GB2353101A - Thermal transfer image receiving material - Google Patents

Abstract

A thermal transfer image receiving material has an image receiving layer which comprises at least a metal ion containing compound and an acrylic resin which includes an acyl based copolymer having at least one styrene (or derivative) monomer unit, with the acrylic resin having a melt flow rate of at least 20g/10 ml specified in JIS K 7210. Also disclosed is a thermal transfer recording material comprising (1) an ink sheet, (2) an image receiving material comprising an image receiving layer on a support, with the layer containing a resin having a melt flow rate of at least 20g/10 minutes and (3) a protective sheet.

Description

2353101 1 THERMAL TRANSFER IMAGE RECEIVING MATERIAL AND THERMAL TRANSFER

RECORDING METHOD

THCHNICAL FIELD OF THE INVENTION

The present invention relates to an image receiving material which carries out thermal transfer recording employing a post-chelate type sublimable dye, and a thermal transfer recording material protecting a thermal transfer image and a method which carries out thermal transfer recording.

BACKGROUND OF THE INVENTION

As color or black-and-white image forming techniques, a technique is known in which an ink sheet comprising sublimable dyes is arranged so as to face the image receiving layer of an image receiving element, and is heated employing a thermal head and the like so that an image is f ormed by I I 2 4334 transferring imagewise said sublimable dyes to said image receiving layer. Such an image forming method is a digital image recording method which is capable of reproducing image quality equal to that of conventional silver salt photography. Accordingly, in recent years, the development of printers and ink sheets, and image receiving sheets has progressed. Image prints produced employing sublimable dyes exhibit good image quality. However, problems have occurred in which the image retention quality is inferior, and particularly, those prints tend to suffer from discoloration due to light or color bleeding.

Conventionally, in order to improve the image retention quality of image samples produced by employing the sublimation thermal transfer method, binders constituting the image receiving layer have been investigated covering various aspects. Japanese Patent Publication open to Public Inspection No. 63-319188 discloses a technique in which an image receiving body, which exhibits excellent image retention quality, is obtained by employing a copolymer resin comprised of acrylonitrile and styrene as indispensable components. However, sufficient effects are not obtained. Further, problems occur in which the image density decreases. Japanese Patent Publication open to Public Inspection No. 62189195 discloses that light fastness is improved by 3 4334 incorporating styrene based resins into an image receiving layer. The durability of acrylic copolymer resins themselves is excellent. Commonly, however, many of those exhibit the low thermal diffusion rate of dyes. When no modification is carried out, the dyes are exposed on the surface of the image receiving layer, which tend to be decomposed due to light as well as heat and moisture.

On the other hand, in such transfer image forming techniques, the image retention quality of the sublimable dye images in which metal chelates are formed by allowing a metal ion containing compound to react with a post-chelate type dye (post-chelate dye) as the sublimable dye was markedly improved compared to conventional sublimable dye images. it is known in the art that the image retention quality of the post-chelate sublimable dye image is improved as the chelation ratio increases in which a post-chelate dye supplied from an ink sheet bonds to a metal source in the image receiving layer. Specifically, when an image-formed image receiving material is stored at high temperature and high humidity for an extended time of period, neither the discoloration of the dye nor bleeding results, and the light fastness is superior to images only comprised of conventional sublimable dyes.

4 4334 When image recording is carried out employing such post-chelate dyes, the resulting image retention quality is superior to that of conventional sublimation thermal transfer materials. However there have been problems in which when the resulting image is stored under severe conditions for a relatively long period of time, the image retention quality is degraded due to the decomposition caused by oxygen and moisture, which have been included into the image receiving layer. The present inventors have succeeded that the light fastness as well as image retention quality, at high temperature and high humidity, is markedly improved by employing as the binder of the image receiving layer copolymer resins (SAN copolymer resins), which are comprised of acrylonitrile and styrene as the indispensable components.

However, common SAN copolymer resins do not result in high image density due to the low dye transferabilitydiffusibility. Alternatively, when the post-chelate technique is used, there have been problems in which chelate reactivity is lowered to specifically degrade the image retention quality. For example, Japanese Patent Publication Open to Public Inspection No. 4308794 describes that styrene-acrylic copolymer resins are incorporated into a post-chelate type thermal transfer image receiving layer. However, in this case, chelation tends not to proceed due to 4334 the low thermal diffusibility of dyes, and as a result, light fastness is degraded. Further, in either thermal transfer systems, when dyes are in the exposed state, during physical contact with anything (for example, a transparent sheet employed for an album, a vinyl sheet employed for a commutationticket holder, a mutual contact between printed surfaces, and the like) the dyes are transferred to the material in contact. As a result, the dyes may fade or particularly when print surfaces are faced with each other, an area which is not printed may suffer from background staining. In order to minimize the exposure of dyes on the surface, techniques are known in which acrylic copolymers having a low Tg are employed, and the thermal diffusion of dyes is enhanced by incorporating plasticizers into the image receiving layer as described in Japanese Patent Publication Open to Public Inspection No. 11-221969. However, when the thermal diffusibility of dyes in the image receiving layer is enhanced, the bleeding as well as discoloration of the image occurs and in addition, the re-transfer of dyes due to the aforementioned physical contact is adversely enhanced. incidentally, employed as techniques to improve image durability (mainly abrasion resistance of a surface) is one in which a protective layer as well as a laminating material is provided on the image surface after printing. However,

6 4334 when such a protective layer as well as the laminating material is provided, problems occur in which images suffer from bleeding. Further, when the releasing properties of the image receiving layer are improved in order to minimize the thermal fusion with an ink sheet during printing, problems occur in which said surface layer as well as said laminate material is subjected to insufficient transfer adhesion with the image surface due to the excessively low surface activity of said image surface. During providing a protective layer comprised of acrylic resins and the like on an image surface employing thermal transfer, in order to improve adhesion with said protective layer, a heat-fusible adhesive layer is occasionally provided. However, the use of resins having a low Tg as well as a low softening point, to provide said adhesive layer with adhesive properties, results in bleeding due to heat and the like.

Further, regarding a technique to improve adhesion between a protective layer and an image receiving layer, the aforementioned Japanese Patent Publication Open to Public Inspection No. 11-221969 describes that in order to increase compatibility with the protective layer, an image receiving layer comprised of resins having a styrene skeleton or an acrylic skeleton is employed.

7 4334 SUMMY OF THE INVENTION In view of the foregoing, the present invention was accomplished. The first object of the present invention is to provide, upon forming images employing post-chelate technique a thermal transfer image receiving material which exhibits minimum image discoloration as well as image bleeding during the storage of an extended period of time under severe conditions, and is capable of obtaining sufficient image density as well as light fastness. The second object of the present invention is to provide a thermal transfer image receiving material which exhibits releasability; is capable of minimizing thermal fusion with an ink sheet; and further exhibits minimum image discoloration as well as image bleeding during the storage of an extended period of time under severe conditions. The third object of the present invention is to provide a thermal transfer image receiving material which does not degrade image retention quality when a protective layer is provided, and further in which a protective layer is correctly transferred and adhered onto said image receiving material. The fourth object of the present invention is to provide a thermal transfer recording material in which even when acrylic resins, which exhibit excellent durability but low dye transferability, are employed, dyes are not decomposed 8 4334 due to light, heat, and moisture and the re-transfer of dyes does not occur. The fifth object of the present invention is to provide a thermal transfer recording material in which when a protective layer is transferred onto an image-formed image receiving layer, compatibility between said protective layer and said image receiving layer is enhanced even in the absence of an adhesive layer and adhesion between said protective layer and said image receiving layer is improved. The sixth object of the present invention is to provide a thermal transfer recording material in which without adding an excessive amount of plasticizers and the like to an image receiving layer for the purpose of dye diffusion, dye diffusibility is improved and adhesion properties with said protective layer are enhanced.

The aforementioned objects are achieved employing the embodiments described below.

Item 1. In a thermal transfer image receiving material in which an image receiving layer is provided which is faced with an ink sheet comprising thermally diffusible dyes, and is heated imagewise with response to record signals so as to be capable of receiving the dyes of said ink sheet, a thermal transfer image receiving material characterized in that said image receiving layer comprises at least a metal ion containing compound, styrene, and an acrylonitrile resin 9 4334 together with an acrylic resin having a melt f low rate of at least 10g/10 ml specified in JIS K 7210.

Item 2. The thermal transfer image receiving material described in Item 1., characterized in comprising said image receiving layer having thereon a releasing layer containing a silicon compound.

Item 3. The thermal transfer image receiving material described in Item 2., characterized in that said silicon compound has at least one of an alkyl group, an alkylene group and a styryl group in its structure.

Item 4. A thermal transfer image receiving material characterized in comprising a support having thereon an image receiving layer comprising a metal ion containing compound and a releasing layer comprising a silicon compound having at least one of an alkyl group, an alkylene group and a styryl group, in said order.

Item 5. A thermal transfer recording material characterized in being comprised of three elements of 1) an ink sheet comprising a support having thereon an ink layer containing a thermally diffusible dye or a thermally diffusible dye precursor, 2) an image receiving material comprising a support having thereon an image receiving layer containing a resin having a melt flow rate of at least 10 g/10 minutes, and 3) a protective sheet having an image 4334 protective layer region prepared by applying onto a support a resin which can be thermally transferred onto the image surface of an thermal transfer image formed by transferring the dye described in 1) onto the image receiving material described in 2).

Item 6. The thermal transfer recording material described.

in Item 5., characterized in that the resin contained in said image receiving layer is an acryl based copolymer containing at least one type of acrylic monomers having an unsaturated double bond with at least a styrene monomer or derivatives thereof.

Item 7. The thermal transfer recording material described in Item 5. or 6., characterized in that said protective layer comprises at least one type selected from UV absorbers, antioxidants, and light stabilizers.

Item 8. The thermal transfer recording material described in Item 5., 6., or 7., characterized in that said ink layer comprises a chelatable dye as a thermal transfer dye precursor and said image receiving layer comprises a dye fixing material which is capable of reacting with said dye precursor.

Item 9. The thermal transfer recording material described in Item 5., 6., 7., or 8., characterized in that said protective sheet comprises a dye fixing material which is 11 4334 capable of forming a dye upon reacting with a thermally diffusible dye precursor.

Item 10. In a thermal transfer recording method in which an ink sheet comprising a thermally diffusible dye capable of forming a chelate compound with a metal ion containing compound is faced with a thermal transfer image receiving material provided with an image receiving layer capable of receiving said dye, and is heated imagewise in response to recording signals so that said dye of the ink sheet is transferred to the image receiving layer to form an image, and thereafter a transparent protective layer is provided onto the image surface, a thermal transfer recording method characterized in that said thermal transfer image receiving material comprises a support having thereon an image receiving layer comprising a metal ion containing compound, as well as a releasing layer comprising a silicon compound having at least one of an alkyl group, an alkylene group, and a styryl group in its structure, in said order.

Item 11. The thermal transfer recording method described in Item 10., characterized in that said transparent protective layer comprises an acrylic resin.

Item 12. A thermal transfer recording method characterized in that by employing the thermal transfer recording material described in Item S. through 9., an ink layer and an image 12 4334 receiving layer is faced with each other; an image is formed by heating imagewise, employing a thermal means; and a protective layer is thermally transferred employing a thermal means onto the surface of said image receiving layer on which an image is formed.

Based on finding that image density as well as light fastness is improved when the sensitivity of the post-chelate type sublimable dye is increased by enhancing the fluidity of a resin employed in an image receiving layer, the invention described in Item 1. above has been accomplished by discovering the use of a styrene -acryl oni tri le resin comprising "an acrylic resin having a melt flow value of 10 g/10 minutes specified in JIS K 7210, while comprising a styrene and acrylonitrile resins" which was used as the guide.

The invention according to Items 2. through 4, 10, and 11., has been accomplished by discovering that in order to improve releasability from an ink sheet, a releasable layer comprising a silicone compound having a specified group is provided onto the surface of an image receiving layer; as a result, adhesion between a surface protective layer and a thermal transfer image receiving material is improved and further, image heat resistance and moisture resistance, and image surface durability may coexist.

13 4334 Further, invention according to Items 5. through 9 has been accomplished by discovering that from the viewpoint of the migration properties of a dye during heating, when an image receiving layer comprising a resin having a melt flow value of at least 10 g/10 minutes is prepared, transferability is improved and further, excellent adhesion with a protective layer formed by thermal transfer after image formation is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a plan view showing one example of the embodiment of the arrangement of dye containing regions and a non-dye containing region in an ink sheet.

