Low-friction film, method for manufacturing the same, molded body, and method for improving finger slidability

Abstract

A film is produced in which at least one surface has a peakiness (Rku) of 2 or more and a maximum cross-sectional height (Rt) of 1 μm or more. The dynamic friction coefficient of the surface can be 0.25 or less, and the relative dynamic friction coefficient can be 0.3 or less. The film includes a low-friction layer formed from a cured product of a curable composition containing a curable resin, and the surface of the low-friction layer can have the Rku and Rt in the above ranges. The curable resin can contain at least one selected from a (meth)acrylic polymer having a polymerizable group, a urethane (meth)acrylate, and a silicone (meth)acrylate. The curable composition can further contain a cellulose ester. The curable composition can not contain microparticles. The film can reduce the dynamic friction coefficient even if the surface is formed from a variety of materials.

Description

[0001] This application is a divisional application of an application with the application date of October 11, 2018, the application number of 201880052370.6, and the invention name of "Low Friction Film and Manufacturing Method Thereof, Shaped Body, and Finger Slippage Improvement Method". TECHNICAL FIELD

[0002] The present application relates to a low friction film for covering the surface of a touch panel display, a frame of an electric home appliance, a building material, and the like, a manufacturing method thereof, a shaped body, and a method for improving the slippage (particularly, finger slippage) of the film. BACKGROUND

[0003] For the surface of a touch panel display in a personal computer (PC), a smart phone, and the like, a frame of an electric home appliance, a building material, and the like, in order to prevent scratches and improve the sense of touch, a method of pasting a hard coat film as a surface protective layer or a cover layer, and a method of performing a hard coat treatment are known. The hard coat film and the hard coat layer are required to have good slippage when touched by a hand, and as a method for improving the slippage, a hard coat treatment containing a silicone compound and a fluorine compound has been generally performed to improve the slippage.

[0004] Japanese Patent Application Publication No. 2007-264281 (Patent Literature 1) discloses a hard coat layer for an optical laminate, which is formed by containing a silicon compound, a fluorine compound, or a mixture thereof as an anti-fouling agent and / or a slippage imparting agent, and in the case where XPS analysis is performed on the surface of the hard coat layer, the presence ratio of silicon atoms is 10% or more, and / or the presence ratio of fluorine atoms is 20% or more.

[0005] In addition, WO2008 / 038714 (Patent Literature 2) discloses an optical functional film having a substrate, an optical functional layer formed on the substrate, and an anti-fouling layer formed on the optical functional layer, the surface of the anti-fouling layer having an element ratio of silicon element (Si) to carbon element (C) of Si / C of 0.25 to 1, and fluorine element (F) to carbon element (C) of F / C of 0.1 to 1, a liquid paraffin contact angle and a roll-off angle of 65° or more and 15° or less, a black marker ink contact angle and a roll-off angle of 35° or more and 15° or less, and a dynamic friction coefficient of less than 0.15.

[0006] However, for these hard coat layers and anti-fouling layers, although the silicone compound and the fluorine compound can be used to reduce the friction coefficient of the surface, it is not sufficient, and the finger slippage can be significantly different due to the slight difference in the surface structure. In addition, since the surface is water repellent, the use is limited, and since the surface is leveled by wet coating, it is difficult to control the surface shape using the convection phenomenon.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-264281 (Claim 1)

[0010] Patent Document 2: WO 2008 / 038714 (Claim 1) SUMMARY

[0011] PROBLEMS TO BE SOLVED BY THE INVENTION

[0012] Therefore, an object of the present application is to provide a low-friction film which can reduce the dynamic friction coefficient even if the surface is formed of a variety of materials, a molded body and a manufacturing method thereof, and a method for improving the finger sliding property of the film.

[0013] In addition, another object of the present application is to provide a low-friction film which can improve the sliding property (particularly, the finger sliding property) without using a large amount of silicone compounds and fluorine compounds, a manufacturing method thereof, a molded body, and a method for improving the sliding property (particularly, the finger sliding property) of the film.

[0014] METHOD FOR SOLVING THE PROBLEM

[0015] The present inventors have conducted intensive studies in order to solve the above problem, and as a result, have found that by adjusting the kurtosis (Rku) and the maximum cross-sectional height (Rt) of the surface of the film, the dynamic friction coefficient can be reduced even if the surface is formed of a variety of materials, thereby completing the present application.

