Curable resin composition for decorative films and decorative film

Abstract

To provide a curable resin composition for decorative films that offers high flexibility while also yielding a cured product with excellent surface hardness, scratch resistance, and chemical resistance. [Solution] A curable resin composition for decorative films comprising (a) a urethane (meth)acrylate having 2 to 9 unsaturated bonds, and (b) a photopolymerization initiator, wherein the (b) photopolymerization initiator comprises (b-1) a dialkyl peroxide having a thioxanthone skeleton represented by general formula (1), and the (b-1) component is 0.01 to 15 parts by mass per 100 parts by mass of the (a) component.

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition for decorative films and a decorative film. [Background technology]

[0002] Conventionally, methods have been used to apply a hard coat layer to the surface of molded plastics and other materials by coating them with photocurable or thermosetting resins to provide aesthetic appeal, surface hardness, scratch resistance, or chemical resistance for surface protection. However, these methods require molding of the product by injection molding, coating of the resin composition, drying, and curing, resulting in lengthy processes, low productivity, and difficulty in uniformly forming a hard coat layer on molded products with complex shapes.

[0003] On the other hand, recently, molding methods that use decorative films having a printed layer and a hard coat layer to add design elements to the surface of complexly shaped plastic molded products have been attracting attention. A typical molding method using decorative films is film insert molding, in which the decorative film is inserted into the mold during injection molding, and the decorative film and the molded product are molded as one unit. This method is used for molding exterior components with complex shapes in fields such as mobile phones, personal computers, home appliances, and automotive parts. Therefore, the hard coat layer of the decorative film is required to have excellent hard coat properties such as surface hardness, scratch resistance, and chemical resistance (sunscreen resistance, etc.), as well as flexibility to conform to complex shapes.

[0004] Under these circumstances, UV-curable coating compositions have been proposed that can form coating films for decorative films with moldability applicable to molding methods such as film insert molding and in-mold molding. For example, a method for manufacturing injection-molded articles has been proposed that uses a film laminate having a semi-cured resin layer obtained by semi-curing a cationic UV-curable coating composition, and that utilizes a semi-cured film laminate with high surface hardness and excellent adhesion and conformability to resin molded products with three-dimensional curved shapes (Patent Document 1). [Prior art documents]

Patent Document

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the method proposed in Patent Document 1 is difficult to stably produce molded products when molding at high temperatures. In addition, since the semi-cured resin layer is cation-curable, it is necessary to heat for a long time, so it cannot be said that it is a suitable method from the viewpoint of production efficiency. Therefore, it is preferable to use a film laminate in which the cured resin layer is completely cured by ultraviolet curing, but there is a risk that the coating film may crack because it cannot follow a complex shape.

[0007] In general, flexibility and hard coat properties such as surface hardness are mutually contradictory properties. In this regard, although a certain degree of flexibility can be obtained in the conventional curable resin composition, it cannot be said that the hardness, chemical resistance, etc. are still sufficient, and further improvement is required.

[0008] Therefore, an object of the present invention is to provide a curable resin composition for a decorative film that can obtain a cured product having excellent surface hardness, scratch resistance and chemical resistance while having high flexibility.

Means for Solving the Problems

[0009] That is, the present invention is a curable resin composition for a decorative film containing (a) urethane (meth) acrylate having 2 to 9 unsaturated bonds, and (b) a photopolymerization initiator, and the (b) photopolymerization initiator is (b-1) General formula (1):

Chemical formula

[0010] In addition, in the present invention, the (b) photoinitiator further comprises (b-2) a compound represented by the general formula (2): [Chemical formula] (In the general formula (2), R 1 , and R 2 each independently represents a methyl group or an ethyl group, and R 3 is an independent substituent representing an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a chlorine atom, and n represents an integer from 0 to 2.) and contains a hydroperoxide having a thioxanthone skeleton represented by the formula. In the total of the component (b-1) and the component (b-2), the present invention relates to the curable resin composition for a decorative film in which the proportion of the component (b-2) is 30% by mass or less.

