JP3205271B2 - Transfer foil film - 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 a transfer foil, and more particularly, to a film useful as a support film for a transfer foil for in-mold transfer (in-mold transfer foil) for transfer printing simultaneously with molding in injection molding or the like. It relates to a polyester film.

[0002]

2. Description of the Related Art Conventionally, as an in-mold transfer foil,
A laminated film in which a polyester film such as a polyethylene terephthalate film or the like is used as a base film, a release layer (medium layer) is provided on the surface of the base film, and a printing layer is further coated thereon.

[0003] This in-mold transfer foil is peeled off and separated between the release layer surface and the print layer surface after transfer. That is, after the molding transfer, the printing layer adheres to the surface of the molded article and is taken out as a product, and the release layer is removed after molding in a state of being laminated on the base film.

[0004] However, the conventional in-mold transfer foil has an insufficient adhesive force between the release layer and the base film or an insufficient release property between the release layer surface and the print layer surface. In many cases, peeling occurs between the surface of the release layer and the surface of the base film in the release treatment after the transfer of the molding, and the release layer remains on the surface of the molded article together with the printed layer and is often taken out. Such defects are often caused by peeling of the release layer and the base film due to distortion when the laminated film is deformed in in-mold molding transfer.

[0005] To improve this point, a method of improving the adhesion between the base film and the release layer by providing an adhesive layer made of polyester resin, polyurethane resin, acrylic resin or the like between the base film and the release layer. Is valid. However, the resin constituting the adhesive layer is usually molecularly designed from the viewpoint of adhesive properties and has low solvent resistance. For this reason, when coating the release layer, the adhesive layer that has been dissolved or softened by the solvent is partially peeled off by the release layer coating tool, and the adhesive strength between the release layer and the base film is reduced. A new problem arises. In addition, a film having an adhesive layer laminated thereon has a disadvantage that the films are liable to stick to each other (poor blocking resistance), which impairs the handling properties when a release layer is further laminated on this film.

In addition, the in-mold transfer foil is formed by
During the transfer printing process, it is three-dimensionally deformed from a flat state to the same shape as a molded product. At that time, if the moldability of the base film is low, the transfer foil cannot be sufficiently deformed and stretched at the time of molding, and sometimes the transfer foil may be torn, thereby impairing the appearance of the molded product, Troubles such as improper transfer of the print layer occur.

As a method for preventing such troubles, a method for improving the moldability of a base film by reducing the molecular orientation and crystallinity of the film, for example, by setting a stretching temperature, a magnification, and other heat treatment temperatures during film formation. Methods for optimization are known. However, when the adhesive layer is formed in the film forming step by this method, there is a problem that the base film and the adhesive layer are separated during the film forming process depending on the type of the resin constituting the adhesive layer.

[0008] In recent years, printed patterns formed and transferred have become more delicate and complicated. The state of the printing surface before molding transfer is usually confirmed through the opposite surface (base film surface) of the printing surface. However, the base film of the conventional molding transfer foil often has a low light transmittance, so complex patterns and characters can be printed. It is difficult to confirm.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to prevent the release layer and the base film from peeling during molding transfer, to provide excellent adhesiveness at the time of molding, to provide excellent handleability and moldability of the film, Another object of the present invention is to provide a transfer foil film having excellent visibility during printing.

[0010]

According to the present invention, there is provided a dicarboxylic acid component having a metal base, which is dispersed in a coating material as fine particles having an average particle diameter of 100 to 20 nm on at least one surface of a polyester film. 2 to 8 mol
%, Using a coating composition containing a copolymerized polyester having a secondary transition point of 40 to 85 ° C. as a main solid component, a coating layer having a dry coating thickness of 0.05 to 0.3 μm,
And dF10 / dS of the film is 0.10 to 0.30K
g / mm ² /% elongation.

In the present invention, the polyester forming the base film is a crystalline linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Specific examples of such polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,
6-naphthalenedicarboxylate and the like can be exemplified. These include copolymers or blends of these with small proportions of other resins. Among them, polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate are particularly preferred.

