Transfer film and method for producing same

Abstract

Provided is a transfer film in which an ultraviolet-curable resin layer is a thin film, and in which the ultraviolet-curable resin layer and a release layer can be easily separated even before and after high-temperature heating. A transfer film having a release layer and an ultraviolet-curable resin layer in this order on at least one surface of a support substrate, the transfer film being characterized in that the interlayer release force between the ultraviolet-curable resin layer and the release layer of the transfer film after heating at 150 DEG C is 0.04 N / 25 mm or more and 0.12 N / 25 mm or less, and the thickness of the ultraviolet-curable resin layer is 0.5 [mu] m or more and 2.5 [mu] m or less.

Description

TECHNICAL FIELD

[0001] The present application relates to a transfer film having excellent peeling properties based on heating temperature and a manufacturing method thereof. BACKGROUND

[0002] A polarizing plate is disposed in a display (liquid crystal, organic EL) for a thin television, a mobile phone, and the like. The polarizing plate bears the role of passing only light in a certain direction, and the performance of the polarizing plate significantly affects the performance of the display. The polarizing plate is generally composed of a polarizing sheet (which is formed of a polyvinyl alcohol film or the like to which iodine or dye is adsorbed and oriented) and a protective film attached to the polarizing sheet.

[0003] In recent years, the market for mobile device applications such as smartphones and tablet terminals has been expanding, and there is an increasing demand for thinning of displays, and thinning of components such as polarizing plate protective films that constitute a polarizing plate is also required.

[0004] In order to meet the requirement for thinning of the protective film, Patent Literature 1 proposes a transfer sheet as a method of transferring only a resin layer to a molded body, the transfer sheet being composed of a support base material, a release layer, and a resin layer, and using a silicone acrylic resin that becomes a firm cured film by forming a silicon crosslink as a main material and a polydimethylsiloxane-based copolymer as a sub-material in the release layer, thereby enabling the release layer and the functional layer to be smoothly peeled off.

[0005] Patent Literature 2 proposes a laminate composed of a support base material, a release layer, and a resin layer, which does not have unevenness, does not impair the appearance quality such as transparency, and enables transfer to be performed uniformly in-plane.

[0006] It is described in Patent Literature 3 that if the resin layer is 3 μm or more, deformation caused by shrinkage of a polarizing sheet in a polarizing plate and penetration of moisture in the air into the polarizing sheet can be suppressed, and it is therefore considered to be preferable.

[0007] PRIOR ART DOCUMENTS

[0008] PATENT LITERATURE

[0009] Patent Literature 1: Japanese Patent Application Publication No. 2004-034385

[0010] Patent Literature 2: Japanese Patent Application Publication No. 2020-37251

[0011] Patent Literature 3: Japanese Patent Application Publication No. 2018-084615 SUMMARY

[0012] PROBLEMS TO BE SOLVED BY THE INVENTION

[0013] In a molding process in which an adherend provided with an adhesive is attached to the resin layer side using a transfer film having a release layer and a resin layer, in order to dry the adhesive, a heating treatment at 150°C or higher is performed. Then, a process of peeling the transfer film from the adhesive layer is entered, but the methods described in Patent Documents 1 and 2 have the following problems: the adhesion of the release layer of the transfer film increases, and problems such as separation of the release layer within the layer and remaining on the adhesive layer side, or breakage of the transfer film itself, occur.

[0014] In addition, if the thickness of the resin layer is 3 μm or more, deformation caused by shrinkage of the polarizing sheet in the polarizing plate, and penetration of moisture in the air into the polarizing sheet can be suppressed, and thus it is considered to be preferable, but there is a problem of an increase in cost, and thinning of the polarizing sheet is urgently desired.

[0015] Therefore, the object of the present application is to provide a transfer film in which the ultraviolet curable resin layer is a thin film, and the ultraviolet curable resin layer can be easily peeled from the release layer before and after high-temperature heating.

[0016] Means for solving the problem

[0017] In order to solve the above problem, the present application has the following configuration. That is,

[0018] (1) A transfer film which has a release layer and an ultraviolet curable resin layer in this order on at least one surface of a support substrate, wherein the interlayer peeling force between the ultraviolet curable resin layer and the release layer of the transfer film after heating at 150°C is 0.04 N / 25 mm or more and 0.12 N / 25 mm or less, and the thickness of the ultraviolet curable resin layer is 0.5 μm or more and 2.5 μm or less.

[0019] (2) The transfer film according to the above (1), wherein the thickness of the release layer is 350 nm or more and 500 nm or less.

[0020] (3) The transfer film according to the above (1) or (2), wherein the interlayer peeling force between the ultraviolet curable resin layer and the release layer of the transfer film after peeling before heating at 150°C is 0.04 N / 25 mm or more.

[0021] (4) The transfer film according to any one of the above (1) to (3), wherein the haze of the adherend after heating at 150°C and peeling is 0.50% or less.

[0022] (5) The method for producing a transfer film according to claim 1, wherein a release layer is formed on a support substrate using a release layer resin composition, and the release layer resin composition has a peak at 1118 cm -1The resin composition for a release layer is one in which the peak intensity of the peak at 1,700 cm"1is 1.5 times or more relative to the peak intensity of the peak at 1,700 cm"1of the resin composition for a release layer left to stand for 0 hours after stirring.

[0023] Effects of the Invention

[0024] According to the present application, a transfer film can be obtained, which, even if heated to 150°C or higher in the forming process of the transfer film and the adherend due to heat treatment such as drying of the adhesive, does not cause separation or residue of the release layer within the release layer, nor breakage of the transfer film itself in the peeling process of the transfer film thereafter. BRIEF DESCRIPTION OF DRAWINGS

[0025] [Layer configuration of a transfer film] Figure 1 is a layer configuration diagram of an example of a transfer film in which a release layer and an ultraviolet-curable resin layer are layered on a support substrate. DETAILED DESCRIPTION

[0026] [Transfer film, and ultraviolet-curable resin layer, support substrate]

[0027] The transfer film of the present application has, on at least one face of a support substrate, a release layer and an ultraviolet-curable resin layer in this order from the support substrate side.

