JP2009196279A - Thermal transfer image receiving sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily obtain a thermal transfer image receiving sheet which can form a printed matter having reduced voids even after preservation for a long time in a relatively high temperature environment. <P>SOLUTION: The thermal transfer image receiving sheet 1 is obtained by laminating a dye acceptance layer 3 on the face of a base material sheet 2 via a porous layer 4. The porous layer 4 comprises a binder and hollow particles, and the binder is composed of a resin material exhibiting rubber elasticity and a gelling agent. In this way, the thermal transfer image receiving sheet 1 which can form a printed matter having reduced voids even after preservation for a long time in a relatively high temperature environment can be easily obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal transfer image receiving sheet used for printing by a sublimation thermal transfer system.

  As a method of forming an image using thermal transfer, a thermal transfer sheet in which a thermal diffusion dye (sublimation dye) as a recording material is carried on a base sheet such as a plastic film, and another base such as paper or plastic film A thermal diffusion transfer system (sublimation thermal transfer system) is known in which a thermal transfer image receiving sheet provided with a receiving layer on a sheet is superposed on each other to form a full color image. Since this method uses a thermal diffusion dye as a color material, the density and gradation can be freely adjusted in dot units, and a full-color image exactly as the original can be clearly displayed on the image-receiving sheet. It is applied to color image formation for computers and the like. The image is of a high quality comparable to a silver salt photograph.

  The thermal transfer image-receiving sheet has a configuration in which a plurality of layers are laminated on a base material sheet. As a method for producing such a thermal transfer image-receiving sheet, for example, by gravure coating or the like, A method of sequentially forming a porous layer and a receiving layer is known. However, since this method is a method of sequentially forming each layer, there is a problem that the number of steps increases. Therefore, in order to obtain a thermal transfer image-receiving sheet with a smaller number of steps, for example, using a slide coating method or the like that applies the coating liquid constituting each layer on the base sheet while being stacked one above the other on the base sheet. A method of simultaneously forming a plurality of layers (simultaneous multilayer coating method) has been attracting attention (for example, Patent Documents 1 to 3). Such a method is extremely advantageous in that the production efficiency can be remarkably improved by simultaneously forming a plurality of layers, which contributes to the reduction of the production cost.

  By the way, there is a problem of occurrence of a phenomenon of “white-out” with respect to forming a print on a thermal transfer image receiving sheet by a sublimation thermal transfer system using a thermal transfer sheet. “White blank” indicates that when a printed matter is created using a thermal transfer image receiving sheet, a region that is not partially printed occurs in the region to be printed on the thermal transfer image receiving sheet. The main cause of the occurrence of “white spots” is that the surface of the substrate sheet or the porous layer has an uneven shape, and the uneven shape forms an uneven shape on the surface of the thermal transfer image-receiving sheet. Can be mentioned. That is, when printing on a thermal transfer image receiving sheet by a sublimation thermal transfer system, the dye of the thermal transfer sheet is transferred to a predetermined area of the thermal transfer image receiving sheet by heating by a heating means such as a thermal head, but the surface of the thermal transfer image receiving sheet is uneven. If there is a shape, the unevenness of the shape hinders the adhesion (follow-up property) between the thermal transfer sheet and the thermal head, and a region where heat cannot be sufficiently transferred from the thermal head partially occurs on the thermal transfer sheet or thermal transfer image receiving sheet. Resulting in. Then, “white spots” occur in the area where the heat is not sufficiently transmitted, and this “white spots” makes the entire printed image an image having “roughness” (graininess).

  This “white spot” problem, ie, “roughness” problem, is particularly likely to occur when a thermal transfer image-receiving sheet is formed by the simultaneous multilayer coating method using the slide coating method. In the simultaneous multi-layer coating method by the slide coating method, each layer formed on the base sheet is produced at the same time by the coating film formed at the same time, so that the uneven state of the surface shape of the base sheet remains as it is. The surface shape of the layer exposed on the outermost surface tends to be uneven, and the conventional thermal transfer image-receiving sheet has insufficient cushioning properties, so it is difficult to absorb the uneven shape on the surface of the base sheet. If there is an uneven shape on the surface of the material sheet, it is easily reflected as it is on the surface shape of the outermost dye receiving layer of the thermal transfer image receiving sheet. Thus, particularly when the thermal transfer image-receiving sheet is formed by the simultaneous multi-layer coating method by the slide coating method, there is a serious problem that it may cause “roughness”.

  In addition, when the thermal transfer image receiving sheet is used by being transported far from the production site, the thermal transfer image receiving sheet is used after being stored for a long time under a relatively high temperature environment. Under the environment, the unevenness of the surface of the thermal transfer image-receiving sheet tends to increase due to the shrinkage of the paper of the paper base material, and this has exacerbated the “roughness” problem.

JP 2006-88691 A JP-A-6-171240 JP 2006-103040 A

  The present invention can be manufactured with high efficiency by simultaneously forming a plurality of layers on a substrate sheet, and is white even after being stored for a long time under a relatively high temperature environment. The main object of the present invention is to provide a thermal transfer image-receiving sheet capable of forming a small number of prints.

  The present invention is (1) a thermal transfer image-receiving sheet obtained by laminating a dye-receiving layer on a surface of a substrate sheet via a porous layer, the porous layer comprising a binder and hollow particles, Is a thermal transfer image-receiving sheet comprising a resin material exhibiting rubber elasticity and a gelling agent. (2) The binder has rubber elasticity with a glass transition temperature (Tg) of 0 ° C. or less. (3) The binder includes a resin material exhibiting rubber elasticity composed of styrene butadiene rubber (SBR) or methyl methacrylate butadiene rubber (MBR). The thermal transfer image-receiving sheet according to the above (1) or (2), (4) The binder contains a resin material exhibiting rubber elasticity in a range of 10 wt% to 30 wt%. The thermal transfer image-receiving sheet according to any one of (1) to (3) above, (5) The porous layer has a binder content: a hollow particle content = 40 to 10 parts by weight: 60 to 90 parts by weight. The gist is the thermal transfer image-receiving sheet according to any one of (1) to (4), which comprises a binder and hollow particles at a mixing ratio of parts.

  The present invention is advantageous in that a thermal transfer image-receiving sheet can be obtained on which a plurality of layers can be simultaneously formed on a base sheet, and a printed matter with reduced roughness can be formed.

