Reinforcing films, optical components, and electronic components

Abstract

A reinforcing film is provided that exhibits light peelability in the initial stage of attachment to a substrate, and subsequently enables a significant increase in adhesive strength, and also possesses bend recovery and bend retention capabilities. The reinforcing film comprises an adhesive layer. The adhesive layer comprises a polymer (A) and a polymer (B). The polymer (B) comprises a monomer unit having a polyorganosiloxane backbone and a (meth)acrylic monomer unit. Furthermore, the adhesive layer has a surface elastic modulus of 1 to 20 kPa at 23°C. Additionally, the glass transition temperature TB of the polymer (B) is -20°C to 5°C.

Description

Technology Field

[0001] The present invention relates to a reinforcing film, and to an optical member and an electronic member to which the reinforcing film is adhered. The present application claims priority based on Japanese Patent Application No. 2020-134188 filed on August 6, 2020, the entire contents of which are incorporated herein by reference. Background Technology

[0002] Adhesives are widely used in various applications, such as mobile phones, smartphones, tablet-type personal computers, and other electronic devices, in the form of adhesive sheets for purposes such as bonding adhered objects to each other or fixing articles to adhered objects. For example, adhesive sheets are used as reinforcing materials (reinforcing films) to impart rigidity or impact resistance to optical or electronic components constituting the above devices. Patent documents 1 and 2 can be cited as documents disclosing this type of prior art.

[0003] In addition, in recent years, portable electronic devices that can be bent or rounded have attracted attention, and the development of adhesive sheets that can be used for fixing flexible devices (typically image display devices such as organic EL or liquid crystal displays) embedded in such electronic devices is underway (Patent Documents 3 to 6).

[0004] Meanwhile, looking at the performance of adhesives, adhesive sheets have recently been proposed that exhibit low adhesive strength during the initial attachment to a substrate and then significantly increase the adhesive strength thereafter (Patent Document 7). According to adhesive sheets having such characteristics, before the increase in adhesive strength, reworkability (reworkability) is exhibited, which is useful for suppressing yield reduction caused by attachment errors or damage to the adhesive sheet, and after the increase in adhesive strength, strong adhesiveness suitable for the original purpose of use of the adhesive sheet can be exhibited. Prior art literature

[0005] Japanese Patent No. 6366199 Publication Japanese Patent No. 6366200 Publication Japanese Patent No. 6376271 Publication Japanese Patent Application Publication No. 2016-108555 Publication Japanese Patent Application Publication No. 2017-095657 Publication Japanese Patent Application Publication No. 2017-095659 Publication Japanese Patent No. 6373458 The problem to be solved

[0006] The reinforcing film can also be used in the flexible device. For example, in the manufacture of the flexible device, since the components constituting the device are often thin, it is desirable to reinforce it by attaching an adhesive sheet as a reinforcing film to prevent problems caused by deformation of the device or to improve handling. Since the flexible device can be repeatedly bent or flexed, the reinforcing film used in the flexible device is required to have the characteristic of recovering its shape normally even when repeatedly bent (flex recovery) and the characteristic of not causing problems such as peeling (flex retention). A reinforcing film having such flex recovery and flex retention can be used in various applications including flexible devices, so it is useful as it has few limitations on the scope of application.

[0007] For example, regarding an adhesive configured to exhibit low adhesion at the initial stage of application and then significantly increase adhesion thereafter, as proposed in Patent Document 7, it is desirable to possess bend recovery and bend retention when used as a reinforcing film. As one method to improve bend retention, one can consider, for instance, appropriately setting the storage modulus of the adhesive. However, in an adhesive designed to increase adhesion as described above, if the storage modulus is changed, both the initial low adhesion and the adhesion after increase are affected. Furthermore, when considering bend recovery in addition to bend retention, it is not easy to satisfy all of these characteristics. It is practically beneficial if bend recovery and bend retention can be improved for an adhesive that exhibits low adhesion at the initial stage of application and then significantly increases adhesion thereafter.

[0008] The present invention was created in consideration of the above circumstances and aims to provide a reinforcing film that exhibits light peelability in the initial stage of attachment to a substrate, can subsequently significantly increase adhesive strength, and also possesses bend recovery and bend retention capabilities. The present invention also aims to provide an optical member and an electronic member to which the reinforcing film is attached. means of solving the problem

[0009] According to the present specification, a reinforcing film having an adhesive layer is provided. The adhesive layer comprises a polymer (A) and a polymer (B). The polymer (B) comprises a monomer unit having a polyorganosiloxane backbone and a (meth)acrylic monomer unit. Additionally, the adhesive layer has a surface elastic modulus of 1 to 20 kPa at 23°C. Additionally, the glass transition temperature T of the polymer (B) B The temperature is between -20℃ and 5℃.

[0010] According to the above composition, since the adhesive layer comprises a polymer (A) and a polymer (B) comprising monomer units having a polyorganosiloxane backbone, it exhibits light peelability initially when attached to a substrate, and subsequently, it is possible to significantly increase the adhesive strength. In addition, the glass transition temperature (Tg) T of the polymer (B) B Since the temperature is -20℃ or higher, there is a tendency for excellent peelability during the initial application, and the above T B Since the temperature is 5°C or lower, there is a tendency for excellent tensile strength enhancement. In addition, the reinforcing film has bend recovery and bend retention. Specifically, a reinforcing film having a surface elasticity modulus of the adhesive layer at 23°C (23°C surface elasticity modulus) of 1 kPa or more exhibits the adhesive characteristics described above while having good bend recovery. Furthermore, since the surface elasticity modulus of the adhesive layer at 23°C is 20 kPa or lower, it exhibits the adhesive characteristics while having good bend retention, so even when used in a manner where it is repeatedly bent, problems such as peeling are unlikely to occur.

