.

JP 61-197282 A (first page) JP-A-62-198497 (first page) JP-A-63-87286 (pages 1 and 2) JP-A-1-27996 (pages 1 to 3) JP-A-9-99651 (2nd page) JP 2001-39043 A (second page) JP 2000-272259 A (2nd page) JP 11-291647 A (second page)

  The present invention has been made in view of the circumstances as described above, solves the above-described problems of conventional receiving sheets, is particularly suitable for dye thermal transfer printers, has sufficient strength against compression of the receiving sheet, An object of the present invention is to provide a low-cost thermal transfer receiving sheet that does not cause dents in the receiving sheet, provides a high print density and a good uniform image.

The present invention includes the following inventions.
(1) In a thermal transfer receiving sheet in which an intermediate layer containing hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support, the intermediate layer includes two kinds of hollow particles A having different average particle diameters and contains the hollow particles B, a mean average particle size L _a of each of the hollow particles ([mu] m) particle size L _B ([mu] m) is less than the following relational expression (1) to (3) simultaneously, said intermediate layer A thermal transfer receiving sheet , further comprising a barrier layer mainly composed of a water-soluble resin and / or a water-dispersible resin between the image receiving layer and the image receiving layer .
L _A = 2 to 35 μm (1)
L _B = 0.2 to 9 μm (2)
0.05 ≦ L _B / L _A ≦ 0.4 (3)
(2) The thermal transfer receiving sheet according to item (1), wherein the coefficient of variation of each of the average particle diameter L _A and the average particle diameter L _B is 35% or less.
(3) The thermal transfer receiving sheet according to (1) or (2), wherein the hollow particle A has a volumetric hollowness of 60 to 97%, and the hollow particle B has a volumetric hollowness of 30 to 97%.
(4) before Symbol barrier layer contains further swelling inorganic layered compound is a particle average major axis is 0.1~100μm the swellable inorganic layered compound, and particles having an average aspect ratio (layer compound length / The thermal transfer receiving sheet according to any one of (1) to (3), wherein the thickness ratio is 5 to 5,000.

  The receiving sheet of the present invention is particularly suitable for a dye thermal transfer printer, has sufficient strength against compression of the receiving sheet, does not cause dents in the receiving sheet, provides a high print density and a good uniform image, and is low in cost. This is a thermal transfer receiving sheet.

  The receiving sheet of the present invention has a configuration in which an intermediate layer containing two types of hollow particles A and hollow particles B having different average particle diameters and a receiving layer are sequentially formed on a sheet-like support. It is of course possible to provide another layer as the intermediate layer to form a multilayer structure of two or more layers. Hereinafter, these configurations will be described in detail.

(Sheet support)
As the sheet-like support used for the receiving sheet of the present invention, paper or synthetic resin film mainly composed of cellulose pulp is used. For example, paper such as high-quality paper (acidic paper, neutral paper, etc.), medium-quality paper, coated paper, art paper, glassine paper, resin-laminated paper, or polyolefin such as polyethylene or polypropylene, polyester such as polyethylene terephthalate, A stretched film mainly composed of polyamide, polyvinyl chloride, polystyrene, or the like, or a polyolefin or polyester resin as a main component, and a melt mixture in which an incompatible resin or inorganic pigment is blended with these resins are extruded from an extruder. Further, a porous stretched film (for example, synthetic paper, porous polyester film) having a single layer structure or a multilayer structure in which voids are generated by stretching, and these films, or these films and other films or papers, etc. A composite film or the like in which and are laminated and used is appropriately used. Although there is no particular limitation, in the case of a sheet-like support mainly composed of cellulose pulp, it has a good texture as a receiving paper, is advantageous in terms of cost, and more excellent effects of the present invention can be obtained.

  The sheet-like support of the present invention may have a structure in which a first base material layer on which a receiving layer is formed, an adhesive layer, a release agent layer, and a second base material layer may be sequentially laminated. Of course, supports having a type of structure can also be used.

  The sheet-like support used in the present invention preferably has a thickness of 50 to 250 μm. Incidentally, if the thickness of the support is less than 50 μm, the mechanical strength is insufficient, the rigidity of the resulting receiving sheet is small, the repulsive force against deformation is insufficient, and the curling of the receiving sheet that occurs during printing is sufficiently prevented. There are things that cannot be done. If the thickness exceeds 250 μm, the thickness of the obtained receiving sheet becomes excessive, so that the capacity of the printer increases when the number of receiving sheets stored in the printer is reduced or when a predetermined number of sheets is stored. May cause problems such as making it difficult to make the printer compact.

(Middle layer)
In the present invention, an intermediate layer is formed directly on at least one surface of the sheet-like support or, if necessary, via an undercoat layer. The intermediate layer is composed of a plurality of kinds of hollow particles having a specific average particle size and distribution as a main component and an adhesive resin, and since this intermediate layer has a porous structure, the heat insulating property of the receiving sheet is improved. The print density is increased and the image quality is improved.
By forming the intermediate layer, the receiving sheet is given a suitable degree of deformation freedom, and the shape followability and adhesion of the receiving sheet to the shape of the printer head and ink ribbon are improved, thereby improving the thermal efficiency of the printer head with respect to the receiving layer. Even when low energy is applied, the print density can be increased and the image quality can be improved. In addition, in a high energy application region of a high-speed printer, it is possible to simultaneously prevent printing defects due to ribbon wrinkles generated on the ink ribbon.

The intermediate layer of the present invention is reinforced by filling hollow particles having a constant small particle size between hollow particles having a constant large particle size, thereby enhancing the compression resistance of the intermediate layer and The entire sheet is difficult to collapse. This structure also reduces the irregularities on the surface of the intermediate layer and improves the surface uniformity, thereby improving the image quality of the print.
Therefore, even if the receiving sheet is subjected to high pressure by the thermal head of the printer and the transport roll, the stress is absorbed inside the receiving sheet due to the improvement in compression resistance, and is restored immediately after the stress is removed. Generation of spike marks, dents, etc. on the sheet mark screen is prevented.

