JP2006248212A - Thermal transfer accepting sheet, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer accepting sheet of a high picture quality and a low cost which does not use an expensive synthetic paper or an expanded film, does not have unevenness in printed images resulting from a supporting body, in the accepting sheet which is suitable to a dye thermal transfer printer, and for which an intermediate layer containing hollow particles is provided, and to provide its manufacturing method. <P>SOLUTION: At least on one surface of a sheet-like supporting body of which the main component is cellulose pulp, the intermediate layer containing the hollow particles and an image accepting layer are formed in order for this thermal transfer accepting sheet. In the thermal transfer accepting sheet, the air permeability of the sheet-like supporting body based on the JAPAN TAPPI No.5-2 is from 100 seconds to less than 1,000 seconds. The manufacturing method for the same is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermal transfer receiving sheet used in a printer that forms an image by superimposing an ink ribbon and using a thermal head as a device to thermally transfer a colorant of the ink ribbon. More specifically, the present invention is suitable for thermal printers, particularly dye thermal transfer printers, is low-cost, has a high density similar to silver salt photography, and can provide an image having excellent uniformity. The present invention relates to a thermal transfer receiving sheet having a layer (hereinafter also simply referred to as a receiving sheet) and a method for producing the same.

  In recent years, dye thermal transfer printers that can print particularly clear full-color images have attracted attention as thermal printers. In a dye thermal transfer printer, a dye layer containing a dye of an ink ribbon and an image receiving layer (hereinafter also simply referred to as a receiving layer) containing a dye-stainable resin of a receiving sheet are superposed and supplied from a thermal head or the like. An image is formed by transferring the dye at a required portion of the dye layer by a predetermined concentration onto the receiving layer by heat. The ink ribbon is composed of dye layers 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.

  In dye thermal transfer printers, with the development of computerized digital image processing technology, the resulting images have improved dramatically, and the thermal transfer system is expanding its market. With the improvement of thermal head technology and the development of temperature control technology, there is an increasing demand for high speed and high sensitivity printing systems. Therefore, an important technical issue is how to efficiently use the amount of heat generated by a heating device such as a thermal head for image formation. In addition, in order to reduce the price of the printer and simplify the structure, it is a technical problem to reduce the pressure of the thermal head during printing and to further extend the life of the head. Currently, printers that can print one A6 size sheet in 30 seconds or less are on the market, and it is expected that the demand for higher printing speed will increase in the future.

In order to efficiently form a high-quality, high-density image on a receiving sheet, a receiving layer mainly composed of a dye-dyeable resin is provided on the support, but as a support substrate of the receiving sheet, Although the film is excellent in smoothness, the heat from the thermal head is dissipated to the base material, resulting in insufficient sensitivity, and since the film has no cushioning property, the adhesion between the ink ribbon and the receiving sheet is not sufficient, There is a drawback that density unevenness occurs.
In order to solve this problem, as a support, a support having a plastic film bonded to a core layer such as paper (see, for example, Patent Document 1), a thermoplastic resin such as a polyolefin resin as a main component, a void A support in which a biaxially stretched film (synthetic paper) including a (void) structure is bonded to a core material layer such as paper has been proposed (see, for example, Patent Document 2). However, although the receiving sheet using these supports is excellent in heat insulation and smoothness, there are disadvantages such as lack of paper-like texture and high cost.

In addition, when ordinary paper is used as the support substrate of the receiving sheet, the sensitivity is not as good as the film, and the cushioning property is slightly better than the film, but the adhesion unevenness between the ink ribbon and the receiving layer due to the uneven density of the paper fibers. Therefore, there is a disadvantage that unevenness of density of the print occurs. In order to solve such problems, a receiving sheet is disclosed in which an intermediate layer containing hollow particles is provided between a sheet-like support such as paper and a receiving layer (see, for example, Patent Documents 3 and 4). .)
The sensitivity of these receiving sheets is improved by the effect of improving the heat insulating property and cushioning property of the hollow particle-containing layer, but the surface of the receiving sheet is likely to be uneven due to the influence of the hollow particles, and the uniformity of the image is poor. There's a problem. Also, when forming the hollow particle-containing layer, it is formed by applying and drying an aqueous coating solution, so that the paper absorbs water and swells due to the influence of water used as a solvent, and the unevenness of the paper There is also a variation in basis weight, etc., and unevenness is likely to occur on the surface of the receiving sheet. This unevenness causes white spots in the printed image, resulting in poor image uniformity, and suppresses swelling due to water absorption of papers. It has been demanded.

Regarding the improvement of the unevenness of the surface of the receiving sheet, for example, a receiving sheet having a specific surface roughness, glossiness, etc. has been proposed by defining the average particle diameter and hollow ratio of the hollow particles used in the intermediate layer (for example, (See Patent Documents 5 and 6.) Further, in a method for producing a receiving sheet in which a resin layer such as a bubble layer and a receiving layer is sequentially formed on a commonly used paper substrate or film, a smoothing treatment is applied to the bubble layer and / or the receiving layer. A receiving sheet with improved smoothness on the surface of the receiving layer has been proposed (see, for example, Patent Document 7). Furthermore, a receiving sheet having a heat insulating layer containing hollow particles on a paper base having an air permeability of 1000 to 3500 seconds has been proposed (for example, see Patent Document 8).
However, in the case of the receiving sheet as described above, when the receiving layer is coated on the intermediate layer containing the hollow particles and formed by drying, there is a tendency to cause surface defects due to blistering, etc. However, it is difficult to make the recording surface sufficiently uniform. In particular, when printing is performed with a high-speed, low-printing pressure printer such as the present, image quality and image uniformity are lowered, and improvement is required.

