JP2006341588A - Method for manufacture of thermal transfer receiving sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a receiving sheet capable of manufacturing at a low cost a receiving sheet which is very high image quality since thick and thin irregularity, dropping out or the like are improved in a receiving sheet suitable for a dye thermal transfer printer and to which an intermediate layer containing a hollow particle is provided. <P>SOLUTION: In a method for manufacturing a thermal transfer receiving sheet which successively forms an intermediate layer having a hollow particle and an image receiving layer on at least one surface of a sheet like supporter, after forming the intermediate layer and/or after forming the image receiving layer on at least one surface of the sheet like supporter, a surface temperature of the intermediate layer or the image receiving layer is adjusted at a range of 30-130°C, the method for manufacturing the thermal transfer receiving sheet carries out a smoothing process through a nip part of a pair of rolls comprising a metallic heating roll and an elastic roll by adjusting a surface temperature of the intermediate layer or the image receiving layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention superimposes on a thermal transfer sheet (also referred to as “ink ribbon”) and thermally transfers a dye on the ink ribbon with a thermal head to form an image (hereinafter simply referred to as “receptor sheet”). )). More specifically, the present invention is particularly suitable for a dye thermal transfer printer, and relates to a method for producing a receiving sheet having an intermediate layer containing hollow particles between a sheet-like support and an image receiving layer.

  The dye thermal transfer printer superimposes a dye layer containing a dye on an ink ribbon and an image receiving layer (hereinafter simply referred to as a “receiving layer”) containing a dye-stainable resin on a receiving sheet, 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 the supplied heat. The ink ribbon sequentially has dye layer regions 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 development of digital image processing technology using computers has dramatically improved the quality of recorded images and the market for dye thermal transfer systems. In addition, with the improvement of the thermal head temperature control technology, there is an increasing demand for high speed and high sensitivity of the printing system. Therefore, how to efficiently use the amount of heat generated by a heating device such as a thermal head for image formation is an important technical issue. In addition, there is a demand for printer price reduction and structure simplification, and lowering of the printing pressure by a thermal head and extending the life of the head are also technical issues. Currently, printers that can print one A6 size within 30 seconds are also on sale, and it is expected that there will be further demands for higher printing speeds in the future.

  In general, in order to efficiently form an image with high image quality and high density, a receiving sheet provided with a receiving layer mainly composed of a dye-dyeable resin on a support is used. When a normal film is used, the smoothness is excellent, but the heat from the thermal head escapes to the base material, resulting in insufficient recording sensitivity, and the film does not have sufficient cushioning properties. Inadequate adhesion results 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 (see, for example, Japanese Patent Laid-Open No. 61-197282 (Patent Document 1)). A support or the like in which a biaxially stretched film (synthetic paper) including a void (void) structure as a main component and a thermoplastic resin such as a polyolefin resin is bonded to a core material layer such as paper has been proposed (for example, (See JP-A 62-198497 (Patent Document 2).) Receptor sheets using these supports are excellent in heat insulation and smoothness, but have drawbacks such as no paper-like texture and high cost.

  In addition, when paper is used as the support for the receiving sheet, the recording sensitivity is insufficient as in the case of the film, and the cushioning property is slightly better than that of the film, but uneven adhesion between the ink ribbon and the receiving layer 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 a paper support and a receiving layer in order to improve transfer density and the like (for example, JP-A-63-87286). (See Patent Document 3) and Japanese Patent Laid-Open No. 1-27996 (Patent Document 4). The sensitivity of this receiving sheet is improved by the effect of improving the heat insulating property and cushioning property of the hollow particle-containing layer, but there is a tendency that the receiving sheet surface is uneven due to the influence of the hollow particles.

  Regarding the improvement of the unevenness on the surface of the receiving sheet, a receiving sheet having a specific surface roughness, glossiness, etc. has been proposed by defining the average particle diameter and hollowness ratio of the hollow particles used in the intermediate layer (for example, special features (See Kaihei 9-99651 (Patent Document 5) and JP-A-2001-39043 (Patent Document 6).) In addition, in a receiving sheet formed by forming a resin layer including a bubble layer and a receiving layer on a base sheet, a method for smoothing the bubble layer and / or the receiving layer has been proposed (for example, Japanese Patent Laid-Open No. 6-210968 (Patent Document 7).)

  In order to obtain good image quality and image uniformity with a conventional high-speed and low printing pressure printer using conventional smoothing processing technology, it is necessary to improve the smoothness of the surface of the receiving layer. Specifically, in a general calendar apparatus, it is necessary to increase the surface pressure during the smoothing process or to increase the time for nip processing with a roll (hereinafter referred to as “nip time”). However, because the former has a high surface pressure, the thickness of the intermediate layer containing the hollow particles is reduced, the printing density is lowered, and the image uniformity is lowered. In the latter, the smoothing processing speed is not increased, The result was an increase in manufacturing costs.

JP 61-197282 A (first page) JP-A-62-198497 (first page) JP-A-63-87286 (page 1-2) Japanese Patent Laid-Open No. 1-27996 (page 1-3) JP-A-9-99651 (page 2-3) JP 2001-39043 A (page 2-3) JP-A-6-210968 (page 2-4)

  The present invention has been made in view of the above circumstances, and has solved the above-mentioned problems of the conventional method for producing a receiving sheet, and is particularly suitable for a dye thermal transfer printer and provided with an intermediate layer containing hollow particles. An object of the present invention is to provide a method for producing a receiving sheet, in which unevenness in light and shade, white spots, etc. are improved and an extremely high quality receiving sheet can be produced at low cost.

