Release film, method for producing same, and film laminate

Abstract

The purpose of the present invention is to provide a mold release film which exhibits a small release force that can be stably used in a manufacturing process, and which does not cause deformation of a mold release layer. A mold release film having a mold release layer on at least one surface of a base film, in which the mold release film has an elastic modulus (E) of 1.5 MPa or more and less than 5.0 MPa as measured from the surface side of the mold release layer using an atomic force microscope, the thickness of the mold release layer is 0.03 [mu] m or more and less than 0.3 [mu] m, and the deformation of the mold release layer is 0.1 [mu] m or less in height difference.

Description

TECHNICAL FIELD

[0001] The present application relates to a release film and a method for manufacturing the same, and a film laminate. BACKGROUND

[0002] In order to protect the surface of an adhesive sheet that contacts an adherend, a release film provided with a release layer on the surface of a base film is used. Patent Documents 1 to 3 disclose an example of a release film. In the case of the release film disclosed in Patent Document 1, it is disclosed that it is a release film provided with a crosslinked resin layer formed of a crosslinked thermoplastic resin, in which, when the melting point of the aforementioned thermoplastic resin that is not crosslinked is Tm (°C), the proportion of the storage elastic modulus of the release film at Tm + 20 (°C) relative to the storage elastic modulus of the release film at Tm (°C) is 50% or more.

[0003] In addition, Patent Document 2 discloses a release sheet that is a release sheet provided with a base material and a release agent layer provided on at least one surface side of the aforementioned base material, in which the aforementioned base material is composed of a plastic film, the aforementioned release agent layer is formed of a release agent composition containing a polyorganosiloxane having a weight average molecular weight of 5,000 or more and 100,000 or less, the thickness of the aforementioned release agent layer is 0.3 μm or more and 1.0 μm or less, and the elastic modulus of the aforementioned release sheet measured from the surface side opposite to the aforementioned base material in the aforementioned release agent layer using an atomic force microscope is 1.5 MPa or more and 5.0 MPa or less.

[0004] In addition, Patent Document 3 discloses a release film that is a release film provided with a release layer provided on one surface side of a base film, in which the adhesion energy of the aforementioned release layer is 35 mJ / m 2 The above 39 mJ / m 2 Hereinafter, an acrylic adhesive tape is attached to the release layer and cut to a size of 50 mm x 300 mm, and in this state, the 180° peeling strength at a tensile speed of 300 mm / minute after heating and holding at 100°C (set temperature) for 1 hour using a hot air oven and then standing for 1 hour at 23°C, 50% RH is 15 mN / cm or less.

[0005] However, in recent years, thinning of liquid crystal televisions, smartphones, tablet computers, and the like has further progressed, and it is necessary to thin various electronic components that constitute these liquid crystal televisions, smartphones, and tablet computers. Thinning of a polarizing plate, which is one of the above-described electronic components, has also rapidly progressed. In the manufacture of liquid crystal televisions and the like that use a polarizing plate, there is a process of peeling a release layer of a release film from an adhesive surface after the release film is attached to a release surface of a protective film, a polarizing plate, an adhesive, and an adhesive surface. Hitherto, in the case where the polarizing plate is thick, peeling of the adhesive surface from the release layer can be performed well, but if an attempt is made to thin the polarizing plate, the polarizing plate loses stiffness, and thus, when the release film is peeled from the adhesive surface, there is a problem in that the protective film and the polarizing plate are also peeled.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2013-189493

[0009] Patent Document 2: Japanese Patent Application Publication No. 2017-149048

[0010] Patent Document 3: Japanese Patent Application Publication No. 2022-36894 SUMMARY

[0011] PROBLEMS TO BE SOLVED BY THE INVENTION

[0012] For the conventional release film disclosed in Patent Documents 1 to 3, if the elastic modulus is high, it cannot be said that the peeling force is sufficiently small, and if the elastic modulus is low, although the peeling force becomes small, deformation of the release layer occurs due to external pressure, and it is not a release film that can be stably used in the above-described process to cope with the above-described situation.

[0013] To solve the above-described problems, an object of the present application is to provide a release film that exhibits a small peeling force that can be stably used in a manufacturing process, and less deformation of a release layer.

[0014] MEANS FOR SOLVING THE PROBLEMS

[0015] To solve the above-described problems, the present application has the following configuration. That is,

[0016] (1) A release film that has a release layer on at least one surface of a base film, in which an elastic modulus (E) of the release film, measured from the release layer surface side using an atomic force microscope, is 1.5 MPa or greater and less than 5.0 MPa, and a thickness of the release layer is 0.03 μm or greater and less than 0.3 μm, and a maximum height difference of the release layer after pressurization at 10 MPa is 0.1 μm or less.

[0017] (2) The release film according to the above (1), wherein an adhesive tape is attached to the release layer, and after being left to stand for 24 hours at 23°C, the release film is peeled from the adhesive tape at a peeling speed of 300 mm / min and a peeling angle of 180°, and the peeling force is 5 mN / 50 mm or more and 100 mN / 50 mm or less.