JP 61-197282 A (first page) JP-A-62-198497 (first page) Japanese Unexamined Patent Publication No. 64-27996 (first page) JP 63-87286 A (first page) JP-A-9-99651 (page 1-5) JP 2001-39043 A (page 2-3) JP-A-6-210968 (page 2-4) Japanese Patent Laying-Open No. 2004-9572 (page 2-3)

  The present invention has been made in view of the circumstances as described above, and solves the above-mentioned problems of conventional receiving sheets, and is particularly suitable for dye thermal transfer printers, and is provided with an intermediate layer containing hollow particles. Therefore, an object of the present invention is to provide a low-cost, high-quality receiving sheet free from uneven printing due to a support and a method for producing the same without using expensive synthetic paper or foamed film.

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-shaped support mainly composed of cellulose pulp, the JAPAN TAPPI No5-2 of the sheet-shaped support A thermal transfer receiving sheet characterized in that the air permeability based on is 100 seconds or more and less than 1000 seconds.
(2) The thermal transfer receiving sheet according to item (1), wherein the hollow particles have an average particle diameter of 0.2 to 15 μm and a volume hollowness of 25 to 97%.
(3) The thermal transfer receiving sheet according to (1) or (2), wherein the sheet-like support contains a wet strength enhancer of 0.1 to 5% by mass with respect to the cellulose pulp solid content.

(4) In a method for producing 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 mainly composed of cellulose pulp, the JAPAN TAPPI of the sheet-like support is used. The air permeability based on No. 5-2 is 100 seconds or more and less than 1000 seconds, and at least one surface of the sheet-like support is coated with an intermediate layer coating solution containing hollow particles and dried to form an intermediate layer. A method for producing a thermal transfer receiving sheet, characterized by performing a smoothing treatment after forming and / or after forming an image receiving layer.
(5) The method for producing a thermal transfer receiving sheet according to (4), wherein the sheet-like support contains a wet strength enhancer of 0.1 to 5% by mass with respect to cellulose pulp solid content.
(6) The method for producing a thermal transfer receiving sheet according to (4) or (5), wherein a thickness restoration process is further performed after the smoothing process.

  The receiving sheet of the present invention is suitable for a dye thermal transfer printer, is improved in density unevenness, white spot and the like, can be recorded at low cost with high sensitivity and high image quality, and is an extremely excellent receiving sheet.

The layer structure of the receiving sheet according to the present invention includes at least a sheet-like support mainly composed of cellulose pulp, an intermediate layer containing hollow particles, and a receiving layer. Furthermore, it is of course possible to improve the performance as a receiving sheet by appropriately providing coating layers such as an undercoat layer, a barrier layer, and a back layer.
These layers will be described in detail below.

(Sheet support)
As the sheet-like support used in the thermal transfer receiving sheet of the present invention, a paper base material mainly composed of cellulose pulp is used, and the air permeability based on JAPAN TAPPI No5-2 of the sheet-like support is 100 seconds. Those in the range of less than 1000 seconds are used, preferably in the range of 100 to 900 seconds, and more preferably in the range of 150 to 900 seconds.

  In the above sheet-like support, when the air permeability is less than 100 seconds, the penetration of the paint into the paper base material becomes excessive when the aqueous intermediate layer paint is applied and dried on the paper base material. Unevenness is generated, the surface flatness of the intermediate layer coating surface is lowered, and the uniformity of the obtained print image is deteriorated, which is not preferable. On the other hand, when the air permeability is 1000 seconds or more, for example, when a coating layer such as a barrier layer or a receiving layer is laminated on the intermediate layer, it is difficult for the solvent component of these coating layers to escape to the paper substrate side. For this reason, blisters are likely to be generated on the coating layer surfaces such as the barrier layer and the receiving layer, the flatness of the coating surface is lowered, and the uniformity of the printed image is lowered.

  The method for controlling the air permeability of the sheet-like support within a predetermined range is not particularly limited. For example, pulp used for paper substrate production is beaten under appropriate beating conditions, or a paper base is used with a size press device or the like. The air permeability can be controlled by appropriately selecting the type and amount of coating liquid to be applied to the surface of the material, and selecting the conditions for calendering to smooth the paper substrate. . In the coated paper, it is also possible to adjust the air permeability by appropriately selecting the type, shape, particle diameter, coating amount, etc. of the filler and pigment to be used.

  As the sheet-like support of the present invention, paper mainly composed of cellulose pulp is used, and includes, for example, fine paper, fine coated paper, coated paper, art paper, cast coated paper, and thermally expandable particles. Examples of the paper include foamed paper and paperboard. Of course, it is possible to perform a calendar process or the like on these papers to improve smoothness and adjust the air permeability. The above papers are preferably used because of their low heat shrinkability, good heat insulation, good texture as receiving paper, and low cost.

  In order to obtain a sheet-like support having the air permeability defined in the present invention, for example, a pulp slurry, a cationic compound, a cationic starch, a sizing agent having an effect in a weakly acidic to weakly alkaline pH region, and an anionic compound It can be produced by adding various usual paper additives.

  As the pulp used in the present invention, natural pulp and synthetic pulp such as softwood pulp, hardwood pulp, softwood hardwood mixed pulp, and mixed pulp of natural pulp and synthetic pulp can be used.

  In the present invention, as the cationic compound used, polyethyleneimine, polyethyleneimine-epichlorohydrin condensate, aminopolyamide epichlorohydrin resin, polyvinylpyridine, styrene-dimethylaminoethyl methacrylate copolymer, cationic polyurethane resin, urea formaldehyde resin, Melamine formaldehyde resin, dimethylamine epichlorohydrin resin, etc. are used.