The average particle diameter L _A of the hollow particles A contained in the intermediate layer of the present invention is 2 to 35 μm, preferably 3 to 30 μm, more preferably 3 to 25 μm. The average particle size of less than L _A is 2 [mu] m, small particle size of the hollow particles A, the volume of the hollow portion is insufficient, heat insulation and cushioning property is insufficient, hardly sufficient sensitivity and image quality improving effect can be obtained. On the other hand, when the average particle diameter L _A is more than 35 [mu] m, the strength of the intermediate layer decreases, easily dent is generated in the receiving sheet during printing by the thermal head. Further, the unevenness on the surface of the intermediate layer also increases, and the uniformity and image quality of the image tend to be inferior.

The average particle diameter _{L B} of the hollow particles B is 0.2～9Myuemu, preferably 0.3～8Myuemu, more preferably 0.4～7Myuemu. When the average particle diameter L _B is less than 0.2μm, it is difficult to fill the gaps of the hollow particles A mean particle size of the hollow particles B is too small, and when the average particle diameter L _B exceeds 9μm is Further, it becomes difficult to enter the gaps between the hollow particles A, and in any case, the effect of improving the compression resistance may not be sufficiently obtained.

The average particle diameter ratio (L _B / L _A ) of the hollow particles A and the hollow particles B contained in the intermediate layer of the present invention is 0.05 ≦ L _B / L _A ≦ 0.4, preferably 0.1 ≦ L _B / L _A ≦ 0.4, and more preferably 0.15 ≦ L _B / L _A ≦ 0.3. When L _B / L _A > 0.4, the average particle diameter of the hollow particles B is excessive, so that the hollow particles B cannot enter the gaps of the hollow particles A, and when they enter, the gaps are widened. For this reason, the compression resistance of the receiving sheet tends to be insufficient. In addition, the smoothness of the surface of the intermediate layer also decreases, and as a result, the image quality and sensitivity of the resulting receiving sheet may decrease. On the other hand, when L _B / L _A <0.05, the average particle diameter of the hollow particles B is too small, so that the gaps between the particles cannot be filled, and the effect of improving the compression resistance of the receiving sheet is sufficiently obtained. Absent.

Furthermore, the variation coefficient of the particle diameter of each of the hollow particles A and the hollow particles B is preferably 35% or less, more preferably 30% or less, and further preferably 25% or less. Here, the variation coefficient of the particle diameter is a percentage of a value obtained by dividing the standard deviation of the particle diameter by the average particle diameter.
In addition, the average particle diameter of the hollow particles A and B and the standard deviation of the particle diameter can be measured using a general particle size measuring device, for example, a laser diffraction type particle size distribution measuring device (trade name: SALD2000, Shimadzu). Etc.).

When the variation coefficient of the particle diameter of the hollow particles A exceeds 35%, the hollowness decreases due to the increase in the hollow particles A in the lower limit region, the heat insulation and cushioning properties become insufficient, and sufficient sensitivity and The image quality may not be obtained, and the increase in the hollow particles A whose particle diameter is the upper limit region makes the intermediate layer insufficient in strength, so that the receiving sheet is easily dented at the time of printing. It may increase and image uniformity and image quality may be inferior.
Further, when the variation coefficient of the particle diameter of the hollow particles B exceeds 35%, it is difficult to sufficiently fill the gaps of the hollow particles A with the hollow particles B having a particle diameter of the lower limit region, and the hollow particles having a particle size of the upper limit region. In the case of the particles B, the compression resistance of the receiving sheet may be insufficient because the particles cannot enter the gaps of the hollow particles A.

The hollow particle A contained in the intermediate layer is composed of a shell formed of a thermoplastic polymer material and one or more hollow portions surrounded by the shell, and is used for forming the intermediate layer. Are hollow particles (or expandable particles) such as the following (a) and (b).
(A) Expanded hollow particles (pre-expanded hollow particles) produced by previously heating and foaming unexpanded particles made of a thermoplastic polymer material containing a thermally expandable substance.
(B) Unexpanded particles (expandable particles) made of a thermoplastic polymer material containing a thermally expandable substance. In this case, after the foamable particles are coated on the sheet-like support, the hollow particle layer is formed by heating and foaming by heat in the drying process or by heating and foaming in contact with a hot plate in the subsequent process. Is formed.

  However, as described above (b), in the method of foaming unexpanded foamable particles by heating during the manufacturing process of the receiving sheet, it is difficult to foam to a uniform particle diameter, and the particle diameter after thermal expansion is reduced. Since it cannot be strictly controlled, the surface of the intermediate layer has large unevenness and may have poor smoothness, and it may be difficult to obtain a structure in which small-sized hollow particles fill the gaps between large-sized hollow particles. . Therefore, in the present invention, the foamed hollow particles as described in (a) above are more preferably used.

  The foamed hollow particles as described in the above (a) include, for example, a volatile low-boiling hydrocarbon such as n-butane, i-butane, pentane, and / or neopentane in the thermoplastic material as a thermally expandable core substance. Encapsulated as a thermoplastic material, homopolymers or copolymers of vinylidene chloride, vinyl chloride, acrylonitrile, methacrylonitrile, styrene, (meth) acrylic acid, (meth) acrylic acid ester, etc. as capsule shell (wall) By subjecting the particles obtained as a material to a treatment such as heating in advance, the particles are thermally expanded to a predetermined particle size to obtain hollow particles in an already foamed state.

  The foamed hollow particles as described above generally have a small specific gravity, so that inorganic powders such as calcium carbonate, talc, and titanium dioxide can be thermally fused to further improve the handling workability and dispersibility. Foamed composite hollow particles that are attached to the surface of the foamed hollow particles and whose surface is coated with an inorganic powder can also be used in the present invention.

  The volume hollow ratio of the hollow particles A is preferably 60 to 97%, more preferably 65 to 95%. If the volumetric hollow ratio is less than 60%, a balance between the compression resistance of the intermediate layer, sensitivity and image quality improvement may not be obtained. On the other hand, if the volume hollowness exceeds 97%, the stability of the coating may be inferior, and the coating strength of the resulting intermediate layer may be insufficient.

The hollow particle B contained in the intermediate layer is composed of a shell formed from a thermoplastic polymer material and one or more hollow portions surrounded by the shell, and is used for forming the intermediate layer. The hollow particles as shown in (a) and (c) below are used.
(A) Expanded hollow particles (pre-expanded hollow particles) produced by previously heating and foaming unexpanded particles made of a thermoplastic polymer material containing a thermally expandable substance.
(C) The pore-forming material is volatilized and escaped from the microcapsules produced by the microcapsule polymerization method using the polymer-forming material as the shell-forming material and the volatile liquid as the pore-forming material. Microcapsule-like hollow particles obtained.