[0018] (3) A film laminate comprising an optical member attached to the release film according to the above (1) via an adhesive layer.

[0019] (4) A method for producing a release film having a release layer on at least one surface of a base film, the method comprising a step of applying a release agent to the base film, and a step of curing the applied release agent, at least one of the release agents having at least one absorption selected from the group consisting of vC-H, vSi-H, δSi-CH3, vSi-C, and vSi-O-Si in a spectrum measured by IR measurement, and pyrolysis products of the following formulas (1) to (5) being detected by pyrolysis gas chromatography mass spectrometry, and the molar ratios of the substituents Si-CH3, Si-CH2CH2CH2CH2CH=CH2, and Si-H calculated from 1H NMR spectrum being 90.0 or more and 99.0 or less, 0.3 or more and 3.0 or less, and 0.3 or more and 3.0 or less, respectively.

[0020] [Chemical Formula 1]

[0021]

[0022] (n represents an integer of 1 to 20)

[0023] [Chemical Formula 2]

[0024]

[0025] (n represents an integer of 1 to 20)

[0026] [Chemical Formula 3]

[0027]

[0028] (m represents an integer of 1 to 10)

[0029] [Chemical Formula 4]

[0030]

[0031] [Chemical Formula 5]

[0032] CH2=CHCH2CH2CH=CH2 (5)

[0033] Effects of the Invention

[0034] The release film of the present invention has a small peeling force that enables stable use in a production process, and the release layer has little deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] [ Figure 1 ] is a schematic cross-sectional view of an example of the release film of the present invention.

[0036] [ Figure 2 ] is a diagram showing an example of what should be paid attention to when measuring the height difference of the deformation of the release layer of the release film of the present invention. DETAILED DESCRIPTION

[0037] The present invention provides a release film having a release layer on at least one surface of a base film, wherein the elastic modulus (E) of the release film, as measured from the release layer side using an atomic force microscope, is 1.5 MPa or more and less than 5.0 MPa, the thickness of the release layer is 0.03 μm or more and less than 0.3 μm, and the deformation of the release layer is 0.1 μm or less in terms of height difference.

[0038] The substrate film in the present invention is preferably composed of a plastic film. Examples of such plastic films include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene and polymethylpentene, polycarbonate, and polyvinyl acetate. These plastic films may be single-layer or multilayered, comprising two or more layers of the same or different types. Of these, polyester films are preferred, with polyethylene terephthalate films being particularly preferred. Polyethylene terephthalate films are less likely to generate dust during processing and use, and thus can effectively prevent coating defects caused by dust.

[0039] In addition, according to expectation, the surface treatment or primer treatment based on oxidation method, embossing method etc. can be implemented to one or both sides of the laminated release layer of substrate film.By implementing this treatment, it is easy to improve the adhesion of substrate film and release layer.As the above-mentioned oxidation method, for example, corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet type), flame treatment, hot air treatment, ozone treatment, ultraviolet irradiation treatment etc. can be enumerated.In addition, as embossing method, for example, sandblasting method, spraying treatment method etc. can be enumerated.These surface treatment methods can be appropriately selected according to the type of substrate film.From the aspect of effect and operability, preferably corona discharge treatment method.

[0040] The thickness of the base film is preferably 10 μm or more, more preferably 15 μm or more, and further preferably 20 μm or more. In addition, the thickness is preferably 300 μm or less, more preferably 200 μm or less, and further preferably 125 μm or less. By making the thickness of the base film 10 μm or more, wrinkles are less likely to be introduced when the film is handled or when heat is applied in subsequent processes, and thus the handling properties are easily improved. In addition, by making the thickness of the base film 300 μm or less, the stiffness of the film does not become too strong, and the handling properties are easily improved.

[0041] For the release film of the present application, the elastic modulus (E) of the release film measured from the aforementioned release layer side using an atomic force microscope is 1.5 MPa or more and less than 5.0 MPa. The elastic modulus (E) of the release film is preferably 1.5 MPa or more and 4.2 MPa or less. If the elastic modulus (E) of the release film is less than 1.5 MPa, the release layer deforms due to external pressure, and the deformation is transferred to the adhesive layer, resulting in appearance defects. If it is 5.0 MPa or more, the peeling force becomes heavy, and the handling properties deteriorate. Note that in the present application, the elastic modulus of the release film is measured using the method described later. As a method for making the elastic modulus of the release film fall within the aforementioned range, for example, there are a method for adjusting the crosslinking density of the resin forming the release layer; a method for making the release layer coating solution contain a low-molecular-weight resin; a method for adjusting the thickness of the release layer; and the like.

[0042] The release film of the present application has a release layer on at least one surface of a base film. As a material for forming the release layer, for example, there are alkyd resin-based release agents, polyolefin-based release agents, long-chain alkyl-containing resin-based release agents, fluorine-based release agents, silicone-based release agents, copolymer resin-based release agents containing acrylic-silicone-based graft copolymers, and the like. Among these, from the viewpoint of exhibiting excellent release properties and heat resistance, a silicone-based release agent is preferred. When classified by the reaction mode, silicone-based release agents include heat-curing types such as addition reaction types and condensation reaction types, ultraviolet-curing types, electron beam-curing types, and heat and ultraviolet-curing types, but any silicone-based release agent can be used.

