JP2007098693A - Thermal transfer image receiving sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer image receiving sheet which is excellent in sensitivity, can obtain an image with a decreased roughness on its highlight part, has smoothness, and is excellent in glossy feeling. <P>SOLUTION: The thermal transfer image receiving sheet is prepared by laminating a hollow particle (a) layer consisting of a hollow particle (a), a hollow particle (b) layer consisting of a hollow particle (b), and a receiving layer on a substrate in this order. The thermal transfer image receiving sheet is characterized in that the substrate sheet is prepared by laminating a resin layer on both faces of the base paper, the hollow particle (a) layer has a thickness of 10-20 μm, the hollow particle (a) has a volume mean particle diameter of 3-10 μm, and the hollow particle (b) has a volume mean particle diameter of 0.5-1 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a thermal transfer image receiving sheet.

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 full-color image is formed by superimposing a thermal transfer image-receiving sheet provided with a dye receiving layer on a sheet. Since this method uses a thermal diffusion dye as the color material, the density and gradation can be freely adjusted in dot units, and a full color image as it is on the original can be clearly displayed on the image receiving sheet. It is applied to color image formation for computers. The image is of a high quality comparable to a silver salt photograph.

As a thermal transfer image receiving sheet, a sheet in which a porous layer composed of hollow particles and a binder resin is provided between a base sheet and a receiving layer for the purpose of imparting heat resistance and cushioning properties has been proposed (for example, patents). Reference 1). Regarding this porous layer, it is described that if there is too much binder resin, the binder resin fills the voids and loses heat insulation and cushioning properties, but a certain amount of thickness is required to obtain heat insulation and cushioning properties. There was a problem.

As a thermal transfer image-receiving sheet provided with a layer containing hollow particles, a sheet-like cellulose core layer, a porous resin layer (porous layer), a laminate layer of a thermoplastic resin, and a dye-dyed receiving layer are sequentially provided. Has been proposed (see, for example, Patent Document 2). This thermal transfer image-receiving sheet has a porous layer density of 0.05 to 0.5 g / cm ³ for the purpose of obtaining high recording sensitivity and recording density. The porous layer contains bubbles by a stirring method. There is a problem that the resin and a thermally expandable resin forming an excessive hollow are used, and the smoothness is not sufficient. Furthermore, this thermal transfer image-receiving sheet has a problem that the porous structure of the porous layer is deformed and crushed by heat during the formation of the laminate layer, and the effect of improving sensitivity and image quality cannot be obtained sufficiently.

As a thermal transfer image receiving sheet provided with a layer containing hollow particles, a thermal transfer receiving sheet in which an intermediate layer containing hollow particles and an image receiving layer are sequentially formed on at least one surface of a sheet-like support has been proposed (for example, (See Patent Document 3). In this thermal transfer image-receiving sheet, the intermediate layer is composed of a first intermediate layer having a large average particle diameter in the lower layer and a second intermediate layer having a small average particle diameter in the upper layer. The problem is that it is formed with a thickness and is expensive, and when the first intermediate layer is made thin, not only the deterioration of sensitivity due to the decrease in heat insulation and cushioning properties, but also the deterioration of the image due to the decrease in surface smoothness, the glossiness There was a problem of loss of sensation.
JP 2002-212890 A ([0016], [0017]) JP 2000-272259 A (pages 1 to 6) JP 2004-345289 A ([Claim 1], [0026])

In view of the above situation, an object of the present invention is to provide a thermal transfer image-receiving sheet that is excellent in sensitivity, can obtain an image with reduced roughness of highlight portions, and has smoothness and glossiness. It is in.

The present invention relates to a thermal transfer image receiving sheet obtained by laminating a hollow particle (a) layer comprising hollow particles (a), a hollow particle (b) layer comprising hollow particles (b) and a receiving layer in this order on a substrate sheet. The base sheet is formed by laminating resin layers on both surfaces of a base paper, the hollow particle (a) layer has a thickness of 10 to 20 μm, and the hollow particle (a) has a volume of An average particle diameter is 3-10 micrometers, The said hollow particle (b) is a volume average particle diameter is 0.5-1 micrometer, It is a thermal transfer image receiving sheet characterized by the above-mentioned.
The present invention is described in detail below.

(Substrate sheet)
The thermal transfer image receiving sheet of the present invention is obtained by laminating a hollow particle (a) layer, a hollow particle (b) layer and a receiving layer in this order on a base sheet.
The base sheet is a sheet in which a resin layer is laminated on both sides of a base paper (in this specification, sometimes referred to as “resin-coated paper”).
The base sheet has a role of holding the receiving layer and heat is applied during thermal transfer. Therefore, the base sheet preferably has a mechanical strength that does not hinder handling even in a heated state.

