JP3246522B2 - Laminated substrate for sublimation type thermal transfer image receiving sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated substrate for a sublimation type heat transfer image receiving sheet.

[0002]

2. Description of the Related Art As an image receiving sheet used in a sublimation type thermal transfer recording system, an image receiving layer comprising a thermoplastic polyester resin or the like having a strong dyeing property with respect to a heat sublimation dye and a release agent is used. The one formed above is used. However, an image receiving sheet using a single layer of synthetic paper or a plastic film as a substrate tends to curl due to heat at the time of transfer by a thermal head, and the running property in a thermal transfer recording apparatus is insufficient. there were. As an improvement, a laminated substrate of synthetic paper / cellulose fiber paper / synthetic paper (JP-A-62-198497)
However, although the use of such a material has less curl than a conventional substrate such as synthetic paper, the effect of improving curl in a high density (high applied energy) portion is not sufficiently exhibited. In addition, the present applicant has previously proposed a substrate in which two films are laminated via a pressure-sensitive adhesive layer or an elastic adhesive layer,
Although the curl is less than that of a conventional substrate such as synthetic paper, the curl improvement in a high density (high applied energy) portion is still insufficient. Further, a film is adhered to both the front and back surfaces of the sheet-like support via an adhesive layer, and the adhesive layer on the surface side on which the image receiving layer is formed is made of a pressure-sensitive adhesive or an elastic adhesive. Although a laminated substrate for a sheet has been previously proposed, when the heat shrinkage of the film to be bonded is large (synthetic paper, foamed polypropylene, etc.), the curl improvement in a high concentration (high applied energy) portion is still insufficient.
Furthermore, when the heat shrinkage of the film to be bonded is small (transparent or white PET film, etc.), the curl in the high density (high applied energy) portion is good, but the cushioning property of the bonded film is poor, so that it is low. Insufficient sensitivity and white spots occur in the density (low applied energy) area.

[0003]

SUMMARY OF THE INVENTION The present invention solves the conventional drawbacks, significantly reduces the curl generated by heat during image recording by a thermal head, and further improves the image quality in a low-density portion with good dot reproducibility. An object of the present invention is to provide an improved laminated substrate for a sublimation type thermal transfer image receiving sheet.

[0004]

According to the present invention, a film is adhered to both the front and back surfaces of a sheet-like support via an adhesive layer, and at least the surface on which an image receiving layer is formed is adhered. In the laminated substrate for a thermal transfer image receiving sheet in which the agent layer is composed of an adhesive or an elastic adhesive, at least the surface film on which the image receiving layer is formed is JIS C
A laminated substrate for a thermal transfer image receiving sheet is provided which is a film containing fine bubbles having a heat shrinkage ratio of not more than 6% in both the vertical and horizontal directions according to −2318. Further, at least the film on the surface side on which the image receiving layer is formed is a foamed film having a heat shrinkage of 2.5% or less in both the vertical and horizontal directions according to JIS C-2318. The laminated substrate for a sublimation type thermal transfer image receiving sheet is provided. Further, there is provided the laminated substrate for a sublimation type thermal transfer image receiving sheet, wherein the film on the front side is a polyethylene terephthalate film.

