JP3301434B2 - Film for lamination on metal plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film for laminating a metal can material such as soft drink, beer, and canned, which is used for heat resistance, beauty and rust prevention.

[0002]

2. Description of the Related Art Metal plates, such as steel and aluminum, are mainly used as metal cans for various soft drinks, beers, cans, and the like. Printing and coloring are applied.
Currently, printing and coloring methods for these containers are practically used, in which a metal plate is slit into a predetermined size and then printed by offset printing or the like and then printed, or a slit-formed cylindrical shape is formed. This is a method of performing printing and baking by offset printing or the like after bending and seam welding. Then, a metal container is obtained by performing flange processing, inside coating and baking, seaming processing, and the like.

However, in the method of printing directly on a metal material,
Neither printing on a flat plate, or printing after forming into a cylindrical shape, a printing method using a metal intaglio, such as gravure printing, cannot be used. This is because the metal material is hard and it is extremely difficult to make the metal intaglio uniformly contact the entire printing surface. Therefore, in the past, a plate having elasticity such as a rubber plate or a flexible resin plate has been used, but the printing accuracy when using such an elastic intaglio is poor, and it is difficult to obtain clear printing. In addition, it is difficult to perform complicated printing that requires a wide range of gradation settings such as halftone printing and photographic printing, and only plain printing and coloring are actually performed.

[0004] In order to enable more beautiful and three-dimensional printing, multiple printing using a large number of paints is required. However, drying and baking of the printing ink takes a long time. When such multiple printing is incorporated into the can-making process, there arises a problem that the drying and baking of the printing ink is rate-limiting and the can-making speed becomes extremely slow. Therefore, the number of overprints that can be practically used on an industrial scale is naturally limited, and printing with satisfactory sharpness and aesthetic design cannot be obtained.

A method of offset printing on a slit-processed metal plate is also known, but it is still difficult to perform halftone printing and the like, and printing with satisfactory sharpness and aesthetic design cannot be obtained. Then, it is the same as the case of the gravure printing.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made to eliminate the above-mentioned problems pointed out when directly printing a metal plate processed into a plate or a cylinder. As a completely new technology, a clear and beautifully printed film is laminated on a metal plate to obtain a high-quality decorative metal plate, or this metal plate is formed into a can shape to form a decorative metal plate. We have developed a method for obtaining containers and are working on practical research.

However, the laminated metal sheet is subjected to considerable high heat treatment such as seam welding and flange processing when post-processing containers and the like, or subsequent boiling processing and retorting processing after enclosing the contents. The film is thermally damaged, causing whitening, embrittlement, or unevenness due to shrinkage, and the like, which has the disadvantage that the appearance of the printed surface is impaired.

The present invention has been made in view of the above circumstances, and has as its object the purpose of the present invention, such as deformation due to embrittlement or shrinkage even when subjected to a considerable amount of heat in the post-processing step as described above. An object of the present invention is to provide a film for laminating on a metal plate, which can maintain a clear and beautiful print state without causing the problem.

[0009]

Means for Solving the Problems The structure of the laminating film according to the present invention which can solve the above problems is as follows.
Polyester is a main component, and a polyester-polyether block copolymer is added to the polyester in an amount of 0.1% in terms of a polyether component.
1 to 10% by mass and having a base layer composed of a polyester-based film having a glass transition temperature of 60 ° C. or higher and a cured heat-resistant layer having a thickness of 0.5 to 5 g / m ² as the outermost surface layer The gist exists.

In the laminating film of the present invention, the above-mentioned cured heat-resistant layer is formed on one side of the upper base layer, or the above-mentioned cured heat-resistant layer is formed via a printing ink layer. For example, the cured heat-resistant layer constituting the outermost surface layer functions as a protective layer for the base layer and the printing ink layer. In particular, in the present invention, since the cured heat-resistant layer having a predetermined thickness is formed as the outermost layer constituting layer, the surface can be protected from heat.

When the can is made by a conventional method with the lamination surface side of the laminated metal plate facing outward, a metal container having a beautiful body can be obtained.