Examples of the base paper constituting the base paper include natural pulp, synthetic pulp, and pulp paper made from a mixture thereof. Among these, paper mainly composed of wood pulp is preferable.
The base paper may be subjected to a conventionally known process such as a calendar process, which will be described later, as necessary.

The base paper preferably has a high smoothness, more preferably has a Beck smoothness of 1000 seconds or more, and more preferably has a Beck smoothness of 5000 seconds or more.
In this specification, the Beck smoothness is a value measured according to JIS P8119 using a Digibeck smoothness tester (manufactured by Toyo Seiki Co., Ltd.).
The base paper preferably has a thickness of 10 to 400 μm, and more preferably 50 to 200 μm.

The base paper can be produced by a known method, but a base paper that is calendered is preferable. When a base paper that is 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 calendar process is not particularly limited, and for example, a machine calendar, a super calendar, a thermal calendar, or the like can be used.

In the substrate sheet, the resin layer may be formed on the same surface by only one layer, or may be formed by two or more layers.
When two or more resin layers are laminated, each resin layer may be made of the same resin or may be made of different types of resins.

Examples of the resin for forming the resin layer include resins having a small neck-in and good drawdown properties, such as polyolefin resins, polystyrene resins, vinyl resins, polyester resins, ionomer resins, nylon, and polyurethane. Although mentioned, polyolefin resin is preferable at the point from which the film excellent in water resistance, intensity | strength, glossiness, etc. is obtained.
Examples of the polyolefin resin include high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, polybutene, and polypentene, among which high-density polyethylene, medium-density polyethylene, low-density polyethylene, and polypropylene are preferable. Polypropylene is more preferred.
The resin may contain an additive such as a modifier to improve adhesiveness. Examples of the modifying agent include olefin copolymers such as Tuffmer A (manufactured by Mitsui Chemicals).

The resin layer may be a film or sheet obtained by mixing one or more of the above resins, or a film or sheet formed by adding a pigment, a filler, or the like to the above resin. May be.
The substrate sheet can be produced by a known lamination method such as dry lamination, wet lamination, or extrusion. Each of the resin layers can be appropriately subjected to primer treatment or corona discharge treatment on the surface for the purpose of improving interlayer adhesion.

The thermal transfer image-receiving sheet of the present invention is excellent in smoothness, water resistance, curling property, strain, strength and the like by using a resin-coated paper as a base material sheet. ) Since it is possible to prevent moisture contained in the layer coating liquid from penetrating into the paper substrate, an image free from density unevenness and white spots can be created.

In the thermal transfer image receiving sheet of the present invention, the total thickness of the base sheet is usually 50 to 1000 μm, preferably 50 to 300 μm, and can be appropriately selected from the range.
The said base material sheet WHEREIN: It is preferable that the thickness of the said resin layer is 10-40 micrometers, and it is more preferable that it is 10-30 micrometers.
In addition, the thickness of the said resin layer means the total thickness of this two or more layers, when the resin layer is two or more layers.

(Hollow particle (a) layer)
In the thermal transfer image receiving sheet of the present invention, the hollow particle (a) layer is provided at least on the same side as the receiving layer of the base sheet. The hollow particle (a) layer can be directly laminated on the substrate sheet.

The hollow particles (a) preferably have a hollow ratio of 60% or more, more preferably 68% or more, still more preferably 80% or more, and within the above range, 85% or less. It may be. When the hollowness is less than 60%, the thermal transfer image-receiving sheet may not be sufficiently imparted with cushioning properties and heat insulation properties. If it exceeds 85%, the heat resistance strength of the hollow particles is lowered, and the cushioning property, heat insulating property, etc. of the thermal transfer image-receiving sheet are not sufficiently exhibited and the sensitivity may be lowered. In this specification, the hollow ratio indicates the proportion of the volume of air in the hollow particles.

The hollow particles (a) have a volume average particle size of 3 to 10 μm, preferably 3 to 7 μm. If it is less than 3 μm, the hollowness ratio may not be within the above range, the cost may be increased, and the heat insulation and cushioning properties may be difficult to be exhibited and the sensitivity may be lowered. If it exceeds 10 μm, the resulting sheet may have irregularities derived from particles in the image.
In the thermal transfer receiving sheet of the present invention, since the hollow particles (a) have a volume average particle size within the above range, the cushioning property is particularly excellent, and the sensitivity is good with little unevenness and white spots.
In the present specification, the volume average particle diameter is measured based on a laser diffraction particle size distribution measurement method (microtrack method).