[0043] The release film of the present application can have a primer layer between the release layer and the base film. By selecting the type of the primer layer, it is possible to prevent the release layer from peeling off from the base film, or to improve the adhesion of the release layer to the base film, or to prevent the elution of elution products such as oligomers from the base film to the surface of the release layer.

[0044] As the primer layer, for example, a coating agent using a polyester-based resin, a urethane-based resin, an acrylic-based resin, a resin containing an oxazoline group, a resin containing a carbodiimide group, a resin containing an epoxy group, a resin containing an isocyanate group, and a copolymer thereof, and a coating agent using natural rubber, synthetic rubber as a main component, and the like can be given. These resins can be contained singly or in combination of two or more kinds. In the case where the release layer is formed on the base film, the primer layer can be coated at once or can be coated multiple times.

[0045] In the release film of the present application, the thickness of the release layer is preferably 0.03 μm or more and less than 0.3 μm. The thickness of the release layer is further preferably 0.05 μm or more and 0.2 μm or less. If the thickness of the release layer is 0.03 μm or more, the peeling force easily becomes light, and the handleability is improved, and if it is less than 0.3 μm, the release layer is not easily broken at the time of peeling.

[0046] In the release film of the present application, the height difference of the deformation of the release layer is preferably 0.1 μm or less. The height difference of the deformation of the release layer can be measured by the method described later. The height difference of the deformation of the release layer is further preferably 0.08 μm or less. If the height difference of the deformation of the release layer exceeds 0.1 μm, the deformation of the release layer is transferred to the adhesive, and when the adhesive is attached to the optical member, a defective appearance or the like occurs. As a method of suppressing the deformation of the release layer, for example, a method of adjusting the crosslinking density by adjusting the amount of Si-O-Si, Si-CH2CH2CH2CH2CH=CH2 in the resin forming the release layer, a method of making the release layer coating solution contain a low molecular weight resin, a method of adjusting the thickness of the release layer, and the like can be given.

[0047] In the present application, the peeling force of the release film from the adhesive tape when the tape is peeled at a peeling speed of 300 mm / min and a peeling angle of 180° after the tape is attached to the release layer and left to stand for 24 hours at 23°C is preferably 5 mN / 50 mm or more and 100 mN / 50 mm or less. The peeling force is further preferably 5 mN / 50 mm or more and 60 mN / 50 mm or less. If the peeling force is less than 5 mN / 50 mm, there is a case where the release film is easily peeled at the time of handling. In addition, if the peeling force exceeds 100 mN / 50 mm, the handleability easily becomes poor. Note that in the present application, the peeling force is measured by the method described later.

[0048] The present application is a method for producing a release film having a release layer on at least one side of a base film, which includes a step of applying a release agent to a base film, and a step of curing the applied release agent, at least one of the release agents having at least the absorptions of vC-H, vSi-H, δSi-CH3, vSi-C, and vSi-O-Si in a spectrum measured by IR measurement, detecting the following formula (1) by pyrolysis gas chromatography mass spectrometry, and detecting the following general formula (2), the following general formula (3), the following general formula (4), and the following general formula (5) pyrolysis products, according to 1 The molar ratios of the substituents Si-CH3, Si-CH2CH2CH2CH2CH=CH2, and Si-H calculated from the H NMR spectrum are each 90 or greater but less than 99, 0.3 or greater but less than 3.0, and 0.3 or greater but less than 3.0.

[0049] In the present application, as the method for measuring the IR measurement, the pyrolysis gas chromatography mass spectrometry (hereinafter, sometimes referred to as pyrolysis GC / MS measurement), and the H NMR spectrum, for example, a method of adjusting the main skeleton of the resin forming the release layer, a method of adjusting the content of the low molecular weight resin can be mentioned. 1 The method for measuring the H NMR spectrum to be the above-mentioned result is, for example, a method of adjusting the main skeleton of the resin forming the release layer, a method of adjusting the content of the low molecular weight resin.

[0050] [Chemical Formula 6]

[0051]

[0052] (n represents an integer of 1 to 20)

[0053] [Chemical Formula 7]

[0054]

[0055] (n represents an integer of 1 to 20)

[0056] [Chemical Formula 8]

[0057]

[0058] (m represents an integer of 1 to 10)

[0059] [Chemical Formula 9]

[0060]

[0061] [Chemical Formula 10]

[0062] CH2=CHCH2CH2CH=CH2 (5)

[0063] The method for producing the release film of the present application includes a step of applying a release agent to a base film, and a step of curing the applied release agent.

[0064] In the manufacturing method of the release film of the present application, as the step of applying the release agent on the base film, a general coating method can be used. For example, gravure coating, gravure reverse coating, lip coating, die coating, microgravure coating, Meyer rod coating, multi-stage reverse coating, and the like can be used.