These polyesters may contain organic or inorganic fine particles as required. As such fine particles, those usually added to a polyester film are used, for example, inorganic fillers such as silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin, talc, titanium oxide, zinc oxide, barium sulfate, etc. An organic filler made of a heat-resistant resin such as a silicone resin, a crosslinked polystyrene resin, a crosslinked acrylic resin, a urea resin, a melamine resin, and the like can be given. In addition, other resins such as polyethylene, polypropylene, ethylene-propylene terpolymer, and olefin-based ionomers, coloring agents, antistatic agents, catalysts, stabilizers, antioxidants, ultraviolet absorbers, and fluorescent brighteners are required. It can also be contained if necessary.

In the present invention, the polyester film comprises
What is necessary is just to have the thickness used as a film for transfer foils, Preferably it is 10-150 micrometers, Especially preferably, it is 2 micrometers.
0 to 100 μm.

In the present invention, the polyester film comprises:
DF10 / dS is 0.10~0.30Kg / mm ² / elongation%, and particularly preferably 0.15~0.25Kg / mm ² / elongation%. Here, dF10 / dS is the slope of the film at the time of 10% elongation in the film elongation curve. This dF10 / dS is 0.30 kg / mm ²
If it exceeds /% of elongation, the stress at the time of molding increases, which may cause a trouble such as tearing. 0.10K
If it is less than g / mm ² / elongation%, the surface properties, heat resistance and dimensional stability of the film are undesirably deteriorated.

In the production of such a polyester film,
The amorphous unstretched film is stretched 2.0 to 4.0 times, preferably 2.5 to 3.5 times in the machine direction at a temperature of 60 to 130 ° C., preferably 90 to 125 ° C., and then at a temperature of 60 to 130 ° C. in the transverse direction. ~
130-C, preferably 2.0-4.0 at 90-125C.
It is preferably stretched by a factor of, preferably 3.0 to 4.0 times. The area magnification after biaxial stretching is preferably 13 or less. The unidirectional stretching may be performed in two or more stages. However, after stretching in the biaxial direction, an intermediate heat treatment is performed, and then the same direction as the first stage and / or the same as the second stage is performed. It may be stretched in the direction. In these cases, the final stretch ratio is preferably within the above range.

The heat setting after the stretching is preferably performed at a temperature higher than the final stretching temperature and lower than the melting point for a time of 1 to 30 seconds. For example, in the case of a polyethylene terephthalate film, it is preferable to heat-fix at a temperature of 150 to 250 ° C. and a time of 2 to 30 seconds. At this time, the contraction or elongation within 20%, or the treatment under a fixed length, or the treatment may be carried out in two or more stages.

In the present invention, at least one side of the polyester film is dispersed as fine particles having an average particle diameter of 100 to 20 nm in a coating composition and has a secondary transition point obtained by copolymerizing 2 to 8 mol% of a dicarboxylic acid component having a metal base. 40 ~
A coating layer having a dry coating thickness of 0.05 to 0.3 [mu] m is provided by using a coating material containing 85 [deg.] C copolymerized polyester as a main solid component.

The above-mentioned copolymerized polyester has an average particle diameter of 100 to 20 nm, preferably 80, in a coating agent, especially an aqueous coating agent.
It has the property of forming fine particles of up to 20 nm. This fine-grained copolyester does not take the form of fine particles by forming a film by coating and drying, but if the average particle size exceeds 100 nm, the influence of the particle shape remains, and the unevenness on the surface of the coating film. It is not desirable because it is formed or its frequency is so large that the light transmittance is lowered, making it difficult to observe the printed surface through the base film. On the other hand, if it is less than 20 nm, the blocking resistance tends to be insufficient, which is not desirable.

The copolymerized polyester further has a secondary transition point (Tg) of 40 to 85 ° C., preferably 45 to 80 ° C.
It has the characteristics of ° C. Tg of copolymerized polyester is 40 ° C
When the temperature is less than 85 ° C., the resulting film is inferior in heat resistance and blocking resistance.