The hollow particles (a) are blended to impart cushioning properties, heat insulation properties, etc. to the thermal transfer image-receiving sheet and to improve the sensitivity.
The hollow particles (a) are preferably foamed particles that are foamed before forming the hollow particle (a) layer. When the hollow particles (a) are the already expanded particles, a relatively large volume average particle diameter as in the above range can be easily achieved.

The foamed particles include, for example, a hollow part formed by expanding a gas such as butane gas encapsulated in a thermoplastic polymer, and a shell part made of the thermoplastic polymer and enclosing the hollow part. Organic hollow particles are preferred.
Examples of the thermoplastic polymer include homopolymers or copolymers such as vinylidene chloride, acrylonitrile, styrene, (meth) acrylic acid, (meth) acrylic acid ester, etc., but polyacrylonitrile, acrylic acid ester, etc. Etc. are preferred.

The hollow particle (a) layer preferably contains the hollow particles (a) in an amount of 60 to 80% by mass. When the amount is less than 60% by mass, the cushioning property, the heat insulating property, and the like may not be sufficient. .
The content ratio of the hollow particles (a) is more preferably 65 to 75% by mass.

The hollow particle (a) layer generally has a structure in which the hollow particles (a) are supported on a binder resin.
In the present invention, the binder resin constituting the hollow particle (a) layer has effects such as imparting adhesiveness to the base sheet and the hollow particle (b) layer and preventing bleeding.
As the binder resin, known resins can be appropriately selected, and examples thereof include urethane resins; ester resins; vinyl resins such as vinyl acetate and polyvinyl alcohol; acrylic resins; cellulose resins; . The resin may be dissolved in water, dispersed, or may form an emulsion.
The binder resin may be a single type or a mixture of two or more types of binder resins.
The binder resin is preferably a vinyl resin or a urethane resin from the viewpoint of adhesiveness to the base sheet or the hollow particle (b) layer.

In addition to the hollow particles (a) and the binder resin, the hollow particle (a) layer is a known stabilizer, antistatic agent, ultraviolet absorber, fluorescent substance as long as the properties such as heat insulation and cushioning properties are not impaired. An additive such as a brightening agent, a processing aid, and a plasticizer may be appropriately blended.

The hollow particle (a) layer has a thickness (film thickness after drying) of 10 to 20 μm. If it is less than 10 μm, the heat insulating properties and cushioning properties tend to be insufficient. If it exceeds 20 μm, the cost becomes high.
The upper limit of the thickness of the hollow particle (a) layer is preferably 18 μm.

The hollow particle (a) layer preferably has a density of 0.1 to 0.3 g / cm ³ . When the density is less than 0.1 g / cm ³ , the highlight portion of the obtained printed matter may be rough, and when it exceeds 0.3 g / cm ³ , the sensitivity and cushioning properties are insufficient. There is.
As for the said hollow particle (a) layer, it is more preferable that the said density is 0.2-0.3 g / cm < ³ >.
The hollow particle (a) layer preferably has a relatively low density as in the above range, but the binder resin does not fill the voids between the hollow particles (a) and embeds the air. It is thought that the structure is formed. With this structure, it is considered that heat insulation and cushioning properties are extremely excellent, and good sensitivity can be obtained.
In this specification, the said density is the value calculated | required based on the thickness change before and behind drying at the time of apply | coating and drying a hollow particle (a) layer coating liquid, and the weight of the hollow particle (a) layer after drying. is there.

The hollow particle (a) layer is prepared by preparing a coating solution for a hollow particle (a) layer obtained by dissolving or dispersing the above-described binder resin and hollow particles, and an additive to be added as desired in an aqueous medium. It can laminate | stack by apply | coating the coating liquid for hollow particle (a) layers on a base material sheet, and drying.

Examples of the aqueous medium in the coating solution for the hollow particle (a) layer include water; alcohols such as ethanol and propanol; and mixtures thereof.

The hollow particle (a) layer coating solution can be applied by a general method such as roll coating, bar coating, gravure coating, gravure reverse coating, comma coating, die coating, and lip coating.
The hollow particle (a) layer coating liquid is preferably applied so that the hollow particle (a) layer has a thickness within the above-described range.
In the coating of the hollow particle (a) layer, drying is preferably performed at a temperature of 50 to 150 ° C., although it varies depending on the composition of the coating solution used.
In order to smooth the surface of the layer after the coating of the hollow particle (a) layer, a known resin surface modification such as primer treatment may be performed.