[0011] In some preferred embodiments of the technology disclosed herein (including reinforcing films, optical members, and electronic members; hereinafter the same), the adhesive layer has a bulk modulus G' at 23°C 23 This is 10 to 200 kPa. The bulk modulus G' in this range 23 According to the adhesive having [this], the adhesive strength at the beginning of application tends to be within a suitable range with excellent peelability. In addition, it has excellent processability and generally tends to be able to achieve both deformation relaxation and bending recovery at room temperature.

[0012] In some preferred embodiments, the adhesive layer has a bulk modulus G' at 80°C 80 This is 5 to 100 kPa. The bulk modulus G' in this range. 80Adhesives having [the properties] are generally easy to achieve both bend recovery and bend retention. For example, even when used under high temperature conditions of around 80°C, they may have elasticity suitable for bend recovery and adhesive retention that realizes bend retention.

[0013] In some preferred embodiments, the adhesive layer is tanδ at 80°C 80 This is 0.10 to 0.60. The above tanδ 80 (Loss in elastic modulus G at 80℃) 80 Storage modulus G' at 80℃ 80 An adhesive having ) 0.10 or higher is likely to exhibit adhesive strength suitable for maintaining flexibility. In addition, the above tanδ 80 Since this is 0.60 or less, plastic deformation of the adhesive is suppressed, making it easy to obtain good bending recovery. In addition, even when the reinforcing film is maintained in a bent state for a long time, it is easy to exert a holding force (bending holding force) that prevents peeling from the substrate.

[0014] The above polymer (A) is preferably an acrylic polymer. According to an adhesive layer comprising an acrylic polymer (A) and a polymer (B) comprising monomer units having a polyorganosiloxane backbone, the effects of the technology disclosed herein are preferably realized.

[0015] In some preferred embodiments, the content of the polymer (B) in the adhesive layer is 0.5 to 5 parts by weight per 100 parts by weight of the polymer (A). By making the amount of polymer (B) per 100 parts by weight of polymer (A) 0.5 parts by weight or more, it is easy to obtain light peelability at the initial stage of application. By making the amount of polymer (B) 5 parts by weight or less, it is easy to achieve the desired increase in adhesive strength. In addition, by keeping the amount of polymer (B) used within the above range, it is easy to achieve good bend recovery and bend retention.

[0016] In some preferred embodiments, the molar ratio ([NCO] / [OH]) of isocyanate groups and hydroxyl groups included in the adhesive layer is 0.002 to 0.03. An adhesive layer with a molar ratio ([NCO] / [OH]) of 0.002 or higher tends to have excellent flexural recovery and excellent processability. Additionally, by making the molar ratio ([NCO] / [OH]) 0.03 or lower, it tends to be easier to achieve a suitable increase in adhesive strength. Furthermore, in the adhesive layer, the isocyanate groups and hydroxyl groups may exist in a state where at least a portion thereof is chemically bonded (crosslinked). The adhesive layer may include, for example, a crosslinking agent, and in such a composition, the isocyanate groups may be, for example, part of the crosslinking agent, and the hydroxyl groups may be, for example, part of the polymer (A).

[0017] The reinforcing film disclosed herein is suitable as a reinforcing film that imparts rigidity or impact resistance to an optical member, such as a polarizer or a wave plate, during processing or transport. Accordingly, according to this specification, an optical member to which any reinforcing film disclosed herein is adhered is provided.

[0018] In addition, the reinforcing film disclosed herein is also suitable as a reinforcing film for an electronic component of a device, such as a portable electronic device. Accordingly, according to the present specification, an electronic component to which any reinforcing film disclosed herein is adhered is provided. Brief explanation of the drawing

[0019] FIG. 1 is a cross-sectional view schematically illustrating the composition of a reinforcing film according to one embodiment. FIG. 2 is a cross-sectional view schematically illustrating the configuration of a reinforcing film according to another embodiment. FIG. 3 is a cross-sectional view schematically illustrating the composition of a reinforcing film according to another embodiment. Specific details for implementing the invention

[0020] Preferred embodiments of the present invention are described below. Matters other than those specifically mentioned in this specification and matters necessary for the implementation of the present invention can be understood by those skilled in the art based on the teachings regarding the implementation of the invention described in this specification and the technical common knowledge at the time of filing. The present invention can be implemented based on the contents disclosed in this specification and the technical common knowledge in the relevant field.

[0021] In addition, in the drawings below, members and parts exhibiting the same function may be described using the same reference numerals, and redundant descriptions may be omitted or simplified. Furthermore, the embodiments described in the drawings are schematic for the purpose of clearly explaining the present invention and do not necessarily represent the exact size or scale of the actual product provided.

[0022] In addition, in this specification, the term "acrylic polymer" refers to a polymer containing monomer units derived from (meth)acrylic monomers in its polymer structure, and typically refers to a polymer containing monomer units derived from (meth)acrylic monomers in a ratio exceeding 50 weight percent. In addition, the term "(meth)acrylic monomer" refers to a monomer having at least one (meth)acryloyl group in one molecule. Here, the term "(meth)acryloyl group" comprehensively refers to both acryloyl groups and methacryloyl groups. Accordingly, the concept of (meth)acrylic monomer referred to herein may include both monomers having acryloyl groups (acrylic monomers) and monomers having methacryloyl groups (methacrylic monomers). Likewise, in this specification, "(meth)acrylic acid" comprehensively refers to acrylic acid and methacrylic acid, and "(meth)acrylate" comprehensively refers to acrylate and methacrylate, respectively.

[0023] <Example of Structure of Reinforcement Film>

[0024] The reinforcing film disclosed herein has the form of an adhesive sheet having an adhesive surface formed by an adhesive. The adhesive sheet used as a reinforcing film is composed of an adhesive layer. The reinforcing film disclosed herein may be in the form of a substrate-equipped adhesive sheet in which the adhesive layer is laminated on one or both sides of a support substrate, or it may be in the form of a substrate-free adhesive sheet that does not have a support substrate.