[0012] Further, a polyester-based film is laminated via an adhesive layer made of a curable resin on the surface of the laminated metal plate opposite to the surface on which the print layer is formed, and the resulting double-sided laminate is obtained. When the metal plate is made with the laminated surface of the film on which the printing ink layer is formed on the outside, the metal container having the outer surface side of the body beautiful and the inner surface coating layer formed thereon can be obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is based on a method in which a laminating film is preliminarily printed and then laminated on a metal plate. Not only becomes possible, but printing is performed on a soft film, so clear printing using metal intaglio etc. becomes possible, and halftone printing, photographic printing, or multicolor printing with three-dimensional appearance is also easy. And high-quality decorative printing can be achieved. Therefore, if this laminating method is adopted, various effects can be obtained as will be described later, as compared with the conventional method in which printing is directly performed on a metal plate after can making.

The basic structure of the laminating film according to the present invention is, for example, as shown in FIG. 1 (partly enlarged sectional view), in which a printing ink layer 2 is provided on one side of a polyester film layer 1 as a base layer. On the opposite side, a cured heat-resistant layer 4 constituting the outermost surface layer is formed. The adhesive layer 3 made of a curable resin is used on the metal plate Me by a dry laminating method or a thermal laminating method. Laminated.

Here, the polyester film layer 1 serves as a base film on which the printing ink layer 2 is formed, enables clear and beautiful multiple printing, and performs a bending process during can manufacturing after lamination. It has moderate flexibility so that it can be easily performed, and furthermore, seam welding and flange processing at the time of can making, inside coating treatment after can making,
Polyester-polyether block copolymer (B) is added to polyester (A) in an amount of 0 in terms of polyether component as a material capable of withstanding high heat received in boiling treatment performed after enclosing the contents or retort treatment or the like. .
1 to 10% by mass, and glass transition temperature is 60 ° C
The polyester film described above is used.

Specific examples of the polyester-polyether block copolymer (B) include, for example, block copolymers of aromatic polyesters such as polyethylene terephthalate, polyethylene terephthalate and polyethylene naphthalate with polytetramethylene glycol ether and polyethylene glycol ether. Polymers. Among these, other components include acid components such as isophthalic acid, naphthalenedicarboxylic acid, adipic acid and sebacic acid; glycol components such as propylene glycol, butanediol and neopentyl glycol; and oxycarboxylic acids such as p-oxybenzoic acid. A small amount of an acid component or the like may be copolymerized.

Examples of the polyester (A) include polyethylene terephthalate and polyethylene naphthalate. Of these, polyethylene naphthalate is particularly preferred. The polyester (A) also
As other components, the same acid component and glycol component as described above,
It may contain an appropriate amount of an oxycarboxylic acid component or the like.

The mixing ratio of the polyester-polyether block copolymer (B) to the polyester (A) is set in the range of 0.1 to 10% by mass (the ratio to the whole polyester film) in terms of the polyether component. When the blending amount of the polyester-polyether block copolymer (B) is insufficient, the heat resistance of the film becomes insufficient, and the film is whitened or embrittled by heat during post-processing, or undergoes heat shrinkage. As a result, blister-like irregularities are generated, and the beauty of the printed surface is impaired. However, if the amount is too large, the laminate film shrinks,
In addition, in the laminating stage, the printing pitches become inconsistent due to deformation, resulting in a remarkable increase in the processing failure rate. In addition, since sink occurs due to shrinkage and shift from a predetermined laminating position, it must be suppressed to 10% by mass or less. The more preferable blending amount of the polyester-polyether block copolymer (B) is in the range of 0.2 to 3.5% by mass in terms of the polyether component.

As described above, the most preferable polyester (A) in which the polyester-polyether block copolymer (B) is blended is polyethylene naphthalate. In order to more effectively prevent thermal deformation and the like, the content of polyethylene naphthalate in the total amount of the polyester film is preferably set to 10 to 99.9% by mass.

In the present invention, as described above, by using a polyester-based film obtained by blending a specific amount of the polyester-polyether block copolymer (B) with the polyester (A), whitening as a laminate film can be achieved. It suppresses embrittlement and thermal deformation, etc., and keeps the printing ink layer provided on the film clear and beautiful. For example, when used as a container for retort products, the whitening phenomenon at the time of hot water treatment is more surely prevented. In order to prevent this, the intrinsic viscosity of the polyester (A) is 0.57 to
It is preferable to use a polyester having a ratio of 1.7, more preferably 0.6 to 1.5, and still more preferably 0.65 to 1.1.

