JP7699019B2 - Release film and method for producing same - Google Patents

Description

The present invention relates to a release film and a method for producing the same.

To protect the surface of the adhesive sheet that comes into contact with the adherend, a release film with a release layer on the surface of the base film is used.

Patent documents 1 to 3 disclose examples of release films.

The release film disclosed in Patent Document 1 is a release film that includes an antistatic layer that contains a binder and an antistatic agent, and it is disclosed that the release layer is a silicone release layer.

The release film disclosed in Patent Document 2 is a release film having a crosslinked resin layer formed from a crosslinked thermoplastic resin, and when the melting point of the uncrosslinked thermoplastic resin is Tm (°C), the ratio of the storage modulus of the release film at Tm+20 (°C) to the storage modulus of the release film at Tm (°C) is 50% or more.

Patent Document 3 also discloses a release sheet comprising a substrate and a release agent layer provided on at least one side of the substrate, the substrate being made of a plastic film, the release agent layer being formed from 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 release agent layer being 0.3 μm or more and 1.0 μm or less, and the modulus of elasticity of the release sheet measured from the side of the release agent layer opposite the substrate using an atomic force microscope being 1.5 MPa or more and 5.0 MPa or less.

JP 2012-140008 A JP 2013-189493 A JP 2017-149048 A

However, in recent years, LCD TVs, smartphones, tablets, and the like have become thinner, and it has become necessary to make the various electronic components that make up these LCD TVs, smartphones, and tablets thinner. Polarizing plates, one of the electronic components mentioned above, are also rapidly becoming thinner. In the manufacture of LCD TVs and the like that use polarizing plates, there is a process in which the release surface of a release film is laminated onto the adhesive surface of a protective film, a polarizing plate, an adhesive, and the adhesive, and then the release layer of the release film is peeled off from the adhesive surface. Until now, when the polarizing plate was thick, the adhesive surface and the release layer were peeled off well, but when trying to make the polarizing plate thinner, the polarizing plate loses its stiffness, and a problem occurs in that the protective film and polarizing plate are also peeled off when the release film is peeled off from the adhesive surface.

Conventional release films such as those disclosed in Patent Documents 1 to 3 do not exhibit a peeling force small enough to cope with the above-mentioned conditions, and are not release films that can be stably used in the above-mentioned process.

In order to solve the above problems, the present invention aims to provide a release film that exhibits a small peeling force and can be used stably in the manufacturing process.

In order to solve the above problems, the present invention has the following configuration.
(1) 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 measured from the release layer surface side using an atomic force microscope is 0.1 MPa or more and less than 1.5 MPa.
(2) The release film according to (1) above, wherein the release layer is composed of a plurality of layers and the total thickness (A) of the release layer is 0.05 μm or more and 2.0 μm or less.
(3) The release film according to the above (2), wherein the ratio (B/A) of the thickness (B) of the surface layer of the plurality of layers opposite the substrate to the total thickness (A) of the release layer is 0.01 or more and 0.9 or less.
(4) The release film according to (2) or (3) above, wherein the carbon atom concentration of the surface layer of the plurality of layers opposite the substrate is higher than the carbon atom concentration of the layer of the plurality of layers on the substrate side, the oxygen atom concentration of the surface layer opposite the substrate is lower than the oxygen atom concentration of the layer on the substrate side, and the silicon atom concentration of the surface layer opposite the substrate is higher than the silicon atom carbon concentration of the layer on the substrate side.
(5) The release film according to any one of (2) to (4), wherein the surface layer of the plurality of layers opposite the substrate has a carbon atom concentration of 40 atomic % or more and 60 atomic % or less, an oxygen atom concentration of 15 atomic % or more and 30 atomic % or less, and a silicon atom concentration of 20 atomic % or more and 40 atomic % or less.
(6) The release film according to any one of (2) to (5), wherein the layer of the plurality of layers on the substrate side has a carbon atom concentration of 30 atomic % or more and 60 atomic % or less, an oxygen atom concentration of 25 atomic % or more and 40 atomic % or less, and a silicon atom concentration of 15 atomic % or more and 35 atomic % or less.
(7) The release film according to any one of (1) to (6) above, wherein when an adhesive tape is applied to the release layer and allowed to stand at 23° C. for 24 hours, and then the tape is peeled off at a peel speed of 300 mm/min and a peel angle of 180°, the peel strength between the release film and the adhesive tape is 5 mN/50 mm or more and 80 mN/50 mm or less.
(8) The release film according to any one of (1) to (7) above, wherein the surface roughness (Sa) of the release layer is 5 nm or more and 50 nm or less.
(9) The release film according to any one of (1) to (8), wherein the ratio (E/Sa) of the elastic modulus (E) to the surface roughness (Sa) of the release layer is 0.002 MPa/nm or more and less than 0.3 MPa/nm.
(10) A method for producing a release film having a release layer on at least one surface of a base film, the method comprising the steps of applying a release agent to the base film and curing the applied release agent, wherein at least one of the release agents exhibits absorptions of at least νC-H, νSi-H, δSi- _CH3 and νSi-O-Si in a spectrum measured by IR measurement, and the following formula (1) is detected by pyrolysis gas chromatography mass spectrometry, and pyrolysates of the following general formulas (2) and (3) are detected, and the molar ratios of the substituents Si-CH3, Si-H, Si- _CH═CH2 , Si-Ph and Si-OCH3 calculated from the ^1H NMR spectrum are 93.0 or more and 99.0 or less, _0.3 or _more and 3.0 or less, 0.1 or more and 2.0 or less, 0.1 or more and 1.5 or less, and 0.05 or more and 1.0 or less, respectively.