[0005] The laminated substrate for a sublimation type thermal transfer image receiving sheet of the present invention has the above-mentioned structure, and thus has the following effects. 1) A film is adhered to both front and back surfaces of a sheet-like support constituting the substrate via an adhesive layer, and at least the adhesive layer on the surface side on which the image receiving layer is formed is a pressure-sensitive adhesive or an elastic adhesive. The image receiving layer during printing,
The heat shrinkage of the film on the front side can be absorbed by the stress relaxation of the pressure-sensitive adhesive or the elastic adhesive, and the curl amount can be reduced. In addition, at least the film on the surface side on which the receiving layer is formed has a heat shrinkage rate of 6% or less in both the vertical and horizontal directions according to JIS C-2318, so that a high density (high applied energy) portion is obtained. In this case, the heat shrinkage of the film itself on the front side can be reduced, and as a result, the curl amount of the entire receiving paper can be reduced. Further, by forming a foamed film on at least the film on the surface side on which the image receiving layer is formed, the cushioning property is improved, the adhesion between the ink layer and the image receiving layer is improved, and the dots in the low density (low applied energy) portion are formed. The reproducibility can be improved, and as a result, insufficient sensitivity and white spots can be prevented. 2) By setting the heat shrinkage rate of at least the surface side film on which the receiving layer is formed to 2.5% or less in both the vertical and horizontal directions according to JIS C-2318,
The heat shrinkage of the film on the surface side in the high density (high applied energy) portion can be reduced, and as a result, the curl amount of the entire receiving paper can be further reduced. 3) A film using foamed PET as the surface side film is not only inexpensive, but also excellent in the heat shrinkage of the film itself, and also excellent in whiteness as a substrate, so that the heat shrinkage reduction treatment can be performed. There is no need for steps such as addition of a fluorescent whitening agent or white pigment for whiteness adjustment. 4) The reason for limiting to the adhesive layer at least on the front side and the film at least on the front side is as follows. image
When recording, the image receiving layer of the receiving sheet and the sublimation recording
Sublimation by superimposing the ink layer of the photo object facing
Recording is performed by heating from the back of the recording medium with a thermal head.
You. Since heat is transmitted from the sublimation recording medium to the receiving sheet side,
The opposite side of the receiving sheet is the opposite backing sheet
Higher temperature. For this reason, the high temperature receiving layer and the front side
The sheet shrinks more than the lower back sheet
Because of the pan, the balance of shrinkage is lost, causing curl
be able to. In the present invention, the heat shrinkage rate
Use a small amount of sheet and curl the adhesive layer on the front side
The use of an adhesive or elastic adhesive to alleviate
The amount of metal can be reduced. These effects
By limiting the sheet and adhesive on the front side,
Expand your choice of body and back sheets and adhesives
So that the support and back sheet are limited
No need.

Next, the present invention will be described in more detail with reference to the drawings. FIG. 1 shows a laminated substrate 6 according to the present invention, in which a front-side foamed film 2 is laminated and adhered on a surface of a support 1 via an adhesive layer 4, and on a back surface of the support 1. Is obtained by laminating and bonding the back side film 3 via the adhesive layer 5. FIG. 2 shows an image receiving sheet in which an image receiving layer 7 is formed on the front side film 2 of the laminated substrate 6 according to the present invention.

The image receiving layer 7 may have a single layer structure or a multi-layer structure. Further, a layer (thermal fusion preventing layer) for preventing thermal fusion with an image transfer medium (ink sheet) not shown may be provided on the image receiving layer 7. An intermediate layer may be provided between the front-side film 2 and the like for the purpose of improving adhesion or the like, or a layer for preventing charge may be provided on the image receiving layer 7 or the thermal transfer preventing layer. A back coat layer for preventing blocking and double feed may be provided on the back side film 3.

Examples of the sheet-like support 1 used for the laminated substrate of the present invention include paper such as high-quality paper, medium-quality paper, Japanese paper, thin paper, and coated paper (including finely coated paper and art paper). , Polyester, polyvinyl chloride, polyolefin,
Synthetic resin films such as nylon and cellophane can be used. The sheet-like support 1 used for the laminated substrate of the present invention preferably has a thickness of 20 to 300 μm. If the thickness is less than 20 μm, the rigidity of the obtained image receiving sheet becomes weak, and it becomes impossible to sufficiently prevent the curl generated during image recording. On the other hand, if the thickness exceeds 300 μm, the thickness of the obtained image receiving sheet becomes excessively large, and the running property of the image receiving sheet in the printer is reduced and the number of sheets to be accommodated is undesirably reduced. The sheet-like support 1 preferably has a heat shrinkage rate of 3% or less in both the vertical and horizontal directions according to JIS C-2318.

Examples of the film used for the backside film 3 of the laminated substrate of the present invention include a polyethylene film, a polypropylene film, a polyvinyl chloride film, a polyvinylidene chloride film having no voids or voids therein. Polyvinyl alcohol film,
Polyethylene terephthalate film, polycarbonate film, nylon film, polystyrene film, ethylene-vinyl acetate copolymer film, ethylene-vinyl alcohol copolymer film, polyethylene naphthalate film, fluorinated ethylene propylene film, aromatic polyamide film, polyarylate film And plastic films such as polyethersulfone films, polyetherimide films, polyimide films, acrylic resin films, and ionomers.