[0016] That is, at least one surface of the film (low-friction film) of the present application has an Rku of 2 or more and an Rt of 1 μm or more. The dynamic friction coefficient of the above surface can be 0.25 or less, and the relative dynamic friction coefficient can be 0.3 or less. The above film is formed of a cured product of a curable composition containing a curable resin, and includes a low-friction layer disposed in the top layer, and the surface of the low-friction layer can have an Rku of 2 or more and an Rt of 1 μm or more. The above curable resin can contain at least one selected from the group consisting of (meth)acrylic polymers having a polymerizable group, urethane (meth)acrylates, and silicone (meth)acrylates. The above curable composition can further contain a cellulose ester. The above curable composition can not contain microparticles. The above low-friction film can have a low-friction layer laminated on a base layer formed of a transparent resin. The above film can be such that the presence ratio of silicon atoms on the surface is less than 10%, and the presence ratio of fluorine atoms on the surface is less than 20%.

[0017] The present application also includes a method for manufacturing the above-mentioned film, which includes a curing step of curing a curable composition containing a curable resin. In addition, the present application also includes a molded body provided with the above-mentioned film on a surface. The molded body can be a touch panel display. Furthermore, the present application also includes a method for improving the finger sliding property of a film by adjusting the surface of at least one side of the film to have a kurtosis (Rku) of 2 or more and a maximum cross-sectional height (Rt) of 1 μm or more.

[0018] Effects of the Invention

[0019] In the present application, since the Rku and Rt of the concave-convex structure of the surface of the film are adjusted to a specific range, the dynamic friction coefficient can be reduced even if the surface of the film is formed of a variety of materials. Therefore, the sliding property (particularly, the finger sliding property or the touch comfort) of the film can be improved without using a large amount of silicone compounds or fluorine compounds. DETAILED DESCRIPTION

[0020] [Low Friction Film]

[0021] The film (low friction film) of the present application has an Rku (sharpness) of 2 or more on at least one surface and an Rt of 1 μm or more on the above-mentioned surface, and therefore, a convex portion having a large sharpness and height difference is formed on the surface. Therefore, it can be inferred that, in the case where the surface of the low friction film of the present application is contacted with a contact body such as a finger, the dynamic friction coefficient can be reduced because the contact area is small. The surface having a concave-convex structure in which the Rku and Rt are adjusted to the above-mentioned range can be formed on both surfaces, but generally, it is formed on one surface which becomes the side contacted with a finger in most cases.

[0022] The Rku (kurtosis) of the above-mentioned surface can be 2 or more (for example, 2 to 100), for example, 2.5 to 80 (for example, 3 to 50), preferably 3.2 to 30 (for example, 3.3 to 20), further preferably about 3.5 to 10 (particularly, 4 to 5). If the Rku is too small, the dynamic friction coefficient of the surface cannot be reduced, and the finger sliding property cannot be improved.

[0023] The Rt (maximum cross-sectional height) of the above-mentioned surface can be 1 μm or more (for example, 1 to 30 μm), for example, 1.5 to 20 μm (for example, 2 to 15 μm), preferably 2 to 10 μm (for example, 2.5 to 8 μm), further preferably about 3 to 5 μm (particularly, 3.5 to 4.5 μm). If the Rt is too small, the dynamic friction coefficient of the surface cannot be reduced, and the finger sliding property cannot be improved.

[0024] Note that, in the present specification and claims, the Rku and Rt can be measured based on JIS B0601 using an optical surface roughness meter or the like, and in detail, can be measured by the method described in the Examples described later.

[0025] The surface described above has a concavo-convex structure in which Rku and Rt are adjusted to the ranges described above, and therefore the kinetic friction coefficient (μk) is low. The kinetic friction coefficient of the surface can be 0.25 or less, for example, 0.01 to 0.23, preferably 0.03 to 0.2, further preferably 0.05 to 0.15 (particularly 0.08 to 0.12) or so. In addition, the relative kinetic friction coefficient can be 0.3 or less, for example, 0.01 to 0.29, preferably 0.04 to 0.25, further preferably 0.06 to 0.19 (particularly 0.1 to 0.15) or so.

[0026] Note that in the present specification and claims, the kinetic friction force can be measured using a kinetic-static friction tester, and in detail, can be measured by the method described in the Examples below. On the other hand, the relative kinetic friction coefficient is a value obtained by dividing the kinetic friction force of the film measured under the same load by the kinetic friction force of glass measured as a test object, and in detail, can be measured by the method described in the Examples below. The friction properties of the film are evaluated as a relative value to the kinetic friction force of a stable glass surface, and therefore are reliable evaluations in which errors caused by changes in the artificial skin over time are mitigated.