The polyester film preferably has a melting point of about 175 ° C. or higher, and the peak temperature of shrinkage stress after lamination on a metal plate is higher than the highest temperature that is received during post-processing after lamination. Low,
In addition, it is preferable that the internal stress of the laminated film before molding is 0.25 kg / mm ² or less at the maximum temperature at which it is subjected to post-processing, usually 120 to 350 ° C.
If a polyester film that satisfies these requirements is used, pinhole defects may occur due to heat received during seam welding and flange processing during can making, inside coating processing after baking, boiling processing, retort processing, etc.
The film melts or softens and shrinks to lose its smoothness or lose its luster.Moreover, it is more reliable to generate defects such as blister-like irregularities, stress cracks, delamination, and whitening due to crystallization in the film. Can be prevented.

This polyester-based film layer 1 is shown in FIG.
When the printing ink layer 2 is formed inside the film layer 1 as shown in (1), the printing ink layer 2 should be transparent so that the printing ink layer 2 can be seen through from the outer surface side.

Next, the printing ink layer 2 is not particularly special, and can be formed using any type of printing ink used for conventional packaging films and the like.
The formation may be performed according to a conventional method, but more preferably, use of a heat-resistant ink of a curable type.

The adhesive layer 3 formed on the laminating surface side with the metal plate M is firmly joined to the metal plate M by a dry lamination method, a thermal lamination method, or the like. It is made of a curable resin that is cured by heat or light so that the bonding strength is not lost due to boiling or retort treatment. Specific examples of the adhesive layer 3 include an epoxy resin, a polyurethane resin, a polyester resin, a polyester polyurethane resin, an isocyanate resin, and various modified resins thereof. It is preferable that the adhesive layer 3 is formed in advance, and then completely cured in a state of being laminated on the metal plate M.

Further, in the present invention, as shown in the figure, since the cured heat-resistant layer 4 is formed on the outermost surface side of the polyester film layer 1, the heat resistance of the laminating film is remarkably enhanced. That is, as described above, a polyester-based compound resin having high heat resistance is used as the polyester-based film layer 1 on which the printing ink layer 2 is provided. However, the heat is still higher than the melting point of the resin, for example, the maximum melting point peak temperature. When a heat history at a temperature of Tm + 5 ° C. or more with respect to (Tm) is received in post-processing, the polyester film layer 1 softens or undergoes thermal deterioration, or becomes white due to heat treatment or retort treatment after the contents are enclosed. Although a phenomenon may be caused to impair the beauty, if the cured heat-resistant layer 4 is formed on the surface of the polyester-based film layer 1 as shown in the illustrated example, the cured heat-resistant layer 4 functions as a heat-resistant protective layer. In addition, it is possible to more reliably prevent deformation, whitening, and the like associated with thermal deterioration and softening of the polyester film layer 1. Therefore, in the present invention, which must be protected by the cured heat-resistant layer 4, the polyester-based film layer 1
It is also possible to use a resin having a relatively low softening point.

Since the cured heat-resistant layer 4 functions as a protective layer on the outermost surface side, for example, as shown in FIG. 2 can also be formed.

The constituent materials of such a cured heat-resistant layer 4 include:
Softening point or decomposition temperature of 250 ° C or higher, more preferably
It is better to use one with a temperature of 300 ° C or higher.
Resin, epoxy resin, urea resin, acrylic resin
Resin, urethane resin, unsaturated polyester resin,
Such as liquefied resins or their various modified resins
Various curing reactive resins or UV curable resins
Can be used. But preferably, printing inks
Does not impair the aesthetics provided by layer 2
You should use a transparent one. And its thickness
0.5 to 10 g / m ^Two, Preferably 0.5 to 5 g / m^Twoof
Range, and if it is too thin, the surface protection
It is difficult to be exhibited in minutes, while if it is too thick, it hardens during bending
Cracks are easily generated in the heat-resistant layer 4.

The laminating film of the present invention is a laminated film having a laminated structure of at least two or more layers, and is laminated on a metal plate by a dry laminating method or a thermal laminating method as described above. At this time, for example, as shown in FIG. 3, if a method of laminating a transparent or colored coat layer (or primer layer) 5 in advance on the laminating surface side of the metal plate M and then laminating is adopted, The adhesion to the film can be further enhanced, and the laminating speed can be further increased.