  The microcapsule-like hollow particles of the type (c) contained in the intermediate layer have a core part made of a polymer material, for example, a hard resin such as a styrene-acrylic copolymer or a melamine resin. A microcapsule containing volatile liquid, for example, water, is dried, and water is volatilized and escaped to form a hollow core portion. This microcapsule is obtained from a polymer-forming material (shell-forming material) and a volatile liquid (pore-forming material) by a microcapsule-forming polymerization method. Further, the foamed hollow particles of the type (A) are produced by the method described in the hollow particles A described above.

  The volumetric hollow ratio of the hollow particles B is preferably 30 to 97%, more preferably 35 to 95%. If the volumetric hollow ratio of the hollow particles is less than 30%, the sensitivity and image quality may be lowered. If the volume hollowness exceeds 97%, the stability of the paint may be lowered.

  The volumetric hollow ratio of the hollow particles A and B indicates the ratio of the volume of the hollow part to the volume of the particles. Specifically, the specific gravity of the hollow particle dispersion composed of the hollow particles and the poor solvent, It can be determined from the mass fraction of the hollow particles, the true specific gravity of the polymer resin forming the shell (wall) of the hollow particles, and the specific gravity of the poor solvent. The poor solvent is a solvent that does not dissolve and / or swell the resin that forms the walls of the hollow particles, and examples thereof include water and isopropyl alcohol. Further, the volumetric hollow ratio of the hollow particles can be determined from a cross-sectional photograph of the intermediate layer using, for example, a small angle X-ray scattering measurement device (trade name: RU-200, manufactured by Rigaku Corporation).

  The thickness for the intermediate layer to exhibit desired performances such as heat insulation, cushioning properties and strength improvement is preferably 20 to 110 μm, more preferably 25 to 100 μm. If the thickness of the intermediate layer is less than 20 μm, the heat insulating properties and cushioning properties are insufficient, and the sensitivity and the image quality improvement effect are insufficient. On the other hand, if the thickness exceeds 110 μm, the effects of heat insulation and cushioning are saturated, and not only higher performance cannot be obtained, but also compression resistance tends to decrease.

  The total amount of hollow particles in the intermediate layer is preferably in the range of 30 to 75%, more preferably in the range of 35 to 70% in terms of the mass ratio of the hollow particles to the total solid mass of the intermediate layer. If the mass ratio of the whole hollow particles to the total solid mass of the intermediate layer is less than 30%, the heat insulating property and cushioning property of the intermediate layer may be insufficient, and the sensitivity and image quality improvement effect may not be sufficiently obtained. On the other hand, if the mass ratio of the hollow particles exceeds 75%, the coating property of the resulting intermediate layer coating material may deteriorate, and the compression resistance of the receiving sheet may decrease.

The mixing ratio of the two types of hollow particles A and hollow particles B with different average particle sizes contained in the intermediate layer varies depending on the degree of density of the hollow particle filling, the apparent density of the hollow particles, the average particle size, and the like. When the mass of each of the hollow particles A and B contained in the intermediate layer is W _A and W _B , the mass ratio (W _B / W _A ) is preferably in the range of 0.001 to 1, more preferably 0.8. The range is from 003 to 0.8.
Further, when the hollow particles A, the average number of particles B each _N A, and _{N B,} the ratio of the number average particle _(N B / N _A) is of _{0.2 ≦ (N B / N A} ) ≦ 3 range Is more preferable, and the range of 0.25 ≦ (N _B / N _A ) ≦ 2 is more preferable. For the hollow particles A and the hollow particles B, the average particle number ratio is expressed by the following equation, where L _A and L _B are the average particle diameters and d _A and d _B are the apparent densities.
(N _B / N _A ) = (W _B / W _A ) × (L _A / L _B ) ³ × (d _A / d _B )

  The intermediate layer of the present invention contains hollow particles and an adhesive resin. As the intermediate layer coating solution of the present invention, an aqueous coating solution is preferred because the hollow particles generally have low solvent resistance. The adhesive resin used is not particularly limited. For example, hydrophilic polymer resins such as polyvinyl alcohol resins, cellulose resins and derivatives thereof, casein, starch derivatives and the like have film-forming properties, heat resistance, and flexibility. It is preferably used from the viewpoint. In addition, emulsions of various resins such as (meth) acrylic acid ester resins, styrene-butadiene copolymer resins, urethane resins, polyester resins, ethylene-vinyl acetate copolymer resins, and the like are preferable. Used as an aqueous resin. From the viewpoint of the coating strength of the intermediate layer, the adhesiveness, the coating property of the coating liquid, and the like, it is also possible to use an emulsion of the above hydrophilic polymer resin and various resins as the adhesive resin.

  The intermediate layer may be one or two of various additives such as antistatic agents, inorganic pigments, organic pigments, resin crosslinking agents, antifoaming agents, dispersing agents, colored dyes, mold release agents, lubricants, etc., as required. You may select and use a seed | species or more suitably.

  In the present invention, calendering may be performed in any step after the formation of the intermediate layer, barrier layer, receiving layer, etc., and the unevenness of the receiving sheet surface can be further reduced and smoothed. The calendar device used for the calendar process, the nip pressure, the number of nips, the surface temperature of the metal roll, etc. are not particularly limited, but as the calendar device, for example, a super calendar, a soft calendar, a gloss calendar, a clearance calendar, etc. The apparatus generally used in the paper industry can be used as appropriate. The pressure condition for calendering is preferably 0.5 to 150 MPa, more preferably 1 to 100 MPa. Moreover, as temperature conditions, the range from the room temperature to the Tg temperature of the adhesive resin for intermediate layers and the destruction of the hollow particles is preferable, preferably 20 to 150 ° C, and more preferably 30 to 120 ° C.

(Barrier layer)
In the present invention, a barrier layer is preferably provided between the intermediate layer and the receiving layer. Generally, organic solvents such as toluene and methyl ethyl ketone are used as the solvent for the coating solution for the receiving layer, so that the barrier layer prevents deformation and destruction due to swelling and dissolution of the hollow particles in the intermediate layer due to penetration of the organic solvent. It is effective as a barrier.