Fig. 2 is a schematic view of one example of a thermal transfer recording apparatus employed in the method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be detailed below. (1) The thermal transfer image receiving material (1) described in item 1 of the present invention is characterized in that the image receiving layer comprises at least a metal ion containing compound and an acrylic resin which includes an acryl based copolymer comprising at least one type of a 14 4334 styrene or derivative thereof as a monomer unit, wherein the acrylic resin has a melt flow rate of at least 20g/10 ml specified in JIS K 7210. The image receiving material 2) of item 5 comprises having a melt flow rate of at least 20 g/10 minutes specified in JIS K 7210.

The melt flow rate is determined by test method in accordance with JIS K 7210. The melt flow rate (MFR) is defined by a formula, with test temperature at 220 OC, test weight of 10.0 kgf by manual cutting method, MFR (220 OC, 10 kgf) = (600 x m) /t wherein, m is average mass of samples in g, t is sampling time of mass measurement in seconds. The unit of MFR is g /10 minutes.

In the thermal transfer image receiving material (1), the binder of the image receiving layer is comprised of styrene and acrylonitrile as the indispensable components together with an acrylic resin having a melt flow value of at least 20 g/10 minutes, specified in JIS K 7210. In order to obtain higher density images, an acrylic resin having a melt flow rate of at least 25 g/10 minutes is most preferably employed.

Copolymers of acrylic monomers may be any of those in which each monomers may be alternatively polymerized in regular order, and block copolymers of homopolymers of each is 4334 monomer, alternative copolymers, graft copolymers, and random copolymers.

Listed as the aforementioned acrylic monomers are acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, glycidyl methacrylate, maleic acid ester, maleic anhydride, maleic imide, acrylic amide, methacrylic amide, acrylonitrile, and the like.

Further, other than the aforementioned acrylic monomers, copolymers may be employed which are prepared together with other monomers having an unsaturated double bond, such as ethylene, ethylene chloride, propylene, isoprene, chloroprene, butadiene, pentadiene, cyclopnetadiene, intene, divinylbenzene, vinylidene chloride, allyl alcohol, vinyl acetate, vinyl propionate, itaconic acid, vinyl pyridine, vinyl pyrrolidone.

Listed as acrylic resins satisfying the aforementioned conditions are acrylic acid styrene (AS resin), styreneacrylonitrile copolymers (SAN resins), acrylonitrilespecialized acrylic rubber -acryloni tri le copolymers (AAS resins), acrylonitrile-ethylene propylene rubber-styrene copolymers (AES resins), acrylonitrile-butadiene rubberstyrene copolymers (ABS resins), and acrylonitrilechlorinated polyethylene-styrene copolymers (ACS resins) Those having a thermal deformation temperature of 60 to 120 16 4334 C result in improved image retention quality. In the present invention, of the aforementioned resins, the SAN resins are most preferably employed. In the acrylic resins comprised of styrene and acrylonitrile as indispensable components, the content ratio of acrylonitrile is preferably between 10 and 50 mole percent, and is more preferably between 15 and 30 mole percent.

These resins exhibit good compatibility with dyes, especially sublimable dyes capable of forming a chelate with a metal ion compound as well as dyes which have been subjected to chelate reaction so that dyes neither diffuse nor decompose due to ambient variations. Thus formed may be images which exhibit excellent image retention quality for an extended period of time under severe conditions such as high humidity and the like, and also exhibit excellent light fastness.

Trade marks of these resins, which are commonly available on the market, are as follows: as AS resins, GP-301 and GP-305 (TOAGOSEI CO., LTD.); as SAN resins, Tairiru-767, -769, and -783, Stylac 709, 727, 767, 769, 789 and 8707 (manufactured by ASAEI CHEMICAL INDUSTRIES CO., LTD.), Estyren AS Series (manufactured by Shin-Nittetsu Kagaku Co., Ltd.), Cevian Series (manufactured by DAICEL CHEMICAL INDUSTRIES, LTD), Litac Series (manufactured by Mitsui Kagaku 17 4334 Co., Ltd.), Sanrex SAN-C, and SAN-H, Collimate S-325, S-320, and S-315 (manufactured by Mitsubishi Monsanto Kasei. Co., Ltd.); as AAS resins, Vitax Series and Baifunen Series (manufactured by Hitachi Chemical Co., Ltd..); as AES resins, Unibright Series (manufactured by Sumitomo Nohgatac Co., Ltd.), and JSRAES Series (manufactured by Japan Synthetic Rubber Co., Ltd.); as ACS resins, ACS Resin NF Series (manufactured by Showa Denko Co., Ltd.); and the like.

Particularly preferable examples satisfying melt flow rate of at least 25g/10 ml specified in JIS K 7210 are SAN resins of Stylac 769, 789 and 8707 (manufactured by Asahi Kasei Kogyo Co., Ltd.), Litac A120, A330, A230, A930 (manufactured by Mitsui Kagaku Co., Ltd.), and ACS resins of NF 920 (manufactured by Showa Denko K.K.).

Employed as binders of the image receiving layer may be the following binders produced by blending with styreneacrylonitrile resins.

Polyvinyl butyral based resins: polyvinyl butyral resins are copolymers which are produced by allowing polyvinyl alcohol to react with vinyl butyral, which is obtained by allowing polyvinyl alcohol to react with butylaldehyde. Resins preferably have a butyral degree of the resulting polyvinyl butyral of at least 75 mole percent and a concentration of the non-saponified vinyl acetate group 18 4334 of no more than 10 mole percent due to polyvinyl alcohol employed as the raw material.

The types of binders are optionally chosen. However, in terms of image retention quality, polyvinyl acetal based resins or vinyl chloride based resins are preferred. Listed as said polyvinyl acetal based resins are polyvinyl acetoacetal resins, polyvinyl butyral resins, polyvinyl formal resins, and the like. Listed as said vinyl chloride based resins may be polyvinyl chloride resins and vinyl chloride copolymers. Listed as said vinyl chloride copolymers may be copolymers of vinyl chloride with other monomers, comprising vinyl chloride of at least 50 mole percent as monomer units. Other than the aforementioned polyvinyl acetal based resins and vinyl chloride resins, polyester based resins may be suitably employed as the thermal transfer image receiving layer. Employed as polyester resins may be, for example, polyethylene terephthalate, polybutylene terephthalate, and compounds described in Japanese Patent Publication Open to Public Inspection Nos. 58-188695 and 62-244696. Further, employed as polycarbonate based resins may be various types of compounds described, for example, in Japanese Patent Publication Open to Public Inspection No. 62-169694. Listed as acryl based resins may be, for example, polyacrylic 19 4334 esters. Employed as heat resistant resins are various types of heat resistant resins known in the art, as long as said resins exhibit good heat resistance, have neither an excessively low softening point nor glass transition point (Tg), are suitably compatible with said vinyl chloride based resins, and are substantially colorless. "Heat resistance" as described herein means that during heat resistance storage, resin themselves result in neither coloration such as yellowing nor excessive degradation of physical strength. The heat resistant resins preferably have a softening point of 30 to 200 'C, especially a Tg of 50 to 150 'C. The resins having a softening point of less than 30 OC are not preferred because during the transfer of thermally transferable dyes, an ink sheet occasionally melt-adheres to the image receiving layer. The resins having a softening point of at least 200 OC are not preferred because the sensitivity of the image receiving layer decreases. Listed as heat resistant resins, to meet the aforementioned conditions, are phenol resins, melamine resins, urea resins, ketone resins, and the like. Of these, urea aldehyde resins as well as ketone resins are preferred. Urea aldehyde resins are obtained by condensation of urea with aldehydes (mainly, formaldehyde), while ketone resins are obtained by condensation of ketone with formaldehyde.

Concrete examples include polyurethane based resins and polyester resins described in Japanese Patent Publication Open to Public Inspection Nos. 5246152, 5-64978, 4-299184, 4-43082, 5-270151; polyvinyl acetal, based resins described in Japanese Patent Publication Open to Public Inspection No. 5246151 and 5-294076; vinyl chloride based copolymer resins having an epoxy group described in Japanese Patent Publication Open to Public Inspection No. 5-246150; randomco-polycarbonate resins described in Japanese Patent Publication Open to Public Inspection No. 5-131758; polyamide resins described in Japanese Patent Publication Open to Public Inspection Nos. 4-299187 and 4-299188; water based resins comprised of hydrophobic resin composition described in Japanese Patent Publication Open to Public Inspection No. 4-347690; synthetic resins described in Japanese Patent Publication Open to Public Inspection No. 4-131287; copolymers and reaction compositions described in Japanese Patent Publication Open to Public Inspection Nos.4-135794, 615966, 58-215398, 61199997, 2-178089, 2-86494, 1-160681, 1123794, 3-126587,6-8646; acidic resins having an acid value of at least 2 described in 2-107485; mixture of water based dispersion of solvent-insoluble or solvent hardly soluble 21 4334 polyester resins with water based dispersion of thermoplastic resins other than said polyester resins described in Japanese Patent Publication Open to Public Inspection No. 6-79974; and the like.

Together employed as binders of the image receiving layer may be resins described below.

Polyolefin based resins such as polypropylene and the like, halogenated vinyl resins (polyvinylidene chloride, and the like) other than those described above, vinyl polymers (polyvinyl acetate and the like) other than those described above, polystyrene based resins, polyamide based resins, copolymer based resins of olefin such as ethylene, propylene, and the like with other vinyl monomers, ionomers, cellulose based resins such as cellulose diacetate, polyurethane resins, polyimide resins, epoxy resins, and the like.

In the present invention, the image receiving layer comprises thermally diffusible dyes as well as metal ion containing compounds (hereinafter referred to as metal source) capable of forming metal chelates, other than binders.

In the present invention, the metal source is incorporated into the image receiving layer, while employed as dyes (hereinafter referred to as postchelate dye), which are incorporated into the dye-containing region of the ink 22 4334 sheet, are those capable of forming chelates with the metal source. By so doing, exhibited may be excellent effects in higher density of transferred images, higher image retention quality, and particularly further minimization of bleeding.

Listed as metal sources are inorganic or organic salts of metal ions as well as metal chelates. of these, salts of organic acids and chelates are preferred. Listed as metals are univalent and polyvalent metals belonging to Group I through VI in the Periodic Table. Of these, Al, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Sn, Ti, and Zn are preferred, and Ni, Cu, Cr, Co, and Zn are particularly preferred. Cited as specific examples of the metal sources are aliphatic carboxylic acid salts of Ni2% CU2,' Cr 2,' C02,, and Zn 2+ with acetic acid, stearic acid, and the like, and aromatic carboxylic acid salts of said ions with benzoic acid, salicylic acid, and the like. Further, chelates represented by the general formula (M) shown below are particularly preferred because they are stable in the image receiving layer and are substantially colorless.

General Formula (M) IM (Q1). (Q2) y (Q3) P+ (L-) p wherein M represents a metal ion, and is preferably Ni2+, CU2+, Cr 2% Co 2+ or Zn2+. Q1, Q2, and Q3 each represents a coordination compound which is capable of forming a coordinate bond with the metal ion represented by M, and may 23 4334 bethe same or different. These coordination compounds may be selected from those described in, for example, "Chelate Kagaku (Chelate Science) (5) " (Nankodo). L- represents an organic anionic group, and specifically, listed may be a tetraphenylboron anion, an alkylbenzenesulfonic acid anion, and the like. x represents 1, 2, or 3, y represents 1, 2, or 0, and z represents 1 or 0. These are determined depending on tetradentate coordination or hexadentate coordination of the chelate represented by the general formula (M), or depending on the number of ligands of Q1, Q2, and Q3 P represents 1 or 2. Listed as specific examples of this type of metal source may be compounds described in U.S. Pat. No. 4,987,049.

The added amount of metal sources is preferably between 5 and 80 percent by weight with respect to the binder of the image receiving layer, and is more preferably between 10 and 70 percent by weight. The excessive amount of metal sources is not preferred because the tint of metal sources appears on the tint of the background of the image receiving element.

When acrylic resins which are comprised of styrene and acrylonitrile as indispensable components and further have a melt flow value of at least 20g/10 minutes, specified in JIS K 7210, are employed as the binder of the image receiving layer, image density increases. On the contrary however, 24 4334 thermal melt-adhesion with the ink sheet tends to occur. In order to overcome this problem, releasing agents are preferably incorporated into the image receiving layer. Mainly listed as methods to incorporate the releasing agents into the image receiving layer are one in which various releasing agents are incorporated into the image receiving layer, and the other in which a layer having high releasability (of a releasing layer) is newly applied onto the image receiving layer. Among these, it is preferred to provide the releasing layer on the image receiving layer so as to obtain the releasability in a small amount of releasing agents which do not adversely affect the other performance.