[0028] [Support substrate]

[0029] The resin constituting the support substrate used in the transfer film of the present application can be any of a thermoplastic resin, a thermosetting resin, can be a homopolymer resin, or can be a copolymer or a blend of two or more. The resin constituting the support substrate is preferably one having good moldability, and from this point of view, a thermoplastic resin is more preferable.

[0030] As examples of the thermoplastic resin, polyethylene, polypropylene, polystyrene, polymethylpentene, and the like polyolefin resins, alicyclic polyolefin resins, nylon 6, nylon 66, and the like polyamide resins, aromatic polyamide resins, polyimide resins, polyester resins, polycarbonate resins, polyarylate resins, polyacetal resins, polyphenylene sulfide resins, tetrafluoroethylene resins, trifluoroethylene resins, chlorotrifluoroethylene resins, tetrafluoroethylene-hexafluoropropylene copolymers, vinylidene fluoride resins, and the like fluororesins, acrylic resins, methacrylic resins, polyacetal resins, polyglycolic acid resins, polylactic acid resins, and the like can be used.

[0031] The thermoplastic resin is preferably one having sufficient stretchability and followability. From the viewpoint of strength and heat resistance, the thermoplastic resin is particularly more preferably a polyester resin, a polycarbonate resin, an acrylic resin, or a methacrylic resin.

[0032] The polyester resin in the present application refers to a general term of a high molecule with an ester bond as a main binding chain, and is obtained by polycondensation of an acid component and its ester and a diol component. As specific examples, polyethylene terephthalate, polytrimethylene terephthalate, polyethylene 2,6-naphthalate, polybutylene terephthalate, and the like can be given. In addition, a polyester resin in which other dicarboxylic acid and its ester, a diol component as an acid component, and a diol component are copolymerized can also be used. Among these, polyethylene terephthalate and polyethylene 2,6-naphthalate are particularly preferable in terms of transparency, dimensional stability, heat resistance, and the like.

[0033] On the other hand, in order to check the optical properties in the manufacturing process of the transfer film, the support substrate is preferably a material that is transparent and has low birefringence, and cellulose ester and cyclic olefin are preferable from the viewpoint of low birefringence. As commercially available norbornene-based polymers, ARTON (manufactured by JSR Corporation), ZEONEX, ZEONOR (all manufactured by ZEON Corporation, Japan), TOPAS (manufactured by Polyplastics Corporation), and the like can be used.

[0034] As examples of the thermosetting resin, a phenol resin, an epoxy resin, a urea resin, a melamine resin, an unsaturated polyester resin, a polyurethane resin, a polyimide resin, a silicone resin, and the like can be used.

[0035] In addition, various additives such as an antioxidant, an antistatic agent, a crystallization nucleating agent, an inorganic particle, an organic particle, a viscosity reducer, a heat stabilizer, a lubricant, an infrared absorber, an ultraviolet absorber, a dopant for adjusting the refractive index, and the like can be added to the support substrate. The support substrate can be any of a single layer configuration and a laminated configuration.

[0036] Various surface treatments can also be performed before forming the ultraviolet-curable resin layer described later. As examples of the surface treatment, chemical treatment, mechanical treatment, corona discharge treatment, flame treatment, ultraviolet irradiation treatment, high-frequency treatment, glow discharge treatment, active plasma treatment, laser treatment, mixed acid treatment, and ozone oxidation treatment can be given. Among these, glow discharge treatment, ultraviolet irradiation treatment, corona discharge treatment, and flame treatment are preferable, and glow discharge treatment and ultraviolet treatment are further preferable. In addition, a plurality of functional layers such as an easy-adhesion layer, an antistatic layer, a primer layer, an ultraviolet absorbing layer, and the like can also be provided in advance on the surface of the support substrate.

[0037] As the support substrate, there is no particular limitation as long as the transfer of the ultraviolet-curable resin layer can be achieved, and a support substrate having a release layer on the surface in contact with the ultraviolet-curable resin layer is preferably used.

[0038] [Release Layer]

[0039] The material of the release layer is not particularly limited, and is preferably formed from the release layer resin composition described later, and is preferably formed on the surface of the support substrate by coating, drying, and curing using the manufacturing method of the release layer described later. The release layer can be composed of multiple layers from the viewpoint of imparting adhesion, antistatic properties, solvent resistance, and the like, on the support substrate side.

[0040] The thickness of the release layer is not particularly limited, and is preferably 350 to 500 nm, and more preferably 400 to 450 nm, from the viewpoint of in-plane uniformity, quality, and peeling force of the release layer.