  As the resin used for the barrier layer, a resin having excellent film forming ability, preventing permeation of an organic solvent, and having elasticity and flexibility is used. Specifically, starch, modified starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, diester Isobutylene-maleic anhydride copolymer salt, styrene-maleic anhydride copolymer salt, styrene-acrylic acid copolymer salt, ethylene-acrylic acid copolymer salt, urea resin, urethane resin, melamine resin, amide resin, etc. The water-soluble polymer resin is used as an aqueous solution. Also, water-dispersible resins such as styrene-butadiene copolymer latex, acrylic ester resin latex, methacrylic ester copolymer latex, ethylene-vinyl acetate copolymer latex, polyester polyurethane ionomer, polyether polyurethane ionomer, etc. Can also be used. Among the above resins, water-soluble polymer resins are preferably used. Moreover, said resin may be used individually or may use 2 or more types together.

  Furthermore, the barrier layer may contain various pigments, preferably a swellable inorganic layered compound is used, which is excellent not only in preventing penetration of the coating solvent but also in preventing blurring of the thermal transfer dyed image. An effect is obtained. Specific examples of the swellable inorganic layered compound include graphite, phosphate derivative compounds (such as zirconium phosphate compounds), chalcogenides, hydrotalcite compounds, lithium aluminum composite hydroxides, clay minerals (for example, Synthetic mica, synthetic smectite, smectite group, vermiculite group, mica group, etc.).

In addition to natural products (clay minerals), these swellable inorganic layered compounds may be either synthetic products or processed products (for example, surface treatment products of silane coupling agents). For example, fluorine phlogopite mica (KMg ₃ AlSi ₃ O ₁₀ F, melting method or solid phase reaction method), potassium tetrasilicon mica (KMg _2.5 Si ₄ O ₁₀ F ₂ , melting method), sodium tetrasilicon mica (NaMg _2.5 Si Synthetic mica such as ₄ O ₁₀ F ₂ (melting method), sodium teniolite (NaMg ₂ LiSi ₄ O ₁₀ F ₂ , melting method), lithium teniolite (LiMg ₂ LiSi ₄ O ₁₀ F ₂ , melting method), or Sodium hectorite (Na _0.33 Mg _2.67 Li _0.33 Si _4.0 O ₁₀ (OH or F) ₂ , hydrothermal reaction method or melting method), lithium hectorite (Na _0.33 Mg _2.67 Li _0.33 Si _4.0 O ₁₀ Synthetic smectites such as (OH or F) ₂ , hydrothermal reaction method or melting method) and saponite (Na _0.33 Mg _2.67 AlSi _4.0 O ₁₀ (OH) ₂ , hydrothermal reaction method) are more preferably used. Among these, sodium tetrasilicon mica is particularly preferable, and a desired particle size, aspect ratio, and crystallinity can be obtained by a fusion synthesis method.

  Examples of commercially available clay minerals include natural bentonite commonly called sodium bennite, kunipia (: trade name, natural montmorillonite, manufactured by Kunimine Industries), smecton (: trade name, hydrothermal reaction method synthetic smectite, kunimine). Kogyo Co., Ltd.), Bee Gum (: trade name, manufactured by Vanderbilt), Laponite (: trade name, manufactured by Laporte), DM Clean A, DMA-350, Na-Ts (: Trade name, all three types are synthesized by melt method Mica, sodium tetrasilicon mica, manufactured by Topy Industries, Ltd.), Bengel (: trade name, manufactured by Toyoshun Yoko Co., Ltd.), and the like. ,

  As the swellable inorganic layered compound, those having an aspect ratio of 5 to 5,000 are preferably used, more preferably the aspect ratio is in the range of 100 to 5,000, and particularly preferably 500 to 5,000. It is a range. If the aspect ratio is less than 5, blurring of the image may occur. On the other hand, if the aspect ratio exceeds 5,000, the uniformity of the image may be inferior. The aspect ratio (Z) is indicated by the relationship Z = L / a, and L is the average particle diameter in water of the swellable inorganic layered compound (measured by laser diffraction method. Particle size distribution meter LA- manufactured by HORIBA, Ltd. 910, volume distribution 50% median diameter), and a is the thickness of the swellable inorganic layered compound.

  The thickness a of the swellable inorganic layered compound is a value obtained by observing a cross section of the barrier layer with a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The particle average major axis of the swellable inorganic layered compound is 0.1 to 100 μm, preferably 0.3 to 50 μm, and more preferably 0.5 to 20 μm. When the average particle major axis is less than 0.1 μm, the aspect ratio becomes small, and it becomes difficult to spread in parallel on the intermediate layer, so that the image blur cannot be completely prevented. If the average particle major axis exceeds 100 μm, the swellable inorganic layered compound protrudes from the barrier layer, and irregularities are generated on the surface of the barrier layer, the smoothness of the surface of the receiving layer is lowered, and the image quality is deteriorated.

  In addition, in the intermediate layer and the barrier layer, in order to provide concealability and whiteness, and to improve the texture of the receiving sheet, as an inorganic pigment, calcium carbonate, titanium dioxide, zinc oxide, aluminum hydroxide, barium sulfate, barium dioxide, White inorganic pigments such as silicon, aluminum oxide, talc, kaolin, diatomaceous earth, and satin white, fluorescent dyes, and the like may be included.

  The barrier layer of the present invention is preferably formed using an aqueous coating solution. This aqueous coating solution is an aqueous solution of a water-soluble resin, or an emulsion or dispersion of various resins. In order to prevent the swelling and dissolution of hollow particles, the aqueous coating solution is a ketone solvent such as methyl ethyl ketone, an ester solvent such as ethyl acetate, a lower alcohol solvent such as methyl alcohol or ethyl alcohol, or a hydrocarbon solvent such as toluene or xylene. It is preferable not to contain an organic solvent such as a high boiling point and high polarity solvent such as a solvent, DMF or cellosolve.

The solid content coating amount of the barrier layer is preferably in the range of 0.5 to 8 g / m ² , more preferably 1 to 7 g / m ² , and particularly preferably 1 to 6 g / m ² . Incidentally, when the barrier layer solid content coating amount is less than 0.5 g / m ² , the barrier layer may not completely cover the surface of the intermediate layer, and the organic solvent permeation preventing effect may be insufficient. On the other hand, when the coating amount of the barrier layer solid content exceeds 8 g / m ² , the coating effect is saturated and uneconomical. May not be sufficiently exhibited, and the image density may be lowered.

