FR2744063A1 - THERMAL TRANSFER PRINTING SHEET AND DOUBLE-SIDED THERMAL TRANSFER PRINTING METHOD - Google Patents

Abstract

The thermal transfer printing sheet comprises a substrate sheet (2); an area (12) provided for front-end printing, which comprises at least one sublimable dye layer (13) composed of sections of one or more colors (13Y, 13M, 13C); and a reverse transfer printing area comprising at least one hot meltable ink layer (17) composed of sections of one or more colors, the two areas being provided alternately on one side of the substrate sheet . An image is printed on the front of an image receiving material by the transfer printing area on the front and another image is printed on the back of this material using the area for printing. print on the back.

Description

Thermal transfer printing sheet and printing method by

  The present invention relates to a thermal transfer printing sheet that can be used to transfer images, letters, symbols or the like on both sides of an image receiving material by a method of thermal transfer printing, and to a double-sided transfer printing process using

this leaf.

  Heretofore, a thermal transfer printing method has been used to form halftone images or letters, symbols, or the like on a subject receiving the images. The heat sensitive sublimation transfer printing method, or the hot melt transfer printing method, is widely used as a printing method by

Thermal transfer.

  The heat sensitive sublimation transfer printing method is as follows: a thermal transfer printing sheet comprising a substrate sheet and a sublimable dye layer provided thereon is superimposed on an image receiving material. sheet, containing a binder resin and, as a colorant, a sublimable dye which is dissolved or dispersed in the binder resin, and applying energy to the thermal transfer printing sheet by means of a heating device such as a thermal head, in accordance with the image information, so as to transfer the dye contained in the sublimable dye layer of the thermal transfer printing sheet to the image-receiving material, thereby producing a picture on the

matter of receiving the image.

  The hot melt transfer printing method is as follows: a thermal transfer sheet comprising a substrate sheet and a heat fusible ink layer provided thereon is superimposed on an image receiving material and containing a coloring agent such as a pigment, and a vehicle such as a wax, and applying energy to the thermal transfer printing sheet by means of a heating device such as a thermal head, conforming with image information, thereby transferring the softened hot meltable ink layer to the image receiving material, producing

  thus an image on the image receiving material.

  The heat-sensitive sublimation transfer printing method described above is advantageous in that it can produce an excellent halftone image because the amount of dye to be transferred to the image receiving material can be controlled at each point by changing the amount of heat applied to the thermal transfer printing sheet. However, line images such as letters or symbols produced by this method are of poor clarity, so that this printing method is not suitable for recording OCR letters, bar codes or the like. which are intended to be read optically. The hot melt transfer printing method is advantageous in that it can easily produce line images such as letters or symbols. However, it is difficult to produce by this printing process a halftone image such as

  than a photograph of a person's face.

  In order to solve the above-mentioned problems in thermal transfer printing processes, a thermal transfer printing sheet of a complex type, comprising a sublimable dye layer, is used for conductive transfer printing. a layer of hot-meltable ink which are provided alternately on one side of a continuous substrate sheet. The thermal transfer printing sheet 71 shown in Fig. 10 is an example of such a thermal transfer printing sheet. This thermal transfer printing sheet comprises a sublimable dye layer 72 composed of sections of three colors (72Y, 72M, 72C), yellow (Y), magenta (M) and cyan (C) and a fusible ink layer. heat pump composed of a black ink layer 73 (BK) and a protective layer 74 (OP). In this thermal transfer printing sheet, the sublimable dye layer and the hot meltable ink layer are provided in sequence on one side of the substrate sheet in the YMC-BK-OP order, and this YMC unit -BK-OP is

planned repeatedly.

  The thermal transfer printing sheet

  The above is used, for example, as follows: after a halftone image has been formed using sublimable dye layer 72 (72Y, 72M, 72C) and letters, etc. are formed using the black ink layer 73 (BK) at the location of an image receiving material, the protective layer 74 (OP) is transferred to the entire surface of the image and letters, etc. which have been formed (the first Y-M-C-BK-OP repeating unit is used for these phases); the material of reception of the image is then returned and letters, etc. are formed using the black ink layer 73 (BK) on the back of the image receiving material (the second

  repetitive unit Y-M-C-BK-OP is used in this phase).

  In this way, in the second repetitive unit Y-M-C-BK-

  OP, only the ink layer 73 (BK) is used and the sublimable dye layer 72 ((72Y, 72M, 72C)) and the protective layer 74 (OP) are not used at all. The second repetitive unit in which only the black ink layer 73 (BK) is used alone can no longer be used to form an image on a new image-receiving material, so that it is necessary to use for this purpose the third and fourth repetitive units. This means that the sublimable dye layer (72Y, 72M, 72C) and the protective layer 74 (OP) are left unused in each of the other Y-M-C-BK-OP repeat units provided on this thermal transfer printing sheet. This thermal transfer printing sheet is therefore of poor performance in double-sided transfer printing and

  it is difficult to reduce the cost of use.

  The invention was made in the light of the circumstances mentioned above. An object of the invention is therefore to provide a thermal transfer printing sheet which can be used to efficiently transfer images, letters, symbols or the like on both sides of an image receiving material by a method thermal transfer printing, and to create a process

  double-sided transfer printing using this sheet.

  This object of the invention can be achieved by a thermal transfer printing sheet for thermally transferring images on both sides of an image receiving material, comprising a substrate sheet; an area provided for spot transfer printing comprising at least one sublimable dye layer composed of sections of one or more colors, and a region for reverse transfer printing comprising at least one layer of fusible ink at composed of sections of one or more colors, both zones being provided

  alternately on a first face of the substrate sheet.

  On the other hand, in the thermal transfer printing sheet according to the invention, the area provided for spot transfer printing comprises the sublimable dye layer described above and a transferable protective laminate, and the area provided for transfer printing on upside down includes the fusible ink layer

  described above and a transferable protective laminate.

  On the other hand, in the thermal transfer printing sheet according to the invention, the area provided for spot transfer printing comprises the sublimable dye layer described above, a hot meltable ink layer and a transferable protective laminate, and the reverse transfer printing zone comprises the hot meltable ink layer described above and a transferable protective laminate. Furthermore, in the thermal transfer printing sheet according to the invention, the sublimable dye layer described above is composed of sections of three colors, yellow, magenta and cyan, the hot meltable ink layer described above. is a black hot meltable ink layer and the transferable protective laminate is formed by laminating a protective layer and an adhesive layer on the substrate sheet, in that order, the protective layer comprising, as a main constituent, a mixture of an acrylic resin, a wax, a vinyl chloride-vinyl acetate copolymer, and a polyester resin or comprising, as a main constituent, an ionized radiation-cured resin, or comprising as a main constituent, a mixture of polymethylmethacrylate and a wax, or comprising, as main constituents, a water-soluble resin and

  particles insoluble in a solvent.

  On the other hand, in the thermal transfer printing sheet according to the invention, the transferable protective laminate described above is formed by laminating a protective layer, an ultraviolet absorbing layer and an adhesive layer on the substrate sheet, in this order, the ultraviolet absorber layer, comprising an ultraviolet absorbing polymer; the transferable protective laminate is formed by laminating a protective layer and a layer of adhesive on the substrate sheet, in this order, the adhesive layer comprising, as a main constituent, a vinyl chloride-vinyl acetate copolymer resin and / or a polymer

ultraviolet absorber.

  A double-sided transfer printing method according to the invention consists in superimposing the thermal transfer printing sheet on the surface of an image receiving material, in carrying out the transfer printing using the intended area. for in-place printing of the thermal transfer printing sheet, superimposing the thermal transfer printing sheet on the reverse of the image receiving material and executing the transfer printing using the area for transfer printing on the back of the sheet

  thermal transfer printing.

  Furthermore, a double-sided transfer printing method according to the invention consists of superimposing the thermal transfer printing sheet described above on the back side of an image receiving material, to execute the printing by transferring using the area for back transfer printing of the thermal transfer printing sheet, superimposing the thermal transfer printing sheet on the surface of the image receiving material, and conducting the printing by transfer using the area for transfer printing on the sheet

  thermal transfer printing.

  Furthermore, a double-sided transfer printing method according to the invention consists in superimposing, on the surface of an image-receiving material, a first thermal transfer printing sheet comprising a substrate sheet, a a sublimable dye layer composed of sections of one or more colors, and a layer of hot meltable ink composed of sections of one or more colors, the sublimable dye layer and the hot meltable ink layer being alternatively provided on one side of the substrate sheet, the area of the section of each color of the hot-meltable ink layer being twice as large as that of the section of each color of the sublimable dye layer; performing the transfer printing using the entire area of each section of the sublimable dye layer and half the area of each section of the hot-melt ink layer; superimposing on the surface of the image-receiving material a second thermal transfer printing sheet comprising a substrate sheet, and a transferable protective laminate provided on its surface; transferring the transferable protective laminate to the surface of the image receiving material; superimposing the first printing sheet by thermal transfer on the back of the image receiving material; and perform the transfer printing using the remaining half of each section of the hot-melt ink layer of the

  first printing sheet by transfer.