The present invention includes the following inventions.
(1) In the method for producing a thermal transfer receiving sheet in which an intermediate layer having hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support, after forming the intermediate layer on at least one surface of the sheet-like support and After the image receiving layer is formed, the surface temperature of the intermediate layer or the image receiving layer is adjusted to a range of 30 to 100 ° C., and smoothing is performed through the nip portion of a pair of rolls including a metal heating roll and an elastic roll. A method for producing a thermal transfer receiving sheet.
(2) The hollow particles have an average particle diameter of 0.2 to 30 μm and a volume hollowness of 25 to 95%, and an applied pressure of 0.05 MPa using a microtopograph on the surface of the image receiving layer. The method for producing a thermal transfer receiving sheet according to (1), wherein the static printing smoothness (Rp value) measured in step (1) is smoothed so as to be 0 to 4.0 μm.
(3) The method for producing a thermal transfer receiving sheet according to (1) or (2), wherein the surface temperature is adjusted by contacting the surface of the metal heating roll before passing through the nip portion.
(4) The method for producing a thermal transfer receiving sheet according to (1) or (2), wherein the surface temperature is adjusted using a preheating roll.
(5) After the smoothing process, the intermediate layer or the image receiving layer is brought into contact with a heating roll in a pressure-released state to perform a thickness restoration process (1) to (4) The manufacturing method of the thermal transfer receiving sheet of any one of these.
(6) The method for producing a thermal transfer receiving sheet according to any one of (1) to (5), wherein the image receiving layer contains a vinyl chloride resin as a main component.
(7) The method for producing a thermal transfer receiving sheet according to (6), wherein the vinyl chloride resin is a vinyl chloride resin having active hydrogen.

  The receiving sheet manufacturing method of the present invention is suitable for a dye thermal transfer printer, and is capable of producing a receiving sheet with extremely high image quality at low cost and at high speed, which is improved in uneven density and white spots.

Next, the present invention will be described in more detail with reference to preferred embodiments.
In order to obtain high-sensitivity and high-quality images during printing, the receiving sheet is sufficiently in close contact with the ink ribbon during printing, and further deforms following the shape of the thermal head to efficiently heat the thermal head. It is necessary to use it for image formation. Accordingly, the receiving sheet is required to have a high smoothness on the surface of the receiving layer under an applied pressure during printing.

  In the receiving sheet of the present invention, an intermediate layer having hollow particles and a receiving layer are sequentially formed on at least one surface of a sheet-like support. In producing such a receiving sheet, the smoothness of the receiving layer surface is improved. In order to improve, after the formation of the intermediate layer and / or after the formation of the receiving layer, a smoothing treatment by a calendar that performs nip treatment with a metal heating roll and an elastic roll is effective, and a surface layer (intermediate layer or It has been found that smoothing proceeds more by adjusting the surface temperature of the receiving layer to a range of 30 to 130 ° C. The surface temperature of the surface layer is more preferably in the range of 35 to 120 ° C, and further preferably in the range of 40 to 115 ° C.

When the surface temperature of the surface layer immediately before the nip treatment is less than 30 ° C., there is almost no effect on the smoothing treatment, and when it exceeds 130 ° C., the release layer becomes heavy when the receiving layer is released from the metal heating roll, and the separation occurs. Appearance defects such as lines are produced.
In the present invention, the nip treatment is performed after the intermediate layer is formed or after the receptor layer is formed, and may be performed both after the intermediate layer is formed and after the receptor layer is formed, if necessary, preferably after the receptor layer is formed. .

  For example, when the receiving layer is formed, when the calender is released from the intermediate layer due to heat during nip processing, plasticization of the receiving layer resin, deformation of the receiving sheet surface due to pressure, transfer of the metal heated roll surface shape, nip pressure It is thought that the receiving sheet surface is smoothed by the elasticity of the receiving layer surface that is generated. However, by setting the receiving layer surface temperature immediately before the nip to 30 to 130 ° C., the plasticization of the resin during the nip process is further improved. In order to proceed uniformly in a short time, it is considered that smoothness is more efficiently imparted.

In order to adjust the surface temperature immediately before the nip processing to a range of 30 to 130 ° C., for example, as shown in FIG. Shows a method of passing the metal in contact with the surface of the metal heating roll. For example, the surface temperature of the receiving sheet substrate immediately before the nip treatment can be adjusted to 30 to 130 ° C. by appropriately adjusting the contact area, the heating time, and the like.
In view of the workability of the smoothing process, the heat treatment time is preferably in the range of 50 to 2000 milliseconds. The surface temperature of the receiving sheet substrate immediately before the nip treatment can be measured using, for example, a non-contact type radiation thermometer (trade name: IT-550F, manufactured by Horiba, Ltd.).

  In addition, a general heating device (also referred to as a preheating device) can be used. Specifically, means such as a warming roll (also referred to as a preheating roll), a warm air generator such as an infrared heater or an oven can be used as appropriate, and a method using a preheating roll as shown in FIG. It is efficient and is preferably performed. For example, as a temperature condition of a preheating roll, 30-135 degreeC is preferable, More preferably, it is 35-125 degreeC, More preferably, it is 40-120 degreeC.