(n is an integer between 1 and 20)

(m is an integer between 1 and 10)

The release film of the present invention exhibits a small peel force that allows stable use in the manufacturing process.

FIG. 1 is a schematic cross-sectional view of an example of the release film of the present invention.

The release film of the present invention is a release film having a release layer on at least one surface of a base film, and the elastic modulus (E) of the release film measured from the release layer surface side using an atomic force microscope is 0.1 MPa or more and less than 1.5 MPa.

The substrate film in the present invention is 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-layered or multi-layered, consisting of two or more layers of the same or different types. Among these, polyester films are preferred, and polyethylene terephthalate films are particularly preferred. Polyethylene terephthalate films are less likely to generate dust during processing and use, and therefore can effectively prevent coating defects due to dust, for example.

If desired, the surface or both surfaces of the base film on which the release layer is to be laminated can be subjected to a surface treatment such as an oxidation method or a roughening method, or a primer treatment. By carrying out such treatment, the adhesion between the base film and the release layer is likely to be improved. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone treatment, and ultraviolet irradiation treatment. Examples of the roughening method include sandblasting and thermal spraying. These surface treatment methods are appropriately selected depending on the type of base film. In terms of effect and operability, corona discharge treatment is preferred.

The thickness of the base film is preferably 10 μm or more, particularly preferably 15 μm or more, and more preferably 20 μm or more. The thickness is also preferably 300 μm or less, particularly preferably 200 μm or less, and more preferably 125 μm or less. By making the thickness of the base film 10 μm or more, the film is less likely to wrinkle when heated during transportation or in a later process, which tends to improve workability. By making the thickness of the base film 300 μm or less, the film does not become too stiff, which tends to improve workability.

The release film of the present invention has an elastic modulus (E) of 0.1 MPa or more and less than 1.5 MPa, measured from the release layer side using an atomic force microscope. The elastic modulus (E) of the release film is preferably 1.0 MPa or more and 1.4 MPa or less. If the elastic modulus (E) of the release film is less than 0.1 MPa, blocking occurs and workability is deteriorated, and if it is 1.5 MPa or more, the peeling force becomes heavy and workability is deteriorated. In the present invention, the elastic modulus (E) of the release film is measured by the method described later. In the present invention, examples of methods for setting the elastic modulus (E) of the release film in the above-mentioned range include a method of adjusting the crosslink density of the resin forming the release layer, a method of adding a low molecular weight resin to the release layer coating liquid, and a method of adjusting the total thickness (A) of the release layer.

The release film of the present invention has a release layer on at least one surface of the base film. Examples of materials for forming the release layer include alkyd resin-based release agents, polyolefin-based release agents, long-chain alkyl group-containing resin-based release agents, fluorine-based release agents, silicone-based release agents, copolymer resin-based release agents including acrylic-silicone graft copolymers, etc. Among these, silicone-based release agents are preferred because they exhibit excellent release properties and heat resistance. Silicone-based release agents can be classified by reaction type into heat-curing types such as addition reaction types and condensation reaction types, ultraviolet curing types, electron beam curing types, and combined heat and ultraviolet curing types, and any of these silicone-based release agents can be used.