The releasing agent enhances peeling properties of the ink layer of the ink sheet from the image receiving layer of the image receiving sheet. Listed as such releasing agent are sold waxes such as silicone oil (including those called silicone resins), polyethylene wax, polypropylene wax, amide wax, Teflon power, and the like, fluorine compounds, silicon compounds, and composites thereof, fluorine based or phosphoric acid ester based surface active agents, coupling agents, long chain alkyl compounds, polyoxyalkylpolyols, and the like. of these, silicone oil is preferred, and one having at least one of alkyl group, alkylene group and styryl 4334 group in the structure thereof is preferred in view of releasing ability and other property.

The coating amount is preferred so as to obtain a dry layer thickness of 0.1 to 2.0 g/m 2 when provided as a releasing layer, and 0.1 to 40 % by weight to solid component in case of adding to the image receiving layer.

The thermal transfer image receiving material (2) of the present invention comprises an image receiving layer having thereon a releasing layer containing a silicon compound having at least one of an alkyl group, an alkylene group, and a styryl group in its layer fabrication. The silicone oil listed in the aforementioned thermal transfer image receiving material (1) is preferred as the releasing agent contained in said releasing layer. By employing the silicone oil, the following effects are obtained. When a protective layer comprising acrylic resins is provided, the releasability from the ink sheet is improved and the surface durability is enhanced. When stored under severe conditions for an extended period of time, neither discoloration of images nor bleeding results.

In the present invention as described in item 10, an ink sheet comprising thermally diffusible dyes which are capable of forming a chelate compound with a metal ion containing compound is faced with the image receiving layer 26 4334 of the thermal transfer image receiving material (2), and heated imagewise in accordance with recording signals so that an image is formed upon transferring the dyes in said ink sheet onto the receiving layer. Thermal transfer recording is completed upon providing a transparent protective layer onto the resultant image surface.

It is known. in the art that providing a transparent protective layer (hereinafter, occasionally referred to as a protective layer) on the image surface, improves the image retention quality as well as durability, specifically physical durability to counter the following: when stored in an album with transparent sleeves, and the like; when rubbed with a plastic eraser; when brought into contact with any substance (especially substance comprising plasticizers), transferring the dyes into such a substance and resulting in image bleeding; when water, juice, alcoholic beverage, coffee, and the like are spilled on the image, and subsequently wiped or touched with fingers, fading of dye tints due to extraction; and the like.

Employed as a means to transfer the protective layer are a heating means such as a heated roller, a heat press, a thermal head, a laser beam, and the like, with which said protective layer is transferred. The heating means may be employed which are the same as those during dye transfer, or 27 4334 another heating means may be provided for the transfer of the protective layer.

In the present invention, supports employed in the protective layer region are not particularly limited, and those, which have been employed for conventional ink sheets for heat diffusible dyes, are employed. Concrete examples of the preferable support include thin paper such as condenser paper, glassine paper and paraffin paper, high heat resistant polyester such as polyethyleneterephthalate, polyethylenenaphthalate, polybutyleneterephthalate, polyphenylenesulfide, polyetherketone and polyethersulfone, stretching or non-stretching treated plastic film such as polypropylene, polycarbonate, cellulose acetate, polystyrene derivatives, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polymethylpentene and ionomer, and laminated material of these. Thickness of the support is optionally selected to obtain adequate strength, heat transition, heat resistance etc., corresponding to the employed materials, and usually is 1 to 100 lam.

In the present invention, the protective layer region is comprised of a single resin layer or a plurality of resin layers. Employed as resins in said resin layer may be those conventionally known in the art. However, those, which enhance durability as well as image retention quality, are 28 4334 preferred. Specifically are employed homopolymers such as vinyl chloride based resins, polyester based resins, polycarbonate base resins, acryl based resins, styrene resins, acrylonitrile resins, polyvinyl acetal based resins, vinyl alcohol based resins, polyamide based resins, or copolymers thereof. of these, acrylic resins comprising acrylic acid, methacrylic acid, and derivatives thereof, copolymers of styrene resins, and acrylonitrile resins are preferred. Specifically, the aforementioned acrylic resins comprising styrene and acrylonitrile resins may be employed.

Further, the protective layer may comprise conventional additives known such as thermal plastic resins, thermally fusible compounds, UV absorbers, antioxidants, light stabilizers, plasticizers, and the like. Particularly, it is preferred to employ at least one of UV absorbers, antioxidants and light stabilizers.

As the UV absorbers, those which function to absorb ultraviolet rays incident to dye images and are capable in thermal transfer are practiced. For example,- there can be employed compounds described in JP-A-Nos. 59158287, 6374686, 63-145089, 59-196292, 62-229594, 63-122596, 61-283595, 1204788, etc. and compounds known in the art as those which improve the durability of images in photography and the other image recording materials. Concrete examples include 29 4334 salicylic acids, benzophenones, benzotriazoles and cyanoacrylates. These are in market with trade names of Tinuvin P, Tinuvin234, 320, 327, 328, 312 and 315 (manufactured by Ciba Geigy Corp.) Sumisorb-110, 130,140, 200, 250, 300, 320, 340, 350, and 400 (manufactured by SUMITOMO CHEMICAL CORP., LTD.), Mark La-32, 36 and 1413 (manufactured by Adeka Argas CORP., LTD.) A pendant polymer having benzopheneone derivatives at side chains is also employed preferably. Inorganic fine particles and dispersion of super fine metal oxide powder may be also employed. Example of the super fine metal oxide powder dispersion includes those prepared by employing the super fine zinc oxide powder, super fine titanium oxide powder etc. water or alcohol mixture or various oleophilic dispersion medium and dispersing agent such as a surfactant water soluble polymer, polymer soluble in solvent etc.

The antioxidants can include those described in JP-ANos. 59-182785, 60130735, 1-127387 and compounds known in the art which improve the durability of images in photography and the other image recording materials. Concrete examples include primary anti-oxidant such as phenols, monophenols, bisphenols, amines, secondary anti-oxidant such as sulfur compounds and phosphor compounds. These are in market with trade name of Sumilizer BBM-S, BHT, BP-76, MDP-S, GM, WX-R, 4334 BP-179, GA, TPM, TP-D and TNP (manufactured by SUMITOMO CHEMICAL CORP., LTD.) Irganox-245, 259, 1010, 1035, 1076, 1081, 1098, 3114 (manufactured by Ciba Geigy CORP., LTD.), Mark Aq-20, AO-30, and AO-40 (manufactured by Adeka Argas Chemical Corp.) The light stabilizer includes compound described in JPA-Nos. 59-182787, 63-74686, 63-145089, 59-196292, 62-229594, 63-122596, 61-283595 and 1- 204788, and compounds known in the art which improve the durability of images in photography and the other image recording materials. Concrete example includes hindered amine compound such as Tinuvin 622LD, 144, Chimassob 944 LD (manufactured by Ciba Geigy CORP., LTD.), Sanol LS-770, Ls-765, LS-292, LS-2626, LS-114, LS-774 (manufactured by SANKYO CO., LTD. ), Mark LA-62, LA-67, LA-63, LA-68, LA-82 and LA-87 (manufactured by Adeka Argas Chemical Corp.) available in the market.

A compound enhancing peel ability may be incorporated in the protective layer or a layer provided between the protective layer and the support as an independent layer.

Dye fixer is preferably incorporated in at least one layer constituting protective region for the purpose of accelerating reaction of dye precursor unreacted in the image receiving layer in case that reactive image receiving layer is employed. For example, active hydrogen compound may be 31 4334 incorporated in the protective layer when the above mentioned specific structure dye having reaction group, and a metal chelate compound may be incorporated the protective layer when the post chelate dye is employed in the side of ink sheet.

Though the dye fixer may be incorporated in any layer, the content is restricted because various problems are caused by that the dye precursor and/or dye fixer transfers to back side of the facing ink sheet or film material during storage of the ink sheet in case that the layer containing the dye fixer is provided at outermost. For example, in case of preparation of an ink sheet in a form of providing a protective region after ink layers in sequential frame order dye precursor transfers slightly to back side of faced ink sheet from the ink layer by heat or pressure during preservation after coating in a form of large roll. The dye fixer in the outermost layer of the protective region reacts at the portion contacting the area to which the dye precursor transfers, and the reacted dye transfers when the protective layer transfers at the time of printing whereby a phenomenon called "kick back", that is undesirable color appearing within printing region, occurs. Thus image quality degrades markedly. Dye fixer also transfers to the back side in addition to the dye precursor in the similar way, and it is 32 4334 considered to cause baneful influence making thermal head which contacts with back side of the ink sheet directly contaminated at the time of printing. The latter phenomenon may occur in case of preparation of a single sheet having the protective region only on the support but not ink containing regions sequential frame order. The dye fixer is preferably incorporated in other than the outermost layer among the layers constituting protective region from the view point mentioned above.

The amount of dye fixer to be added, varying depending on the species of dye precursor employed in combination, preferably is 0.1 to 10 % of solid component in case of incorporating in the outermost layer., and 0.5 to 50 % of solid component in the layer in case of incorporating in a layer other than the outermost layer. Further, preferably 0.1 to 20 mass % and more preferably 0.5 to 10 mass % of the solid component in the whole layers in case of incorporating in the protective region.

It is preferable that the dye fixer is incorporated in the image receiving layer of the image receiving material.

The protective region can be prepared by coating a coating composition, which is prepared by dispersing or dissolving components in solvent, onto a surface of the support in, for example, gravure printing method, and drying 33 4334 it. Thickness of the protective layer is 0.5 to 20 pm, preferably 0.3 to 10 m in total.

The protective region may be provided to appear consequent to dye providing region of the ink sheet in sequential frame order, or may be provided as separated monocolor rolls with other color.

The thermal transfer image recording material is composed of at least a support and an image-receiving layer formed on the support.

The supports for the image-receiving element may include, for example, various kinds of paper such as paper, coat paper and synthetic paper (composite material in which paper is laminated on polyethylene, polypropylene, polystyrene, etc.); various kinds of plastic films or sheets such as vinyl chloride series plastic sheet, ABS resin sheet, polyethylene terephthalate base film, polyethylene naphthalate base film, etc.; film or sheet made of various kinds of metals; film or sheet made of various kind of ceramics, etc. It is preferred to employ the paper mentioned above in combination in case that the support of the image receiving layer comprises a porous resin layer. The paper employed as the support preferably is stiff one. Particularly high quality paper having weight of 110 to 200 g/M 2 and thickness of 90 to 180 m is preferable.

34 4334 It is preferred to provide a coating layer of aqueous dispersion liquid of resin on the opposite side to the side having image receiving layer, or a backing resin layer having higher tensile elastic modulus than that of the porous resin layer in case that the paper is employed in combination with porous resin layer as the support of the image receiving sheet in the present invention.

The aqueous dispersion liquid of resin is liquid containing a resin dispersed in water as fine particle state. A method of progressing polymerization reaction while monomer is made to be dispersed in water is employed generally to prepare the aqueous dispersion liquid of resin, wherein a surfactant is employed to disperse the monomer. Preferable surfactant is an anionic surfactant. It is preferable to contain a polymerization initiator such as radical polymerization initiator in dispersant. Polypropylene, polyurethane, saturate polyester, polyacrylic ester, polyacrylonitrile, polystyrene, alkyd resin, SBR, ABS resin are cited as the preferable examples of the resin.

A hydrophobic binder is preferably employed for a coating composition to provide an aqueous dispersion coating layer in view of preventing curling. The hydrophobic binder is preferably a hardening resin such as a thermal hardening resin, electron ray hardening resin, UV ray hardening resin.

4334 It is advantageous in reducing curl variation, particularly controlling curl variation at high temperature and high moisture by employing the hardening resin. The coating layer preferably has linear tensile strength of more than 100 kg/cm 2 in a dry state. The thickness of the coating layer is preferably 2 to 60 im.

It is preferred to incorporate inorganic fine particles in the aqueous resin dispersion coating layer to give the image receiving layer writing ability. Porous silica, alumina, clay, talc, diatom earth, calcium carbonate, baked kaolin, titania, zinc oxide and satin white are cited preferable as the preferable examples of the inorganic fine particles. Ratio of the resin to the inorganic fine particles is 80/20 to 40/60 (resin/ inorganic fine particles) by weight in a dry state, and the amount to be contain is 20 to 60 % with reference to weight of solid parts of the coating layer.