[0041] The release layer refers to a layer formed using a release layer resin composition. The release layer resin composition is preferably a release layer resin composition in which the peak intensity at 1118 cm -1 -1.5 times or more the peak intensity at 0 hours after stirring, as measured using FT-IR, of the release layer resin composition. The release layer resin composition is preferably a release layer resin composition in which the peak intensity at 1118 cm -1The peak intensity at 1118 cm"1 of the resin composition for a release layer is preferably 1.5 times or more relative to the peak intensity of the resin composition for a release layer after stirring for 0 hours. This makes the interlayer peeling strength between the ultraviolet-curable resin layer of the transfer film and the release layer, the interlayer peeling strength between the ultraviolet-curable resin layer of the transfer film and the release layer after heating at 150°C, and the haze of the adherend immediately after peeling, which are measured by the methods described below, fall within the following preferred ranges. The interlayer peeling strength between the ultraviolet-curable resin layer of the transfer film and the release layer is preferably 0.04 N / 25 mm or more. In addition, the interlayer peeling strength between the ultraviolet-curable resin layer of the transfer film and the release layer after heating at 150°C is preferably 0.04 N / 25 mm or more and 0.12 N / 25 mm or less. The haze of the adherend after peeling is preferably 0.50% or less. If the haze of the adherend after peeling exceeds 0.50%, the transparency of the adherend decreases, and the visual recognition deteriorates, so it is sometimes difficult to use as an article of the present use. By making the interlayer peeling strength between the ultraviolet-curable resin layer of the transfer film and the release layer, and the interlayer peeling strength between the ultraviolet-curable resin layer of the transfer film and the release layer after heating at 150°C fall within the preferred ranges, the occurrence of peeling of the adherend from the transfer film is further eliminated in the molding process and the heating process after the transfer film is attached to the adherend, and the transfer film can be peeled from the adherend in the peeling process thereafter, and the haze of the adherend after peeling can be made to fall within the aforementioned preferred range. If the interlayer peeling strength between the ultraviolet-curable resin layer of the transfer film and the release layer is less than 0.04 N / 25 mm, the transfer film sometimes peels from the adherend before the molding process or the heating process after the transfer film is attached to the adherend. In addition, if the interlayer peeling strength between the ultraviolet-curable resin layer of the transfer film and the release layer after heating at 150°C is less than 0.04 N / 25 mm, the transfer film sometimes peels from the adherend before the peeling process. In addition, if the interlayer peeling strength between the ultraviolet-curable resin layer of the transfer film and the release layer after heating at 150°C exceeds 0.12 N / 25 mm, the transfer film sometimes cannot be peeled from the adherend in the peeling process, and the problem that the transfer film cannot be peeled or, even if it can be peeled, the haze of the adherend after peeling cannot be made to fall within the aforementioned preferred range sometimes occurs.

[0042] For the resin composition for a release layer in the present application, the peak intensity at 1118 cm"1 of the resin composition measured by FT-IR is preferably 1.5 times or more relative to the peak intensity of the resin composition for a release layer after stirring for 0 hours. There is no particular limitation as long as the peak intensity at 1118 cm"1 of the resin composition measured by FT-IR is 1.5 times or more relative to the peak intensity of the resin composition for a release layer after stirring for 0 hours, and an alkyd-based resin, a polyolefin-based resin, a long-chain alkyl-containing resin, a fluorine-based resin, a silicone-based resin, a mixed or copolymerized resin of an organic and a silicone-based resin, or the like is preferred. Furthermore, a mixed resin of a melamine-based resin and a silicone-based resin is more preferred. -1 For the resin composition for a release layer in the present application, the peak intensity at 1118 cm"1 of the resin composition measured by FT-IR is preferably 1.5 times or more relative to the peak intensity of the resin composition for a release layer after stirring for 0 hours. There is no particular limitation as long as the peak intensity at 1118 cm"1 of the resin composition measured by FT-IR is 1.5 times or more relative to the peak intensity of the resin composition for a release layer after stirring for 0 hours, and an alkyd-based resin, a polyolefin-based resin, a long-chain alkyl-containing resin, a fluorine-based resin, a silicone-based resin, a mixed or copolymerized resin of an organic and a silicone-based resin, or the like is preferred. Furthermore, a mixed resin of a melamine-based resin and a silicone-based resin is more preferred.

[0043] In addition, it is preferable to include a binder resin. As the binder resin, urethane-based resins, acetal-based resins, polyamide-based resins, melamine-based resins, polyol resins, cellulose resins, and polyvinyl alcohol, etc. can be given, and urethane-based resins and acetal-based resins are preferably used. Among these, polyol resins are more preferable.

[0044] The peak at 1118 cm"1"of the resin composition measured by FT-IR indicates an ether bond. When the peak intensity at 1118 cm"1"of the release layer resin composition measured by FT-IR is less than 1.5 times the peak intensity of the release layer resin composition after stirring and 0 hours of standing, sometimes the polymerization of the release layer resin composition is not promoted, sometimes the peeling force of the transfer film after heating is significantly increased, and sometimes haze increases due to the release layer being damaged, separated, and remaining in the ultraviolet-curable resin layer. By making the peak intensity at 1118 cm"1"of the release layer resin composition measured by FT-IR 1.5 times or more the peak intensity of the release layer resin composition after stirring and 0 hours of standing, the above problems can be better solved. -1 -1 The peak at 1118 cm"1"of the release layer resin composition measured by FT-IR indicates an ether bond. When the peak intensity at 1118 cm"1"of the release layer resin composition measured by FT-IR is less than 1.5 times the peak intensity of the release layer resin composition after stirring and 0 hours of standing, sometimes the polymerization of the release layer resin composition is not promoted, sometimes the peeling force of the transfer film after heating is significantly increased, and sometimes haze increases due to the release layer being damaged, separated, and remaining in the ultraviolet-curable resin layer. By making the peak intensity at 1118 cm"1"of the release layer resin composition measured by FT-IR 1.5 times or more the peak intensity of the release layer resin composition after stirring and 0 hours of standing, the above problems can be better solved. -1

[0045] The method of forming the release layer on the support substrate is not particularly limited, and it is preferable to form a coating layer by coating the release layer coating composition described below using a dip coating method, a roll coating method, a wire bar coating method, a gravure coating method, a die coating method (U.S. Patent No. 2681294 specification), etc., and a gravure coating method or a die coating method is preferable.

[0046] Next, the coating layer coated on the support substrate or the like is dried. From the viewpoint of completely removing the solvent from the obtained coating layer and promoting the curing of the coating film, heating of the coating film is preferably performed in the drying step.

[0047] As the drying method, heat transfer drying (intimate contact with a high-heat object), convection heat transfer (hot air), radiation heat transfer (infrared rays), and others (microwaves, induction heating), etc. can be given. Among these, in the manufacturing method of the present application, since it is necessary to accurately make the drying speed uniform in the width direction as well, a method using convection heat transfer or radiation heat transfer is preferable.

[0048] Furthermore, a further curing operation (curing step) can be performed by heat or irradiation of energy rays. In the case of curing by heat in the curing step, it is preferable to be from room temperature to 200°C, and from the viewpoint of the activation energy of the curing reaction, it is more preferable to be 100°C or higher and 200°C or lower, and it is further preferable to be 130°C or higher and 200°C or lower.