[0027] The low-friction film of the present application only needs to have a concavo-convex structure in which Rku and Rt of at least one surface are adjusted to the ranges described above, and the material and structure of the film are not particularly limited.

[0028] Regarding the material, the low-friction film of the present application can reduce the kinetic friction coefficient even if it does not contain a large amount of a silicone compound and a fluorine compound, because Rku and Rt of the surface are adjusted to the ranges described above. Therefore, the presence ratio of silicon atoms in the surface of the low-friction film (particularly the surface having Rku and Rt in the ranges described above) can be less than 10%, and can be preferably 5% or less, further preferably 1% or less. In addition, the presence ratio of fluorine atoms in the surface of the low-friction film (particularly the surface having Rku and Rt in the ranges described above) can be less than 20%, and can be preferably 10% or less, further preferably 1% or less. Note that in the present specification and claims, the presence ratios of silicon atoms and fluorine atoms can be measured by a conventional method using an X-ray photoelectron spectrometer (XPS).

[0029] Regarding the structure, the low-friction film of the present application can be, for example, a single-layer film in which Rku and Rt of at least one surface are adjusted to the ranges described above, or can be a laminate including a low-friction layer in which Rku and Rt of the surface are adjusted to the ranges described above.

[0030] (Single-layer film and low-friction layer)

[0031] The material of the single layer film and the low friction layer is not limited by the above, and can be selected from various organic materials (thermoplastic resins, thermosetting resins, photocurable resins, etc.), inorganic materials (glass, ceramics, metals, etc.), but from the viewpoint of productivity, etc., the cured product of a curable composition containing a curable resin is preferred.

[0032] The curable resin can be any of a thermosetting resin, a photocurable resin, but from the viewpoint of productivity, etc., a (meth)acrylic photocurable resin is often used. In addition, the (meth)acrylic resin also has excellent transparency, and thus can be suitably used as a protective film for optical applications such as a touch panel display.

[0033] As the (meth)acrylic photocurable resin, for example, a multifunctional (meth)acrylate [for example, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc. having about 2 to 8 polymerizable groups], an epoxy (meth)acrylate [a multifunctional epoxy (meth)acrylate having 2 or more (meth)acryloyl groups], a polyester (meth)acrylate [a multifunctional polyester (meth)acrylate having 2 or more (meth)acryloyl groups], a urethane (meth)acrylate [a multifunctional urethane (meth)acrylate having 2 or more (meth)acryloyl groups], a silicone (meth)acrylate [a multifunctional silicone (meth)acrylate having 2 or more (meth)acryloyl groups], a (meth)acrylic polymer having a polymerizable group, etc. can be exemplified. These curable resins can be used alone or in combination of two or more.

[0034] Among these curable resins, a urethane (meth)acrylate, a silicone (meth)acrylate, and a (meth)acrylic polymer having a polymerizable group are preferred, and a (meth)acrylic polymer having a polymerizable group is particularly preferred. The (meth)acrylic polymer having a polymerizable group can be a polymer in which a polymerizable unsaturated group is introduced to a part of carboxyl groups of a (meth)acrylic polymer, for example, a (meth)acrylic polymer in which a part of carboxyl groups of a (meth)acrylate-meth)acrylate copolymer is reacted with an epoxy group of an epoxy group-containing (meth)acrylate (for example, 3,4-epoxycyclohexenylmethyl acrylate, etc.) to introduce a polymerizable group (a photopolymerizable unsaturated group) to a side chain (manufactured by Daicel Ornex Corporation, "CYCLOMER P").

[0035] The (meth)acrylic polymer having a polymerizable group is preferably combined with a urethane (meth)acrylate and / or a silicone (meth)acrylate, and particularly preferably combined with a urethane (meth)acrylate and a silicone (meth)acrylate.

[0036] In the case where the (meth)acrylic polymer having a polymerizable group is combined with the urethane (meth)acrylate and / or silicone (meth)acrylate, the proportion of the urethane (meth)acrylate is, for example, 10 to 300 parts by weight, preferably 100 to 200 parts by weight, further preferably about 120 to 180 parts by weight, relative to 100 parts by weight of the (meth)acrylic polymer having a polymerizable group. The proportion of the silicone (meth)acrylate is, for example, 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, further preferably about 1 to 3 parts by weight, relative to 100 parts by weight of the (meth)acrylic polymer having a polymerizable group.