  Furthermore, a double-sided transfer printing method according to the invention consists in superimposing, on the surface of an image-receiving material, a first thermal transfer printing sheet comprising a substrate sheet, a sublimable dye layer composed of sections of one or more colors, a hot-meltable ink layer composed of sections of one or more colors, and a transferable protective laminate, the sublimable dye layer, the dye layer; hot-meltable ink and the transferable protective laminate being provided in sequence on a surface of the substrate sheet; performing the transfer printing using the sublimable dye layer, the hot melt ink layer and the transferable protective laminate; superimposing, on the reverse side of the image receiving material, a second thermal transfer printing sheet comprising a substrate sheet and a hot meltable ink layer composed of sections of one or more colors, provided on the substrate sheet; and perform the transfer printing using the hot-melt ink layer on the second printing sheet by

Thermal transfer.

  In the drawings, Fig. 1 is a plan view showing an example of the thermal transfer printing sheet according to the invention; Fig. 2 is a plan view showing another example of the thermal transfer printing sheet according to the invention; Fig. 3 is a plan view showing yet another example of the thermal transfer printing sheet according to the invention; Fig. 4 is a plan view showing yet another example of the thermal transfer printing sheet according to the invention; Fig. 5 is a schematic sectional view showing the structure of the thermal transfer printing sheet shown in Fig. 1; Fig. 6 is a schematic sectional view showing the structure of the thermal transfer printing sheet shown in Fig. 2; Fig. 7 is a schematic sectional view showing the structure of the thermal transfer printing sheet shown in Fig. 3; Figs. 8 (A) and 8 (B) are plan views showing a pair of thermal transfer printing sheets for use in the double-sided transfer printing method according to the invention; Figs. 9 (A) and 9 (B) are plan views showing another pair of thermal transfer printing sheet for use in the double-sided transfer printing method according to the invention; and Fig. 10 is a plan view showing a thermal transfer printing sheet for use in the conventional dual transfer printing method.

face.

  The invention will now be described in detail below

attached drawings.

  <Thermal transfer printing sheet according to the invention> Fig. 1 is a plan view showing an example of the thermal transfer printing sheet according to the invention. As shown in this figure, the thermal transfer printing sheet 11 has a region transfer printing area 12 and a reverse transfer printing area 16, which are provided in

  alternation on one side of a substrate sheet.

  Area 12 for spot transfer printing is constituted by a sublimable dye layer 13 composed of sections (13Y, 13M, 13C) of three colors yellow, magenta and cyan, and a transferable protective laminate 14. Area 16 for reverse transfer printing is

  formed by a heat fusible ink layer 17.

  Fig. 2 is a plan view showing another example of the thermal transfer printing sheet according to the invention. As shown in this figure, the thermal transfer printing sheet 21 comprises a zone 22 for transfer printing on location and a zone 26 for reverse transfer printing, which are provided

  alternately on a surface of a substrate sheet.

  Area 22 for spot transfer printing is constituted by a layer of sublimable dye 23 composed of sections (23Y, 23M, 23C) of three colors yellow, magenta and cyan, and a transferable protective laminate 24. The area 26 for printing by transfer on the back is constituted by a layer of hot meltable ink 27 and by

  a transferable protective laminate 28.

  This thermal transfer printing sheet 21 differs from the thermal transfer printing sheet 11 in that it also carries the transferable protective laminate 28 on the transfer printing area 26

on back.

  Fig. 3 is a plan view showing yet another example of the thermal transfer printing sheet according to the invention. As shown in this figure, the thermal transfer printing sheet 31 includes an area 32 for transfer printing on location and a zone 36 for reverse transfer printing, which are

  provided alternately on one side of the substrate sheet.

  Area 32 for spot transfer printing consists of a sublimable dye layer composed of sections (33Y, 33M, 33C) of three colors, yellow, magenta and cyan, by a hot meltable ink layer 34, and by 35. The zone 36 for reverse transfer printing is constituted by a

fusible ink layer 37.

  Fig. 4 is a plan view showing yet another example of the thermal transfer printing sheet according to the invention. As shown in this figure, the thermal transfer printing sheet 41 has a region transfer printing area 42 and a reverse transfer printing area 46 which are provided

  alternately on one side of the substrate sheet.

  Area 42 for spot transfer printing is constituted by a sublimable dye layer 43 composed of sections (43Y, 43M, 43C) of three colors yellow, magenta and cyan, a layer of hot meltable ink 44 and a transferable protective laminate 45. The zone 46 for reverse transfer printing consists of a hot-melt ink layer 47 and a laminate

transferable protector 48.

  This thermal transfer printing sheet 41 differs from the thermal transfer printing sheet 31 in that it also carries the transferable protective laminate 48 on the transfer printing area 36

on back.

  The structure of each of the thermal transfer printing sheets will now be described.

  the invention which have been described above.

  Fig. 5 is a schematic sectional view showing the structure of the thermal transfer printing sheet 11 shown in Fig. 1. As shown in this figure, the thermal transfer printing sheet 11 has an area 12 for transfer printing on location and a zone 16 for reverse transfer printing, which are provided alternately on one side of a substrate sheet 2. In addition, a reinforcing layer

  3 is provided on the other side of the substrate sheet 2.

  The substrate sheet 2 of the thermal transfer printing sheet 11 may be any suitable substrate sheet for a conventional thermal transfer printing sheet. Preferred examples of the substrate sheet include, in particular, thin papers such as crystal paper, capacitor paper, wax paper, and polyester films having a high heat resistance, such as polyethylene terephthalate, ethylene polynaphthalate, butylene polyterephthalate, phenylene polysulfide, polyether ketone, polyether sulfone, oriented or unoriented films of plastics such as polypropylene, polycarbonate, cellulose acetate, polyethylene derivatives , polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polymethylpentene and ionomers, as well as laminates of these materials. The thickness of the substrate sheet 2 may be suitably selected depending on the material used so that the substrate sheet may exhibit appropriate properties of strength, heat resistance and the like. In general, the substrate sheet 2 is preferably used for a sheet of

  thickness of about 1 to 100 micrometers.

  Sublimable dye layer 13 (13Y, 13M, 13C) contained in area 12 for spot-on printing of thermal transfer printing sheet 11

  comprises a sublimable dye bound by a binder resin.

  There is no particular limitation on the sublimable dye and any sublimable dye used for a conventional thermal transfer printing sheet for the heat sensitive sublimation transfer printing process can be used. Specific examples of the sublimable dye include Phorone Brilliant Yellow S-6GL, PTY-52 and Macrolex Yellow S-6G, as yellow dyes, MS Red, Macrolex Red Violet R, Ceres Red 7B, Samaron Red HBSL, and SK Rubine SGL as red dyes and Kayaset Blue 714, Waxoline Blue AP-FW, Phorone Brilliant Blue SR,

  MS Blue 100 and Daito Blue No. 1 as blue dyes.

  There is no particular limitation on the binder resin that will be used in the sublimable dye layer 13 and any binder resin used for a thermal transfer printing sheet for the printing process can be used. heat sensitive sublimation transfer. Specific examples of the binder resin include cellulosic resins such as ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate and cellulose acetate butyrate; and vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone and polyacrylamide, among these substances, polyvinyl acetal and polyvinyl butyral are particularly preferred from the point of view of resistance to heat and transfer of dyes by heating. If necessary, the sublimable dye layer 13 may contain various known additives, in addition to the dye and the binder resin

described above.

  The sublimable dye layer 13 may be formed by depositing an ink which is prepared by dissolving the dye and binder resin described above, as well as other additives contained in a suitable solvent, on the surface of the substrate sheet, by known means such as the etching process, and drying the deposited ink. The ink is deposited on the substrate sheet in such an amount that the sublimable dye layer 13 has a thickness of about 0.2 to 5 micrometers, preferably about 0.4 to 2 microns, and that contains approximately 5 to 90% by weight, preferably

  10 to 70% by weight of the sublimable dye.

  The transferable protective laminate 14 contained in the area 12 for spot transfer printing of the thermal transfer printing sheet 12 is formed by laminating a protective layer 14a and a layer

  adhesive 14b on the substrate sheet, in that order.

  The protective layer 14a, which is a component of the transferable protective laminate 14, comprises, as a main constituent, a mixture of an acrylic resin, a wax, a vinyl chloride-acetate copolymer,

vinyl and a polyester resin.

