JP2012218234A - Thermal transfer receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly qualified thermal transfer receiving sheet that has sufficient blocking prevention properties and curling prevention properties even when placed in a high temperature or high humidity environment and causes no image reduction, and further generates no offset even when print matters are kept overlapped.SOLUTION: The thermal transfer receiving sheet has a sheet-like support element, an image receiving layer for receiving dye on one surface of the support element, and a back coat layer which is formed on the other surface of the sheet-like support element. The back coat layer contains no pigments and contains at least one kind of adhesive resin which is selected from styrene acrylic acid copolymers and styrene-maleic acid copolymers and has a glass transition temperature of 20 to 80°C and styrene-butadiene copolymers having a glass transition temperature of 0 to 30°C.

Description

  The present invention relates to a thermal transfer receiving sheet (hereinafter also simply referred to as a receiving sheet). More specifically, the present invention relates to a back coating layer (hereinafter also simply referred to as a back layer) of a receiving sheet.

  A high-quality color hard copy printing system using a dye thermal transfer system includes a printer, a thermal transfer sheet (hereinafter also simply referred to as an ink ribbon), and a receiving sheet. As a general method for forming a color image on a receiving sheet, an ink ribbon in which a color material layer composed of three or four colors of yellow, magenta, cyan, and black as necessary is provided in a surface sequential manner, and an image A receiving sheet provided with a receiving layer (hereinafter simply referred to as a receiving layer) is brought into intimate contact and passed between a heating device pressed with a constant pressure and a platen roller. At that time, the heat generating portion of the heating device is selectively heated according to the image information, and the dye contained in the color material layer of the ink ribbon is transferred to the receiving layer of the receiving sheet to form an image. The ink ribbon is provided with three or four color material layers in a surface sequence, and different colors are sequentially transferred to the same position on the receiving sheet in three or four times, and each color is superimposed. As a result, a color image is formed.

  In general, the receiving sheet is formed on one side of the sheet-like support and the sheet-like support, and is formed on the other side of the sheet-like support, and a receiving layer excellent in the dyeing property of the dye transferred from the ink ribbon. It is formed from the back surface layer provided with the blocking prevention property with a receiving layer.

  In the manufacturing process, the receiving sheet is coated with the receiving layer paint and the back layer paint, dried, wound up in a roll, and stored. Is normal. The receiving layer is mainly composed of a thermoplastic resin to which the color material layer of the ink ribbon is easily transferred. For this reason, the back surface layer is required to have a function of preventing sticking to the receiving layer (so-called blocking). When blocking occurs, the glossiness of the surface of the receiving layer decreases, so that not only the appearance as a receiving sheet is impaired and the commercial value decreases, but also the smoothness of the surface of the receiving layer decreases, so that the image quality is improved when forming a color image. Remarkably worse.

  Furthermore, when the printed matter with the dye transferred to the image receiving layer is stored in an overlapping manner, depending on the material and shape of the back side of the receiving sheet, the dye in the image receiving layer may be transferred to the back side of the receiving sheet (back side). There was also a problem that the product value of the printed material was impaired.

  Some proposals have been made for the purpose of preventing blocking between the receiving layer surface and the back layer surface of the thermal transfer receiving sheet. A method of providing an acrylic resin layer as a “surface layer” on the surface of the receiving layer (for example, see Patent Document 1), a back layer containing microsilica and cellulose acetate (for example, see Patent Document 2), and an abrasive. A back layer (for example, refer to Patent Document 3) is disclosed.

  However, when a “surface layer” is provided on the surface of the receiving layer, there is a problem that the transfer of the dye from the colorant layer of the ink ribbon to the receiving sheet is hindered and the image quality and sensitivity are lowered. When microsilica or abrasive is contained in the back layer, a certain degree of blocking prevention effect can be expected due to the reduction of the contact area between the receiving layer and the back layer. However, microsilica and abrasive fall off from the back layer (so-called “powder” ”) And move to the surface of the receiving layer, preventing the migration of the dye and causing white spots in the image. Further, there is a problem in that the convex portion formed by the microsilica or the abrasive on the back layer transfers the shape to the surface of the receiving layer to form a concave portion on the surface of the receiving layer, thereby causing white spots in the image.