Further, this copolymerized polyester is a linear polyester comprising a dicarboxylic acid component and a polyol component, and containing a dicarboxylic acid component having a metal base as a 2 to 8 mol% copolymerized component. When the copolymerization ratio of the dicarboxylic acid component having a metal base is less than 2 mol%,
This is disadvantageous because the solvent resistance of the coating layer becomes too high and the solvent resistance is lowered. On the other hand, if it exceeds 8 mol%, the blocking resistance is poor, which is not desirable. When the proportion of the copolymer component is 4 to 8 mol%, the copolymerized polyester becomes an aqueous polyester having good dispersibility in water,
It is preferable because the blocking resistance is further improved.

The dicarboxylic acid having a metal base is used in the acid compound in a SO ₃ M group or a COOM group (M is Na, K, L
i, those having a functional group such as NH _4, etc.), specific examples 5-Na sulfoisophthalic acid, 5-ammonium sulfoisophthalate, 4-Na sulfoisophthalic acid,
4-methylammonium sulfoisophthalic acid, 2-Na
Sulfoisophthalic acid, 5-K sulfoisophthalic acid, 4-
K sulfoisophthalic acid, 2-K sulfoisophthalic acid, N
a sulfonate alkali metal salt or sulfonate amine salt compounds such as sulfosuccinic acid, etc., trimellitic anhydride, trimellitic acid, pyromellitic anhydride, pyromellitic acid, trimesic acid, cyclobutanetetracarboxylic acid,
Examples include dimethylolpropionic acid and the like, and monoalkali metal salts thereof. The free carboxyl group is converted to a carboxylate group by the action of an alkali metal compound or an amine compound after copolymerization. Of these,
Those having a sulfonic acid metal base are preferable, and those having a sulfonic acid alkali metal base are more preferable.

In the present invention, the dicarboxylic acid component other than the dicarboxylic acid component having a metal base, which forms the copolymerized polyester, includes terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid,
Examples thereof include 4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, phenylindanedicarboxylic acid, and dimer acid. Two or more of these components can be used. Furthermore, maleic acid,
Unsaturated polybasic acids such as fumaric acid and itaconic acid and p-
Hydroxybenzoic acid, p- (β-hydroxyethoxy)
A small proportion of hydroxycarboxylic acid such as benzoic acid can be used. The proportion of the unsaturated polybasic acid component or hydroxycarboxylic acid component is at most 10 mol%, preferably 5 mol% or less.

The polyol component forming the copolymerized polyester includes ethylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol. , Xylylene glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, poly (ethyleneoxy) glycol, poly (tetramethyleneoxy) glycol, an alkylene oxide adduct of bisphenol A, and the like. It is preferable to use two or more of these. Among such polyol components, ethylene glycol, an alkylene oxide adduct of bisphenol A, and 1,4-butanediol are preferred.

Further, as the copolymerized polyester resin, a modified polyester copolymer, for example, the polyester copolymer described above may be used in the form of acryl, polyurethane, silicone, epoxy,
A block polymer modified with a phenol resin or the like, or a graft polymer can also be used.

These copolymerized polyesters are preferably used in the form of an aqueous dispersion or emulsion to form a coating layer. In order to form a coating layer, in addition to the copolymerized polyester, other resins, a colorant, an antistatic agent, a catalyst, a stabilizer, a surfactant, an antioxidant, an ultraviolet absorber and the like are contained as necessary. You can also.

In the above coating layer, filler particles satisfying the following formula (1), preferably the following formula (2), are contained in an amount of 0.1 to 2:
It is preferably contained at 0% by weight, more preferably 0.1 to 12% by weight.

[0027]

(2) 0.25 <D / t <3 (1) 0.3 <D / t <2 (2)

Here, D is the average particle diameter (μm) of the filler particles contained in the coating layer, and t is the thickness (μm) of the coating layer.

When the value of the above formula (1) is less than 0.25, the blocking resistance, particularly the blocking resistance during wet heat and dew condensation, becomes poor. If it exceeds, the medium layer due to particle falling off in the later process,
This is not desirable because it causes troubles of the printing layer. On the other hand, when the amount of the filler particles exceeds 20% by weight, the strength of the coating layer is reduced, and troubles such as coating film scraping occur in the subsequent steps, which is not desirable.