(Hollow particle (b) layer)
In the thermal transfer image receiving sheet of the present invention, the hollow particle (b) layer is laminated on the hollow particle (a) layer.
The hollow particle (b) layer imparts gloss to the obtained thermal transfer image-receiving sheet, maintains sensitivity, prevents bleeding, and reduces the occurrence of roughness in the highlight portion of the resulting printed product. It is to be provided.

The hollow particle (b) layer generally has a structure in which the hollow particles (b) are supported on a binder resin.
The said hollow particle (b) can show the effect which maintains the maximum sensitivity highly in the obtained thermal transfer image receiving sheet, and reduces the roughness of the highlight part of the obtained printed matter.

The hollow particles (b) may be either expanded particles or unexpanded particles. For example, organic hollow particles and inorganic hollow glass bodies can be used as the hollow particles.
The organic hollow particles used as the hollow particles (b) may have, for example, the thermoplastic polymer as a shell, and among them, those having an acrylic polymer as a shell are preferable.
When the hollow particles (b) are expanded particles, they may be either closed foam or continuous foam.

The hollow ratio in the hollow particles (b) is generally smaller than the hollow particles (a) in the hollow particle (a) layer, and preferably 40% or more and less than 60%.
The hollow particles (b) have a volume average particle size of usually 0.5 to 1 μm, preferably 0.7 to 1 μm. If it is less than 0.5 μm, the cost may increase. When the volume average particle diameter exceeds 1 μm, there may be a case in which the image is smeared in the image in the obtained sheet.

The content ratio of the hollow particles (b) in the hollow particle (b) layer is preferably 1% by mass or more and 60% by mass or less, and more preferably 15 to 50% by mass. When the amount is less than 1% by mass, the maximum sensitivity may not be sufficiently maintained, and the highlight roughness of the printed matter may not be sufficiently eliminated. If it exceeds 60% by mass, the interlaminar adhesion may be lowered.

The binder resin in the hollow particle (b) layer has effects such as improving glossiness of the obtained sheet, imparting interlayer adhesion, and preventing bleeding.
The binder resin can be appropriately selected from known ones, and examples thereof include those similar to those exemplified for the hollow particle (a) layer.

In addition to the hollow particles (b) and the binder resin, the hollow particle (b) layer may be formed by appropriately blending the above-mentioned known additives as long as the properties of the layer are not impaired. .

The hollow particle (b) layer preferably has a thickness (film thickness after drying) of 0.5 to 2 μm, and more preferably 0.8 to 1 μm. When the thickness is less than 0.5 μm, a desired effect may not be obtained, and when it exceeds 2 μm, sufficient sensitivity may not be obtained.
Since the thermal transfer image-receiving sheet of the present invention has a hollow particle (a) layer and a hollow particle (b) layer, it has smoothness, heat insulation, sensitivity, wood grain unevenness and blurring are less likely to occur, It can be manufactured at low cost.

The hollow particle (b) layer prepares a coating solution for a hollow particle (b) layer in which the binder resin and the hollow particle (b) described above and an additive to be added as desired are dissolved or dispersed in an aqueous medium, It can laminate | stack by apply | coating this coating liquid for hollow particle (b) layers on a hollow particle (a) layer, and drying.

Examples of the aqueous medium in the coating liquid for the hollow particle (b) layer include the same ones as the coating liquid for the hollow particle (a) layer.

The hollow particle (b) layer coating solution is generally applied so that the thickness after drying is in the above range. Application | coating in the lamination | stacking of the said hollow particle (b) layer, drying, etc. can be performed similarly to the above-mentioned hollow particle (a) layer.

(Receptive layer)
In the thermal transfer image receiving sheet of the present invention, the receiving layer is formed by laminating on the hollow particle (b) layer.
The receiving layer is composed of a resin that easily dyes the dye and various additives such as a release agent to be added as desired.
Examples of the resin that is easily dyed include polyolefin resins such as polypropylene, halogenated resins such as polyvinyl chloride resin and polyvinylidene chloride, vinyl resins such as polyvinyl acetate and polyacrylate, and copolymers thereof. Polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resins, polyamide resins, copolymers of olefins such as ethylene and propylene and other vinyl monomers, ionomers, cellulose derivatives alone, or mixtures thereof Among them, polyester resin and vinyl resin are preferable, and vinyl chloride-vinyl acetate copolymer is more preferable.

A release agent can also be blended in the receiving layer in order to prevent thermal fusion with the thermal transfer sheet during image formation.
Examples of the release agent include known ones such as silicone oil, phosphate ester compounds, and fluorine compounds, but silicone oil is particularly preferable.
Examples of the 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, hydrogen-modified silicone oil, etc. Modified silicone oil is preferred.
The release agent is preferably added so as to be about 0.2 to 30 parts by mass with respect to 100 parts by mass of the resin.

