Heat Transfer Foil

Abstract

Provided is a thermal transfer foil that can ensure the solvent resistance and abrasion resistance of a transfer layer attached to an object. The thermal transfer foil 100 includes a substrate 4 and a transfer layer 10 disposed on the substrate 4. The transfer layer 10 includes a release layer 1, a color layer 2, and an adhesive layer 3, which are laminated in order from the substrate 4 to the substrate. The release layer 1 contains an isocyanate compound (A) and a polyol compound (B). The isocyanate compound (A) contains a first isocyanate compound (A1) and a second isocyanate compound (A2) that are different from each other. The first isocyanate compound (A1) does not have an isocyanate group blocked with a blocking agent. The second isocyanate compound (A2) has an isocyanate group blocked with a blocking agent.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to heat transfer foils, and more particularly to heat transfer foils used to decorate objects. [Background technology]

[0002] Patent Document 1 relates to a transfer foil that is used by adhering it closely to the outer surface of a rod-shaped object having a first outer surface and a second outer surface with different taper angles, and discloses that the transfer foil has a base sheet and a transfer layer laminated on the base sheet, the transfer layer having a release layer for surface protection, an ink layer for forming a pattern, an adhesive layer, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-163861 A Summary of the Invention

[0004] An object of the present disclosure is to provide a thermal transfer foil that can ensure the solvent resistance and abrasion resistance of a transfer layer attached to an object.

[0005] A thermal transfer foil according to one embodiment of the present disclosure includes a substrate and a transfer layer disposed on the substrate. The transfer layer includes a release layer, a color layer, and an adhesive layer, which are laminated in order from the substrate to the substrate. The release layer includes an isocyanate compound (A) and a polyol compound (B) having thermoplasticity. The isocyanate compound (A) includes a first isocyanate compound (A1) and a second isocyanate compound (A2) which are different from each other. The first isocyanate compound (A1) does not have an isocyanate group blocked with a blocking agent. The second isocyanate compound (A2) has an isocyanate group blocked with a blocking agent. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic cross-sectional view of a thermal transfer foil in one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing a process for transferring a thermal transfer foil in one embodiment of the present disclosure. [Diagram 3] FIG. 3 is a schematic cross-sectional view following FIG. 2, showing a process for transferring a thermal transfer foil in one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] [Embodiment] Hereinafter, embodiments of the present disclosure will be described. Note that the present disclosure is not limited to the following embodiments. The following embodiments are merely examples of various embodiments of the present disclosure, and various modifications are possible depending on the design as long as the object of the present disclosure can be achieved. In addition, the scope of the present disclosure is not limited by the development history described below. Furthermore, the mechanism of action described in the following description is speculated, and the present disclosure is not bound by the mechanism of action described below.

[0008] (overview) First, the background to the present disclosure will be described.

[0009] Conventionally, the outer surface of a shaft or the like has often been decorated to enhance the distinctiveness and added value of the product.

[0010] As a method of applying this decoration, in addition to providing a pattern by painting or printing, a method of attaching decoration using thermal transfer foil has also been proposed (Patent Document 1). Thermal transfer foil has the advantage of allowing a high degree of freedom in decoration and being easy to handle. In particular, shafts are required to have designs consisting of various patterns and colors as well as characters such as product logos, so decoration using thermal transfer foil is preferably used.

[0011] Conventional thermal transfer foils are provided with a transfer film composed of a plurality of layers such as a release layer, an ink layer, and an adhesive layer, and decoration is performed by attaching the transfer film to a shaft or the like. Usually, a shaft or the like with a transfer film attached is often exposed to a harsh environment. Therefore, an overcoat may be applied to protect the transfer film. However, there has been a problem that the process of applying the overcoat requires labor and cost.

[0012] In response to the above problems, as a result of intensive research and development, the inventor has developed a thermal transfer foil 100 that can ensure the solvent resistance and abrasion resistance of the transfer layer 10 attached to the object 20.

[0013] The thermal transfer foil 100 according to the present embodiment includes a base material 4 and a transfer layer 10 disposed on the base material 4. The transfer layer 10 includes a release layer 1, a color layer 2, and an adhesive layer 3 laminated in this order from the closest to the base material 4 (see FIG. 1). The release layer 1 contains an isocyanate compound (A) and a polyol compound (B) having thermoplasticity. The isocyanate compound (A) contains a first isocyanate compound (A1) and a second isocyanate compound (A2) that are different from each other. The first isocyanate compound (A1) does not have an isocyanate group blocked by a blocking agent. The second isocyanate compound (A2) has an isocyanate group blocked by a blocking agent.

[0014] Although the reason for achieving the above effect when the thermal transfer foil 100 has the above configuration is not necessarily clear, it can be speculated as follows.

[0015] The release layer 1 contains the first isocyanate compound (A1). Therefore, by attaching the transfer layer 10 to the object 20 while heating, the first isocyanate compound (A1) contained in the release layer 1 can be reacted with the polyol compound (B). As a result, the abrasion resistance of the release layer 1 can be enhanced.

[0016] Then, by further heating the transfer layer 10 after attaching it to the object 20, the blocking agent contained in the second isocyanate compound (A2) can be efficiently removed. In this case, the reaction between the second isocyanate compound (A2) and the polyol compound (B) can be efficiently promoted. Therefore, the curing of the release layer 1 can be further promoted. This allows the abrasion resistance of the release layer 1 to be further improved while also increasing the solvent resistance.

[0017] By this mechanism, the thermal transfer foil 100 can ensure the solvent resistance and abrasion resistance of the transfer layer 10 attached to the object 20.