  Furthermore, a back layer (for example, see Patent Documents 4 to 7) having a nylon filler and a fixing agent has been proposed. The back layer has a high anti-blocking effect, and the nylon filler is relatively soft, so that it is difficult to cause a white spot phenomenon due to shape transfer to the receiving layer.

  However, in recent years, in the field of photographic printing, not only small-sized consumer printers that use single-sheet receiving sheets, but also commercial printers that incorporate roll-shaped receiving sheets in the apparatus are increasing. The roll-shaped receiving sheet set in the printer is often left for a long time in a state where the tension by the transport mechanism is applied, and the tension exerts a strong pressing force on the receiving layer and the back surface of the receiving sheet. Is generated.

  Commercial printers are used in various climatic areas, and when the roll-shaped receiving sheet loaded in the printer is placed in a high-temperature environment for a long time, the nylon filler protrudes from the back layer. There is a problem in that the receiving layer is thermoplastically deformed to generate a concave portion, and a white spot phenomenon is generated in a photographic image. Or, if it is a receiving sheet using paper whose main component is pulp, the base material absorbs moisture and softens when left in a high humidity environment for a long time, and the convex portion of the nylon filler is buried in the base material. Therefore, there is a problem that the spacer effect is lost and blocking occurs.

JP 2003-94843 A (2nd page) JP-A-8-230337 (2nd page) JP 5-116472 A (page 2) JP-A-7-101163 (2nd page) JP-A-8-118822 (second page) JP 2000-335120 A (2nd page) JP 2006-21431 A (page 2)

  The present invention has been made in view of the above circumstances, and the present invention provides a back coating layer for a receiving sheet even when the receiving sheet is placed in a high temperature or high humidity environment with the front and back contacting each other. However, it has sufficient anti-blocking properties and anti-curl properties with the image receiving layer, does not cause deterioration in image quality, and even when the printed matter is stored with the front and back contacting, the dye of the image is It is an object of the present invention to provide a high-quality thermal transfer receiving sheet that does not transfer from the image receiving layer to the back layer (setback).

(1) A dye thermal transfer receiving sheet having a sheet-like support, an image receiving layer for receiving a dye on one side of the support, and a back coating layer on the other side of the support. Styrene / acrylic acid copolymer and styrene / maleic acid copolymer, at least one adhesive resin having a glass transition temperature of 20 to 80 ° C., and styrene / butadiene having a glass transition temperature of 0 to 30 ° C. A thermal transfer receiving sheet containing a copolymer.
(2) At least one adhesive resin selected from the styrene / acrylic acid copolymer and styrene / maleic acid copolymer and having a glass transition temperature of 20 to 80 ° C. and the glass transition temperature of 0 to 30 ° C. The thermal transfer receiving sheet according to (1), wherein the solid content ratio of the styrene / butadiene copolymer is in the range of 9: 1 to 1: 1.
(3) The thermal transfer receiving sheet according to (1) to (2), wherein the back coating layer has a smoothness of 50 to 800 seconds.
(4) The thermal transfer receiving sheet according to (1) to (3), wherein the solid coating amount of the back coating layer is 1 to 10 g / m ² .

  According to the present invention, even when placed in a high temperature or high humidity environment, the back coating layer of the thermal transfer receiving sheet has sufficient anti-blocking and anti-curling properties in contact with the image receiving layer, and image quality is degraded. Furthermore, it is intended to provide a high-quality receiving sheet that does not cause image dye to transfer from the image receiving layer to the back layer even if the prints are stored in layers. It is.

Hereinafter, the present invention will be described in more detail.
(Configuration of thermal transfer receiving sheet)
The receiving sheet of the present invention has a sheet-like support, an image receiving layer for receiving a dye on one side of the support, and a back coating layer on the other side of the support.

(Sheet support)
Examples of the sheet-like support used in the receiving sheet of the present invention include a film substrate made of polyethylene terephthalate or polyolefin, a nonwoven fabric substrate made of synthetic fiber or natural fiber, paper equipment made from pulp as a main component, or the like. A laminated base material bonded with materials is used.