[0065] In the manufacturing method of the release film of the present application, as the step of curing the applied release agent, there is no particular limitation, and heat treatment at 100 to 200°C for 5 to 40 seconds, preferably heat treatment at 120 to 160°C for 8 to 40 seconds, is preferable. When 1 ppm or more of residual solvent remains in the release layer and the release film is not sufficiently cured, there are cases where the release layer is deformed, the peeling force is heavy, and the adhesion to the base material is poor. In addition, as needed, heat treatment and irradiation of active energy rays such as ultraviolet rays can be used in combination.

[0066] As the optical member to be attached to the surface of the adhesive layer of the release film of the present application, a panel constituent member used in the manufacturing process of a polarizing plate, a display panel, and the like used in a liquid crystal television, a smart phone, a tablet, and the like can be given.

[0067] In the present application, the adhesive is not particularly limited, and an acrylic adhesive is preferable. In addition, an ultraviolet-curable adhesive and the like can be given. By irradiating ultraviolet rays to the ultraviolet-curable adhesive, the base polymer is crosslinked by the polymerizable compound, and the storage elastic modulus of the adhesive is increased. The composition of the ultraviolet-curable adhesive is not particularly limited, and generally, a base polymer and a polymerizable compound are contained. The polymerization and curing method by ultraviolet irradiation can be any of a radical type, a cation type, an anion type, and a photo-induced alternating copolymerization type which does not require an initiator can be used. In addition, a mixed type in which these are compounded can also be used. Generally, a radical type or a cation type is often used.

[0068] As the polymerizable compound, various compounds such as a polyester-based, an acrylic-based, a urethane-based, an amide-based, a silicone-based, an epoxy-based, and the like, including a monomer, an oligomer, a prepolymer, and the like of an ultraviolet-curable type can be given. The polymerizable compound preferably has a functional group having ultraviolet polymerizability, and among them, a monomer and an oligomer component of an acrylic-based which contains two or more of the functional groups are preferable. Two or more of the polymerizable functional groups can be the same or different. As the ultraviolet-curable acrylic-based compound, a multifunctional acrylate, an epoxy acrylate, a urethane acrylate, a polyester acrylate, a polyether acrylate, a spiroacetal-based acrylate, and the like can be given. These polymerizable compounds can be present in the adhesive composition, or can be bonded to the functional group such as a hydroxyl group of the base polymer.

[0069] The ultraviolet-curable adhesive preferably contains a photopolymerization initiator. The photopolymerization initiator is a substance that generates radicals, acids, bases, or the like by ultraviolet irradiation, and can be appropriately selected depending on the type of the polymerizable compound. In photoradical polymerization, a photoradical generator is preferably used, in photocationic polymerization, a photoacid generator is preferably used, and in photanionic polymerization, a photobase generator is preferably used. As the photoradical generator, a compound having one or more radical generation points in the molecule can be used, and examples thereof include hydroxy ketones, benzyl dimethyl ketal, amino ketones, acyl phosphine oxide, benzophenone, and trihalomethyl-containing triazine derivatives.

[0070] The base polymer of the ultraviolet-curable adhesive is not particularly limited, and an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyvinyl ether, a vinyl acetate / vinyl chloride copolymer, a modified polyolefin, an epoxy-based polymer, a fluorine-based polymer, a natural rubber, a synthetic rubber, or the like can be appropriately used.

[0071] As the adhesive having excellent optical transparency and adhesiveness, an acrylic adhesive using an acrylic polymer as the base polymer is preferably used. In the case of the acrylic adhesive, the content of the acrylic base polymer with respect to the total amount of the solid components of the adhesive composition is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more.

[0072] As the acrylic polymer, a polymer having a monomer unit of an alkyl (meth)acrylate as the main skeleton can be preferably used. Note that, in the present specification, "(meth)acrylic acid" means acrylic acid and / or methacrylic acid. As the alkyl (meth)acrylate, an alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group can be preferably used. The content of the alkyl (meth)acrylate with respect to the total amount of the monomer components constituting the base polymer is preferably 40% by mass or more, more preferably 50% by mass or more, and further preferably 60% by mass or more. The acrylic base polymer can be a copolymer of a plurality of alkyl (meth)acrylates. The arrangement of the monomer units can be random or block.

[0073] The acrylic base polymer preferably contains an acrylic monomer unit having a crosslinkable functional group as a copolymerization component. In the case where the base polymer has a crosslinkable functional group, curing by ultraviolet irradiation can be easily performed. As the acrylic monomer having a crosslinkable functional group, a hydroxyl group-containing monomer and a carboxyl group-containing monomer can be mentioned. Among them, a hydroxyl group-containing monomer is preferably contained as the copolymerization component of the base polymer. In the case where the base polymer has a hydroxyl group-containing monomer as the monomer unit, the crosslinkability of the base polymer can be improved, and there is a tendency to suppress the whitening of the adhesive in a high-temperature high-humidity environment, and an adhesive having high transparency can be obtained.