The receptor layer is formed by appropriately blending known additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a pigment, an antistatic agent, a plasticizer, and a hot-melt material. Also good.

The receiving layer is prepared by, for example, preparing a receiving layer coating solution in which a resin that easily dyes the above-described dye, and a release agent and / or an additive compounded as necessary are dispersed in a solvent. It can laminate | stack by coating the coating liquid for layers on a hollow particle (b) layer.

The receiving layer coating solution usually has a solid content concentration of 5% by mass or more. If the solid content concentration is too high, the storage stability is lowered and the viscosity may be increased. Therefore, it is usually preferably 50% by mass or less.
Solvents for preparing the receiving layer coating solution include, for example, water; alcohols such as ethanol; mixed liquids of water and alcohols; aromatics such as toluene, xylene and chlorobenzene; acetone and methyl ethyl ketone. Ketones such as ethyl acetate and butyl acetate; ethers such as tetrahydrofuran and dioxane; chlorinated solvents such as chloroform and trichloroethylene; nitrogen-containing solvents such as dimethylformamide and N-methylpyrrolidone; dimethyl sulfoxide A mixture of these solvents; and the like.

Application | coating of the said coating liquid for receiving layers can be performed by the above-mentioned general method.
The receiving layer coating solution is preferably applied such that the receiving layer has an amount of 0.5 to 10 g / m ² after drying.
In the coating of the receptor layer, drying is preferably performed at a temperature of 50 to 150 ° C., although it varies depending on the composition of the coating solution used.
After applying the receptor layer, a known resin surface modification such as primer treatment may be performed to smooth the surface of the layer.

(Back layer)
The thermal transfer image-receiving sheet of the present invention has a back layer on the surface opposite to the receiving layer-forming side of the substrate sheet for the purpose of improving the mechanical transportability of the sheet, preventing curling, writing properties, preventing charging and the like. May be.
In the thermal transfer image-receiving sheet of the present invention, the back layer may be composed of only one layer, or may be composed of two or more layers having different compositions and the like. .

The said back surface layer can be formed from resin which forms the said hollow particle (a) layer, other well-known things.
When forming the back layer, for example, (1) In addition to the above-exemplified resins, etc., an appropriate amount of organic filler or inorganic filler is added, or (2) a resin having high lubricity, such as a polyolefin resin or a cellulose resin. When used, it is possible to obtain a thermal transfer image receiving sheet with improved transportability during printing.

When the back layer is formed, curling of the obtained thermal transfer image-receiving sheet can be prevented when a water-holding resin such as polyvinyl alcohol or polyethylene glycol is used as a main component.
When the back layer is formed, when fillers, pigments, and the like exemplified as additives in the above-described receiving layer are blended, writing property can be imparted to the resulting thermal transfer image-receiving sheet.

In order to obtain an antistatic function, the back layer is made by adding a conductive resin such as an acrylic resin and / or various antistatic agents such as fatty acid ester, sulfate ester, phosphate ester, and ethylene oxide adduct. There may be.
The amount of the antistatic agent used varies depending on the layer to which the antistatic agent is added, the antistatic agent used, and the like, but the surface electrical resistance value of the thermal transfer image-receiving sheet is 10 ¹³ in order to prevent paper feeding troubles. It is preferable to blend so as to be Ω / cm ² or less.

The said back surface layer can be laminated | stacked by a well-known method. The back layer is preferably used so that the coating amount of the coating solution is 0.01 to 3 g / m ² after drying.

(Image formation)
The method for forming an image on the image receiving surface of the thermal transfer image receiving sheet of the present invention is not particularly limited, and can be performed by a known thermal diffusion transfer method (sublimation thermal transfer method).
The thermal transfer sheet used for the image formation is not particularly limited. For example, a conventional thermal transfer sheet in which a dye layer containing a thermal diffusion dye (sublimation dye) is provided on a base sheet is used. Can do.
In particular, the thermal transfer sheet is preferably composed of a dye layer made of a polyacetal resin and a base sheet made of a polyester resin.

The thermal transfer image receiving sheet of the present invention may be formed by transferring a protective layer to the image forming surface after forming an image on the image receiving surface of the thermal transfer image receiving sheet.

The protective layer can be formed from a known protective layer forming resin such as a thermoplastic resin, a heat crosslinkable resin, or an ionizing radiation crosslinkable resin.
Examples of the thermoplastic resin include polyester resins, acrylic resins, polycarbonate resins, urethane resins, epoxy resins, phenoxy resins, and resins obtained by modifying these resins with silicone.
The protective layer may be formed by blending one or more thermoplastic resins, thermally crosslinkable resins, and ionizing radiation crosslinked resins.
In addition to the resin, the protective layer may be formed by appropriately blending the additives described for the receiving layer, such as an ultraviolet blocking resin, an ultraviolet absorber, a conductive resin, and a filler, as necessary. .