In particular, it is preferable that the coating layer 5 is colored, since the background color of the metal plate is thereby concealed, the sharpness provided by the printing ink layer 2 is further improved, and the lamination strength is also increased. The color of the coat layer 5 formed as a base layer may be appropriately selected according to the coloring of the printing ink layer 2.
It is preferable because the uniformity of the printing ink layer 2 of any color can provide an excellent sharpness improving effect.

When the thus obtained laminating film is laminated on a metal plate or a metal plate on which a coat layer is formed by the above-described method, a beautified metal plate can be obtained. Not only can it be used as it is as various panel materials and decorative outer panel materials, but if it is made according to a conventional method, a very beautiful and highly designable metal container can be obtained.

In the above description, the method of utilizing the excellent coloring and color tone provided by the printing ink layer for beautifying the outer surface of a metal container or the like has been described. Can also be used effectively. However, the inside coat is intended to prevent corrosion of the inner surface of the metal container or elution of metal ions, and it is not necessary to improve the beauty by forming the printing ink layer. Therefore, a polyester film provided with a printing ink layer is laminated on the surface side of the metal plate,
On the opposite side of the metal plate (that is, on the side corresponding to the inner surface side of the metal container), a double-sided laminated metal plate obtained by similarly laminating a polyester film having corrosion resistance and an effect of preventing metal ion elution is printed. If you can make the laminated film with the ink layer on the front side,
The metal container having the inside coat layer formed thereon can be obtained in a single step, and the inside-coating treatment after can making can be omitted.

FIG. 4 shows an example of a double-sided lining metal plate having such a configuration. An adhesive layer 3, a printing ink layer 2, a polyester film layer 1,
A laminate layer composed of the cured heat-resistant layer 4 is formed, and a polyester film layer 1a on which the cured heat-resistant layer 4a is formed is laminated on the opposite side via an adhesive layer 3a.

As the polyester film constituting the inside coat layer, a normal polyester film can be used because the appearance is not particularly degraded due to whitening or the like, but the same heat resistance can be given to the inside coat layer. In the sense, the same polyester as described above-
It is desired to use a polyester film blended with a polyether block copolymer, particularly a film mainly composed of polyethylene naphthalate or the like.

The present invention is configured as described above. The features of the present invention are summarized below in comparison with the conventional method of printing and printing directly on a metal plate.

(1) Realization of high-quality printing The method of printing directly on a metal plate lacks sharpness as described above, and it is difficult to perform halftone printing and photographic printing, and only monotonous printing can be obtained. However, in the present invention, since a method of printing on a flexible polyester-based film and then laminating the same is used, the sharpness of printing is high, and halftone printing, photographic printing, and the provision of a three-dimensional effect by multiple printing are easy. This makes it possible to print a wide range of colors and colors with a luxurious feel.

(2) Achieving high-speed printing In the conventional method, as described above, the time required for drying or curing of the printing ink determines the rate of the can-making process. Therefore, the can-making speed cannot be sufficiently increased. In this case, a printed laminating film is prepared in advance, and can be brought into a can-making line to be continuously laminated on a metal plate, so that the speed of can-making can be significantly increased.

(3) Improvement of glossiness In the conventional method, gloss can be increased to some extent by forming an overcoat layer after printing and baking on a metal plate. However, the overcoat layer has a fine-grained coating. It is difficult to obtain satisfactory gloss because the coating layer surface has fine irregularities due to heat shrinkage during drying. On the other hand, in the present invention, a polyester film mixed with a polyester-polyether block copolymer is used as a film substrate for lamination, and a cured heat-resistant layer is formed as the outermost layer. , Embrittlement, deformation due to heat shrinkage, etc. can be prevented, and if necessary, a film with high smoothness can be obtained by treating with a mirror-finished roll in the manufacturing process of the laminating film. In addition to stretching acting on the film, the outer surface side is slightly stretched in each subsequent bending process, so that the smoothness of the outermost surface of the laminated film in a can-making state is further enhanced, and extremely excellent gloss can be obtained. In particular, in the present invention, since the cured heat-resistant layer is formed as the outermost surface layer of the laminating film, it does not lose its gloss even when exposed to a high temperature near the melting point of the base film and is extremely sharp. Beautiful appearance is maintained.