[0074] The acrylic base polymer preferably contains a high-polarity monomer unit such as a nitrogen-containing monomer in addition to the above-described alkyl (meth)acrylate and hydroxyl-containing monomer units. By containing a high-polarity monomer unit such as a nitrogen-containing monomer unit in addition to the hydroxyl-containing monomer unit, the adhesive has high adhesion and holding power, and white turbidity under high-temperature high-humidity environments can be suppressed.

[0075] The acrylic polymer that is the base polymer can be obtained by polymerizing the above-described monomer components using various known methods such as solution polymerization, emulsion polymerization, and bulk polymerization. From the viewpoint of the balance of properties such as adhesion, holding power, and cost of the adhesive, the solution polymerization method is suitable.

[0076] A crosslinking structure can be introduced into the base polymer of the ultraviolet-curable adhesive. The formation of the crosslinking structure can be performed, for example, by adding a crosslinking agent after polymerization of the base polymer and heating. As the crosslinking agent, a generally used crosslinking agent such as an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a carbodiimide-based crosslinking agent, and a metal chelate-based crosslinking agent can be used. In addition, by mixing a radical-polymerizable compound having a functional group capable of bonding to a functional group of the base polymer and a radical-polymerizable functional group with the base polymer, a radical-polymerizable functional group can be introduced into the base polymer. As the functional group capable of bonding to the functional group of the base polymer, an isocyanate group is preferred. Since the isocyanate group forms a urethane bond with the hydroxyl group of the base polymer, the introduction of the radical-polymerizable functional group into the base polymer can be easily performed.

[0077] In the adhesive composition, a silane coupling agent, an adhesion promoter can be contained for the purpose of adjusting the adhesion. In addition, a plasticizer, a softening agent, a deterioration-preventing agent, a filler, a coloring agent, an antioxidant, a surfactant, an antistatic agent, and the like can be contained as additives.

[0078] The adhesive can be a single layer, or can be a multilayer configuration in which a plurality of adhesives are stacked. In the case where the adhesive is a multilayer configuration, at least one layer can be an ultraviolet-curable adhesive, or all the layers can be ultraviolet-curable adhesives.

[0079] The thickness of the adhesive is preferably 20 μm or more. If the thickness of the adhesive is 20 μm or more, the front transparent member such as the touch panel, the front transparent plate, and the like can have step difference absorption to the step difference of the printed portion of the front transparent member when bonded. The upper limit of the thickness of the adhesive is not particularly limited, and in view of the light weight and thinness of the image display device, the ease of formation of the adhesive, the workability, and the like, it is preferably 500 μm or less, more preferably 300 μm or less, and further preferably 100 μm or less. In the method for producing the release film of the present application, at least one of the aforementioned release agents has at least the absorptions of vC-H, vSi-H, δSi-CH3, vSi-C, and vSi-O-Si in the spectrum measured by IR measurement. The absorption of vC-H in the spectrum measured by IR measurement means the absorption near 2964 cm -1 , the absorption of vSi-H means the absorption near 2168 cm -1 , the absorption of δSi-CH3 means the absorption near 1412 cm -1 , the absorption of vSi-C means the absorption near 1261 cm -1 and 801 cm -1 , and the absorption of vSi-O-Si means the absorption near 1096 cm -1 and 1022 cm -1 . In the present application, the IR measurement means infrared spectroscopy, and is measured by the method described later.

[0080] In the method for producing the release film of the present application, the pyrolysis GC / MS measurement is measured by the method described later.

[0081] In the method for producing the release film of the present application, the molar ratio of the substituents Si-CH3, Si-CH2CH2CH2CH2CH=CH2, and Si-H calculated from the1H NMR spectrum is each preferably 90 or more and 99 or less, 0.3 or more and 3.0 or less, and 0.3 or more and 3.0 or less. 1 The peak of the substituent Si-CH3 calculated from the1H NMR spectrum means the peak near -0.1 to 0.4 ppm, the peak of Si-CH2CH2CH2CH2CH=CH2 means the peak near 5.8 ppm, and the peak of Si-H means the peak near 4.7 ppm. Note that in the present application, the1H NMR spectrum is measured by the method described later. 1 1

[0082] In the at least one release agent for forming the release layer, the absorption of the spectrum measured by IR measurement, the detected substance in the pyrolysis GC / MS measurement, and the molar ratio of the substituents calculated from the1H NMR spectrum are used. 1 ​​The molar ratio of the substituents calculated from the H NMR spectrum is in the range of the above-mentioned state, and the release film can be produced, which is the object of the present application, by forming a release layer using the release agent in the above-mentioned state, range, and thus the elastic modulus of the aforementioned release film and the deformation of the release layer measured from the aforementioned release layer side using an atomic force microscope are in the range of the object of the present application.

[0083] Examples

[0084] Hereinafter, the present application will be described in more detail using examples, but the present application is not limited to the following examples.

[0085] The measurement method used in the present application is described below.

[0086] [Measurement method]

[0087] (1) Measurement of the elastic modulus (E) of the release film using an atomic force microscope

[0088] The substrate film side of the release film was attached to a sample stage made of stainless steel using a double-sided adhesive tape. Next, the surface of the release layer side of the release film was tapped at 600 nm / s using a probe microscope (manufactured by Shimadzu Corporation, product name "SPM-9700") equipped with a silicone probe (manufactured by Team nanotec, product name "LRCH", radius of curvature: 250 nm, spring constant: 0.2 N / m), and a force curve was obtained. Based on the shape of the obtained force curve, the elastic modulus (E) (MPa) of the release film was calculated using the JKR 2-point method.