  The acrylic resin is of excellent transparency and can produce a relatively strong film. It can therefore give the protective layer 14a hardness, durability, such as scratch resistance, and chemical resistance. In addition, the transferable protective laminate can cut cleanly when it is thermally transferred to an image-receiving material if an acrylic resin is incorporated in the protective layer. A wax is incorporated into the protective layer 14a to impart slip properties. Examples of the wax that can be used include microcrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsh wax, and a variety of low molecular weight polyethylenes, Japanese wax, beeswax , spermaceti, insect wax, wool wax, shellac wax, candellia wax, petrolatum, partially modified waxes, fatty esters and fatty amides. It is preferable to use the wax described above in an amount of 1 to 20 parts by weight per 100 parts by weight of the acrylic resin used. When the wax is used in an amount of less than 1 part by weight per parts by weight of the acrylic resin, the resulting protective layer 14a may not have a sufficiently high scratch resistance. On the other hand, when the wax is used in an amount of more than 20 parts by weight, the resulting protective layer 14a is

  insufficient in sustainability and transparency.

  The vinyl chloride-vinyl acetate copolymer which is used as a constituent of the protective layer 14a, together with the acrylic resin and the wax described above, can provide flexibility to the protective layer 14a. The polyester resin which is used as a constituent of the protective layer 14a serves to control the release properties of the protective layer at the time of thermal transfer. He is

  it is preferable to use the vinyl chloride copolymer

  vinyl acetate in an amount of about 10 to 80 parts by weight per 100 parts by weight of the acrylic resin. It is preferable to use the polyester resin in an amount of about 0.1 to 5 parts by weight per 100 parts by weight

acrylic resin.

  It is also possible to incorporate in the protective layer 14 a substantially transparent inorganic or organic fine particles. When such fine particles are incorporated in the protective layer, the transferable protective laminate is cut more cleanly when heat transferred to an image receiving material, and the scratch resistance and other similar properties of the protective layer 14a. are also improved. In addition, the surface gloss of the protective layer 14a is reduced, so that the protective layer will have a matte surface. Examples of the fine particles that can be used include those that have relatively high transparency, such as silica, Teflon powder, and nylon powder. It is preferable to use the fine particles in an amount of 1 to 30% by weight of the acrylic resin. When the fine particles are used in an amount of more than 30% by weight of the acrylic resin, the resulting protective layer 14a has less transparency and

sustainability.

  On the other hand, when additives such as an ultraviolet absorber, an antioxidant and a fluorescent brightener are incorporated in the protective layer 14a, the image is transferred to an image-receiving material covered with the layer. protector 14a has better properties of gloss, light fastness,

  weather resistance, whiteness and the like.

  The adhesive layer 14b, which is a component of the transferable protective laminate 14, serves to increase the adhesion between the protective layer 14a and an image receiving material. The adhesive layer 14b may be formed by depositing on the protective layer 14a a solution of a resin which may exhibit high tack when thermally fused, such as acrylic resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, an acryl-vinyl-vinyl acetate terpolymer, a polyester resin or a polyamide resin, and drying the deposited resin solution. In the case where a material of the card type whose surface is made of a polyvinyl chloride resin is used as the image-receiving material, a vinyl chloride-vinyl acetate copolymer, a terpolymer can be used. acryl-vinyl-vinyl acetate chloride, an acrylic resin or a polyamide resin to provide a heat-sensitive adhesive that is highly adherent to the polyvinyl chloride resin and can be cut clean when heat-transferred to the material of reception of the image. The thickness of the adhesive layer 14b is about 0.5 to 10 microns. On the other hand, when additives such as the ultraviolet absorber, an antioxidant and a fluorescent brightener are incorporated in the adhesive layer 14b, an image transferred to an image receiving material, coated with the adhesive layer 14b, has improved properties of gloss, lightfastness, resistance

  weathering, whiteness and the like.

  The hot meltable ink layer 17 contained in the back transfer printing area 16 of the thermal transfer printing sheet 11 is formed by laminating an OP 17a release layer and a coloring ink layer 17b on the substrate sheet 2, in that order. The release layer OP 17a, which is a component of the hot meltable ink layer 17, comprises, as a main component, a mixture of an acrylic resin, a wax, a vinyl chloride copolymer, vinyl acetate, and a polyester resin, as the layer

protector 14a described above.

  The nonstick OP layer 17a may be formed by depositing a suitable composition on the substrate sheet 2 by known means, such as hot melt, hot lacquer, etching, reverse etching or

  roll coating and drying the deposited composition.

  The thickness of this anti-adhesive OP layer 17a is preferably about 0.1 to 5 microns. To matt the surface of the non-stick OP layer 17a, fine particles can be added to the non-stick OP layer 17a which can be incorporated in the protective layer 14a.

described above.

  The coloring ink layer 17b, which is a constituent of the hot meltable ink layer 17, comprises an agent

  dye, a vehicle and, if necessary, different additives.

  Of the organic or inorganic pigments or dyes, those which are preferable for constituting the coloring agent are those which have good properties of recording materials, for example those which can give sufficiently high color densities and which do not fade even when exposed to light or heat. The coloring agent is preferably carbon black or a red, blue or yellow pigment with which letters, symbols, or the like having high densities can be printed clearly on an image receiving material. To improve adhesion to an image receiving material, and to impart scratch resistance to an image transferred to image-receiving material, it is preferable to incorporate as a vehicle into the image-receiving layer. dye 17b one of the following resinous binders, such that the amount of the coloring agent is 20 to 80% by weight of the vehicle: (1) acrylic resin, (2) acrylic resin + chlorinated rubber

  (3) acrylic resin + chlorinated rubber copolymer

  vinyl acetate, (4) acrylic resin + cellulosic resin, and (5) vinyl chloride-acetate copolymer resin

vinyl.

  Moreover, it is possible to use a wax or the like in

  replacement or in addition to the resinous binder described above.

  above. Typical examples of wax include wax

  micro-crystalline, carnauba wax, paraffin wax.

  Apart from these waxes, mention may be made of various waxes such as Fischer-Tropsh wax, and a variety of low molecular weight polyethylenes, Japanese wax, beeswax, spermaceti, insect wax, wool wax, shellac wax, candellia wax, petroleum jelly, partially modified waxes, fatty esters and

fatty amides.

  This heat fusible type dye ink layer 17b can be formed by depositing a suitable ink on the surface of the nonstick OP layer 17a by known means such as the hot-melt, hot-lacquer, etching, reverse etching or roll coating, and drying the deposited ink. The thickness of the dye ink layer 17b is preferably about 0.2

at 10 micrometers.

  The reinforcing layer 3 provided on the other surface of the substrate sheet 2 prevents thermal fusion between a heating device such as a thermal head and the substrate sheet 2, so that the thermal transfer printing sheet is transported uniformly when thermal transfer printing is performed. Examples of the resin that can be used to form this reinforcing layer 3 include cellulosic resins such as ethyl cellulose, hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, acetobutyrate of cellulose and nitrocellulose, vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, acrylic resins such as polymethyl methacrylate, polyacrylate of ethyl, polyacrylamide and acrylonitrile-styrene copolymers, as well as natural or synthetic resins such as polyamide resins, polyvinyltoluene resins, coumarin and indene resins, polyester resins, polyurethane resins and silicone-modified urethanes or fluorine. These resins can be used, either alone or in combination. To provide greater heat resistance to the reinforcing layer 3, it is preferable to choose a resin having a reactive hydroxy group from the resins listed above and to use as a crosslinking agent a polyisocyanate or the like in conjunction with

  the resin to obtain a crosslinked resin layer.

  On the other hand, to make the thermal transfer printing sheet capable of sliding more evenly over a thermal head, it is possible to impart to the reinforcing layer 3 heat-resistant slip properties by adding a non-sticking agent thereto. or a solid or liquid lubricant. Examples for the release agent or lubricant include various waxes such as polyethylene wax and paraffin wax, higher aliphatic alcohols, organopolysiloxane, anionic surfactants, cationic surfactants, ampholytic surfactants, nonionic surfactants, fluorine-containing surfactants, organic carboxylic acids and derivatives thereof, fluorine resins, silicone resins and fine particles of an inorganic compound such as talc and silica. The amount of release agent or lubricant that can be incorporated into the backing layer 3 is 3 to 50% by weight, preferably about 10 to 30% by weight.

% in weight.

  The thickness of the reinforcing layer 3 is about 0.1 to 10 micrometers, preferably about 0.5 to 5 micrometers. It will be appreciated that an adhesion promoting layer may be provided on the surface of the substrate sheet 2 in order to improve the good adhesion of the substrate sheet 2 to the sublimable dye layer 13, to the coating layer. hot fusible ink 17 and the transferable protective laminate 14. Any layer may be used for this adhesion promoting layer provided that it can increase adhesion between the substrate sheet 2 and the transferable protective laminate 14. The adhesion promoting layer may be formed by depositing on the surface of the substrate a solution of a polyurethane resin, polyester resin, acrylic polyol resin or vinyl chloride-vinyl acetate copolymer, or a mixture of these resins, and drying the deposited solution. Moreover, a reactive hardening agent such as a polyisocyanate can be added, if necessary, and an agent can also be added.

coupling, titanate or silane.