The protective layer may be composed of only one layer, or may be composed of two or more layers having different compositions and the like.
The protective layer may have an adhesive layer in order to improve transferability to the thermal transfer image-receiving sheet (printed material), adhesion, and the like.
Although the said contact bonding layer can be formed from a conventionally well-known thing, it is more preferable to form from a thermoplastic resin whose glass transition temperature (Tg) is 50-80 degreeC.
Examples of the thermoplastic resin include those having a glass transition temperature within the above range from polyester resin, vinyl chloride-vinyl acetate copolymer resin, acrylic resin, butyral resin, epoxy resin, polyamide resin, vinyl chloride resin, and the like. It is preferable to select. In terms of adhesiveness, the thermoplastic resin preferably has a smaller average molecular weight.
The said protective layer is 0.1-30 micrometers normally in the whole layer, Preferably it can be set as the thickness of 0.5-5 micrometers.

Since the thermal transfer image-receiving sheet of the present invention has the above-described configuration, it is possible to obtain an image that is excellent in sensitivity, glossiness, smoothness, has less blurring, and has reduced white spots and roughness in highlight portions.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited only to these Examples and Comparative Examples.
In addition, in a sentence, a part or% is the mass reference | standard of solid content except the thing regarding a solvent.

Example 1
1. Preparation of base sheet RC base paper (thickness: 172 μm, basis weight: 175 g / m ² , manufactured by Mitsubishi Paper Industries Co., Ltd.) was smoothed with a super calendar to a Beck smoothness of 2000 seconds, and then a polypropylene resin (product name: Sun Allomer PHA03A (manufactured by Sun Allomer Co., Ltd.) was dried by an extrusion coater and laminated to a thickness of 22 μm.
Furthermore, on the other side, high density polyethylene resin (product name: J-Rex KH578A, manufactured by Nippon Polyolefin Co., Ltd.) 100 parts and olefin copolymer (product name: Tuffmer A-4085, manufactured by Mitsui Chemicals) 18 parts are blended. The resulting resin coating solution (i) is laminated by drying with an extrusion coater so as to have a thickness of 14 μm, and a polypropylene resin (product name: Sun Allomer PHA03A, manufactured by Sun Allomer Co., Ltd.) is dried on the obtained resin layer after drying with an extrusion coater. A substrate sheet was prepared by laminating to a thickness of 19 μm.

2. Formation of hollow particle (a) layer (1) A coating solution (I) for hollow particle (a) having the following composition is applied onto the above base sheet so that the thickness is 13 μm after drying by gravure coating. Then, it was dried (110 ° C., 1 minute) to form a hollow particle (a) layer having a density of 0.28 g / cm ³ .
In addition, the said density is the value calculated | required based on the thickness change before and behind drying at the time of apply | coating and drying the said hollow particle (a) layer coating liquid, and the weight of the hollow particle (a) layer after drying.
(Hollow particle (a) layer coating liquid (I) composition)
・ Acrylic hollow particles (foamed particles, hollow ratio 80%, volume average particle size 3.2 μm, manufactured by Matsumoto Yushi Co., Ltd.) 75 parts ・ Polyvinyl alcohol (product name: PVA220, manufactured by Kuraray Co., Ltd.) 25 parts ・ Water 900 parts 2 . Formation of the hollow particle (b) layer On the hollow particle (a) layer, the hollow particle (b) layer coating liquid (I) having the following composition is dried by gravure coating so as to be 1.2 g / m ² after drying. It apply | coated and dried (110 degreeC, 1 minute), and the hollow particle (b) layer was formed.
(Hollow particle (b) layer coating liquid (I) composition)
・ Acrylic hollow particles (Product name: Ropaque HP-1055, non-crosslinked type, hollow ratio 55%, hollow particle diameter 1.0 μm, solid content 26.50%, manufactured by Rohm and Haas) 50 parts ・ Polyvinyl alcohol (Product Name: PVA217, manufactured by Kuraray Co., Ltd.) 50 parts / water 900 parts