[0089] (2) Thickness of the release layer

[0090] After embedding the release film in resin, a small piece for transmission electron microscopy was taken out in the cross-sectional direction using the FIB method, and the total thickness of the release layer of the TEM observation image obtained by observing the cross section of the aforementioned small piece was measured at 3 points using a transmission electron microscope (TEM, manufactured by JEOL Ltd., model name: JEM-F200, acceleration voltage 200 V, magnification 200,000 times), and the average value of the obtained values was used as the thickness.

[0091] (3) Height difference of the deformation of the release layer

[0092] After 10 sheets of the release film were stacked with the base material side in contact with the release layer side, it was cut into 5 cm x 5 cm. Next, under the condition that a pressure of 10 MPa was applied in the stacking direction, it was left to stand for 24 hours at 23°C. Then, using a laser microscope (manufactured by KEYENCE Corporation, model name: Laser Microscope VK-X200), the surface of the release layer of the 5th release film from the top of the stack was observed under the conditions of an objective lens of 150 times, an ocular lens of 20 times (overall magnification of 3000 times). Since particles were added in the base material film for the purpose of preventing blocking, easy sliding, and the like, the horizontal distance of 10 μm was measured for 5 sites where particles of 0.5 μm or more (indicated by reference numeral 4) did not enter, and the maximum difference in level was taken as the difference in level of the deformation of the release layer. Figure 2

[0093] (4) Peeling force of release film and adhesive tape

[0094] On the surface of the release layer side of the release film, a polyester adhesive tape (Nitto Denko Corporation No. 31B tape, 50 mm width) was attached while being pressure-bonded using a 5 kg roller, and after it was left to stand for 24 hours at 23°C, the tape was peeled off using a tensile testing machine at a peeling speed of 300 mm / minute and a peeling angle of 180°, and the peeling strength at that time was measured.

[0095] (5) Absorption of spectrum measured by IR measurement

[0096] The release agent was measured using an IR measurement device (iS5 manufactured by Thermo Fisher SCIENTIFIC, sample scanning number: 64 times, background scanning number: 64 times, resolution: 8.0), and the absorption of the obtained spectrum was as follows. The case where all of the following absorptions were confirmed was taken as O, and the case where one or more of them was not confirmed was taken as X.

[0097] Absorption of vC-H: 2964 cm -1 Absorption near

[0098] Absorption of vSi-H: 2168 cm -1 Absorption near

[0099] Absorption of δSi-CH3: 1412 cm -1 Absorption near

[0100] Absorption of vSi-C: 1261 cm -1 Absorption near and 801 cm -1 Absorption near

[0101] Absorption of vSi-O-Si: 1096 cm -1 Absorption near and 1022 cm -1 Absorption near​

[0102] (6) Detectable substances in pyrolysis GC / MS measurement of release agents

[0103] The release agent was measured and analyzed using a gas chromatograph 7890A manufactured by Agliment Technologies (conditional column: "Ultra Alloy (registered trademark)"-5 (MS / HT), column temperature: 40°C (3 minutes) - 320°C (18 minutes) (rate: 20°C / min), injection temperature: 300°C), a mass spectrometer JMS-Q1050GC manufactured by JEOL Ltd. (conditional ionization mode: EI+, scan range: m / z 10.0-800.0, scan rate: 0.5 sec / scan), and a comprehensive pyrolysis analysis system (Pyrolyzer PY-2020iD manufactured by Frontier Labs, Inc., temperature: 600°C). If all of the following formula (1), general formula (2), general formula (3), general formula (4), and general formula (5) were detected, it was marked as 0, and if none of them were detected, it was marked as ×.

[0104] [Chemical Formula 11]

[0105]

[0106] (n represents an integer from 1 to 20)

[0107] [Chemical Formula 12]

[0108]

[0109] (n represents an integer from 1 to 20)

[0110] [Chemical Formula 13]

[0111]

[0112] (m represents an integer from 1 to 10)

[0113] [Chemical Formula 14]

[0114]

[0115] [Chemical Formula 15]

[0116] CH2=CHCH2CH2CH=CH2 (5)

[0117] (7) According to 1 Substituents calculated from H NMR spectrum

[0118] The release agent was measured using an NMR measuring device (ECA-400 manufactured by Jeol Resonance Co., Ltd.).1 HNMR spectrum, molar ratio of substituent groups Si-CH3, Si-CH2CH2CH2CH2CH=CH2, Si-H was calculated.