[0037] The curable composition can further contain a cellulose ester in addition to the above-described curable resin. As the cellulose ester, there can be mentioned, for example, cellulose acetate, cellulose triacetate, and the like; cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, and the like; and cellulose C 2-6 These cellulose esters can be used alone or in combination of two or more. Among these, cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, and the like are preferred, and cellulose acetate C 2-4 propionate, and the like are particularly preferred. The proportion of the cellulose ester is, for example, 0.1 to 30 parts by weight, preferably 0.5 to 20 parts by weight, further preferably about 1 to 10 parts by weight (particularly 2 to 5 parts by weight), relative to 100 parts by weight of the curable resin. 3-4

[0038] The curable composition can further contain a fine particle in addition to the above-described curable resin. As the fine particle, there can be mentioned, for example, inorganic fine particles such as silica particles, titanium dioxide particles, zirconium oxide particles, aluminum oxide particles, and the like; copolymer particles of a (meth)acrylic monomer and a styrene monomer; crosslinked (meth)acrylic polymer particles; crosslinked styrene resin particles; and the like. These fine particles can be used alone or in combination of two or more. Among these, crosslinked (meth)acrylic polymer particles and the like are often used. The average particle diameter of the fine particle is, for example, 1 to 30 μm, preferably 10 to 30 μm, further preferably about 15 to 25 μm. The proportion of the fine particle is, for example, 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, further preferably about 0.3 to 3 parts by weight (particularly 0.4 to 1 part by weight), relative to 100 parts by weight of the curable resin.

[0039] ​Note that, in the present application, in the case where the curable resin [particularly, a (meth)acrylic polymer having a polymerizable group, a combination with a urethane (meth)acrylate and / or a silicone (meth)acrylate] is combined with the cellulose ester, a surface having the Rku and the Rt in the above-mentioned ranges and a low dynamic friction coefficient can be formed without using microparticles.

[0040] The curable composition can contain, in addition to the above-mentioned curable resin, usual additives such as a polymerization initiator, a stabilizer (an antioxidant, an ultraviolet absorber, etc.), a surfactant, a water-soluble polymer, a filler, a crosslinking agent, a coupling agent, a coloring agent, a flame retardant, a lubricant, a wax, a preservative, a viscosity modifier, a thickening agent, a leveling agent, an antifoaming agent, etc. These additives can be used alone or in combination of two or more.

[0041] In the case where the curable composition is a photocurable composition, the photocurable composition can contain a photopolymerization initiator as the polymerization initiator. As the photopolymerization initiator, for example, acetophenone-based or propiophenone-based compounds, benzil-based compounds, benzoin-based compounds, benzophenone-based compounds, thioxanthone-based compounds, acylphosphine oxide-based compounds, etc. can be exemplified. The photopolymerization initiator can also contain a usual photosensitizer, a photopolymerization accelerator (for example, tertiary amine-based compounds, etc.). The proportion of the photopolymerization initiator is, for example, 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, and further preferably about 1 to 3 parts by weight, relative to 100 parts by weight of the photocurable resin.

[0042] The curable composition before curing can further contain a solvent. As the solvent, for example, ketone-based compounds, ether-based compounds, hydrocarbon-based compounds, ester-based compounds, water, alcohol-based compounds, cellulose acetate-based compounds, acetic acid cellulose acetate-based compounds, sulfoxide-based compounds, amide-based compounds, etc. can be exemplified. In addition, the solvent can also be a mixed solvent. Of these solvents, ketone-based compounds (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.) are preferred, and a mixed solvent of ketone-based compounds and alcohol-based compounds (ethanol, isopropyl alcohol, butanol, cyclohexanol, etc.) is particularly preferred. The proportion of the solvent is, for example, 30 to 300 parts by weight, preferably 50 to 250 parts by weight, and further preferably about 100 to 200 parts by weight, relative to 100 parts by weight of the curable resin.

[0043] The average thickness of the single layer film and the low friction layer is, for example, 1 to 30 μm, preferably 3 to 20 μm, and further preferably about 5 to 15 μm (particularly, 8 to 10 μm), respectively. Note that, in the present specification and the claims, the average thickness of the single layer film and the low friction layer can be measured by the method described in the Examples below.

[0044] (Laminate)

[0045] In the case where the low-friction film is a laminate, the low-friction layer described above can be provided on the most surface, and the laminated structure is not particularly limited, but from the viewpoint of productivity, handleability, and the like, a structure in which the low-friction layer is laminated on the substrate layer (a laminate of the substrate layer and the low-friction layer laminated on one surface of the substrate layer) is preferred.