[0018] (Transfer layer) The layers included in the transfer layer 10 will be described.

[0019] <Release layer> As described above, the transfer layer 10 includes the release layer 1. The release layer 1 overlaps the substrate 4. The thickness of the release layer 1 is, for example, 2 μm or more and 6 μm or less. In this case, the solvent resistance and abrasion resistance of the release layer 1 can be sufficiently ensured. This thickness is preferably 3 μm or more. This thickness is preferably 5 μm or less.

[0020] The release layer 1 contains an isocyanate compound (A) and a polyol compound (B). This allows the release layer 1 to harden. The isocyanate compound (A) contains two types of isocyanate compounds, a first isocyanate compound (A1) and a second isocyanate compound (A2). This allows the solvent resistance and abrasion resistance of the release layer 1 to be improved. As a result, the solvent resistance and abrasion resistance of the transfer layer 10 attached to the object 20 can be ensured.

[0021] The content of the isocyanate compound (A) relative to the polyol compound (B) is preferably 10% by mass or more and 30% by mass or less. In this case, the solvent resistance and abrasion resistance of the release layer 1 can be further improved. This content is more preferably 15% by mass or more. This content is further preferably 25% by mass or less.

[0022] <Primary isocyanate compound> As described above, the isocyanate compound (A) contains the first isocyanate compound (A1). The first isocyanate compound (A1) does not have an isocyanate group blocked with a blocking agent. In this case, the isocyanate group of the first isocyanate compound (A1) and the hydroxyl group of the polyol compound (B) can easily react with each other. Therefore, when the transfer layer 10 is attached to the object 20 while being heated, the first isocyanate compound (A1) contained in the release layer 1 can react with the polyol compound (B). This can increase the abrasion resistance of the release layer 1. The heating performed when attaching the transfer layer 10 to the object 20 here is, for example, in the range of 190°C or more and 230°C or less. In addition, since the time required to attach the transfer layer 10 to the object 20 is relatively short, the blocking agent of the second isocyanate compound (A2) is difficult to be removed at this point.

[0023] The molecular form that the first isocyanate compound (A1) can take is not particularly limited. For example, the first isocyanate compound (A1) contains at least one selected from the group consisting of a monomer, an oligomer, a prepolymer, a polymer, and the like.

[0024] As described above, the first isocyanate compound (A1) may contain a monomer. The number of isocyanate groups contained in one molecule of the monomer contained in the first isocyanate compound (A1) is not particularly limited, but is preferably 2. In other words, the first isocyanate compound (A1) preferably contains a bifunctional isocyanate monomer. In this case, the abrasion resistance of the release layer 1 can be further improved. Furthermore, the bifunctional isocyanate monomer contains at least one selected from the group consisting of an aliphatic diisocyanate monomer, an alicyclic diisocyanate monomer, and an aromatic diisocyanate monomer. The bifunctional isocyanate monomer preferably contains at least one of an aliphatic diisocyanate monomer and an alicyclic diisocyanate monomer. In this case, the abrasion resistance of the release layer 1 can be further improved.

[0025] The aliphatic diisocyanate monomer contains at least one selected from the group consisting of, for example, butane diisocyanate, pentane diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, etc. The alicyclic diisocyanate monomer contains at least one selected from the group consisting of, for example, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,4-cyclohexane diisocyanate, etc. Furthermore, the aromatic diisocyanate monomer contains at least one selected from the group consisting of, for example, phenylene 1,4-diisocyanate, tolylene 2,4-diisocyanate, tolylene 2,6-diisocyanate, naphthylene 1,5-diisocyanate, diphenylmethane 2,2'-diisocyanate, diphenylmethane 2,4'-diisocyanate, and diphenylmethane 4,4'-diisocyanate. Among these, it is particularly preferable that the first isocyanate compound (A1) contains at least one of hexamethylene diisocyanate and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate). In this case, the abrasion resistance of the release layer 1 can be particularly improved.

[0026] As described above, the first isocyanate compound (A1) may contain at least one of an oligomer, a prepolymer, and a polymer. In other words, the first isocyanate compound (A1) may contain a polyisocyanate resin. In this case, the abrasion resistance of the release layer 1 can be further improved. The polyisocyanate resin is a compound having two or more isocyanate groups in one molecule. The number of isocyanate groups that the polyisocyanate resin has in one molecule is not particularly limited, and the number can be adjusted appropriately. This allows the curing property of the release layer 1 to be adjusted. In addition, the polyisocyanate resin may have an isocyanate group at the molecular end, or may have an isocyanate group inside the molecule.

[0027] It is preferable that the first isocyanate compound (A1) contains both a monomer and a polyisocyanate resin. In this case, it is possible to further improve the abrasion resistance of the release layer 1. It is particularly preferable that the first isocyanate compound (A1) contains hexamethylene diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, and a polyisocyanate resin.

[0028] The content of the first isocyanate compound (A1) relative to the isocyanate compound (A) is preferably 10% by mass or more and 30% by mass or less. If this content is 15% by mass or more, the abrasion resistance of the release layer 1 can be further improved. If this content is 25% by mass or less, the transferability of the thermal transfer foil 100 can be ensured.

[0029] In addition, when the release layer 1 does not contain the first isocyanate compound (A1) but contains only the second isocyanate compound (A2) as the isocyanate compound (A), the second isocyanate compound (A2) contained in the release layer 1 tends to seep out from the release layer 1 and come into contact with the color layer 2 or the adhesive layer 3. In contrast, the isocyanate compound (A) in the present disclosure contains the first isocyanate compound (A1) in addition to the second isocyanate compound (A2). Therefore, the abrasion resistance of the release layer 1 can be sufficiently ensured, and the seepage of the first isocyanate compound (A1) from the release layer 1 can be reduced.