It is preferred to incorporate an antistatic agent in the aqueous resin dispersion coating layer as it improves conveying characteristics at the printing time. Cationic surfactant, anionic surfactant, nonionic surfactant, polymer antistatic agent, electric -conductive fine particle compound, and, in addition thereto, compounds described in "11290 Chemical Articles" pages 875 to 876, Kagaku Kogyo Nipposha, 36 4334 are widely employed as the antistatic agent. The preferable examples of the antistatic agent are carbon black; metal oxide such as zinc oxide, titan oxide and stannic oxide; and electro-conductive fine particles such as semiconductor fine particles, and among these, elec tro -conductive fine particles are preferable as they are not release from the coating layer of the antistatic agent and give stable antistatic effect independently from environment change. Amount of the antistatic agent to be contain is 3 to 30 % of solid parts of the coating layer.

Various active agents, releasing agent such as silicone oil and fluoride resins may be added to the aqueous resin dispersion coating layer so as to give coating ability and releasing ability. Coating methods such as roll coating, wire bar coating, air knife coating etc. are applied.

It is preferred to incorporate in the support white pigment such as titan white, magnesium carbonate, zinc oxide, barium sulfite, silica, clay and calcium carbonate to enhance the clearance of the image when the support is composed of a material other than metal or ceramics, particularly is composed of synthesized paper. The adequate thickness of the support is usually 20 to 1000 jim, preferably 20 to 800 im.

It is preferred to have a porous resin layer as a support or one or more layers provided on the support in the 37 4334 present invention. The porous resin layer is a layer containing void such as air bubble. To incorporate the bubble certain resin and a substance immiscible in the resin are mixed, the mixture is extruded and stretched. or a thermally expandable hollow particle or a capsule-shaped hollow resin particle can be used. Moreover, a decomposition type foaming agent, such as dinitropentamethylenetetramine, diazoaminobenzene, azobisisobutylnitryl and azodicarboamide, which generates a gas such as oxygen, carbon dioxide gas or nitrogen, by heating. The foams contained in the layer are preferably independent foams from the viewpoint of ability of cushion and heat insulation, for example, that described in JP- A-No. 6-270559 is preferable. Although an adhesive may be contained in the foam-containing layer, a primer layer may be provided between the support and the foam-containing layer to enhance the adhesion between them. A primer layer described in JP-A-No. 5-270152 can be used such the primer layer. It is preferred to make the specific gravity of 0.3 to 0.8 by the processing to contain air bubbles in the resin, in comparison with the resin containing no air bubbles as itself.

Resin to form porous resin layer is preferably polypropylene or more preferably polyester, in view of glossiness of the image and curling. The polyester referred 38 4334 here is a polymer obtained by condensation polymerization of diol and dicaboxylic acid. As the examples of the dicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid dinaphthalenecaboxylic acid etc. are cited. As the examples of diol, ethylene glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dimethanol etc. are cited. Polyethyleneterephthalate (PET) is preferable among the polyester.

The porous resin layer preferably has a thickness of 20 to 200 jim, and specific gravity of 0.5 to 1.0. It may be formed by a single layer, and preferably, may be multi-layer structure having different specific gravity in view of preventing curling and giving cushion property.

Simultaneous extrusion stretching is preferable as the preparation method of porous resin layer.

The image-receiving layer is not specifically restricted as far as it accepts a dye which is diffused upon heating from the ink layer of the ink sheet. The imagereceiving layer is basically composed of a binder and various additives.

As a method to form the image-receiving layer on the surface of the support, a coating method can be illustrated in that a coating liquid is prepared by dispersing or dissolving components forming the imagereceiving layer and 39 4334 coat dried on the surf ace of the above-mentioned support, or a laminating method can be illustrated in that a mixture containing components forming the above-mentioned imagereceiving layer is laminated on the surface of the support employing melt extrusion. The thickness of the imagereceiving layer formed on the surface of the support is usually in the range of from 0.5 to 50 lam and preferably from 1 to 2 0 jim.

In forming the image receiving layer various resins mentioned above may be cross-linked or hardened utilizing the reactive group thereof by radiation, heat, moisture or a catalyst, when the resin has no reactive group the reactive group can be given. In such the case, a radiation reactive monomer such as an epoxy compound or an acryl compound and a cross-linking agent such as an isocyanate compound may be used. Such the monomer and the cross-linking agent may be added into the image receiving layer directly or in a form of closed in a microcapsule.

The above mentioned anti-oxidant, UV absorber, stabilizing agent against light, sensitizer such as a plasticizer and heat-solvent, filler and pigment etc. may be added to the image receiving layer.

As the filler, an inorganic and an organic particle can be used. Examples of the inorganic particle include silica 4334 gel, calcium carbonate, titanium oxide, acid clay, active clay, and alumina. Examples of the organic particle include a fluoro resin particle, a guanamine resin particle, an acryl resin particle and a silicone resin particle. These inorganic or organic particles are preferably added in an amount of from 0.1% to 70% by weight even though the amount is varied depending on the specific gravity of the particle. Titanium white, calcium carbonate, zinc oxide, barium sulfate, silica, talc, clay, kaolin, acid clay, and active are usable as the pigment.

A phthalate such as dimethyl phthalate, dibutyl phthalate, dioctyl phthalate and didecyl phthalate, a trimellitate such as octyl trimellitate, isononyl trimellitate and isodecyl trimellitate, a pyromellitate such as octyl pyromellitate, and a adipate are usable as the plasticizer.

The adding amount of the plasticizer is ordinary within the range of from 0.1% to 30% by weight of the binder of the image receiving layer since an excessive addition. of the plasticizer causes degradation in the storage ability of image.

A slippery backing layer may be provided on the back surface of the image receiving sheet in addition to the aqueous dispersion coat layer of the above mentioned resin.

41 4334 A resin to be used such the purpose is preferably one hard to be dyed. Examples of such the resin include an acryl resin, a polystyrene resin, a polyolefin resin, a polyamide resin, polybutyral, polyvinyl alcohol, and a cellulose acetate resin. An amorphous polyolefin resin described in JP- A-No. 7-186557 is also usable. other than the above-mentioned, a polyvinylbutyral resin, a melamine resin, a cellulose resin and an acryl resin each hardened by a hardening treatment by a chelate, an isocyanate or radiation are also preferable. Examples of the resin available in the market include acryl resins BR85, BR80 and BR113 manufactured by Mitsubishi Rayon Co., Ltd., amorphous polyolefin resins APL6509, 130A, 291AS, and 15OR manufactured by Mitsubishi Sekiyu Kagaku-Kogyo Co., Ltd., and Zeonex 480, 250 and 480S, manufactured by Nihon Zeon, polyvinylbutyral resin 3000-1, manufactured by Denki Kagaku-Kogyo Co., Ltd., polyvinyl alcohol resins manufactured by SMR-20H, SMR-20HH, C-20, C- 10, MA-23, PA-20 and PA-15, manufactured by Shin-Etsu Kagaku-Kogyo Co., Ltd., acetyl cellulose resins L-30 and LT-35, DAICEL CHEMICAL INDUSTRIES, LTD, melamine resin Saimel 303 manufactured by Mitsui Siad, etc., to which the examples are not restricted.

An organic and/or inorganic filler may be contained in at least one layer provided on the back surface of the image receiving sheet to improve the suitability for automatic 42 4334 sheet supplier. As the f iller, polyethylene wax, bisamide, nylon, acryl resin, cross-linked polystyrene, silicone resin, silicone rubber, talc, calcium carbonate and titanium oxide are usable without specially restricted.

The center line average surface roughness Ra of the backing layer surface is preferably from 0.5 pm to 2.5 jim, and the average number of protrusion per unit area is preferably 2,000 to 4,500 per square millimeter.

Such the property on the surface of the backing layer can be prepared, other than the conditioning by the filler, by a method in which the surface of a cooling roller having such the surface condition is used when the resin is coated by extrusion coating addition so as transfer the condition of the roller surface to the resin layer surface.

An interlayer may be provided between the slippery backing layer and the support sheet to raise the adhesiveness between these layers. The interlayer is preferably formed by a reaction hardened type resin.

A thermally hardenable and/or ionized irradiation hardenable resins described in JP-A-No. 6-255276 are preferably used as the reaction hardened type resin.

Such the interlayer may be provided between the support and the image receiving layer.

43 4334 The image receiving layer may be subjected to a matting and/or glossiness controlling treatment by the method described in JP-A-No. 4-241993.

A transparent heat absorbing substance may be contained in the image receiving layer and/or a layer adjacent to that. Heat accumulated near the heat absorbing substance expands the image receiving layer and the dye is effectively transferred into the image receiving layer.

In the present invention, the ink sheet is fundamentally composed of a support and an ink sheet provided thereon. The ink sheet comprises at least a dye-containing region containing thermally transferable post chelate dye and a region containing substantially no dye. The "region containing substantially no dye" means that the region does not contain a dye of which quantity and/or quality does not degrade the image quality formed by thermal transfer.

As the support for the ink sheet, material which exhibits good dimensional stability and withstands heat at recording with a heat- sensitive head can be employed.

The ink layer at the dye-containing region is preferably composed of at least a thermally transferable post chelate dye and a binder.

As the binder of the ink layer, there can be illustrated, for example, cellulose series resins such as a 44 4334 cellulose addition compound, cellulose ester, cellulose ether, etc., polyvinyl acetal resins such as polyvinyl alcohol, polyvinyl formal, polyvinyl acetoacetal, polyvinyl butyral, etc., vinyl series resins such as polyvinylpyrrolidone, polyvinyl acetate, polyacrylamide, styrene series resins, poly (meta) acrylic acidseries esters, poly (meta) acrylic acid, (meta)acrylic acid copolymer, rubber series resins, ionomer resins, olefin series resins, polyester resins, etc. Of these resins, the polyvinyl butyral, polyvinyl acetoacetal or cellulose series resins having excellent preservation quality are preferred.

As the binder of the ink layer, resins mentioned below can be employed. In Japanese Patent Publication (JP-B) No. 5-78437 there are illustrated reaction products of isocyanates with compounds having an active hydrogen selected from polyvinyl butyral, polyvinyl formal, polyesterpolyol and acrylpolyol, the above-mentioned reaction products in which isocyanates are diisocyanates or triisocyanates and the above-mentioned reaction products of 10 to 200 weight parts for 100 weight parts of the active hydrogen-containing compound; organic solvent-soluble high polymer in which intramolecular hydroxide groups in a natural and/or semisynthesized water-soluble high polymer are esterified and/or urethanized, the natural and/or semi -synthesized water- 4334 soluble high polymers; cellulose acetates having a degree of acetylation of 2.4 or more and degree of total replacement of 2.7 or more which are described in JP-A-No. 3-264393; vinyl resins such as polyvinyl alcohol (Tg = 85 OC), polyvinyl acetate (Tg = 32 OC), vinyl chloride/vinyl acetate copolymer (Tg = 77 OC), etc. polyvinyl acetal series resins such as polyvinyl butyral (Tg = 84 OC), polyvinyl acetoacetal (Tg 110 OC), etc. , vinyl series resins such as polyacrylamide (Tg 165 OC), polyester resins such as aliphatic polyester (Tg 130 OC), etc. and the like; reaction products of isocyanates with polyvinyl butyral in which the weight of contained part of the vinyl alcohol is from 15 to 40 percent, described in JP-A-No. 7-52564, the above-mentioned reaction products in which the above-mentioned isocyanates are diisocyanates or triisocyanates; phenylisocyanate-modified polyvinyl acetal resins of the formula I described in JP-A-No. 7-32742; compounds obtained by hardening compositions consisti ng of one of isocyanate reactive cellulose or isocyanate reactive acetal resin, and one resin selected from isocyanate reactive acetal resin, isocyanate reactive vinyl resin, isocyanate reactive acrylic resin, isocyanate reactive phenoxy resin and isocyanate reactive styrol resin, and a polyisocyanate compound, described in JP-A- No. 6-155935; polyvinyl butyral resins (having preferably molecular weight of 60,000 or more, 46 4334 glass transition temperature of 60 OC or higher, more preferably 70 OC or higher and 110 OC or lower, weight percent of vinyl alcohol part of 10 to 40 percent of polyvinyl butyral resin, preferably from 15 to 30 percent); acryl-modified cellulose series resins, as the cellulose series resins, cellulose series resins (preferably ethy1cellulose) such as ethylcellulose, hydroxyethylcellulose, ethylhydroxycellulose, hydroxypropylcellulose, methylcellulose, cellulose acetate, cellulose butyrate, etc.

The above-mentioned various binders are employed individually or in combination of two or more thereof.