Examples of the cationized starch used in the present invention include those obtained by reacting starch with ethylimine, those obtained by reacting starch and polyalkylene polyamine, and alkaline such as starch and 2-dimethylaminoethyl chloride. And those obtained by reacting various halogenated amines, and those obtained by reacting alkaline starch with quaternary ammonium such as 2,3-epoxypropyltrimethylammonium chloride.
In the present invention, the content of the cationized starch in the base paper is preferably in the range of 0.1 to 0.5% with respect to the pulp dry mass.

  The sizing agent used in the present invention is a sizing agent having an effect in a papermaking system having a pH of 5 to 9 and a weakly acidic or weakly alkaline PH region. Examples of such sizing agents include sizing agents composed of higher organic ketene dimers, substituted cyclic dicarboxylic acid anhydrides, epoxidized higher fatty acid amides, amide group-containing cationic sizing agents, and the like. These can be used alone or in combination of several kinds.

  In the present invention, the sizing agent addition amount in the base paper is preferably in the range of 0.1 to 2.0% with respect to the pulp dry weight.

  Examples of the anionic compound used in the present invention include an acrylamide homopolymer, a partial hydrolyzate of a copolymer of vinyl monomer and acrylamide copolymerizable with acrylamide, or maleic acid, acrylic acid or a salt thereof and acrylamide. Is a commonly used anionic polyacrylamide type paper strength enhancer such as a copolymer.

  The base paper of the present invention includes, in addition to the cationized starch and sizing agent, a wet paper strength enhancer such as polyamide polyamine epichlorohydrin, a dry paper strength enhancer such as polyacrylamide, and an antifoggant. Additives usually used in papermaking, such as pigments, dyes, and yield improvers, may be included.

  Further, in the present invention, examples of the wet strength enhancer include polyamide polyamine epichlorohydrin, urea formaldehyde resin, melamine formaldehyde resin, dialdehyde starch, and glyoxal-modified polyacrylamide. By adding these wet strength enhancers to the pulp, water-resistant bonds that are resistant to water are formed by the reaction of hydroxyl groups in the cellulose molecules with the resin or the formation of water-resistant bonds between the resins. It is thought that the strength is improved.

  Among the wet strength enhancers, polyamide polyamine epichlorohydrin, urea formaldehyde resin, and melamine formaldehyde resin are preferably used, and polyamide polyamine epichlorohydrin is particularly preferably used. The addition amount of the wet strength enhancer in the base paper is preferably in the range of 0.1 to 5% by mass, more preferably in the range of 0.2 to 4% by mass, even more preferably relative to the absolute dry mass of the pulp. Is in the range of 0.4 to 4 mass%.

  If necessary, surface treatment with starch, polyvinyl alcohol, gelatin or the like, and antistatic treatment with bow glass, sodium chloride, aluminum chloride or the like can be performed on the base paper.

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

  The sheet-like support used in the present invention preferably has a thickness of 50 to 300 μm. Incidentally, if the thickness 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 sufficient. There are some cases that cannot be prevented. On the other hand, if the thickness exceeds 300 μm, the thickness of the obtained receiving sheet becomes excessive, so that the capacity of the receiving sheet in the printer is reduced, or if the predetermined number of receiving sheets is stored, the volume of the printer In some cases, this causes an increase and makes it difficult to make the printer compact.

  Further, the sheet-like support used in the present invention preferably has a smoothness of 50 seconds or more measured according to JIS P 8119 on the side where the intermediate layer is provided. Incidentally, when the smoothness is less than 50 seconds, since the surface is rough, the thickness of the intermediate layer provided on the support becomes non-uniform, and there is a possibility of causing density unevenness in the printed image.

(Middle layer)
In the present invention, since the intermediate layer provided on the sheet-like support contains hollow particles, the compression elastic modulus of the receiving sheet can be reduced, and an appropriate degree of freedom of deformation can be imparted to the receiving sheet. Since the followability and adhesion of the receiving sheet to the shape and the ink ribbon shape are improved, the thermal efficiency of the thermal head to the receiving layer is improved even in a low energy state, the print density of the printed image is increased, and the image quality is improved. Can do. In addition, when the high-speed printer is applied with high energy, it is possible to simultaneously prevent printing defects due to ribbon wrinkles generated on the ink ribbon.

(Hollow particles)
The hollow particles used in the intermediate layer of the present invention are composed of a shell formed of a polymer material and one or more hollow (pore) parts surrounded by the shell, and its production method is exceptional. However, it can be selected from those manufactured as follows, for example.
(A) Expanded hollow particles produced by heating and foaming a thermoplastic polymer material containing a thermally expandable substance (hereinafter simply referred to as “foamed hollow particles”).
(B) 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. Obtained microcapsule-like hollow particles (hereinafter simply referred to as microcapsule-like hollow particles).

  In the intermediate layer of the present invention, pre-expanded hollow particles are preferably used. The foamed hollow particles include, for example, volatile low-boiling hydrocarbons such as n-butane, i-butane, pentane, and neopentane in a thermoplastic polymer material as a thermally expandable substance. It is obtained by using a homopolymer such as vinylidene chloride, vinyl chloride, acrylonitrile, methacrylonitrile, styrene, (meth) acrylic acid, (meth) acrylic ester, or a copolymer thereof as a shell (wall) material. The particles obtained are preliminarily heated to a predetermined particle size by subjecting them to a treatment such as heating.