A preferable nip pressure condition for the smoothing treatment is preferably 0.2 to 150 MPa, more preferably 0.3 to 100 MPa, and particularly preferably 2 to 50 MPa. The nip time is largely affected by the hardness of the elastic roll, the nip pressure, etc., but is preferably in the range of 5 to 500 milliseconds. The temperature condition of the metal heating roll is preferably 30 to 130 ° C., more preferably 35 to 120 ° C., as the temperature range below the melting point of the adhesive resin contained in the coating layer that performs the smoothing treatment from the room temperature condition. More preferably, it is 40-115 degreeC.
Moreover, as for the surface roughness of a metal heating roll, it is preferable that Ra value based on JISB0601 is 0.01-1.0 micrometer, More preferably, it is the range of 0.02-1.0 micrometer. If the Ra value is less than 0.01 μm, the glossiness of the resulting product becomes too high and gloss unevenness may occur. On the other hand, when the Ra value exceeds 1.0 μm, the print smoothness Rp value of the obtained product increases, and the image uniformity may be poor.

  In the present invention, the 20 ° glossiness (glossiness at an incident light angle of 20 °) measured according to JIS Z 8741 on the surface of the receiving layer is preferably 80% or less, more preferably 30 to 70%. It is. The cushioning property is improved by forming the intermediate layer containing the hollow particles, but if the glossiness exceeds 80%, the surface of the receptor layer may be conspicuous. For example, when receiving sheets are stacked and stored, the back surface of the receiving sheet comes into contact with the surface of the receiving layer, and the receiving layer surface is partially scratched, resulting in uneven gloss and reducing the product value in appearance. is there. When the glossiness of the receiving layer surface is less than 30%, the image glossiness of an image printed by a thermal transfer printer may be inferior.

  In the present invention, it is preferable that a thickness restoration process is further performed after the smoothing process. The thickness restoration process is a step of heating the receiving sheet in contact with the metal heating roll in a pressure-released state (see, for example, FIG. 3). When the receiving sheet is smoothed through a nip portion in a pressurized state formed between a pair of rolls composed of a metal heating roll and an elastic roll, the surface smoothness is improved, but the inside of the receiving sheet, particularly the intermediate layer Is compressed to reduce the thickness. Immediately after passing through the nip portion, when the receiving sheet is brought into contact with a heating roll in a pressure-released state, the intermediate layer is appropriately expanded and the thickness is increased, so that the density of the entire intermediate layer is reduced. Image quality and print density 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, and is preferably 30 to 130 ° C. The contact time between the receiving sheet and the metal heating roll is preferably 0.5 seconds or more, more preferably 1 second or more.

  In the present invention, the smoothing treatment conditions when the smoothing treatment is performed on the coated surface of the receiving layer are greatly influenced by the thermal properties (particularly the glass transition temperature of the resin) of the dye-dyeing resin of the receiving layer. When the glass transition temperature of the resin is high, the resin is less likely to be thermally deformed and smooth. Prior to the smoothing step as in the present application, the plasticization of the resin proceeds in a short time by adjusting the surface layer temperature of the receiving sheet to a predetermined range in advance, and the smoothing process can be performed efficiently. .

  The smoothness of the receiving sheet, that is, the contact ratio between the receiving sheet and the thermal head is important for the printing density and the printing image quality of the receiving sheet. For the smoothness of the receiving layer surface, a microtopograph is used and the applied pressure is 0. It was found that a high-sensitivity, high-quality image can be obtained by adjusting the static printing smoothness (Rp value) of the receiving layer surface as measured at .05 MPa to 0 to 4.0 μm. When the Rp value exceeds 4.0 μm, the smoothness of the receiving sheet surface is insufficient, and the printing density and printing image quality of the receiving sheet are inferior. The Rp value is preferably 0 to 3.0 μm. The printing smoothness (Rp value) is a physical quantity measured in proportion to the average depth of the indentation on the sample surface that is pressure-bonded to a reference plane (prism). No. 3 (1978), The Japan Printing Society 60th Spring Research Presentation (1978), etc.

The layer structure of the receiving sheet of the present invention has at least a sheet-like support, an intermediate layer, and a receiving layer, and these layers will be described in detail below.
(Sheet support)
Examples of the sheet-like support used in the present invention include (1) high-quality paper (acidic paper, neutral paper, etc.), medium-quality paper, coated paper, art paper, glassine paper, cast coated paper, at least one of polyolefin Cellulose pulp such as laminated paper, synthetic resin-impregnated paper, emulsion-impregnated paper, synthetic rubber latex-impregnated paper, synthetic resin-incorporated paper, foamed paper containing thermally expandable particles, and paperboard with a thermoplastic resin layer such as resin Papers as the main component, or (2) Polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, plastic films mainly composed of thermoplastic resins such as polyamide, polyvinyl chloride, polystyrene, and these resins A molten mixture containing an incompatible resin or inorganic pigment is extruded from an extruder and further stretched to empty. Porous stretched film (for example, synthetic paper, porous polyester film) having a single layer structure or a multilayer structure in which the film is generated, or these films, or a laminate of these films and other films or papers A composite film or the like that has been used is appropriately used.