The dye-containing region can be one which contains two or more of dyes different in hue. For example, embodiments are enumerated in that the dyecontaining region is composed of an yellow dye-containing region, a magenta dye-containing region and a cyan dye-containing region, and a region containing no dye is arranged next these dye-containing regions; the dye-containing region is composed of a black dye-containing layer and the a region containing no dye is formed next the above-mentioned region and the dye-containing region is composed of the yellow dye-containing region, a magenta dye-containing region, a cyan dye-containing region 47 4334 and a black dye-containing region and a region containing no dye is f ormed next these dye-containing regions.

The "black dye" described herein includes an embodiment in which in addition to black dyes, black hue is prepared by combination of two or more of dyes other than the black dye, for example, an yellow dye, a magenta dye and a cyan dye are mixed to form black hue.

The hue of a dye prior to the chelation and after the chelation may be the same or very different. Yellow of a yellow dye, magenta of a magenta dye, cyan of a cyan dye and black of a black dye described herein mean the hue of the dye after the chelation.

An example of the arrangement of the ink layer on the ink sheet is explained below with reference to the drawing. Fig. 1 is plan showing a model of an example of arrangement of a dye-containing region and a no dye-containing region provided on the ink sheet.

Fig. 1 shows one example of an embodiment in which a dye-containing region is composed of a yellow dye-containing region, a magenta dye- containing region and a cyan dyecontaining region and a metal source - containing source is formed next those dye-containing regions. In Fig. 1, an ink sheet 1 is provided with each of ink layers in order of an yellow dye-containing region 1Y, a magenta dye-containing 48 4334 region 1M and a cyan dye-containing region 1C and next those dye- containing regions, is provided a metal source -containing layer (post treatment region) la which contains no thermally transferable dye and contains a metal source and a combination of those arrangements is repeated.

Known various compounds are usable as the postchelating dye without any limitation as long as the dye can thermally transfer. In concrete, cyan dyes, magenta dyes and yellow dyes described in, for example, described in JP-A-Nos. 59-78893, 59-109349, 4-94974, 4-97894 and are usable.

Among these dyes, one capable of forming a di-dentate chelate with the metal source is preferable used. Examples of such the dye are ones represented by the following Formula 1.

Formula 1 1 R2 R3 7 1 X=" b_-Y n In the above formula, X is an group of atoms having a group or an atom each a capable of forming a di- or more dentate chelate, Y is a group of atoms necessary to form an aromatic carbon ring or heterocyclic ring, R1, R2 and R3 are each independently a hydrogen atom, a halogen atom or a monovalent substituent. n is 0, 1 or 2. Y is preferably a group 49 4334 of atoms necessary to form a 5- or 6-member aromatic carbon ring or heterocyclic ring, which may have a substituent.

The group represented by X is preferably one represented by the following Formula 2.

Formula 2 Z In the above formula, Z is a group of atoms necessary to form an aromatic nitrogen-containing heterocyclic ring having a substituent containing a nitrogen atom capable of forming a chelate.

Examples of such the ring include benzene, pyridine, pyrimidine, furan, thiophene, thiazole, imidazole and naphthalene. These rings each may be condensed with a carbon ring such as a benzene ring or a heterocyclic ring such as a pyridine ring.

Examples of the substituent of such the ring include an alkyl group, an aryl group, an acyl group, an amino group, a nitro group, a cyano group, an acylamino group, an alkoxyl group, a hydrox-yl group, an alkoxycarbonyl group and a halogen atom. These group each may have a substituent thereof.

Example of the halogen atom represented by R1, R2 or R3 include a fluorine atom and a chlorine atom, and those of a 4334 mono-valent substituent represented by R1, R2 or R3 include an alkyl group, an alkoxyl group, a cyano group and an alkoxycarbonyl group.

Groups represented by the following Formula 3, 4, 5 or 6 are preferable as the group represented by X=.

Formula 3 Formula 4 R4 R4 N- N- N N "' N _N IN -,N R5 Q -1 If Formula 5 Formula 6 Q R4 N _N N_ J-.,N--/% % 0 R4 In the above-mentioned formulas, R4 and R5 are each a hydrogen atom, a halogen atom such as a fluorine atom, chlorine atom and a bromine atom, or a mono-valent substituent such as an alkyl group, an aryl group, an acyl group, an amino group, a nitro group, a cyano group, an acylamino group, an alkoxyl group, a hydroxyl group, and an alkoxyca.rbonyl group.

51 4334 Examples of the post-chelating dye are shown.

N(CH3)2 -(2) N(CH3)2 H H Y,H (t)C4 H9,11 _.r N, MC4H9 N N N I N-N N N N(CH3)2 N(CH3)2 (3) (4) CH3 CH CF3 N, N N N-N N%- N CH3 N I CH3 (5) N(CH3)2 (6) N(CH3)2 N C' H CH N, MCA N, N N Y, N- N-N--i N N, N CH3 I CH3 52 4334 (7) OCH 3 I I q H MC4H9 CH N, (t)C4H9yrN- N N N-N-')l N-N--j N (9) OH (10) CH CH MCA Yly N, N MCA N, N N N N(C2H5)2 (12) N S - CH CH3,rJ,,rN 'N CH MC4H 9 - N,, N N N N 53 4334 (13) N(C2HS)2 (14) N(C2HS)2 C H43 CH CH CH N CH3 CH W 3 N 3 N N N I I N N H3 CH3 N(C2H5)2 N(C2HS)2 (16) s CH3 CH 34 CH N F CH3 N N N N c 3 (17) N(CH3)2 (18) OCH3 CH CH CH CH CH3 CH 3 N MCA N, N N N N 3 N CH 54 4334 (19) N(CH3)2 (20) N(CH3)2 I I CH CH CH N N CH3 3 CH3 I - N XL-N NHCOCF3 4N I CH3 I N N CH3 CH3 (21) (22) a0 1 0 N N a--NN I =CH---,&N(CH3)2 I =CH--N(CH3)2 N N CH3 CN (23) (24) N 0 0 N N N I = CH N(CH3)2 =CH--&N(C2HS)2 N N CH3 CN 4334 (25) (26) C2Hs C4HS C N ', I ' OCH 3 CH3 H CH (t)C4Ha N C4H N-, 9y"Y N N-N-f CH3 (27) N H Br-c-\-N=N N(C2H5)2 (28) OH N=N N)a S CH3 OCA, Those disclosed in Japanese Patent Application No. 1160123 are employed preferably in addition to these.

The post-chelating dye is usually used in an amount of from 10% to 80% by weight of the whole compositions contained in the area containing the post chelate dye, even though the content of the post-chelating dye may be changed depending on 56 4334 the property of the dye, the solubility of the dye in the binder or the purpose of use.

As a metal source to be contained in the metal source containing area of the ink sheet, the compound described as the metal source to be contained in the image receiving layer mentioned above. Quantity of metal source in the metal source containing area of the ink sheet is, 1 to 100 mass %, preferably 10 to 50 mass % of binder amount in case that the image receiving layer contains metal source, and 10 to 250 weight %, preferably 50 to 150 mass % of binder amount in case that the image receiving layer does not contain metal source. It is not preferable as the image is spoiled caused by that post chelate dye is adsorbed to the metal source transfer layer during the storage in a roll state when the metal source in the ink sheet is in excess.

Various kinds of additive other than the abovementioned may be optionally further added to the dye containing region and metal source containing region of the ink sheet. The additives include the foregoing mold releasing agent such as a silicone compound including reaction hardenable type, a silicone-modified resin, a fluorine resin, a surfactant and a wax, a filler such as a fine metal powder, a silica gel, a metal oxide, carbon black, and a resin powder, a hardening agent capable of reacting 57 4334 with the binder, for example, a irradiation reactive compound such as an isocyanate compound, an acryl compound and an epoxy compound.

Another layer may be further provided in addition to the two layers construction of the support of the ink sheet. For example, an over-coat layer may be provided on the surface of the ink layer to prevent adhesion or blocking with the image receiving layer caused by fusion and transfer of dye to the back side of another sheet.

A subbing layer may be provided on the support of the ink sheet for improving an adhesion ability of the support to the ink layer and for preventing transfer of the dye precursor to the support. Furthermore, an anti-sticking layer may be provided on the back side, opposite to the ink layer provided side, for preventing fusion adhesion and sticking of the thermal head to the support and formation of a wrinkle of the support. The thickness of the over-coat layer, the subbing layer and the antisticking layer are each ordinary from 0.1 pm to 1 pm.

The ink sheet can be manufactured in such a way that an ink layerpreparing coating liquid is prepared by dissolving or dispersing the above-mentioned various compositions composing an ink layer to a solvent and the resulting is coated on the surface of a support for the ink sheet 58 4334 employing, for example, a gravure printing process and dried. The thickness of the formed ink layer is generally in the range of from 0.2 to 10 im and preferably in the range of from 0.3 to 3 pm.

An anti-static function may be given to the image receiving sheet and/or the ink sheet. Known technology can be applied to give the anti-static function. Namely, known electric conductive substances such as a fine powder of metal, metal oxide and carbon, organic compounds so called antistatic agent such as an anionic, cationic, amphoteric and nonionic surfactant and a polysiloxane compound, fine powder of electron inorganic conductive substances such as a fine powder of titanium oxide, zinc oxide, tin oxide or indium oxide subjected to a doping treatment in which the powder is mixed with an impurity and baking to introduce an irregularity into the crystal lattice for raising the electron conductivity are usable. The foregoing electric conductive substances may be added into at least one of the layers of the image receiving sheet and/or the ink sheet, or a layer containing the electric conductive substance may be provided. of course, a combination of the above-mentioned layers is preferably used.

The resin to be the binder of the electric conductive layer is preferably a thermally hardenable resin such as a 59 4334 thermally hardenable polyacrylate resin and a polyurethane resin, or a thermoplastic resin such as a poly(vinyl chloride) resin, a polyvinylbutyral resin and a polyester resin. The ratio of the binder to the electro conductive substance is preferably decided so that the surface intrinsic resistance of the electric conductive layer after coating and drying or hardening is not more than 1 x 1010 n-cm.

The electric conductive liquid thus prepared can be coated by an ordinary coating method such as coating by a blade coater or a gravure coater, and a spray coating method.

When the electric conductive layer is provided on the support to give the anti-static function, it is preferred to coat an aqueous solution of the anti-static agent on the support or the electron conductive inorganic fine powder dispersed in a synthesized resin emulsion, a synthesized rubber latex or an aqueous solution of a water-soluble resin on the support and to dry the coated layer. An emulsion of a polyacrylate resin or that of a urethane resin is usable as the synthesized resin emulsion, and a latex of methyl methacrylate-butadiene rubber or that of styrene- butadiene rubber is usable as the synthesized rubber latex. An aqueous solution of poly(vinyl alcohol) resin, polyacrylamide resin or starch are usable as the aqueous solution of water-soluble resin. The electric conductive layer may be formed more 4334 simply by spraying an aqueous solution of the anti-static agent.

In another embodiment, an anti-static layer composed of an acryl resin and an epoxy resin described in JP-A-No. 852945 may be used for rising the adhesiveness, when an antistatic layer is provided on the support of the image receiving sheet or the ink sheet.

Such the anti-static layer can be formed by coating and drying a coating liquid which contains the foregoing principal agent and a hardening agent in a suitable ratio, on at least one of the surface of the core material or support of the image receiving sheet and/or the ink sheet, or on a primer layer or a adhesive layer provided on the surface of the material of the support. The anti-static layer may be provided either on the surface of the core material or the support on which the ink layer or the image receiving layer is provided, or on the surface opposite to the surface on which the ink layer or the image receiving layer is provided. In the former case, the image receiving layer or the ink layer is provided on the antistatic layer. Moreover, another layer such as a heat resistive slippery layer or a back surface slippery layer may be provided on the anti-static layer. An ordinary method can be applied for providing such the layer.

61 4334 When the anti-static agent is added into the image receiving layer, the anti-static agent is soluble in an organic solvent. Examples of the organic solvent-soluble anti-static agent are described, for example, in JP-A-No. S64979.

The above-mentioned anti-static agent is preferably added into the image receiving layer in an amount of from 0.1 to 10 parts by weight per 100 parts by weight of the resin forming the image receiving layer. The antistatic effect become insufficient when the used amount is too low, and the dye acceptability the image receiving layer and the storage ability of formed image tend to degraded when the amount is excessive. it is preferable that the anti-static agent is distributed in the thickdirection of the image receiving layer so that not more than SO% by weight of the anti-static agent is contained within 1/5 of the thickness of the layer at the outer surface side. When the layer has such the structure, a good antistatic property can be stably maintained even when plural dye images are transferred on the same area of the image receiving sheet. It is preferable to form such the structure that the drying rate of the image receiving layer is set as slow as possible so that the antistatic agent having a molecular weight lower than that of the 62 4334 binder resin is distributed with a higher dense at the surface side of the image receiving layer.