The foamed film used for the front-side film 2 of the laminated substrate and having a heat shrinkage of 6% or less in both the vertical and horizontal directions according to JIS C-2318 has the above-mentioned voids. Examples of the film include a film having a void subjected to a heat shrinkage reduction treatment, for example, a heat (heat set) treatment. Examples of the heat shrinkage reduction treatment include a method in which an untreated film is brought into contact with a heat roll and heated. By performing the treatment, the stress at the time of stretching held in the film can be relaxed, and the heat shrinkage can be reduced. The materials of the front side film 2 and the back side film 3 may be the same or different.

The film having voids can be obtained by a method of extruding a resin with an orifice together with a foaming agent to form a film, a method of adding fine particles to the resin, and stretching the resin to generate voids. Examples of the film having voids obtained by adding fine particles to a resin and stretching the film include a biaxially stretched multilayer structure film mainly containing a mixture of a polyolefin and an inorganic pigment. The polyolefin resin constituting such a stretched multilayer structure film is generally selected from a polyethylene resin and a polypropylene resin, and the inorganic pigment is selected from titanium dioxide, calcium carbonate and the like. The content of the inorganic pigment in the film is suitably about 3 to 80% by weight. The structure of the stretched film is composed of a base layer made of an inorganic pigment-containing polyolefin resin, and a paper-like layer made of a monoaxially or biaxially stretched inorganic pigment-containing polyolefin resin film attached to the front and back surfaces thereof. It may be a four-layer structure or a four-layer structure such as a three-layer structure, or a four-layer structure including the base layer, the paper-like layer, and another layer such as a surface layer having improved whiteness. Absent.

Film (stretched film) in the present invention
In Nos. 2 and 3, when the heat shrinkage rate according to JIS C-2318 is set to 2.5% or less in both the vertical and horizontal directions, the curl generated during the printing operation of the high energy portion by the thermal transfer method is further reduced. It is particularly preferable because it can be performed. Also, specifically, foamed PET is inexpensive, and at the same time, has excellent heat shrinkage of the film itself,
Furthermore, since the whiteness of the substrate is excellent, it is particularly preferable because steps such as a heat shrinkage reduction treatment and addition of a fluorescent whitening agent or a white pigment for whiteness adjustment are not required. The thickness of both the front side film 2 and the back side film 3 is 4 to 250 μm, preferably 9 to 150 μm.
m.

In the laminated substrate of the present invention, the sheet-like support 1 and the front side film 2 are laminated and adhered via the adhesive 4. The adhesive layer 4 here is formed by coating a pressure-sensitive adhesive or an elastic adhesive by a known method. The "adhesive" is one of the adhesives, and together with the "elastic adhesive", has a lower cohesive force and a faster absorption and relaxation of stress than other adhesives. For this reason, in the image receiving sheet using the laminated substrate of the present invention, the shrinkage stress of the image receiving layer 7 or the front side film 2 generated by heat at the time of image recording by the thermal head is reduced by the pressure-sensitive adhesive layer or the elastic adhesive. Is absorbed into the sheet-like support 1
Also, the curl of the image receiving sheet can be made extremely small by utilizing the rigidity of the backside film 3.

As the adhesive for forming the adhesive layer 4, any conventionally known adhesive can be used. Since the adhesive has a viscoelastic behavior, it is basically based on a polymer. The compounding ratio actually varies depending on the application, but basically, the two components of the polymer elastic body and the tackifier are used as a skeleton, and in order to impart various resistances, a tackifier, an adhesion improver, and other additives are used. Used.

The polymer used as the polymer elastic body includes natural rubber, styrene-butadiene copolymer, isoprene copolymer, chloroprene copolymer, acrylate copolymer, vinyl-ether copolymer, and the like. EVA resin, polyisobutylene, polyurethane, siloxane crosslinked polymer and the like can be mentioned.

As the tackifier, rosin, dammar,
Tackifying resins such as copearl, water-point rosin, coumarone indene resin, polyterpene, phenolic resin, alkyd resin, petroleum hydrocarbon resin, xylene resin, epoxy resin; plasticizers such as phthalate ester, phosphate ester, and paraffin chloride Softening agents such as animal and vegetable oils and mineral oils; In addition, antioxidants, stabilizers, coloring agents, and the like are used as needed as additives.