The acrylic-silicone graft copolymer used in the present invention is a copolymer of an organopolysiloxane compound having an acrylic group and/or a methacrylic group (hereinafter also referred to as a (meth)acrylic group) and a radically polymerizable monomer having one radically polymerizable group per molecule.

The weight average molecular weight of the acrylic-silicone graft copolymer is not particularly limited, but is 100 to 100,000, preferably 1,000 to 50,000, and more preferably 2,000 to 30,000, in terms of polystyrene, as measured by gel permeation chromatography (hereinafter abbreviated as "GPC") using toluene as the developing solvent. If the weight average molecular weight is less than 100, the residual adhesion rate decreases, and if it exceeds 100,000, dispersibility in the organopolysiloxane composition decreases.

In the present invention, the release layer preferably consists of multiple layers. A release layer consisting of multiple layers may be a release layer formed by applying different types of release agents two or more times, or may be a release layer formed by applying one type of release agent once and then separating it into multiple layers.

The release film of the present invention may have a primer layer between the release layer and the base film. By selecting the type of primer layer, it is possible to prevent the release layer from falling off the base film, to improve the adhesion between the release layer and the base film, and to prevent deposits such as oligomers from the base film from precipitating on the surface of the release layer.

Examples of the primer layer include polyester resins, urethane resins, acrylic resins, oxazoline group-containing resins, carbodiimide group-containing resins, epoxy group-containing resins, isocyanate-containing resins, and copolymers thereof, as well as coating agents mainly composed of natural rubber or synthetic rubber. These resins may be contained alone or in combination of two different types. When a release layer is formed on the base film, the primer layer may be applied in one coat or multiple coats.

Figure 1 shows a schematic cross-sectional view of an example of the release film of the present invention in which the release layer is made up of multiple layers. In the release film 5 of Figure 1, one side of the base film 3 has a release layer 4, and the release layer 4 includes a layer 2 on the base side and a surface layer 1 on the side opposite the base.

In the release film of the present invention, the total thickness (A) of the release layer is preferably 0.05 μm or more and 2.0 μm or less. In the present invention, the total thickness (A) of the release layer refers to the thickness of one release layer when the release layer consists of only one layer. Also, when the release layer consists of multiple layers, it refers to the total thickness of all layers contained in the release layer. The total thickness (A) of the release layer is more preferably 0.1 μm or more and 1.0 μm or less. When the total thickness (A) of the release layer is 0.05 μm or more, the peeling force tends to be lighter and the workability is improved, and when it is 2.0 μm or less, the release layer is less likely to crack during peeling.

When the release layer of the release film of the present invention is composed of multiple layers, the ratio (B/A) of the thickness (B) of the surface layer on the opposite side to the substrate among the multiple layers to the total thickness (A) of the release layer is preferably 0.01 or more and 0.9 or less, more preferably 0.02 or more and 0.8 or less. When the B/A is 0.01 or more or 0.9 or less, the elastic modulus (E) of the release film is likely to be within the above-mentioned range. In the present invention, the surface layer on the opposite side to the substrate refers to the layer that is the furthest from the substrate film among the layers in the release layer when the release layer is composed of multiple layers. In the present invention, an example of a method for adjusting the B/A to the above-mentioned range is to adjust the content of low molecular weight components in the release layer coating liquid.

In the release film of the present invention, it is preferable that the carbon atom concentration of the surface layer opposite the substrate among the multiple layers is higher than the carbon atom concentration of the layer on the substrate side among the multiple layers, the oxygen atom concentration of the surface layer opposite the substrate is lower than the oxygen atom concentration of the layer on the substrate side, and the silicon atom concentration of the surface layer opposite the substrate is higher than the silicon atom carbon concentration of the layer on the substrate side. By making the carbon atom concentration, oxygen atom concentration, and silicon atom concentration of the surface layer opposite the substrate and the layer on the substrate side have the above-mentioned relationship, it becomes easier to adjust the elastic modulus (E) of the release film to the above-mentioned range, and as a result, it is easier to make the peeling force of the release film and the adhesive tape described later to be in the desired range. In addition, in the present invention, the layer on the substrate side refers to a layer other than the layer farthest from the substrate film among the multiple layers when the release layer is composed of multiple layers. In other words, the layer on the substrate side refers to a layer other than the surface layer on the opposite side to the substrate among the multiple layers when the release layer is composed of multiple layers. In the present invention, one method for making the atomic concentrations satisfy the above-mentioned relationship is, for example, to adjust the content ratio of low molecular weight components and high molecular weight components in the release layer coating liquid.