[0049] ​​In addition, in the case of curing using an energy ray, from the viewpoint of general use, electron beam (EB line) and / or ultraviolet ray (UV line) is preferred. In addition, as the type of ultraviolet ray lamp used when irradiating ultraviolet rays, for example, a discharge lamp type, a flash type, a laser type, an electrodeless lamp type, and the like can be given. In the case of ultraviolet curing using a high-pressure mercury lamp as a discharge lamp type, it is preferable to perform ultraviolet irradiation under the condition that the irradiance of ultraviolet rays is preferably 100 to 3,000 (mW / cm 2 ), more preferably 200 to 2,000 (mW / cm 2 ), further preferably 300 to 1,500 (mW / cm 2 ), and it is preferable to perform ultraviolet irradiation under the condition that the cumulative light quantity of ultraviolet rays is preferably 100 to 3,000 (mJ / cm 2 ), more preferably 200 to 2,000 (mJ / cm 2 ), further preferably 300 to 1,500 (mJ / cm 2 ). Here, the irradiance of ultraviolet rays is the irradiation intensity per unit area, and varies depending on the lamp output, the luminous spectrum efficiency, the diameter of the light-emitting bulb, the design of the reflector, and the distance from the light source to the irradiated object. However, the irradiance does not vary with the conveyance speed. In addition, the cumulative light quantity of ultraviolet rays is the irradiation energy per unit area, and is the total amount of photons that reach the surface. The cumulative light quantity is inversely proportional to the irradiation speed passing from the light source, and is proportional to the number of irradiation times and the number of lamps.

[0050] It is preferable to dry and cure the coating layer formed on the support base material in the above-described manner, thereby forming a release layer on the support base material.

[0051] [Coating composition for ultraviolet-curable resin layer]

[0052] The ultraviolet-curable resin layer in the present application refers to a layer formed on the release layer, and can be peeled off and transferred from the release layer. The criterion for determining peelability is evaluated using the crosshatch method described in JIS K5600-5-6:1999, and a case where the classification is 4 or more is regarded as peelable, and a case where the classification is 0 to 3 is regarded as non-peelable. All parts including the aforementioned ultraviolet-curable resin layer and release layer, and the support base material are collectively referred to as a transfer film. In the case where only one layer is formed on the release layer, the one layer becomes the ultraviolet-curable resin layer, and in the case where two or more layers are formed on the release layer, the two or more layers other than the release layer are regarded as one ultraviolet-curable resin layer.

[0053] The manufacturing method of the transfer film is not particularly limited, and the transfer film of the present application can be obtained by the following process: coating the coating composition for the ultraviolet-curable resin layer on the release layer of the aforementioned support substrate, and drying and curing as necessary.

[0054] Here, the so-called layer refers to a portion that can be distinguished by having a boundary surface with an adjacent portion in the thickness direction, from the surface side of the transfer film, and has a finite thickness. More specifically, it refers to a portion that is distinguished by the presence or absence of a discontinuous boundary surface when the cross section of the aforementioned transfer film is observed in cross section using an electron microscope (transmission type, scanning type) or an optical microscope. Therefore, even in the case where there is a change in composition in the thickness direction of the ultraviolet-curable resin layer but there is no aforementioned boundary surface therebetween, it is treated as one layer.

[0055] The transfer film of the present application can be in any of a planar state or a three-dimensional shape, as long as it has an ultraviolet-curable resin layer that exhibits the aforementioned properties. The thickness of the aforementioned ultraviolet-curable resin layer as a whole is preferably 0.5 μm or more and 2.5 μm or less, and more preferably 1.5 μm or more and 2.0 μm or less. In the case where the thickness of the ultraviolet-curable resin layer as a whole is less than 0.5 μm, the scratch resistance sometimes decreases, and in the case where it is thicker than 2.5 μm, there is sometimes a problem such as an increase in cost.

[0056] The aforementioned ultraviolet-curable resin layer can have glossiness, fingerprint resistance, moldability, designability, damage resistance, stain resistance, solvent resistance, antireflection, antistatic properties, electrical conductivity, heat ray reflection, near-infrared absorption, electromagnetic wave shielding, easy adhesion, and other functions.

[0057] In addition, one or more layers can be further formed on the aforementioned ultraviolet-curable resin layer, and for example, an ultraviolet-curable resin layer having the aforementioned functions, an adhesive layer, an electronic circuit layer, a printing layer, an optical adjustment layer, and the like, and other ultraviolet-curable resin layers can be provided.

[0058] [Manufacturing method of transfer film]

[0059] The manufacturing method of the transfer film of the present application is a manufacturing method in which a release layer and an ultraviolet-curable resin layer are sequentially formed on at least one face of a support substrate, wherein a release layer-forming resin composition having a peak intensity at 1118 cm -1 -1.5 times or more relative to the peak intensity of the release layer-forming resin composition after stirring and 0 hours of standing (so-called standing time of 0 hours means defined as 0 hours or less in units of "hours" (hour) with the first digit after the decimal point rounded off) measured using FT-IR is used to form a release layer on a support substrate.

[0060] The method for forming the ultraviolet-curable resin layer is preferably a production method in which the above-mentioned preferred ultraviolet-curable resin layer composition is applied onto the above-mentioned preferred release layer of the support substrate, followed by drying and curing, thereby forming the ultraviolet-curable resin layer. The application method is not particularly limited and can be appropriately selected from dip coating, roll coating, wire bar coating, gravure coating, die coating (U.S. Patent No. 2681294), and the like. Here, it is important that the surface properties of the ultraviolet-curable resin layer satisfy the above-mentioned conditions, and the production method can be one capable of forming an ultraviolet-curable resin layer in which the resin composition differs in the thickness direction. In the case of forming an ultraviolet-curable resin layer in which the resin composition differs in the thickness direction, the production method of the transfer film is preferably one in which at least two or more kinds of ultraviolet-curable resin layer compositions are applied successively or simultaneously, followed by drying and curing, and is more preferably one in which at least two or more kinds of ultraviolet-curable resin layer compositions are applied simultaneously.