[0011] In addition, the present invention relates to a decorative film using the curable resin composition for a decorative film. [Advantages of the Invention]

[0012] The curable resin composition for a decorative film of the present invention provides a cured product having excellent surface hardness, scratch resistance, and chemical resistance while having high flexibility. [Embodiments for Carrying Out the Invention]

[0013] [Curable Resin Composition for Decorative Film] The curable resin composition for decorative films of the present invention (hereinafter also simply referred to as "curable resin composition") comprises (a) a urethane (meth)acrylate having 2 to 9 unsaturated bonds, and (b) a photopolymerization initiator.

[0014] <(a) Urethane (meth)acrylate having 2 to 9 unsaturated bonds> The present invention's (a) urethane (meth)acrylate having 2 to 9 unsaturated bonds (hereinafter also simply referred to as "urethane (meth)acrylate" or "component (a)") is a compound having urethane bonds and two or more radical polymerizable functional groups, such as ethylenically unsaturated groups, within its molecule. Urethane acrylate can be obtained, for example, by reacting a polyhydric alcohol with a polyisocyanate such as isocyanate or isocyanurate and a monofunctional (meth)acrylic monomer having a hydroxyl group. Component (a) may be used alone or in combination of two or more types.

[0015] Examples of polyhydric alcohols used as raw materials for urethane acrylates include 1,3-butanediol, 1,4-butanediol, trimethylolethane, trimethylolpropane, ditrimethylolethane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, diglycerol, glycerin, and numerous other diols such as polysiloxane polyols, poly(oxyalkylene) polyols, polyester polyols, polyether polyols, polyether polyester polyols, polyolefin polyols, poly(alkyl acrylate) polyols, and polycarbonate polyols.

[0016] Examples of isocyanates or polyisocyanates used as raw materials for urethane acrylates include tetramethylene diisocyanate, hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 3,3-dimethyl-4,4-diphenylene isocyanate, isophorone diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, 1,3-bis(isocyanate methyl)cyclohexane, 1,3-bis(α,α-dimethylisocyanate methyl)benzene, trimethylhexamethylene diisocyanate, and hydrogenated xylylene diisocyanate.

[0017] Examples of monofunctional (meth)acrylic monomers having hydroxyl groups that can be used as raw materials for urethane acrylates include trimethylolpropane diacrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and oxyethyl di(meth)acrylate isocyanurate.

[0018] (a) The number of unsaturated bonds (functional groups) in component (a) is preferably 2 to 7, and more preferably 2 to 5. If the number of unsaturated bonds (functional groups) exceeds 9, the flexibility of the cured film decreases.

[0019] (a) The molecular weight of component (a) is preferably in the range of 1,000 to 100,000 in terms of number average molecular weight, and more preferably in the range of 3,000 to 50,000. If the number average molecular weight is 1,000 or more, the flexibility of the resulting cured film will be high, while if the number average molecular weight is 100,000 or less, the viscosity of the resin composition will be suppressed, resulting in excellent compatibility with other materials and excellent coatability. <(b) Photopolymerization initiator> The (b) photopolymerization initiator of the present invention comprises a dialkyl peroxide having a thioxanthone skeleton represented by the following general formula (1) (hereinafter also simply referred to as "component (b-1)"). [ka] (In general formula (1), R 1 , R 2 , R 3 and R 4 R independently represents a methyl group or an ethyl group. 5 R represents an alkyl group with 1 to 6 carbon atoms, or a phenyl group. 6 (where n is an independent substituent, representing an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a chlorine atom, and n is an integer from 0 to 2.)

[0020] In general formula (1), R 1 , R 2 , R 3 and R 4 Each of these independently represents a methyl group or an ethyl group. In the present invention, from the viewpoint of improving the stability of dialkyl peroxides having a thioxanthone skeleton represented by general formula (1), R 1 , R 2 , R 3 and R 4 It is preferable that all of these are methyl groups.