In the release film of the present invention, it is preferable that the carbon atom concentration of the surface layer opposite the substrate among the multiple layers is 40 atm% or more and 60 atm% or less, the oxygen atom concentration is 15 atm% or more and 30 atm% or less, and the silicon atom concentration is 20 atm% or more and 40 atm% or less. By setting the carbon atom concentration, oxygen atom concentration, and silicon atom concentration of the surface layer opposite the substrate to the above ranges, it becomes easier to adjust the elastic modulus (E) of the release film to the above range, and as a result, it becomes easier to set the peeling force between the release film and the adhesive tape described later to the desired range. In the present invention, for example, an example of a method for setting each atomic concentration to the above range is to adjust the content ratio of low molecular weight components and high molecular weight components in the release layer coating liquid.

In the release film of the present invention, it is preferable that the carbon atom concentration of the layer on the substrate side among the multiple layers is 30 atm% or more and 60 atm% or less, the oxygen atom concentration is 25 atm% or more and 40 atm% or less, and the silicon atom concentration is 15 atm% or more and 35 atm% or less. By setting the carbon atom concentration, oxygen atom concentration, and silicon atom concentration of the layer on the substrate side to the above ranges, it becomes easier to adjust the elastic modulus (E) of the release film to the above range, and as a result, it becomes easier to set the peeling force between the release film and the adhesive tape described later to the target range. In the present invention, the carbon atom concentration, oxygen atom concentration, and silicon atom concentration are measured by the method described later. In the present invention, an example of a method for setting each atomic concentration to the above range is to adjust the content ratio of low molecular weight components and high molecular weight components in the release layer coating liquid.

In the present invention, when an adhesive tape is applied to the release layer and left at 23°C for 24 hours, and then the tape is peeled off at a peeling speed of 300 mm/min and a peeling angle of 180°, the peeling force between the release film and the adhesive tape is preferably 5 mN/50 mm or more and 80 mN/50 mm or less. The peeling force is more 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, the release film is easily peeled off during transportation. If the peeling force exceeds 80 mN/50 mm, workability is likely to deteriorate. In the present invention, the peeling force is measured by the method described below.

In the present invention, the surface roughness (Sa) of the release layer is preferably 5 nm or more and 50 nm or less. More preferably, it is 10 nm or more and 40 nm or less. By making it 5 nm or more, charging is less likely to occur during transportation and when the product is rolled up, so that workability is easily improved. In addition, by making it 50 nm or less, the adhesive is less likely to be dented, so that appearance defects are less likely to occur. In the present invention, the surface roughness of the release layer is measured by the method described below. In the present invention, examples of methods for making the surface roughness (Sa) of the release layer within the above range include adjusting the particle size and amount added to improve the slipperiness of the base film and to prevent blocking.

In the present invention, the ratio (E/Sa) of the elastic modulus (E) to the surface roughness (Sa) of the release layer is preferably 0.002 MPa/nm or more and less than 0.3 MPa/nm. The E/Sa is more preferably 0.005 MPa/nm or more and 0.2 MPa/nm or less. If the E/Sa is 0.002 MPa/nm or more, the occurrence of blocking is easily suppressed, and if it is less than 0.3 MPa/nm, the occurrence of dents in the rolled state is easily suppressed. In the present invention, examples of methods for setting E/Sa within the above range include adjusting the crosslink density of the resin forming the release layer, adjusting the content of the low molecular weight resin, and adjusting the particle size and amount added to improve the slipperiness of the base film and prevent blocking.