[0046] The material of the substrate layer is not particularly limited, and can be selected from various organic materials (thermoplastic resins, thermosetting resins, photocurable resins, and the like), inorganic materials (glass, ceramics, metals, and the like), but in the case of use as a protective film for optical use such as a touch panel display, a transparent material is preferred.

[0047] As the transparent material, for example, inorganic materials such as glass; organic materials such as cellulose esters, polyesters, polyamides, polyimides, polycarbonates, (meth)acrylic polymers, and the like can be exemplified. Among these, cellulose esters, polyesters, and the like are often used.

[0048] As the cellulose ester, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, and the like can be exemplified. As the polyesters, polyalkylene arylate such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and the like can be exemplified. 3-4

[0049] Among these, from the viewpoint of excellent balance of mechanical properties, transparency, and the like, polyalkylene arylate such as PET, PEN, and the like is preferred. 8-12 2-4 alkylene arylate.

[0050] The substrate layer formed of the polyester can be a uniaxially or biaxially stretched film, but from the viewpoint of excellent low birefringence and optical anisotropy, it can also be an unstretched film.

[0051] The substrate layer can be subjected to surface treatment (for example, corona discharge treatment, flame treatment, plasma treatment, ozone or ultraviolet irradiation treatment, and the like), and can have an easy-adhesion layer.

[0052] The average thickness of the substrate layer can be 10 μm or more, for example, 12 to 500 μm, preferably 20 to 300 μm, and further preferably about 30 to 200 μm.

[0053] (Adhesive layer)

[0054] The low-friction film of the present application can also be provided with an adhesive layer on at least a part of the back surface (the back surface of the low-friction film in a single layer film, the surface of the substrate layer, and the like) of the surface on which the concave-convex structure having Rku and Rt in the above range is formed. The low-friction film described above on which the adhesive layer is formed on the back surface can also be used as a protective film in a touch panel display such as a smart phone, a tablet PC, and the like. ​​

[0055] The adhesive layer is formed from a conventional transparent adhesive. As the adhesive, for example, a rubber-based adhesive, an acrylic adhesive, an olefin-based adhesive (a modified olefin-based adhesive, etc.), a silicone-based adhesive, etc. can be exemplified. These adhesives can be used alone or in combination of two or more. Among these adhesives, from the aspects of optical properties, reworkability, etc., a silicone-based adhesive is preferred.

[0056] The average thickness of the adhesive layer is, for example, 1 to 150 μm, preferably 10 to 100 μm, further preferably about 20 to 70 μm (particularly 25 to 50 μm).

[0057] The adhesive layer can be formed on the entire back surface, or on a part (for example, the peripheral edge portion) of the back surface. Further, in the case of being formed on the peripheral edge portion, for the purpose of improving the handleability for the bonding, a frame-shaped member (for example, a plastic sheet is laminated on the peripheral edge portion) can be formed on the peripheral edge portion of the low-friction film, and the adhesive layer can be formed on the frame-shaped member.

[0058] [Method for manufacturing low-friction film]

[0059] The method for manufacturing the low-friction film of the present application is not particularly limited as long as it is a method that can form the concavo-convex structure on the surface, the Rku and the Rt of which are adjusted to the above-described ranges, and can be appropriately selected depending on the material of the low-friction film. As a specific manufacturing method, for example, a method including a curing step of curing a curable composition containing a curable resin (for example, a method of curing a curable composition containing a fine particle by protruding the fine particle, a method of curing a curable composition containing a resin component capable of undergoing phase separation after the above-described resin component in the curable composition undergoes phase separation, etc.), a method of transferring using a mold having a concavo-convex structure on the surface, a method of forming a concavo-convex structure by cutting processing (for example, cutting processing using a laser, etc.), a method of forming a concavo-convex structure by polishing (for example, a sandblasting method, a bead blasting method, etc.), a method of forming a concavo-convex structure by etching, etc. can be exemplified.

[0060] Among these methods, from the aspect that the low-friction film having the concavo-convex structure on the surface, the Rku and the Rt of which are adjusted to the above-described ranges, can be manufactured with high productivity, a method including a curing step of curing a curable composition containing a curable resin is preferred, for example, a method in which a liquid curable composition is applied on a support (the above-described base material layer constituting the low-friction film in the case of a laminate) and is dried and then cured can be exemplified.