On the other hand, as the elastic adhesive forming the adhesive layer 4, any known elastic adhesive can be used. In particular, the Young's modulus of the adhesive layer formed from the elastic adhesive is 1 to
It is preferably 2,000 kg / cm ² . The elastic adhesive contains a polymer elastic material as a main component, and an adhesion improver, an antioxidant, and a stabilizer are used as needed to impart various heat resistances. Among the above-mentioned elastic adhesives, an elastic adhesive containing a synthetic rubber or a siloxane crosslinked polymer as a main component is particularly preferable because of its high ability to absorb stress.
Examples of the elastic adhesive containing a siloxane cross-linked polymer as a main component include, for example, a liquid polymer containing an amino group capable of reacting with epoxy, having a main chain structure of polyoxypropylene and having a moisture-curable silyl group, and an epoxy resin. And a composition mainly composed of

The viscosity of the pressure-sensitive adhesive or elastic adhesive is adjusted by adding water or an organic solvent to the above-mentioned adhesive, if necessary, and then the adhesive layer 4 is applied to the adhesive layer 4 by a conventional method such as a coating method or a hot melt coating method. It is formed on a sheet-like support 1. The thickness of the adhesive layer 4 is about 1 to 60 μm, preferably 5 to 60 μm.
μm to 50 μm. When the thickness is less than 1 μm, the effect of preventing curling is poor. On the other hand, when the thickness is more than 60 μm, troubles such as protrusion of the pressure-sensitive adhesive or elastic adhesive from the laminated substrate may occur.

As the adhesive for forming the adhesive layer 5, any conventionally known adhesive or pressure-sensitive adhesive can be used. Specifically, urea resin, melamine resin, phenol resin, epoxy resin, vinyl acetate resin , Vinyl acetate / acrylic copolymer resin, EVA meter resin, acrylic resin, polyvinyl ether resin, vinyl chloride / acetic acid copolymer resin, polystyrene resin, polyester resin, polyurethane resin, polyamide resin, poly Chlorinated polyolefin resin, polyvinyl butyral resin, acrylate resin, methacrylate copolymer,
A natural rubber-based, cyanoacrylate-based, silicone-based adhesive or the like, or an appropriate tackifier may be added to these adhesives to use the adhesive. The adhesive layer 5 may further include a plasticizer, a filler, an antioxidant, and the like, if necessary.

Therefore, the adhesive layer 5 is adjusted to the viscosity by adding water or an organic solvent to the above-mentioned adhesive component, if necessary, and is coated on a sheet-like support by a conventional method.
And the back side film 3 are laminated and adhered via the adhesive layer 5. The thickness of the adhesive layer 5 is suitably about 1 to 40 μm.

[0021]

Next, the present invention will be described more specifically with reference to examples. Parts here are by weight.

Example 1 A foamed polypropylene film (trade name: YP56;
Thickness: about 48 μm, thermal shrinkage: about 5% in length and width, manufactured by Toray Industries, Inc.
A laminated substrate for an image receiving sheet of the present invention was prepared by laminating and adhering to both sides of a sheet-like support made of a T film (trade name: E20; manufactured by Toray Industries, Inc.) by a dry lamination method. An acrylic pressure-sensitive adhesive (trade name: Polycic 370-S; manufactured by Sanyo Chemical Industries, Ltd.) was used to attach the front-side support to the film, the thickness of the pressure-sensitive adhesive layer was about 3 μm, and the back-side support was used. A polyester adhesive (trade name: S-3911; manufactured by Toa Gosei Chemical Co., Ltd.) was used for adhesion between the body and the film, and the thickness of the adhesive layer was about 3 μm.

Example 2 A foamed polypropylene film (trade name: YP56;
Thickness: about 48 μm, heat shrinkage: 2.6% length, 2.8 width
%, Manufactured by Toray Industries, Inc.)
m on a sheet-shaped support made of a white PET film (trade name: E20; manufactured by Toray Industries, Inc.), and laminated and adhered to both surfaces by a dry lamination method to prepare a laminated substrate for an image receiving sheet of the present invention. An acrylic pressure-sensitive adhesive (trade name: Polycic 370-S; manufactured by Sanyo Chemical Industries, Ltd.) was used to attach the front-side support to the film, the thickness of the pressure-sensitive adhesive layer was about 3 μm, and the back-side support was used. A polyester adhesive (trade name: S-3911; manufactured by Toa Gosei Chemical Co., Ltd.) was used for adhesion between the body and the film, and the thickness of the adhesive layer was about 3 μm.