  In addition, the foamed hollow particles as described above generally have a small specific gravity, and therefore, for the purpose of improving dispersibility and improving handling workability, inorganic powders such as calcium carbonate, talc, and titanium dioxide are thermally fused. Pre-foamed composite hollow particles that are adhered 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 microcapsule-like hollow particles preferably used in the intermediate layer of the present invention are obtained by a microcapsule-forming polymerization method, and are volatile in the core portion using a polymer-forming material (shell-forming material) as a shell (wall). A microcapsule containing a liquid (a pore forming material) is dried to volatilize and escape the pore forming material to form a hollow core portion. As the polymer-forming material, a hard resin such as a styrene- (meth) acrylic acid ester copolymer or a melamine resin is preferably used, and as the volatile liquid, for example, water is used.

  The average particle diameter of the hollow particles used in the present invention is preferably 0.2 to 15 μm, more preferably 0.3 to 10 μm, and most preferably 0.4 to 9 μm. When the average particle diameter of the hollow particles is less than 0.2 μm, the volumetric hollow ratio of the hollow particles is generally low, and thus the sensitivity improving effect of the receiving sheet may not be sufficiently exhibited. On the other hand, when the average particle diameter exceeds 15 μm, the smoothness of the obtained intermediate layer surface is lowered, the uniformity of the thermal transfer image becomes poor, and the gloss development property may be insufficient.

The maximum particle size of the hollow particles used in the present invention is preferably 40 μm or less, more preferably 35 μm or less. If the maximum particle diameter of the hollow particles exceeds 40 μm, unevenness in density of prints and white spots due to coarse particles may occur in the thermal transfer image, resulting in poor image quality. In order to prevent the hollow particles from containing coarse particles having a maximum particle size exceeding 40 μm, in the production of hollow particles generally exhibiting a normal distribution state, by adjusting the set value of the average particle size. It is possible to respond. Further, by providing a particle classification step, it is possible to reliably obtain hollow particles that do not contain coarse particles.
The average particle size of the hollow particles can be measured using a general particle size measuring device, and is measured using, for example, a laser diffraction type particle size distribution measuring device (trade name: SALD2000, manufactured by Shimadzu Corporation). .

  The volumetric hollow ratio of the hollow particles used in the present invention is preferably 25 to 97%, more preferably 30 to 95%, and most preferably 35 to 90%. When the volumetric hollow ratio of the hollow particles is less than 25%, the sensitivity improving effect of the entire receiving sheet may not be sufficiently exhibited. On the other hand, when the volumetric hollow ratio exceeds 97%, the coating strength of the intermediate layer is lowered, the intermediate layer is easily damaged, and the appearance may be deteriorated.

The volumetric hollow ratio of the hollow particles is 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, and the hollow particles in the dispersion It can be determined from the mass fraction and 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.
Moreover, about the average particle diameter and volume hollow rate of a hollow particle, the cross section can also be calculated | required from the cross-sectional photograph observation by a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

  In the intermediate layer of the present invention, the mass ratio of the hollow particles to the total solid content of the intermediate layer is preferably 20 to 90% by mass, more preferably 25 to 80% by mass. When the mass ratio of the hollow particles is less than 20% by mass, the effect of improving the sensitivity of the receiving sheet may be insufficient, and when the mass ratio of the hollow particles exceeds 90% by mass, the coating solution for the intermediate layer is applied. As a result, the coating surface strength of the intermediate layer may be lowered.

  As the hollow particles used in the intermediate layer of the present invention, two or more kinds of hollow particles having different average particle diameters, volumetric hollow ratios, or production methods can be used in combination. For example, a combination of two or more different already foamed hollow particles, a combination of two or more different microcapsule hollow particles, a combination of already foamed hollow particles and microcapsule hollow particles, and the like are particularly limited. Not. The intermediate layer is not limited to a single layer structure, and may have a laminated structure in which a plurality of coating layers are stacked, and the configuration is not particularly limited.

  The intermediate layer of the present invention contains hollow particles and an adhesive resin. The intermediate layer coating solution of the present invention is preferably an aqueous coating solution in view of the solvent resistance of the hollow particles. The adhesive resin used is not particularly limited. For example, hydrophilic polymer resins such as polyvinyl alcohol resins, cellulose resins and derivatives thereof, casein, and starch derivatives are film forming properties, heat resistance, and flexibility. Are preferably used. Also, emulsions of various resins such as (meth) acrylic acid ester resins, styrene-butadiene copolymer resins, urethane resins, polyester resins, ethylene-vinyl acetate copolymer resins are used as water-based resins with low viscosity and high solid content. . The adhesive resin used for the intermediate layer from the viewpoints of the coating strength, adhesiveness, and coatability of the intermediate layer can be a combination of the above hydrophilic polymer resin and emulsions of various resins.

  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.

  The thickness for the intermediate layer to exhibit desired performances such as heat insulation, cushioning properties and gloss improvement is preferably 20 to 90 μm, more preferably 25 to 85 μm. If the thickness of the intermediate layer is less than 20 μm, the heat insulating properties and cushioning properties are insufficient, and the effect of improving the sensitivity and image quality is insufficient. On the other hand, if the thickness exceeds 90 μm, the effects of heat insulation and cushioning are saturated, and further performance may not be obtained, which is economically disadvantageous.