  For example, as a base material having pulp as a main component, high-quality paper (acid paper, neutral paper), medium-quality paper, coated paper, art paper, and glassine paper can be mentioned. Furthermore, a sheet-like support obtained by resin-laminating the image receiving layer surface side of a base paper mainly composed of pulp, or a sheet-like support obtained by laminating and laminating sheets mainly composed of synthetic resin may be used.

  Sheets mainly composed of synthetic resin include polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters such as polyethylene terephthalate (PET), polyamide (PA), polyvinyl chloride (PVC), and polystyrene (PS). And polycarbonate (PC). Examples of the porous stretched sheets include synthetic paper, porous polyester sheet, and the like mainly composed of a thermoplastic resin such as polyolefin and polyester.

  Further, on the image receiving layer surface side of the sheet-like support, a low-density film having voids in the interior and hollow particles for the purpose of imparting heat insulation and cushioning properties in order to improve image sharpness and image uniformity. The coating layer containing can also be laminated.

(Back coating layer)
The back coating layer of the present invention is selected from styrene / acrylic acid copolymers and styrene / maleic acid copolymers, and has at least one adhesive resin having a glass transition temperature of 20 to 80 ° C., and a glass transition temperature of 0. It is formed by applying a coating solution containing a styrene-butadiene copolymer at -30 ° C.

  The glass transition temperature here is a glass transition temperature based on JIS K7121. It is obtained by measuring the endothermic amount when the temperature of the test piece is raised at a constant speed with a differential scanning calorific value type (DSC), and is defined in JIS C 6481.

  The styrene / acrylic acid copolymer used in the present invention is obtained by copolymerizing at least one styrene-containing monomer as a polymerization monomer and at least one acrylic acid-based monomer copolymerizable with the styrene-containing monomer. It is a manufactured resin.

  Examples of the styrene-containing monomer include styrene and styrene derivatives such as α-methylstyrene, paramethylstyrene, t-butylstyrene, and chlorostyrene.

  Examples of the acrylic monomer include acrylic acid such as methyl acrylate, methyl methacrylate, ethyl methacrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, and esters of methacrylic acid.

  The styrene / maleic acid copolymer used in the present invention is a copolymer of at least one styrene-containing monomer as a polymerization monomer and maleic acid or a maleic acid-containing monomer, or maleic anhydride or a maleic anhydride-containing monomer. It is a resin manufactured by

  In addition, a styrene / acrylic acid copolymer or a styrene / maleic acid copolymer obtained by copolymerizing a monomer other than the above-mentioned monomers as a polymerization monomer may be used as long as the effects of the present invention are not impaired.

  The styrene / acrylic acid copolymer or styrene / maleic acid copolymer used in the present invention preferably has an acid value of 150 or more. By using a copolymer synthesized to have an acid value of 150 or more, it becomes water-soluble, and a stable back surface coating solution can be obtained using a solvent containing water as a main component. As a result, a uniform back coating layer can be formed and a good anti-curl effect can be obtained.

  The styrene / acrylic acid copolymer or styrene / maleic acid copolymer used in the present invention is an adhesive resin having a glass transition temperature (hereinafter also referred to as Tg) of 20 to 80 ° C., more preferably, Tg is 30 to 70 ° C. If it is less than 20 ° C, blocking with the surface of the receiving layer and set-off are likely to occur. , Printer trouble is likely to occur.

  The styrene / acrylic acid copolymer or styrene / maleic acid copolymer used in the present invention can be used as commercial products such as Polymeron 326 and Polymeron 1318 (Arakawa Chemical Co., Ltd.).

  The styrene-butadiene copolymer used in the present invention has a glass transition temperature in the range of 0 to 30 ° C. If the glass transition temperature is less than 0 ° C., blocking with the receiving layer surface is likely to occur, and if the glass transition temperature exceeds 30 ° C., the film-forming property of the back surface coating layer is deteriorated, resulting in poor image quality due to powder falling. .

  The solid content ratio of the adhesive resin and the styrene / butadiene copolymer is preferably in the range of 9: 1 to 1: 1.