[0021] In general formula (1), R 5 R is an alkyl group having 1 to 6 carbon atoms, or a phenyl group. The alkyl group may be linear or branched. 5 Specific examples include methyl group, ethyl group, propyl group, 2,2-dimethylpropyl group, and phenyl group. Among these, R is considered to be the easiest to synthesize thioxanthone derivatives having peroxide bonds. 5 It is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably one selected from a methyl group, an ethyl group, and a propyl group. From the viewpoint of efficiently absorbing light, R 5 It is more preferable that the group is a methyl group or an ethyl group.

[0022] In general formula (1), the substitution position of the dialkylperoxide relative to the thioxanthone is not particularly limited, but from the viewpoint of efficiently converting light energy into thermal energy, it is preferable that it is substituted at the 2nd, 3rd, or 4th position of the thioxanthone skeleton, and from the viewpoint of ease of synthesis, it is more preferable that it is substituted at the 2nd or 3rd position of the thioxanthone skeleton.

[0023] In general formula (1), R 6 The substituents are independent substituents, representing C1-C4 alkyl groups, C1-C4 alkoxy groups, or chlorine atoms. These substituents improve the light absorption characteristics of dialkyl peroxides having a thioxanthone skeleton through a push-pull effect with respect to the emission wavelength of the light source used, allowing for efficient light absorption.

[0024] In general formula (1), n ​​represents an integer from 0 to 2, but from the viewpoint of easily synthesizing dialkylperoxides having a thioxanthone skeleton, n is preferably an integer from 0 to 1, and more preferably 0.

[0025] In general formula (1), when n is an integer from 1 to 2, R 6 The substitution position is not particularly limited, but from the viewpoint of efficiently absorbing light, it is preferably at the 6th or 7th position of the thioxanthone skeleton, and from the viewpoint of easily synthesizing dialkylperoxides having a thioxanthone skeleton, it is more preferably at the 7th position of the thioxanthone skeleton.

[0026] R 6 Specific examples include alkyl groups such as methyl, ethyl, isopropyl, and n-butyl groups; alkoxy groups such as methoxy, ethoxy, n-propyloxy, sec-butyloxy, and tert-butyloxy groups; and chlorine atoms. Among these, R is considered to be the most efficient at absorbing light. 6 It is more preferable that the group is a methoxy group or an ethoxy group.

[0027] The amount of component (b-1) is 0.01 to 15 parts by mass per 100 parts by mass of component (a). From the viewpoint of curability and chemical resistance, the amount of component (b-1) is preferably 0.1 parts by mass or more, and more preferably 0.5 parts by mass or more, per 100 parts by mass of component (a), and from the viewpoint of flexibility, it is preferably 12 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of component (a). Component (b-1) may be used alone or in combination of two or more types.

[0028] Furthermore, the (b) photopolymerization initiator of the present invention may further contain (b-2) a hydroperoxide having a thioxanthone skeleton represented by the following general formula (2) (hereinafter also simply referred to as "component (b-2)"). [ka] (In formula (2), R 1 , and R 2 R independently represents a methyl group or an ethyl group. 3 (where n is an independent substituent, representing an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a chlorine atom, and n is an integer from 0 to 2.)

[0029] In general formula (2), R 1 , and R 2 R independently represents a methyl group or an ethyl group. 1 , R 2 Because the hydroperoxide having the thioxanthone skeleton has a high decomposition temperature, a methyl group is preferred from the viewpoint of improving the storage stability of the polymerizable composition.

[0030] In general formula (2), R 3 The substituents are independent and represent an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a chlorine atom. The light absorption characteristics of the hydroperoxide having the thioxanthone skeleton can be adjusted by the push-pull effect of these substituents with respect to the emission wavelength of the lamp used, allowing for efficient absorption of the irradiated light.