(Receptive layer)
In the receiving sheet of the present invention, a receiving layer is provided directly or via a barrier layer or the like on the intermediate 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. Further, 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 above-described receiving layer. These additives may be mixed with the component for forming the receiving layer before coating, or may be coated on and / or under the receiving layer as a coating layer separate 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, it can be formed on a sheet-like support provided with an intermediate layer, a barrier layer, or the like by heating and curing as necessary after coating and drying.
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, when the solid content coating amount of the receiving layer is less than 1 g / m ² , the receiving layer may not completely cover the surface of the intermediate layer or the barrier layer, which may cause deterioration in image quality, There may be a fusing trouble that the receiving layer and the ink ribbon adhere to each other due to heating at. On the other hand, if the solid content coating amount exceeds 12 g / m ² , the coating layer strength of the receiving layer is insufficient, or the coating layer thickness becomes excessive, so that the heat insulation effect of the intermediate layer is not sufficiently exhibited, The image density may be lowered, and the coating effect is saturated, which is economically disadvantageous.

(Barrier layer)
In the present invention, a barrier layer is preferably provided between the intermediate layer and the receiving layer. In general, organic solvents such as toluene and methyl ethyl ketone are used as the solvent for the coating solution for the receiving layer. Therefore, the barrier layer is swelled by dissolution of the intermediate layer by penetration of the organic solvent, and the hollow particles are deformed and broken by dissolution. It is effective as a barrier to prevent this.

  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, silanol modified polyvinyl alcohol, acetoacetyl group Modified polyvinyl alcohol such as modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer, diisobutylene-maleic anhydride copolymer salt, styrene-maleic anhydride copolymer salt, styrene-acrylic acid copolymer salt, ethylene-acrylic Water-soluble resins such as acid copolymer salts, urea resins, urethane resins, melamine resins, and amide resins are used. 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 resins are preferably used. Moreover, said resin may be used individually or may be used in combination of 2 or more type.

  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. Examples of the swellable inorganic layered compound include synthetic mica such as fluorine phlogopite, potassium tetrasilicon mica, sodium tetrasilicon mica, sodium teniolite, lithium teniolite, or sodium hectorite, lithium hectorite, saponite, etc. Smectite is 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.

  As the swellable inorganic layered compound, those having an aspect ratio of 5 to 5,000 are preferably used, more preferably in the range of 100 to 5,000, and particularly preferably in the range of 500 to 5,000. . 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 the cross section of the barrier layer by photographic observation 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 lay the intermediate layer in parallel on the intermediate layer. When the average particle major axis exceeds 100 μm, the swellable inorganic layered compound protrudes from the barrier layer, resulting in irregularities on the surface of the barrier layer, and the smoothness of the surface of the receiving layer is lowered, resulting in deterioration of image quality. is there.

  In addition, in the barrier layer, in order to improve the texture of the concealability and whiteness, and the receiving sheet, calcium carbonate, titanium dioxide, zinc oxide, aluminum hydroxide, barium sulfate, silicon dioxide, aluminum oxide, White inorganic pigments such as 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. Aqueous coating liquid is used to prevent swelling and dissolution of hollow particles, such as ketone solvents such as methyl ethyl ketone, ester solvents such as ethyl acetate, lower alcohol solvents such as methyl alcohol and ethyl alcohol, and hydrocarbon solvents such as toluene and 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 coating amount of the solid content 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.

(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. This polymer 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 contain crosslinking agents, such as a polyisocyanate compound and an epoxy compound, in a back surface layer suitably.

  The back layer preferably contains an organic or inorganic filler as a friction coefficient adjusting agent. 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.

  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, anionic, nonionic, and cationic conductive polymer compounds are used. Among them, cationic conductive polymer compounds (for example, polyethyleneimine, acrylic polymers containing cationic monomers, cationic polymers) Modified acrylamide polymer, cationic starch, etc.) are preferably 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 , scratch resistance when the receiving sheet is rubbed may not be sufficiently exhibited, and poor running properties of the receiving sheet may occur. is there. 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. By this undercoat layer, even if the intermediate layer coating liquid is applied onto the support, the intermediate layer coating liquid does not penetrate into the support, and the intermediate layer is formed to a desired thickness. be able to. Examples of the polymer resin used for the undercoat layer include acrylic resins, polyurethane resins, polyester resins, polyolefin resins and modified resins thereof.

  The thickness of the entire receiving sheet is preferably 100 to 300 μm. When the thickness is less than 100 μm, the mechanical strength is insufficient, and the receiving sheet has insufficient rigidity, and the curling of the receiving sheet that occurs during printing may not be sufficiently prevented. In addition, if the thickness exceeds 300 μm, the number of receiving sheets that can be accommodated in the printer is reduced, or if the predetermined number of sheets is to be accommodated, the capacity of the receiving sheet accommodating portion needs to be increased. Problems such as making it difficult may occur.

In the method for producing a receiving sheet of the present invention, at least one surface of a sheet-like support is coated with an intermediate layer coating solution containing hollow particles and dried to form an intermediate layer, and / or the receiving layer is formed. A smoothing process is performed after the formation.
For example, the present invention includes at least the following steps (a) to (c).
(A) a step of providing an intermediate layer containing hollow particles on at least one surface of a sheet-like support mainly composed of cellulose pulp having a specific air permeability;
(B) providing a receiving layer on the intermediate layer;
(C) A step of performing a smoothing treatment through a receiving sheet through a nip portion of a pair of rolls composed of a heating roll and a press roll after forming the intermediate layer and / or after providing the receiving layer.

Further, after the step (a) of providing the intermediate layer, a step of providing a barrier layer on the intermediate layer and providing a receiving layer thereon, or a side of the sheet-like support on which the receiving layer is not provided, You may have the process of providing a layer.
Further, immediately after the smoothing treatment step (c), there may be provided a thickness restoration treatment step in which the receiving sheet is brought into contact with the heating roll and heated in a pressure-released state.