[0061] In the drying, the coating film applied onto the support substrate or the like is dried. In the drying step, heating of the coating film is preferably accompanied in addition to complete removal of the solvent from the obtained transfer film.

[0062] As the heating method in the drying step, methods such as heat transfer drying (adhesion to a high-heat object), convection heat transfer (hot air), radiation heat transfer (infrared rays), and others (microwaves, induction heating) can be given. Among them, since the drying speed needs to be accurately made uniform also in the width direction, the method using convection heat transfer or radiation heat transfer is preferred.

[0063] Subsequent to the drying step, a further curing operation (curing step) can be performed by heating or irradiation of active energy rays.

[0064] As the active energy rays, electron beams (EB rays) and / or ultraviolet rays (UV rays) are preferred from the viewpoint of general use. In the case of curing using ultraviolet rays, the oxygen concentration is preferably as low as possible from the viewpoint of preventing oxygen inhibition, and more preferably, curing is performed under a nitrogen atmosphere (nitrogen purge). When the oxygen concentration is high, the outermost surface curing is inhibited, the surface curing is weakened, and the toughness is reduced. In addition, as the type of ultraviolet lamp used when irradiating ultraviolet rays, for example, a discharge lamp type, a flash type, a laser type, an electrodeless lamp type, and the like can be given. In the case of using a high-pressure mercury lamp as the discharge lamp type, the irradiance of the ultraviolet rays is preferably 100 to 3,000 mW / cm 2 , more preferably 200 to 2,000 mW / cm 2 , and further preferably 300 to 1,500 mW / cm 2It is preferable to perform the ultraviolet irradiation under conditions where the cumulative light amount of the ultraviolet light is 100 to 3,000 mJ / cm 2 , more preferably 200 to 2,000 mJ / cm 2 , and further preferably 300 to 1,500 mJ / cm 2 . Here, the ultraviolet light intensity is the irradiation intensity per unit area, and varies depending on the lamp output, the light spectrum efficiency, the diameter of the light bulb, the design of the reflector, and the distance from the light source to the irradiated object. However, the intensity does not vary with the conveyance speed. In addition, the cumulative light amount of the ultraviolet light is the irradiation energy per unit area, and is the total amount of photons that reach the surface. The cumulative light amount is inversely proportional to the irradiation speed from the light source, and is proportional to the number of irradiations and the number of lamps.

[0065] [Composition for ultraviolet-curable resin layer]

[0066] The production method of the transfer film of the present application is not particularly limited, and the transfer film of the present application can be obtained via the following steps: applying a composition for ultraviolet-curable resin layer on the release layer of the aforementioned support substrate, and drying and curing as necessary.

[0067] Here, the "composition for ultraviolet-curable resin layer" is a liquid containing a solvent and a solute, and refers to a material that is applied to the aforementioned support substrate, and is volatilized and removed in the process of drying the solvent, and is further cured as necessary to form an ultraviolet-curable resin layer. Here, the "kind" of the composition for ultraviolet-curable resin layer refers to a liquid that is considered to be different even if only a part of the solute that constitutes the composition for ultraviolet-curable resin layer is different. The solute contains a resin or a material that can form a resin within the application process (hereinafter, referred to as a resin precursor), a particle, and various additives such as a polymerization initiator, a curing agent, a catalyst, a leveling agent, an ultraviolet absorber, an antioxidant, and the like.

[0068] [Resin precursor]

[0069] The resin precursor can prepare the coating composition for ultraviolet-curable resin layer by itself or by being dissolved in a solvent. The resin precursor refers to a material that can cure the coating film by volatilization of the solvent and polymerization and crosslinking reaction of itself. That is, the ultraviolet-curable resin layer of the transfer film of the present application and the support substrate obtained by peeling the release film from the transfer film contain a cured product obtained by crosslinking the resin precursor.

[0070] In addition, in the aforementioned production method of the transfer film of the present application, it is preferable to use a material that can cure the coating film by polymerization of the resin precursor by active energy rays, or by a photopolymerization initiator that can be cracked by active energy rays.

[0071] Specifically, the preferred resin precursor when using ultraviolet rays as the active energy rays, and in combination with a photopolymerization initiator, is a multifunctional (meth)acrylate monomer, a (meth)acrylate oligomer, an alkoxysilane having a (meth)acrylic group, a hydrolyzate of an alkoxysilane having a (meth)acrylic group, an alkoxysilane oligomer having a (meth)acrylic group, an acrylic polymer having a (meth)acrylic group, a urethane polymer having a (meth)acrylic group, an epoxy polymer having a (meth)acrylic group, and a silicone polymer having a (meth)acrylic group.

[0072] As examples of the multifunctional acrylate monomer, a multifunctional acrylate having two or more (meth)acryloyloxy groups in one molecule and a modified polymer thereof can be used, and as specific examples, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol triacrylate, hexamethylene diisocyanate urethane polymer, and the like can be used. One or two or more of these monomers can be used.

[0073] In addition, as commercially available multifunctional acrylic compositions, Mitsubi shi Rayon Co., Ltd.; (trade name "Diabeam (registered trademark)" series, etc.), Nagase & Co., Ltd.; (trade name "DENACOL (registered trademark)" series, etc.), Shin Nakamura Chemical Co., Ltd.; (trade name "NK Ester" series, etc.), DIC Corporation; (trade name "UNIDIC (registered trademark)", etc.), Toagosei Co., Ltd.; ("Aronix (registered trademark)" series, etc.), Nippon Oil Corp.; ("BLEMMER (registered trademark)" series, etc.), Nikka Chemicals Co., Ltd.; (trade name "KAYARAD (registered trademark)" series, etc.), Kyoeisha Chemical Co., Ltd.; (trade name "Light Ester" series, etc.), and the like can be used, and these products can be utilized.