3. Preparation of Receiving Layer On the hollow particle (b) layer, a receiving layer coating liquid (I) having the following composition was dried and applied by gravure coating so that the amount was 4.0 g / m ² and dried ( 110 ° C. for 1 minute) to obtain the thermal transfer image-receiving sheet of the present invention.
(Coating fluid for receiving layer (I) composition)
-120 parts of vinyl chloride-vinyl acetate copolymer (Solvine C; manufactured by Nisshin Chemical Co., Ltd.)-12 parts of epoxy-modified silicone (X22-3000T; manufactured by Shin-Etsu Chemical Co., Ltd.)-Phenyl-modified silicone (X24-510; Shin-Etsu Chemical Co., Ltd.) 6 parts) Methyl ethyl ketone / toluene = 8/2 (parts by mass) 690 parts

Example 2
A thermal transfer image-receiving sheet was prepared in the same manner as in Example 1 except that the hollow particle (a) layer coating liquid (II) having the following composition was used instead of the hollow particle (a) layer coating liquid (I). Obtained. The density of the hollow particle (a) layer in this example was 0.20 g / cm ³ .
(Hollow particle (a) layer coating liquid (II) composition)
・ Acrylic hollow particles (foamed particles, hollow ratio 80%, volume average particle size 6.6 μm, manufactured by Matsumoto Yushi Co., Ltd.) 75 parts ・ Polyvinyl alcohol (product name: PVA220, manufactured by Kuraray Co., Ltd.) 25 parts ・ Water 900 parts

Example 3
Instead of the hollow particle (a) layer coating liquid (I), a hollow particle (a) layer coating liquid (III) having the following composition was used, except that the thickness was 18 μm after drying. In the same manner as in Example 1, a thermal transfer image receiving sheet was obtained. The density of the hollow particle (a) layer in this example was 0.15 g / cm ³ .
(Hollow particle (a) layer coating liquid (III) composition)
・ Acrylic hollow particles (foamed particles, hollow ratio 80%, volume average particle size 10 μm, manufactured by Matsumoto Yushi Co., Ltd.) 75 parts ・ Polyvinyl alcohol (product name: PVA220, manufactured by Kuraray Co., Ltd.) 25 parts ・ Water 900 parts

Example 4
Instead of the hollow particle (a) layer coating solution (I), a hollow particle (a) layer coating solution (IV) having the following composition was used, except that the thickness was 10 μm after drying. In the same manner as in Example 1, a thermal transfer image receiving sheet was obtained. The density of the hollow particle (a) layer in this example was 0.15 g / cm ³ .
(Hollow particle (a) layer coating liquid (IV) composition)
・ Acrylic hollow particles (foamed particles, hollow ratio 80%, volume average particle size 10 μm, manufactured by Matsumoto Yushi Co., Ltd.) 75 parts ・ Polyvinyl alcohol (product name: PVA220, manufactured by Kuraray Co., Ltd.) 25 parts ・ Water 900 parts

Comparative Example 1
In place of the hollow particle (a) layer coating liquid (I), a hollow particle (a) layer coating liquid (V) having the following composition was used, except that the thickness after drying was 40 μm. Obtained a thermal transfer image receiving sheet in the same manner as in Example 1. In addition, the density of the hollow particle (a) layer in this comparative example was 0.10 g / cm ³ .
(Hollow particle (a) layer coating liquid (V) composition)
・ Acrylic hollow particles (foamed particles, hollow ratio 80%, volume average particle size 15 μm, manufactured by Matsumoto Yushi Co., Ltd.) 75 parts ・ Polyvinyl alcohol (product name: PVA220, manufactured by Kuraray Co., Ltd.) 25 parts ・ Water 900 parts

Comparative Example 2
A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the hollow particle (a) layer coating solution (I) was applied so that the thickness after drying was 5 μm. The density of the hollow particle (a) layer in this comparative example was the same as that in Example 1 (0.28 g / cm ³ ).

Comparative Example 3
A thermal transfer image-receiving sheet was prepared in the same manner as in Example 1 except that the hollow particle (a) layer coating liquid (VI) having the following composition was used instead of the hollow particle (a) layer coating liquid (I). Obtained. The density of the hollow particle (a) layer in this comparative example was 0.75 g / cm ³ .
(Hollow particle (a) layer coating liquid (VI) composition)
・ Acrylic hollow particles (Product name: Ropaque HP-1055, non-crosslinked type, hollow ratio 55%, hollow particle diameter 1.0 μm, solid content 26.50%, manufactured by Rohm and Haas) 75 parts ・ Polyvinyl alcohol (Product Name: PVA220, manufactured by Kuraray Co., Ltd.) 25 parts / water 900 parts

Comparative Example 4
A thermal transfer image-receiving sheet was prepared in the same manner as in Example 1 except that the hollow particle (b) layer coating liquid (II) having the following composition was used instead of the hollow particle (b) layer coating liquid (I). Obtained.
(Hollow particle (b) layer coating liquid (II) composition)
・ Polyvinyl alcohol (Product name: PVA217, manufactured by Kuraray Co., Ltd.) 50 parts ・ Water 900 parts