[0119] [Example 1]

[0120] A primer coating solution was prepared by mixing 3 parts by weight of BY24-846B (Toray Dow Corning Co., Ltd., content 98% by weight) as 3-glycidoxypropyltrimethoxysilane, 1 part by weight of BY24-846C (Toray Dow Corning Co., Ltd., content 99% by weight) as 3-methacryloxypropyltrimethoxysilane, 2 parts by weight of BY24-846E (Toray Dow Corning Co., Ltd., content 38% by weight) as bis(ethylacetoacetate)(2,4-pentanedionato)aluminum, 50 parts by weight of toluene, and 50 parts by weight of isopropyl alcohol (IPA).

[0121] A release layer coating solution 1 was prepared by mixing 4 parts by weight of the obtained silicone composition for release property cured film formation, 0.08 parts by weight of platinum-based catalyst SRX212 (Dow Toray Co., Ltd.) as a curing agent, 50 parts by weight of toluene, and 46 parts by weight of n-heptane.

[0122] On a polyethylene terephthalate film (Toray Industries, Inc. "Lumirror (registered trademark) " XF60R) having a thickness of 38 μm, a primer coating solution was applied with a No. 3 Meyer bar so that the dry coating thickness would be 0.05 μm, and after drying and curing at 100°C for 5 seconds, a release layer coating solution 1 was continuously applied with a No. 5 Meyer bar so that the release layer thickness would be 0.15 μm, and after drying and curing at 160°C for 20 seconds, a release film was obtained. The elastic modulus, release layer thickness, peeling force, and unevenness of the release layer were measured, and the results are shown in Table 1. A release film having a small peeling force and no unevenness of the release layer was obtained.

[0123] [Example 2]

[0124] In Example 1, instead of the release layer coating solution 1, 100 parts by weight of a dimethylsiloxane-methylhexenylsiloxane copolymer in which both ends of the molecular chain were capped with dimethylhexenylsiloxy groups (viscosity 200 mPa-s), 13.8 parts of a dimethylpolysiloxane in which both ends were capped with dimethylhydrogensiloxy groups (hydrogen atom content bonded to silicon atoms 0.12% by weight, viscosity 15 mPa-s), 1.5 parts of a methylhydrogenpolysiloxane in which both ends were capped with trimethylsiloxy groups (hydrogen atom content bonded to silicon atoms 1.6% by weight, viscosity 20 mPa-s), 0.3 parts of 1-ethynyl-1-cyclohexanol, and 10 parts of a dimethylpolysiloxane in which both ends were capped with trimethylsiloxy groups (viscosity 300,000 mPa-s) were uniformly mixed. Next, a complex salt of chloroplatinic acid and 1,3-divinyltetramethyldisiloxane was added to the mixture in an amount such that the platinum metal content would be 200 ppm by weight, and an organosilicon composition for release cured film formation having a viscosity of about 400 mPa-s was prepared. To 3 parts by weight of the obtained organosilicon composition for release cured film formation and 59.2 g of a cyclic tetrasiloxane containing hydrogen atoms bonded to silicon atoms, 0.7 g of platinum-supported carbon powder (platinum content 0.5% by weight) was added, and heated to 150°C while stirring. Then, 50 g of α-methylstyrene was added dropwise, and further heating and stirring was continued at 150°C for 3 hours. After cooling, filtration was performed, and volatiles were removed by heating to 150°C under reduced pressure. A release layer coating solution 2 was prepared by mixing 1 part by weight of the thus obtained reaction product, 0.08 parts by weight of platinum-based catalyst SRX212 (Dow Toray Co., Ltd.) as a curing agent, 50 parts by weight of toluene, and 46 parts by weight of n-heptane, and a release film was obtained by the same procedure as in Example 1, except for the use of the release layer coating solution 2. The elastic modulus, release layer thickness, peeling force, and unevenness of the release layer were measured, and the results are shown in Table 1. A release film having a small peeling force and no unevenness of the release layer was obtained.

[0125] [Examples 3 and 4]

[0126] The same operation as in Example 1 was performed except that the total thickness of the release layer was changed, to obtain a release film. The elastic modulus, the thickness of the release layer, the peeling force, and the unevenness of the deformation of the release layer were measured, and the results are shown in Table 1. A release film having a small peeling force and no deformation of the release layer was obtained.

[0127] [Comparative Example 1]

[0128] In Example 1, 20 parts by weight of dimethylpolysiloxane in which both terminals of the molecular chain were capped with dimethylvinylsiloxy group (viscosity 2000 mPa-s, vinyl content 0.2% by weight), 80 parts by weight of dimethylpolysiloxane in which both terminals of the molecular chain were capped with dimethylvinylsiloxy group (viscosity 370 mPa-s, vinyl content 0.47% by weight), 14.5 parts by weight of dimethylpolysiloxane capped with dimethylhydrosiloxy group (hydrogen atom content bonded to silicon atom 0.12% by weight, viscosity 15 mPa-s), 1.5 parts by weight of dimethylsiloxane-methylhydrosiloxane copolymer in which both terminals of the molecular chain were capped with trimethylsiloxy group (hydrogen atom content bonded to silicon atom 1.0% by weight, viscosity 70 mPa-s) containing 30 mole% of dimethylsiloxane unit and 70 mole% of methylhydrosiloxane unit, and 0.1 part by weight of 3-methyl-l-butyn-3-ol were uniformly mixed. Then, to the mixture, a complex salt of chloroplatinic acid and 1,3-divinyltetramethyldisiloxane was added in an amount such that the platinum metal amount became 200 ppm, to prepare a release property curing film forming silicone composition having a viscosity of about 300 mPa-s. Using release layer coating liquid 3 in which 8 parts by weight of the obtained release property curing film forming silicone composition, 0.08 parts by weight of platinum-based catalyst PL-50T (manufactured by Shin-Etsu Chemical Co., Ltd.) as a curing agent, and 28 parts by weight of toluene and 64 parts by weight of n-heptane were mixed, the same operation as in Example 1 was performed except for this, to obtain a release film. The elastic modulus, the thickness of the release layer, the peeling force, and the unevenness of the deformation of the release layer were measured, and the results are shown in Table 1. The elastic modulus was low, the peeling force was light, but the release layer was deformed, and the results were poor.