  By setting the maximum ratio of the adhesive resin to the styrene / butadiene copolymer to be 9, the adhesiveness of the back surface coating layer to the sheet-like support is increased, and a part of the back surface coating layer is transferred to form white It is possible to prevent image defects such as omission.

By setting the minimum ratio of the adhesive resin to the styrene / butadiene copolymer to 1, the effect of preventing curling of the receiving sheet due to environmental changes can be enhanced.

The smoothness of the back coating layer is preferably in the range of 50 to 800 seconds, and more preferably in the range of 120 to 80 seconds. By making it 50 seconds or more, the effect of preventing image defects can be further enhanced. By setting it to 800 seconds or less, the effect of preventing blocking with the receiving layer can be further enhanced.
If the smoothness of the back surface coating layer after coating and drying does not fall within the desired range, smoothing can be achieved by various known smoothing processes such as calendering or roughening process by contact with a rough surface roll. It is also possible to adjust the degree.

  In addition, the smoothness said here is the smoothness measured based on JISP8119.

  In the back coating layer of the present invention, a pigment can be added within a range not to impair the effects of the present invention, but the back coating layer contains a pigment that forms protrusions on the back coating layer. Preferably not. Specifically, it is preferable that the back coating layer contains a pigment in such a range that the smoothness of the back coating layer is adjusted to the preferred smoothness range.

  The back surface coating layer of the present invention prevents blocking and setback by setting the composition, blending ratio, and combination of the adhesive resin to a specific range. For this reason, there is no need for roughening with a pigment, and when rolled up, there is no dent or roughening of the receiving layer surface due to unevenness on the back surface, and image quality does not deteriorate.

The coating amount of the back coating layer is preferably in the range of 1 to 10 g / m ^2, by a 1 g / m ² or more, it is possible to enhance the anti-blocking effect. Moreover, the curl prevention and blocking prevention effects reach substantially saturation at 10 g / m ² .

(Image receiving layer)
The receiving layer contains a resin having a high affinity for the dye transferred from the ink ribbon and having a good dye dyeing property as a main component. As dye-dyeing resins, polyester resins, polycarbonate resins, polyvinyl chloride resins, polyvinyl chloride / vinyl acetate copolymer resins, polyvinyl acetal resins, polyvinyl butyral resins, polyurethane resins, polystyrene resins, polyacrylate resins, Examples thereof include cellulose derivative resins such as cellulose acetate butyrate, thermoplastic resins such as polyamide resin, and active energy ray curable resins.

  In addition, in order to prevent the receiving layer and the ink ribbon from being fused by heating with a thermal head during printing, at least one kind of a crosslinking agent, a release agent, a lubricant, etc. is added to the receiving layer as an additive. It is preferable to be blended as Furthermore, if necessary, one or more kinds of fluorescent dyes, plasticizers, antioxidants, pigments, fillers, ultraviolet absorbers, light stabilizers, antistatic agents and the like may be added to the above-mentioned receiving layer. These additives may be mixed with the component for forming the receiving layer before coating, or may be coated on and / or below the receiving layer as a coating layer different from the receiving layer. .

  The receiving layer is formed by appropriately adjusting the coating solution for the receiving layer by dissolving or dispersing necessary additives such as a dye-dyeing resin and a crosslinking agent and a release agent in an organic solvent or water as appropriate. The coater can be applied and dried on a sheet-like support and further heated and cured as necessary. It is also possible to prepare the dye-dyeable resin and the necessary additives such as a crosslinking agent and a release agent as a solvent-free coating material for the receiving layer and apply it by coating or heat melting. is there.

Solid coating amount of the receiving layer is preferably ^{0.1~12g / m 2, 1~10g / m} 2 is more preferable. When the solid content coating amount of the receiving layer is less than 0.1 g / m ² , the receiving layer may not be able to completely cover the surface of the undercoat layer. There may be a fusing problem that the ink ribbon and the ink ribbon are bonded. On the other hand, when the solid content coating amount exceeds 12 g / m ² , not only is the coating effect saturated, which is uneconomical, but also the coating layer strength of the receiving layer is lowered and dot missing of the image may occur. is there. Alternatively, when the coating film thickness is excessive, the heat insulating effect of the undercoat layer is not sufficiently exhibited, and the image density may be lowered.