  According to the present invention, the porous layer has excellent cushioning properties with hollow particles, and the porous layer includes a resin material having rubber elasticity, thereby further improving the cushioning property of the entire thermal transfer image-receiving sheet. Can be realized. Then, according to the present invention, even when the surface of the base sheet constituting the thermal transfer image receiving sheet has an uneven shape, when the thermal head is pressed against the overlapping thermal transfer sheet and the thermal transfer image receiving sheet, The uneven shape of the thermal transfer image receiving sheet is effectively absorbed by the pressing force of the thermal head, and heat from the thermal head is sufficiently applied to a predetermined area of the thermal transfer image receiving sheet. Even after the thermal transfer image receiving sheet has been subjected to storage processing for a long time in a relatively high temperature environment, the occurrence of “roughness” of the image is also reduced for the thermal transfer image receiving sheet after the storage processing. It becomes possible. Therefore, when producing a printed matter using the thermal transfer image-receiving sheet of the present invention, the followability of the thermal head to the receiving layer can be improved, and the occurrence of “roughness” during printing can be effectively suppressed. it can.

  According to the present invention, a binder is formed using a resin material having a low glass transition temperature (Tg), and the thermal transfer image receiving sheet is made of a resin material having a low glass transition temperature (Tg), which is a highly cushioning material. The cushioning property of itself can be improved more effectively. Further, since the thermal transfer image receiving sheet becomes more excellent in cushioning properties, it is possible to more effectively suppress the occurrence of “roughness” during printing.

  In addition, according to this invention, a binder can be comprised including SBR and gelatin, and the cushioning property of a porous layer can be improved further.

  Hereinafter, the thermal transfer image receiving sheet of the present invention will be described.

  As shown in FIG. 1A, the present invention is a thermal transfer image receiving sheet 1 in which a dye receiving layer 3 is laminated on a surface of a base sheet 2 with a porous layer 4 interposed therebetween.

<About the base material sheet 2>
The base sheet 2 has a function as a support for supporting the porous layer 4 and the dye receiving layer 3.

  The substrate sheet 2 used in the present invention is not particularly limited as long as it has heat resistance against heat given from the heating means during printing by thermal transfer using the thermal transfer image-receiving sheet 1. Specific examples include resin-coated paper, resin film base, and paper base, among which resin-coated paper is preferable.

  Resin-coated paper is usually formed by laminating a base resin layer on both sides of a base paper. Examples of the base paper constituting the base paper include natural pulp, synthetic pulp, and pulp paper made from a mixture thereof. Among these, it is preferable to use paper mainly composed of wood pulp. The base paper may be subjected to a conventionally known process such as a calendar process to be described later if necessary.

  The base paper preferably has a thickness in the range of 10 μm to 1000 μm, and more preferably in the range of 50 μm to 300 μm.

  The base paper can be produced by a known method, but a base paper that is calendered is preferable. This is because when a base paper that has been calendered is used for the base paper, the smoothness can be improved and the glossiness of the resulting thermal transfer image-receiving sheet can be enhanced.

  The resin for forming the base resin layer is preferably a resin that can form a base resin layer with a small neck-in and good drawdown property, such as polyolefin resin, polystyrene resin, vinyl, and the like. Resin, polyester resin, ionomer resin, nylon, polyurethane and the like, and polyolefin resin is preferable in that a base resin layer excellent in water resistance, strength, gloss and the like can be obtained.

  Examples of the polyolefin resin include high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, polybutene, and polypentene. Among these, high-density polyethylene, medium-density polyethylene, low-density polyethylene, and polypropylene are preferable, and polypropylene is particularly preferable. Is preferred.

  The base resin layer may be a film or sheet obtained by mixing one or two or more of the above-described resins, or a film prepared by adding a pigment, a filler, or the like in addition to the resin or It may be a sheet. Further, the resin may be one obtained by blending an additive such as a modifier to improve adhesiveness. Examples of the modifier include olefin copolymers such as Tuffmer (manufactured by Mitsui Chemicals).

  The resin-coated paper can be produced by laminating a base resin layer on both sides of a base paper by a known laminating method such as dry lamination, wet lamination, or extrusion. The base paper can be appropriately subjected to primer treatment or corona discharge treatment on the surface for the purpose of improving the interlayer adhesion between the base paper and the base resin layer.

  The thickness of the resin-coated paper is, for example, preferably in the range of 10 μm to 1000 μm, and more preferably in the range of 50 μm to 300 μm, with respect to the total thickness.

  Examples of the resin film base include polyester, polyacrylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivative, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polystyrene, acrylic, polyvinyl chloride, and polychlorinated. Vinylidene, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene, perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene-ethylene, tetrafluoroethylene-hexafluoropropylene, poly Examples include chlorotrifluoroethylene and polyvinylidene fluoride. Among these, in the present invention, polyethylene terephthalate and polypropylene resin can be preferably used.

  The thickness of the resin film substrate is preferably, for example, in the range of 20 μm to 100 μm, more preferably in the range of 25 μm to 60 μm, and particularly preferably in the range of 30 μm to 50 μm.

  Examples of paper base materials include condenser paper, glassine paper, sulfuric acid paper, high-size paper, synthetic paper (polyolefin-based, polystyrene-based), high-quality paper, art paper, coated paper, cast-coated paper, and wallpaper. , Backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, paperboard, cellulose fiber paper and the like.

  The thickness of the paper substrate is preferably, for example, in the range of 80 μm to 400 μm, in particular in the range of 100 μm to 200 μm, particularly in the range of 100 μm to 210 μm.

<Dye-receiving layer 3>
The dye receiving layer 3 is a layer containing a resin material (receiving layer forming resin) having dye dyeing properties, and the dye carried on the thermal transfer sheet when the transfer image receiving sheet 1 is printed by thermal transfer. Is transferred to a predetermined area of the thermal transfer image receiving sheet, and the dye is carried on the thermal transfer image receiving sheet 1 (the thermal transfer image receiving sheet 1 is dyed), and has a function of forming an image on the thermal transfer image receiving sheet 1. .

  The receiving layer forming resin is not particularly limited as long as it has dye dyeing properties. Among them, the receptor layer-forming resin used in the present invention preferably has a glass transition temperature (Tg) of 20 ° C. or higher, more preferably 30 ° C. or higher, and even more preferably 40 ° C. or higher. . The receptor layer-forming resin preferably has a glass transition temperature of 120 ° C. or lower. This is because by using a receiving layer forming resin having a glass transition temperature in such a range, a thermal transfer image receiving sheet having particularly excellent heat resistance and releasability can be obtained.

  In this specification, the glass transition temperature (Tg) is measured by the elastic modulus by the DMA method using a rigid pendulum type surface physical property tester (RPT3000W manufactured by A & D, temperature rising rate 3 ° C./min), and the peak The point where can be confirmed was defined as Tg.

  The resin for forming the receiving layer can be either a resin that can be dispersed / dissolved in an aqueous solvent (aqueous resin) or a resin that can be dispersed / dissolved in an organic solvent (solvent resin), but it should be an aqueous resin. preferable. When the thermal transfer image-receiving sheet of the present invention is produced by using the aqueous resin as the receptor layer-forming resin, the porous layer and the receptor layer are simultaneously formed on the substrate sheet using only an aqueous solvent. This is because it can be applied.