  Among the above-mentioned various sheet-like supports, papers mainly composed of cellulose pulp have low heat shrinkability, good heat insulation, good texture as receiving paper, and are inexpensive. Are preferably used. The sheet-like support of the present invention may have a structure in which a first substrate layer on which a receiving layer is formed, an adhesive layer, a release agent layer, and a second substrate layer are sequentially laminated. Of course, a sheet-like support having a structure of a sticker or a seal type can also be used.

  The sheet-like support used in the present invention preferably has a thickness of 100 to 300 μm. Incidentally, if the thickness is less than 100 μm, the mechanical strength is insufficient, the rigidity of the receiving sheet obtained therefrom is small, the repulsive force against deformation is insufficient, and the curling of the receiving sheet generated during printing is sufficiently prevented. It may not be possible to prevent. 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.

(Middle layer)
In the present invention, an intermediate layer is formed on at least one side of the sheet-like support. Since the intermediate layer has a porous structure mainly composed of an adhesive resin and hollow particles and has a high cushioning property, a highly sensitive receiving sheet can be obtained even when paper is used as the sheet-like support. By containing hollow particles in the intermediate layer, the receiving sheet is given a suitable degree of deformation freedom, and the followability and adhesion of the receiving sheet to the printer head shape and ink ribbon shape are improved. The thermal efficiency of the printer head can be improved, the print density can be increased, and the image quality can be improved. Also, in the high energy application operation of the high-speed printer, it is possible to prevent printing defects due to ribbon wrinkles generated on the ink ribbon at the same time.

  By including hollow particles in the intermediate layer, the heat insulating property of the receiving sheet is improved, thereby improving the thermal efficiency of the thermal head with respect to the receiving layer, thereby increasing the print density and improving the image quality. In addition, even if the receiving sheet receives high pressure from the thermal head of the printer and the conveying roll, this stress can be absorbed inside the receiving sheet. Therefore, formation of spike marks and dents on the receiving sheet marking screen by the conveying roll. Etc. are improved.

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 portions surrounded by the shell, and the method for producing the hollow particles is exceptional. There is no limitation, but it can be selected from those manufactured as shown in (a) and (b) below.
(A) Expanded hollow particles produced by thermally expanding a thermoplastic polymer material containing a thermally expandable substance (hereinafter sometimes referred to as “pre-expanded 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. Microcapsule-like hollow particles obtained by the above process.

  Also, as hollow particles, particles (expandable particles) made of a thermoplastic material containing a thermally expansible material are used in an unfoamed state, and foamed by the heat in the manufacturing process of the receiving sheet, for example, the drying process. It is also conceivable to form foamed hollow particles. However, as described above, if a thermoplastic material containing a thermally expandable material is foamed by heating during the manufacturing process of the receiving sheet, it is difficult to foam to a uniform particle size, and the particle size after thermal expansion is strictly limited. Since it cannot be managed, the surface of the intermediate layer becomes a surface with large irregularities, and the smoothness may be inferior. Since the receiving sheet having the intermediate layer as described above also has large irregularities on the surface of the receiving layer, the uniformity of the heat-transferred image may be lowered and the image quality may be inferior. Therefore, in the present invention, pre-expanded hollow particles produced by thermally expanding particles made of a thermoplastic material containing a thermally expandable material in advance are preferably used.

  The foamed hollow particles produced by thermally expanding a thermally expandable material-containing thermoplastic material are, for example, low-volatile materials such as n-butane, i-butane, pentane, and / or neopentane as a thermally expandable core material. A boiling point hydrocarbon is encapsulated in a thermoplastic material, and a homopolymer or copolymer such as vinylidene chloride, vinyl chloride, acrylonitrile, methacrylonitrile, styrene, (meth) acrylic acid ester or the like is used as the thermoplastic material in a capsule shell ( The particles obtained as a (wall) material are subjected to a treatment such as heating in advance, so that they are thermally expanded to a predetermined particle diameter to obtain pre-expanded hollow particles.

  Further, the foamed hollow particles produced by thermally expanding the thermoplastic material-containing thermoplastic material as described above generally have a small specific gravity. Therefore, for the purpose of further improving the handling workability and dispersibility, Foamed composite hollow particles in which an inorganic powder such as calcium, talc, titanium dioxide or the like is adhered to the surface of the already foamed hollow particles by heat fusion and the surface is coated with the inorganic powder can also be used in the present invention.

  The microcapsule-like hollow particles used in the present invention contain a polymer material, for example, a styrene-acrylic copolymer or a hard resin such as a melamine resin as a shell, and a volatile liquid such as water in the core. The microcapsule is dried, and water is volatilized and escaped to form a hollow core part. 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.

  The average particle diameter of the hollow particles used in the present invention is 0.2 to 30 μm, preferably 0.5 to 10 μm, more preferably 0.8 to 8 μm. When the average particle diameter of the hollow particles is less than 0.2 μm, the volumetric hollow ratio of the obtained hollow particles is low, so that the heat insulation and cushioning properties are generally low, so that the sensitivity and the image quality improvement effect are sufficiently obtained. There may not be. On the other hand, when the average particle diameter exceeds 30 μm, the smoothness of the surface of the obtained intermediate layer is lowered, the unevenness of the surface of the receiving sheet is increased, the uniformity of the thermal transfer image is insufficient, and the image quality may be inferior.