Examples of filler particles include inorganic fillers such as silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin, talc, titanium oxide, zinc oxide, barium sulfate, etc .; An organic filler made of a heat-resistant resin such as a polystyrene resin, a crosslinked acrylic resin, a urea resin, a melamine resin, and the like can be given. Among these, silicon oxide, aluminum oxide, crosslinked polystyrene resin particles, and crosslinked acrylic resin particles are particularly preferable.

In the present invention, the film-forming coating agent is applied to at least one surface of the polyester film. The film at the time of application is preferably a polyester film before the crystal orientation is completed. In this case, after the application, the film is subjected to a stretching treatment for completing the crystal orientation and further to a heat setting treatment.

As the polyester film before the completion of the crystal orientation, an unstretched film obtained by heat-melting the polyester into a film and a uniaxial film obtained by stretching the unstretched film in either the machine direction or the transverse direction are used. Examples of the stretched film include those stretched at a low magnification in two directions of a longitudinal direction and a transverse direction (a biaxially stretched film before being finally stretched in a longitudinal direction or a transverse direction to complete orientation crystallization). be able to.

As a method of applying the coating agent to the polyester film, any coating method can be applied. For example, a roll coating method, a gravure coating method, a microgravure coating method, a reverse coating method, a roll brush method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like may be applied alone or in combination.

The coating agent in the present invention is preferably an aqueous coating agent, but may be an organic solvent. The aqueous coating composition may contain a small amount of an organic solvent for the purpose of assisting the stability of the coating composition or the coatability of the coating composition. Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, methanol, ethanol, n-propanol, isopropanol, and the like. These can be used alone or in combination of two or more.

The coating composition of the present invention, particularly the aqueous liquid, may be combined with another surfactant in order to improve the wettability to the aromatic polyester film as long as the object of the present invention is not impaired. The surface tension of the coating is 50dy
Ne / cm or less, preferably 40 dyne / cm or less is preferable. The solid content concentration of the coating composition in the present invention is usually 0.5 to 3
It is preferably 0% by weight.

In addition, other additives such as an ultraviolet absorber, a pigment, a lubricant, an anti-blocking agent, a cross-linking agent such as melamine, epoxy and aziridine, and an antistatic agent may be mixed within a range not to impair the object of the present invention. Can be.

The coating amount is preferably 3 to 50 g, more preferably 5 to 40 g per m ² of the running film. The thickness of the final dried coating film (coating) needs to be 0.05 to 0.3 μm, and preferably 0.07 to 0.2 μm. When the thickness of the coating film is less than 0.05 μm, the adhesiveness becomes insufficient, and when it exceeds 0.3 μm, blocking easily occurs.

The coating can be performed on only one side or both sides depending on the use of the film. After coating, the coating is dried to form a uniform coating.

In the present invention, after the coating agent is applied to the polyester film, drying, preferably stretching treatment is performed. This drying is preferably performed at 90 to 130 ° C. for 2 to 20 seconds. This drying can also serve as a pre-heat treatment for the stretching treatment or a heat treatment for the stretching.

The thus-obtained coated film adheres well to the release layer (medium layer) of an in-mold transfer foil which is usually formed by applying and drying a solution of a melamine resin or the like, and is highly practical. Become.

[0041]

EXAMPLES The present invention will be further described below with reference to examples. The characteristics in the examples were obtained by the following method.

1. Particle size (D, unit: μm) A 200 ppm aqueous liquid of particles was used as a sample, and a fine particle analyzer Nicomp Model 270 (Pac
of the equivalent spherical diameters of all the particles determined by the light scattering method using the optical scattering method (manufactured by S.I.S. Scientific) at 50% by weight.

2. dF10 / dS (unit: Kg / mm2 /
The film is sampled to a width of 10 mm and a length of 150 mm, and is pulled by a well-known tensile tester at a distance of 100 mm between chucks and at a speed of 100 mm / min. A tangent gradient at a position corresponding to 10% elongation of the obtained stress-elongation curve is determined.