(Receptive layer)
In the receiving sheet of the present invention, a receiving layer is provided on the barrier layer. The receiving layer itself may be a known dye thermal transfer receiving layer. As the resin for forming the receiving layer, a resin having a high affinity for the dye that migrates from the ink ribbon and therefore having a good dyeing property is used. Examples of such dye-dyeable resins include polyester resins, polycarbonate resins, polyvinyl chloride resins, vinyl chloride-vinyl acetate copolymer resins, polyvinyl acetal resins, polyvinyl butyral resins, polystyrene resins, polyacrylate resins, and cellulose. Examples thereof include cellulose derivative resins such as acetate butyrate, thermoplastic resins such as polyamide resin, and active energy ray curable resins. These resins preferably have a functional group reactive with the crosslinking agent used (for example, a functional group such as a hydroxyl group, an amino group, a carboxyl group, or an epoxy group).

  In order to prevent the receiving layer and the ink ribbon from being fused by heating with a thermal head during printing, one or more of a crosslinking agent, a release agent, a slipping agent, etc. are added to the receiving layer. It is preferable that it is mix | blended as an agent. Furthermore, if necessary, one or more of fluorescent dyes, plasticizers, antioxidants, pigments, fillers, ultraviolet absorbers, light stabilizers, antistatic agents, and the like may be added to the receiving layer. . These additives may be mixed with the forming component of the receiving layer before coating, or may be coated on and / or under the receiving layer as a coating layer different from the receiving layer.

The receiving layer is formed by preparing a coating solution for the receiving layer by appropriately dissolving or dispersing necessary additives such as a dye dyeing resin and a release agent in an organic solvent, and using a known coater. Then, on a sheet-like support provided with an intermediate layer (or barrier layer), after coating and drying, it can be heated and cured as necessary.
The solid coating amount of the receiving layer is preferably 1 to 12 g / m ² , more preferably 3 to 10 g / m ² . Incidentally, if the solid coating amount of the receiving layer is less than 1 g / m ² , the receiving layer may not completely cover the surface of the lower layer (intermediate layer, barrier layer, etc.), leading to deterioration in image quality. In some cases, a fusing trouble that the receiving layer and the ink ribbon adhere to each other due to heating by the thermal head may occur. On the other hand, if the solid content coating amount exceeds 12 g / m ² , the coating effect is saturated and uneconomical, and the coating strength of the receiving layer is insufficient, or the coating thickness becomes excessive. As a result, the heat insulation effect of the intermediate layer is not sufficiently exhibited, and the image density may be lowered.

(Back layer)
In the receiving sheet of the present invention, a back surface layer containing a polymer resin as a main component may be provided on the back surface (the surface opposite to the side on which the receiving layer is provided) of the sheet-like support. For the back layer, a back layer forming resin effective as an adhesive is used. This resin is effective in improving the adhesive strength between the back surface layer and the support, print transportability of the receiving sheet, preventing scratches on the receiving layer surface, and preventing dye transfer to the back layer contacting the receiving layer surface. As such a resin, an acrylic resin, an epoxy resin, a polyester resin, a phenol resin, an alkyd resin, a urethane resin, a melamine resin, a polyvinyl acetal resin, and a reaction cured product of these resins can be used. Moreover, in order to improve the adhesiveness of a sheet-like support body and a back surface layer, you may mix | blend a crosslinking agent, such as a polyisocyanate compound and an epoxy compound, in the back surface coating liquid for a back surface layer suitably.

  A conductive agent such as a conductive polymer or a conductive inorganic pigment may be added to the back layer in order to improve print transportability and prevent static electricity. As the conductive polymer, a cationic conductive polymer compound (for example, polyethyleneimine, an acrylic polymer containing a cationic monomer, a cation-modified acrylamide polymer, and a cationic starch) is particularly preferably used.

  An organic or inorganic filler can be mix | blended with a back surface layer as a friction coefficient modifier as needed. As the organic filler, nylon filler, cellulose filler, urea resin filler, styrene resin filler, acrylic resin filler, and the like can be used. As the inorganic filler, silica, barium sulfate, kaolin, clay, talc, heavy calcium carbonate, light calcium carbonate, titanium oxide, zinc oxide and the like can be used.

  The back surface layer may contain an anti-fusing agent such as a release agent and a lubricant as necessary. For example, examples of the release agent include silicone compounds such as non-modified and modified silicone oils, silicone block copolymers, and silicone rubbers, and examples of the lubricant include phosphate ester compounds, fatty acid ester compounds, and fluorine compounds. Conventionally known antifoaming agents, dispersants, colored pigments, fluorescent dyes, fluorescent pigments, ultraviolet absorbers and the like may be appropriately selected and used.

The solid content coating amount of the back layer is preferably in the range of 0.3 to 10 g / m ² . More preferably, it is 1-8 g / m < ² >. When the back layer solid content coating amount is less than 0.3 g / m ² , the scratch resistance when the receiving sheet is rubbed is not sufficiently exhibited, and a coating defect occurs to increase the surface electrical resistance value. There is. On the other hand, if the solid content coating amount exceeds 10 g / m ² , the effect is saturated and uneconomical.

(Undercoat layer)
In the receiving sheet of the present invention, an undercoat layer mainly composed of a polymer resin may be provided between the support and the intermediate layer. With this undercoat layer, even when the intermediate layer coating liquid is applied onto the support, the intermediate layer can be formed in a desired thickness without the coating liquid penetrating into the support. . Examples of the polymer resin used for the undercoat layer include acrylic resins, polyurethane resins, polyester resins, polyolefin resins, and modified resins thereof.

For example, when a paper base material is used as a support in the present invention, when an undercoat layer made of an aqueous coating solution is applied, the paper base material is wrinkled due to uneven water absorption on the paper base material surface. Swelling may occur, adversely affecting the texture and printability. Therefore, it is preferable to use a coating solution in which a polymer resin is dissolved or dispersed in an organic solvent, not an aqueous coating solution. Usable organic solvents include common organic solvents such as toluene, methyl ethyl ketone, isopropyl alcohol, and ethyl acetate.
For the undercoat layer, titanium dioxide, calcium carbonate, barium sulfate, etc. are used to improve the coatability of the undercoat layer coating solution itself, improve the adhesion to the support and the intermediate layer, and improve the whiteness of the receiving sheet. A white inorganic pigment may be added.