  Further, the maximum particle size of the hollow particles used in the present invention is preferably 100 μm or less, more preferably 50 μm or less, and further preferably 20 μm or less. If the maximum particle diameter of the hollow particles exceeds 100 μm, the thermal transfer image may cause unevenness in the density of prints and white spots due to coarse particles, resulting in poor image quality. In order to prevent the hollow particles from containing coarse particles having a maximum particle diameter exceeding 100 μm, in the production of hollow particles generally exhibiting a normal distribution state, the set value of the average particle diameter is adjusted. 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. In addition, the particle diameter of the hollow particles described in the present specification can be measured using a general particle size measuring device, and a laser diffraction type particle size distribution measuring instrument (trade name: SALD2000, manufactured by Shimadzu Corporation) is used. It is a measured value.

  The volume hollowness of the hollow particles used in the present invention is preferably 25 to 95%, more preferably 30 to 95%. When the volumetric hollow ratio is less than 25%, the image quality may deteriorate. On the other hand, if the volume hollowness exceeds 95%, the strength of the coating layer is inferior, and the hollow particles may be destroyed during coating and drying, leading to a decrease in surface smoothness.

Note that the volumetric hollow ratio of the hollow particles indicates the ratio of the volume of the hollow portion to the total 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 average particle diameter and volumetric hollow ratio of the hollow particles can be determined by observing a cross-section of the hollow particles by observing a cross-sectional photograph with a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

  The blending amount of the hollow particles in the intermediate layer is preferably in the range of 30 to 75% by mass, more preferably in the range of 35 to 70% by mass in terms of the ratio of the mass of the hollow particles to the total solid mass of the entire intermediate layer. When the mass ratio of the hollow particles to the total solid mass of the entire intermediate layer is less than 30% by mass, 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. Moreover, when the mass ratio of the hollow particles exceeds 75% by mass, the coating property of the resulting intermediate layer paint is lowered, and the coating film strength may be insufficient, and the desired effect may not be obtained. is there.

  In order for the intermediate layer to exhibit desired performance such as heat insulation and cushioning, the thickness of the intermediate layer is preferably 20 to 90 μm, more preferably 25 to 85 μm. If the film thickness of the intermediate layer is less than 20 μm, the heat insulation and cushioning properties are insufficient, and the sensitivity and image quality improvement effect may be insufficient. On the other hand, if the film thickness exceeds 90 μm, the effects of heat insulation and cushioning are saturated, and not only higher performance can be obtained, but also it may be economically disadvantageous.

  The intermediate layer of the present invention contains hollow particles and an adhesive resin. The intermediate layer coating material of the present invention is preferably an aqueous coating material in consideration of the solvent resistance of the hollow particles. Accordingly, the adhesive resin can be either water-based or organic solvent-based, but is more preferably an aqueous resin. 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. 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 are used as low-viscosity and high-solids aqueous resins. The The adhesive resin used for the intermediate layer is preferably a combination of the hydrophilic polymer resin and an emulsion of various resins from the viewpoints of coating strength, adhesiveness, and coatability of the intermediate layer.

  In the intermediate layer, various additives, for example, an antistatic agent, an inorganic pigment, an organic pigment, a resin crosslinking agent, an antifoaming agent, a dispersing agent, a colored dye, a release agent, a lubricant, etc. Two or more kinds may be appropriately selected and used.

(Barrier layer)
In the present invention, if necessary, a barrier layer may be provided on the intermediate layer, and the receptor layer is provided on this barrier layer. In this barrier layer, the solvent of the coating material for the receiving layer is generally an organic solvent such as toluene and methyl ethyl ketone, and is effective as a barrier for preventing the hollow particles in the intermediate layer from swelling and dissolving due to penetration of the organic solvent. In addition, since the surface of the intermediate layer has irregularities due to the hollow particles of the intermediate layer, the receiving layer provided thereon may also have irregularities on the surface, and the resulting image has many white spots and uneven shading due to the irregularities. In some cases, problems arise in image uniformity and resolution. In order to improve this problem, it is effective to improve the image quality to provide a barrier layer containing an adhesive resin having flexibility and elasticity.

  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, 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. A 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.

  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 inorganic pigments, 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. As the inorganic pigment, a swellable inorganic layered compound is preferably used, and an excellent effect is obtained not only in preventing penetration of a coating solvent but also in preventing blurring of a thermal transfer dyed image. 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.).

The barrier layer of the present invention is preferably formed using an aqueous coating solution. 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 that an organic solvent such as a solvent, DMF, cellosolve and the like having a high boiling point and a high polarity is not excessively contained. The solid content coating amount of the barrier layer is preferably in the range of 0.5 to 10 g / m ² , more preferably in the range of 1 to 8 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 intermediate layer surface, 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 10 g / m ² , the coating effect is saturated and not only uneconomical, but also the heat insulation effect of the intermediate layer due to the excessive thickness of the barrier layer The cushioning property is not 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 intermediate layer (via a barrier layer if necessary). 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 transferred from the ink ribbon and 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).