[0025] In addition, in this specification, the term "reinforcing film" refers to an adhesive sheet (reinforcing adhesive film) used to reinforce a substrate as described below. Since the reinforcing film can be reinforced by attaching a support material, etc., to one adhesive surface and then attaching the other adhesive surface to the substrate to be reinforced, for example, in the form of an adhesive sheet without a substrate, it is not limited to the form of an adhesive sheet with a substrate. In this respect, it is understood as a broader concept than the "reinforcing film" described below having the form of an adhesive sheet with a substrate.

[0026] The structure of a reinforcing film according to one embodiment is schematically illustrated in FIG. 1. This reinforcing film (1) is composed of a sheet-shaped support substrate (10) having a first surface (10A) and a second surface (10B), and a single-sided adhesive sheet having an adhesive layer (21) provided on the first surface (10A) side. The adhesive layer (21) is fixed to the first surface (10A) side of the support substrate (10). The reinforcing film (1) is used by attaching the adhesive layer (21) to a substrate. The reinforcing film (1) before use (i.e., before attachment to the substrate) may be a component of a reinforcing film (100) equipped with a release liner, wherein the surface (adhesive surface) (21A) of the adhesive layer (21) is in contact with a release liner (31) such that at least the side facing the adhesive layer (21) is a releaseable surface (release surface), as shown in FIG. 1. As for the release liner (31), it is preferable to use one configured such that the one side becomes a release surface by forming a release layer by a release treatment agent on one side of a sheet-shaped substrate (liner substrate), for example. Alternatively, the release liner (31) may be omitted, and a support substrate (10) having a second surface (10B) as a release surface may be used, and the reinforcing film (1) may be wound so that the adhesive surface (21A) comes into contact with the second surface (10B) of the support substrate (10) (roll form). When attaching the reinforcing film (1) to a substrate, the release liner (31) or the second surface (10B) of the support substrate (10) is peeled off from the adhesive surface (21A), and the exposed adhesive surface (21A) is pressed against the substrate.

[0027] The structure of a reinforcing film according to another embodiment is schematically illustrated in FIG. 2. This reinforcing film (2) is composed of a double-sided adhesive sheet having a sheet-shaped support substrate (10) having a first surface (10A) and a second surface (10B), an adhesive layer (21) provided on the first surface (10A) side, and an adhesive layer (22) provided on the second surface (10B) side. The adhesive layer (first adhesive layer) (21) is fixed to the first surface (10A) of the support substrate (10), and the adhesive layer (second adhesive layer) (22) is fixed to the second surface (10B) of the support substrate (10). The reinforcing film (2) is used by attaching the adhesive layers (21, 22) to other locations on the substrate. The location where the adhesive layer (21, 22) is attached may be a location of each other member, or a location within a single member. The reinforcing film (2) before use may be a component of a reinforcing film (200) equipped with a release liner, in which the surface (first adhesive surface) (21A) of the adhesive layer (21) and the surface (second adhesive surface) (22A) of the adhesive layer (22) are in contact with a release liner (31, 32) such that at least the side facing the adhesive layer (21, 22) is a release surface. As for the release liner (31, 32), it is preferable to use one configured such that the side becomes a release surface by forming a release layer with a release treatment agent on one side of a sheet-shaped substrate (liner substrate). Alternatively, the peeling liner (32) may be omitted, and a peeling liner (31) having both sides as peeling surfaces may be used, and the reinforcing film (2) may be overlapped and wound in a spiral shape so that the second adhesive surface (22A) is in contact with the back surface of the peeling liner (31), thereby forming a reinforcing film equipped with a peeling liner in a roll shape.

[0028] The structure of a reinforcing film according to another embodiment is schematically illustrated in FIG. 3. This reinforcing film (3) is composed of a double-sided adhesive sheet made of a non-material adhesive layer (21). The reinforcing film (3) is used by attaching a first adhesive surface (21A) formed by one surface (first surface) of the adhesive layer (21) and a second adhesive surface (21B) formed by the other surface (second surface) of the adhesive layer (21) to different locations on the substrate. Before use, the reinforcing film (3) may be a component of a reinforcing film (300) equipped with a release liner, in which the first adhesive surface (21A) and the second adhesive surface (21B) are in contact with a release liner (31, 32), in which at least the side facing the adhesive layer (21) is a release surface. Alternatively, the peeling liner (32) may be omitted, and a peeling liner (31) having both sides as peeling surfaces may be used, and the reinforcing film (3) may be overlapped and wound in a spiral shape so that the second adhesive surface (21B) is in contact with the back surface of the peeling liner (31), thereby forming a reinforcing film equipped with a peeling liner in a roll shape.

[0029] In addition, the reinforcing film may be in the form of a roll or a single leaf, or it may be cut, punched, or processed into a suitable shape depending on the application or mode of use. The adhesive layer in the technology disclosed herein is typically formed continuously, but is not limited thereto and may be formed in a regular or random pattern, such as a dot shape or a stripe shape.

[0030] <Adhesive layer>

[0031] The reinforcing film disclosed herein comprises an adhesive layer comprising a polymer (A) and a polymer (B). Such an adhesive layer may be formed from an adhesive composition containing a polymer (A), which is a complete or partial polymer of monomer raw material A, and a polymer (B). The form of the adhesive composition is not particularly limited and may be of various forms, such as, for example, a solvent type, a water-dispersible type, a hot-melt type, or an active energy beam curing type (e.g., a photocuring type).

[0032] (Surface modulus at 23℃)

[0033] The adhesive layer disclosed herein is characterized by the fact that the surface elasticity modulus at 23°C of its surface (adhesive surface) is within the range of 1 to 20 kPa. By having the 23°C surface elasticity modulus of 1 kPa or more, it is possible to achieve adhesive properties based on the inclusion of polymer (A) and polymer (B) while having good bending recovery properties. Additionally, by having the surface elasticity modulus of 20 kPa or less, it is possible to achieve adhesive properties while exhibiting good bending retention.