  The intermediate layer of the present invention comprises an intermediate layer coating solution containing at least hollow particles and the necessary components of an adhesive resin, a bar coater, a gravure coater, a comma coater, a blade coater, an air knife coater, a gate roll coater, a die coater, Using a known coater such as a curtain coater, a lip coater, and a slide bead coater, it can be coated on a sheet-like support and dried to form.

  When applying the intermediate layer, a molding surface may be used, or a metal plate, a metal drum, a plastic film, or the like having good dimensional stability and a highly smooth surface may be used. Moreover, in order to make it easy to peel the intermediate layer from the molding surface, if necessary, a higher fatty acid type release agent such as calcium stearate and zinc stearate, a polyethylene type release agent such as polyethylene emulsion, and wax on the molding surface. In addition, a release agent such as silicone may be applied.

  In addition, coating layers such as a barrier layer, a receptive layer, and a back layer 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 knife Using a known coater such as a coater, gate roll coater, die coater, curtain coater, lip coater, and slide bead coater, coat on a specified surface of the sheet-like support, dry, and as required It can be formed by heat curing.

  In the manufacturing method of the receiving sheet of this invention, it is preferable that a smoothing process process is included. The smoothing treatment is preferably performed by a calendering treatment in which unevenness on the surface of the receiving sheet is reduced by passing the receiving sheet between a pair of rolls consisting of a heating roll and a press roll with a certain clearance. At this time, heat and pressure can be applied between the pair of rolls. The smoothing treatment may be any of the intermediate layer surface, the barrier layer surface, the receiving layer surface, and the like. In particular, the surface of the intermediate layer and the surface of the receiving layer are preferably subjected to a smoothing treatment. Of course, the smoothing treatment can be performed on two or more surfaces.

  There are no particular limitations on the calendar apparatus used for the smoothing process and various processing conditions such as the nip pressure, the number of nips, and the heating roll surface temperature. A calendar device generally used in the paper industry, such as a calendar, gloss calendar, and machine calendar, can be used as appropriate.

  The nip pressure condition for the smoothing treatment is preferably 0.2 to 150 MPa, more preferably 0.3 to 100 MPa. The residence time of the receiving sheet at the nip is greatly affected by the hardness of the press roll, the linear pressure of the calendar, and the processing speed, but is preferably in the range of 5 to 500 milliseconds. As temperature conditions of a heating roll, the temperature range below the melting | fusing point of the binder contained in the coating layer which performs a smoothing process from room temperature is preferable, for example, 20-150 degreeC, More preferably, it is 30-120 degreeC. Moreover, as for the surface roughness of a heating roll, it is preferable that Ra value based on JISB0601 is 0.01-5 micrometers, More preferably, it is the range of 0.02-1 micrometer.

  In the method for producing a receiving sheet of the present invention, it is preferable that a thickness restoration process is further performed after the smoothing process. For example, as shown in the explanatory diagram of FIG. 1, the thickness restoring process is a process in which the receiving sheet is brought into contact with the heating roll and heated immediately after the smoothing process in a state where the pressure is released. When the receiving sheet is smoothed by passing through a nip in a pressurized state formed between a pair of rolls consisting of a heating roll and a press roll, the smoothness is improved, but the inside of the receiving sheet, particularly The intermediate layer is compressed to reduce the thickness. When this receiving sheet is brought into contact with a heating roll in a pressure-released state immediately after passing through the nip portion, the intermediate layer expands and the thickness increases, so that the density of the entire intermediate layer decreases, and the printing density of the receiving sheet decreases. Can be increased.

  The temperature of the heating roll in the thickness restoration treatment step may be the same as the heating roll condition in the smoothing treatment, preferably 20 to 150 ° C, more preferably 30 to 120 ° C. The contact time between the receiving sheet and the heating roll is preferably 0.5 seconds or longer, more preferably 1 second or longer.

  The present invention will be described in detail by the following examples, but the scope of the present invention is not limited thereto. In Examples, unless otherwise specified, “%” and “parts” all represent “% by mass” and “parts by mass”, and are solid amounts except for those relating to solvents.

Example 1
"Manufacture of paper substrate"
For 100 parts of bleached hardwood kraft pulp beaten to Canadian Standard Freeness 300CC at a water temperature of 20 ° C, 0.4 part of polyacrylamide (trade name: Polystron 117, manufactured by Arakawa Chemical Co., Ltd.), 1.0 part of Baking soda, 1.2 parts cationized starch (trade name: Cato-2, manufactured by NSC Japan), 1.0 part alkyl ketene dimer sizing agent (trade name: SPK903, manufactured by Arakawa Chemical Co., Ltd.), and 0 .3 parts of polyamide polyamine epichlorohydrin (trade name: WS-525, manufactured by Nippon PMC) was added, and a base paper having a basis weight of 180 g / m ² was produced from the obtained pulp slurry.
Further, a 5% size liquid prepared by dissolving carboxyl group-modified PVA and sodium chloride in water at a weight ratio of 2: 1 as a size press on this base paper has a coating amount of 1.5 g / m ² (after drying) After coating, it was dried and further calendered to obtain a sheet-like support. The air permeability based on JAPAN TAPPI No5-2 of the sheet-like support was 170 seconds.