(Undercoat layer)
In the present invention, an undercoat layer containing hollow particles is provided on the image receiving layer surface side of the sheet-like support for the purpose of imparting heat insulating properties and cushioning properties in order to improve image clarity and image uniformity. Can do.
Examples of the material for forming the walls of the hollow particles used in the undercoat layer include polymers of acrylonitrile, vinylidene chloride, styrene, and acrylate esters. Examples of a method for producing these hollow particles include a method in which microcapsules in which butane gas is sealed in resin particles are heated and foamed, an emulsion polymerization method, and the like.
The particle size of the hollow particles is preferably 0.1 to 10 μm. When the particle size of the hollow particles is less than 0.1 μm, the walls of the hollow particles become thin and the heat resistance is insufficient, and is easily broken in the coating and drying process. On the other hand, when the thickness exceeds 10 μm, the surface roughness of the obtained receiving sheet may increase, resulting in poor image uniformity.

The volume hollow ratio of the hollow particles is preferably 50 to 90%. When the volumetric hollow ratio of the hollow particles is less than 50%, the effect of imparting heat insulating properties and cushioning properties may be insufficient. If it exceeds 90%, the walls of the hollow particles become thin and the durability may be lowered.
The coating amount of the undercoat layer is preferably 1 to 30 g / m ² . If the coating amount of the undercoat layer is less than 1 g / m ² , sufficient heat insulating properties and cushioning properties cannot be expected, and if it exceeds 30 g / m ² , the effect obtained is small for an increase in cost.

(Barrier layer)
In the present invention, a barrier layer (intermediate layer) can be provided between the undercoat layer and the receiving layer.
The purpose of the barrier layer is effective as a barrier for forming the receiving layer with a predetermined thickness and as a barrier for preventing image blurring. The barrier layer contains a resin, a pigment or the like depending on the purpose.

  Each of the layers can be obtained by coating and drying a coating solution using an organic solvent and / or water as a dispersion medium using various known coating facilities. Various additives such as wetting agents, dispersants, thickeners, antifoaming agents, colorants, antistatic agents, preservatives and the like used in the production of general coated paper are appropriately added to the coating layer. Can do.

(Calendar processing)
The receiving sheet may be calendered. By the calendar process, the unevenness of the surface of the obtained receiving sheet can be reduced, and a uniform image can be obtained. The calendar process may be performed at any stage. As the calendar device used for the calendar process, a calendar device generally used in the paper industry such as a super calendar, a soft calendar, a gloss calendar, a clearance calendar, or the like can be appropriately used.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Further, “parts” and “%” in the examples represent “parts by mass” and “mass%”, respectively, and are solid contents unless otherwise specified.

Example 1
(Creation of thermal transfer receiving sheet)
As the sheet-like support, high-quality paper having a thickness of 150 μm was used. An undercoat layer coating solution having the following composition is coated on one side of the sheet-like support so that the solid content coating amount is 12 g / m ² and dried to form an undercoat layer. An image receiving layer was formed by coating and drying an image receiving layer coating solution having the following composition so that the solid coating amount was 2 g / m ² . Further, on the opposite surface of the sheet-like support provided with the image receiving layer, a back surface layer coating liquid having the following composition was applied and dried so that the solid content coating amount was 2 g / m ^2. To obtain a thermal transfer receiving sheet.

(Adjustment of undercoat layer coating solution)
A material having the following composition was stirred to prepare a coating solution for an undercoat layer.
Pre-foamed hollow particles (average particle diameter 3.2 μm, volume hollowness 85%) made of a copolymer mainly composed of acrylonitrile and methacrylonitrile 35 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 10 parts acrylic Resin (trade name: FK-Y0692, manufactured by Chuo Rika Kogyo Co., Ltd.) 30 parts water 200 parts (preparation of image-receiving layer coating solution)
90 parts of vinyl chloride vinyl acetate copolymer emulsion (trade name: Viniblanc 603, manufactured by Nissin Chemical, Tg: 60 ° C)
8 parts of carbodiimide-based crosslinking agent (trade name: Carbodilite E-02, manufactured by Nisshinbo Co., Ltd.)
2 parts polysiloxane graft acrylic resin (trade name: US450, manufactured by Toagosei)
300 parts of water (coating liquid for back layer-1)
60 parts by mass of a styrene / maleic acid copolymer (manufactured by Arakawa Chemical Industries, trade name: Polymeron 1318, Tg = 68 ° C.)
40 parts by mass of styrene / butadiene copolymer (manufactured by JSR, trade name: JSR0850Z, Tg = 8 ° C.)
500 parts by weight of water