The ink layer of the present invention may incorporate a low molecular substance having a melting point of 50 to 150 OC as a sensitizer. The sensitizer having the melting point of lower than 50 OC is not preferred because it tends to move to the surface of the ink layer and on the other hand, the sensitizer having the melting point of higher than 150 OC is not preferred because the sensitizing action decreases sharply.

Furthermore, the molecular weight of the sensitizer is preferably in the range of 100 to 1,500. The sensitizer having the molecular weight of less than 100 is not preferred because its melting point is generally lower than 50 OC. On the other hand, the sensitizer having the molecular weight of larger than 1,500 is also not preferred because the fusion sharpness is lost and the sensitizing action becomes insufficient.

Furthermore, the used amount of the above-mentioned sensitizer is preferably in the range of 1 to 100 parts by weight per 100 parts by weight of the binder employed to form the ink layer. The used amount of less than 1 part by weight is not preferred because no satisfactory sensitizing action is obtained. on the other hand, the used amount exceeding 63 4334 parts by weight is not preferred because the thermal resistance of the ink layer decreases.

As sensitizers such as mentioned above, known substance having a low molecular weight are available as far as those have a melting point of 50 to 150 OC. As those preferred, there are illustrated thermoplastic oligomers, for example, various kinds of oligomers such as polyurethane oligomer, polystyrene oligomer, polyester oligomer, polyacryl oligomer, polyethylene oligomer, polyvinyl chloride oligomer, polyvinyl acetate oligomer, ethylene/vinyl acetate copolymer oligomer, ethyleneacryl copolymer oligomer, polyoxyethylene oligomer, polyoxypropylene oligomer, polyoxyethylenepropylene oligomer, etc., fatty acids such as myristic acid, palmitic acid, margaric acid, stearic acid, arachic acid, montanic acid, etc., fatty acid amides such as caproic acid amide, caprylic acid amide, lauric acid amide, stearic acid amide, oleic acid amide, eicosanic acid amide, etc., fatty acid esters such as methyl behenate, pentadecyl palmitate, hexacosyl stearate, [1,4-phenylenebis(methylene)lbisdimethyl carbamate, etc., and aromatic compounds such as 1,4-dicyclohexylbenzene, benzoic acid, aminobenzophenone, dime tyl terephthal ate, fluoranthene, phenols, naphthalenes, phenoxys, various waxes, etc.

A conventional heating apparatus such as thermal head, a heat roller, a thermal press employing metal plate or heat- 64 4334 resist silicone rubber, hot stamping etc. are employed as the heating apparatus employed for the thermal transfer recording method according to the invention. The thermal head and heat roller are preferably employed in view of size of the apparatus and compactness.

An apparatus illustrated in Fig. 2 may be employed, for example, as the thermal transfer recording apparatus. In Fig. 2, numeral 10 denotes ink sheet supplying roll, I is an ink sheet, 11 is a taking roll to wind up the used sheet 1, 12 is a thermal head, 13 is a platen roller, and 14 is an image receiving sheet interposed between the thermal head 12 and platen roller 13.

To form a transfer image by employing the thermal transfer recording apparatus illustrated in Fig. 2, and an ink sheet, for example, as illustrated in Fig. 1, yellow dye containing area Yl of the ink sheet 1 and image receiving layer of the image receiving sheet are superposed, and the yellow dye is transferred to image receiving sheet according to the image data by heating with thermal head to form yellow dye image at first, next magenta dye is similarly transferred imagewise from the magenta dye containing area M1 on the yellow image, then cyan dye is similarly transferred from the cyan dye containing area imagewise on the transferred image, at last, necessary substances are transferred from the area 4334 containing no dye (a protective layer) to the whole area of the image whereby the image forming is completed.

Continuous record can be made on the long rolled image receiving material which is reeled out by setting each of monochrome ink sheet of yellow, magenta and cyan, and a protect sheet on thermal apparatus arranged in order.

EXAMPLES

The embodiments of the present invention are described below with reference to examples. However, the present invention is not limited to these examples. Further, "parts" in description is "parts by weight". 1. Preparation of Ink Sheet <Preparation of Ink Sheet 1>: Metal Source Treatment Layer Ink Sheet

Each of yellow (Y), magenta (M), and cyan (C) ink layers and a metal source containing ink layer, having the composition described below, were applied (at a thickness of 1 pm after drying) onto the reverse surface of the protective layer of polyethylene terephthalate film (K-203E-6F, manufactured by Diafoil Hoechst Co.) having said protective layer with a thickness of 6 pm, employing a gravure method.

An ink sheet is thus obtained in which each of Y, M, and C ink layers and the metal source containing layer were formed 66 4334 in such order (hereinafter referred to as face order) as shown in Fig. 1.

(Cyan Ink Layer Coating Composition) Post-chelate dye, Exemplified Compound (28) 3 parts Polyvinyl butyral (KY-24, manufactured by Denki Kagaku Kogyo Co.) 5.5 parts Urethane-modified silicone resin (Diaroma SP-210.5, manufactured by DAINICHISEIKA COLOR & CHEMICAL Mfg. Co., Ltd.) 1.5 parts Methyl ethyl ketone 10 parts Cyclohexanone 10 parts (Magenta Layer Coating Composition) Post-chelate dye, Exemplified Compound (25) 3 parts Polyvinyl butyral (KY-24, manufactured by Denki Kagaku Kogyo Co.) 5.5 parts Urethane-modified silicone resin (Daiaroma SP-2105, manufactured by DAINICHISEIKA COLOR & CHEMICAL Mfg. Co., Ltd..) 1.5 parts Methyl ethyl ketone 80 parts Cyclohexanone 10 parts 67 4334 (Yellow Layer Coating Composition) Post-chelate dye, Exemplified Compound (26) 3 parts Polyvinyl butyral (KY-24, manufactured by Denki Kagaku Kogyo Co.) 5.5 parts Urethane-modified silicone resin (Daiaroma SP-2105, manufactured by DAINICHISEIKA COLOR & CHEMICAL Mfg. Co., Ltd.) 1.5 parts Methyl ethyl ketone 80 parts Cyclohexanone 10 parts (Metal Source Containing Layer Coating Composition) Polyvinyl butyral (KY-24, manufactured by Denki Kagaku Kogyo Co., Ltd.) 9.5 parts Metal source (MS-1) 0.5 part Methyl ethyl ketone 80 parts Toluene 10 parts MS-1: Ni2+ IC7H15COC (COOCH3) =C (CH3) 0-13 <Preparation of Ink Sheet 2>: Ink Sheet with Protective Layer An ink sheet was obtained in such a manner that the protective layer described below was formed in the face order on each of Y, M, and C ink layers of Ink Sheet 1. <Protective Layer Coating Composition> 68 4334 Styrene acrylonitrile (Litac A100PC, manufactured by Mitsui Kagaku Co., Ltd.) 6 parts Polystyrene (Himer SBM73F, manufactured by -SANYO CHEMICL INDUSTRIES, LTD.) 2 parts Acrylic acid styrene (GP-301, manufactured by TOAGOSEI CO., LTD.

6 parts Aforementioned metal ion compound (MS-1) 0.75 part Methyl ethyl ketone MEK 59 parts Toluene 25 parts 2. Preparation of Image Receiving Sheet <Preparation of Support> As porous PET sheet A, a f irst layer, a second layer, and a third layer were simultaneously extruded at 300 OC, employing an extruder, and a sheet comprised of three layers was formed on a stainless steal belt, and then solidified by cooling. The resulting film was stretched three times in the conveying direction while being conveying by a roll heated at 115 'C. Subsequently, while holding both edges of the film employing clips, said film was stretched three times in the perpendicular direction to the conveying direction. Thereafter, the resulting film was thermally fixed at 200 'C, 69 4334 and cooled gradually to room temperature. Thus, a PET f ilm sheet having an 8 pm thick first layer, a 35 gm thick second layer, and an 8 pm thick third layer and having a specific gravity of 0.7 was prepared.

Composition of first layer and third layer PET Composition of second layer PET 90 parts PET-PTMG (prepared while adding PTMG so that during polymerization of PET, the weight ratio of PET to PTMG (polyteramethylene glycol having a molecular weight of 4,000) is 1: 1) 1 part Syndioctatic styrene (Zarekku S10, manufactured by Idemitsu Sekiyu Kagaku Co., Ltd.) 6 parts Both sides of PET sheet prepared as described above were subjected to corona discharge treatment. The resulting porous PET sheet A was adhered with a 150 pm thick wood free paper having a weight of 130 g/M2, employing polyethylene adhesive while passing those through a laminator at 140 'C, and PET-paper laminated sheet B was produced.

4334 A subbing layer forming coating composition having the composition described below was applied onto one surface of said Sheet B employing a wire bar coating method to f orm a 0.2 pm thick subbing layer, and the resulting coated layer was dried at 120 'C for one minute to form a support for the image receiving sheet.

(Subbing Forming Coating Composition) Nikasol A-08 (manufactured by Nihon Carbide Co.) 5.7 parts Pure water 94.0 parts <Preparation Image Receiving Sheet 1> The image receiving layer forming coating composition described below was applied to the support prepared as described above so as to obtain a dried layer thickness of 2.5 g/M2 employing a wire bar, and subsequently dried at 110 'C for 30 seconds to prepare Image Receiving Sheet 1.

(Image Receiving Layer Forming Coating Composition 1) Styrene acrylonitrile (Stylac 793, manufactured by Asahi Kasei Kogyo Co., Ltd.) 8.5 parts Aforementioned metal ion containing material (MS-1) 1.5 parts 71 4334 Post-chelate dye, Exemplif ied Compound (27) 0.005 parts Post-chelate dye, Exemplified Compound (28) 0.005 parts MEK (methyl ethyl ketone) 80 parts Butyl acetate 10 parts The resulting coating composition was applied and subsequently dried to obtain image Receiving Sheet 1. <Preparation of Image Receiving Sheet 2> Image Receiving Sheet was prepared by replacing Litac 783 in Image Receiving Layer Forming Coating Composition 1 of Image Receiving Sheet 1 with the compound described below.

Styrene acrylonitrile (Stylac 8707, manufactured by Asahi Kasei Kogyo Co., Ltd.) <Preparation of Image Receiving Sheets 3 and 4> The image receiving layer forming coating composition described below was applied onto the support which was employed to prepare Image Receiving Sheet 1 so as to obtain a dried layer thickness of 2.5 g/M2 employing a wire bar, and subsequently dried at 110 'C for 30 seconds. Further, onto the resulting coated layer, the releasable layer coating composition 1 or 2 was applied so as to obtain a dried layer thickness of 0.05 g/m2 employing a wire bar and similarly 72 4334 dried at 110 'C for 30 seconds to prepare Image Receiving Sheet 3 and 4. <Image Receiving Layer Forming CoatingComposition> Styrene acrylonitrile (Stylac 8707, Asahi Kasei Kogyo Co., Ltd.) 8.5 parts Aforementioned metal ion containing material (MS-1) 1.5 parts Post-chelate dye, Exemplified Compound (27) 0.005 part Post-chelate dye, Exemplified Compound (28) 0.005 part MEK 80 parts Butyl acetate 10 parts <Releasable Layer Coating Composition 1> Methylstyryl-modified silicone oil (Shin-Etsu Kagaku Co., Ltd., KF410) 0.5 part Methylcyclohexane 99.5 parts <Releasable Layer Coating Composition 2> Polyester -modi f i ed silicone oil (Shin-Etsu Kagaku Co., Ltd., X-24-8300) 0.5 part Methylcyclohexane 99.5 parts Example 1 (corresponding to items I through 3) 73 4334 The evaluation described below was carried out employing obtained Image Receiving Sheets 1 through 4 as well as Ink Sheet 1. Table 1 shows the results. (Evaluation) Each of Y, M, C, and K colors was printed onto each of thermal transfer image receiving materials consisting of the obtained ink sheet and image receiving sheet at a 255gradation value as well as the gradation value of every 20gradation, employing a sublimation transfer printer (CHCS545, manufactured by Shinko Denki Co., Ltd.), and subsequently, the entire image surface was subjected to postthermal treatment employing the same thermal head. -Printing Sensitivity The Y density at 255-gradatin value of each of print samples was measured and designated as printing density. -Image retention quality Each of print samples was left undisturbed in a xenon fade meter (70,000 lux) for 3 months at the constant ambient conditions of 60 'C and 80 percent. The remaining density ratio of a magenta color area having a density of 1.0 before and after the irradiation was measured. Image density was measured employing an X- rite 310. -Fusion Properties 74 4334 During printing, the fusion properties of each of ink sheets were visually evaluated. The K color part superimposed with Y, M, and C was evaluated as described below. A: no fusion was observed-up to Dmax (255- gradation value) B: fusion occurred at Dmax (between 240- and 255- gradation value) C: fusion occurred even at the halftone area (no more than 240-gradation value) Table 1

Image Binder MF (in Releasable Fusion Image Retention Printing Receiving g/10 Layer Properties Quality Sheet min.) of Ink Sheet 60 OC/80% Xenon Sensitivity 1 Stylac 783 9 none A 90 % 70 % 1.6 2 Stylac 8707 30 none B 90 % 85 % 1.9 3 Stylac 8707 30 Kf-410 A 90 % 85 % 1.85 4 Stylac 8707 30 X-24-8300 A 90 % 85 % 1.85 -3 Ln 0. w w P.