  Fig. 6 is a schematic sectional view showing the structure of the thermal transfer printing sheet 21 shown in Fig. 2. As shown in this figure, the thermal transfer printing sheet 21 has a zone 22 for printing by transfer on location and a zone 26 for transfer printing on back, which are provided alternately on the same side of the substrate sheet 2. In addition, a reinforcing layer 3 is provided on the other side of the substrate sheet 2. The substrate sheet 2 and the reinforcing layer 3 are the same as those of the thermal transfer printing sheet 11 described above. We will therefore fail to explain them. The zone 22 for in-place printing of the thermal transfer printing sheet 21 is constituted by a sublimable dye layer 23 (23Y, 23M, 23C) and a transferable protective laminate 24. The sublimable dye layer 23 can be formed in the same way as in the formation of the sublimable dye layer 13 of the thermal transfer printing sheet 11 described above, so that an explanation for this layer will be omitted here. The transferable protective laminate 24 contained in the area 22 for transfer printing is formed by laminating a protective layer 24a. a primer layer 24b, an ultraviolet absorbing layer 24c and an adhesive layer 24d on the sheet

of substrate 2, in that order.

  The protective layer 24a, which is a component of the transferable protective laminate 24, comprises, as a main component, an ionized radiation-cured resin. The thickness of the layer

  Protector 24a is preferably from about 1 to 10 micrometers.

  The ionizing radiation cured resin, which is a constituent of the protective layer 24a, is obtained by crosslinking and curing a polymer or oligomer containing in its structure a radically polymerizable double bond by application of ionizing radiation. Alternatively, the ionizing radiation cured resin can be obtained by adding a photopolymerization initiator to the aforementioned polymer or oligomer and polymerizing and crosslinking the mixture by applying an electron beam or ultraviolet rays. There is no particular limitation for the ionizing radiation hardened resin and any ionizing radiation hardening resin can be used.

known in the classical technique.

  Examples of the above-mentioned radically polymerizable monomer include acrylate, methacrylate, acrylamide, methacrylamide, allylic compounds, vinyl ethers, vinyl esters, heterocyclic vinyl compounds, N-vinyl compounds, styrene, acrylic acid, methacrylic acid. crotonic acid and itaconic acid. Examples of the multifunctional monomer include the following: diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate,

  dipentaerythritol hexa (meth) acrylate, tris (beta)

  (Meth) acryloyl-oxyethyl) isocyanurate. In the case where the cured resin is obtained by application of ultraviolet rays, it is possible to add, as sensitizer, a compound which can dissociate a radical when ultraviolet rays are applied thereto, for example a benzo ether such as the following: benzoquinone, benzoin or benzoin methyl ether, a halogenated acetophenone or a diacetyl compound in an amount of about 1 to 20% by weight of the monomer radically

polymerizable described above.

  To obtain better flexibility and adhesiveness properties, a cellulosic resin such as ethyl cellulose, a polyester resin, a polyurethane resin, rosin ester resin, a rubbery resin such as

  cyclized rubber or an acrylic resin.

  These resins are certainly of excellent transparency, but they tend to form relatively strong films. There can thus be a case in which the protective layer formed using one of these resins can not be cut cleanly when transferred to an image receiving material in the heat transfer process which will be described later. . For this reason, it is preferable to add a relatively large amount of fine particles having high transparency to the ionizing radiation curable resin. Examples of such fine particles include inorganic fine particles such as silica, alumina, calcium carbonate, talc and clay, and inorganic fillers such as acrylic, polyester, melamine, epoxy resins and the like. polyethylene, which have particle diameters

from about 0.01 to 50 microns.

  In the case where fine particles of silica or alumina are used for the fine particles, it is possible to use silica or alumina whose surfaces of the particles have been treated with a silane coupling agent or analogous to improve compatibility with the ionizing radiation curable resin. Examples of the agent

  Coupling silane include the following: range-methacryl-

  oxypropyltrimethoxysilane, gamma-methacryloxypropylmethyl-

  dimethoxysilane, gamma-methacryloxypropyldimethyloxysilane, gamma-meth-

  acryloxypropyltriethoxysilane, gamma-methacryloxypropyldimethyloxy-

  silane, gamma-acryloxypropyltrimethoxysilane, gamma-acryloxypropyl-

  dimethylmethoxysilane, gamma-acryloxypropyltriethoxysilane, gamma-

  acryloxypropylméthyldiéthoxysilane, garmmna-acryloxypropyldiméthyléthoxy-

silane and vinylethoxysilane.

  The treatment capacity of the silane coupling agent is preferably such that the minimum coating area of the silane coupling agent is from 10 to 100% of the specific surface area of the silica or alumina. It is preferred that 5 to 50 parts by weight of such fine particles having a high transparency be incorporated in 100 parts by weight of the ionizing radiation curable resin described above. When less than 5 parts by weight of the fine particles are incorporated in 100 parts by weight of the ionizing radiation curable resin, the resulting protective layer 24a can not be cut cleanly when it is transferred to an image receiving material. . On the other hand, if more than 50 parts by weight of the fine particles are incorporated, the resulting protective layer 24a can not have a sufficiently high transparency. On the other hand, when other additives such as a wax, a lubricant, an ultraviolet absorber, an antioxidant and / or a fluorescent brightener are added to the protective layer 24a, an image transferred to a the image coated with the protective layer 24a has better sliding properties, gloss, light resistance, weather resistance,

whiteness and the like.

  The method described hereinafter can be used to form the protective layer 24a on the substrate sheet 2: an ink is prepared by adding a suitable solvent and the additives necessary for an ionizing radiation curable resin, and the viscosity of the mixture is adjusted ; the ink thus prepared is deposited on a substrate sheet by known means such as etching, reverse etching or roll coating processes, and is then dried and cured. The ionizing radiation curable resin is cured by application of radioactive radiation, such as

  ultraviolet rays or electron beams.

  Irradiation can be performed using a conventional technique as it is. For example, in the case where the hardening of the resin is carried out by applying an electron beam, an electron beam having an energy of 50 to 1000 keV, preferably 100 to 300 kev, emitted by an electron beam accelerator such as a Cockcroft-Walton accelerator, a Van de Graaff accelerator or a tuner-type accelerator, an insulator-core type accelerator, a linear accelerator or an electro-accelerator -rideau, dynamitron accelerator or accelerator

at high frequency.

  In the case where the curing of the resin is carried out by the application of ultraviolet rays, ultraviolet rays emitted by a light source such as a mercury vapor lamp at extra high pressure, high pressure or low pressure, or a carbon arc or xenon lamp, or a metal halide lamp. Curing of the resin by applying ionizing radiation may be performed either immediately after the ionizing radiation-curable resin ink has been deposited, or after the primer layer 24b, the ultraviolet absorber layer 24c and the adhesive layer 24d have been formed. In the latter case, the primer layer 24b can effectively avoid mixing or solvent etching that would be caused between the ionizing radiation curable resin ink to form the unprotected protective layer 24a and which is still soft and the ink used to form the absorber layer of the

ultraviolet 24c.

  The primer layer 24b which is a component of the transferable protective laminate 24 serves to improve the adhesion between the protective layer 24a described above and the absorber layer 24c. It can also serve as a barrier layer capable of preventing solvent attack or resin blending, which could be caused between the still uncured and still very soft protective layer and the absorber layer. ultraviolet light during

  formation of transferable protective laminate 24.

  Such a primer layer 24b can be formed by depositing a solution of an acrylic resin such as methyl methacrylate or ethyl methacrylate on the surface of the protective layer 24a by known means such as an etching process. reverse engraving or

  roll coating, and drying the deposited solution.

  The thickness of the primer layer 24b is about 0.1 to

5 micrometers.

  The ultraviolet absorber layer 24c, which is a component of the transferable protective laminate 24, serves to impart improved light resistance to an image.

  which has been transferred to a material for receiving the image.

  The ultraviolet absorber layer 24c is characterized by comprising a resin which is combined by reaction with a reactive ultraviolet absorber. However, it is possible to use a compound obtained by introducing, for example, an addition polymerizable double bond group, such as a vinyl, acryloyl or methacryloyl group, or an alcoholic hydroxyl, amino, carboxyl, epoxy or isocyanate group. in a non-reactive organic ultraviolet absorber known in the conventional art, such as an ultraviolet absorber of one of the following types: salicylate, benzophenone, benzotriazole,

  substituted acrylonitrile, chelating nickel or amide inhibited.