[0074] As the (meth)acrylic group-containing acrylic polymer, it is preferable to synthesize by a polymerization reaction of a polyfunctional acrylate monomer (e.g., polyol acrylate, polyester acrylate, urethane acrylate, epoxy acrylate). Among the examples of urethane-based polymers, melamine polyurethane is included. As the silicone-based polymer, it is preferable to use a co-hydrolyzate of a silane compound (e.g., tetraalkoxysilane, alkyltrialkoxysilane) and a silane coupling agent having a reactive group (e.g., epoxy group, methacrylic group). In addition, various polymers can use a polymer having no unsaturated group, a weight average molecular weight of 5,000 to 200,000, and a glass transition temperature of 20 to 200°C.

[0075] [Leveling agent]

[0076] The preferred ultraviolet-curable resin layer composition for synthesizing the ultraviolet-curable resin layer in the present application preferably contains a leveling agent. It is particularly preferable that the region B is constituted by a leveling agent, whereby it is possible to design the peeling force within an appropriate range while maintaining the function of the ultraviolet-curable resin layer. As examples of the leveling agent, acrylic copolymers or leveling agents of silicone-based, fluorine-based can be cited. Among them, particularly preferable leveling agents are those containing a hexafluoropropenyl group or a polyether group. In the case of a leveling agent containing the above-mentioned functional group, it is possible to appropriately design the coating film quality and the peeling force.

[0077] [Particle material, particle component]

[0078] The ultraviolet-curable resin layer of the transfer film of the present application can contain a particle component. Here, the particle can be any of an inorganic particle, an organic particle, and from the viewpoint of damage resistance, an inorganic particle is preferable.

[0079] The number of kinds of inorganic particles is preferably 1 or more and 20 or less. The number of kinds of inorganic particles is further preferably 1 or more and 10 or less, and particularly preferably 1 or more and 4 or less. Here, the "inorganic particle" also includes a particle on which a surface treatment has been performed. The surface treatment refers to the introduction of a compound to the surface of the particle by a chemical bond (including covalent bond, hydrogen bond, ionic bond, van der Waals bond, hydrophobic bond, etc.), adsorption (including physical adsorption, chemical adsorption).

[0080] Here, the kind of inorganic particle is determined by the kind of element constituting the inorganic particle, and in the case where a certain surface treatment is performed, it is determined according to the kind of element constituting the particle before the surface treatment. For example, in the case of titanium oxide (TiO2) and nitrogen-doped titanium oxide (TiO 2-xNx) are different kinds of inorganic particles due to the difference in the element constituting the inorganic particles. In addition, if the particles are composed of the same element, for example, only Zn and O (ZnO), even if there are a plurality of particles having different number average particle diameters, or even if the composition ratio of Zn to O is different, they are the same kind of particles. In addition, even if there are a plurality of Zn particles having different oxidation numbers, as long as the elements constituting the particles are the same (in this example, as long as the elements other than Zn are the same), they are the same kind of particles.

[0081] Here, the particles present in the composition for an ultraviolet-curable resin layer used in the present application are referred to as "particle materials", and the particles present in the aforementioned ultraviolet-curable resin layer formed by coating, drying, curing treatment, or evaporation, or the like of the aforementioned composition for an ultraviolet-curable resin layer are referred to as "particle components".

[0082] The inorganic particles are not particularly limited, and are preferably oxides, nitrides, borides, chlorides, carbonates, sulfates of metals, metalloids, can be composite oxides containing two kinds of metals, metalloids, or can have different elements introduced between the crystal lattices, or have crystal lattice points replaced by different kinds of elements, or have crystal defects introduced.

[0083] The inorganic particles are further preferably oxide particles obtained by oxidizing at least one metal, metalloid selected from the group consisting of Si, Al, Ca, Zn, Ga, Mg, Zr, Ti, In, Sb, Sn, Ba, and Ce.

[0084] Specifically, at least one metal oxide, metalloid oxide selected from the group consisting of silicon dioxide (SiO2), aluminum oxide (Al2O3), zinc oxide (ZnO), zirconium oxide (ZrO2), titanium oxide (TiO2), indium oxide (In2O3), tin oxide (SnO2), antimony oxide (Sb2O3), and indium tin oxide (In2O3).

[0085] [Solvent]

[0086] The composition for an ultraviolet-curable resin layer used in the method for manufacturing the transfer film of the present application can contain a solvent, and it is preferable to contain a solvent in order to form a coating film uniformly in the plane and to gradually change the composition in one layer. The number of kinds of the solvent is preferably 1 or more and 20 or less, more preferably 1 or more and 10 or less, further preferably 1 or more and 6 or less, and particularly preferably 1 or more and 4 or less.

[0087] Here, the "solvent" means a substance that can evaporate almost the entire amount in the drying step after coating, and is a liquid at normal temperature and normal pressure.

[0088] Here, the kind of the solvent is determined by the molecular structure of the molecule constituting the solvent. That is, the following solvents are treated as different kinds of solvents: solvents that are the same in elemental composition and the same in the kind and number of functional groups but different in the bonding relationship (structural isomers); solvents that are not the aforementioned structural isomers but do not overlap with each other in three-dimensional space regardless of the configuration (stereoisomers). For example, 2-propanol and n-propanol are treated as different solvents.

[0089] [Other components in the composition for the ultraviolet-curable resin layer]

[0090] An ultraviolet-curable polymerization initiator and a catalyst are used to promote the curing of the ultraviolet-curable resin layer. As the polymerization initiator, a substance capable of initiating or promoting the polymerization, condensation, or crosslinking reaction of the components contained in the composition for the ultraviolet-curable resin layer based on anionic, cationic, radical polymerization reaction, or the like is preferred.