[0030] In addition, when the surface of the substrate 4 overlapping with the release layer 1 has irregularities, for example, when the substrate 4 is a matte surface, when the substrate 4 is peeled off from the release layer 1 (see FIG. 3), the irregularities of the substrate 4 are transferred to the release layer 1, and the surface of the release layer 1 may have irregularities. However, if the release layer 1 does not contain the first isocyanate compound (A1) but contains only the second isocyanate compound (A2) as the isocyanate compound (A), when the transfer layer 10 is transferred to the target object 20 by pressing the heated transfer roll 6 against the substrate 4 (see FIG. 2), the surface of the substrate 4 is likely to become smooth with the heat curing of the second isocyanate compound (A2). As a result, the irregularities on the surface of the substrate 4 are not easily transferred to the release layer 1. In contrast, the isocyanate compound (A) in the present disclosure contains the first isocyanate compound (A1) in addition to the second isocyanate compound (A2). This increases the coating strength of the release layer 1, so that the unevenness of the surface of the base material 4 is maintained even after the second isocyanate compound (A2) is cured by heating, and the unevenness of the base material 4 can be transferred to the release layer 1.

[0031] <Secondary isocyanate compounds> As described above, the isocyanate compound (A) contains the second isocyanate compound (A2). At least a part of the isocyanate groups of the second isocyanate compound (A2) is blocked with a blocking agent. That is, the second isocyanate compound (A2) is a blocked isocyanate compound.

[0032] As described above, when the second isocyanate compound (A2) is heated, the blocking agent can be efficiently released. In this case, the transfer layer 10 can be heated after being attached to the object 20 to promote hardening of the release layer 1. This can increase the abrasion resistance of the release layer 1.

[0033] More specifically, by applying heat to the release layer 1, the abrasion resistance of which has been increased by attaching the transfer layer 10 to the object 20 while heating it, the reaction between the second isocyanate compound (A2) and the polyol compound (B) proceeds, and the hardening of the release layer 1 proceeds, thereby further increasing the abrasion resistance of the release layer 1. Note that the heating performed after attaching the transfer layer 10 to the object 20 referred to here may be performed at a temperature in the range of 80°C or higher and 150°C or lower, for example.

[0034] The second isocyanate compound (A2) may have isocyanate groups that are not blocked by a blocking agent, as long as at least a part of the isocyanate groups is blocked by a blocking agent. The blocking agent contains at least one selected from the group consisting of active methylene-based blocking agents, oxime-based blocking agents, alcohol-based blocking agents, acid amide-based blocking agents, acid imide-based blocking agents, phenol-based blocking agents, amine-based blocking agents, imidazole-based blocking agents, and pyrazole-based blocking agents. These blocking agents may be used alone or in combination of two or more.

[0035] In addition, by appropriately selecting the blocking agent, the temperature at which the blocking agent is desorbed from the second isocyanate compound (A2) can be adjusted. This allows the temperature at which the release layer 1 is cured to be adjusted. The temperature at which the blocking agent is desorbed from the second isocyanate compound (A2) is preferably 80°C or higher and 120°C or lower. By setting the temperature at which the blocking agent is desorbed to 80°C or higher, the release layer 1 can be prevented from being excessively cured until the transfer layer 10 is attached to the object 20. This allows the transferability of the thermal transfer foil 100 to be sufficiently ensured. Furthermore, by setting the temperature at which the blocking agent is desorbed to 120°C or lower, the release layer 1 can be heated and cured at a temperature that does not impair the quality of the object 20. The temperature at which the blocking agent is desorbed is preferably 110°C or lower, more preferably 100°C or lower, and even more preferably 90°C or lower. The temperature at which the blocking agent possessed by the second isocyanate compound (A2) is desorbed can be confirmed as follows. First, a mixture of the polyol compound (B) and the second isocyanate compound (A2) is applied to a substrate (such as a sample-coated plate) and heated at a temperature in the range of 90°C to 120°C for 60 minutes to form a coating film. The formed coating film is then cooled to room temperature. A rubbing test is then performed on the surface of the coating film with a cotton swab soaked in methyl ethyl ketone, with a load of 150 g. The rubbing test is repeated by rubbing the cotton swab back and forth over a distance of 20 mm, until the number of rubbings reaches 50 or the coating film dissolves and the surface of the substrate is exposed. If the surface of the substrate is not exposed even after rubbing 50 times or more, it is determined that the blocking agent has been removed and the curing has progressed completely. In this case, the heating temperature after applying the mixture is reduced by 1°C, a coating film is formed again, and the above rubbing test is repeated again. On the other hand, if the number of rubbings is less than 50 times and the surface of the substrate is exposed, it is determined that the removal of the blocking agent has not progressed sufficiently and the curing has not progressed. In this case, the heating temperature after coating the mixture is increased by 1°C, a coating film is formed again, and the above rubbing test is repeated.According to the above-mentioned method, when the mixture was heated to form a coating film, the lowest heating temperature at which the surface of the substrate was not exposed even when rubbed 50 times or more with a cotton swab dipped in methyl ethyl ketone was determined as the temperature at which the blocking agent contained in the second isocyanate compound (A2) was released.

[0036] In addition, the molecular form that the second isocyanate compound (A2) can take is not particularly limited. For example, the second isocyanate compound (A2) contains at least one selected from the group consisting of a monomer, an oligomer, a prepolymer, a polymer, and the like. Among these, the second isocyanate compound (A2) preferably contains at least one of a prepolymer and a polymer. In other words, the second isocyanate compound (A2) preferably contains a blocked polyisocyanate resin. In this case, the abrasion resistance and solvent resistance of the release layer 1 can be further improved. The blocked polyisocyanate resin is a compound having two or more isocyanate groups in one molecule, at least one of which is blocked with a blocking agent.