  Here, in this specification, “aqueous solvent” refers to a solvent containing water as a main component. The ratio of water in the aqueous solvent is usually 60% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more. Examples of solvents other than water include alcohols such as methanol, ethanol, isopropanol, and n-propanol; glycols such as ethylene glycol, diethylene glycol, and glycerin; esters such as ethyl acetate and propyl acetate; ketones such as acetone and methyl ethyl ketone. And amides such as N, N-dimethylformamide, etc., which are not easily phase-separated in the presence of water. Examples of the “organic solvent” include a liquid made of an organic compound that undergoes phase separation in the presence of water.

  The aqueous resin constituting the receiving layer forming resin is not particularly limited as long as a predetermined amount can be dispersed and dissolved in a desired aqueous solvent. Examples of such aqueous resins include polyolefin resins, polyvinyl resins, polyester resins, polyurethane resins, polycarbonate resins, polyamide resins, poly (meth) acrylic acid resins, cellulose derivative resins, or polyether resins. Etc. In the present invention, any of these water-based resins can be suitably used, and among these, it is preferable to use a polyvinyl resin.

  Examples of the polyvinyl resin include vinyl chloride / vinyl acetate copolymer, vinyl chloride / acrylic compound copolymer, ethylene / vinyl chloride / acrylic ester copolymer, ethylene / vinyl acetate / vinyl chloride copolymer, and the like. Can be mentioned as preferred.

  The vinyl chloride / vinyl acetate copolymer is not particularly limited as long as it is a copolymer composed of vinyl chloride and vinyl acetate, and can be copolymerized with these essential monomers in addition to vinyl chloride and vinyl acetate. It may be obtained by polymerizing a small amount of monomers.

  The vinyl chloride / acrylic compound copolymer is not particularly limited as long as it is a copolymer composed of vinyl chloride and an acrylic compound, and a single amount copolymerizable with these essential monomers in addition to vinyl chloride and an acrylic compound. The body may be obtained by copolymerization in a small amount. In the present specification, “acrylic compound” means (meth) acrylic acid and / or an alkyl ester thereof.

  Examples of the acrylic compound include acrylic acid; acrylic acid salts such as calcium acrylate, zinc acrylate, magnesium acrylate, and aluminum acrylate; methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and 2-ethoxyethyl. Acrylates such as acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, trimethylolpropane triacrylate; methacrylic acid; methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate, Cyclohexyl methacrylate, triethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, trimethylol trimethacrylate It can be mentioned methacrylic acid esters of bread, etc., and the like.

  The ethylene / vinyl chloride / acrylic acid ester copolymer and the ethylene / vinyl acetate / vinyl chloride copolymer (hereinafter, these copolymers are collectively referred to as “ethylene / vinyl chloride copolymer”). Is not particularly limited as long as it is a copolymer obtained by polymerizing at least three monomers of ethylene, vinyl chloride and acrylate, or three monomers of ethylene, vinyl acetate and vinyl chloride. In addition to these three types of monomers, a small amount of a small amount of monomer may be copolymerized.

  The ethylene / vinyl acetate / vinyl chloride copolymer may be a copolymer of ethylene / vinyl acetate copolymer (EVA) and vinyl chloride. As the EVA / vinyl chloride copolymer, EVA may be used. It may be a graft copolymerized vinyl chloride. EVA includes those in which all or part of vinyl acetate units in the copolymer is saponified.

  In the present invention, “acrylic acid ester” constituting the ethylene / vinyl chloride / acrylic acid ester copolymer is a concept including a methacrylic acid ester in addition to the acrylic acid ester. Examples of the acrylic acid ester include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethoxyethyl acrylate, 2-hydroxyethyl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, and trimethylolpropane triacrylate. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, tridecyl methacrylate, cyclohexyl methacrylate, triethylene glycol dimethacrylate, dimethacrylic acid-1, Examples include 3-butylene and trimethylolpropane trimethacrylate.

  As the resin for forming the receiving layer, only one kind of various resins as described above may be used, or two or more kinds of resins having different monomer compositions, average molecular weights, and the like may be used.

  The dye receiving layer 3 may include a receiving layer forming resin and may include other compounds as necessary. For example, the dye receiving layer 3 may include a cooling gelling agent as “another compound”.

  The cooling gelling agent contained in the dye-receiving layer 3 has a property of gelling when cooled, and is particularly limited as long as it can impart viscosity characteristics to the dye-receiving layer-forming coating film. Is not to be done. Examples of such a cooling gelling agent include gelatin, polyvinyl alcohol, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, pectin and the like.

  Here, the gelatin is composed of a peptide chain obtained by denaturing collagen having a triple helix structure as described above, and partially recovers the triple helix structure by cooling, By forming a three-dimensional network starting from the recovered triple helix structure, it exhibits cooling gelation characteristics.

The polyvinyl alcohol is usually used in combination with Na ₂ B ₄ O ₇ and forms a three-dimensional network starting from the hydrogen bond by forming hydrogen bonds with tetraborate ions, thereby providing a cooling gelation characteristic. It is shown.

  The above-mentioned κ-carrageenan, λ-carrageenan, and ι-carrageenan are natural polymer compounds mainly composed of galactose and 3,6-anhydrogalactose having a molecular weight of about 100,000 to 500,000 extracted from red algae seaweed. It is characterized by having a half-ester type sulfate group in the molecule, and usually exhibits a cooling gelation property when a thickener such as locust bean gum or carbonate is used in combination. .

  The pectin is a natural polysaccharide that constitutes a cell wall of a plant, and exhibits cooling gelation characteristics when used in combination with an ionic compound.

  Any of the cooling gelling agents contained in the dye receiving layer 3 can be suitably used. Moreover, the cooling gelling agent may use only 1 type from what was illustrated above, and may be used in combination of 2 or more types.

  When the dye-receiving layer 3 contains a cooling gelling agent, the content of the cooling gelling agent in the dye-receiving layer 3 is such that when the thermal transfer image-receiving sheet 1 is produced, the receiving layer contains a resin constituting the dye-receiving layer 3. There is no particular limitation as long as the desired viscosity characteristics can be imparted to the forming coating liquid. Specifically, the cooling gelling agent is preferably in the range of 1 part by weight to 100 parts by weight, particularly 1 part by weight to 40 parts by weight, with respect to 100 parts by weight of the resin for forming the receiving layer. It is preferable that it is in the range of 2 parts by weight or more and 40 parts by weight or less. When the content of the cooling gelling agent is less than the above range, for example, in the case of producing the thermal transfer image receiving sheet 1 by the simultaneous multilayer coating method, a porous forming coating film for forming the porous layer 4 And a dye-receiving layer forming layer when a coating film for forming a dye-receiving layer for forming a dye-receiving layer 3 is formed so as to overlap on a base sheet. This is because the two layers of the coating film may be mixed. Further, when the content of the cooling gelling agent is larger than the above range, the coating for forming the receiving layer forming coating film is formed when the receiving layer forming coating film is applied and formed on the base sheet. Depending on the viscosity of the liquid, there may be cases where coating lines and uneven coating are likely to occur on the surface of the coating film for forming the receiving layer.