[0031] In general formula (2), n represents an integer from 0 to 2. From the viewpoint of facilitating the synthesis of the hydroperoxide having the thioxanthone skeleton, n is preferably an integer from 0 to 1, and more preferably 0.

[0032] In general formula (2), when n is an integer from 1 to 2, the above R 3 The substitution position is not particularly limited, but it is preferable that the substitution is at the 6th or 7th position of the thioxanthone skeleton from the viewpoint of high sensitivity to lamp light, and it is more preferable that the substitution is at the 7th position of the thioxanthone skeleton from the viewpoint of facilitating the synthesis of hydroperoxides having the thioxanthone skeleton.

[0033] R 3 Specific examples include alkyl groups such as methyl, ethyl, isopropyl, and n-butyl groups; alkoxy groups such as methoxy, ethoxy, n-propyloxy, sec-butyloxy, and tert-butyloxy groups; and chlorine atoms. Methoxy and ethoxy groups are more preferable from the viewpoint of efficiently absorbing irradiated light.

[0034] When component (b-2) is included, the proportion of component (b-2) in the total of component (b-1) and component (b-2) is preferably 30% by mass or less, from the viewpoint of ensuring excellent storage stability of the curable resin composition and preventing curing defects during photocuring, preferably 0.1% by mass or more, and more preferably 0.5% by mass or more, from the viewpoint of storage stability. Component (b-2) may be used alone or in combination of two or more types.

[0035] Furthermore, in the present invention, by using other polymerization initiators in addition to components (b-1) and (b-2) as photopolymerization initiators, the surface curability, deep curability, etc., of the curable resin composition can be improved. When selecting other polymerization initiators, the type of additives, the thickness of the cured film, etc., should be considered, as should be considered, such as (a) urethane (meth)acrylate having 2 to 9 unsaturated bonds.

[0036] Other known polymerization initiators can be used. For example, α-hydroxyacetophenone derivatives such as 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methylpropiophenone, 4'-(2-hydroxyethoxy)-2-hydroxy-2-methylpropiophenone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one; 2-methyl-4'-methylthio-2-morpholinopropiophenone, 2-benzyl-2-(N,N-dimethylamino)-1-(4-morpholino Alpha-aminoacetophenone derivatives such as phenyl)butan-1-one and 2-(dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholinophenyl)butan-1-one; acylphosphine oxide derivatives such as diphenyl-2,4,6-trimethylbenzoylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and ethyl(mesitylcarbonyl)phenylphosphineate; 1-[4-(phenylthio)phenyl]octane-1,2-dione-2-(O-benzoyloxy Oxime ester derivatives such as 1-[({1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethylidene}amino)oxy]ethanone; halomethyltriazine derivatives such as 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-(3,4-dimethoxystyryl)-4,6-bis(trichloromethyl)1,3,5-triazine, and 2-(4-ethoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine; 2,2-dimethyl Benzyl ketal derivatives such as toxic-2-phenylacetophenone; thioxanthone derivatives such as isopropylthioxanthone; benzophenone derivatives such as 4-(4-methylphenylthio)benzophenone; coumarin derivatives such as 3-benzoyl-7-diethylaminocoumarin and 3,3'-carbonylbis(7-diethylaminocoumarin); imidazole derivatives such as 2-(2-chlorophenyl)-1-[2-(2-chlorophenyl)-4,5-diphenyl-1,3-diazole-2-yl]-4,5-diphenylimidazole;Examples include organic peroxides such as 3,3',4,4'-tetrakis(tert-butylperoxycarbonyl)benzophenone and dibenzoyl peroxide; azo compounds such as azobisisobutyronitrile; and camphorquinone. Other polymerization initiators may be used alone or in combination of two or more.

[0037] <(c) Solvent> To improve viscosity, coatability, and the smoothness of the cured film, the curable resin composition may further contain (c) a solvent (hereinafter also simply referred to as "component (c)").

[0038] (c) Examples of solvents include acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, methanol, ethanol, etc. (c) The solvent may be used alone or in combination of two or more types.