[0037] The content of the second isocyanate compound (A2) relative to the isocyanate compound (A) is preferably 70% by mass or more and 90% by mass or less. In this case, the abrasion resistance and solvent resistance of the release layer 1 can be further improved. This content is more preferably 75% by mass or more. This content is more preferably 85% by mass or less.

[0038] <Polyol compound> As described above, the release layer 1 contains the polyol compound (B). As described above, in the release layer 1, the first isocyanate compound (A1) and the polyol compound (B) can be reacted by attaching the transfer layer 10 to the object 20 while heating the transfer layer 10. At the stage when the transfer layer 10 is attached to the object 20, the first isocyanate compound (A1) may be partially or entirely reacted with the polyol compound (B).

[0039] The polyol compound (B) has thermoplasticity. In other words, the polyol compound (B) is a thermoplastic resin having a hydroxyl group. For example, the polyol compound (B) contains at least one selected from the group consisting of polyester polyols, acrylic polyols, polyether polyols, polyolefin polyols, fluorine polyols, polycarbonate polyols, and vinyl chloride-vinyl acetate copolymer polyols. Furthermore, it is particularly preferable that the polyol compound (B) contains a vinyl chloride-vinyl acetate copolymer polyol (vinyl chloride-vinyl acetate polyol), and in this case, the solvent resistance and abrasion resistance of the release layer 1 can be particularly improved.

[0040] In this disclosure, vinyl chloride-vinyl acetate copolymer polyol means a vinyl chloride-vinyl acetate copolymer having two or more hydroxyl groups in one molecule. There is no particular limitation on the method for producing vinyl chloride-vinyl acetate polyol, but for example, vinyl chloride-vinyl acetate polyol can be produced by chemically modifying a part of vinyl chloride-vinyl acetate copolymer to give a hydroxyl group. Also, vinyl chloride-vinyl acetate polyol can be produced by saponifying vinyl chloride-vinyl acetate copolymer to eliminate acetyl groups from the part derived from vinyl acetate and generate hydroxyl groups.

[0041] The content of the polyol compound (B) in the entire release layer 1 is preferably 55% by mass or more and 65% by mass or less. In this case, the solvent resistance and abrasion resistance of the release layer 1 can be further improved. This content is more preferably 60% by mass or more. This content may be 70% by mass or less.

[0042] The mass ratio of the isocyanate compound (A) to the polyol compound (B) is preferably 10:90 to 30:70. In this case, the solvent resistance and abrasion resistance of the release layer 1 can be improved. This mass ratio is more preferably 15:85 to 25:75.

[0043] <Solvent> In preparing the release layer 1, a solvent (C) may be used. Therefore, the solvent (C) may remain in the release layer 1. The solvent (C) is not particularly limited as long as it is used as a solvent for paints, and contains at least one selected from the group consisting of ester compounds, ether compounds, ketone compounds, hydrocarbon compounds, and glycol ether compounds. The hydrocarbon-based compound contains at least one of an aliphatic hydrocarbon compound and an aromatic hydrocarbon compound. The solvent (C) preferably contains at least one of a ketone compound and an aromatic hydrocarbon compound, and more specifically, it preferably contains at least one of isophorone, Solvesso 150, and cyclohexanone.

[0044] The content of the solvent in the entire peeling layer 1 is preferably 15% by mass or less, in which case the transferability and printability of the thermal transfer foil 100 can be sufficiently ensured.

[0045] Additives The release layer 1 contains, for example, an additive (D) in addition to an isocyanate compound (A), a polyol compound (B) and a solvent (C). Examples of the additive (D) include a defoaming agent and a leveling agent. The defoaming agent contains, for example, a silicone resin. The leveling agent contains, for example, a silicone resin.

[0046] <Color layer> As described above, the transfer layer 10 includes the color layer 2. The color layer 2 is laminated on the release layer 1. The color layer 2 may include a plurality of layers. The thickness of each layer included in the color layer 2 is 2 μm or more and 6 μm or less. In this case, the solvent resistance and abrasion resistance of the color layer 2 can be sufficiently ensured.

[0047] For example, the color layer 2 contains an isocyanate compound (E) and a polyol compound (F). In this case, the abrasion resistance and solvent resistance of the color layer 2 can be improved.

[0048] It is preferable that the isocyanate compound (E) does not contain an isocyanate compound (E1) that does not have an isocyanate group blocked with a blocking agent. In this case, the color layer 2 can be formed on the release layer 1 without curing. This makes it possible to prevent the transferability of the thermal transfer foil 100 from being impaired.

[0049] In addition, the isocyanate compound (E) preferably contains an isocyanate compound (E2) having an isocyanate group blocked with a blocking agent. In this case, the color layer 2 can be cured by heating the transfer layer 10 after the transfer layer 10 is attached to the object 20. Therefore, the solvent resistance and abrasion resistance of the color layer 2 can be improved while the transferability of the thermal transfer foil 100 is sufficiently ensured.

[0050] The isocyanate compound (E) contained in the color layer 2 is not particularly limited, but for example, a compound similar to the isocyanate compound (A) contained in the release layer 1 can be used.

[0051] The polyol compound (F) contained in the color layer 2 is not particularly limited, but may be the same as the polyol compound (B) contained in the release layer 1. The color layer 2 preferably contains a vinyl chloride-vinyl acetate polyol as the polyol compound (F). In this case, the solvent resistance and abrasion resistance of the color layer 2 can be improved.