[0129] [Comparative Example 2]

[0130] In Example 1, instead of the release layer coating liquid 1, a release layer coating liquid 3 prepared by mixing 0.1 parts by mass of DEP Clear (Wako Chemical) as a curing agent in a solution of 9 parts by mass of a mixed liquid of toluene, cyclohexanone, and methanol (4.5 / 3.6 / 0.9) mixed with 1 part by mass of a melamine compound (RP-50 manufactured by Sankei Research Institute, Inc., solid content: 50% by mass) as a thermosetting resin, was used, and otherwise, the same operation as in Example 1 was performed to obtain a release film. The elastic modulus, release layer thickness, peeling force, and unevenness of the deformation of the release layer were measured, and the results are shown in Table 1. The result was that the peeling force was severely poor when the elastic modulus was high.

[0131] [Comparative Example 3]

[0132] In Example 1, instead of the release layer coating liquid 1, a release layer coating liquid 3 prepared by mixing 0.1 parts by mass of DEP Clear (Wako Chemical) as a curing agent in a solution of 9 parts by mass of a mixed liquid of toluene, cyclohexanone, and methanol (4.5 / 3.6 / 0.9) mixed with 1 part by mass of a melamine compound (RP-50 manufactured by Sankei Research Institute, Inc., solid content: 50% by mass) as a thermosetting resin, was used, and otherwise, the same operation as in Example 1 was performed to obtain a release film. The elastic modulus, release layer thickness, peeling force, and unevenness of the deformation of the release layer were measured, and the results are shown in Table 1. The result was that the peeling force was severely poor when the elastic modulus was high.

[0133] [Table 1]

[0134]

[0135] As shown in Table 1, the peeling force of the release film according to the embodiments is very small compared to the release film according to the comparative example. In addition, regarding the release film according to the embodiments, the difference in the height of the deformation of the release layer is small.

[0136] Industrial applicability

[0137] The release film according to the present application has a small peeling force that can be stably used in the process, and the difference in the height of the deformation of the release layer is small, and thus can be appropriately used in the manufacture of various electronic components that are thinned (constituting liquid crystal televisions, smartphones, tablet computers that are increasingly thinned).

[0138] Explanation of reference numerals

[0139] 1 base film

[0140] 2 release layer

[0141] 3 release film

[0142] 4 foreign matter

Claims

1. A release film which is a release film having a release layer on at least one side of a base film, wherein, The elastic modulus (E) of the release film measured from the side of the release layer using an atomic force microscope is 1.5 MPa or greater but less than 5.0 MPa, the thickness of the release layer is 0.03 μm or greater but less than 0.3 μm, and the maximum unevenness of the release layer after pressurization at 10 MPa is 0.1 μm or less.

2. The release film of claim 1, wherein, The release film has a release force of 5 mN / 50 mm or greater but 100 mN / 50 mm or less from the adhesive tape when the adhesive tape is peeled off under conditions of a peeling speed of 300 mm / minute and a peeling angle of 180° after the adhesive tape is attached to the release layer and left to stand for 24 hours at 23°C.

3. A film laminate comprising an optical member attached to the release film according to claim 1 via an adhesive layer.

4. A method for producing a release film having a release layer on at least one surface of a base film, the method comprising a step of applying a release agent to the base film and a step of curing the applied release agent, at least one of the release agents has at least one absorption selected from the group consisting of νC-H, νSi-H, δSi-CH3, νSi-C and νSi-O-Si in an IR measurement spectrum, pyrolysis products of the following formulas (1) to (5) are detected by pyrolysis gas chromatography mass spectrometry analysis, the molar ratios of the substituents Si-CH3, Si-CH2CH2CH2CH2CH=CH2 and Si-H calculated from 1H NMR spectra are 90.0 or greater but 99.0 or less, 0.3 or greater but 3.0 or less, and 0.3 or greater but 3.0 or less, respectively, [Chemical Formula 1] n represents an integer of 1 to 20, [Chemical Formula 2] n represents an integer of 1 to 20, [Chemical Formula 3] m represents an integer of 1 to 10, [Chemical Formula 4] [Chemical Formula 5] CH2=CHCH2CH2CH=CH2 (5).

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