(Example 2)
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the backside layer coating liquid-2 having the following composition was used instead of the backside layer coating liquid-1 in Example 1.
(Back surface layer coating liquid-2)
85 parts by mass of a styrene / acrylic acid copolymer (manufactured by Arakawa Chemical Industries, trade name: Polymeron 326, Tg = 59 ° C.)
15 parts by mass of styrene / butadiene copolymer (manufactured by JSR, trade name: JSR0850Z, Tg = 8 ° C.)
500 parts by weight of water

(Example 3)
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the backside layer coating solution-3 having the following composition was used instead of the backside layer coating solution-1 of Example 1.
(Back surface layer coating solution-3)
85 parts by mass of a styrene / acrylic acid copolymer (manufactured by Arakawa Chemical Industries, trade name: Polymeron 326, Tg = 59 ° C.)
15 parts by mass of styrene / butadiene copolymer (manufactured by JSR, trade name: JSR0850Z, Tg = 8 ° C.)
Aluminum hydroxide pigment (manufactured by Nippon Light Metal Co., Ltd., B703) 10 parts by weight Water 500 parts by weight

Example 4
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the backside layer coating liquid-4 having the following composition was used instead of the backside layer coating liquid-1 in Example 1.
(Back surface layer coating solution-4)
55 parts by mass of styrene / acrylic acid copolymer (manufactured by Johnson Polymer Co., Ltd., trade name: 537, Tg = 49 ° C.)
45 parts by mass of styrene / butadiene copolymer (manufactured by JSR Nippon Zeon Co., Ltd., trade name: LX415M, Tg = 27 ° C.)
500 parts by weight of water

(Example 5)
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the back layer coating solution-5 having the following composition was used instead of the back layer coating solution-1 of Example 1.
(Back surface layer coating solution-5)
55 parts by mass of styrene / acrylic acid copolymer (manufactured by DIC, trade name: CG-8400, Tg = 25 ° C.)
45 parts by mass of styrene / butadiene copolymer (manufactured by JSR Nippon Zeon Co., Ltd., trade name: LX415M, Tg = 27 ° C.)
500 parts by weight of water

(Example 6)
Thermal transfer acceptance in the same manner as in Example 1 except that the back layer was coated and dried so that the solid coating amount was 0.5 g / m ² and the back layer was formed. A sheet was obtained.

(Example 7)
In Example 1, the thermal transfer receiving sheet was prepared in the same manner as in Example 1 except that the back layer was coated and dried so that the solid coating amount was 11 g / m ² and dried to form the back layer. Obtained.

(Comparative Example 1)
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the back layer coating solution-6 having the following composition was used instead of the back layer coating solution-1 of Example 1.
(Back surface layer coating liquid -6)
85 parts by mass of styrene / acrylic acid copolymer (manufactured by Johnson Polymer Co., Ltd., trade name: 631, Tg = 87 ° C.)
15 parts by mass of styrene / butadiene copolymer (manufactured by JSR, trade name: JSR0850Z, Tg = 8 ° C.)
500 parts by weight of water

(Comparative Example 2)
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the back layer coating solution -7 having the following composition was used instead of the back layer coating solution -1 in Example 1.
(Back surface layer coating solution -7)
85 parts by mass of styrene / maleic acid copolymer (manufactured by Arakawa Chemical Co., Ltd., trade name: KS1570S, Tg = 114 ° C.)
15 parts by mass of styrene / butadiene copolymer (manufactured by JSR, trade name: JSR0850Z, Tg = 8 ° C.)
500 parts by weight of water