  In addition to the cooling gelling agent, for example, a release agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a pigment, an antistatic agent, a plasticizer, a hot-melt material, etc. May be included.

  Examples of the release agent include known ones such as silicone oil, phosphate ester compounds, and fluorine compounds, and silicone oil is particularly preferable. Examples of silicone oil include epoxy-modified silicone oil, alkyl-modified silicone oil, amino-modified silicone oil, fluorine-modified silicone oil, phenyl-modified silicone oil, epoxy / polyether-modified silicone oil, vinyl-modified silicone oil, and hydrogen-modified silicone oil. Modified silicone oil is preferred. The release agent is preferably added so as to be in the range of 0.5 to 30 parts by mass with respect to 100 parts by mass of the above-described receptor layer forming resin.

  With respect to the surface roughness of the dye receiving layer 3, the surface roughness difference at the reference position is within an average value (SPa) of 0 μm to 3 μm, more preferably 0 μm, with the center of gravity in the in-plane direction of the dye receiving layer 3 as the reference position. ˜2 μm, more preferably in the range of 0 μm to 1 μm.

  The thickness of the dye receiving layer 3 is not particularly limited as long as it is within a range in which a desired printing sensitivity can be expressed according to the resin for forming the receiving layer, but is within a range of 0.5 μm to 30 μm. In particular, it is preferably in the range of 0.5 μm to 20 μm, and more preferably in the range of 1 μm to 15 μm.

<About porous layer 4>
The porous layer 4 is a layer formed between the base material sheet 2 and the dye receiving layer 3. When printing is performed on the thermal transfer image receiving sheet 1 by thermal transfer, the porous layer 4 is heated by heating means such as a thermal head. The heat transfer image receiving sheet 1 has a heat insulating function for suppressing and blocking heat applied to a predetermined region of the dye receiving layer 3 from being easily diffused from the dye receiving layer 3 to the base sheet 2 or the like. The heat given from the thermal head does not diffuse immediately from the dye receiving layer 3 to the base sheet 2 or the like, but stays in the dye receiving layer 3 for a certain period of time, thereby effectively receiving the sublimation dye supported on the thermal transfer sheet. Thermal transfer to the layer is realized.

  The heat insulating property of the porous layer 4 can be adjusted to an arbitrary range by changing the porosity and thickness of the porous layer.

  The thickness of the porous layer 4 is not particularly limited as long as the above heat insulating property and buffer property can be adjusted to a desired level, but specifically, the thickness may be within a range of 10 μm to 100 μm. Preferably, it is in the range of 10 μm to 50 μm.

  The specific gravity of the porous layer 4 is preferably in the range of 0.2 to 0.7, and more preferably in the range of 0.4 to 0.7. When the specific gravity of the porous layer 4 is within this range, a sufficient volume of voids is formed in the porous layer 4, and the function of increasing the sensitivity of the thermal transfer image-receiving sheet 1 can be effectively exhibited in the porous layer 4. Become.

The specific gravity of the porous layer 4 was determined from the film thickness R (μm) of the porous layer and the coating amount Q (weight / area) (g / m ² ) of the porous layer. The specific gravity of the porous layer 4 was determined by Q / R.

  The porous layer 4 includes hollow particles and a binder.

(1) About hollow particles The hollow particles contained in the porous layer 4 are particles having a space portion therein, and by providing the space portion in the porous layer 4, the porous layer 4 has a heat insulating function. It is given. Therefore, the hollow particles are not particularly limited as long as the desired heat insulating properties can be imparted to the porous layer 4.

  The hollow particles may be either expanded particles or non-expanded particles. Further, the expanded particles may be independent expanded particles or continuous expanded particles. Furthermore, the hollow particles used in the present invention may be organic hollow particles composed of a resin material or the like, or inorganic hollow particles composed of glass or the like. Further, the hollow particles may be made of a resin material that has been made into a crosslinked polymer.

  Examples of the resin material constituting the hollow particles include styrene resins such as crosslinked styrene-acrylic resins, (meth) acrylic resins such as acrylonitrile-acrylic resins, phenolic resins, fluorine resins, polyamide resins, and polyimides. Resin, polycarbonate resin, polyether resin and the like.

  The average particle diameter of the hollow particles is not particularly limited as long as the desired heat insulating property and cushioning property can be imparted to the porous layer depending on the type of resin constituting the hollow particles, etc. , Preferably in the range of 0.1 μm to 15 μm, particularly preferably in the range of 0.1 μm to 10 μm. If the average particle size is too small, the amount of hollow particles used increases and the cost increases, and the outer shell thickness cannot be adjusted below the thickness necessary for maintaining the voids inside the hollow particles. The porosity of the particles themselves is smaller than that of the particles, and as a result, the porosity of the hollow particle layer cannot be increased. If the average particle size is too large, it becomes difficult to form a smooth porous layer 4. Because.

  In the present specification, the “average particle diameter” is obtained as follows. A water dispersion is prepared by dispersing hollow particles in water, and the water dispersion of the hollow particles is dried to form a dry body, and then dried with a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation). The particles (100 particles) forming the hollow particles in the body were observed, the diameter (outer diameter) on the outer surface side of each particle was measured, and these values were averaged to obtain the average particle diameter.

  In the present invention, the amount of solid content of the hollow particles contained in the porous layer 4 is not particularly limited as long as the porous layer 4 having desired heat insulating properties and buffering properties can be obtained. It is preferable to be within the range of parts by weight to 90 parts by weight, and it is particularly preferable to be within the range of 50 parts by weight to 80 parts by weight. If the content is too small, the voids in the porous layer 4 may decrease, and sufficient heat insulating properties and cushioning properties may not be obtained. If the content is too large, the base material sheet constituting the thermal transfer image-receiving sheet 1 and There is a risk that the adhesion between the porous layer and the dye-receiving layer may be lowered.

(2) Binder <Resin material showing rubber elasticity>
The binder included in the porous layer 4 includes a resin material exhibiting rubber elasticity. The resin material exhibiting rubber elasticity is a resin material having a glass transition temperature (Tg) of 0 ° C. or lower, and preferably has a Tg in the range of −80 ° C. to 0 ° C., particularly −60 ° C. to 0 ° C. It is preferably within the range, and more preferably within the range of −40 ° C. to 0 ° C. This is because if Tg is higher than the above range, it may be difficult to impart desired elasticity to the cushion layer. Moreover, when lower than the said range, there exists a possibility that mixing with the layer adjacent to a cushion layer may arise.

  As the resin material exhibiting rubber elasticity, at least one of styrene / butadiene rubber (SBR) or methyl methacrylate / butadiene rubber (MBR) is selected.