Example 3 A foamed polyethylene terephthalate film (trade name: E60, thickness: about 50
μm, heat shrinkage: 1.0% length, 1.8% width, manufactured by Toray)
This film was laminated and adhered to both sides of a sheet-like support made of a white PET film (trade name: E20; manufactured by Toray Industries, Ltd.) having a thickness of about 100 μm to prepare a laminated substrate for an image receiving sheet of the present invention. . An acrylic ester copolymer-based pressure-sensitive adhesive (trade name: Olivine BPS5454; manufactured by Toyo Ink Co., Ltd.) was used for adhering the support and the film on the front and back surfaces, and the thickness of the pressure-sensitive adhesive layer was about 3 μm each. .

Comparative Example 1 A foamed polypropylene film (trade name: YP56, thickness: about 48 μm, heat shrinkage: 6.6% in length, 7.0% in width, manufactured by Toray Industries, Inc.) was used as the film on the front and back sides. This film was laminated and adhered to both sides of a sheet-like support made of a white PET film (trade name: E20; manufactured by Toray Industries, Ltd.) having a thickness of about 100 μm by a dry lamination method. A substrate was prepared. An acrylic pressure-sensitive adhesive (trade name: Polycic 370-S; manufactured by Sanyo Chemical Industries, Ltd.) was used to attach the front-side support to the film, the thickness of the pressure-sensitive adhesive layer was about 3 μm, and the back-side support was used. A polyester adhesive (trade name: S-391) is used for bonding the body and the film.
1; manufactured by Toa Gosei Chemical Co., Ltd.), and the thickness of the adhesive layer was about 3 μm.

Comparative Example 2 A white polyethylene terephthalate film (trade name: E20, thickness: about 50 μm) was used as the film on the front side and the back side.
m, heat shrinkage ratio: 1.4% length, 0.4% width, manufactured by Toray Industries, Inc.), and this film is made of a white PET film having a thickness of about 100 μm (trade name: E20; manufactured by Toray Industries, Inc.). By laminating and adhering to both sides of the body, a laminated substrate for an image receiving sheet of the present invention was prepared. An acrylic ester copolymer-based pressure-sensitive adhesive (trade name: Olivine BPS5454; manufactured by Toyo Ink Co., Ltd.) was used for adhering the support and the film on the front and back surfaces, and the thickness of the pressure-sensitive adhesive layer was about 3 μm each. .

Subsequently, the following image-receiving layer coating solution was coated on the laminated substrate with a wire bar, dried at a drying temperature of 80 ° C. for 1 minute, and then subjected to an aging treatment at 60 ° C. for 2 hours to obtain a layer having a thickness of about 60 ° C. An image receiving sheet was formed by laminating a 3 μm image receiving layer. (Solution for receiving layer) Saturated copolymerized polyester resin (trade name: Byron 200; manufactured by Toyobo Co., Ltd.) 100 (trade name: AY42-125; manufactured by Toray Dow Corning Silicone Co., Ltd.) 5 Solvent Toluene 300 Methyl ethyl ketone 300 On the other hand, silicone resin-based heat-resistant layer The following coating liquid for an ink layer was applied to a thickness of 2.0 μm on a 6 μm-thick PET film having a thickness of 1 μm using a wire bar and dried to prepare a sublimation transfer recording material. (Coating liquid for yellow ink layer) Polyvinyl butyral resin (trade name BX-1; manufactured by Sekisui Chemical Co., Ltd.) 10 Sublimation dye for yellow (trade name: Yellow VP; manufactured by Mitsui Toatsu Dye Co., Ltd.) 4 Solvent Toluene 95 Methyl ethyl ketone 95 (Magenta ink Coating solution for layer) Polyvinyl butyral resin (trade name BX-1; manufactured by Sekisui Chemical Co., Ltd.) 10 Sublimation dye for magenta (trade name Magenta VP; manufactured by Mitsui Toatsu Dye Co., Ltd.) 10 Solvent Toluene 95 Methyl ethyl ketone 95 (Coating for cyan ink layer) Liquid) Polyvinyl butyral resin (trade name BX-1; manufactured by Sekisui Chemical Co., Ltd.) 10 Sublimation dye for cyan (trade name: Cyan VP; manufactured by Mitsui Toatsu Dye Co., Ltd.) 10 Solvent Toluene 95 Methyl ethyl ketone 95 Obtained sublimation transfer recording medium and image The receiving sheet is composed of the ink layer of the sublimation transfer recording material and the image receiving layer of the image receiving sheet. Superposed as facing, yellow by changing the heating energy in the thermal head from the back of the sublimation recording medium, magenta, performs superimposed sequentially recording cyan, to obtain a black solid image. The recording density of the thermal head was 12 dots / m.
m, and the applied energy was 0.64 mj / dot. The degree of curl of the image receiving sheet after image recording was examined, and the results are summarized in Table 1.