[0039] (c) The solvent can be used to adjust the viscosity when forming a coating film of the curable resin composition of the present invention. From the viewpoint of coatability and transparency of the coating film, the solid content concentration of the curable resin composition is preferably 5 to 90% by mass, and more preferably 10 to 80% by mass.

[0040] <Other hardening components> The curable resin composition may further contain curable components having ethylenically unsaturated double bonds, such as (meth)acrylate polymers, (meth)acrylate oligomers, and (meth)acrylate monomers, which have different numbers of functional groups and structures other than urethane (meth)acrylate having 2 to 9 unsaturated bonds. Examples of such curable components include acrylic (meth)acrylate, polyester (meth)acrylate oligomer, epoxy (meth)acrylate oligomer, and (meth)acrylate monomer.

[0041] <Filler> The curable resin composition may further contain fillers. By including fillers, the physical properties of the cured film, such as scratch resistance, can be improved. Examples of fillers include fine particles such as alumina and nanosilica. Among these, the use of alumina fine particles is preferred.

[0042] The average primary particle size of the filler is preferably 1 to 100 nm, and more preferably 50 nm or less, from the viewpoint of dispersibility and transparency.

[0043] <Other additives, etc.> The curable resin composition may optionally contain known additives such as sensitizers, thermosetting agents, crosslinking agents, crosslinking accelerators, silane coupling agents, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), antioxidants, fillers, colorants (pigments, dyes, etc.), UV absorbers, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, thickeners, flame retardants, inorganic compounds, and electromagnetic wave absorbing fillers, either individually or in combination of two or more, as long as they do not impair the properties of this embodiment.

[0044] <Method for preparing a curable resin composition> The method for preparing the curable resin composition is not particularly limited. The above components may be mixed in predetermined proportions and then mixed according to conventional methods using a paint shaker, bead mill, sand grind mill, ball mill, attritor mill, two-roll mill, three-roll mill, etc.

[0045] <Decorative film> The decorative film of the present invention is obtained using a curable resin composition. The decorative film may be, for example, a decorative film in which a curable resin composition is laminated on a base film, or it may be a decorative film consisting of a curable resin composition alone.

[0046] The coating method for the curable resin composition can be any known coating method, and the curing method for the curable resin composition can be selected according to the production process, such as a pre-cure method where it is cured before decorative molding, an after-cure method where it is cured after decorative molding, or a semi-curing method where it is in a semi-cured state before decorative molding and fully cured after decorative molding. Examples of decorative molding for decorative films include primary decoration such as in-mold molding and sheet molding, and secondary decoration such as film lamination / transfer, printing, and vacuum deposition.

[0047] The thickness of the cured film formed from the curable resin composition is preferably in the range of 0.1 μm to 250 μm, more preferably 0.5 μm to 100 μm, and particularly preferably 1 μm to 50 μm. When the film thickness is within the above range, the film strength is good, and the surface hardness, scratch resistance, and chemical resistance of the cured film are also good.

[0048] The method for curing the curable resin composition is not particularly limited, but it is preferable to cure it by irradiation with active energy rays such as electron beams, ultraviolet rays, visible light, or radiation. The exposure amount of the active energy rays can be appropriately set according to the wavelength and intensity of the active energy rays, the composition of the curable resin composition, and the film thickness. As an example, the exposure amount in the UV-A region is 10 to 5,000 mJ / cm². 2 Preferably, the concentration is 50-3,000 mJ / cm². 2 It is more preferable that this is the case. In addition, a heating step may be performed before or after the step of irradiation with active energy rays.

[0049] Furthermore, because the curable resin composition of the present invention has flexibility and hard coating properties in its cured film, it is also useful for applications such as hard coating films for optical lenses (prism sheets, collimator lenses, Fresnel lenses, lenticular lenses, back-reflecting lenses, holograms, etc.), anti-reflective films, and decorative sheets (interior materials for floors, walls, ceilings, etc. of buildings). [Examples]

[0050] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples.