[0034] From the perspective of improving flexural recovery, the surface elastic modulus at 23°C is preferably 2 kPa or more, more preferably 3 kPa or more, and even more preferably 4 kPa or more (e.g., 5 kPa or more), and may be 8 kPa or more, 10 kPa or more, or 12 kPa or more (e.g., 14 kPa or more). As the surface elastic modulus increases, the initial peelability tends to be excellent. In addition, from the perspective of achieving both good flexural recovery and flexural retention while preferably exhibiting an increase in adhesive strength, the surface elastic modulus at 23°C is suitable to be 15 kPa or less, preferably 12 kPa or less, more preferably 9 kPa or less, and even more preferably 7 kPa or less (e.g., 6 kPa or less), and may be 4 kPa or less.

[0035] The 23°C surface elastic modulus of the adhesive layer can be controlled by the type or characteristics (molecular weight, glass transition temperature, molecular structure, etc.) of the polymer (A), the type (chemical structure, etc.) or characteristics (molecular weight, glass transition temperature, etc.) of the polymer (B), the amount used, the type or amount of the crosslinking agent, etc. The 23°C surface elastic modulus of the adhesive layer is measured by the method described in the examples described below.

[0036] (23℃ Bulk modulus of elasticity G' 23 )

[0037] Bulk modulus G' of the adhesive layer at 23°C 23 (23℃ Bulk modulus of elasticity G' 23 ) is appropriately set within a range satisfying the above 23°C surface modulus range, and is not limited to a specific range. In some embodiments, the 23°C bulk modulus G' of the adhesive layer 23 It is appropriate to make the value 10 kPa or higher. The above bulk modulus G' 23 By making it greater than a predetermined value, the initial adhesive strength is likely to fall within a suitable range with excellent peelability. In addition, it exhibits excellent processability and generally tends to have excellent bending recovery at room temperature. The above bulk modulus G' 23 It is preferably 15 kPa or more, more preferably 20 kPa or more, even more preferably 25 kPa or more, and particularly preferably 30 kPa or more. In some other embodiments, the bulk modulus G' 23 It may be 50 kPa or more, 80 kPa or more, or 100 kPa or more.

[0038] In some embodiments, the bulk modulus G' of the adhesive layer at 23°C 23 It is appropriate to keep it at 200 kPa or less. The above bulk modulus G' 23 Adhesives with a value below this predetermined value generally tend to exhibit excellent deformation relaxation in the room temperature range and are also prone to exhibiting an increase in adhesive strength. The above bulk modulus G' 23It is preferably 150 kPa or less, more preferably 90 kPa or less. In some preferred embodiments, the bulk modulus G' 23 It may be 60 kPa or less, or 40 kPa or less (e.g., 35 kPa or less).

[0039] (80℃ Bulk modulus of elasticity G' 80 )

[0040] Bulk modulus G' of the adhesive layer at 80°C 80 (80℃ Bulk modulus of elasticity G' 80 ) is appropriately set within a range satisfying the above 23°C surface modulus range, and is not limited to a specific range. In some embodiments, the 80°C bulk modulus G' of the adhesive layer 80 It is preferable that the value be 5 kPa or higher. The above bulk modulus G' 80 By making it greater than a predetermined value, flexural recovery is generally easily improved, and even when used under high-temperature conditions, it can have elasticity suitable for flexural recovery. In some preferred embodiments, the bulk modulus G' 80 It may be 7 kPa or more, 9 kPa or more, or 10 kPa or more. In some other embodiments, the bulk modulus G' 80 It may be 15 kPa or more, 30 kPa or more, or 50 kPa or more.

[0041] In some embodiments, the bulk modulus G' of the adhesive layer at 80°C 80 It is appropriate to keep it at 100 kPa or less. The above bulk modulus G' 80 By limiting it to a value below a predetermined value, it is generally easy to obtain good flexural retention and easy to achieve a balance between flexural recovery and flexural retention. For example, in various environments including high-temperature conditions, it is possible to have elasticity suitable for flexural recovery and adhesive retention that realizes flexural retention. The above bulk elastic modulus G' 80The value is preferably 90 kPa or less, and more preferably 60 kPa or less. In some embodiments, the bulk modulus G' 80 It may be 20 kPa or less, 16 kPa or less, or 14 kPa or less (e.g., 12 kPa or less).

[0042] (80℃ tanδ 80 )

[0043] tanδ of the adhesive layer at 80°C 80 (80℃ tanδ 80 ) is appropriately set within a range satisfying the above 23°C surface elastic modulus range, and is not limited to a specific range. In some embodiments, the 80°C tanδ of the adhesive layer 80 It is suitable for the value to be 0.10 or higher. The above tanδ 80 The higher this value, the easier it is for the adhesive to exert adhesive strength suitable for maintaining flexibility. The above tanδ 80 The value is preferably 0.20 or higher. In some preferred embodiments, the tanδ 80 It may be 0.30 or higher, 0.40 or higher, or 0.45 or higher.

[0044] In some embodiments, the 80°C tanδ of the adhesive layer 80 It is preferable that the value be 0.60 or less. The above tanδ 80 Since this is 0.60 or less, plastic deformation of the adhesive is suppressed, making it easy to obtain good bending recovery. In addition, even when the reinforcing film is maintained in a bent state for a long time, it is easy to exert holding power that prevents peeling from the substrate. Furthermore, the increase in adhesive strength is also easily within an appropriate range. The above 80°C tanδ 80 The value may be 0.55 or less. In some other embodiments, the above 80°C tanδ 80 It may be 0.50 or less, or 0.35 or less.

[0045] Bulk elastic modulus G' of the adhesive layer at 23°C 23, 80℃ Bulk elastic modulus G' 80 and 80℃ tanδ 80 The bulk modulus G' of the adhesive layer at 23°C can be controlled by the type or characteristics (molecular weight, glass transition temperature, molecular structure, etc.) of the polymer (A), the type (chemical structure, etc.) or characteristics (molecular weight, glass transition temperature, etc.) of the polymer (B), the amount used, the type or amount of the crosslinking agent, etc. 23 , 80℃ Bulk elastic modulus G' 80 and 80℃ tanδ 80 Silver is measured by the method described in the embodiments below.