[0061] As the coating method, there can be mentioned, for example, roll coating, air knife coating, blade coating, bar coating, reverse coating, wire bar coating, gravure coating, dip squeeze coating, die coating, gravure coating, microgravure coating, screen coating and the like, dipping, spraying, rotation and the like. Of these, the wire bar coating, gravure coating and the like are generally used. Note that the coating liquid can be coated plural times as needed.

[0062] The drying temperature is, for example, 30 to 120°C, preferably 50 to 110°C, further preferably 60 to 100°C (particularly 70 to 90°C) or so. The drying time is, for example, 0.1 to 10 minutes, preferably 0.3 to 5 minutes, further preferably 0.5 to 3 minutes or so.

[0063] The curing method is a method of applying active light (ultraviolet light, electron beam and the like), heat and the like according to the type of the curable resin, and in the case of a photocurable resin, the light irradiation can be selected according to the type of the photocurable resin and the like, and ultraviolet light, electron beam and the like can be generally used. The exposure source is generally an ultraviolet irradiation device.

[0064] As the light source, for example, in the case of ultraviolet light, a Deep UV lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a halogen lamp, a laser light source (helium-cadmium laser, excimer laser and the like) and the like can be used. The amount of light irradiation (irradiation energy) differs according to the thickness of the coating film, and is, for example, 10 to 10,000 mJ / cm 2 , preferably 20 to 5,000 mJ / cm 2 , further preferably 30 to 3,000 mJ / cm 2 or so. The light irradiation can be performed in an atmosphere of an unreactive gas as needed.

[0065] In the method of curing such a curable composition, as the method of forming the concavo-convex structure in which Rkuand Rtare adjusted to the above range, there can be mentioned, for example, a method of incorporating microparticles in the above curable composition, protruding the microparticles and curing (a method using microparticles); a method of incorporating a resin component that can undergo phase separation in the above curable composition, allowing the resin component to undergo phase separation and then curing (a method using phase separation); and the like.

[0066] In the method using microparticles, by curing the curable composition in a state in which the microparticles protrude from the surface, a concavo-convex structure can be formed on the surface.

[0067] In the method utilizing phase separation, in the process of evaporating or removing the solvent from the liquid phase of the composition containing the resin component in which phase separation can occur and the solvent by drying or the like, phase separation caused by spinodal decomposition (wet spinodal decomposition) can occur along with concentration of the composition, and thus a surface concave-convex structure (phase separation structure) in which the distance between phases is relatively ordered can be formed. As the method utilizing phase separation, for example, the methods described in Japanese Patent Application Publication No. 2007-187746, Japanese Patent Application Publication No. 2008-225195, Japanese Patent Application Publication No. 2009-267775, Japanese Patent Application Publication No. 2011-175601, Japanese Patent Application Publication No. 2014-85371, and the like can be used. As the combination of the resin component in which phase separation can occur, a combination of a (meth)acrylic polymer having a polymerizable group, a urethane (meth)acrylate, a silicone (meth)acrylate, and a cellulose ester is preferable.

[0068] Examples

[0069] Hereinafter, the present application will be more specifically described by examples, but the present application is not limited to these examples. The raw materials used in the examples and comparative examples are described below, and the obtained low friction film was evaluated by the following method.

[0070] [Raw materials]

[0071] Acrylic polymer having a polymerizable group A: "KRM8713B" manufactured by Daicel Ornex Co., Ltd.

[0072] Acrylic polymer having a polymerizable group B: "CYCLOMER P" manufactured by Daicel Ornex Co., Ltd.

[0073] Acrylic polymer: "8KX-078" manufactured by Taisei Fine Chemical Co., Ltd.

[0074] Urethane-modified copolymerized polyester resin: "Byron (registered trademark) UR-3200" manufactured by Toyobo Co., Ltd.

[0075] Cellulose acetate propionate: "CAP-482-20" manufactured by Eastman Co., acetylation degree = 2.5%, propionylation degree = 46%, polystyrene-equivalent number average molecular weight = 75,000

[0076] Urethane acrylate: "UA-53H" manufactured by Shin-Nakamura Chemical Co., Ltd.

[0077] Silicone acrylate: "EBECRYL 1360" manufactured by Daicel Ornex Co., Ltd.

[0078] PMMA Beads A: "SSX-115" manufactured by Sekisui Chemical Co., Ltd., average particle diameter 15 μm PMMA Beads B: "SSX-110" manufactured by Sekisui Chemical Co., Ltd., average particle diameter 10 μm

[0079] Acrylic UV-curable compound containing nanosilica: "Z7501" manufactured by JSR Corporation

[0080] Photoinitiator A: "Irgacure 184" manufactured by BASF Japan Ltd.