The method for producing a release film of the present invention is a method for producing a release film having a release layer on at least one surface of a base film, and includes a step of applying a release agent to the base film and a step of curing the applied release agent, wherein at least one of the release agents has absorptions of at least νC-H, νSi-H, δSi-CH ₃ and νSi-O-Si in a spectrum measured by IR measurement, and the following formula (1) is detected by pyrolysis gas chromatography mass spectrometry, and pyrolysates of the following general formulas (2) and (3) are detected, and the molar ratios of the substituents Si-CH ₃ , Si-H, Si-CH═CH ₂ , Si-Ph and Si-OCH ₃ calculated from the ¹ H NMR spectrum are 93.0 or more and 99.0 or less, 0.3 or more and 3.0 or less, 0.1 or more and 2.0 or less, 0.1 or more and 1.5 or less, and 0.05 or more and 1.0 or less, respectively. In the present invention, methods for making the measurement results of IR measurement, pyrolysis gas chromatography mass spectrometry (hereinafter sometimes referred to as pyrolysis GC/MS measurement), and ^1H NMR spectrum as described above include, for example, adjusting the main skeleton of the resin forming the release layer or adjusting the content of low molecular weight resin.

(n is an integer between 1 and 20)

(m represents an integer of 1 to 10)
The method for producing a release film of the present invention includes a step of applying a release agent to a base film, and a step of curing the applied release agent.

In the method for producing a release film of the present invention, a general coating method can be used for the step of applying a release agent to a base film. For example, coating methods such as gravure coating, gravure reverse coating, lip coating, die coating, microgravure coating, Mayer bar coating, and multi-stage reverse coating can be used.

In the method for producing a release film of the present invention, the step of curing the applied release agent is not particularly limited, but it is preferable to perform a heat treatment at 60 to 200°C for 3 to 40 seconds, preferably at 80 to 180°C for 3 to 40 seconds. In addition, if necessary, the heat treatment may be combined with irradiation with active energy rays such as ultraviolet rays.

In the method for producing a release film of the present invention, at least one of the release agents has at least the absorptions of vC-H, vSi-H, δSi-CH ₃ and vSi-O-Si in the spectrum measured by IR measurement. In the spectrum measured by IR measurement, the absorption of vC-H refers to the absorption around 2963 cm ^-1 , the absorption of vSi-H refers to the absorption around 2168 cm ^-1 , the absorption of δSi-CH ₃ refers to the absorption around 1411 cm ^-1 , and the absorption of vSi-O-Si refers to the absorption around 1096 cm ^-1 . In the present invention, IR measurement refers to infrared spectroscopy, and is measured by the method described below.

In the method for producing the release film of the present invention, pyrolysis GC/MS measurement is performed by the method described below.

In the method for producing a release film of the present invention, the molar ratios of the substituents Si- _CH3 , Si-H, Si-CH= _CH2 , Si-Ph, and Si- _OCH3 calculated from a ^1H NMR spectrum are preferably 93.0 or more and 99.0 or less, 0.3 or more and 3.0 or less, 0.1 or more and 2.0 or less, 0.1 or more and 1.5 or less, and 0.05 or more and 1.0 or less, respectively. The peak of the substituent Si- _CH3 calculated from a ^1H NMR spectrum refers to the vicinity of -0.2 to 0.4 ppm, the peak of Si-H refers to the vicinity of 4.6 to 4.9 ppm, the peak of Si-CH= _CH2 refers to the vicinity of 5.6 to 6.2 ppm, the peak of Si-Ph refers to the vicinity of 7.2 to 7.7 ppm, and the peak of Si- _OCH3 refers to the vicinity of 3.4 to 3.5 ppm. In the present invention, ^{the 1} H NMR spectrum is measured by the method described below.

By forming a release layer using at least one release agent whose spectral absorption measured by IR measurement, whose detection material by pyrolysis GC/MS measurement, and whose molar ratio of substituents calculated from ^1H NMR spectrum are in the above-mentioned state and range, it is possible to produce a release film whose elastic modulus (E) of the release film measured from the release layer surface side using an atomic force microscope falls within the range desired by the present invention.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

The measurement method used in the present invention is as follows.
[Measurement method]
(1) Measurement of the elastic modulus (E) of the release film by atomic force microscope The surface of the base film side of the release film prepared in the examples and comparative examples was attached to a stainless steel sample stage using double-sided adhesive tape. Then, 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), tapping was performed on the release layer side surface of the release film at 600 nm/s to obtain a force curve. From the shape of the obtained force curve, the elastic modulus (E) (MPa) of the release film was calculated by the JKR two-point method.