[0052] Furthermore, in addition to the isocyanate compound (E) and the polyol compound (F), the color layer 2 may contain at least one selected from the group consisting of an antifoaming agent, a thickener, a solvent, and the like. The solvent contained in the color layer 2 may be the same compound as the solvent (C) that the release layer 1 may contain. The antifoaming agent contained in the color layer 2 may be the same compound as the antifoaming agent contained in the release layer 1. The color layer 2 may be the same compound as the thickener that the release layer 1 may contain.

[0053] <Adhesive layer> As described above, the transfer layer 10 includes the adhesive layer 3. The adhesive layer 3 is laminated on the color layer 2. The thickness of the adhesive layer 3 is 2 μm or more and 6 μm or less. In this case, the solvent resistance and abrasion resistance of the adhesive layer 3 can be sufficiently ensured.

[0054] For example, the adhesive layer 3 contains an isocyanate compound (G) and a polyol compound (H). In this case, the abrasion resistance and solvent resistance of the adhesive layer 3 can be improved.

[0055] It is preferable that the isocyanate compound (G) does not contain an isocyanate compound (G1) that does not have an isocyanate group blocked with a blocking agent. In this case, the adhesive layer 3 can be formed on the color layer 2 without curing. This can further ensure the adhesion between the adhesive layer 3 and the object 20.

[0056] In addition, the isocyanate compound (G) preferably contains an isocyanate compound (G2) having an isocyanate group blocked with a blocking agent. In this case, the adhesive layer 3 can be cured by heating the transfer layer 10 after the transfer layer 10 is attached to the object 20. Therefore, the adhesive layer 3 can be improved in solvent resistance and abrasion resistance while ensuring the adhesiveness between the adhesive layer 3 and the object 20.

[0057] The isocyanate compound (G) contained in the adhesive layer 3 is not particularly limited, but for example, a compound similar to the isocyanate compound (A) contained in the release layer 1 can be used.

[0058] The polyol compound (H) contained in the adhesive layer 3 is not particularly limited, but may be, for example, the same compound as the polyol compound (B) contained in the release layer 1. The adhesive layer 3 preferably contains a vinyl chloride-vinyl acetate polyol as the polyol compound (H). In this case, the solvent resistance and abrasion resistance of the adhesive layer 3 can be improved.

[0059] The adhesive layer 3 may contain at least one selected from the group consisting of an antifoaming agent, a thickener, a solvent, etc., in addition to the isocyanate compound (G) and the polyol compound (H). The solvent contained in the adhesive layer 3 may be the same compound as the solvent (C) that the release layer 1 may contain. The antifoaming agent contained in the adhesive layer 3 may be the same compound as the antifoaming agent contained in the release layer 1. The adhesive layer 3 may be the same compound as the thickener that the release layer 1 may contain.

[0060] (How to make thermal transfer foil) A description will now be given of a method for producing the thermal transfer foil 100. Note that the method for producing the thermal transfer foil 100 is not limited to the following method, and any appropriate method can be adopted depending on the mode of use.

[0061] First, a composition for forming the release layer 1 (hereinafter, composition (L)) is prepared. The composition (L) contains an isocyanate compound (A) and a polyol compound (B), and, if necessary, contains components such as a solvent (C). In addition, a composition for forming the color layer 2 (hereinafter, composition (M)) is prepared. The composition (M) contains components such as an isocyanate compound (E), a polyol compound (F), a solvent, etc. Then, a composition for forming the adhesive layer 3 (hereinafter, composition (N)) is prepared. The composition (N) contains components such as an isocyanate compound (G), a polyol compound (H), a solvent, etc.

[0062] Next, the composition (L) is applied onto the substrate 4 to prepare a coating film, and the coating film is left at room temperature for a while or heated to form the release layer 1. The heating temperature is preferably a temperature at which the isocyanate compound (A) does not react with the polyol compound (B), and is preferably less than 80°C, for example. The method of applying the composition (L) is not particularly limited, and any appropriate method can be applied. Examples of the method of applying the composition (L) include screen printing, reverse roll coating, gravure coating, die coating, roll splash, spray coating, air knife coating, and curtain coating.

[0063] Next, the composition (M) is applied onto the peeling layer 1 to form a coating film, and the coating film is left at room temperature for a while or heated to form the color layer 2. The heating temperature here is preferably a temperature at which the isocyanate compound (A) does not react with the polyol compound (B), or, if the composition (M) contains an isocyanate compound (E), a temperature at which the isocyanate compound (E) does not react with the polyol compound (F), and is preferably, for example, less than 80°C. In this way, the color layer 2 is formed. The method of applying the composition (M) can be the same as the method of applying the composition (L).

[0064] Next, the composition (N) is applied onto the color layer 2 to prepare a coating film, and the coating film is left at room temperature for a while or heated to form the adhesive layer 3. The heating temperature is preferably a temperature at which the isocyanate compound (A) does not react with the polyol compound (B), or, if the composition (M) contains an isocyanate compound (E), a temperature at which the isocyanate compound (E) does not react with the polyol compound (F), or, if the composition (N) contains an isocyanate compound (G), a temperature at which the isocyanate compound (G) does not react with the polyol compound (H), and is preferably, for example, less than 80°C. In this way, the adhesive layer 3 is formed. As a method for applying the composition (N), the same method as the method for applying the composition (L) can be applied.

[0065] (Decoration) A method for decorating an object 20 using the thermal transfer foil 100 will now be described.