"Formation of an intermediate layer"
An intermediate layer was formed by coating and drying an intermediate layer coating solution-1 having the following composition on one side of the sheet-like support so that the film thickness after drying was 51 μm.
Intermediate layer coating solution-1
45 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 10 parts Styrene-Pre-expanded hollow particles (average particle diameter 3.2 μm, volume hollow ratio 76%) made of a copolymer mainly composed of acrylonitrile and methacrylonitrile Butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 45 parts Water 250 parts

“Formation of barrier and receptor layers”
Furthermore, the barrier layer coating liquid-1 having the following composition was applied on the intermediate layer so as to have a solid content coating amount of 2 g / m ² and dried to form a barrier layer. The receiving layer coating solution-1 having the following composition was coated and dried so that the solid content coating amount was 5 g / m ² to form a receiving layer.
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 Co., Ltd.) 100 parts Silicone oil (trade name: KF393, manufactured by Shin-Etsu Chemical Co., Ltd.) 3 parts Polyisocyanate (trade name: Takenate D-140N, manufactured by Mitsui Takeda Chemical) 5 parts Toluene / Methyl ethyl ketone = 1/1 (mass ratio) mixture 400 parts

"Formation of back layer"
Next, on the surface of the sheet-like support opposite to the side on which the receiving layer is provided, the back layer coating solution-1 having the following composition is applied so that the solid coating amount after drying is 3 g / m ^2. The back layer was formed by coating and drying, and then aged at 50 ° C. for 48 hours to cure the receiving layer.
Back layer coating solution-1
Polyvinyl acetal resin (trade name: ESREC KX-1, manufactured by Sekisui Chemical Co., Ltd.) 40 parts Polyacrylate resin (trade name: Jurimer AT613, manufactured by Nippon Pure Chemicals) 20 parts nylon resin particles (trade name: MW330, Shinto Paint 10 parts zinc stearate (trade name: Z-7-30, manufactured by Chukyo Yushi) 10 parts cationic conductive resin (trade name: Chemistat 9800, manufactured by Sanyo Kasei) 20 parts water / isopropyl alcohol = 2/3 ( (Mass ratio) 400 parts of liquid mixture

"Formation of receiving sheet"
Further, calendering (roll surface temperature 78 ° C., nip pressure 2.5 MPa) is performed to smooth the surface of the receiving layer, and then immediately after releasing the pressure, the receiving layer surface is placed on a roll having a surface temperature of 78 ° C. for 2 seconds. The contact sheet was subjected to a thickness restoration process to obtain a receiving sheet.

Example 2
A receiving sheet was obtained in the same manner as in Example 1 except that “Manufacture of paper substrate” in Example 1 was changed as follows.
"Manufacture of paper substrate"
For 100 parts of bleached hardwood kraft pulp beaten to Canadian Standard Freeness 300CC at a water temperature of 20 ° C., 1.6 parts of polyacrylamide (trade name: Polystron 117, manufactured by Arakawa Chemical Co., Ltd.), 1.0 part of Baking soda, 1.2 parts cationized starch (trade name: Cato-2, manufactured by NSC Japan), 1.0 part alkyl ketene dimer sizing agent (trade name: SPK903, manufactured by Arakawa Chemical Co., Ltd.), and 0 .3 parts of polyamide polyamine epichlorohydrin (trade name: WS-525, manufactured by Nippon PMC) was added, and a base paper having a basis weight of 180 g / m ² was produced from the obtained pulp slurry.
Furthermore, as a size press on this base paper, a 5% size solution prepared by dissolving carboxyl group-modified PVA and sodium chloride in water at a weight ratio of 4: 1 has a coating amount of 2.0 g / m ² (after drying) After coating, it was dried and further calendered to obtain a sheet-like support. The air permeability of the sheet-like support was 350 seconds.

Example 3
In Example 1, a fine coated paper (trade name: Snowmat, basis weight 127.9 g / m ² , made by Oji Paper Co., Ltd.) was used as it was as the sheet-like support. A sheet was obtained. The air permeability of the fine coated paper was 850 seconds.

Example 4
A receiving sheet was obtained in the same manner as in Example 1 except that “Formation of intermediate layer” in Example 1 was changed as follows.
"Formation of an intermediate layer"
An intermediate layer was formed by coating and drying the intermediate layer coating liquid-2 having the following composition on one side of the sheet-like support so that the film thickness after drying was 55 μm.
Intermediate layer coating liquid-2
Microcapsule-shaped hollow particles made of a copolymer containing styrene and acrylic acid ester as main components (trade name: SX863A, manufactured by Nippon Synthetic Rubber, average particle size 0.4 μm, volume hollowness 30%) 70 parts polyvinyl alcohol (product) Name: PVA205, made by Kuraray) 10 parts Styrene-butadiene latex (trade name: PT1004, made by Nippon Zeon) 20 parts Water 250 parts

Example 5
A receiving sheet was obtained in the same manner as in Example 1 except that “Manufacture of paper substrate” in Example 1 was changed as follows.
"Manufacture of paper substrate"
For 100 parts of bleached hardwood kraft pulp beaten to Canadian Standard Freeness 300CC at a water temperature of 20 ° C., 1.6 parts of polyacrylamide (trade name: Polystron 117, manufactured by Arakawa Chemical Co., Ltd.), 1.0 part of Baking soda, 1.6 parts cationized starch (trade name: Cato-2, manufactured by NSC Japan), 1.6 parts alkyl ketene dimer sizing agent (trade name: SPK903, manufactured by Arakawa Chemical Co., Ltd.), and 2 0.0 parts of polyamide polyamine epichlorohydrin (trade name: WS-525, manufactured by Nippon PMC) was added, and a base paper having a basis weight of 180 g / m ² was produced from the obtained pulp slurry.
Further, a 5% size liquid prepared by dissolving carboxyl group-modified PVA and sodium chloride in water at a weight ratio of 2: 1 as a size press on this base paper has a coating amount of 1.5 g / m ² (after drying) After coating, it was dried and further calendered to obtain a sheet-like support. The air permeability of the sheet-like support was 200 seconds.