  More specifically, a reactive ultraviolet absorber having the following structural formula OH may be used

X-OCOC = CH.

o Rest H or CH3, and

X is -CH2CH2- or -CH2CH2-

  OH, or OH c Xc o R is H or CH3 and

X is -CH2CH2- or -CH2CHCH2-

  There are various methods for attaching the above-mentioned reactive ultraviolet absorber to a resin. For example, a resinous component such as a known reactive monomer, oligomer or polymer can be subjected, and the reactive ultraviolet absorber described above having an addition polymerizable double bond to a polymerization.

  radical to obtain a copolymer.

  On the other hand, in the case where the reactive ultraviolet absorber has a hydroxyl, amino, carboxyl, epoxy or isocyanate group, a thermoplastic resin with a reactive ultraviolet absorber is allowed to react with the reactive ultraviolet absorber.

  reactive group that can react with the reactive group

  above, in the presence, if necessary, of a catalyst, by application of heat or the like. The reactive ultraviolet absorber can thus be fixed to the resin

thermoplastic reaction.

  Examples of the monomer component which is copolymerized with the reactive ultraviolet absorber include the following substances: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, lauryltridecyl (meth) acrylate, tridecyl (meth) acrylate, cerylstearyl (meth) acrylate, stearyl (meth) acrylate, ethylhexyl (meth) acrylate, octyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, methacrylic acid, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, dimethylaminomethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, ethylene di (meth) acrylate, detylene glycol (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, decaethylene glycol ( meth) acryl ate, pentadecaethylene (meth) acrylate, pentacontahectaethylene glycol (meth) acrylate, butylene di (meth) acrylate, allyl (meth) acrylate, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol hexa (meth) acrylate, dipentaerythrolhexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol penta (meth) acrylate and phosphagen hexa (meth) acrylate. The compounds listed above may be used not only in the form of monomer but also in the form of oligomers. In addition, acrylic reactive polymers such as polyester acrylate polymers and epoxy acrylate polymers, which are polymers of the above compounds, or derivatives of the polymers, can also be used. These monomers, oligomers and reactive acrylic polymers can be used either alone or in combination. By copolymerizing the acrylic monomer, oligomer or reactive polymer described above with the reactive ultraviolet absorber, a thermoplastic copolymer resin can be obtained to which the reactive ultraviolet absorber is attached. The ultraviolet absorber layer 24c is

  formed by using this copolymer resin.

  The above copolymer resin contains 10 to 90% by weight, preferably 30 to 70% by weight of the reactive ultraviolet absorber. When a polymer resin containing less than 10% by weight of the reactive ultraviolet absorber, the resultant ultraviolet absorber layer 24c may not exhibit sufficiently high light resistance. On the other hand, when a copolymer resin containing more than 90% by weight of the reactive ultraviolet absorber is used, the coating solution used to form the ultraviolet absorber layer 24c becomes relatively tacky and image transferred to image receiving material, covered with protective laminate

transferable will be scrambled.

  The above copolymer resin has a molecular weight of about 5000 to 250000, in a more preferred mode, from about 9000 to 30000. When a copolymer resin having a molecular weight of less than 5000 is used, the The resultant ultraviolet absorber 24c is insufficient in film fastness. On the other hand, when a copolymer resin having a molecular weight of more than 250000 is used, the resultant ultraviolet absorber layer 24c does not cut cleanly when it is

  transferred to a receiving material of the image.

  The ultraviolet absorber layer 24c may also be formed by the combined use of the copolymer resin described above and a known organic ultraviolet absorber such as a benzophenone, benzotriazole, salicylate or amine ultraviolet absorber. inhibited, or a known inorganic ultraviolet absorber such as titanium oxide,

  zinc oxide or cerium oxide.

  The ultraviolet absorber layer 24c may be formed by known means, such as the reverse etching or roll coating method. The thickness of the ultraviolet absorber layer 24c is about 0.1 to 8

  micrometers, preferably from about 1 to 5 micrometers.

  The adhesive layer 24d, which is a constituent of the transferable protective laminate 24, can be formed in the same way as in the formation of the adhesive layer 14b of the transferable protective laminate 14 of the thermal transfer printing sheet 11 mentioned previously. We will therefore omit to give an explanation

of this layer.

  The heat fusible ink layer 27 contained in the zone 26 for transfer printing on the back of the thermal transfer printing sheet 21 is formed by laminating a nonstick OP layer 24a and a coloring ink layer 27b on the sheet of substrate 2, in that order. The transferable protective laminate 28 contained in the reverse transfer printing zone 26 is formed by laminating a protective layer 28a, a primer layer 28b, an ultraviolet absorber layer 28c and an adhesive layer 28d on the sheet. of substrate 2, in that order. The non-sticking OP layer 27a and the coloring ink layer 27b can be formed in the same way as in the formation of the non-stick OP layer 17a and the colorant ink layer 17b of the printing sheet by heat transfer 11 mentioned above. We therefore omit to give explanations for these layers. In addition, the protective layer 28a, the primer layer 28b, the ultraviolet absorber layer 28c and the adhesive layer 28d of the transferable protective laminate 28 may be formed in the same manner as in the formation of the protective layer 24a, the primer layer 24b, the ultraviolet absorber layer 24c and the adhesive layer 24d of the transferable protective laminate 24 described above. We therefore omit to give explanations for

these layers.

  Fig. 7 is a schematic sectional view showing the structure of the thermal transfer printing sheet 31 shown in Fig. 3. As shown in this figure, the thermal transfer printing sheet 31 has a zone 32 for printing by on-site transfer and an area 36 for reverse transfer printing which are provided alternately on one surface of a substrate sheet 2. On the other side, a reinforcing layer 3 is provided on the other side of the substrate sheet 2 The substrate sheet 2 and the reinforcing layer 3 are the same as those of the thermal transfer printing sheet 11 mentioned above. We will therefore fail to give

explanations here.

  Area 32 for in-place printing of the thermal transfer printing sheet 31 is a sublimable dye layer 33 (33Y, 33M, 33C), a hot meltable ink layer 34, and a transferable protective laminate 35. The sublimable dye layer 33 and the hot meltable ink layer 34 may be formed in the same manner as in the formation of the sublimable dye layer 13 and the hot melt ink layer 17 of the sheet thermal transfer printing apparatus 11, respectively. We therefore omit

  give here explanations for these layers.

  The transferable protective laminate 35 contained in the area 32 for spot transfer printing is formed by laminating a protective layer 35a, an ultraviolet absorber layer 35b and an adhesive layer 35c.

  on the substrate sheet 2, in that order.

  The protective layer 35a, which is a component of the transferable protective laminate 35, comprises, as a main constituent, a mixture of polymethyl methacrylate

(PMMA) and a wax.

  PMMA is excellent transparency and can produce a relatively strong film. It can therefore impart hardness and durability, such as scratch resistance and chemical resistance, to the protective layer 35a. Furthermore, since a wax is incorporated in the protective layer 35a, the transferable protective laminate 35 cuts cleanly when

  is transferred to an image receiving material.

  The wax incorporated in the protective layer 35a serves to impart to it slip properties. Examples of the wax that can be used include microcrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsh wax, and a variety of low molecular weight polyethylenes, Japanese wax, beeswax , spermaceti, insect wax, wool wax, shellac wax, candellia wax, petroleum jelly, partially modified waxes, fatty esters and amides

fat.

  It is preferable to use the wax described above in an amount of 1 to 20 parts by weight per 100 parts by weight of PMMA. When the wax is used in an amount of less than 1 part by weight per 100 parts by weight of PMMA, the resulting protective layer 35a can not

  not have a sufficiently high scratch resistance.

  On the other hand, when the wax is used in an amount of more than 20 parts by weight, the resulting protective layer 35a is of durability and transparency.

mediocre.

  It is also possible to incorporate in the protective layer 35 a substantially transparent inorganic or organic fine particles. When such fine particles are incorporated in the protective layer 35a, the transferable protective laminate 35 cuts more cleanly when heat-transferred to an image-receiving material and the scratch resistance and similar properties of the layer protector 35a are also improved. In addition, the surface gloss of the protective layer 35a is reduced, so that the protective layer will have a matte surface. Examples of the fine particles include those which have a relatively high transparency such as silica, Teflon powder, nylon powder. It is preferable to use the fine particles in an amount of 10 to 30% by weight of the PMMA. When the fine particles are used in an amount of more than 30% by weight of the PMMA, the resulting protective layer 35a has less transparency and

sustainability.

  In addition, when additives such as an ultraviolet absorber, an antioxidant and a fluorescent brightener are incorporated in the protective layer 35a, the image is transferred to an image-receiving material covered with the protective layer. 35a, has properties of gloss, lightfastness, resistance to

  weathering, and the like, improved.