[0066] First, the thermal transfer foil 100 is placed on the upper side of the object 20 so that the adhesive layer 3 of the thermal transfer foil 100 faces the object 20. Next, the transfer roll 6 is pressed against the substrate 4 to transfer the transfer layer 10 to the object 20 (see FIG. 2). At this time, the first isocyanate compound (A1) and the polyol compound (B) may mainly react. The temperature of the transfer roll 6 is not particularly limited, but is, for example, 190° C. or higher and 230° C. or lower. This makes it possible to prevent defects from occurring in the transfer layer 10 attached to the object 20. In addition, from the viewpoint of the heat resistance of the substrate 4, it is preferable that the heating time at this time is between 0.2 seconds and 0.3 seconds. Then, after the transfer layer 10 is transferred so as to be in contact with the object 20, the substrate 4 is peeled off from the peeling layer 1 (see FIG. 3). In this way, the transfer layer 10 is attached to the object 20. In addition, in this case, if the color layer 2 does not contain the isocyanate compound (E1), the viscosity of the composition (M) can be suppressed. Therefore, when the composition (M) is applied onto the peeling layer 1 to form the color layer 2, the peeling layer 1 formed earlier can be made difficult to peel off. This can make it possible to prevent defects from occurring in the transfer layer 10. In addition, if the adhesive layer 3 does not contain the isocyanate compound (G1), the viscosity of the composition (N) can be suppressed. Therefore, when the composition (N) is applied onto the color layer 2 to form the adhesive layer 3, the peeling layer 1 formed earlier can be made difficult to peel off. This can make it possible to prevent defects from occurring in the transfer layer 10.

[0067] Next, the object 20 to which the transfer layer 10 is attached is heated to bake the transfer layer 10. The heating method is not particularly limited, but can be performed, for example, by putting the object 20 to which the transfer layer 10 is attached into a heating furnace or the like and heating it in the heating furnace. At this time, mainly the second isocyanate compound (A2) and the polyol compound (B) may react. The heating temperature at this time is, for example, 90°C or higher and 120°C or lower. The heating time is between 30 and 90 minutes, and it is particularly preferable to perform the heating for 90 minutes. If the heating temperature and heating time are within the above ranges, the transfer layer 10 can be sufficiently cured, and as a result, the solvent resistance and abrasion resistance of the transfer layer 10 can be sufficiently ensured.

[0068] By baking the transfer layer 10, the color layer 2 and the adhesive layer 3 can also be cured. In particular, when the color layer 2 contains an isocyanate compound (E2), the isocyanate compound (E2) and the polyol compound (F) can react efficiently. In addition, when the adhesive layer 3 contains an isocyanate compound (G2), the isocyanate compound (G2) and the polyol compound (H) can react efficiently.

[0069] Furthermore, when the heat resistance of the object 20 is low, even if the object 20 is heated at a temperature of 90°C or higher and 120°C or lower, the solvent resistance and abrasion resistance of the transfer layer 10 can be sufficiently ensured, so that deterioration of the quality of the object 20 due to heating can be suppressed.

[0070] According to the above-mentioned method, the thermal transfer foil 100 can be transferred to the object 20. The method of transferring the thermal transfer foil 100 to the object 20 is not limited to the above-mentioned method, and any suitable method and conditions can be adopted depending on the mode of use.

[0071] In addition, when the transfer layer 10 is attached to the object 20, the transfer layer 10 is exposed to the external environment. In the embodiment, since the solvent resistance and abrasion resistance of the transfer layer 10 attached to the object 20 can be ensured, even if the transfer layer 10 is exposed to the external environment, the transfer layer 10 can have good durability. Therefore, the need to protect the transfer layer 10 with an overcoat layer or the like can be reduced, and the process for providing the overcoat layer can be reduced. However, the transfer layer 10 may be covered and protected with an overcoat layer or the like for the purpose of further improving durability. EXAMPLES

[0072] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0073] (composition) <Composition for forming release layer> A composition for forming a release layer (hereinafter referred to as a first composition) was prepared by mixing the components shown in Table 1 in the ratio shown in Table 1. Details of the components are as follows.

[0074] <Unblocked isocyanate compound> · Unblocked isocyanate compound #1: A mixture of hexamethylene diisocyanate and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate) (0.2% by mass of hexamethylene diisocyanate, 0.3% by mass of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate).

[0075] · Unblocked isocyanate compound #2: 0.6% by weight hexamethylene diisocyanate, 85.0% by weight polyisocyanate, 14.4% by weight butyl acetate.

[0076] Unblocked isocyanate compound #3: 75.0% by weight xylylene diisocyanate, 25.0% by weight ethyl acetate.

[0077] · Unblocked isocyanate compound #4: 75.0% by weight of polyisocyanate, 24.5% by weight of ethyl acetate, 0.5% by weight of 2,6-di-tert-butyl-4-methylphenol.

[0078] <Blocked isocyanate compound> Blocked isocyanate compound #1: 70.0 mass % blocked isocyanate compound (blocking agent desorption temperature 110°C), 30.0 mass % propylene glycol monomethyl ether acetate.

[0079] Blocked isocyanate compound #2: 55.0 mass% blocked isocyanate compound (blocking agent desorption temperature 120°C), 45.0 mass% 1-methoxy-2-propanol.

[0080] Blocked isocyanate compound #3: Blocked isocyanate compound (blocking agent desorption temperature 110°C) 69.6 mass%, dipropylene glycol monomethyl ether 30.0 mass%, remaining blocking agent 0.4 mass%.

[0081] Blocked isocyanate compound #4: 70.0 mass% blocked isocyanate compound (blocking agent desorption temperature 110°C), 28.8 mass% 1-methoxy-2-propyl acetate, 1.2 mass% unreacted remaining blocking agent.