The solid coating amount of the undercoat layer is preferably in the range of 1 to ²⁰ g / m2. If the solid content coating amount is less than 1 g / m ² , the effect of the undercoat layer may not be obtained. If the solid content coating amount exceeds 20 g / m ² , the effect becomes saturated and uneconomical. The texture of the sheet as paper may be lost, which is not preferable.

  In the present invention, the intermediate layer, the receiving layer, and other coating layers are formed according to a conventional method, and each prepares a coating solution containing necessary components, and is a bar coater, gravure coater, comma coater, blade coater, air A known coater such as a knife coater, a gate roll coater, a die coater, a curtain coater, a lip coater, and a slide bead coater may be used for coating on a sheet-like support and drying.

  The present invention will be described in detail by the following examples, but the scope of the present invention is not limited thereto. In the examples, “%” and “parts” indicate “mass%” and “parts by mass” of solids, except for those relating to solvents.

Example 1
"Formation of an intermediate layer"
As the sheet-like support, art paper having a thickness of 150 μm (trade name: OK Kanto N, 174.4 / m ² , manufactured by Oji Paper Co., Ltd.) is used, and the intermediate layer coating liquid-1 having the following composition is applied on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 48 μm.
Intermediate layer coating solution-1
Hollow particles A: foamed hollow particles mainly composed of polyacrylonitrile (average particle size 3.8 μm, particle size variation coefficient 14%, volume hollowness 75%) 65 parts hollow particles B: microcapsule type hollow particles (trade name: Nipol MH-5055,
(Manufactured by ZEON, average particle size 0.55μm, particle size variation coefficient 15%, volume hollowness 55%)
0.5 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 24.5 parts water 200 parts

"Formation of thermal transfer receiving sheet"
Furthermore, the barrier layer coating liquid-1 having the following composition was applied on the intermediate layer so that the solid content coating amount was 2 g / m ² and dried to form a barrier layer, and further on the barrier layer. The receiving layer coating liquid-1 having the following composition was applied and dried so that the solid content coating amount was 5 g / m ² , and then cured at 50 ° C. for 72 hours to form a receiving layer. Further, the back layer coating liquid-1 having the following composition was applied to the opposite side of the receiving layer coated surface of the sheet-like support so that the solid content coating amount was 3 g / m ² and dried to form the back layer. Formed to obtain a receiving sheet.
Coating liquid for barrier layer-1
Swellable inorganic layered compound (sodium 4 silicon mica,
Particle average major axis 6.3 μm, aspect ratio 2700) 30 parts polyvinyl alcohol (trade name: PVA105, manufactured by Kuraray) 50 parts styrene-butadiene latex (trade name: L-1537, manufactured by Asahi Kasei) 20 parts water 1100 parts
Receiving layer coating solution-1
Polyester resin (trade name: Byron 200, manufactured by Toyobo) 100 parts silicone oil (trade name: KF393, manufactured by Shin-Etsu Chemical Co., Ltd.) 3 parts polyisocyanate (trade name: Takenate D-140N, manufactured by Takeda Pharmaceutical Co., Ltd.) 5 parts Toluene / Methyl ethyl ketone = 1/1 (mass ratio) mixture 400 parts
Back layer coating solution-1
Polyvinyl acetal resin (trade name: ESREC KX-1, manufactured by Sekisui Chemical Co., Ltd.) 45 parts polyacrylic acid ester resin (trade name: Julimer AT613, manufactured by Nippon Pure Chemical Industries) 25 parts nylon resin particles (trade name: MW330, manufactured by Shinto Fine) ) 10 parts zinc stearate (trade name: Z-7-30, manufactured by Chukyo Yushi) 10 parts cationic conductive agent (trade name: Chemistat 9800, manufactured by Sanyo Kasei) 10 parts water / isopropyl alcohol = 2/3 (mass ratio) ) 400 parts of liquid mixture

Example 2
A receiving sheet was obtained in the same manner as in Example 1 except that “Formation of intermediate layer” was changed as follows.
"Formation of an intermediate layer"
As the sheet-like support, art paper (trade name: OK Kanto N, 174.4 / m ² , manufactured by Oji Paper Co., Ltd.) having a thickness of 150 μm is used, and an intermediate layer coating liquid-2 having the following composition is formed on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 48 μm.
Intermediate layer coating liquid-2
Hollow particles A: Expanded hollow particles mainly composed of polyacrylonitrile (average particle diameter 3.8 μm, particle diameter variation coefficient 14%, volume hollow ratio 75%) 65 parts hollow particles B: microcapsule type hollow particles (trade name: Ropeke HP-1055, manufactured by Rohm and Haas, average particle size 1.0μm, particle size variation coefficient 12%, volume hollowness 55%)
3 parts polyvinyl alcohol (trade name: PVA205, made by Kuraray) 10 parts styrene-butadiene latex (trade name: PT1004, made by Nippon Zeon) 22 parts water 200 parts

Example 3
A receiving sheet was obtained in the same manner as in Example 1 except that “intermediate layer formation” was changed as follows.
"Formation of an intermediate layer"
As a sheet-like support, art paper having a thickness of 150 μm (trade name: OK Kanto N, 174.4 / m ² , manufactured by Oji Paper Co., Ltd.) was used, and an intermediate layer coating solution-3 having the following composition was applied on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 48 μm.
Intermediate layer coating solution-3
Hollow particles A: foamed hollow particles mainly composed of polyacrylonitrile (average particle size 3.8 μm, particle size variation coefficient 14%, volume hollowness 75%) 65 parts hollow particles B: microcapsule type hollow particles (trade name: Ropeke HP-1055, manufactured by Rohm and Haas, average particle size 1.0μm, particle size variation coefficient 12%, volume hollowness 55%)
0.6 part polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 24.4 parts water 200 parts