3. Practical characteristics of the film a) Evaluation of adhesive strength A methyl ethyl ketone / toluene solution of a melamine resin is applied on the coating surface of the film to form a release layer film having a thickness of 1 μm, and the laminate is put on a blank by hot pressing. Observe the condition of the release layer when molded. A: No change B: Partially peeled C: Totally peeled ····· A satisfies practical performance.

B) Evaluation of solvent resistance A gauze immersed in a mixed solution of methyl ethyl ketone / toluene is superimposed on the coated surface of the film, and rubbed while applying a load of 0.2 kg to observe the condition of the coated surface. A: No change B: Partly missing C: Overall missing ··· A satisfies practical performance.

C) Evaluation of anti-blocking property A film obtained by laminating films and applying a tension of 0.3 kg / mm 2 and wrapping the core around a metal core is immersed in water, taken out and aged at 50 ° C. for 17 hours. The film removed from the core is subjected to a T-peel test using a tensile tester, and the peel force is measured. A: Spontaneous peeling when removed from core B: Peeling force is less than 5 g / cm width C: Peeling force is 5 g / cm width or more D: Completely blocking, and film breaks upon peeling Up to B satisfies practical performance, and A is particularly preferred.

D) Evaluation of Formability A film of a release layer is formed on the coating surface of the film in the same manner as in a), and the condition of the base film when molded on a mold is observed. A: Formed with uniform thickness without film breakage, crack generation, etc. B: Does not break, but there is a locally extremely thin portion of the film C: Film breaks ... from A to B Satisfy the practical performance, and A is particularly preferable.

E) Light transmittance (transparency) Measured by a HR-100 haze maker manufactured by Murakami Color Research Laboratory according to ASTM D1003. A: 87% or more B: less than 87% to 85% or more C: less than 85% ... A to B satisfy practical performance, and A is particularly preferable.

Example 1 Polyethylene terephthalate (intrinsic viscosity: 0.64) was melt-extruded on a rotary cooling drum maintained at 20 ° C. to form an unstretched film, and the unstretched film was 3.4 times in the machine axis direction. Stretching and then an intrinsic viscosity of 0.53 made from propylene oxide adduct of terephthalic acid, isophthalic acid, 5-Na sulfoisophthalic acid, ethylene glycol and bisphenol A
80% by weight of an aqueous dispersion A having a solid content of 10% and an average particle diameter of 65 nm using a copolymerized polyester (Tg = 79 ° C.), and an aqueous dispersion of silica particles (average particle diameter of 90 nm) (concentration: 10% by weight) 10% by weight and an aqueous solution of polyoxyethylene nonylphenyl ether as a surfactant (concentration: 1)
(0% by weight) A primer coating solution consisting of 10% by weight was applied to one surface of the film by a kiss coat method. Subsequently, the film was stretched 3.5 times in the transverse direction while drying, and further heat-set at 215 ° C. to obtain a biaxially stretched polyester film (thickness: 35 μm) having a coating film having a thickness of 0.20 μm.

The properties of this film are shown in Tables 2 and 3. As is apparent from Table 3, the film of Example 1 satisfied all the required characteristics.

Example 2 and Comparative Examples 1-2 The same procedure as in Example 1 was carried out except that the aqueous dispersions B to D shown in Table 1 were used instead of the aqueous dispersion A, to obtain a coating having a thickness of 0.20 μm. A biaxially stretched polyester film having a film (thickness: 35 μm) was obtained. Tables 2 and 3 show the properties of these films. Table 3
As is clear, the film of Example 2 satisfied all the required characteristics. On the other hand, the films of Comparative Examples 1 and 2, which did not satisfy the requirement of the secondary transition point in the present invention, did not satisfy the blocking resistance and the light transmittance, as is clear from Table 3.