  The glass transition temperature of the dye-dyeing resin used in the present invention is preferably 40 to 110 ° C, more preferably 50 to 100 ° C. When the glass transition temperature is less than 40 ° C., the releasability between the receiving layer and the ink ribbon is insufficient during printing, and when the glass transition temperature exceeds 110 ° C., the dyeing property is insufficient. The print density may be low. The glass transition temperature of the dye-dyeing resin is a value measured using an inspection scanning calorimeter (trade name: SSC5200, manufactured by Seiko Denshi Kogyo Co., Ltd.) according to the method defined in JIS K7121.

  Among these dye-dyeing resins, polyvinyl chloride resins such as polyvinyl chloride resin and vinyl chloride-vinyl acetate copolymer resin have high printing density and good adhesion of the protective layer of the ink ribbon to the printed image. Yes, it is preferably used as a resin for the receiving layer. In the vinyl chloride resin, the unit derived from vinyl chloride in the resin component is preferably 70% by mass or more.

  In addition, a vinyl chloride resin having an active hydrogen in which a part of these vinyl chloride resin components is substituted with vinyl alcohol or hydroxyalkyl acrylate to introduce a hydroxyl group can be used in combination with a crosslinking agent such as a polyvalent isocyanate compound. It is possible to improve releasability and heat resistance, and it is more preferably used.

  In addition, in order to prevent the receiving layer and the ink ribbon from fusing 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 blended as an agent.

  As the cross-linking agent, a cross-linking agent such as a polyvalent isocyanate compound, an epoxy compound, or an organometallic compound is generally used, and the dye-dyeable resin or the like can be cross-linked. In the receiving layer of the present invention, it is preferable to use a polyvalent isocyanate compound having good reactivity. The compounding amount of the polyvalent isocyanate compound is such that the number of functional groups capable of reacting with the isocyanate group is about 0.1 to 50, more preferably 0.15 to 10, with respect to the functional group 1 of the polyvalent isocyanate compound. It is preferable to do.

  Specific examples of the polyvalent isocyanate compound include various diisocyanate compounds, triisocyanate compounds, and polyisocyanate compounds. Specifically, tolylene diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, diphenylmethane diisocyanate, and tolidine diisocyanate. , Isophorone diisocyanate, norbornane diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, hydrogenated diphenylmethane diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, triphenylmethane triisocyanate, tetramethylxylene diisocyanate, and modified products and derivatives thereof. Can be mentioned. In general, from the viewpoint of stability, safety, and handling properties, various diisocyanate compounds are modified or prepolymerized into so-called adducts, biurets, isocyanurates, polyfunctional prepolymers, and other multimers. Used.

  Moreover, you may add 1 or more types, such as fluorescent dye, a plasticizer, antioxidant, a pigment, a filler, an ultraviolet absorber, antistatic agent, etc. in said receiving layer as needed. 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 solid content coating amount of the receiving layer is preferably 1 to 12 g / m ² , more preferably ² 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 barrier layer surface, which may cause deterioration in image quality or heating of the thermal head. There may be a fusing problem that the ink ribbon and the ink ribbon are bonded. On the other hand, when the solid content coating amount exceeds 12 g / m ² , not only is the effect saturated and uneconomical, but also the coating strength of the receiving layer is insufficient and the coating thickness becomes excessive. Therefore, the heat insulating effect of the sheet-like support and 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 layer may be provided on the back side of the sheet-like support (the side opposite to the side on which the receiving layer is provided). The back layer is mainly composed of a resin effective as an adhesive, and may contain a crosslinking agent, a conductive agent, an anti-fusing agent, an inorganic and / or organic pigment, and the like.

  For the back layer of the present invention, 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 sheet-like support, print transportability of the receiving sheet, preventing scratches on the receiving layer surface, and preventing the dye from transferring 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.

  In the back layer of the present invention, a cross-linking agent such as a polyisocyanate compound or an epoxy compound may be appropriately added to the back layer coating material in order to improve the adhesion between the sheet-like support and the back layer. As a compounding ratio, generally about 1-30 mass% is preferable with respect to the back layer total solid content.

  A conductive agent such as a conductive polymer or a conductive inorganic pigment may be added to the back layer of the present invention in order to improve print transportability and prevent static electricity. Examples of the conductive polymer include cationic, anionic and nonionic conductive polymer compounds. Examples of the cationic polymer compound include polyethyleneimine, acrylic polymers containing cationic monomers, and cation-modified acrylamide polymers. And cationic starch. Examples of the anionic polymer compound include polyacrylate, polystyrene sulfonate, and styrene-maleic acid copolymer. In general, the blending ratio of the conductive agent is preferably about 5 to 50% by mass with respect to the total solid content of the back surface layer.

  Examples of conductive inorganic pigments include compound semiconductor pigments such as oxides and / or sulfides, and inorganic pigments coated with the compound semiconductor pigments. Examples of the compound semiconductor include copper (I) oxide, zinc oxide, zinc sulfide, and silicon carbide. Examples of inorganic pigments coated with a compound semiconductor include titanium oxide and potassium titanate coated with semiconductor tin oxide, and acicular and spherical conductive inorganic pigments are commercially available.

  If necessary, an organic or inorganic filler can be blended in the back layer of the present invention 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. For example, in the case of a nylon filler, the average particle size is preferably about 1 to 25 μm, and the blending amount is preferably about 2 to 30% by mass with respect to the total solid content of the back surface layer, although it depends on the particle size.