[0091] Various substances can be used as the polymerization initiator, the curing agent, and the catalyst. In addition, the polymerization initiator, the curing agent, and the catalyst can be used individually, or a plurality of polymerization initiators, curing agents, and catalysts can be used simultaneously. Furthermore, an acidic catalyst and a thermal polymerization initiator can also be used in combination. As examples of the acidic catalyst, aqueous hydrochloric acid, formic acid, acetic acid, and the like can be given. As examples of the thermal polymerization initiator, peroxide compounds, azo compounds can be given. In addition, as examples of the photopolymerization initiator, alkylphenone-based compounds, sulfur-containing compounds, acyloxyphosphine-based compounds, amine-based compounds, and the like can be given. Furthermore, as examples of the crosslinking catalyst that promotes the formation reaction of urethane bonds, dibutyltin dilaurate, dibutyltin diethylhexanoate, and the like can be given.

[0092] In addition, the aforementioned composition for the ultraviolet-curable resin layer can also contain other crosslinking agents such as an alkoxyhydroxymethyl melamine or the like, an anhydride-based crosslinking agent such as 3-methyl-hexahydrophthalic anhydride or the like, an amine-based crosslinking agent such as diethylaminopropylamine or the like.

[0093] As the photopolymerization initiator, from the viewpoint of curability, an alkylphenone compound is preferred. As specific examples of the alkylphenone compound, 1-hydroxy-cyclohexyl-phenyl-ketone, 2,2-dimethoxy-1,2-diphenyl-ethane-1-ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-ketone, 2-benzyl-2-dimethylamino-1-(4-phenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-phenyl)-1-butanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 1-cyclohexyl-phenyl ketone, 2-methyl-1-phenylpropane-1-ketone, 1-[4-(2-ethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-ketone, bis(2-phenyl-2-oxoacetate)oxybisethylene, and a substance obtained by polymerizing these materials to a high molecular weight, and the like can be given.

[0094] If it is within a range that does not hinder the effects of the present application, an ultraviolet absorber, a lubricant, an antistatic agent, or the like can be added to the ultraviolet curable resin layer composition used to form the ultraviolet curable resin layer. Thus, the ultraviolet curable resin layer can contain an ultraviolet absorber, a lubricant, an antistatic agent, or the like. As specific examples of the ultraviolet absorber, benzophenone-based, benzotriazole-based, oxanilide-based, triazine-based, and hindered amine-based ultraviolet absorbers can be given. As examples of the antistatic agent, metal salts such as lithium salts, sodium salts, potassium salts, rubidium salts, cesium salts, magnesium salts, and calcium salts can be given.

[0095] It is preferred that the coating layer formed on the release layer be dried and cured in the above-described manner, thereby forming the ultraviolet curable resin layer.

[0096] [Uses]

[0097] The transfer film of the present application exhibits damage resistance, followability to surface shapes, and the like, and can be suitably used for surface protection of a molded body composed of, for example, plastic or metal. Furthermore, the support substrate obtained by peeling the support substrate and the release layer from the transfer film of the present application can be suitably used, for example, as a protective film for a molded body.

[0098] Note that the method for manufacturing the support substrate in the present application is not particularly limited, and for example, the support substrate in the present application can be manufactured by peeling only the ultraviolet curable resin layer from the transfer film of the present application after the transfer film is manufactured.

[0099] As described above, the support substrate in the present application can be suitably used, for example, as a protective film for a molded body, in terms of the use thereof.

[0100] Example

[0101] [Resin composition for release layer]

[0102] The following materials were mixed and diluted with a methyl ethyl ketone / isopropyl alcohol mixed solvent (mass mixing ratio 50 / 50) to obtain a resin composition for a release layer having a solid content concentration of 5 mass%.

[0103] • Monoterminal methanol-modified reactive silicone oil

[0104] (X-22-170DX Shin-Etsu Chemical Co., Ltd. solid content concentration 100 mass%) : 1 mass part

[0105] • Diterminal polyether-modified reactive silicone oil

[0106] (X-22-4952 Shin-Etsu Chemical Co., Ltd. solid content concentration 100 mass%) : 5 mass parts

[0107] • Acrylic-modified alkyd resin

[0108] (Hariphthal KV-905 Harima Chemicals Group, Inc. solid content concentration 53 mass%) : 100 mass parts

[0109] • Isobutyl alcohol-modified melamine resin

[0110] (Melan 2650L Hitachi Chemical Co., Ltd. solid content concentration 60 mass%) : 20 mass parts

[0111] • p-Toluenesulfonic acid: 5 mass parts.

[0112] [Production of composition for ultraviolet-curable resin layer]

[0113] [Composition for ultraviolet-curable resin layer]

[0114] The following materials were mixed and diluted with methyl ethyl ketone to obtain a composition for an ultraviolet-curable resin layer having a solid content concentration of 20 mass%.

[0115] • Resin precursor A: butyl acetate / ethyl acetate solution of polymeric acrylate resin 190 mass parts

[0116] ("UNIDIC" V-6850 DIC Corporation solid content concentration 50 mass%)

[0117] • Resin precursor B: urethane acrylate oligomer

[0118] ("Irgacure" 819, manufactured by Ciba Specialty Chemicals Inc., solid content concentration 100 mass %): 1 mass part

[0119] • leveling agent

[0120] (LINC-3A Kyoeisha Chemical Co., Ltd., solid content concentration 100 mass %): 1 mass part

[0121] • α-hydroxyacetophenone type photopolymerization initiator: 3 mass parts

[0122] ("Omnirad (registered trademark)" 184 IG, manufactured by IGM Resins).

[0123] [Manufacture of support substrate with release layer]

[0124] Using the aforementioned release layer composition and support substrate, a release layer was formed by the following method, and a support substrate with release layer was manufactured.

[0125] [Method for forming release layer]

[0126] Using a coating device having a small-diameter gravure coater, the release layer composition was coated on a polyester film (product name "Lumirror (registered trademark)" R75X, manufactured by Toray Industries, Inc., thickness 38 μm) in such a manner that the gravure line number, peripheral speed, and solid content concentration were adjusted to become the release layer thicknesses described in Table 1, and then dried and cured by keeping at a hot air temperature of 120°C for 30 seconds, thereby obtaining a support substrate with release layer.