[0046] (Polymer(A))

[0047] As the polymer (A), one or more types of various polymers that exhibit rubber elasticity in the room temperature range, such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluorine polymers known in the field of adhesives, may be used. In the reinforcing film disclosed herein, the polymer (A) is typically a main component of the polymer component included in the adhesive layer, i.e., a component that accounts for more than 50 weight%, and may be, for example, a component that accounts for more than 75 weight% of the polymer component. In some embodiments, the polymer (A) is a component that accounts for more than 50 weight% of the entire adhesive layer, and may be a component that accounts for more than 70 weight%, or a component that accounts for more than 80 weight%, or a component that accounts for more than 90 weight%, or a component that accounts for more than 95 weight% (for example, more than 97 weight%).

[0048] Glass transition temperature T of polymer (A) A The reinforcing film disclosed herein is not particularly limited and can be selected to obtain desirable characteristics. In some embodiments, T AA polymer (A) with a temperature below 0°C may be preferably employed. Since an adhesive containing such a polymer (A) exhibits suitable fluidity (e.g., the mobility of polymer chains included in the adhesive), it is suitable for realizing a reinforcing film in which the adhesive strength increases above a predetermined value upon heating. The reinforcing film disclosed herein is T A It can be preferably implemented using a polymer (A) with a temperature of less than -10°C, less than -20°C, less than -30°C, or less than -35°C. In some embodiments, T A It may be below -40℃ or below -50℃. In some preferred embodiments, T A is -55°C or lower, more preferably -58°C or lower, even more preferably -62°C or lower, and may be -65°C or lower (e.g., -66°C or lower). A The lower limit of is not specifically restricted. In terms of the ease of material availability or the improvement of the cohesiveness of the adhesive layer, typically, T A A polymer (A) having a temperature of -80°C or higher and -70°C or higher may be preferably employed. In some embodiments, T A For example, it may be -63℃ or higher, -55℃ or higher, -50℃ or higher, or -45℃ or higher.

[0049] In this specification, the glass transition temperature (Tg) of a polymer (e.g., the glass transition temperature of polymer (A), polymer (B) described below, etc.) refers to a nominal value stated in literature or catalogs, or a Tg obtained by the Fox formula based on the composition of the monomer raw materials used in the preparation of the said polymer. The Fox formula is a relationship between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer formed by homopolymerizing each of the monomers constituting the said copolymer, as described below.

[0050] 1 / Tg=Σ(Wi / Tgi)

[0051] In the above Fox formula, Tg represents the glass transition temperature of the copolymer (unit: K), Wi represents the weight fraction of monomer i in the copolymer (copolymerization ratio based on weight), and Tgi represents the glass transition temperature of the homopolymer of monomer i (unit: K). If the polymer subject to Tg specification is a homopolymer, the Tg of the homopolymer and the Tg of the polymer subject to specification are the same.

[0052] For the glass transition temperature of the homopolymer used to calculate Tg, the value listed in known data shall be used. Specifically, numerical values ​​are exemplified in the “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc., 1989). For monomers for which multiple types of values ​​are listed in the above Polymer Handbook, the highest value shall be adopted.

[0053] For the glass transition temperature of homopolymers of monomers not listed in the above Polymer Handbook, the value obtained by the following measurement method shall be used.

[0054] Specifically, 100 parts by weight of monomer, 0.2 parts by weight of 2,2'-azobisisobutyronitrile, and 200 parts by weight of ethyl acetate as a polymerization solvent are introduced into a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, and the mixture is stirred for 1 hour while circulating nitrogen gas. After removing oxygen from the polymerization system in this way, the temperature is raised to 63°C and the reaction is carried out for 10 hours. Subsequently, the mixture is cooled to room temperature to obtain a homopolymer solution with a solid content concentration of 33% by weight. Then, this homopolymer solution is flexibly coated onto a release liner and dried to produce a test sample (sheet-shaped homopolymer) with a thickness of about 2 mm. This test sample is punched into a disc shape with a diameter of 7.9 mm, placed between parallel plates, and viscoelasticity is measured by a shear mode with a heating rate of 5°C / min and a temperature range of -70°C to 150°C while applying shear deformation at a frequency of 1 Hz using a viscoelasticity tester (manufactured by TA Instruments Japan, model name "ARES"), and the temperature corresponding to the peak top temperature of tanδ is set as the Tg of the homopolymer.

[0055] Although not specifically limited, the weight-average molecular weight (Mw) of the polymer (A) is typically approximately 20×10 4 It is suitable for the above. With such a polymer (A) of Mw, it is easy to obtain an adhesive exhibiting good cohesiveness. In some preferred embodiments, with regard to obtaining higher cohesiveness, the Mw of the polymer (A) is, for example, 30×10 4 It can be more than 40×10 4 It can be more than 50×10 4 It can be more than 60×10 4 It can be more than 80×10 4 It may be greater than or equal to 10. Also, the Mw of the polymer (A) is typically approximately 500 × 10 4It is suitable for the Mw to be less than or equal to this. Since a polymer (A) with such an Mw is easy to form an adhesive exhibiting appropriate fluidity (mobility of polymer chains), it is suitable for realizing a reinforcing film with low initial adhesion and a large increase in adhesion. It is also desirable that the Mw of the polymer (A) is not too high, from the perspective of improving compatibility with the polymer (B). In some preferred embodiments, the Mw of the polymer (A) is, for example, 250 × 10 4 It may be less than or equal to 200×10 4 It may be less than or equal to 150×10 4 It may be less than or equal to 100×10 4 It may be less than or equal to 70×10 4 It is acceptable to do the following.

[0056] In addition, in this specification, the Mw of polymer (A) and polymer (B) described below can be obtained by converting to polystyrene by gel permeation chromatography (GPC). More specifically, the Mw can be measured in accordance with the method and conditions described in the examples described below.