  Examples of SBR include emulsion-polymerized styrene / butadiene rubber, solution-polymerized styrene / butadiene rubber, non-oil-extended styrene / butadiene rubber, and oil-extended styrene / butadiene rubber.

  The resin material exhibiting rubber elasticity is not particularly limited as long as the porous layer 4 having desired elasticity can be produced according to the type and content of the cooling gelling agent. Specifically, the resin material exhibiting rubber elasticity is preferably contained in an amount of 10 to 40% by weight, more preferably 10 to 30% by weight, based on the total amount of the binder. When there is more content of the resin material which shows rubber elasticity than the said range, there exists a possibility that formation of the coating film for porous layer formation expected to become a porous layer may be impaired. Moreover, when content of the resin material which shows rubber elasticity is less than the said range, it may become difficult to provide desired elasticity to a porous layer.

  As the binder, a water-based resin (excluding a resin material exhibiting rubber elasticity) is usually used as a material other than the resin material exhibiting rubber elasticity. Examples of such water-based resins include polyurethane resins such as acrylic urethane resins, polyester resins, gelatin, polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, pullulan, carboxymethyl cellulose, hydroxyethyl cellulose, dextran, dextrin, and polyacrylic acid. And salts thereof, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan, casein, xanthene gum, locust bean gum, alginic acid, gum arabic, and those described in JP-A-7-195826 and 7-9757. Homopolymerization of a real xylene oxide copolymer, water-soluble polyvinyl butyral, or a vinyl monomer having a carboxyl group or a sulfonic acid group described in JP-A-62-245260 And copolymers and the like. Moreover, you may use in combination of 2 or more types of the said resin.

<About cooling gelling agent>
The binder contained in the porous layer 4 includes a cooling gelling agent such as gelatin. The cooling gelling agent has a property of gelling the liquid to which the liquid added is cooled (gelling agent), and the porous layer is applied to the coating film for forming the porous layer. It has a viscosity. The cooling gelling agent preferably has a viscosity at 15 ° C. in a state dissolved in water of 3 times or more, particularly 5 times or more, more preferably 10 times or more of the viscosity at 80 ° C.

  The cooling gelling agent constituting the binder can be appropriately used from those described above as usable when the dye-receiving layer 3 contains a cooling gelling agent. Therefore, for example, gelatin, polyvinyl alcohol, agar, Examples thereof include gelling agents such as κ-carrageenan, λ-carrageenan, ι-carrageenan, and pectin. Here, gelatin is composed of a peptide chain obtained by denaturing collagen having a triple helix structure as described above, and partially recovers and recovers the triple helix structure by cooling. By forming a three-dimensional network with the triple helix structure as a starting point, a cooling gelation characteristic is exhibited. Further, κ-carrageenan, λ-carrageenan and ι-carrageenan are natural polymer compounds mainly composed of galactose and 3,6-anhydrogalactose having a molecular weight of about 100,000 to 500,000 extracted from red algae seaweed. . It is characterized by having a half-ester type sulfate group in the molecule, and usually exhibits a gelling property by using a thickener such as locust bean gum or a metal salt compound in combination. is there. Pectin is a natural polysaccharide that constitutes the cell wall of plants, and exhibits cooling gelation characteristics when used in combination with an ionic compound.

  Any kind of the cooling gelling agent described above can be suitably used, and only one kind may be used, or two or more kinds may be used in combination.

  The blending ratio of the hollow particles contained in the porous layer 4 and the cooling gelling agent is not particularly limited as long as the porous layer 4 having desired heat insulating properties can be formed. Specifically, the cooling gelling agent is preferably in the range of 10 to 50 parts by weight, particularly in the range of 10 to 40 parts by weight with respect to 100 parts by weight of the solid content constituting the porous layer 4. It is preferable that When the content ratio of the hollow particles and the cooling gelling agent is within the above range, the porous layer 4 having excellent heat insulating properties can be formed.

  In the present invention, the thermal transfer image-receiving sheet 1 is more excellent in elasticity by the porous layer 4, and the cooling gelling agent contained in the binder constituting the porous layer 4 and the resin material having rubber elasticity. It is preferable that the combination is gelatin and SBR, respectively. In this case, gelatin derived from various raw materials such as beef bone gelatin (ossein gelatin), cow skin gelatin, pig skin gelatin, and fish skin gelatin that are generally used for industrial use is known. However, in the present invention, any gelatin derived from any raw material can be suitably used. Among them, bovine bone gelatin (Ocein gelatin) is preferable. Further, gelatin that is generally used industrially is classified into alkali-treated gelatin, acid-treated gelatin, enzyme-treated gelatin, piperazine-treated gelatin, etc., depending on the production method when extracted from the above-mentioned raw materials. However, in the present invention, gelatin extracted by any of these production methods can be preferably used. Of these, alkali-treated gelatin is preferred in the present invention. This is because the use of the alkali-treated gelatin reduces the viscosity, and the use of the acid-treated gelatin may increase the viscosity.

  The gelatin preferably has a weight average molecular weight in the range of 10,000 to 1,000,000. This is because if the molecular weight of gelatin is larger than the above range, the viscosity becomes high, and coating stripes and uneven coating may occur in the coating film for forming a porous layer. Further, when the molecular weight of gelatin is less than the above range, the thermal transfer image receiving sheet 1 is produced. Thus, the layers constituting the thermal transfer image receiving sheet 1 (dye receiving layer 3 and porous layer 4) are simultaneously formed by the simultaneous multilayer coating method. In the case of forming, the layers such as the layer of the porous layer forming coating film and the layer of the dye receiving layer forming coating film applied and formed on the base sheet are likely to be mixed with each other.

  Two or more types of gelatin having different weight average molecular weights may be used in combination, or only one type having a predetermined weight average molecular weight may be used.

  In addition to containing hollow particles and a binder, the porous layer 4 contains, for example, a nonionic silicone-based surfactant, a curing agent such as an isocyanate compound, a wetting agent, a dispersing agent, and the like. It may be included.

  In the example shown in FIG. 1A, the case where the thermal transfer image receiving sheet 1 has a single porous layer 4 is described as an example. However, the present invention is not limited to this, and the thermal transfer image receiving sheet 1 is porous. It may be formed by forming a plurality of quality layers. In this case, the plurality of porous layers may have the same composition or may have different compositions. When the thermal transfer image-receiving sheet 1 forms a plurality of porous layers, the plurality of porous layers 4 preferably have different compositions. By setting it as such a structure, the thermal transfer image receiving sheet 1 can further have a functional porous layer.

  For example, as an example of the case where the thermal transfer image-receiving sheet 1 has two porous layers, the porous layer A containing the hollow particles a is laminated on the surface of the base material sheet 2, and the surface of the porous layer A is The thing which has the structure by which the porous layer B containing the hollow particle b whose hollow rate is smaller than the hollow particle a was laminated | stacked can be mentioned. When the thermal transfer image-receiving sheet 1 includes two such porous layers, it is possible to more effectively prevent the occurrence of density unevenness and white spots in highlight portions during printing.