  The protective layer 35a may be formed on the substrate sheet 2 as follows. An ink is prepared by mixing PMMA, wax and, if necessary, additives; the ink thus prepared is deposited on a substrate sheet by known means such as an etching process, reverse etching or roll coating, and then dried. The thickness of the protective layer 35a is about 10 microns, preferably about 0.1 to 5 microns. There is no particular limitation on the choice of the process used to mix PMMA and wax and it is possible to apply a process in which, after PMMA and wax have been melted separately, PMMA and the wax melted in a suitable organic solvent in which the two substances are soluble. A particularly preferred process is one in which a dispersion (or emulsion) of PMMA is mixed with a solution or dispersion (emulsion) of the wax. The dispersion (emulsion) obtained in this way is deposited on the substrate sheet 2 and then dried at a relatively low temperature (50 to 100 ° C.), so that at least a portion of the resin particles can remain in the state, thereby forming the protective layer 35a. Since some of the resin particles remain in this protective layer 35a, the surface of the protective layer 35a is rough and partially opaque. However, after being transferred to an image receiving material, the surface of the protective layer 35a is smooth and transparent because heat and pressure are applied to the protective layer to transport it to the receiving the image. In addition, since some of the resin particles remain in the protective layer 35a, the protective layer 35a cuts cleanly when it is thermally transferred to an image receiving material. The ultraviolet absorber layer 35b, which is a transferable protective laminate component 35, may be formed in the same manner as in the formation of the ultraviolet absorber layer 24c, which is a component of the transferable protective laminate 24 of the thermal transfer printing sheet 21 mentioned above. So we omit here to give an explanation of

this layer.

  The adhesive layer 35c, which is a component of the transferable protective laminate 35 of the thermal transfer printing sheet 31, serves to make the transferable protective laminate 35 easily transferable to an image receiving material. As adhesive component of the adhesive layer 35c, a hot-melt adhesive resin such as an acrylic resin, a vinyl chloride resin, a

  vinyl-vinyl acetate, an acrylic chloride terpolymer

  vinyl-vinyl acetate, a polyester resin, a polyamide resin. The adhesive layer 35c may be formed by known means. The thickness of the adhesive layer 35c is

  preferably from about 0.5 to 10 micrometers.

  On the other hand, it is also possible to incorporate in the adhesive layer 35c additives such as an antioxidant and a

fluorescent brightener.

  It is possible to render the structure of the thermal transfer printing sheet 41 according to the invention shown in FIG. 4 identical to that of the thermal transfer printing sheet 31, except that a transferable protective laminate 48 is formed on an area 46 for reverse transfer printing in the same manner as in forming the transferable protective laminate 35 provided on the area 32 for spot transfer printing of the thermal transfer printing sheet 31 described

upper.

  The transferable protective laminate 14, 24, 28 and 35 of different structures are shown in FIGS. 5 to 7. The transferable protective laminate of the thermal transfer printing sheet according to the invention can

  be of any of these structures.

All the thermal transfer printing sheets according to the invention which have been described above have a sublimable dye layer composed of sections of three colors yellow (Y), magenta (M) and cyan (C). However, the thermal transfer printing sheets according to the invention are not limited to these three colors and it is possible to provide a layer of sublimable dye of a desired color, depending on the use envisaged for the sheet.

  thermal transfer printing.

  <Double-sided transfer printing method according to the invention (one-roll type)> A double-sided transfer printing method using the thermal transfer printing sheet 11 shown in FIG. 1 will now be described. In this method, the thermal transfer printing sheet 11 is initially superimposed on an image receiving material by placing the sublimable dye layer 13Y of the thermal transfer printing sheet 11 and the surface of the printing material. receiving the image face to face. Heat and pressure are then applied to the thermal transfer printing sheet 11 by heating means such as a thermal head which emits heat in accordance with the image information, thereby transferring the yellow sublimable dye. on the surface of the image receiving material. This operation is repeated using the sublimable dye couchess 13M and 13C. On the surface of the image receiving material, a complete half-tone color image is formed. Then, the transferable protective laminate 14 is transferred from the thermal transfer printing sheet 11 to the desired portion of the surface of the image receiving material, so that a halftone image can be covered by transferable protective laminate 14. In this way, the transfer printing using the zone 12 for transfer printing on the spot of the sheet

  Thermal transfer printing 11 is complete.

  Then we return the image receiving material or we reverse the thermal printer. By this means, the thermal transfer printing sheet is superimposed on the image receiving material by placing the heat fusible ink layer 17 of the thermal transfer printing sheet 11 and the backside of the matter of receiving the image face to face. Next, heat and pressure is applied to the thermal transfer printing sheet 11 by heating means such as a thermal head which emits heat in accordance with the predetermined data, so that the layer of The heat-fusible ink 17 is transferred upside down from the image receiving material to form letters, symbols, or the like on the material. In this way, the transfer printing using the area 16 for reverse transfer printing of the thermal transfer printing sheet 11 is completed. By using the next pair of area-transfer printing area 12 and area 16 for reverse transfer printing of the thermal transfer printing sheet 11, double-sided transfer printing can be performed.

  the receiving material of the next image.

  A double-sided transfer printing method using the thermal transfer printing sheet 21 shown in FIG. 2 will now be explained. The thermal transfer printing sheet 21 is superimposed on the surface of a receiving material of the invention. image, and forming a full-color halftone image on the surface of the image-receiving material by using sublimable dye layers 23Y, 23M, and 23C in the same manner as in the method described above in which we

  uses the thermal transfer printing sheet 11.

  Then, the transferable protective laminate 24 of the thermal transfer printing sheet 21 is transferred to the desired portion of the surface of the image receiving material, so that the halftone image can be

  covered by the transferable protective laminate 24.

  The transfer printing using the zone 22 for transfer printing on the sheet

  thermal transfer printing 21 is thus completed.

  Then we return the image receiving material or we reverse the thermal printer. By this means, the thermal transfer printing sheet 21 is superimposed on the image receiving material by placing the hot meltable ink layer 27 of the thermal transfer printing sheet 21 and the backside of the the matter of receiving the image face to face. Then, heat and pressure is applied to the thermal transfer printing sheet 21 by a heating means such as a thermal head which emits heat in accordance with the predetermined data, so that the layer of The heat-fusible ink 27 is transferred upside down from the image-receiving material to form on this material line images such as letters, symbols or the like. Then, the transferable protective laminate 28 of the thermal transfer printing sheet 21 is transferred to the desired portion of the surface of the image receiving material, so that line images can be covered by the protective laminate. In this way, the transfer printing using the zone 26 for transfer printing on the back of the thermal transfer printing sheet 21 is completed. Using the next pair of area transfer printing zone 22 and area 26 for reverse transfer printing of the thermal transfer printing sheet 21, double-sided transfer printing can be performed on the matter of

receiving the next image.

  A double-sided transfer printing method using the thermal transfer printing sheet 31 shown in FIG. 3 will now be explained. The thermal transfer printing sheet 31 is superimposed on the surface of a receiving material of the invention. image, and forming a full-color halftone image on the surface of the image-receiving material by using the sublimable dye layers 33Y, 33M, and 33C in the same manner as in the method described above wherein the thermal transfer printing sheet 11 is then used. Next, the thermal transfer printing sheet 31 is superimposed on the image receiving material by placing the hot meltable ink layer 34 of the thermal transfer printing sheet 31 and the surface of the image receiving material facing each other. Heat and pressure are then applied to the thermal transfer printing sheet 31 by means of heating means such as a thermal head which emits heat at a predetermined temperature, so that the hot-meltable ink layer 34 is transferred to the surface of the image-receiving material to form on it images such as letters, symbols or the like. Then, the transferable protective laminate of the thermal transfer printing sheet 31 is transferred to the desired portion of the surface of the thermal transfer material.

  receiving the image so that at least the half image

  hue may be covered with the transferable transferable laminate 35. The transfer printing using the zone 32 for spot transfer printing of the sheet

  Thermal transfer printing 31 is thus complete.

  Then we return the image receiving material or we reverse the thermal printer. By this means, the thermal transfer printing sheet 31 is superimposed on the image receiving material by placing the hot meltable ink layer 37 of the thermal transfer printing sheet 31 and the backside of the the matter of receiving the image face to face. Next, heat and pressure is applied to the thermal transfer printing sheet 31 by heating means such as a thermal head which emits heat in accordance with the predetermined data, so that the layer of hot fusible ink 37 is transferred upside down from the image-receiving material to form on this material line images such as letters, symbols

  or the like. In this way, transfer printing

  zone 36 for reverse transfer printing of

  the thermal transfer printing sheet 31 is ter-

  undermined. Using the next pair consisting of area transfer printing area 32 and area 36 for reverse transfer printing of the thermal transfer printing sheet 31, double-sided transfer printing can be performed on the matter of

receiving the next image.

  A double-sided transfer printing process using the thermal transfer printing sheet 41 shown in FIG. 4 will now be explained. The thermal transfer printing sheet 41 is superimposed on the surface of a receiving material of the invention. image, and forming a full-color halftone image on the surface of the image-receiving material by using the sublimable dye layers 43Y, 43M, and 43C in the same manner as in the method described above in which we

  uses the thermal transfer printing sheet 11.