[0051] <Preparation of a curable resin composition for decorative films> Each component was mixed in the proportions shown in Table 1 to obtain the curable resin compositions of Examples 1-9 and Comparative Examples 1-3. These curable resin compositions were evaluated according to the following method.

[0052] [Evaluation Method] (curable) The curable resin composition obtained above was coated onto an easily adhesive treated PET film (Cosmoshine A4300, manufactured by Toyobo) using a bar coater to create a uniform coating film with a thickness of approximately 30 μm. Next, an illuminance of 4.0 W / cm² was applied using a 385 nm LED light source. 2 Light irradiation was performed at a line speed of 6 m / min. The cured surface was palpated, and the number of irradiations required until the curable resin composition no longer stuck to the hand was evaluated as curability.

[0053] (Flexibility) The curable resin composition prepared above was injected into a glass plate with a 0.5 mm thick spacer in between, and an illuminance of 4.0 W / cm² was applied using a 385 nm LED light source. 2 A cured film was obtained by light irradiation under the conditions of a line speed of 6 m / min and 3 irradiation cycles. The obtained cured film was wrapped around SUS rods with diameters of 10 mm and 15 mm, and the change in appearance was evaluated visually according to the following criteria. An evaluation of ◎ or ○ is considered a pass, with ◎ being more preferable. ◎: No cracks were found in the hardened film wrapped around 10mm and 15mm diameter stainless steel rods. ○: Cracks were observed in the hardened film wrapped around a 10mm diameter stainless steel rod, but no cracks were found in the hardened film wrapped around a 15mm diameter stainless steel rod. ×: Cracks were found in the hardened film wrapped around SUS rods with diameters of 10 mm and 15 mm.

[0054] (Surface hardness (pencil hardness)) The curable resin composition obtained above was coated onto an easily adhesive treated PET film (Cosmoshine A4300, manufactured by Toyobo) using a bar coater to create a uniform coating film with a thickness of approximately 30 μm. Next, an illuminance of 4.0 W / cm² was applied using a 385 nm LED light source. 2 A cured film was obtained by light irradiation under the conditions of a line speed of 6 m / min and 3 irradiations. In accordance with JIS K5600, the hardest pencil that did not leave a scratch was used to determine the pencil hardness when a pencil was scratched approximately 10 mm while applying a load of 750 g at a 45° angle to the prepared cured film. The evaluation criteria for pencil hardness are as follows: An evaluation of ◎ or ○ is considered a pass, with ◎ being more preferable. ◎: The pencil has a hardness of 2H or higher. ○: The pencil has a hardness of H. ×: The pencil hardness is less than H.

[0055] (Chemical resistance) The curable resin composition obtained above was coated onto an easily adhesive treated PET film (Cosmoshine A4300, manufactured by Toyobo) using a bar coater to create a uniform coating film with a thickness of approximately 30 μm. Next, an illuminance of 4.0 W / cm² was applied using a 385 nm LED light source. 2 A cured film was obtained by light irradiation under the conditions of a line speed of 6 m / min and 3 irradiations. A commercially available sunscreen cream (product name "Neutrogena," manufactured by Johnson & Johnson, SPF 100) was applied to the surface of the prepared cured film, and after standing at a temperature of 80°C for 180 minutes, the degree to which the surface of the cured film changed from transparent to white after wiping off the sunscreen cream with a dry cloth was visually confirmed. The evaluation criteria for chemical resistance are as follows. An evaluation of ◎ or ○ is considered a pass, with ◎ being more preferable. ◎: The coating is transparent and no changes are observed. ○: Slight whitening is observed in some areas. ×: Whitening was observed in part or throughout the plant.