(Comparative Example 3)
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the back layer coating solution-8 having the following composition was used instead of the back layer coating solution-1 of Example 1.
(Back surface layer coating solution -8)
85 parts by mass of styrene / acrylic acid copolymer (manufactured by DIC, trade name: EC-740EF, Tg = 18 ° C.)
15 parts by mass of styrene / butadiene copolymer (manufactured by JSR, trade name: JSR0850Z, Tg = 8 ° C.)
500 parts by weight of water

(Comparative Example 4)
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the backside layer coating solution-9 having the following composition was used instead of the backside layer coating solution-1 in Example 1.
(Back surface layer coating solution-9)
85 parts by mass of acrylic resin (manufactured by DIC, trade name: CP-6190, Tg = 43 ° C.)
15 parts by mass of styrene / butadiene copolymer (manufactured by JSR, trade name: JSR0850Z, Tg = 8 ° C.)
500 parts by weight of water

(Comparative Example 5)
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the back layer coating solution-10 having the following composition was used instead of the back layer coating solution-1 of Example 1.
(Back surface layer coating solution-10)
60 parts by mass of a styrene / acrylic acid copolymer (manufactured by Arakawa Chemical Industries, trade name: Polymeron 1318, Tg = 68 ° C.)
40 parts by mass of a styrene / butadiene copolymer (manufactured by Nippon Zeon Co., Ltd., trade name: LX433C, Tg = 50 ° C.)

(Comparative Example 6)
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the back layer coating solution-11 having the following composition was used instead of the back layer coating solution-1 of Example 1.
(Coating liquid for back layer-11)
55 parts by mass of a styrene / acrylic acid copolymer (manufactured by Arakawa Chemical Industries, trade name: Polymeron 326, Tg = 59 ° C.)
45 parts by mass of styrene / butadiene copolymer (manufactured by Nippon Zeon Co., Ltd., trade name: LX435, Tg = -14 ° C.)
500 parts by weight of water

(Comparative Example 7)
A thermal transfer receiving sheet was obtained in the same manner as in Example 1 except that the back layer coating solution-12 having the following composition was used instead of the back layer coating solution-1 of Example 1.
(Coating liquid for back layer-12)
60 parts by mass of styrene / maleic acid copolymer (manufactured by Arakawa Chemical Co., Ltd., trade name: KS1570S, Tg = 114 ° C.)
40 parts by mass of styrene / butadiene copolymer (manufactured by Nippon Zeon Co., Ltd., trade name: LX435, Tg = -14 ° C.)
3 parts by mass of nylon filler (trade name: 2001EXDNAT1, manufactured by Elfalt Chem, average particle size 10 μm)
500 parts by weight of water

(quality evaluation)
About the coating liquid for back surface coating layers and a receiving sheet obtained in said Examples 1-7 and Comparative Examples 1-7, quality evaluation of the following item was performed and the evaluation result was shown in Table 1 and Table 2.

[Back surface smoothness]
The smoothness of the surface provided with the back surface layer of the receiving sheet was measured based on JIS P 8119.

[Set-off test]
The receiving sheet was set in a sublimation thermal transfer printer (trademark: DR-100, manufactured by Sony Corporation), and a black solid image was printed. The printed image receiving layer surface and the back coating layer surface of the receiving sheet were brought into contact with each other and superposed, and stored in a 60 ° C. environment for 48 hours under a pressure of 200 g / cm ² . After storage, the optical density of the back coating layer surface that was in contact with the printed image receiving layer surface was measured with a Macbeth densitometer (trademark: RD-914), and the set-off property was evaluated according to the following criteria. The optical density of (black) on the back coating layer surface before the set-off test was 0.05.
◯: The optical density of the back coating layer surface is less than 0.10, which is excellent.
X: The optical density of the back surface coating layer surface is 0.10 or more, which is not practical.