Example 4
A receiving sheet was obtained in the same manner as in Example 2 except that the barrier layer coating solution-2 was used instead of the barrier layer coating solution-1.
Coating liquid for barrier layer-2
Swellable inorganic layered compound (sodium 4 silicon mica, particle average major axis 2.0 μm,
Aspect ratio 300) 30 parts polyvinyl alcohol (trade name: PVA105, manufactured by Kuraray Co., Ltd.) 50 parts styrene-butadiene latex (trade name: L-1537, manufactured by Asahi Kasei) 20 parts water 1100 parts

Example 5
A receiving sheet was obtained in the same manner as in Example 1 except that “intermediate layer formation” was changed as follows.
"Formation of an intermediate layer"
As a sheet-like support, art paper (trade name: OK Kanto N, 127.9 / m ² , manufactured by Oji Paper Co., Ltd.) having a thickness of 105 μm was used, and an intermediate layer coating liquid-4 having the following composition was applied on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 100 μm.
Intermediate layer coating solution-4
Hollow particles A: Expanded hollow particles (trade name: EXPANCEL 551DE20, manufactured by Nippon Philite Co., Ltd., average particle diameter 20 μm, particle diameter variation coefficient 5%, volume hollowness 94%) 40 parts hollow particles B: polyacrylonitrile as a main component Expanded hollow particles (average particle size 3.8 μm, particle size variation coefficient 14%, volume hollowness 75%) 1.5 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts styrene-butadiene latex (trade name) : PT1004, manufactured by Nippon Zeon) 48.5 parts 200 parts water

Example 6
A receiving sheet was obtained in the same manner as in Example 1 except that “intermediate layer formation” was changed as follows.
"Formation of an intermediate layer"
As a sheet-like support, art paper (trade name: OK Kanto N, 127.9 / m ² , manufactured by Oji Paper Co., Ltd.) having a thickness of 105 μm was used, and an intermediate layer coating solution-5 having the following composition was applied on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 100 μm.
Intermediate layer coating solution-5
Hollow particles A: Expanded hollow particles (trade name: EXPANCEL 551DE20, manufactured by Nippon Philite Co., Ltd., average particle diameter 20 μm, particle diameter variation coefficient 5%, volume hollowness 94%) 40 parts hollow particles B: polyacrylonitrile as a main component Expanded hollow particles (average particle size 5.4 μm, particle size variation coefficient 10%, volume hollowness 80%) 3.5 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts styrene-butadiene latex (trade name) : PT1004, manufactured by Zeon Corporation) 46.5 parts 200 parts water

Example 7
A receiving sheet was obtained in the same manner as in Example 1 except that “intermediate layer formation” was changed as follows.
"Formation of an intermediate layer"
As a sheet-like support, art paper having a thickness of 105 μm (trade name: OK Kanto N, 127.9 / m ² , manufactured by Oji Paper Co., Ltd.) was used, and an intermediate layer coating solution-6 having the following composition was applied on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 93 μm.
Intermediate layer coating solution-6
Hollow particle A: Foamed composite hollow particle (main component of shell: polyacrylonitrile, shell surface coated with calcium carbonate powder, average particle size 20 μm, particle size variation coefficient 5%, volume hollowness 90%,
Particle density 0.2 g / cm ³ ) 45 parts hollow particle B: microcapsule type hollow particle (trade name: Honen Microsphere MB
-925, manufactured by Hornen Corporation, average particle diameter 5 μm, particle diameter variation coefficient 11%,
Volumetric hollowness 35%) 3.5 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 41.5 parts water 200 parts

Comparative Example 1
A receiving sheet was obtained in the same manner as in Example 1 except that “intermediate layer formation” was changed as follows.
"Formation of an intermediate layer"
As a sheet-like support, art paper (trade name: OK Kanto N, 127.9 / m ² , manufactured by Oji Paper Co., Ltd.) having a thickness of 105 μm was used, and an intermediate layer coating solution-7 having the following composition was applied on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 108 μm.
Intermediate layer coating solution -7
Hollow particle A: Expanded hollow particle (trade name: EXPANCEL 091DE, manufactured by Nippon Philite Co., Ltd.,
Average particle size 40 μm, particle size variation coefficient 4%, volume hollowness 97%) 30 parts hollow particles B: expanded hollow particles mainly composed of polyacrylonitrile (average particle size 3.8 μm, particle size variation coefficient 14%, volume) Hollow ratio 75%) 0.3 part polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 59.7 parts water 200 parts

Comparative Example 2
A receiving sheet was obtained in the same manner as in Example 1 except that “intermediate layer formation” was changed as follows.
"Formation of an intermediate layer"
As the sheet-like support, art paper having a thickness of 150 μm (trade name: OK Kanto N, 174.4 / m ² , manufactured by Oji Paper Co., Ltd.) was used, and an intermediate layer coating solution-8 having the following composition was applied on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 51 μm.
Intermediate layer coating solution-8
Hollow particle A: Microcapsule type hollow particle (trade name: Ropeque HP-1055, manufactured by Rohm and Haas, average particle size 1.0 μm, particle size variation coefficient 12%, volume hollowness 55%)
60 parts hollow particles B: microcapsule type hollow particles (trade name: SX863A, manufactured by Nippon Synthetic Rubber,
Average particle size 0.4 μm, particle size variation coefficient 13%, volume hollowness 30%) 8 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 22 200 parts water

Comparative Example 3
A receiving sheet was obtained in the same manner as in Example 1 except that “intermediate layer formation” was changed as follows.
"Formation of an intermediate layer"
As a sheet-like support, art paper (trade name: OK Kanto N, 127.9 / m ² , manufactured by Oji Paper Co., Ltd.) having a thickness of 105 μm was used, and an intermediate layer coating liquid-9 having the following composition was applied on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 93 μm.
Intermediate layer coating solution-9
Hollow particles A: Expanded hollow particles (trade name: EXPANCEL 551DE20, manufactured by Nippon Philite Co., Ltd., average particle diameter 20 μm, particle diameter variation coefficient 5%, volume hollowness 94%) 40 parts hollow particles B: polyacrylonitrile as a main component Expanded hollow particles (average particle size 10 μm, particle size variation coefficient 10%, volume hollowness 80%) 22 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts styrene-butadiene latex (trade name: PT1004, Japan) Zeon) 28 parts water 200 parts