[0081] Photoinitiator B: "Irgacure 907" manufactured by BASF Japan Ltd.

[0082] Polyethylene terephthalate (PET) film: "Diafoil" manufactured by Mitsubishi Resin Co., Ltd.

[0083] [Thickness of low-friction layer]

[0084] The average value was calculated by measuring 10 arbitrary sites using an optical film thickness meter.

[0085] [Surface shape]

[0086] The maximum cross-sectional height (Rt) and the sharpness of the concave-convex (Rku) were measured based on JIS B0601 using an optical surface roughness meter ("VertScan R5500G" manufactured by Hitachi High-Technologies Corporation) under conditions of a scanning range of 2.5 mm square and a number of scans of 2.

[0087] [Dynamic friction coefficient and relative dynamic friction coefficient]

[0088] The dynamic friction force (dynamic friction coefficient) was measured under measurement conditions (load 20 g weight, speed 25 mm / sec) using a dynamic static friction tester ("Handy Rub Tester TL201Ts" manufactured by Trinity Lab Co., Ltd.). As the contactor, a contactor in which artificial skin ("BIOSKIN" manufactured by Beaulax Co., Ltd.) was attached to a 5 mm-thick sponge sheet ("N-1 for gap" manufactured by Cemedine Co., Ltd.) was used. The relative dynamic friction coefficient was obtained by dividing the dynamic friction force of the film as the measurement object by the dynamic friction force measured using glass (soda lime glass) as the test object.

[0089] [Finger sliding property]

[0090] Evaluation of finger sliding property was performed as follows: a sample obtained by adhering the substrate layer side of the obtained low friction film using an optical adhesive (OCA) film of 25 μm thickness to an acrylic plate was used, and the index finger was slid on the film (surface of the low friction layer) using the feeling of operating a smart phone, whereby evaluation of finger sliding property was performed. For 20 subjects, the evaluation results were listened to according to the following 5-grade criteria.

[0091] 1 point: the finger was difficult to slide, and the operation was stuck in the middle

[0092] 2 points: the operation was stuck at the start of sliding, and the frictional feeling after sliding was strong

[0093] 3 points: the operation was stuck at the start of sliding, and the frictional feeling after sliding was weak

[0094] 4 points: the operation was slightly stuck at the start of sliding, but no frictional feeling was felt during the operation

[0095] 5 points: no sticking occurred at the start of sliding, and no frictional feeling was felt during the operation.

[0096] Example 1

[0097] An acrylic polymer A having a polymerizable group 216 parts by weight, PMMA Beads A 1 part by weight, a photoinitiator Al part by weight, and a photoinitiator Bl part by weight were dissolved in methyl ethyl ketone 117 parts by weight. After casting this solution onto a PET film using a wire bar #14, the sample was placed in an oven at 100°C for 1 minute to evaporate the solvent, and a low friction layer having a thickness of about 12 μm was formed. Then, the low friction layer was irradiated with ultraviolet rays from a high-pressure mercury lamp (with a cumulative light amount of about 100 mJ / cm 2 UV curing treatment was performed by irradiating the low friction layer with ultraviolet rays from a high-pressure mercury lamp for about 5 seconds, and a low friction film was obtained.

[0098] Example 2

[0099] An acrylic polymer B having a polymerizable group 50 parts by weight, cellulose acetate propionate 4 parts by weight, urethane acrylate 76 parts by weight, silicone acrylate 1 part by weight, photoinitiator Al part by weight, and photoinitiator Bl part by weight were dissolved in a mixed solvent of methyl ethyl ketone 176 parts by weight and 1-butanol 28 parts by weight. After casting this solution onto a PET film using a wire bar #18, the sample was placed in an oven at 80°C for 1 minute to evaporate the solvent, and a low friction layer having a thickness of about 9 μm was formed. Then, the low friction layer was irradiated with ultraviolet rays from a high-pressure mercury lamp (with a cumulative light amount of about 100 mJ / cm 2 UV curing treatment was performed by irradiating the low friction layer with ultraviolet rays from a high-pressure mercury lamp for about 5 seconds, and a low friction film was obtained.