<About the manufacturing method of the thermal transfer image receiving sheet 1>
The thermal transfer image receiving sheet 1 of the present invention can be generally produced using a known method as a method for producing a thermal transfer image receiving sheet.

  The thermal transfer image-receiving sheet 1 can be produced by a method of individually laminating each layer, or by a method of simultaneously laminating each layer formed on the base sheet 2 of the thermal transfer image-receiving sheet 1 by a simultaneous multilayer coating method. Can be produced.

  The manufacturing method of the thermal transfer image-receiving sheet 1 by the simultaneous multilayer coating method can be carried out as follows.

<Adjustment of coating solution>
A hollow particle is selected and a binder containing a cooling gelling agent and a resin material exhibiting a predetermined rubber elasticity is prepared. These hollow particles and binder are dispersed and dissolved in an aqueous solvent to form a coating liquid (porous layer formation). Coating liquid) is adjusted. In addition, a predetermined resin material is selected as the resin material constituting the dye-receiving layer, and a cooling gelling agent is further selected. These resin material and cooling gelling agent are dispersed and dissolved in an aqueous solvent, and the coating liquid (Receiving layer forming coating solution) is adjusted. In addition, the temperature of the coating liquid at the time of apply | coating each coating liquid on a base material sheet shall be in the range of 40 to 80 degreeC normally.

<Production of coating film>
By applying the coating liquid for forming the porous layer and the coating liquid for forming the receiving layer on the base sheet while being stacked one above the other by the slide coating method, two coating films (for forming the porous layer) Coating film and receiving layer forming coating film) are produced simultaneously. At this time, a porous layer is formed by applying a coating liquid for forming a porous layer between a base sheet and a coating film for forming a receiving layer prepared by applying a coating liquid for forming a receiving layer. A coating film is produced.

  The slide coating method is performed using, for example, a coating apparatus including a roll (back roll) around which the base sheet 2 is wound and a die head having a slit nozzle that discharges the coating liquid toward the rotating surface of the roll. can do. In this case, the die head is formed in such a shape that the slit nozzle is ejected with a plurality of types of coating liquids stacked one above the other. According to such a coating apparatus, the back roll causes the base sheet to face the die head while partially winding the base sheet 2 and feeds the base sheet 2 in the rotation direction of the back roll. A plurality of coating liquids constituting each layer of the thermal transfer image-receiving sheet 1 are discharged onto the substrate sheet surface 2 in a state of being vertically stacked.

  The slide coating method is excellent in film thickness uniformity, and the coating liquid is not scattered because no centrifugal force is applied in the in-plane direction of the coating film due to rotation compared to the application of the coating liquid by the spin coating method. It is difficult to cause quality defects due to the above, and since there is no friction part compared to the application of the coating liquid by the roll coating method, there is an advantage that loss due to the occurrence of a raw fabric cut at the application part is less likely to occur. Also, from the viewpoint of handling properties of the coating liquid, the slide coating method can use a coating liquid that is less likely to change in concentration, viscosity, and composition of the coating liquid and that has high reactivity and changes over time. The coating liquid can be used up and waste is hardly generated, and a high solid content coating liquid can be used, and the amount of solvent used can be reduced.

  In the slide coating method, the difference in surface tension between the two coating liquids is usually within a certain range so that the porous layer forming coating liquid and the receiving layer forming coating liquid are not mixed with each other. To be adjusted.

  Next, the coating film formed on the base material sheet 2 is cooled (cooling process).

  In the cooling process, as a method of cooling the coating film formed on the base sheet 2, for example, the surface of a roll that transports the base sheet is cooled, and the coating film is formed via the base sheet. A method of cooling, a method of spraying cold air on the coating film, a method of passing the base sheet on which the coating film is formed, through a cooling zone adjusted to a room temperature below a desired temperature, and the like are used. Since the method of applying the coating film on the cooled substrate sheet can forcibly cool the coating film immediately after the coating film is applied on the substrate sheet, Mixing of a plurality of layers constituting a multilayer coating film can be prevented.

  In the cooling treatment step, the temperature at which the coating film is forcibly cooled is usually in the range of 0 ° C. to room temperature.

  After the cooling treatment, the coating film formed on the base sheet 2 is dried as necessary. In this way, the porous layer-forming coating film forms the porous layer 4, the dye-receiving layer forming coating film forms the dye-receiving layer 3, and the thermal transfer image-receiving sheet 1 is produced.

  In the manufacturing method of the thermal transfer image receiving sheet 1 described above, the case where the cooling treatment is performed after forming the coating film for forming the porous layer and the coating film for forming the dye receiving layer has been described as an example. Depending on the material constituting each layer of 1, the cooling treatment may be omitted by forming a coating film on the cooled base sheet 2.

  The thermal transfer image-receiving sheet of the present invention can be produced by a method of separately forming a porous layer and a dye-receiving layer on a substrate sheet, in addition to the production method by the slide coating method described above.

<Other structural examples of the thermal transfer image receiving sheet 1>
In the above, the case where the thermal transfer image receiving sheet 1 is formed by laminating the dye receiving layer 3 on the surface of the base sheet 2 via the porous layer 4 has been described in detail as an example. The transfer image sheet 1 may further include other layers as necessary.

  For example, as shown in FIG. 1B, the thermal transfer image-receiving sheet 1 not only has the dye-receiving layer 3 laminated on the surface of the substrate sheet 2 via the porous layer 4, but also the substrate sheet 2 and the porous sheet. An undercoat layer 6 may be formed between the porous layers 4, and a primer layer 5 may be formed between the porous layer 4 and the dye receiving layer 3.

(A) About the undercoat layer 6 The undercoat layer 6 is formed between the base sheet 2 and the porous layer 4 and has a function of improving the adhesion between the base sheet 2 and the porous layer 4. is there.

  The material constituting the undercoat layer 6 is not particularly limited as long as the adhesion between the base sheet 2 and the porous layer 4 can be improved to a desired level. Specific examples of the material constituting the undercoat layer 6 include a resin material that is dispersed and dissolved in an aqueous solvent that can be used as a binder when the porous layer 4 is formed. The undercoat layer 6 can be prepared by preparing a coating liquid with the material and solvent constituting the above-described undercoat layer 6, applying the coating liquid to a substrate sheet, and drying it. At this time, the solvent is appropriately selected from aqueous solvents used in the production of the porous layer 4.

(B) About the primer layer 5 The primer layer 5 is formed between the porous layer 4 and the dye receiving layer 3, and has a function of improving the adhesion between the porous layer 4 and the dye receiving layer 3 (suppressing separation). It is what you have.