[0028]

[Table 1] (Note) The image receiving sheet (A4 size) after recording was placed on a flat desk with the recording surface facing upward, and the height from the flat surface to the recording surface was measured, and the maximum value was shown.

[0029]

The laminated substrate for a sublimation type thermal transfer image receiving sheet of the present invention comprises a sheet-like support constituting the substrate and a film adhered to both front and back surfaces of the substrate via an adhesive layer. By forming at least the surface-side adhesive layer formed of an adhesive or an elastic adhesive, the image-receiving layer at the time of printing, the heat shrinkage of the film on the surface side is absorbed by the stress relaxation of the adhesive or the elastic adhesive, thereby curling. The amount can be reduced. Further, by setting the heat shrinkage rate of at least the surface side film on which the receiving layer is formed to 6% or less in both the vertical and horizontal directions according to JIS C-2318, the high density (high applied energy) portion can be obtained. The heat shrinkage of the film on the front side can be reduced, and as a result, the curl amount of the entire receiving paper can be reduced. In addition, by setting the heat shrinkage rate to 2.5% or less in both the vertical and horizontal directions, the heat shrinkage rate of the film itself on the surface side in the high-density (high applied energy) portion is further reduced. The curl amount of the entire receiving paper can be further reduced. Furthermore, since the film on at least the surface side on which the image receiving layer is formed is a foamed film, the cushioning property is improved so that the adhesion between the ink layer and the image receiving layer is improved, and the low density (low applied energy) is achieved. It is possible to improve the dot reproducibility in the portion, and consequently prevent insufficient sensitivity and white spots from occurring. Furthermore, when foamed PET is used as the foamed film, the foamed PET is inexpensive, has excellent heat shrinkage of the film itself, and also has excellent whiteness as a substrate. There is no need for a step of lowering or adding a fluorescent whitening agent or a white pigment for whiteness adjustment.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a laminated substrate for a sublimation type thermal transfer image receiving sheet of the present invention.

FIG. 2 is a schematic cross-sectional view of a sublimation type thermal transfer image receiving sheet having an image receiving layer formed on a surface side film of a laminated substrate of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sheet-like support body 2 Front side film 3 Back side film 4 Adhesive layer (adhesive layer or elastic adhesive layer) 5 Adhesive layer 6 Laminated substrate 7 Image receiving layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroki Kuboyama 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Yutaka Aruga 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (56) References JP-A-2-38089 (JP, A) JP-A-3-55295 (JP, A) JP-A-3-234588 (JP, A) JP-A-3-266691 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (3)

(57) [Claims] A film is adhered to both front and back surfaces of a sheet-like support via an adhesive layer, and at least the surface-side adhesive layer on which the image receiving layer is formed is formed of a pressure-sensitive adhesive or an elastic adhesive. In the laminated substrate for a thermal transfer image receiving sheet, at least the film on the surface side on which the image receiving layer is formed has a vertical heat shrinkage ratio in accordance with JIS C-2318,
A laminated substrate for a sublimation type thermal transfer image receiving sheet, characterized in that it is a film containing fine bubbles of 6% or less in any transverse direction. 2. The film on at least the surface side on which the image receiving layer is formed is a foamed film having a heat shrinkage according to JIS C-2318 of 2.5% or less in both the vertical and horizontal directions. The laminated substrate for a sublimation type thermal transfer image receiving sheet according to claim 1, wherein: 3. The laminated substrate for a sublimation type thermal transfer image receiving sheet according to claim 1, wherein the film on the front side is a polyethylene terephthalate film.