Test Example The thermal transfer image-receiving sheet obtained from each example and each comparative example was evaluated by the following method.
<Evaluation method>
1. Measurement of dyeing property (sensitivity) (1) Yellow (Y), Magellan (M) using sublimation transfer printer CP-200 (manufactured by Canon) and thermal transfer sheet for sublimation transfer printer CP-200 (manufactured by Canon) ), Cyan (C), and protective layer in this order, a gradation image was formed under the following conditions.
(Print printing conditions)
Gradation printing: The duty ratio of each divided pulse is fixed at 40%, and the number of pulses per line period is increased by 17 from 0 to 255, thereby controlling 16 gradations from 1 to 16 steps. A gradation pattern consisting of gradation was printed. The printing environment was set to 25 ° C. and humidity 40%.
Transfer of protective layer: The number of pulses per line period was fixed at 210, solid printing was performed, and the protective layer was transferred to the entire print surface.

(2) About each printed matter, the maximum reflection density (measurement range: 3 Bk) was measured using the chromaticity meter (Macbeth densitometer RD-918; Macbeth company make).
Using the sensitivity of the printed matter obtained in Example 1 as a reference (5 points), the one that is better than the reference is 6 points or 7 points, and the one that is inferior to the reference is 1 in descending order of sensitivity. Points, 2, 3 or 4 points were used.

2. Appearance (smoothness)
1. The degree of unevenness was evaluated visually with respect to the printed matter prepared at the time of measuring the dyeing property (sensitivity). Using the degree of unevenness of the printed material obtained in Example 2 as a reference (5 points), 6 points with less unevenness than the reference, 3 points or 4 points with more unevenness in order from the more unevenness It was.

3. White spots The printed matter produced at the time of measuring the dyeing property (sensitivity) was visually evaluated for white spots.
Using the sensitivity of the printed matter obtained in Example 1 as a reference (5 points), 6 or 7 points were better than the reference, and 4 points were inferior to the reference.
4). The overall evaluation sensitivity and the external evaluation score were 5 or more, and the others were evaluated as x.
Table 1 shows the results.

It was found that the thermal transfer image-receiving sheets of Examples 1 to 4 were excellent in both sensitivity and appearance. In particular, since the thermal transfer image-receiving sheets of Example 2 and Example 3 had good results for sensitivity and white spots, the volume average particle diameter of the hollow particles (a) should be relatively large in terms of sensitivity and white spots. It is considered good. On the other hand, the thermal transfer image-receiving sheet of Comparative Example 1 in which the volume average particle diameter of the hollow particles (a) is 15 μm is inferior in appearance but having a good sensitivity and little white spots, and the thickness of the hollow particle (a) layer is 5 μm. The thermal transfer image-receiving sheet of Comparative Example 2 has low sensitivity and a lot of white spots are generated. The thermal transfer image-receiving sheet of Comparative Example 3 has inferior sensitivity. The intermediate layer does not contain hollow particles (b) instead of the hollow particle (b) layer. It was found that the thermal transfer image-receiving sheet of Comparative Example 4 provided with a low evaluation.

Since the thermal transfer image-receiving sheet of the present invention has the above-described configuration, it is possible to obtain an image that is excellent in sensitivity, glossiness, smoothness, has less blurring, and has reduced white spots and roughness in highlight portions.

Claims (5)

In the thermal transfer image receiving sheet formed by laminating a hollow particle (a) layer made of hollow particles (a), a hollow particle (b) layer made of hollow particles (b) and a receiving layer in this order on the base sheet,
The base sheet is formed by laminating resin layers on both sides of a base paper,
The hollow particle (a) layer has a thickness of 10 to 20 μm,
The hollow particles (a) have a volume average particle size of 3 to 10 μm,
The hollow particles (b) have a volume average particle size of 0.5 to 1 μm. The thermal transfer image receiving sheet according to claim 1, wherein the hollow particle (a) layer has a density of 0.1 to 0.3 g / cm ³ . The thermal transfer image-receiving sheet according to claim 1 or 2, wherein the hollow particles (a) are pre-foamed particles that are foamed before forming the hollow particle (a) layer. The thermal transfer image receiving sheet according to any one of claims 1 to 3, wherein the hollow particle (a) layer contains the hollow particles (a) in an amount of 60 to 80% by mass. The thermal transfer image receiving sheet according to any one of claims 1 to 4, wherein an image is formed on the image receiving surface of the thermal transfer image receiving sheet, and then a protective layer is transferred to the image forming surface.