  The back layer may contain an anti-fusing agent such as a lubricant and a release agent as necessary. Examples of the anti-fusing agent include non-modified and modified silicone oils, silicone block copolymers, silicone compounds such as silicone rubber, phosphate ester compounds, fatty acid ester compounds, fluorine compounds, and the like. 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, coating defects occur, and the surface electrical resistance value is May go up. 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 sheet-like 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. Waviness may occur, and the texture and printability may be adversely affected. Therefore, in such a case, 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. The 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 of the undercoat layer is saturated and uneconomical. In addition, the texture of the receiving sheet as paper may be lost.

  In the present invention, the intermediate layer, the barrier layer, the receiving layer, the back layer, and the other coating layers are formed according to a conventional method, and each of them prepares a coating solution containing necessary components, and a bar coater, a gravure coater, a comma Using a known coater such as a coater, a blade coater, an air knife coater, a gate roll coater, a die coater, a curtain coater, a lip coater, and a slide bead coater, coating on a predetermined surface of a sheet-like support, After drying, it can be heated and cured as necessary.

  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” indicate “% by mass” and “parts by mass”, and are solid amounts except for those relating to solvents.

Example 1
"Formation of back layer"
As the sheet-like support, art paper having a thickness of 150 μm (trade name: OK Kanto N, 174.4 g / m ² , manufactured by Oji Paper Co., Ltd.) is used, and the coating solution for back layer 1 having the following composition is applied on one side thereof. The back layer was formed by coating and drying so that the solid coating amount after drying was 3 g / m ² .
Back layer coating solution-1
Polyvinyl acetal resin (trade name: ESREC KX-1, manufactured by Sekisui Chemical Co., Ltd.) 40 parts polyacrylic ester resin (trade name: Julimer AT613, manufactured by Nippon Pure Chemical) 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 an intermediate layer"
Next, the intermediate layer coating solution-1 having the following composition is applied on the surface opposite to the side on which the back surface layer of the sheet-like support is provided, and dried so that the film thickness after drying is 43 μm. An intermediate layer was formed.
Intermediate layer coating solution-1
Polyvinylidene chloride foamed hollow particles (volume hollow ratio 93%, average particle diameter 4 μm, maximum particle diameter 20 μm) 35 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 15 parts styrene-butadiene latex (trade name: PT1004, Japan) Zeon) 50 parts water 200 parts

"Creating a receiving sheet"
Further, on the intermediate layer, a barrier layer coating solution-1 having the following composition was applied and dried so that the solid content coating amount was 2 g / m ² , and a barrier layer was formed. The receiving layer coating liquid-1 having the following composition was applied and dried so that the solid coating amount was 5 g / m ² to form a receiving layer, and then cured at 50 ° C. for 48 hours. Furthermore, using a calender device comprising a preheating device, a metal heating roll and an elastic roll, and a thickness restoring roll, the receiving sheet temperature before nip treatment is 50 ° C., the metal heating roll temperature is 70 ° C., the nip time is 50 ms, the nip pressure is 10 MPa, the thickness is Smoothing treatment was performed under the conditions of a thickness restoration roll temperature of 70 ° C. and a thickness restoration time of 2 seconds to prepare a receiving sheet having an Rp value of 1.0 μm on the surface of the receiving layer.
Coating liquid for barrier layer-1
Polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray) 100 parts Water 1000 parts
Receiving layer coating solution-1
Polyester resin (trade name: Byron 200, manufactured by Toyobo,
Glass transition temperature: 67 ° C) 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 Co., Ltd.) 5 parts toluene / methyl ethyl ketone = 1/1 ( (Mass ratio) 400 parts of liquid mixture

Example 2
A receiving sheet was prepared in the same manner as in Example 1 except that the intermediate layer coating solution-2 was used in place of the intermediate layer coating solution-1. The Rp value on the surface of the receiving layer was 1.5 μm.
Intermediate layer coating liquid-2
Microcapsule 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%) 35 parts polyvinyl alcohol (product) Name: PVA205, made by Kuraray) 15 parts Styrene-butadiene latex (trade name: PT1004, made by Nippon Zeon) 50 parts Water 200 parts

Example 3
In the smoothing treatment step, a receiving sheet was prepared in the same manner as in Example 2 except that the receiving sheet temperature before the nip treatment by the preheating device was changed to 60 ° C. The Rp value on the surface of the receiving layer was 1.0 μm.

Example 4
After forming the intermediate layer, the intermediate layer surface smoothing process (same conditions as the smoothing process after forming the receiving layer in Example 1) is performed, and the barrier layer and the receiving layer are sequentially formed on the processed intermediate layer. A receiving sheet was prepared in the same manner as in Example 1 except that. However, the smoothing process after forming the receiving layer was omitted. The Rp value on the surface of the receiving layer was 2.0 μm.

Example 5
A receiving sheet was prepared in the same manner as in Example 1 except that the thickness restoring step was omitted in the smoothing treatment step. The Rp value on the surface of the receiving layer was 3.0 μm.