Comparative Example 1
In Example 1, a receiving sheet was obtained in the same manner as in Example 1 except that high-quality paper (trade name: OK high-quality paper, basis weight 157 g / m ² , manufactured by Oji Paper Co., Ltd.) was used as it was as the sheet-like support. It was. The fine paper had an air permeability of 50 seconds.

Comparative Example 2
In Example 1, a receiving sheet was obtained in the same manner as in Example 1 except that synthetic paper (trade name: YUPO FPG, basis weight 115.5 g / m ² , manufactured by YUPO Corporation) was used as it was as the sheet-like support. Obtained. The air permeability of the sheet-like support was 50000 seconds or more.

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.

[Air permeability]
The air permeability of the sheet-like support was measured with a Wangken air permeability tester based on JAPAN TAPPI No5-2. In addition, the sheet-like support used as a sample was prepared by leaving it to be conditioned for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH.

[Blister]
For each receiving sheet, the surface on the receiving layer side was subjected to visual sensory evaluation for the presence or absence of surface defects due to blistering during coating and drying, and the quality was determined according to the following criteria.
○: Good with no surface defects due to blisters.
X: There are surface defects due to blisters, and the appearance is poor, which is a practical problem.

(Print density)
For each receiving sheet, using a commercially available thermal transfer video printer (trade name: UP-DR100, manufactured by Sony Corporation), sublimation dyes of yellow, magenta, and cyan are combined with binders on a 6 μm thick polyester film. Using an ink ribbon provided with an ink layer, the surface of the ink layer of each color is brought into contact with the surface of the receiving sheet in sequence, and a predetermined image is thermally transferred to the receiving sheet by applying heat controlled stepwise with a thermal head. A halftone single-color image and a color-superimposed image of each color were printed.

  With respect to the recorded image for each applied energy transferred onto the receiving sheet of the printed matter, the reflection density was measured using a Macbeth reflection densitometer (trade name: RD-914, manufactured by Kollmorgen). The density of the high gradation portion corresponding to the 16th step from the lowest applied energy is shown in Table 1 as the print density.

[Image uniformity]
As the uniformity of the image of the printed matter, whether or not there is a print white spot in the gradation portion corresponding to the optical density (black) of 0.3 or the presence or absence of print unevenness in the recorded image according to the applied energy transferred onto the receiving sheet. Visual evaluation was performed.
Good evaluation results were indicated by ◯, print omissions or unevenness were slightly recognized, but those that were practically used were indicated by Δ, and those that were significantly unsuitable for practical use were indicated by ×.

[Thickness variation]
In the above Examples and Comparative Examples, a sample of a certain size (width 1100 mm × coating direction 300 mm) was cut out from a coated product having a width of 1100 mm provided with an intermediate layer. About this sample, the thickness of the coated product was measured at 16 locations at equal intervals in the width direction. From the obtained thickness data, thickness variation (R) was calculated by the following formula.
R (μm) = (maximum thickness) − (minimum thickness)
The thickness of the coated product was measured with a digital paper thickness gauge (trade name: D-105, manufactured by Toyo Seiki Co., Ltd.) in accordance with the method of JIS P 8118.

本発明の実施例１〜５においては、いずれも、印画面に印画抜け、印画ムラ、ブリスター等は発生しておらず、画像は良好であった。一方、比較例１，２においては、印画抜け、印画ムラ、またはブリスターが発生し、実施例と比較して劣るものであった。

In each of Examples 1 to 5 of the present invention, no omission of printing, uneven printing, blistering or the like occurred on the printing screen, and the image was good. On the other hand, in Comparative Examples 1 and 2, printing omission, printing unevenness, or blistering occurred, which was inferior to the examples.

  The receiving sheet of the present invention is suitable for a dye thermal transfer printer, has improved unevenness in density, white spots, blisters, etc., can be recorded at low cost, with high sensitivity and high image quality, and is an extremely excellent receiving sheet, It is excellent in practical use.

Schematic which shows the smoothing process of a receiving sheet of this invention, and a thickness restoration process process.

Claims (6)

  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 comprising cellulose pulp as a main component, the sheet-like support based on JAPAN TAPPI No. 5-2 is used. A thermal transfer receiving sheet characterized by having a temperament of 100 seconds or more and less than 1000 seconds.   The thermal transfer receiving sheet according to claim 1, wherein the hollow particles have an average particle diameter of 0.2 to 15 µm and a volumetric hollowness of 25 to 97%.   The thermal transfer receiving sheet according to claim 1, wherein the sheet-like support contains a wet strength enhancer of 0.1 to 5% by mass with respect to cellulose pulp solid content.   In the method for producing 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 mainly composed of cellulose pulp, the JAPAN TAPPI No5-2 of the sheet-like support is used. The air permeability based on the above is 100 seconds or more and less than 1000 seconds, and the intermediate layer is formed by applying and drying the intermediate layer coating liquid containing hollow particles on at least one surface of the sheet-like support. And / or smoothing treatment after the image receiving layer is formed.   The manufacturing method of the thermal transfer receiving sheet of Claim 4 in which the said sheet-like support body contains 0.1-5 mass% wet strength enhancer with respect to cellulose pulp solid content. 6. The method for producing a thermal transfer receiving sheet according to claim 4, wherein a thickness restoration process is further performed after the smoothing process.

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