[0057] As the polymer (A) in the reinforcing film disclosed herein, an acrylic polymer may be preferably adopted. When an acrylic polymer is used as the polymer (A), it tends to be easier to obtain good compatibility with the polymer (B). Good compatibility between the polymer (A) and the polymer (B) is desirable because it can contribute to reducing the initial adhesive strength and improving the adhesive strength after heating by improving the mobility of the polymer (B) within the adhesive layer. Furthermore, acrylic polymers, which have a high degree of freedom in molecular design, are suitable as adhesive materials that can improve adhesive properties, bend recovery, and bend retention in a good balance.

[0058] The acrylic polymer may be, for example, a polymer containing 50 weight percent or more of monomer units derived from (meth)acrylate alkyl esters, that is, a polymer in which 50 weight percent or more of the total amount of the monomer component (monomer raw material A) for preparing said acrylic polymer is (meth)acrylate alkyl ester. As for the (meth)acrylate alkyl ester, having 1 to 20 carbon atoms (i.e., C 1-20 (of) An alkyl ester of (meth)acrylic acid having a straight-chain or branched-chain alkyl group may be preferably used. In terms of ease of balancing properties, (meth)acrylic acid C among monomer raw material A 1-20 The proportion of the alkyl ester may, for example, be 50 weight% or more, or 60 weight% or more. In some preferred embodiments, (meth)acrylic acid C in monomer raw material A 1-20 The proportion of alkyl ester is 70% by weight or more, more preferably 80% by weight or more, even more preferably 85% by weight or more, and particularly preferably 90% by weight or more. By using an acrylic polymer with such a monomer composition, it is easy to obtain an adhesive that achieves a good balance of increased tackiness, flex recovery, and flex retention. Among monomer raw material A, (meth)acrylic acid C 1-20 The proportion of alkyl ester may, for example, be 99.9% by weight or less, 98% by weight or less, or 95% by weight or less. In some embodiments, (meth)acrylic acid C in monomer raw material A 1-20 The proportion of alkyl ester may be, for example, 90% by weight or less, 85% by weight or less, or 80% by weight or less.

[0059] (Met)acrylic acid C 1-20Non-limiting specific examples of alkyl esters include (meth)acrylate methyl, (meth)acrylate ethyl, (meth)acrylate propyl, (meth)acrylate isopropyl, (meth)acrylate n-butyl, (meth)acrylate isobutyl, (meth)acrylate s-butyl, (meth)acrylate t-butyl, (meth)acrylate pentyl, (meth)acrylate isopentyl, (meth)acrylate hexyl, (meth)acrylate heptyl, (meth)acrylate octyl, (meth)acrylate 2-ethylhexyl, (meth)acrylate isooctyl, (meth)acrylate nonyl, (meth)acrylate isononyl, (meth)acrylate decyl, (meth)acrylate isodecyl, (meth)acrylate undecyl, (meth)acrylate dodecyl. Examples include tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, etc.

[0060] At least one of these (meth)acrylic acid C 1-18 It is preferable to use an alkyl ester, and at least (meth)acrylic acid C 1-14 It is more preferable to use alkyl esters. In some embodiments, the acrylic polymer is (meth)acrylic acid C 4-12 Alkyl ester (preferably acrylic acid C) 4-10 Alkyl esters, e.g., acrylic acid C 6-10 It may contain at least one selected from alkyl esters as a monomer unit. For example, an acrylic polymer comprising one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA) is preferred, and an acrylic polymer comprising at least 2EHA is particularly preferred.

[0061] In some preferred embodiments, acrylic acid C in monomer raw material A for preparing an acrylic polymer 6-10 Alkyl ester (suitably acrylic acid C 8-9The proportion of alkyl ester (typically 2EHA) is 70 wt% or more, more preferably 80 wt% or more, even more preferably 85 wt% or more, and particularly preferably 90 wt% or more. An acrylic polymer of such a monomer composition is particularly suitable for realizing the effects of the technique disclosed herein. In addition, acrylic acid C in monomer raw material A 6-10 Alkyl ester (suitably acrylic acid C 8-9 The proportion of alkyl ester (typically 2EHA) may be, for example, 99.9% by weight or less, 98% by weight or less from the viewpoint of initial low tack, flexural recovery, etc., and 95% by weight or less.

[0062] In addition, in some preferred embodiments, among monomer raw material A for preparing an acrylic polymer, (meth)acrylic acid C 1-3 It is desirable that the proportion of alkyl esters (e.g., C1 alkyl esters of (meth)acrylic acid, typically methyl methacrylate (MMA)) be limited. (meth)acrylic acid C 1-3 Alkyl esters (e.g., C1 alkyl esters of (meth)acrylic acid, typically MMA) tend to have a relatively high Tg, so adhesives containing acrylic polymers using the above monomer components tend to have high cohesiveness. (meth)acrylic acid C 1-3 By limiting the amount of alkyl ester used, the cohesive force of the adhesive can be appropriately reduced, thereby preferably realizing an elastic modulus (typically surface elastic modulus) suitable for achieving both increased flexural retention and adhesive strength. In this regard, (meth)acrylic acid C among the monomer raw material A 1-3 The proportion of alkyl ester (e.g., (meth)acrylic acid C1 alkyl ester, typically MMA) is suitably 8% by weight or less, preferably 6% by weight or less, more preferably 3% by weight or less, and even more preferably 1% by weight or less (e.g., 0 to 0.3% by weight).

[0063] Monomer raw material A may include, together with the (meth)acrylate alkyl ester as the main component, other monomers capable of copolymerizing with the (meth)acrylate alkyl ester (copolymerizable monomers) as necessary. As copolymerizable monomers, monomers having polar groups (e.g., carboxyl groups, hydroxyl groups, nitrogen-containing rings, etc.) may be suitably used. Monomers having polar groups may be helpful in introducing crosslinking points into acrylic polymers or increasing the cohesive strength of acrylic polymers. One type of copolymerizable monomer may be used alone or in combination of two or more types.

[0064] Non-limiting specific examples of copolymerizable monomers include the following.