[0100] Comparative Example 1

[0101] Acrylic polymer A having a polymerizable group 216 parts by weight, PMMA Beads B 1 part by weight, photoinitiator Al parts by weight, photoinitiator Bl parts by weight were dissolved in methyl ethyl ketone 117 parts by weight. After casting this solution on a PET film using a wire bar #14, the solution was left in an oven at 100°C for 1 minute to evaporate the solvent, and a low-friction layer having a thickness of about 8 μm was formed. Then, the low-friction layer was irradiated with ultraviolet rays from a high-pressure mercury lamp for about 5 seconds (with a cumulative light amount of about 100 mJ / cm 2 UV curing treatment was performed, and a low-friction film was obtained.

[0102] Comparative Example 2

[0103] Acrylic polymer 34.2 parts by weight, urethane-modified copolymerized polyester resin 20 parts by weight, acrylic UV-curable compound containing nanosilica 166.3 parts by weight, silicone acrylate 0.2 parts by weight, photoinitiator Al parts by weight, photoinitiator Bl parts by weight were dissolved in methyl ethyl ketone 179 parts by weight. After casting this solution on a PET film using a wire bar #16, the solution was left in an oven at 80°C for 1 minute to evaporate the solvent, and a low-friction layer having a thickness of about 5 μm was formed. Then, the low-friction layer was irradiated with ultraviolet rays from a high-pressure mercury lamp for about 5 seconds (with a cumulative light amount of about 100 mJ / cm 2 UV curing treatment was performed, and a low-friction film was obtained.

[0104] Comparative Example 3

[0105] PM-A15FLGM (manufactured by ELECOM) as a commercially available protective sheet for smartphones is praised on the package as "the ultimate finger slide film" and "super smooth film", and therefore, it was used as a comparative example of a film having good finger sliding properties.

[0106] Comparative Example 4

[0107] PM-A15FLST (manufactured by ELECOM) as a commercially available protective sheet for smartphones is also praised on the package as "smooth finger sliding" and "super smooth film", and therefore, it was used as a comparative example of a film having good finger sliding properties.

[0108] The results of evaluating the properties of the low-friction films obtained in the examples and comparative examples are shown in Table 1.

[0109] [Table 1]

[0110]

[0111]

[0112] From the results of Table 1, it is clear that the dynamic friction coefficient and the relative dynamic friction coefficient of the low-friction film of the examples are low, and the finger sliding property is excellent. On the other hand, as in Comparative Examples 1, 3, and 4, only when the sharpness is high, the finger sliding property is not improved. Furthermore, as in Comparative Example 2, only the maximum cross-sectional height is increased, and the finger sliding property is also worse than the examples.

[0113] Industrial applicability

[0114] The low-friction film of the present application can be used as a surface protection or covering film for covering the surface of various shaped bodies such as a touch panel display in a personal computer (tablet PC or the like), a smart phone, a frame of a household appliance, a building material, and the like, and is particularly useful as a film for improving the touch comfort by imparting low friction to a portion that is operated by contact with a hand.

Claims

1. A film comprising a low-friction layer disposed at a surface layer, the low-friction layer being formed from a cured product of a curable composition containing a curable resin and a cellulose ester, and the surface of the low-friction layer having a kurtosis (Rku) of 2 to 100 and a maximum cross-sectional height (Rt) of 1 to 30 μm, wherein the curable resin containing a (meth)acrylic polymer having a polymerizable group, and at least one selected from the group consisting of a urethane (meth)acrylate and a silicone (meth)acrylate, the proportion of the urethane (meth)acrylate being 10 to 300 parts by weight per 100 parts by weight of the (meth)acrylic polymer having a polymerizable group, the proportion of the silicone (meth)acrylate being 0.1 to 10 parts by weight per 100 parts by weight of the (meth)acrylic polymer having a polymerizable group, and the proportion of the cellulose ester being 0.1 to 30 parts by weight per 100 parts by weight of the curable resin.

2. The film according to claim 1, having a dynamic friction coefficient of 0.25 or less at a surface thereof.

3. The film according to claim 1, having a relative dynamic friction coefficient of 0.3 or less at a surface thereof.

4. The film according to any one of claims 1 to 3, wherein, The curable composition does not contain microparticles.

5. The film according to any one of claims 1 to 3, wherein, The low-friction layer is laminated on a substrate layer formed from a transparent resin.

6. The film according to any one of claims 1 to 3, having a silicon atom presence ratio of less than 10% at a surface thereof, and a fluorine atom presence ratio of less than 20% at a surface thereof.

7. A method for producing a film according to any one of claims 1 to 6, the method comprising: a curing step of curing a curable composition containing a curable resin.

8. A shaped body provided with the film according to any one of claims 1 to 6 at a surface thereof.

9. The shaped body according to claim 8, which is a touch panel display.

Images