Example 3 and Comparative Examples 3 and 4 A biaxially stretched polyester film (35 μm thick) was prepared in the same manner as in Example 1 except that the thickness of the coating film was changed as shown in Table 2.
I got Tables 2 and 3 show the properties of these films.
As is clear from Table 3, the film of Example 3 satisfied all the required characteristics. On the other hand, the films of Comparative Examples 3 and 4, which did not satisfy the requirements for the thickness of the coating film in the present invention, did not satisfy the adhesiveness and the blocking resistance as is clear from Table 3.

[Examples 4 and 5] A biaxially stretched polyester film having a coating thickness of 0.20 μm in the same manner as in Example 1 except that the particle size of the added silica particles was changed as shown in Table 2. (Thickness: 35 μm). Tables 2 and 3 show the properties of these films. As is clear from Table 3, the films of Examples 4 and 5 satisfied all the required characteristics.

Example 6 and Comparative Example 5 The procedure of Example 1 was repeated, except that aqueous dispersions E to F having the average particle diameters shown in Table 1 were used instead of aqueous dispersion A. Biaxially stretched polyester film having a coating thickness of 20 μm (thickness 35
μm). Tables 2 and 3 show the properties of these films. As is apparent from Table 3, the film of Example 6 satisfied all the required characteristics. On the other hand, the film of Comparative Example 5 which did not satisfy the requirement of the average particle size in the present invention did not satisfy the light transmittance as is clear from Table 3.

[Comparative Example 6] In Comparative Example 6, a coating film having a thickness of 0.20 µm was formed in the same manner as in Example 1 except that the stretching ratios in the longitudinal and transverse directions were set to 4.1 times and 4.4 times. A biaxially stretched polyester film having a thickness of 35 μm was obtained. Tables 2 and 3 show the properties of these films. The film of Comparative Example 6 which does not satisfy the requirements of the film of the present invention is shown in Table 3.
As is clear, the moldability was not satisfied.

Comparative Example 7 Tables 2 and 3 show the properties of the biaxially oriented polyester film (thickness: 35 μm) obtained in Example 1 without primer coating. As is clear from Table 3, since no coating film was applied, the adhesiveness was poor.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

[Table 3]

[0060]

According to the transfer foil film of the present invention, when a release layer is provided on a coating layer and a printing layer is further coated thereon, the transparency of the film is high, so that It can be easily observed, and when used as a laminated film for in-mold molding transfer, the adhesiveness between the coating layer and the release layer is high, and the interface between the coating layer and the release layer may peel during molding. Since there is no printing layer, the printing layer can be uniformly transferred to the product side. Further, since the transfer foil film of the present invention is excellent in moldability, troubles such as poor molding and poor transfer due to breakage of the film during molding can be prevented. Furthermore, the coating layer of the transfer foil film of the present invention has blocking resistance,
Since it has excellent solvent resistance, it is excellent in workability when applying a release layer on a transfer foil film, and even when a solvent-based coating solution is used when applying a release layer, Thereby, the adhesive strength between the release layer and the base film does not decrease.

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 B29C 45/14-45/16 C08J 7/04

Claims (4)

(57) [Claims] 1. A dicarboxylic acid component having a metal base dispersed in a coating material as fine particles having an average particle diameter of 100 to 20 nm on at least one surface of a polyester film in an amount of 2 to 8 m.
ol%, a coating having a secondary transition point of 40 to 85 ° C. and a coating layer having a dry coating thickness of 0.05 to 0.3 μm is applied using a coating material having a main solid component of a copolymerized polyester,
And dF10 / dS of the film is 0.10 to 0.30K
g / mm ² /% of elongation%. 2. The transfer foil film according to claim 1, wherein the coating layer contains 0.1 to 20% by weight of filler particles satisfying the following formula (1). [Formula 1] 0.25 <D / t <3 (1) [where D is the average particle diameter (μm) of the filler particles contained in the coating layer, and t is the thickness (μm) of the coating layer. ). ] 3. The transfer foil film according to claim 1, wherein the metal base of the dicarboxylic acid component constituting the copolymerized polyester is an alkali metal base sulfonate. 4. The film for a transfer foil according to claim 1, wherein the light transmittance of the film is 85% or more.