Example 6
In Example 1, an intermediate layer coating liquid-3 having the following composition was used instead of the intermediate layer coating liquid-1, and a receiving layer coating liquid-1 was used instead of the receiving layer coating liquid-1. 2 is used to form a receiving layer, and a calender device comprising a preheating device, a metal heating roll and an elastic roll, and a thickness restoring roll is used. Then, smoothing treatment was performed under the conditions of a nip time of 70 milliseconds, a nip pressure of 10 MPa, a thickness restoration roll temperature of 90 ° C., and a thickness restoration time of 2 seconds, to prepare a receiving sheet having an Rp value of 1.0 μm on the receiving layer surface.
Intermediate layer coating solution-3
Acrylonitrile-based foamed hollow particles (volume hollow ratio 80%, average particle size 2.8 μm) 40 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray) 10 parts styrene-butadiene latex (trade name: PT1004, manufactured by Nippon Zeon) 50 parts 200 parts of water
Receiving layer coating solution-2
Active hydrogen-containing vinyl chloride resin (trade name: VAGH, manufactured by Union Carbide,
Glass transition temperature: 77 ° C.) 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) 400 parts of liquid mixture

Comparative Example 1
In the smoothing process, a receiving sheet was prepared in the same manner as in Example 1 except that the receiving sheet temperature before the nip treatment by the preheating device was changed to 20 ° C. The Rp value on the surface of the receiving layer was 4.5 μm.

Comparative Example 2
In the smoothing process, a receiving sheet was prepared in the same manner as in Example 2 except that the receiving sheet temperature before the nip treatment by the preheating device was changed to 20 ° C. The Rp value on the surface of the receiving layer was 5.0 μm.

Reference example 1
In the smoothing process, the receiving sheet was the same as in Example 1 except that the temperature of the receiving sheet before the nip treatment by the preheating device was 20 ° C., and the nip time by the metal heating roll and the elastic roll was changed to 300 milliseconds. It was created. The Rp value on the surface of the receiving layer was 1.5 μm.

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 smoothness"
The static printing smoothness (Rp value) on the surface of the receiving layer was measured using a printing smoothness tester (trade name: Microtopograph, Toyo Seiki Seisakusho) at an applied pressure of 0.05 MPa.

"Print quality" (print density, image uniformity)
Using a commercially available thermal transfer video printer (trade name: UP-DR100, manufactured by Sony Corporation), an ink layer containing sublimable dyes of yellow, magenta, and cyan with each adhesive on a 6 μm thick polyester film. Each of the ink layers of the provided ink sheet is sequentially brought into contact with the receiving sheet and subjected to heat controlled stepwise by a thermal head, whereby a predetermined image is thermally transferred to the receiving sheet. A color-superimposed image was printed.

(Print density)
About the obtained recorded image, the reflection density was measured using the Macbeth reflection densitometer (brand name: RD-914, product made by Kollmorgen). 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 2.00 or higher, it is determined that the product has sufficient commercial value.

(Image uniformity)
Further, as an evaluation of the uniformity of the recorded image, visual observation was performed for the presence or absence of uneven density and white spots in a gradation portion corresponding to an optical density (black) of 0.3.
Excellent evaluation results were indicated by ◎, good results by ◯, dark unevenness and white spotting slightly recognized by Δ, and uneven density and white defect defects marked by x. It is judged that there is a commercial value above △.

  As is apparent from Table 1, the receiving sheet obtained in each example of the present invention had a sufficiently small Rp value on the surface of the receiving layer and good print quality such as print density and image uniformity. On the other hand, the receiving sheet of Comparative Example 1 or 2 has a large Rp value on the surface of the receiving layer, poor image uniformity, and insufficient print density. Further, it can be seen from Reference Example 1 that the nip time needs to be longer in order to sufficiently reduce the Rp value on the surface of the receiving layer without preheating before the nip treatment.

  The receiving sheet production method of the present invention is particularly suitable for dye thermal transfer printers, has an intermediate layer containing hollow particles, improves density unevenness, white spots, etc. It is possible to manufacture at a high speed and is practically valuable.

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

Claims (7)

  In the method for producing a thermal transfer receiving sheet, in which an intermediate layer having hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support, the intermediate layer is formed on at least one surface of the sheet-like support and / or an image. After the formation of the receiving layer, the surface temperature of the intermediate layer or the image receiving layer is adjusted to a range of 30 to 130 ° C., and smoothing treatment is performed through the nip portion of a pair of rolls composed of a metal heating roll and an elastic roll. A method for producing a thermal transfer receiving sheet.   The hollow particles have an average particle diameter of 0.2 to 30 μm and a volume hollowness of 25 to 95%, and are further measured at an applied pressure of 0.05 MPa using a microtopograph on the surface of the image receiving layer. The method for producing a thermal transfer receiving sheet according to claim 1, wherein the smoothing treatment is performed so that the static printing smoothness (Rp value) is 0 to 4.0 μm.   The method for producing a thermal transfer receiving sheet according to claim 1, wherein the surface temperature is adjusted by contacting the surface of the metal heating roll before passing through the nip portion.   The method for producing a thermal transfer receiving sheet according to claim 1, wherein the surface temperature is adjusted using a preheating roll.   The thermal transfer according to any one of claims 1 to 4, wherein after the smoothing treatment, the intermediate layer or the image receiving layer is brought into contact with a heating roll in a pressure-released state to perform a thickness restoration treatment. A method for producing a receiving sheet.   The method for producing a thermal transfer receiving sheet according to claim 1, wherein the image receiving layer contains a vinyl chloride resin as a main component. The method for producing a thermal transfer receiving sheet according to claim 6, wherein the vinyl chloride resin is a vinyl chloride resin having active hydrogen.

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