[0082] <Polyol compound> · Polyol Compound #1: Chloro-Acetate Polyol.

[0083] <Solvent> Solvent #1: A mixture of cyclohexanone, isophorone and Solvesso 150 (25% by weight cyclohexanone, 25% by weight isophorone, 50% by weight Solvesso 150).

[0084] Additives Additive #1: Defoamer (silicone resin (silicone-based oil)).

[0085] Additive #2: Leveling agent (acrylic polymer).

[0086] <Composition for preparing color layer> A composition for producing a color layer (hereinafter referred to as a second composition) was prepared by mixing the following components.

[0087] Blocked isocyanate compound (blocking agent desorption temperature 110°C). 8% by mass.

[0088] Vinyl chloride / vinyl acetate copolymer polyol. 76% by mass.

[0089] Mixture of cyclohexanone, isophorone and Solvesso 150 (cyclohexanone 25% by mass, isophorone 25% by mass, Solvesso 150 50% by mass). 12% by mass.

[0090] Antifoaming agent (silicone resin (silicone oil)). 2% by mass.

[0091] Thickener (silica). 2% by weight.

[0092] <Composition for forming adhesive layer> A composition for producing an adhesive layer (hereinafter referred to as a third composition) was prepared by mixing the following components.

[0093] Blocked isocyanate compound (blocking agent desorption temperature 110°C). 8% by mass.

[0094] A mixture of vinyl chloride-vinyl acetate copolymer and isocyanate compounds. 75% by mass.

[0095] Mixture of cyclohexanone, isophorone and Solvesso 150 (25% by mass of cyclohexanone, 25% by mass of isophorone, 50% by mass of Solvesso 150). 15% by mass.

[0096] Antifoaming agent (silicone resin (silicone oil)). 2% by mass.

[0097] (Preparation of thermal transfer foil) Thermal transfer foils were prepared from the first composition, the second composition and the third composition according to the following method.

[0098] First, the first composition was applied by screen printing to a release film (a PET film with a release coating of silicone resin on both sides: thickness 25 μm) to prepare a coating film. Then, the coating film was heated by hot air drying to prepare a release layer.

[0099] Next, the second composition was applied onto the release layer by screen printing to prepare a coating film, which was then heated by hot air drying to prepare a color layer.

[0100] Then, the third composition was applied onto the color layer by screen printing to prepare a coating film, which was then heated by hot air drying to prepare an adhesive layer.

[0101] As described above, a thermal transfer foil was produced by laminating a release layer, a color layer, and an adhesive layer in this order on a release film.

[0102] (Evaluation of thermal transfer foil) The transfer layer from the thermal transfer foil was applied to the target (shaft). The silicone roller hardness was 75 to 85°, the silicone roller surface temperature was 190 to 230°C, the shaft rotation speed was 15 to 25 rpm, and the pressure was 15 to 25 kgf / cm. 2 The transfer was performed under the following conditions. The object to which the transfer layer was transferred was then heated at 100° C. for 90 minutes. The object decorated with the transfer layer was evaluated as follows.

[0103] <Solvent resistance test> The area of ​​the object where the transfer layer was attached was rubbed six times with a cloth soaked in a solvent (ethyl acetate), and the state of the transfer layer at that time was evaluated according to the following criteria. The results are shown in Table 1.

[0104] A: No dissolution is observed in the transfer layer B: Dissolution is observed in the transfer layer. <Wear resistance test> The portion of the object where the transfer layer was attached was rubbed continuously with a load of 1250 g at a distance of 150 mm and at an interval of 1 round trip per second, and evaluated according to the following criteria. The results are shown in Table 1.

[0105] A: The surface of the shaft is not exposed even after rubbing it more than 75 times. B: The shaft surface was exposed before 75 rubs. <Check foil cracking properties> The transfer layer attached to the object was visually inspected and evaluated according to the following criteria. The results are shown in Table 1.

[0106] A: No defects are observed in the transfer layer. B: Defects are observed in the transfer layer.

[0107] [Table 1]

[0108] (summary) As is apparent from the above embodiment, the present disclosure includes the following aspects. In the following, reference symbols are given in parentheses only to clarify the correspondence with the embodiment.

[0109] The thermal transfer foil (100) according to the first embodiment of the present disclosure includes a substrate (4) and a transfer layer (10) disposed on the substrate (4). The transfer layer (10) includes a release layer (1), a color layer (2), and an adhesive layer (3) laminated in the order of proximity to the substrate (4). The release layer (1) contains an isocyanate compound (A) and a polyol compound (B) having thermoplasticity. The isocyanate compound (A) contains a first isocyanate compound (A1) and a second isocyanate compound (A2) which are different from each other. The first isocyanate compound (A1) does not have an isocyanate group blocked with a blocking agent. The second isocyanate compound (A2) has an isocyanate group blocked with a blocking agent.

[0110] According to this embodiment, it is possible to provide a thermal transfer foil (100) that can ensure the solvent resistance and abrasion resistance of the transfer layer (10) attached to the object (20).

[0111] The thermal transfer foil (100) according to the second embodiment of the present disclosure is based on the thermal transfer foil (100) according to the first embodiment. The first isocyanate compound (A1) contains at least one of hexamethylene diisocyanate and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate.

[0112] According to this embodiment, the abrasion resistance of the release layer (1) can be further improved.

[0113] A thermal transfer foil (100) according to a third embodiment of the present disclosure is based on the thermal transfer foil (100) according to the first or second embodiment. The first isocyanate compound (A1) contains a polyisocyanate resin.

[0114] According to this embodiment, the abrasion resistance of the release layer (1) can be further improved.