[0065] Hydroxyl group-containing monomers: e.g., (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 2-hydroxybutyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 4-hydroxybutyl, (meth)acrylic acid 6-hydroxyhexyl, (meth)acrylic acid 8-hydroxyoctyl, (meth)acrylic acid 10-hydroxydecyl, (meth)acrylic acid 12-hydroxylauryl, (4-hydroxymethylcyclohexyl)methyl(meth)acrylate, etc. (meth)acrylic acid hydroxyalkyl, etc.

[0066] Monomers having a nitrogen atom-containing ring: e.g., N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylmorpholine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazine-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisooxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine, etc.;

[0067] For example, monomers having a succinimide backbone, such as N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, N-(meth)acryloyl-8-oxyhexamethylene succinimide;

[0068] For example, maleimides such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.; and,

[0069] For example, itaconimides such as N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexyl itaconimide, N-lauryl itaconimide, etc.

[0070] Carboxylic group-containing monomers: e.g., acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc.

[0071] Acid anhydride-containing monomers: e.g., maleic anhydride, itaconic anhydride.

[0072] Epoxy group-containing monomers: e.g., epoxy group-containing acrylates such as (meth)acrylic acid glycidyl or (meth)acrylic acid-2-ethylglycidyl ether, allylglycidyl ether, (meth)acrylic acid glycidyl ether, etc.

[0073] Cyano group-containing monomers: e.g., acrylonitrile, methacrylonitrile, etc.

[0074] Monomers containing isocyanate groups: e.g., 2-isocyanatoethyl (meth)acrylate, etc.

[0075] Amide group-containing monomers: e.g., (meth)acrylamide; N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide; N-alkyl(meth)acrylamides such as N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, Nn-butyl(meth)acrylamide; N-vinylcarboxylic acid amides such as N-vinylacetamide; N-hydroxyalkyl(meth)acrylamides, such as monomers having hydroxyl groups and amide groups, for example, N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide; monomers having alkoxy groups and amide groups, for example, N-alkoxyalkyl(meth)acrylamides, such as N-methoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide; In addition, N,N-dimethylaminopropyl(meth)acrylamide, etc.

[0076] (Met)acrylate aminoalkyls: e.g., (meth)acrylate aminoethyl, (meth)acrylate N,N-dimethylaminoethyl, (meth)acrylate N,N-diethylaminoethyl, (meth)acrylate t-butylaminoethyl.

[0077] Alkoxy group-containing monomers: e.g., (meth)acrylate 2-methoxyethyl, (meth)acrylate 3-methoxypropyl, (meth)acrylate 2-ethoxyethyl, (meth)acrylate propoxyethyl, (meth)acrylate butoxyethyl, (meth)acrylate ethoxypropyl, etc. (meth)acrylate alkoxyalkyl groups; (meth)acrylate alkoxyalkylene glycols, (meth)acrylate methoxyethylene glycol, (meth)acrylate methoxypolypropylene glycol, etc. (meth)acrylate alkoxyalkylene glycols.

[0078] Monomers containing a sulfonic acid group or a phosphate group: e.g., styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl(meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethylacryloylphosphate, etc.

[0079] (Meth)acrylic acid esters having a cyclocyclic hydrocarbon group: e.g., cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclofentanyl (meth)acrylate, etc.

[0080] (Meth)acrylic acid esters having an aromatic hydrocarbon group: e.g., phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, etc.

[0081] Vinyl ethers: for example, vinylalkyl ethers such as methyl vinyl ether or ethyl vinyl ether.

[0082] Vinyl esters: e.g., vinyl acetate, vinyl propionate, etc.

[0083] Aromatic vinyl compounds: e.g., styrene, α-methylstyrene, vinyltoluene, etc.

[0084] Olefins: e.g., ethylene, butadiene, isoprene, isobutylene, etc.

[0085] In addition, heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen-atom-containing (meth)acrylates such as vinyl chloride or fluorine-atom-containing (meth)acrylates, silicon-atom-containing (meth)acrylates such as silicon (meth)acrylates, and (meth)acrylic acid esters obtained from terpene compound derivative alcohols.

[0086] When using such a copolymer monomer, the amount used is not particularly limited, but it is generally appropriate to use at least 0.01% by weight of monomer raw material A. From the perspective of better exhibiting the effects of using the copolymer monomer, the amount of copolymer monomer used may be at least 0.1% by weight of monomer raw material A or at least 1% by weight. In some preferred embodiments, the content of copolymer monomer in monomer raw material A is at least 3% by weight, more preferably at least 5% by weight, and even more preferably at least 7% by weight (e.g., at least 8% by weight). As the amount of copolymer monomer used increases, the cohesiveness increases, and the bending recovery tends to improve. In addition, the amount of copolymer monomer used may be at least 50% by weight of monomer raw material A, and it is preferable to use at least 30% by weight. By doing so, the cohesiveness of the adhesive is prevented from becoming too high, thereby improving the tackiness at room temperature (25°C). In some preferred embodiments, the amount of copolymerized monomer used is 20% by weight or less of monomer raw material A, more preferably 15% by weight or less (e.g. 12% by weight or less), and may be 10% by weight or less. By limiting the amount of copolymerized monomer used, the cohesive force of the adhesive is reduced, and the elastic modulus (typically surface elastic modulus) is within a suitable range, making it easy to obtain excellent flexural retention and easy to realize an increase in adhesive strength.

[0087] In some embodiments, monomer raw material A may include a monomer having a nitrogen atom-containing ring. By using a monomer having a nitrogen atom-containing ring, the cohesiveness or polarity of the adhesive can be adjusted, thereby suitably improving the adhesive strength after heating. By including a monomer having a nitrogen atom-containing ring in monomer raw material A, the compatibility between the polymer (A) formed from the monomer raw material A and the polymer (B) tends to improve. As a result, it becomes easier to obtain a reinforcing film that can significantly increase adhesive strength by heating.