  The material constituting the primer layer 5 is not particularly limited as long as the adhesion between the porous layer 4 and the dye receiving layer 3 can be improved to a desired level. Specifically, the material constituting the primer layer 5 is a resin material that is dispersed and dissolved in an aqueous solvent that can be used as a binder when forming the porous layer 4, as in the case of the undercoat layer 6. be able to. The primer layer 5 can be prepared by preparing a coating liquid with the material and solvent constituting the primer layer 5 and applying the coating liquid to a base sheet and drying it. At this time, the solvent is appropriately selected from an oil-based solvent and an aqueous solvent used in the production of the dye-receiving layer 3.

  For the undercoat layer 6 and the primer layer 5 of the thermal transfer image receiving sheet 1 as described above, a cooling gelling agent is contained in at least the binder of the undercoat layer 6. However, in terms of enabling the thermal transfer image-receiving sheet 1 to be produced effectively by the simultaneous multilayer coating method, it is preferable that the binder includes a cooling gelling agent in both layers of the undercoat layer 6 and the primer layer 5. . In this case, a cooling gelling agent is added to the coating liquid (coating liquid for forming the undercoat layer) for forming the coating film (coating film for forming the undercoat layer) that is to form the undercoat layer 6. Is included. In addition, the primer layer 5 is cooled to a coating liquid (primer layer forming coating liquid) for forming a coating film (primer layer forming coating film) scheduled to form the primer layer 5. A gelling agent is contained, and an aqueous solvent is selected as the solvent.

  When a cooling gelling agent is contained in the primer layer forming coating solution, a porous layer forming coating film and a dye acceptor are formed on the base sheet 2 when the thermal transfer image receiving sheet 1 is produced by the simultaneous multilayer coating method. When the layer forming coating film is formed simultaneously, the undercoat layer forming coating liquid and / or the primer layer forming coating liquid are applied at the same time, and the undercoat layer forming coating film and / or Or it becomes possible to form easily the coating film for primer layer formation.

  The blending amount of the cooling gelling agent blended in the undercoat layer forming coating solution for constituting the undercoat layer 6 is desired for the undercoat layer forming coating solution used when the undercoat layer 6 is formed. If it is in the range which can provide the viscosity characteristic, it will not specifically limit. Specifically, the blending ratio of the cooling gelling agent in the undercoat layer forming coating solution is in the range of 1 to 100 parts by weight with respect to 100 parts by weight of the resin material constituting the undercoat layer 6. In particular, it is preferably in the range of 20-80, more preferably in the range of 25-75. When the content ratio of the cooling gelling agent is less than the above range, for example, when the undercoat layer forming coating solution is applied onto the base sheet 2, a coating solution for forming another layer It is because there is a possibility of mixing with. Moreover, when it exceeds the said range, when applying the said undercoat layer forming coating liquid on the said base material sheet 2, for example, it becomes because it becomes easy to produce a stripe, a nonuniformity, etc.

  When the primer layer 5 contains a cooling gelling agent, the amount of the cooling gelling agent blended in the primer layer forming coating solution is the amount of the cooling gelling agent blended in the undercoat layer forming coating solution. Similarly to the case, it is not particularly limited as long as the desired viscosity characteristics can be imparted to the primer layer forming coating solution used when forming the primer layer 5. Therefore, specifically, the blending ratio of the cooling gelling agent in the primer layer forming coating solution is the same as that in the preferred range of the blending amount of the cooling gelling agent blended in the undercoat layer forming coating solution. Based on the reason, it is preferably within the range of 1 to 100 parts by weight, particularly preferably within the range of 20 to 80, and more preferably 25 to 75, with respect to 100 parts by weight of the resin material constituting the primer layer 5. It is preferable to be within the range.

  When the undercoat layer 6 and the primer layer 5 contain a cooling gelling agent, the cooling gelling agent contained in the undercoating layer 6 and the cooling gelling agent contained in the primer layer 5 are the porous layer 4 and Those usable from the cooling gelling agent contained in the dye receiving layer 3 are appropriately selected and used.

  The undercoat layer 6 and the primer layer 5 may contain a nonionic silicone-based surfactant, a curing agent such as an isocyanate compound, a wetting material, a dispersant, and the like. The curing agent is particularly effective when, for example, a thermoplastic resin having active hydrogen is used as a resin material constituting the undercoat layer 6 or the primer layer 5.

  The thermal transfer image-receiving sheet 1 can be produced by a method of individually laminating each layer (undercoat layer 6, porous layer 4, primer layer 5, and dye-receiving layer 3), or by a simultaneous multilayer coating method. The pulling layer 6, the porous layer 4, the primer layer 5, and the dye receiving layer 3 can be produced by a method of laminating and forming simultaneously.

  As a method for producing the thermal transfer image-receiving sheet 1 by the simultaneous multilayer coating method, a method by a slide coating method is preferably employed. When the thermal transfer image-receiving sheet 1 is produced by this method, an undercoat layer-forming coating solution, a porous layer-forming coating solution, a primer layer-forming coating solution, 4 layers of coating film (undercoat layer forming coating film, porous layer forming coating film, primer layer forming coating liquid A receiving layer-forming coating film) is produced at the same time. At this time, the porous layer is formed by applying the porous layer forming coating liquid between the base sheet 2 and the receiving layer forming coating film prepared by applying the receiving layer forming coating liquid. The coating film for forming is prepared, and further, the coating film for forming the undercoat layer is prepared between the base sheet and the coating film for forming the porous layer, and the coating film for forming the porous layer and the receiving layer are formed. A primer layer-forming coating film is produced between the coating films. Next, each coating film formed on the base sheet 2 is cooled and dried as necessary to produce the thermal transfer image receiving sheet 1.

  In the above description, the thermal transfer image receiving sheet 1 having both the primer layer 5 and the undercoat layer 6 has been described. However, in the thermal transfer image receiving sheet 1 of the present invention, either one of the primer layer 5 and the undercoat layer 6 is present. It may be provided.

  The present invention will now be illustrated in more detail using examples.

Example 1.
First, the coating solution for forming the dye receiving layer and the coating solution for forming the porous layer were prepared as follows.
<Adjustment of coating solution>
(1) Coating Solution for Dye Receiving Layer Formation In preparing a coating solution for forming a dye receiving layer, first, a resin composition A having a composition as shown in Table 1 below was prepared. In preparing the resin composition A, as a resin material, a vinyl chloride resin (manufactured by Nissin Chemical Industry Co., Ltd .; Vinyblan 900) and as an additive (in Table 1, additives 1 to 3), a gelling agent (Nitta Gelatin Co., Ltd.) RR), a polyether-modified silicone compound (manufactured by Shin-Etsu Chemical Co., Ltd .; KF615A), and a surfactant (manufactured by Nissin Chemical Industry Co., Ltd .; Surfynol 440) were used. In Table 1, the compounding amount (parts by weight) indicates parts by weight of solid content. And this resin composition A was diluted with water so that the whole solid content might be 30%, and the coating liquid for dye receiving layer formation was adjusted.