(2) Total thickness of the release layer (A) and the thickness of the surface layer opposite the substrate (B)
After embedding the release film in resin, a small piece for a transmission electron microscope was taken out in the cross-sectional direction by the FIB method, and the cross-section of the small piece was observed using a transmission electron microscope (TEM, manufacturer: JEOL Ltd., type name: JEM-F200, acceleration voltage 200 V, magnification 200,000 times). The total thickness of the release layer and the thickness of the surface layer on the opposite side to the substrate were measured at three points in the TEM observation image obtained by observing the cross-section of the small piece using the transmission electron microscope (TEM, manufacturer: JEOL Ltd., type name: JEM-F200, acceleration voltage 200 V, magnification 200,000 times). The average values obtained were used as the respective thicknesses.

(3) Carbon atom concentration, oxygen atom concentration, and silicon atom concentration in the surface layer opposite the substrate and the layer on the substrate side In the same manner as in (2) above, the cross section of the release film was observed, and the surface layer opposite the substrate and the layer on the substrate side were examined with a scanning transmission electron microscope to measure the atomic concentrations of carbon, oxygen, and silicon at three points in each layer, and the average values were taken as the atomic concentrations of each atom.

(4) Peel strength of release film and adhesive tape A polyester adhesive tape (Nitto Denko Corporation No. 31B tape, 50 mm width) was attached as an adhesive tape to the release layer side of the release film while pressing with a 5 kg roller, and after leaving it at 23° C. for 24 hours, the tape was peeled off with a tensile tester at a peel speed of 300 mm/min and a peel angle of 180°, and the peel strength was measured.

(5) Surface roughness (Sa)
The release layer side and the non-release layer side were measured using a non-contact surface/layer cross-sectional shape measuring system VertScan R5300GL-Lite-AC manufactured by Ryoka Systems Co., Ltd., with a 50x objective lens set to a measurement area of 1 mm square, in accordance with ISO 25178-3.2 (2010).

(6) Spectral absorption measured by IR measurement of release agent The release agent was measured with an IR measurement device (iS5 manufactured by Thermo Fisher Scientific, Inc., sample scan number 64 times, background scan number 64 times, resolution 8.0), and the obtained spectral absorption was evaluated as follows. The case where all of the following absorptions were confirmed was evaluated as ◯, and the case where even one was not confirmed was evaluated as ×.

Absorption of νC-H: near 2963 cm-1 Absorption of νSi-H: near 2168 cm-1 Absorption of δSi- _CH3 : near 1411 cm-1 Absorption of νSi-O-Si: near 1096 cm-1 (7) Detection by pyrolysis GC/MS measurement of release agent The release agent was measured using a gas chromatograph 7890A manufactured by Agliment Technologies (conditions: 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) and a mass spectrometer JMS-Q1050GC manufactured by JEOL Ltd. (conditions: Ionization Mode: EI+, Scan The measurement and analysis were carried out using a pyrolysis comprehensive analysis system (Pyrolyzer PY-2020iD manufactured by Frontier Labs, Inc., temperature 600°C) with a range of m/z 10.0-800.0 and a scan rate of 0.5 seconds/scan. The cases where all of the following formulas (1), (2) and (3) were detected were marked with ◯, and the cases where even one of them was not detected were marked with ×.

(n is an integer between 1 and 20)

(m represents an integer of 1 to 10)
(8) Substituents calculated from ^1H NMR spectrum The ^1H NMR spectrum of the release agent was measured using an NMR measurement device (ECA-400 manufactured by Jeol RESONANCE Co., Ltd.), and the molar ratios of the substituents Si- _CH3 , Si-H, Si-CH= _CH2 , Si-Ph, and Si- _OCH3 were calculated.

(9) Blocking Evaluation Ten sheets of the release films prepared in the examples and comparative examples were laminated so that the substrate side and the release layer side were in contact with each other, and then cut into 5 cm x 5 cm. Then, the laminate was left to stand for 24 hours at 23°C while applying a pressure of 1.5 kgf/ ^cm2 in the lamination direction. Then, the occurrence of blocking in this laminate was visually observed and evaluated according to the following criteria.

○: No blocking occurred at all.

×: Partial or complete blocking occurred.