(4) Improvement of scratch resistance and antifouling property In the case of the conventional example, the ink layer printed on the hard metal is easily damaged by scratching or the like, and the printing ink tends to fall off. Since the hardened heat-resistant layer is formed as the outermost surface layer, it is possible to prevent the ink from falling off, scratching, and the like. In addition, contamination of the printing ink layer due to spilled contents (liquids such as beverages and soups) and external contaminants does not occur.

(5) Cost reduction of a metal plate or a metal container which has been beautified In a method of printing on a metal plate or a cylindrical molded product thereof, if a printing error occurs, all of the printed metal plate or the cylindrical molded product is lost. Becomes defective. In other words, a loss occurs after reaching a high value-added state. However, in the present invention, the quality can be selected at the printing stage on the polyester film, and the printing technology on the resin film has been extremely advanced, the defective product occurrence rate is extremely low, and even if a printing error occurs. Since the added value is low, the loss can be minimized. In addition, since printing on a film and lamination of the film on a metal plate can be performed at a high speed, high-speed production is possible, and from such a viewpoint, the product price can be reduced.

(6) Support for multi-product production In the conventional example, once printing is performed on a metal plate or the like,
Although it can be used only for the purpose, the laminating film of the present invention can be similarly laminated on other metal plates and molded bodies as long as it is of the same size, and it can be used not only for mass production of the same kind but also for various kinds It is easy to cope with small production.

(7) Improvement of heat discoloration resistance A polyester film blended with a specific amount of a polyester-polyether block copolymer is used as a film substrate for lamination, and a cured heat-resistant layer is formed as the outermost surface layer. Therefore, even when the laminate film layer receives considerable heat during seam welding and flange processing during can making, boiling treatment and retort treatment after can making, the laminated film layer may become cloudy, discoloration, embrittlement, color unevenness, etc. Never wake up. Further, even when subjected to a high-temperature heat history, the surface does not undergo uneven deformation due to heat shrinkage, bubbles, floating, etc., and a clear and beautiful appearance is maintained.

(8) The back side is also laminated with a polyester film heat-reinforced by a cured heat-resistant layer.
By making the can with the laminated surface side of the film on which the printing ink layer is formed on the outside, the inside coat layer can be formed at the same time as the can making, and the inside coating process after can making can be omitted. Becomes

Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted by the following Examples. Are all included in the technical scope of the present invention.

[0044]

EXAMPLES Example 1 and Comparative Example 1 Polyethylene terephthalate having an intrinsic viscosity of 0.80 (glass transition temperature: 65 ° C.) and a polyethylene terephthalate-polytetramethylene glycol ether block copolymer were mixed with polytetramethylene glycol ether. A film having a thickness of 12 μm (200 μm) obtained by blending so that the content as a component is 4% by mass, forming a film, and biaxially stretching the film.
Shrinkage stress at 0.5 ° C .: 0.5 kg / mm ² )
The composition obtained by mixing the alkyd resin and the lubricant is 2 g / solid content.
The coating was cured to give m ² and cured to form a cured heat-resistant layer. Next, after printing is performed on the surface of the film opposite to the cured heat-resistant layer, an adhesive (a mixture of polyurethane adhesive “Adcoat” manufactured by Toyo Ink Co., Ltd. and a curing agent) is solidified on the printing ink layer. It was coated at 4 g / m ^{2 in} terms of minutes, dried and aged at 40 ° C. for 24 hours to obtain a film for lamination.

As Comparative Example 1, the intrinsic viscosity was 0.58
Comparative Laminating Film was obtained in exactly the same manner as above except that the polyethylene terephthalate biaxially stretched film was used.

Each of the obtained laminating films and a biaxially stretched film made of polyethylene terephthalate having an intrinsic viscosity of 0.80 (glass transition temperature: 65 ° C.) and having the same adhesive layer provided on one surface for lamination. Using a film, these were laminated on both sides of a degreased cold-rolled steel sheet by a thermal lamination method to obtain a double-sided laminated steel sheet.

Using this laminated steel plate, a metal container for a soft drink was prepared by a conventional method with the laminated surface of the film on which the printing ink layer was formed facing outside, and the outer surface side body portion of the obtained container was laminated. The surface had a clear, glossy, beautiful appearance and excellent gloss, and an inner / outer laminated metal container having a polyester film as an inside coat layer was obtained on the inner surface.