76 4334 MF: melt flow rate specified by JIS K 7210 As can clearly be seen from Table 1, it is found that when the image receiving sheets (items 1 through 3) of the present invention are employed, both of the image retention quality and printing sensitivity are excellent. Specifically, it is found that when the releasable layer is provided, the fusion with the ink sheet is minimized, and the best effects are exhibited. Example 2 (corresponding to items 4, 10 and 11) Obtained Image Receiving Sheets 2 through 4 as well as Ink Sheet 2 were subjected to evaluation of Example 1 (fusion properties and image retention quality), and the evaluation described below. Table 2 shows the results.

Each of Y, M, C, and K colors was printed onto the image receiving sheet employing obtained Ink Sheet 2 at a 255-gradation value as well as the gradation value of every 20-gradation, while employing a sublimation transfer printer (CHC-S545, manufactured by Shinko Denki Co., Ltd.), and subsequently, the entire image surface was subjected to protective layer transfer treatment, employing the same thermal head. -Protective Layer Properties The surface of an image part was kept rubbing for 10 seconds employing an eraser, and the ratio of remaining image 77 4334 density before and after erasing was measured (eraser resistance). A: remaining ratio was 100 percent. B: remaining ratio was 80 percent. C: remaining ratio was no more than 80 percent.

Further, a mending tape (manufactured by Sumitomo 3M Ltd.) was adhered onto the surface of the protective layer. When the adhered tape is peeled off, it was visually evaluated whether the protective layer itself is peeled off with the tape (adhesive properties). A: the surface layer was not peeled off. B: the surface layer was partially (10 percent of the total area) was peeled off. C: at least 10 percent of the image area was peeled off.

Table 2

Image Releasable Fusion Image Retention Protective Layer Properties Receiving Layer Properties Quality Sheet of Ink Sheet 60 OC/80 Xenon Eraser Adhesive percent Resistance Properties with Image Receiving Layer 2 none 90 % 85 % C A 3 KF-410 A 90 % 85 % A A 4 X-24-8300 A 90 % 85 % A C $h W W Al 79 4334 As can clearly be seen from Table 2, it is found that when the image receiving sheet (item 4) of the present invention is employed, the image retention quality are excellent; further, no fusion with the ink sheet occurs; and still further, the image retention quality due to the protective layer as well as the adhesive properties of the image receiving layer with the protective layer are improved. Example 3 (corresponding to items 5 through 9) <Preparation of Ink Sheet 11> An ink layer as well as a protective layer having the composition described below was applied onto a thickness 6 pm PET film having a heat resistant strip layer (having a thickness of 1 gm) on the reverse surface, . which had been subjected to primer treatment on its surface, and each of monochromatic color sheets as well as a protective sheet were prepared. Ink Layer 1 Composition (dried layer thickness of 1.1 pm) Y: Dye Y-1 described below 3.0 parts Polyvinyl butyral (Denka Butyral KY-24, manufactured by Denki Kagaku Kogyo Co., Ltd.) 5.5 parts 4334 Epoxy-modified acrylic resin (Rezeta GP-305, manufactured by TOAGOSEI CO., LTD.) 1. 0 part Urethane-modified silicone oil (Daiaroma SP-2105, manufactured by DAINICHISEIKA COLOR & CHEMICAL Mfg. Co., Ltd.) 0.5 part MEK 80 parts Toluene 10 parts M: Dye Y-1 in the aforementioned composition was replaced with M-1. C: Dye Y-1 in the aforementioned composition was replaced with C-1. Protective Layer 1 Composition (dried layer thickness of 2.5 P.M) Styrene acrylonitrile resin (Litac A100PC, manufactured by Mitsui Kagaku Co., Ltd. 6.0 parts Polystyrene resin (Himer SBM73F, manufactured by SANYO CHEMICL INDUSTRIES, LTD.

2.0 parts Acrylic acid styrene (GP-301, TOAGOSEI CO., LTD.) 6.0 parts metal ion containing compound (MS-2) 0.75 part MEK 59 parts 81 Toluene 25 parts Y-1 IC2H5)2 C or" CH3 CN F 0 XaN -N H 4 i HO 0 C4H!g(n) M-1 NH2 N -N(CA)2 0 OH C-1 H3COCH ZC2H5 _rN,,_ F C2H40 Ir CH3 H3C N N N(C2H5)2 MS-2 NF--(CSH12- F- CH-COOCH3)2 0 COCH3 Protective Layer 2 Composition (dried layer thickness of 2.5 PM) MS-2 was removed from the aforementioned Protective Layer Composition 1.

82 4334 Protective Layer 3 Composition (dried layer thickness of 2.5 MS-2 in the aforementioned Protective Layer Composition 1 was removed and 1.0 part of a UV absorber (Tinuvin-P, manufactured by Ciba-Geigy Co., Ltd. ) was added. Protective Layer 4 Composition (dried layer thickness of 2.5 Wn) MS-2 was removed from the aforementioned Protective Layer Composition 1, and 0.1 part of a light stabilizer (Tinuvin-144, manufactured by CibaGeigy Co., Ltd.) was added.

The Protective Layer 5 Composition described below was applied, and onto the resulting coated layer, the adhesive layer composition described below was applied employing a gravure method to prepare Protective Layer 5. Protective Layer 5 Composition (dried layer thickness of 2. 0 JIM) Styrene acrylonitrile resin (Litac A100PC, manufactured by Mitsui Kagaku Co., Ltd. 7.0 parts Polystyrene resin (Himer SBM73F, manufactured by SANYO CHEMICL INDUSTRIES, LTD.

3.0 parts 83 4334 MEK.55 parts Toluene 35 parts Protective Layer 5 Adhesive Layer Composition (dried layer thickness of 0.5 pm) Acrylic acid styrene (CP-301, manufactured by TOAGOSEI CO., Ltd.) 6.0 parts Polystyrene resin (Himer SBM73F, manufactured by SANYO CHEMICL INDUSTRIES, LTD.) 2.0 parts UV absorber (Tinuvin-P, manufactured by Ciba-Geigy Co., Ltd.) 2.0 parts MEK 55 parts Toluene 35 parts Protective Layer 6 Composition MS-2 was removed from Protective Layer 1 composition, and 1.0 part of a polymer UV absorber (UVA-635L, manufactured by BASF Co.) was added. <Preparation of Ink Sheet 12> Ink sheet 12 was prepared in the same manner by employing Composition 2 described below, which was obtained by varying the ink layer composition of Ink Sheet 11.

Ink Layer 2 Composition (dried layer thickness of 1.1 pm) 84 4334 Y: yellow disperse dye (Macrolex Yellow 6G, manufactured by Bayer Co.) 5.5 parts Polyvinyl butyral resin (S-lex BX-1, manufactured by Sekisui Kagaku Co., Ltd.) 4.5 parts MEK 40 parts Toluene 40 parts M: the dye in the aforementioned composition was replaced with a magenta disperse dye (Disperse Red 60, MS Red G, manufactured by Mitsui Toatsu Kagaku Co., Ltd.). C: the dye in the aforementioned composition was replaced with a cyan disperse dye (Solvent Blue 63, Kayaset Blue, manufactured by Nihon Kayaku Co., Ltd.) <Preparation of Image Receiving Sheet 11> A 150 pm thick wood-free paper having a weight of 130 g/M2 was laminated on one surface with a 50 pm thick white PET (Lumirror 50QE02, manufactured by Toray Co., Ltd.) which had been subjected to primer treatment on both surfaces, and on the other surface with a 110 pm thick transparent PET (Lumirror, manufactured by Toray Co., Ltd.) through a laminator at 140 'C, employing polyethylene as the adhesive, and thus Support 11 was prepared. The image receiving composition described below was applied onto the surface of the white PET of Support 11 so as to obtain a dried layer 4334 thickness of 2.5 pin, employing a wire bar, and subsequently dried at 110 C for 20 seconds to prepare an image receiving layer. The resulting coating was wound onto a vinyl chloride winding core with an outer diameter of 30 mm and a width of 140 mm so that the image receiving layer is faced up in the roll. Thus a wound thermal transfer image receiving sheet with a length of 24 m and a width of 110 mm was prepared.

Image Receiving Layer 1 Composition Styrene acrylonitrile resin (Stylac 8707 having an MF of 3.0 g/10 minutes), manufactured by Asahi Kasei Kogyo Co., Ltd.) 6.5 parts metal ion containing compound MS-2 2.5 parts Methylstyryl-modified silicone oil (KF410, manufactured by Shin-Etsu Kagaku Co., Ltd.) 1.0 part MEK 80 parts Butyl acetate 10 parts <Preparation of Image receiving Sheet 12> Both surfaces of a 150 pm thick wood-free paper with a weight of 130 g/m2 was dry-laminated with a 60 pm thick synthetic paper (Yupo FPG, manufactured by Oji Yuka Goseishi), which had been subjected to primer treatment 86 4334 employing a solution prepared by dissolving chlorinated polypropylene in a mixed solvent of toluene and MEK (with a weight ratio of 1/1), employing a urethane based adhesive. The interlayer composition described below was applied onto the resulting base material so as to obtain a dried layer thickness of 1 gm, and thus Support 12 was prepared. Image Receiving Layer 1 composition employed in Image Receiving Sheet 11 was applied to the surface of the side having the interlayer so as to obtain a dried layer thickness of 2.5 pm, and subsequently dried at 110 'C for 20 seconds to form an image receiving layer. The resulting coating was wound onto a vinyl chloride winding core with an outer diameter of 30 mm and a width of 140 mm so that the image receiving layer is faced up in the roll. Thus a wound thermal transfer image receiving sheet with a length of 24 m and a width of 110 mm was prepared.

Interlayer Composition Polyester resin (WR-905, manufactured by Nihon Gosei Kagaku Kogyo Co., Ltd.) 25 parts Water-soluble fluorescent whitening agent (Uvitex BAC, manufactured by Ciba-Geigy Co.) 1 part 87 4334 Titanium oxide (TCA-88, Tokemu Product Co.) 75 parts Water/propyl alcohol (1/1) 400 parts <Preparation of Image Receiving Sheet 13> In Image Receiving Sheet 12, the Image Receiving Layer 2 Composition described below was employed.

Image Receiving Layer 2 Composition Styrene acrylonitrile copolymer resin (Stylac 783 having an MF of 9 g/10 minutes), manufactured by Asahi Kasei Kogyo Co., Ltd.) 6.5 parts Metal ion containing compound MS-2 2.5 parts Methylstyryl-modified silicone oil (KF410, manuf actured by Shin-Etsu Kagaku Co., Ltd.) 1.0 part MEK 80 parts Butyl acetate 10 parts <Preparation of Image Receiving Sheet 15> In Image Receiving Sheet 12, the Image Receiving Layer 4 Composition was employed. Image Receiving Layer 4 Composition 88 4334 Acrylonitrile acrylic rubber-styrene copolymer (Vitax V6700 having an MF of 8 g/10 minutes, manufactured by Hitachi Kasei Kogyo Co., Ltd.) 6.5 parts Metal ion containing compound MS-2 2.5 parts Methylstyryl-modified silicone oil (KF410, manufactured by Shin-Etsu Kagaku Co., Ltd.) 1.0 part MEK 80 parts Butyl acetate 10 parts <Preparation of Image Receiving Sheet 16> In Image Receiving Sheet 12, the Imagg Receiving Layer Composition was employed.