Example 1
A primer coating liquid was prepared by mixing 3 parts by weight of BY24-846B (manufactured by Dow Corning Toray Co., Ltd., content 98% by weight) which is 3-glycidoxypropyltrimethoxysilane, 1 part by weight of BY24-846C (manufactured by Dow Corning Toray Co., Ltd., content 99% by weight) which is 3-methacryloxypropyltrimethoxysilane, and 2 parts by weight of BY24-846E (manufactured by Dow Corning Toray Co., Ltd., content 38% by weight) which is bis(ethylacetoacetate)(2,4-pentanedionate)aluminum with 50 parts by weight of toluene and 50 parts by weight of isopropyl alcohol (IPA).

Release layer coating solution 1 was prepared by mixing 8 parts by weight of X62-2888 (Shin-Etsu Chemical Co., Ltd.), an addition reaction type curable silicone resin, and 0.08 parts by weight of platinum catalyst PL-50T (Shin-Etsu Chemical Co., Ltd.), a curing agent, with 28 parts by weight of toluene and 64 parts by weight of n-heptane.

A primer coating solution was applied to a polyethylene terephthalate film having a thickness of 38 μm ("Lumilar" (registered trademark) XF60R manufactured by Toray Industries, Inc.) using a Mayer bar No. 3 so that the coating thickness after drying would be 0.05 μm, and the film was dried and cured at 100° C. for 5 seconds. Then, the release layer coating solution 1 was continuously applied to the film using a Mayer bar No. 10 so that the release layer thickness would be 0.21 μm, and the film was dried and cured at 160° C. for 20 seconds to obtain a release film having a total release layer thickness of 0.26 μm. The elastic modulus, total thickness of the release layer, peeling force, surface roughness, etc. were measured, and the results are shown in Tables 1-1, 1-2, and 2. A release film having good transportability and workability was obtained.
Example 2
Except for changing the total thickness of the release layer, release films were obtained in the same manner as in Example 1. The elastic modulus, total thickness of the release layer, peel force, surface roughness, etc. were measured, and the results are shown in Tables 1-1, 1-2, and 2. Release films with good transportability and workability were obtained.

[Examples 3 and 4]
A release film was obtained in the same manner as in Example 1, except that the total thickness of the release layer was changed and a polyethylene terephthalate film having a thickness of 38 μm ("Lumirror" (registered trademark) S28 manufactured by Toray Industries, Inc.) was used. The elastic modulus, total thickness of the release layer, peel force, surface roughness, etc. were measured, and the results are shown in Tables 1-1, 1-2, and 2. A release film with good transportability and workability was obtained.

Comparative Example 1
A release layer coating solution 2 prepared by mixing 1 part by mass of a melamine compound (RP-50 manufactured by Mitsuba Laboratory Co., Ltd., solid content 50 mass%), which is a thermosetting resin, and 9 parts by mass of a mixed solution of toluene, anon, and methanol (4.5/3.6/0.9) was used instead of the release layer coating solution 1 in Example 1, and a release film was obtained in the same manner as in Example 1, except that a polyethylene terephthalate film having a thickness of 50 μm ("Lumilar" (registered trademark) U483 manufactured by Toray Industries, Inc.) was used.

The elastic modulus, total thickness of the release layer, peeling force, surface roughness, etc. were measured, and the results are shown in Tables 1-1, 1-2, and 2. The elastic modulus, peeling force, and workability were poor.

Comparative Example 2
A release film was obtained in the same manner as in Example 1, except that the total thickness of the release layer was changed.
The modulus of elasticity, the total thickness of the release layer, the peeling force, the surface roughness, etc. were measured, and the results are shown in Tables 1-1, 1-2 and 2. When the modulus of elasticity was high, the peeling force was heavy, resulting in poor results.

Comparative Example 3
A release film was obtained in the same manner as in Comparative Example 1, except that a polyethylene terephthalate film having a thickness of 38 μm ("Lumirror" (registered trademark) XF60R manufactured by Toray Industries, Inc.) was used. The elastic modulus, total thickness of the release layer, peel force, surface roughness, and the like were measured, and the results are shown in Tables 1-1, 1-2, and 2. When the elastic modulus was high, the peel force was heavy, resulting in poor results.

Comparative Example 4
A release film was obtained in the same manner as in Example 1, except that the total thickness of the release layer was changed. The elastic modulus, the total thickness of the release layer, the peeling force, the surface roughness, and the like were measured, and the results are shown in Tables 1-1, 1-2, and 2. The elastic modulus was low and the peeling force was light, but the release layer cracked during peeling, resulting in poor workability.