(Table 1)

(2) Coating liquid for forming porous layer In preparing a coating liquid for forming a porous layer, first, a resin composition B having a composition as shown in Table 2 below (in Table 2, composition B-1) To B-2) were adjusted. In preparing the resin composition B, “Rohm and Haas Co., Ltd .; HP-91” was used as the hollow particles, and “Shinfin Chemical Co., Ltd .; Surfinol 440” was used as the surfactant. As for the binder, as shown in the column of Example 1 in Table 3, as a resin material exhibiting rubber elasticity, MBR (manufactured by Dainippon Ink & Chemicals, Inc .; DM820, glass transition temperature (Tg); -30 The cooling gelling agent used was “Nitta Gelatin Co., Ltd .; CLW (jelly strength 309)” (the same applies to the gelatin in the column of Example 2 and Comparative Examples 1 to 4). In Table 2, the compounding amount (parts by weight) indicates parts by weight of solid content. And this resin composition B (B-1, B-2) was diluted with water so that the whole solid content might be 20%, and the coating liquid for porous layer formation was adjusted.

(Table 2)

(Table 3)

  Using the coating liquid adjusted as described above, a thermal transfer image receiving sheet was prepared as follows.

  Using RC paper (resin coated paper) (STF-150, manufactured by Mitsubishi Paper Industries Co., Ltd.) as the base sheet, the porous layer forming coating solution and the dye receiving layer forming coating solution are heated to 50 ° C. and slide coated. The coating liquid for forming a porous layer and the coating liquid for forming a dye receiving layer are applied so as to overlap each other by using the method, and the coating film for forming the porous layer and the dye overlapping in the thickness direction of the base sheet A two-layer coating film called a receiving layer-forming coating film was produced simultaneously.

  Furthermore, the base material sheet which produced the coating film of 2 layers was cooled at 5 degreeC for 1 minute, and those 2 layers were gelatinized. The two gelled layers were dried at 50 ° C. for 5 minutes. As a result, the coating film for forming the porous layer and the coating film for forming the dye receiving layer formed the porous layer and the dye receiving layer, respectively, and the porous layer and the dye receiving layer were simultaneously formed on the base sheet. Thus, the thermal transfer image receiving sheet 1 having a configuration in which the receiving layer was laminated on the base sheet surface via the porous layer was obtained. In the thermal transfer image-receiving sheet 1, the thicknesses of the porous layer and the dye-receiving layer were 30 μm and 5 μm, respectively.

  Using the obtained thermal transfer image-receiving sheet, a test was conducted on “roughness” of the thermal transfer image-receiving sheet as follows, and the test results were evaluated.

  The “roughness” of the thermal transfer image-receiving sheet was measured as follows for “roughness after storage processing” and “roughness before storage processing”.

"Roughness after storage process"
First, the thermal transfer image-receiving sheet was stored for 96 hours in an atmosphere of 60 ° C. and humidity of 10% or less (storage process). After the storage process, a “printing test” was performed using a thermal transfer image receiving sheet. This printing test was carried out by printing a predetermined image by the sublimation thermal transfer method on the obtained thermal transfer image receiving sheet. At this time, an image divided into 18 steps of black is used as a predetermined image to be printed, and combined with a dedicated thermal transfer sheet for ALTECH ADS, model: MEGAPIXEL III printer, for printing by the sublimation thermal transfer method. Then, thermal transfer recording was performed under the following conditions, and roughness was evaluated under the following conditions. However, the recording conditions were as follows.

(Recording conditions)
Thermal head; F-3598 (manufactured by Toshiba Hokuto Electronics Corporation)
Printing pressure: 5kg
Heating element average resistance value: 5186 (Ω)
Main scanning direction printing density; 300 dpi
Sub-scanning direction print density; 300 dpi
Applied power: 0.16 W / dot
Printing (recording) speed; 4.23 cm / sec.
Printing width: 150mm

  After an image divided into 18 black steps is formed on the thermal transfer image-receiving sheet, the white spots in the highlight portions are visually evaluated to obtain a uniform black 18 step image with no white missing portions. When it was observed, “good” was evaluated, and when a slightly white spot was observed, it was evaluated as “bad”.

"Roughness before saving"
Using the thermal transfer image-receiving sheet, a printing test was performed without performing the storage process, and the result of the printing test was evaluated based on the same criteria as the evaluation of “roughness after the storage process”.

  Table 4 shows the test results for “roughness” using the thermal transfer image-receiving sheet of Example 1.

  Table 4 below shows the evaluation results of “sensitivity” and “roughness after storage processing” of the thermal transfer image-receiving sheet. It was confirmed that the occurrence of “white spots” was effectively suppressed regardless of before and after the storage process, and that the thermal transfer image-receiving sheet was kept from being stiff and rough.

Example 2 and Comparative Examples 1 to 4
The resin composition B used when carrying out the step of forming the porous layer in Example 1 is shown in the columns of Example 2 and Comparative Examples 1 to 4 in Table 3, except that the Example In the same manner as in No. 1, a thermal transfer image receiving sheet was produced. Using the obtained thermal transfer image-receiving sheet, a test for “roughness” was conducted in the same manner as in Example 1, and the test results were evaluated. The results are shown in Table 4.

(Table 4)

(A) is a schematic cross-sectional view showing one example of the thermal transfer image-receiving sheet of the present invention. (B) is a schematic cross-sectional view showing one of the other examples of the thermal transfer image-receiving sheet of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal transfer image receiving sheet 2 Base material sheet 3 Dye receiving layer 4 Porous layer 5 Primer layer 6 Undercoat layer

Claims (5)

A thermal transfer image-receiving sheet obtained by laminating a dye-receiving layer via a porous layer on the surface of a substrate sheet,
The porous layer comprises a binder and hollow particles,
A binder is a thermal transfer image-receiving sheet, comprising a resin material exhibiting rubber elasticity and a gelling agent.   The thermal transfer image receiving sheet according to claim 1, wherein the binder includes a resin material exhibiting rubber elasticity having a glass transition temperature (Tg) of 0 ° C. or less.   The thermal transfer image receiving sheet according to claim 1 or 2, wherein the binder includes a resin material exhibiting rubber elasticity made of styrene butadiene rubber (SBR) or methyl methacrylate butadiene rubber (MBR).   The thermal transfer image-receiving sheet according to any one of claims 1 to 3, wherein a resin material exhibiting rubber elasticity in the binder is blended in a range of 10 wt% to 30 wt%.   5. The porous layer according to claim 1, wherein the porous layer contains a binder and hollow particles at a blending ratio of binder: blending amount of hollow particles = 40 to 10 parts by weight: 60 to 90 parts by weight. Thermal transfer image receiving sheet.

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