  Then, the thermal transfer printing sheet 41 is superimposed on the image receiving material, placing the hot meltable ink layer 44 of the thermal transfer printing sheet 41 and the surface of the material. receiving the image face to face. Heat and pressure are then applied to the thermal transfer printing sheet 41 by heating means such as a thermal head which emits heat in accordance with the predetermined data, so that the hot-melt ink layer 44 is transferred to the surface of the image-receiving material to form on it images such as letters, symbols or the like. Then, the transferable protective laminate 45 of the thermal transfer printing sheet 41 is transferred to the desired portion of the surface of the image receiving material, so that at least the halftone image can to be covered with the transferable protective laminate 45. The transfer printing using the area 42 for spot transfer printing of the thermal transfer printing sheet 41

is thus over.

  Then we return the image receiving material or we reverse the thermal printer. By this means, the thermal transfer printing sheet 41 is superimposed on the image receiving material by placing the hot meltable ink layer 47 of the thermal transfer printing sheet 41 and the backside of the matter of receiving the image face to face. Next, heat and pressure is applied to the thermal transfer printing sheet 41 by heating means such as a thermal head which emits heat in accordance with the predetermined data, so that the layer of hot melt ink 47 is transferred upside down from the image receiving material to form on this material letters, symbols or the like of the line. Then, the transferable protective laminate 48 of the thermal transfer printing sheet 41 is transferred to the desired portion of the back side of the image receiving material, so that the line images can be covered with the transferable protective laminate 48 In this way, the transfer printing using the area 46 for reverse transfer printing of the thermal transfer printing sheet 41 is completed. Using the next pair consisting of area 42 for spot transfer printing and area 46 for reverse transfer printing of the thermal transfer printing sheet 41, double-sided transfer printing can be performed on the matter of

receiving the next image.

  In any of the methods described above for double-sided transfer printing, using the thermal transfer printing sheet 11, 21, 31 or 41, the thermal transfer printing sheet is used without remain unused areas when thermal transfer printing is performed on the surface using the area transfer printing area, and on the back side of the image receiving material using the transfer printing area on back. The yield of the double-sided transfer printing performed using any of the methods according to

  the invention is therefore extremely high.

  In all of the two-sided transfer printing methods described above, an image is first formed on the surface of an image receiving material by using the area for transfer-in-place printing of the image sheet. thermal transfer printing. However, it is obvious that an image can be initially formed on the back of an image receiving material using

  the area for reverse transfer printing.

  <Double-sided transfer printing method according to the invention (two-roll type)> In all the double-sided transfer printing methods described above, only one thermal transfer printing sheet is used . We will now explain a double-sided transfer printing method according to the invention using two printing sheets per

Thermal transfer.

  Figs. 8 (A) and 8 (B) are plan views showing a pair of thermal transfer printing sheets for use in a double-sided transfer printing method according to the invention. A first thermal transfer printing sheet 51 shown in Fig. 8 (A) contains a sublimable dye layer 53 composed of sections (53Y, 53M, 53C) of three colors yellow, magenta and cyan, and a layer of ink hot fuse 54, which are provided alternately on a first face of a substrate sheet. The area of the hot-meltable ink layer 54 is twice as large as that of the section of each color of the sublimable dye layer 53. The first half 54a of the hot-melt ink layer 54 (FIG. half of the heat fusible ink layer 54 placed next to the sublimable dye layer 53) is used when an image is transferred to the surface of an image receiving material, and the second half 54b of the hot meltable ink layer 54 is used when an image is transferred upside down from the image receiving material. More specifically, the first thermal transfer printing sheet 51 has an area transfer printing area 52 composed of the sublimable dye layer 53 and the first half 54a of the hot melt ink layer 54 and a zone 56 for reverse transfer printing, composed of the second half 54b of the hot melt ink layer 54. It is possible to render these sublimable dye layers 53 and hot melt ink layer 54 identical to those of thermal transfer printing sheets according to the invention which have been mentioned above. On the other hand, a second thermal transfer printing sheet 58 shown in Fig. 8 (B) contains a transferable protective laminate 59 provided on a substrate sheet. It is possible to make this transferable protective laminate 59 identical to that of thermal transfer printing sheets according to

the invention mentioned above.

  The double-sided transfer printing method according to the invention using the first thermal transfer printing sheet 51 and the second thermal transfer printing sheet 58 is as follows. An image receiving material is first introduced into a thermal printer in which the first thermal transfer printing sheet 51 is placed, the first thermal transfer printing sheet 51 being superimposed on the receiving material. of the image by placing the sublimable dye layer 53Y of the thermal transfer printing sheet 51 and the surface of the image receiving material face to face. Heat and pressure are then applied to the thermal transfer printing sheet 51 by heating means such as a thermal head which emits heat in accordance with the image data, thereby transferring the sublimation dye. yellow on the surface of the material receiving the image. This is repeated using the sublimable dye layers 53M and 53C of the thermal transfer printing sheet 51. A full halftone color image is thus formed on the surface of the image receiving material. Next, the thermal transfer printing sheet 51 is superimposed on the image-receiving material by placing the first half 54a of the hot-melt ink layer 54 of the thermal transfer printing sheet 51 and the surface of the image receiving material face to face. Heat and pressure are then applied to the thermal transfer printing sheet 51 by means of heating means such as a thermal head which emits heat in accordance with the predetermined data, so that the hot-melt ink layer 54a is transferred to the surface of the image-receiving material to form on it images such as letters, symbols or the like. The transfer printing using area 52 for spot transfer printing of the first thermal transfer printing sheet 51 is

thus completed.

  Then, this image-receiving material is fed into a thermal printer in which the second thermal transfer printing sheet 58 is mounted such that the second thermal transfer printing sheet 58 is superimposed on the receiving the image by placing the transferable protective laminate 59 of the thermal transfer printing sheet 58 and the surface of the image receiving material facing each other. The transferable protective laminate 58 is then transferred to the desired portion of the surface of the image-receiving material, so that at least the halftone image can be covered with the protective laminate

transferable 58.

  Then, the image receiving material is returned or the thermal printer is reversed in which the first thermal transfer printing sheet 51 is mounted. The image receiving material is again introduced into this thermal printer so that the first thermal transfer printing sheet 51 is superimposed on the image receiving material by placing the second half 54b of the layer hot melt ink 54 of the first thermal transfer printing sheet 51 and the backside of the image receiving material facing each other. Heat and pressure are then applied to the first printing sheet by means of heating means such as a thermal head which emits heat in accordance with the predetermined data, so that Hot-melt ink 54b is transferred to the backside of the image-receiving material to form on this material line images such as letters, symbols, or the like. The heat transfer using the zone 56 for transfer printing on the back of the first thermal transfer printing sheet 51 is thus complete. Note that the following operation may also be performed: after the line images have been formed on the reverse side of the image receiving material using the first thermal transfer printing sheet 51, the the image receiving material in the thermal printer in which the second transfer printing sheet is mounted, and the transferable protective laminate 59 is transferred to the desired portion of the backside of the receiving material of the image, so that the line images can be

  covered with transferable protective laminate 58.

  In the double-sided transfer printing method described above, which uses the first thermal transfer printing sheet 51 and the second thermal transfer printing sheet 58 in combination, the thermal transfer printing sheets are used without remaining unused areas when the images are formed on both sides of the image receiving material. The yield of double-sided transfer printing performed by this method

so is extremely high.

  We will now explain another double-sided transfer printing method according to the invention which uses two

  thermal transfer printing sheets.

  Figs. 9 (A) and 9 (B) are plan views showing two thermal transfer printing sheets for use in a double-sided transfer printing method according to the invention. A first thermal transfer printing sheet 61 shown in Fig. 9 (A) contains a sublimable dye layer 63 composed of sections (63Y, 63M, 63C) of the three colors, yellow, magenta and cyan, a layer of ink hot fuse 64 and a transferable protective laminate 65, which are provided in sequence on a first surface of the substrate sheet. It is possible to produce these layers of sublimable dye 63 and heat-fusible ink 64 and the transferable protective laminate 65 identical to those of the thermal transfer printing sheets according to the invention mentioned above. Alternatively, a conventional thermal transfer printing sheet having the same structure as that of the first printing sheet can be used.

heat transfer 61.