Image Receiving Layer 5 Composition Styrene acrylonitrile (Stylac having an MF of 30 g/10 minutes, manufactured by Asahi Kasei Kogyo Co., Ltd.) 6.5 parts Metal ion containing compound MS-2 2.5 parts Amino-modified silicone oil (KF393, manufactured by Shin-Etsu Kagaku Co., Ltd.) 0.5 part 89 4334 Epoxy-modified silicone oil (X22-343, manufactured by Shin-Etsu Kagaku Co., Ltd.) 0.5 part MEK 80 parts Butyl acetate 10 parts <Preparation of Image Receiving Sheet 17> In Image Receiving Sheet 13, the Image Receiving Layer 6 Composition described below was employed.

Image Receiving Layer 6 Composition Styrene acrylonitrile copolymer resin (Stylac 8707 having an MF of 30 g/10 minutes), manufactured by Asahi Kasei Kogyo Co., Ltd.) 6.0 parts Metal ion containing compound MS-2 2.0 parts Methylstyryl--modified silicone oil (KF410, manufactured by Shin-Etsu Kagaku Co., Ltd.) 1.0 part Dioctyl phthalate 1.0 part MEK 80 parts Butyl acetate 10 parts <Preparation of Image Receiving Sheet 18> In Image Receiving Sheet 18, the Image Receiving Layer 7 Composition described below was employed.

4334 Image Receiving Layer 2 Composition Styrene acrylonitrile copolymer resin (Stylac 8707 having an MF of 30 g/10 minutes), manufactured by Asahi Kasei Kogyo Co., Ltd.) 5.0 parts Metal ion containing compound MS-2 2.0 parts Methylstyryl-modified silicone oil (KF410, manufactured by Shin-Etsu Kagaku Co., Ltd.) 1.0 part Dioctyl phthalate 2.0 parts MEK 80 parts Butyl acetate 10 parts <Preparation of Image Receiving Sheet 19> In Image Receiving Sheet 12, the metal ion compound was removed. <Preparation of Image Receiving Sheet 20> In Image Receiving Sheet 20, the Image Receiving Layer 9 Composition described below was employed. Image Receiving Layer 9 Composition 91 4334 Styrene acrylonitrile copolymer resin (Litac A200 having an MF of 15 g/10 minutes), manufactured by Mitsui Kagaku Co., Ltd.) 6.5 parts Metal ion containing compound MS-1 2.5 parts Methylstyryl-modified silicone oil (KF410, manufactured by Shin-Etsu Kagaku Co., Ltd.) 1.0 part Dioctyl phthalate 2.0 parts MEK 80 parts Butyl acetate 10 parts <Preparation of Image Receiving Sheet 21> In Image Receiving Sheet 21, the Image Receiving Layer Composition described below was employed.

Image Receiving Layer 10 Composition Styrene acrylonitrile copolymer resin (Stylac 767 having an MF of 12.5 g/10 minutes), manufactured by Asahi Kasei Kogyo Co., Ltd.) 6.5 parts Metal ion containing compound MS-2 2.5 parts 92 4334 Methylstyryl-modified silicone oil (KF410, manufactured by Shin-Etsu Kagaku Co., Ltd.) 1.0 part Dioctyl phthalate 2.0 parts MEK 80 parts Butyl acetate 10 parts <Preparation of Print samples> By employing obtained Ink Sheets 11 and 12, as well as Image Receiving Sheets 11 through 19, Y, M, C, and BK (black) patches were prepared employing a color printer of which schematic view is shown in Fig. 3.

Further, in Fig. 3, each roll of monochromatic yellow, magenta, cyan sheets, and a protective sheet was installed in a heating device successively arranged. Each roll was unwound from feeding roll 31; the supplied sheet was heated and printed at thermal head 34 according to image information; and was wound by winding roll 32. An image receiving material (sheet) was unwound from long roll 33 and provided for continuous printing. <Evaluation Methods> Printing Sensitivity Of obtained print sample, the yellow reflection density of the part (Dmax) printed employing 255-gradation value 93 4334 signal data was evaluated, based on the standard described below. A: Dmax was at least 2.2. B: Dmax was at least 2.0 and less than 2.2. C: Dmax was at least 1. 8 and less than 2. 0. D: Dmax was less than 1.8. Light Fastness of obtained print samples, each of parts, having a cyan refection density of 1.0, was left undisturbed in a xenon fade meter (70, 000 lux) for two weeks. Thereafter, a remaining density ratio was evaluated, based on the standard described below. A: at least 90 percent B: no less than 80 to less than 90 percent C: no less than 70 to less than 80 percent D: less than 70 percent Bleeding due to Heat and Moisture of obtained print samples, each of parts having a magenta reflection density was left undisturbed for three months at 60 'C and 80 percent. Bleeding at the edges was visually evaluated, based on the standard described below. A: no bleeding was observed. B: slight bleeding was observed with a magnifier.

94 4334 C: slight bleeding was observed without a magnifier, which caused problems on the market. D: marked bleeding was observed. Background Yellow Stain due to Heat

Of obtained print samples, each of white backgrounds was left undisturbed for two weeks at 85 'C and 60 percent.

Thereafter, the increase ratio of reflection density (under a blue filter) of the white background was evaluated, based on the standard described below. A: AD:5-- 0. 0 5

B: 0.05 < AD:< 0.1 C: 0.1 < AD Surface Contact Resistance (transparent vinyl film) Each image surface of obtained print samples was brought into contact with a vinyl chloride film (Arutoron) under a load of 20 g/CM2 and left undisturbed for two weeks at 40 'C and 80 percent. Thereafter, the reverse transfer of an image to said vinyl chloride film was visually evaluated, based on the standard described below. A: no reverse transfer was observed. B: slight reverse transfer was observed, but image degradation such as a decrease in density as well as uneven density was not observed.

4334 C: slight reverse transfer was observed and a decrease in density as well as uneven density was visually observed. D: reverse transfer to the vinyl chloride film was clearly observed and marked degradation of the image was also observed. Degradation of Image due to Contact between Image Surf aces The image surf ace of the print sample was brought into contact with the image surface of the same print sample under 2 a load of 20 g/cm, while the contact was carried out so that the images do not coincide with each other, and was left undisturbed for two weeks at 40 'C and 80 percent. Thereafter, degradation of both images was visually evaluated based on the standard descried below. A: in both images, background stain as well as transfer of images was not observed. B: in both images, slight background stain as well as slight transfer of images was observed. C: in both images, transfer of images was clearly observed. Transferability of Protective Layer

A mending tape (manufactured by Sumitomo 3M Ltd.) was adhered onto each image surface of obtained print samples, and was peeled off. During such test, peeling of the protective layer was visually evaluated, based on the standard described below.

96 4334 A: no peeling was observed.

B: partial peeling was observed (no more than 50% of the entire area for evaluation).

C: peeling readily occurred (at least 50% of the entire area for evaluation).

Table 3 shows the obtained results.

Table 3

Ink Sheet Image Receiving Sheet No. Ink Layer Protective No. Image Receiving MFR 0 f Region Layer Region Layer Resin Composition Composition Composition No.

No. No.

Example 1 11 1 1 11 1 30 Example 2 11 1 2 11 1 30 Example 3 11 1 3 11 1 30 ExamDle 4 11 1 4 11 1 30 Example 5 11 1 6 11 1 30 Example 6 11 1 1 16 5 30 Example 7 11 1 1 12 1 30 Example 8 12 2 1 12 1 30 Example 9 12 2 3 12 1 30 Comparative 1 11 1 1 13 2 9 Comparative 3 11 1 1 15 4 9 Comparative 4 11 1 1 19 8 30 Comparative 5 11 1 None 12 1 30 Comparative 7 11 1 None 16 5 30 Comparative 8 11 1 None 17 6 30 Comparative 9 11 1 None 19 8 30 Comparative 10 11 1 1 20 9 is Comparative 11 11 1 1 21 10 12.5 ko indicates that heating was carried out only with PET.

Table 3 (Cont.) Evaluation Results Printing Light Bleeding Yellow Vinyl Film Contact Protective Sensit- Fastness due to Stain Resistance Resistance Layer ivity Heat between Transfer Imaqes ability Example 1 A B A A A A A Example 2 A B A A A A A Example 3 A A A A A A A Example 4 A B A A A A A Example 5 A A A A A A A Example 6 B B B A A A A Example 7 B B A A A A A Example 8 B B B A A A A Example 9 B B B A A A A Comparative 1 C C B A A A C Comparative 3 C C C A A A C Comparative 4 C D C A A A A Comparative 5 B B A A D D - Comparative 7 B B B A D D - Comparative 8 B B B B D D - Comparative 9 C D C A D D - Comparative 10 C C B A A A B Comparative 11 C C B A A A B ko OD 4N. W W d:- 99 4334 As can clearly be seen from Table 3, when the protective layer is thermally transferred to the image receiving sheet according to the present invention, excellent images are obtained, and excellent retention quality as well as excellent durability is also obtained.

According to item 1 though 4, when image formation is carried out employing the post-chelate technique, it is found that the image retention quality are improved; further, no fusion with the ink sheet occurs; and the image durability due to the protective layer as well as the adhesive properties of the image receiving layer with the protective layer is improved.

* According to item 4, by employing the same post-chelate technique, markedly excellent effects are exhibited in which no fusion with the ink sheet occurs; neither discoloration as well as bleeding of images occurs during storage under severe conditions over an extended period of time; and sufficient image retention quality as well as light fastness are obtained; and further, the image density is enhanced.

According to the present invention described in items 5 through 9, when a thermal transfer image is formed, image retention quality is not degraded by providing a protective layer; even when acrylic resins, which exhibit excellent durability but insufficient dye transferability, are employed 4334 in an image receiving layer, neither decomposition of dyes, due to light, heat, moisture, and the like, nor retransfer of dyes due to physical contact of a print surface occurs; compatibility of the protective layer with the image receiving layer is enhanced even in the absence of an adhesive layer to enhance adhesion between the protective layer and the image receiving layer; and without adding an excessive amount of plasticizers to the image receiving layer, diffusion of dyes are improved and adhesion of the protective layer is also enhanced.

101 4335GB

Claims (11)

1. Claims; 1. A thermal transfer image receiving material in which an image

   receiving layer is provided which is faced with an ink sheet comprising thermally diffusible dyes, and is heated imagewise with response to record signals so as to be capable of receiving a dye of said ink sheet, a thermal transfer image receiving material wherein said image receiving layer comprises at least a metal ion containing compound and an acrylic resin which includes an acryl based copolymer comprising at least one type of a styrene or derivative thereof as a monomer unit, wherein the acrylic resin has a melt flow rate of at least 20g/10 ml specified in JIS K 7210.
2. 2. The thermal transfer image receiving material of claim 1 wherein a releasing layer containing a silicon compound is provided on the image receiving layer.
3. 3. The thermal transfer image receiving material of claim 2, wherein the silicon compound contains an alkyl group, an alkylene group or a styryl group in its molecular structure.

   102 433SGB
4. 4. A thermal transfer image receiving material of claim I wherein the acrylic resin has a melt flow rate of at least 2Sg/10 ml specified in JIS K 7210.
5. S. A thermal transfer recording material comprising three elements of 1) an ink sheet comprising a support having thereon an ink layer containing a thermally diffusible dye or a thermally diffusible dye precursor, 2) an image receiving material comprising a support having thereon an image receiving layer containing a resin having a melt flow rate of at least 20 g/10 minutes, and 3) a protective sheet having an image protective layer region prepared by applying onto a support a resin which can be thermally transferred onto the image surface of an thermal transfer image formed by transferring the dye described in 1) onto the image receiving material described in 2).
6. 6. The thermal transfer recording material of claim 5 wherein the resin includes an acryl based copolymer comprising, as a monomer unit, 1) at least one type of styrene or derivative thereof and 2) at least one type of acrylic monomer.

   103 4335GB
7. 7. The thermal transfer recording material of claim 5 or 6 wherein the protective layer comprises at least one type selected from UV absorbers, antioxidants, and light stabilizers.
8. 8. The thermal transfer recording material of claim 5, 6 or 7 wherein the ink layer comprises a chelatable dye as a thermal transfer dye precursor and said image receiving layer comprises a dye fixing material which is capable of reacting with said dye precursor.
9. 9. The thermal transfer recording material of claim 5, 6, 7, or 8 wherein the protective sheet comprises a dye fixing material which is capable of forming a dye upon reacting with a thermally diffusible dye precursor.
10. 10. The thermal transfer receiving material of claim 1 wherein the acryl based copolymer comprises, as a monomer unit, 1) at least one type of styrene or derivative thereof and 2) at least one type of acrylic monomer.
11. 11. The thermal transfer receiving of claim 10, wherein the acrylic monomer includes acrylonitril monomer.