[Blocking test]
The receiving sheet was put in contact with the back surface and the unprinted receiving layer surface, and stored in an environment of 40 ° C. and 75% RH for 24 hours under a pressure of 200 g / cm ² . After storage, blocking properties were evaluated according to the following criteria.
○: There is no adhesion between the back surface coating layer and the receiving layer surface, and it can be removed without any problem.
Δ: Slight peeling noise is generated when the back surface coating layer and the receiving layer surface are peeled off, but there is no tearing or gloss reduction, and there is no problem in practical use.
X: When the back surface coating layer and the receiving layer surface are adhered and peeled off, tearing occurs, and this is not practical.

[Image quality (outline)]
After the evaluation of the blocking test is completed, the receiving sheet is set in a sublimation thermal transfer printer (trademark: DR-100, manufactured by Sony Corporation), and after printing a halftone pattern in an environment of 20 ° C. and 65% RH, printing The image quality of the objects was evaluated according to the following criteria.
◯: No white spots are seen and excellent.
Δ: Slight white spots are observed, but there is no practical problem.
X: White spots are conspicuous and not practical.

[Wrapping of receiving sheet after printing (print curl)]
The receiving sheet is set on a sublimation thermal transfer printer (trademark: DR-100, manufactured by Sony Corporation), and the size is 2L (printing direction length 180 mm × width direction length 127 mm) in an environment of 20 ° C. and 45% RH. Then, immediately after the three-color overlay image of solid black and overlaminate printing, the height of the warp of the four corners of the receiving sheet was measured and evaluated according to the following criteria.
○: The height of warping at the four corners is less than 20 mm and excellent.
(Triangle | delta): Although the height of the curvature of one or more places in four corners is 20 mm or more, all the heights of the curvature of four corners are less than 25 mm, and there is no problem practically.
X: The height of one or more warps in the four corners is 25 mm or more, which is not practical.

[Coating strength of back coating layer]
An adhesive tape was applied to the surface of the back surface coating layer of the receiving sheet, and the back surface coating layer was peeled off when peeled at a constant speed.
○: There is no problem in the coating film strength because the back coating layer is not taken on the adhesive tape.
(Triangle | delta): Although the slight resin part of a back surface coating layer adheres to an adhesive tape, it is the coating-film intensity | strength which is satisfactory practically.
X: The back surface coating layer peeled off from the paper layer adheres to the adhesive tape. There is a very high possibility that powder will fall off, and it is a level that is not practical.

  As is apparent from Tables 1 and 2, in the thermal transfer receiving sheets of Examples 1 to 7, the back coating layer has sufficient anti-blocking and anti-curling properties in contact with the image receiving layer, and the image quality It is an excellent thermal transfer receiving sheet that does not cause deterioration, and does not cause image dye transfer from the image receiving layer to the back layer (setback) even when the printed matter is stored in layers.

  According to the present invention, even when the receiving sheet is placed in a high-temperature or high-humidity environment with the front and back in contact with each other, the back coating layer of the receiving sheet has sufficient anti-blocking properties and anti-curling properties with the image receiving layer. In addition, there is no deterioration in image quality, and there is no transfer of the dye of the image from the image receiving layer to the back layer even when the print is stored in a state where the front and back are in contact with each other. A thermal transfer receiving sheet with high image quality can be provided.

Claims (4)

In a dye thermal transfer receiving sheet having a sheet-like support, an image receiving layer for receiving a dye on one side of the support, and a back coating layer on the other side of the support, the back coating layer is made of styrene At least one adhesive resin selected from an acrylic acid copolymer and a styrene / maleic acid copolymer and having a glass transition temperature of 20 to 80 ° C., and a styrene / butadiene copolymer having a glass transition temperature of 0 to 30 ° C. Containing a thermal transfer receiving sheet. At least one adhesive resin selected from the styrene / acrylic acid copolymer and styrene / maleic acid copolymer and having a glass transition temperature of 20 to 80 ° C., and styrene / copolymer having a glass transition temperature of 0 to 30 ° C. The thermal transfer receiving sheet according to claim 1, wherein the solid content ratio with the butadiene copolymer is in the range of 9: 1 to 1: 1. The thermal transfer receiving sheet according to claim 1 or 2, wherein the back coating layer has a smoothness of 50 to 800 seconds. The thermal transfer receiving sheet according to claim 1, wherein the solid coating amount of the back surface coating layer is 1 to 10 g / m ² .