  On the other hand, a second thermal transfer printing sheet 68 shown in Fig. 9 (B) contains a hot meltable ink layer 69 provided on a substrate sheet. It is possible to produce this layer of hot meltable ink 69 identical to that of the thermal transfer printing sheets according to the invention mentioned above. The double-sided transfer printing method according to the invention using the first thermal transfer printing sheet 61 and the second thermal transfer printing sheet 68 which have been described above is as follows. An image receiving material is first introduced into a thermal printer in which the first thermal transfer printing sheet 61 is mounted, so that the first thermal transfer printing sheet 61 is superimposed on the image receiving material, placing the sublimable dye layer 63Y of the thermal transfer printing sheet 61 and the surface of the image receiving material face to face. Heat and pressure are then applied to the thermal transfer printing sheet 61 by heating means such as a thermal head which emits heat in accordance with image data, thereby transferring the yellow sublimable dye to the surface of the image receiving material. This operation is repeated using the sublimable dye layers 63M and 63C of the first thermal transfer printing sheet 61. A full color image is thus formed on the surface of the image receiving material. Next, the first thermal transfer printing sheet 61 is superimposed on the image-receiving material by placing the hot-meltable ink layer 64 of the thermal transfer printing sheet 61 and the surface of the material. receiving the image face to face. Heat and pressure are then applied to the thermal transfer printing sheet 61 by heating means such as a thermal head which emits heat in accordance with the predetermined data, so that the ink layer Hot fuse 64 is transferred to the surface of the image receiving material to form on the latter line images such as letters, symbols and the like. Next, the first thermal transfer printing sheet 61 is superimposed on the image receiving material by placing the transferable protective laminate 65 of the first thermal transfer printing sheet 61 and the surface of the heat transfer printing material 61. the image face to face. The transferable protective laminate 65 is then transferred to the desired portion of the surface of the image-receiving material so that at least the halftone image can be covered with the transferable protective laminate 65. by transfer using the first printing sheet by

  heat transfer 61 is thus completed.

  Then, either the image receiving material is returned, or the thermal printer in which the second thermal transfer printing sheet 68 is mounted is reversed, relative to the thermal printer in which the first sheet of Thermal transfer printing 61 is mounted. The image receiving material is fed into the thermal printer in which the second thermal transfer printing sheet 68 is mounted, such that the second thermal transfer printing sheet 68 is superimposed on the thermal transfer printing material 68. receiving the image by placing the hot meltable ink layer 69 of the second thermal transfer printing sheet 68 and the backside of the image receiving material face to face. Heat and pressure are then applied to the thermal transfer printing sheet 68 by heating means such as a thermal head which emits heat in accordance with the predetermined data, so that the ink layer Hot fuse 69 is transferred upside down from the image receiving material to form on it line images such as letters, symbols or the like. Transfer printing using the second printing sheet per

  heat transfer 68 is thus completed.

  In the double-sided transfer printing method described above, which utilizes the first thermal transfer printing sheet 61 and the second thermal transfer printing sheet 68 in combination, the heat transfer sheets are used without the need for a thermal transfer sheet. there are still unused areas when the images are formed on both sides of an image receiving material. The yield of double-sided transfer printing performed by this method is therefore

extremely high.

  As described above in detail, a thermal transfer printing sheet according to the invention comprises a zone for transfer printing containing at least one layer of sublimable dye composed of sections of one or more colors. and a reverse transfer printing area containing at least one hot-melt ink layer composed of sections of one or more colors, the two areas being provided alternately on a first surface of a substrate sheet. In the double-sided transfer printing process according to the invention, which uses the thermal transfer printing sheet according to the invention, an image is formed on the surface of an image receiving material using the zone for in-place printing of the thermal transfer printing sheet and another image is formed on the reverse side of the image receiving material by using the reverse transfer printing area. Images can thus be formed on both sides of an image receiving material without leaving unused areas of the thermal transfer printing sheet. The yield of double-sided transfer printing is therefore remarkably increased and the cost of the operation can be

greatly reduced.

  In addition, by the combined use of a first thermal transfer printing sheet containing a hot meltable ink layer whose surface is twice as large as that of the sublimable dye layer, so that it can be used to form images on both surfaces of an image receiving material, and a second thermal transfer printing sheet containing a transferable protective laminate, or by the combined use of a first sheet of thermal transfer printing which can be used to form an image on the surface of an image receiving material and a second thermal transfer printing sheet which can be used to form an image on the backside of the image material receiving the image, images on both sides of an image receiving material can be formed using two different thermal printers without leaving unused areas on the sheets thermal transfer printing. The yield of double-sided transfer printing is considerably increased and the

  operating cost can thus be decreased.

Claims (15)

  A thermal transfer printing sheet useful for thermally transferring images on both sides of an image receiving material, characterized by comprising a substrate sheet (2); an area transfer printing area (12, 22, 32, 42) comprising at least one sublimable dye layer (13, 23, 33, 43) composed of sections of one or more colors; a reverse transfer printing area (16, 26, 36, 46) comprising at least one hot meltable ink layer (17, 27, 34, 44) composed of sections of one or more colors; and said two zones (12, 22, 32, 42 and 16, 26, 36, 46) being provided in   alternation on one side of the substrate sheet (2).   The thermal transfer printing sheet according to claim 1, characterized in that the area transfer printing area (12, 22, 32, 42) comprises the sublimable dye layer (13, 23, 33, 43). and a transferable protective laminate (14, 24, 34, 48). The thermal transfer printing sheet according to claim 2, characterized in that the area (16, 26, 36, 46) for reverse transfer printing comprises the fusible ink layer at   hot and a transferable protective laminate.   The thermal transfer printing sheet according to claim 1, characterized in that the region transfer printing area (42) comprises the sublimable dye layer, a layer   fusible ink and a transferable protective laminate (35).   The thermal transfer printing sheet according to claim 4, characterized in that the reverse transfer printing area (46) comprises the hot meltable ink layer and a   transferable protective laminate (48).   Thermal transfer printing sheet according to claim 1, characterized in that the sublimable dye layer (13,   23, 33, 43) is composed of sections of three colors, yellow, magenta and cyan.   Thermal transfer printing sheet according to claim 1, characterized in that the heat fusible ink layer (17,   27, 37, 47) is a black hot meltable ink layer.   Thermal transfer printing sheet according to claim 2, characterized in that the transferable protective laminate (14, 24, 28, 35, 45) is formed by laminating a protective layer and an adhesive layer on the protective layer. substrate, in this order, the protective layer comprising, as a main constituent, a mixture of an acrylic resin, a wax, a vinyl chloride-acetate copolymer, vinyl, and a polyester resin.   Thermal transfer printing sheet according to claim 2, characterized in that the transferable protective laminate (14, 24, 28, 35, 45) is formed by laminating a protective layer and a layer of adhesive on the sheet of substrate, in this order, the protective layer comprising, as a main constituent, a resin hardened by ionizing radiation.   Thermal transfer printing sheet according to claim 2, characterized in that the transferable protective laminate (14, 24, 28, 35, 45) is formed by laminating a protective layer and a layer of adhesive on the sheet of substrate, in this order, the protective layer comprising as a main constituent a mixture of   polymethyl methacrylate and a wax.   Thermal transfer printing sheet according to claim 2, characterized in that the transferable protective laminate (14, 24, 28, 35, 45) is formed by laminating a protective layer and a layer of adhesive on the protective layer. substrate, in this order, the protective layer comprising, as main constituents, a soluble resin   in water and insoluble particles in a solvent.   Thermal transfer printing sheet according to claim 2, characterized in that the transferable protective laminate (14, 24, 28, 35, 45) is formed by laminating a protective layer, an ultraviolet absorbing layer and a protective layer. adhesive on the substrate sheet, in this order, the ultraviolet absorbing layer comprising a polymer absorbing ultraviolet light.   Thermal transfer printing sheet according to claim 2, characterized in that the transferable protective laminate (14, 24, 28, 35, 45) is formed by laminating a protective layer and a layer of adhesive on the sheet of substrate, in this order and the adhesive layer comprising, as a main constituent, a vinyl chloride-vinyl acetate copolymer resin and / or a polymer absorbing ultraviolet light.   14. A two-sided transfer printing method of superimposing the thermal transfer printing sheet on the surface of an image receiving material, and applying heat and pressure to the sheet side of the image substrate of the thermal transfer printing sheet for producing images on both surfaces of the image-receiving material, characterized in that the thermal transfer printing sheet defined in claim 1 is superimposed on the surface of an image receiving material for performing the transfer printing using the area transfer printing area of the thermal transfer printing sheet, and the thermal transfer printing sheet is then superimposed on the back of the image receiving material to perform transfer printing using the transfer printing area   on the back side of the thermal transfer printing sheet.   15. A double-sided transfer printing method of superimposing the thermal transfer printing sheet on an image receiving material, and applying heat and pressure to the substrate sheet side of the sheet thermal transfer printing apparatus for producing images on both surfaces of the image-receiving material, characterized in that: the thermal transfer printing sheet defined in claim 1 is superimposed on the back side of a image-receiving material for performing the transfer printing using the back-transfer printing area of the thermal transfer printing sheet, and the thermal transfer printing sheet is then superimposed on the surface of the the image receiving material for performing the transfer printing using the transfer printing area   on location of the thermal transfer printing sheet.