[0127] [Manufacture of transfer film]

[0128] Using the aforementioned ultraviolet-curable resin layer composition and support substrate with release layer, an ultraviolet-curable resin layer was formed, and a transfer film was manufactured. The ultraviolet-curable resin layer composition used and the method for forming the ultraviolet-curable resin layer, and the combination of the ultraviolet-curable resin layer thicknesses are described in Table 1.

[0129] [Method for forming ultraviolet-curable resin layer]

[0130] Using a continuous coating device having a single-layer slit die coater, the aforementioned ultraviolet-curable resin layer composition was coated on the aforementioned support substrate with release layer after adjusting the discharge flow rate from the slit in such a manner that the ultraviolet-curable resin layer thicknesses described in Table 1 were obtained, and then dried by keeping at a hot air temperature of 80°C for 30 seconds, and then cured by irradiating a high-pressure mercury lamp under conditions in which the oxygen partial pressure was 0.1 vol% or less, the irradiation output power was 400 W / cm 2 , and the irradiation intensity was 120 mJ / cm 2 , thereby forming an ultraviolet-curable resin layer.

[0131] The transfer films of Examples 1 to 6 and Comparative Examples 1 to 6 were produced by the above method. The production method of the transfer film, and the thickness of the release layer and the ultraviolet-curable resin layer corresponding to each example and comparative example are described in Table 1.

[0132] [Table 1]

[0133]

[0134] [Physical property evaluation of transfer film and support substrate]

[0135] For the transfer film, the physical property evaluation shown below was carried out, and the results obtained were summarized in Table 1. For the measurement, except for the cases specifically described, 3 measurements were carried out for one sample at different sites in each example and comparative example, and the average value thereof was used.

[0136] [Measurement method]

[0137] [FT-IR analysis method]

[0138] The FT-IR analysis was carried out by using a Fourier transform infrared spectrophotometer (manufactured by Bruker Corporation, trade name "FT-IR TENSOR II") as a measuring device, and using the following conditions.

[0139] • Light source: silicon-carbon rod (SiC)

[0140] • Detector: DLaTGS

[0141] • Resolution: 4 cm -1

[0142] • Measurement range: 400 to 4000 cm -1 .

[0143] [Measurement of interlayer peeling strength between ultraviolet-curable resin layer and release layer of transfer film]

[0144] For the transfer film, one release film of an adhesive film (Panac Co., Ltd., PanaClean PD-S1 25 μm product) was attached to the surface of the ultraviolet-curable resin layer of the transfer film in such a manner that no bubbles entered, and then the release film of the adhesive film was peeled off, and was attached to a PET film (188 μm, manufactured by Toyobo Co., Ltd., "Lumirror (registered trademark)" T60).

[0145] After cutting the above-described laminated film into a width of 25 mm, the interlayer peeling strength (N / 25 mm) between the ultraviolet-curable resin layer and the release layer of the transfer film was measured by using a universal tensile tester (Intesco Co., Ltd., model: 200X) to perform 180-degree peeling at 300 mm / min test speed.

[0146] In addition, after cutting the laminated film into 25 mm, the interlayer peeling strength (N / 25 mm) between the ultraviolet-curable resin layer and the release layer of the transfer film after heating was measured by using the same method as described above after performing heating treatment at 150°C for 5 minutes using a constant temperature bath.

[0147] [Evaluation of the haze of the adherend after peeling]

[0148] With respect to the transfer film produced in the examples and comparative examples, heating treatment was performed at 150°C for 5 minutes using a constant temperature bath. Then, one of the film-removing surfaces of the adhesive film (Panac Co., Ltd., PanaClean PD-S125 μm product) was attached to the surface of the ultraviolet-curable resin layer of the transfer film in such a manner that no bubbles entered, and then the film of the adhesive film was removed, and the transfer film was attached to a glass having a haze value of 0.1%, and the transfer film was removed as the adherend after peeling. Then, with respect to the adherend after peeling, the haze was measured by using a haze meter (HMG-2DP) manufactured by Suga test Instruments, in which the peeled surface of the two surfaces of the test piece was disposed in front of the light source.

[0149] [Evaluation of the thickness of the ultraviolet-curable resin layer]

[0150] The cross section of the transfer film was cut into an ultrathin section, and observation was performed by TEM (transmission electron microscope) at an acceleration voltage of 100 kV (observation was performed at a magnification of 1 to 300,000), and the thickness of the ultraviolet-curable resin layer was measured from the cross-sectional photograph. Note that the measurement site of the thickness was a portion in which no protrusion was present on the surface. The measurement of the thickness was performed at five sites, and the average value thereof was used as the thickness of the ultraviolet-curable resin layer.

[0151] Explanation of Reference Numerals

[0152] 1 Support base material

[0153] 2 Release layer

[0154] 3 Ultraviolet-curable resin layer

[0155] 4 Transfer film

Claims

1. A transfer film comprising a release layer and an ultraviolet curable resin layer in this order on at least one surface of a supporting substrate, wherein: The interlayer peeling strength between the ultraviolet curable resin layer and the release layer of the transfer film after heating at 150° C. is 0.04 N / 25 mm to 0.12 N / 25 mm, and the thickness of the ultraviolet curable resin layer is 0.5 μm to 2.5 μm.

2. The transfer film according to claim 1, wherein The thickness of the release layer is 350 nm to 500 nm.

3. The transfer film according to claim 1, wherein The interlayer peeling strength between the ultraviolet curable resin layer and the release layer of the transfer film before heating at 150° C. and after peeling is 0.04 N / 25 mm or more.

4. The transfer film according to claim 1, wherein The adherend had a haze of 0.50% or less after being heated and peeled at 150°C.

5. The method for producing a transfer film according to claim 1, wherein A release layer is formed on a supporting substrate using a release layer resin composition, wherein the release layer resin composition has a relative humidity of 1118 cm-1 as measured by FT-IR. -1 The peak intensity at 1.5 times or more the peak intensity of the resin composition for a release layer after being left for 0 hours after stirring is obtained.

Images