[0056] (Scratch resistance) The curable resin composition obtained above was coated onto an easily adhesive treated PET film (Cosmoshine A4300, manufactured by Toyobo) using a bar coater to create a uniform coating film with a thickness of approximately 30 μm. Next, an illuminance of 4.0 W / cm² was applied using a 385 nm LED light source. 2 A cured film was obtained by light irradiation under the conditions of a line speed of 6 m / min and 3 irradiation cycles. The prepared cured film was subjected to 10 passes of #0000 steel wool with a load of 200 g, and the surface of the cured film was observed visually. The evaluation criteria for scratch resistance are as follows. An evaluation of ◎ or ○ is considered a pass, with ◎ being more preferable. ◎: No peeling or damage to the membrane was observed. ○: A small, fine scratch is visible on a part of the membrane. ×: Muscle-like damage is observed throughout the membrane, or delamination of the membrane occurs.

[0057] (Storage stability) The curable resin composition prepared above was placed in a brown glass bottle, shielded from light with aluminum foil, and then left to stand in a constant temperature incubator at 60°C, simulating transport and storage conditions. After standing for a predetermined period, the change in the appearance of the curable resin composition was visually evaluated according to the following criteria: "◎" if no gelation was visually observed after 3 months of storage, "○" if no gelation was visually observed after 2 months of storage, and "×" if gelation was visually observed after 2 months of storage. Gelation refers to a state in which the composition does not flow when the container is tilted. In the evaluation, "◎" or "○" is considered a pass, with "◎" being more preferable. ◎: No gelation was observed visually after 3 months of storage. ○: No gelation was observed visually after 2 months of storage. ×: After 2 months of storage, gelation was visually confirmed.

[0058] Further details regarding the abbreviations and other terms listed in Table 1 are as follows: UV-7000B: 2-3 functional urethane (meth)acrylate (manufactured by Mitsubishi Chemical) UV-3700B: Bifunctional urethane (meth)acrylate (manufactured by Mitsubishi Chemical) M-306: Pentaerythritol tritetraacrylate (manufactured by Toagosei Co., Ltd.) TPO: Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (manufactured by IGM Resins BV) MEK: Methyl ethyl ketone

[0059] Compounds 1, 2, 10, and 11, listed in Table 1, were synthesized according to the method described in International Publication No. 2023 / 190161. Details of compounds 1, 2, 10, and 11 are shown in Table 2.

[0060] [Table 1]

[0061] [Table 2]

[0062] As shown in Table 1, the curable resin compositions of each example exhibited good curability, chemical resistance, surface hardness, scratch resistance, and excellent flexibility. On the other hand, the compositions of each comparative example showed insufficient curability or inferior flexibility and chemical resistance.

Claims

1. (a) A curable resin composition for decorative films comprising a urethane (meth)acrylate having 2 to 9 unsaturated bonds, and (b) a photopolymerization initiator. The photopolymerization initiator (b) is (b-1) General formula (1): 【Chemistry 1】 (In general formula (1), R １ , R ２ , R ３ and R ４ Each of these independently represents either a methyl group or an ethyl group, R ５ R represents an alkyl group or phenyl group having 1 to 6 carbon atoms. ６ The compound comprises a dialkyl peroxide having a thioxanthone skeleton represented by ), where is an independent substituent, representing an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a chlorine atom, and n represents an integer from 0 to 2. The curable resin composition for decorative films is characterized in that the (b-1) component is 0.01 to 15 parts by mass with respect to 100 parts by mass of the (a) component.

2. The (b) photopolymerization initiator further comprises (b-2) general formula (2): 【Chemistry 2】 (In general formula (2), R １ , and R ２ independently represent a methyl group or an ethyl group, and R ３ is an independent substituent and represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a chlorine atom, and n represents an integer from 0 to 2.) containing a hydroperoxide having a thioxanthone skeleton represented by The curable resin composition for decorative films according to claim 1, characterized in that the proportion of component (b-2) in the total of component (b-1) and component (b-2) is 30% by mass or less.

3. A decorative film using the curable resin composition for decorative films according to claim 1 or 2.

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