Comparative Example 4
A receiving sheet was obtained in the same manner as in Example 1 except that “intermediate layer formation” was changed as follows.
"Formation of an intermediate layer"
As a sheet-like support, art paper (trade name: OK Kanto N, 127.9 / m ² , manufactured by Oji Paper Co., Ltd.) having a thickness of 105 μm was used, and an intermediate layer coating liquid-10 having the following composition was applied on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 95 μm.
Intermediate layer coating solution-10
Hollow particles A: Expanded hollow particles (trade name: EXPANCEL 461DE, manufactured by Nippon Philite Co., Ltd.,
(Average particle size 30 μm, particle size variation coefficient 4%, volume hollowness 94%) 30 parts hollow particles B: microcapsule type hollow particles (trade name: Ropeke HP-1055, manufactured by Rohm and Haas, average particle size 1.0 μm , Particle diameter variation coefficient 12%, volume hollowness 55%)
0.01 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 60 parts water 200 parts

Comparative Example 5
A receiving sheet was obtained in the same manner as in Example 1 except that “intermediate layer formation” was changed as follows.
"Formation of an intermediate layer"
As a sheet-like support, art paper (trade name: OK Kanto N, 174.4 / m ² , manufactured by Oji Paper Co., Ltd.) having a thickness of 150 μm is used, and an intermediate layer coating liquid-11 having the following composition is applied on one side thereof. The intermediate layer was formed by coating and drying so that the thickness after drying was 49 μm.
Intermediate layer coating solution-11
Hollow particles A: foamed hollow particles mainly composed of polyacrylonitrile (average particle size 3.8 μm, particle size variation coefficient 14%, volume hollowness 75%) 65 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts Styrene-butadiene latex (trade name: PT1004, manufactured by Zeon Corporation) 25 parts Water 200 parts

Evaluation The receiving sheets obtained in each of the above examples and comparative examples were evaluated by the following methods, and the results obtained are shown in Table 1.

"Print quality" (print density, image uniformity)
Using a commercially available thermal transfer video printer (trade name: DPP-SV55, manufactured by Sony Corporation), an ink layer containing sublimation dyes of yellow, magenta, and cyan with a binder on a 6 μm thick polyester film Using an ink ribbon provided in a surface sequential manner, the ink layer of each color is brought into contact with the surface of the receiving sheet, and heating is controlled stepwise by a thermal head, whereby a predetermined image is thermally transferred to the receiving sheet, Halftone single color and color overlay images were printed.

About the recording image according to the applied energy transcribe | transferred on the receiving sheet, the reflection density was measured using the Macbeth reflection densitometer (brand name: RD-914, Kollmorgen company make). The density of the high gradation portion corresponding to the 15th step from the lowest applied energy is displayed in Table 1 as the print density. If the print density is 2.0 or more, it is sufficiently suitable for practical use.
Furthermore, the uniformity of the recorded image of the gradation portion corresponding to an optical density (black) of 0.3 was visually evaluated for the presence or absence of shading unevenness and white spots. Excellent evaluation results were indicated by ◎, good ones by ◯, light unevenness and some white spots were indicated by Δ, and white spots and white defects were marked by x.

"Recess of receiving sheet"
A commercially available thermal transfer video printer (trade name: M1, manufactured by Sony Corporation) was modified to increase the nip pressure of the transport roll. The nip pressure measured using a pressure test film (trade name: Prescale, manufactured by Fuji Photo Film Co., Ltd.) was 50 kg / cm ² . Using this testing machine, the dent of the receiving sheet by the transport roll was visually evaluated.
The case where the dent was not visible at all was marked with 、, the case where the dent was hardly visible was marked with ○, and the case where the dent was remarkable was marked with ×.

“Preservation after printing” (Blending of images)
Using a commercially available thermal transfer video printer (trade name: DPP-SV55, manufactured by Sony Corporation), an ink layer containing sublimable dyes of yellow, magenta, and cyan with a binder is coated on a 6 μm thick polyester film. Using the ink ribbons provided in sequence, the ink layer of each color is brought into contact with the surface of the receiving sheet, and by applying heat controlled stepwise with a thermal head, a predetermined image is thermally transferred to the receiving sheet, black and A blue thin line image was printed. Next, as a test for promoting the storage stability after printing, a sheet on which an image was printed was left for 2 weeks in an environment of a temperature of 50 ° C. and a relative humidity of 95%.
The blur rate of the image was calculated according to the following formula.
Bleeding rate = (thickness of fine lines after being left / thickness of fine lines before being left) x 100
The smear rate was evaluated as ○ when less than 110%, Δ when 110% or more and less than 130%, and × when 130% or more.
The above evaluation is sufficiently suitable for practical use if it is above the ○ level.

The receiving sheet of the present invention is particularly suitable for a dye thermal transfer printer, has sufficient strength against compression of the receiving sheet, does not cause dents in the receiving sheet, provides a high print density and a good uniform image, and is low in cost. The thermal transfer receiving sheet is practically extremely valuable.

Claims (4)

In a thermal transfer receiving sheet in which an intermediate layer containing hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support, the intermediate layer has two types of hollow particles A and hollow particles B having different average particle diameters. containing the door, it meets the average as the average particle diameter L _a of each of the hollow particles ([mu] m) particle size L _B ([mu] m) and satisfies the following relational expression (1) to (3) simultaneously, the intermediate layer and the image-receiving A thermal transfer receiving sheet , further comprising a barrier layer mainly composed of a water-soluble resin and / or a water-dispersible resin, between the layers .
L _A = 2 to 35 μm (1)
L _B = 0.2 to 9 μm (2)
0.05 ≦ L _B / L _A ≦ 0.4 (3) The thermal transfer receiving sheet according to claim 1, wherein the coefficient of variation of each of the average particle diameter L _A and the average particle diameter L _B is 35% or less.   The thermal transfer receiving sheet according to claim 1 or 2, wherein the hollow particle A has a volume hollow ratio of 60 to 97%, and the hollow particle B has a volume hollow ratio of 30 to 97%. The barrier layer further contains a swellable inorganic layered compound, the particle average major axis of the swellable inorganic layered compound is 0.1 to 100 μm, and the aspect ratio (ratio of particle mean major axis / thickness of layered compound) ) Is 5 to 5,000. The thermal transfer receiving sheet according to any one of claims 1 to 3 .