[0115] The thermal transfer foil (100) according to the fourth aspect of the present disclosure is based on the thermal transfer foil (100) according to any one of the first to third aspects. The temperature at which the blocking agent is desorbed from the second isocyanate compound (A2) is 100°C or higher and 120°C or lower.

[0116] According to this embodiment, by setting the temperature at which the blocking agent is desorbed from the first isocyanate compound (A1) to 90° C. or higher, it is possible to prevent the release layer (1) from being excessively cured until the transfer layer (10) is attached to the object (20). This makes it possible to sufficiently ensure the transferability of the thermal transfer foil (100). In addition, by setting the temperature at which the blocking agent is desorbed from the first isocyanate compound (A1) to 120° C. or lower, it is possible to heat and cure the release layer (1) at a temperature that does not impair the quality of the object (20).

[0117] A thermal transfer foil (100) according to a fifth aspect of the present disclosure is based on the thermal transfer foil (100) according to any one of the first to fourth aspects. The color layer (2) contains an isocyanate compound (E) and a polyol compound (F).

[0118] According to this embodiment, the solvent resistance and abrasion resistance of the color layer (2) can be improved.

[0119] The thermal transfer foil (100) according to the sixth embodiment of the present disclosure is based on the thermal transfer foil (100) according to the fifth embodiment. The isocyanate compound (E) does not contain an isocyanate compound (E1) that does not have an isocyanate group blocked with a blocking agent.

[0120] According to this embodiment, the color layer (2) can be formed on the release layer (1) without hardening it, which makes it possible to prevent the transferability of the thermal transfer foil (100) from being impaired.

[0121] A thermal transfer foil (100) according to a seventh aspect of the present disclosure is based on the thermal transfer foil (100) according to the fifth or sixth aspect. The isocyanate compound (E) contains an isocyanate compound (E2) having an isocyanate group blocked with a blocking agent.

[0122] According to this embodiment, the color layer (2) can be cured by heating the transfer layer (10) after the transfer layer (10) is attached to the object (20). Therefore, the solvent resistance and abrasion resistance of the color layer (2) can be improved while the transferability of the thermal transfer foil (100) is sufficiently ensured.

[0123] A thermal transfer foil (100) according to an eighth aspect of the present disclosure is based on the thermal transfer foil (100) according to any one of the first to seventh aspects. The adhesive layer (3) contains an isocyanate compound (G) and a polyol compound (H).

[0124] According to this embodiment, the solvent resistance and abrasion resistance of the adhesive layer (3) can be improved.

[0125] The thermal transfer foil (100) according to the ninth embodiment of the present disclosure is based on the thermal transfer foil (100) according to the eighth embodiment. The isocyanate compound (G) does not contain an isocyanate compound (G1) that does not have an isocyanate group blocked with a blocking agent.

[0126] According to this embodiment, in this case, the adhesive layer (3) can be formed on the release layer (1) without being cured, thereby making it possible to further ensure the adhesion between the adhesive layer (3) and the object (20).

[0127] A thermal transfer foil (100) according to a tenth aspect of the present disclosure is based on the thermal transfer foil (100) according to the eighth or ninth aspect. The isocyanate compound (G) contains an isocyanate compound (G2) having an isocyanate group blocked with a blocking agent.

[0128] According to this embodiment, the adhesive layer (3) can be cured by heating the transfer layer (10) after the transfer layer (10) is attached to the object (20). Therefore, the adhesive layer (3) can be improved in solvent resistance and abrasion resistance while ensuring the adhesion between the adhesive layer (3) and the object (20).

[0129] The thermal transfer foil (100) according to an eleventh aspect of the present disclosure is any one of the first to tenth aspects, wherein the polyol compound (B) contains a vinyl chloride-vinyl acetate copolymer-based polyol. [Explanation of symbols]

[0130] 1. Release layer 2 color layers 3 Adhesive layer 4 Base material 10 Transfer layer 20 Object 100 Heat transfer foil

Claims

1. A substrate and a transfer layer disposed on the substrate, The transfer layer includes a release layer, a color layer, and an adhesive layer, which are laminated in that order from the substrate side, The release layer contains an isocyanate compound (A) and a polyol compound (B) having thermoplasticity, The isocyanate compound (A) contains a first isocyanate compound (A1) and a second isocyanate compound (A2) which are different from each other, The first isocyanate compound (A1) does not have an isocyanate group blocked with a blocking agent, The second isocyanate compound (A2) has an isocyanate group blocked with a blocking agent. Heat transfer foil.

2. The first isocyanate compound (A1) contains at least one of hexamethylene diisocyanate and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate. The thermal transfer foil according to claim 1.

3. The first isocyanate compound (A1) contains a polyisocyanate resin. The thermal transfer foil according to claim 1 or 2.

4. The temperature at which the blocking agent is released from the second isocyanate compound (A2) is 100° C. or higher and 120° C. or lower. The thermal transfer foil according to claim 1.

5. The color layer contains an isocyanate compound (E) and a polyol compound (F). The thermal transfer foil according to claim 1.

6. The isocyanate compound (E) contains an isocyanate compound (E2) having an isocyanate group blocked with a blocking agent. The thermal transfer foil according to claim 5.

7. The adhesive layer contains an isocyanate compound (G) and a polyol compound (H). The thermal transfer foil according to claim 1.

8. The isocyanate compound (G) contains an isocyanate compound (G2) having an isocyanate group blocked with a blocking agent. The thermal transfer foil according to claim 7.

9. The polyol compound (B) contains a vinyl chloride / vinyl acetate copolymer polyol. The thermal transfer foil according to claim 1.

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