As shown in Table 2, the release film according to the embodiment had a much smaller peeling force than the release film according to the comparative example. Furthermore, it was found that blocking was less likely to occur with the release film according to the embodiment.

The release film of the present invention has a small peeling force that allows stable use in processes, and therefore can be suitably used in the manufacture of various thin electronic components that make up LCD televisions, smartphones, and tablets, which are becoming thinner and thinner.

1 Surface layer opposite to substrate 2 Layer on substrate side 3 Substrate film 4 Release layer 5 Release film

Claims (9)

A release film having a release layer on at least one surface of a base film, the elastic modulus (E) of the release film measured from the release layer side using an atomic force microscope is 0.1 MPa or more and less than 1.5 MPa ;
The release layer is composed of a plurality of layers, and the total thickness (A) of the release layer is 0.05 μm or more and 2.0 μm or less . The release film according to claim 1 , wherein the ratio (B/A) of the thickness (B) of the surface layer of the plurality of layers opposite the substrate to the total thickness (A) of the release layer is 0.01 or more and 0.9 or less. 3. The release film according to claim 1, wherein a carbon atom concentration of a surface layer of the plurality of layers opposite the substrate is higher than a carbon atom concentration of a layer of the plurality of layers on the substrate side, an oxygen atom concentration of a surface layer of the plurality of layers opposite the substrate is lower than an oxygen atom concentration of a layer of the substrate side , and a silicon atom concentration of a surface layer of the plurality of layers opposite the substrate is higher than a silicon atom carbon concentration of a layer of the substrate side . The release film according to any one of claims 1 to 3, wherein the surface layer of the plurality of layers opposite the substrate has a carbon atom concentration of 40 atomic % or more and 60 atomic % or less, an oxygen atom concentration of 15 atomic % or more and 30 atomic % or less, and a silicon atom concentration of 20 atomic % or more and 40 atomic % or less. 5. The release film according to claim 1 , wherein the layer of the plurality of layers on the substrate side has a carbon atom concentration of 30 atm % or more and 60 atm % or less, an oxygen atom concentration of 25 atm % or more and 40 atm % or less, and a silicon atom concentration of 15 atm % or more and 35 atm % or less. A release film having a release layer on at least one surface of a base film, the elastic modulus (E) of the release film measured from the release layer side using an atomic force microscope is 0.1 MPa or more and less than 1.5 MPa;
A release film in which an adhesive tape is applied to the release layer, and after leaving it at 23°C for 24 hours, the peel strength between the release film and the adhesive tape when the tape is peeled off at a peel speed of 300 mm/min and a peel angle of 180° is 5 mN/50 mm or more and 80 mN/50 mm or less. A release film having a release layer on at least one surface of a base film, the elastic modulus (E) of the release film measured from the release layer side using an atomic force microscope is 0.1 MPa or more and less than 1.5 MPa;
The release film, wherein the surface roughness (Sa) of the release layer is 5 nm or more and 50 nm or less . A release film having a release layer on at least one surface of a base film, the elastic modulus (E) of the release film measured from the release layer side using an atomic force microscope is 0.1 MPa or more and less than 1.5 MPa;
A release film, wherein the ratio (E/Sa) of the elastic modulus (E) to the surface roughness (Sa) of the release layer is 0.002 MPa/nm or more and less than 0.3 MPa/nm. A method for producing a release film having a release layer on at least one surface of a base film, the method comprising the steps of applying a release agent to the base film and curing the applied release agent, wherein at least one of the release agents exhibits absorptions of at least νC-H, νSi-H, δSi- _CH3 and νSi-O-Si in a spectrum measured by IR measurement, and the following formula (1) is detected by pyrolysis gas chromatography mass spectrometry, and pyrolysates of the following general formulas (2) and (3) are detected, and the molar ratios of the substituents Si-CH3, Si-H, Si- _CH═CH2 , Si-Ph and Si-OCH3 calculated from the ^1H NMR spectrum are 93.0 or more and _99.0 or less, _0.3 or more and 3.0 or less, 0.1 or more and 2.0 or less, 0.1 or more and 1.5 or less, and 0.05 or more and 1.0 or less, respectively.

(n represents an integer of 1 to 20)

(m represents an integer of 1 to 10)

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