In the above can making step, heat of 270 ° C. or more was applied to the laminating film. As a result, it is considered that the polyester film of the film is molten, but since it is protected by a cured heat-resistant layer made of an alkyd resin, almost no shrinkage deformation, decrease in gloss, and deterioration of the printing ink layer are recognized. I couldn't. In addition, this container
The film was treated with hot water at 0 ° C. and steam at 125 ° C., but no turbidity or thermal deterioration of the film layer for lamination was observed, and the beautiful appearance was not impaired. No deterioration was observed in the inside coat layer on the inner surface side of the can.

On the other hand, in Comparative Example 1, when the temperature was 280 ° C. or higher, there was a slight tendency that the free end of the film and the squeezed portion of the neck portion and the like tended to be raised or uneven. According to the present invention, these problems were solved. It turns out that it can be prevented. Further, in Comparative Example 1, the printed surface became cloudy, the gloss was lost, and the color tone was lacking in sharpness, and the free end of the film at the joint was uneven due to thermal deformation.

Comparative Example 2 The same procedure as in Example 1 was repeated except that polyethylene terephthalate
The film was formed and biaxially stretched in the same manner as in Example 1 except that the polytetramethylene glycol ether copolymer was blended so that the content as the polytetramethylene glycol ether component was 15% by mass. Thickness 1
2 μm film (shrinkage stress at 200 ° C .: 0.03 k
g / mm ² ). When the obtained film was used and heat of 270 ° C. or more was applied to the metal laminate obtained in the same manner as in Example 1, the gloss of the printed surface decreased despite the presence of the cured heat-resistant layer on the surface. In addition, the surface lost its smoothness and became a crack-like surface. The film at the end of the laminate shrank and moved from the initial position, and partially peeled off. Moreover, it was confirmed that wrinkles were easily formed in the laminating step, and that elongation deformation occurred when tension was applied. Further, in the subsequent heating step, it was found that the printed pattern was reduced from the initial pitch, and that the pattern could not be put to practical use despite the low stress.

[0051]

The present invention is constituted as described above. As described in the above (1) to (8), the laminate film layer has excellent heat resistance and the outermost surface layer has Because it is protected by a hardened heat-resistant layer with a predetermined thickness, it does not become cloudy or degrade in appearance due to thermal deformation even when subjected to a high-temperature treatment at or above the melting point of the base resin. It is possible to provide a beautiful metal plate or a metal container with a high quality feeling that is easy to give a feeling and the like under low cost with excellent productivity, and furthermore, without dropping of printing ink or scratching, and It has become possible to provide a laminating film that provides a decorative metal plate and a decorative metal container having high gloss and excellent stain resistance and heat resistance.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing a laminated structure of a laminating film according to the present invention.

FIG. 2 is an explanatory sectional view showing a laminated structure of another laminating film according to the present invention.

FIG. 3 is an explanatory sectional view showing a laminated structure of still another laminating film according to the present invention.

FIG. 4 is a cross-sectional explanatory view illustrating a double-sided laminated metal plate using the laminating film of the present invention.

[Explanation of symbols]

 1,1a Polyester film layer 2 Printing ink layer 3,3a Adhesive layer 4,4a Curable heat-resistant layer 5 Coat layer (or primer layer) M Metal plate

Claims (5)

(57) [Claims] 1. A polyester film comprising a polyester as a main component, a polyester-polyether block copolymer in an amount of 0.1 to 10% by mass in terms of a polyether component, and a glass transition temperature of 60 ° C. or higher. A film for laminating on a metal plate, comprising a base layer formed as described above and a cured heat-resistant layer having a thickness of 0.5 to 5 g / m ² as the outermost surface layer. 2. The laminating film according to claim 1, wherein the cured heat-resistant layer is formed on one side of the base layer, and an adhesive layer made of a curable resin is formed on the other side. 3. The laminating film according to claim 1, wherein the cured heat-resistant layer is formed on one side of the base layer via a printing ink layer. 4. The laminating film according to claim 1, wherein the cured heat-resistant layer has a softening point or a decomposition temperature of 250 ° C. or higher. 5. The laminating film according to claim 1, wherein the polyester film contains 10 to 99.9% by mass of polyethylene naphthalate.