[0088] Monomers having a nitrogen atom-containing ring may be appropriately selected from the examples above, for instance, and used either alone or in combination of two or more types. In some embodiments, monomer raw material A preferably contains at least one monomer selected from the group consisting of N-vinyl cyclic amides and cyclic amides having a (meth)acryloyl group, as a monomer having a nitrogen atom-containing ring.

[0089] Specific examples of N-vinyl cyclic amides include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazine-2-one, N-vinyl-3,5-morpholindione, etc. Particularly preferably, N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam.

[0090] Specific examples of cyclic amides having a (meth)acryloyl group include N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylmorpholine, etc. A suitable example is N-acryloylmorpholine (ACMO).

[0091] The amount of monomer having a nitrogen atom-containing ring is not particularly limited, and is typically suitable to be 40% by weight or less of monomer raw material A, 30% by weight or less, 20% by weight or less, or 10% by weight or less. In some preferred embodiments, with regard to lowering the elastic modulus (typically surface elastic modulus) by lowering the cohesive force, the content of the monomer having a nitrogen atom-containing ring in monomer raw material A is 7% by weight or less, more preferably 5% by weight or less, and even more preferably 3% by weight or less (e.g., 1.5% by weight or less). In addition, the amount of monomer having a nitrogen atom-containing ring is typically suitable to be 0.01% by weight or more of monomer raw material A (preferably 0.1% by weight or more, e.g., 0.5% by weight or more). In terms of obtaining appropriate cohesive force and elastic modulus, in some embodiments, the amount of monomer having a nitrogen atom-containing ring used may be 0.8% by weight or more of monomer raw material A, or 1.0% by weight or more.

[0092] In some preferred embodiments, monomer raw material A comprises a hydroxyl group-containing monomer. By using a hydroxyl group-containing monomer, the cohesiveness, polarity, and further elastic modulus (typically surface elastic modulus) of the adhesive can be adjusted, thereby preferably realizing the effects of the technique disclosed herein. In addition, the hydroxyl group-containing monomer provides reaction sites with a crosslinking agent (e.g., an isocyanate-based crosslinking agent) described below, and the cohesiveness of the adhesive can be increased through a crosslinking reaction.

[0093] As hydroxyl group-containing monomers, (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 4-hydroxybutyl, (meth)acrylic acid 6-hydroxyhexyl, N-(2-hydroxyethyl)(meth)acrylamide, etc., can be suitably used. Among these, preferred examples include 2-hydroxyethyl acrylic acid (HEA), 4-hydroxybutyl acrylic acid (4HBA), and N-(2-hydroxyethyl)acrylamide (HEAA). 4HBA is particularly preferred from the perspective of obtaining cohesive strength suitable for flexural recovery and flexural retention.

[0094] The amount of hydroxyl group-containing monomer used is not particularly limited, and typically, it is suitable to be 40% by weight or less of monomer raw material A, or 30% by weight or less, or 20% by weight or less. In some preferred embodiments, from the view of reducing cohesiveness, and furthermore elastic modulus (typically surface elastic modulus), the content of the hydroxyl group-containing monomer in monomer raw material A is 15% by weight or less, and more preferably 12% by weight or less (e.g., 10% by weight or less). By limiting the amount of hydroxyl group-containing monomer used, the mobility of the polymer (B) within the adhesive layer is improved, making it easier to realize an increase in adhesive strength. In some other embodiments, the content of the hydroxyl group-containing monomer may be 5% by weight or less of monomer raw material A. In addition, the amount of hydroxyl group-containing monomer used is suitable to be 0.01% by weight or more of monomer raw material A (preferably 0.1% by weight or more, for example 0.5% by weight or more). In some preferred embodiments, for obtaining suitable cohesive force and elastic modulus, the amount of hydroxyl group-containing monomer used is 1% by weight or more of monomer raw material A, more preferably 3% by weight or more, even more preferably 5% by weight or more, and particularly preferably 7% by weight or more (for example 8% by weight or more).

[0095] In some embodiments, a monomer having a nitrogen atom-containing ring and a monomer containing a hydroxyl group may be used in combination as copolymer monomers. In this case, the total amount of the monomer having a nitrogen atom-containing ring and the monomer containing a hydroxyl group may be, for example, 0.1% by weight or more of monomer raw material A, preferably 1% by weight or more, more preferably 3% by weight or more, even more preferably 5% by weight or more, particularly preferably 7% by weight or more (e.g., 9% by weight or more), and may be 10% by weight or more, 15% by weight or more, 20% by weight or more, or 25% by weight or more. Additionally, the total amount of the monomer having a nitrogen atom-containing ring and the monomer containing a hydroxyl group may be, for example, 50% by weight or less of monomer raw material A, and it is preferable to be 30% by weight or less. In some preferred embodiments, the total amount of the monomer having a nitrogen atom-containing ring and the monomer containing a hydroxyl group is 20% by weight or less of the monomer raw material A, and more preferably 15% by weight or less (e.g., 12% by weight or less).

[0096] Monomer raw material A is nitrogen In an embodiment comprising a combination of a monomer having an atom-containing ring and a hydroxyl group-containing monomer, the content of the monomer having a nitrogen atom-containing ring in the monomer raw material A (W N ) and hydroxyl group-containing monomer content (W OH The relationship (based on weight) is not specifically limited. W N / W OH ...is, for example, 0.01 or higher, usually 0.05 or higher is suitable, 0.10 or higher, or 0.12 or higher. Also, W N / W OH For example, it may be 10 or less, usually 1 or less is suitable, preferably 0.50 or less, may be 0.30 or less, may be 0.20 or less, and may be 0.15 or less.

[0097] In some embodiments, monomer raw material A preferably does not contain a monomer having a polyorganosiloxane backbone (monomer S1) which is preferably used as a component of monomer raw material B described below, or the content of said monomer is less than 10% by weight of monomer raw material A (more preferably less than 5% by weight, for example less than 2% by weight). With monomer raw material A having such a composition, a reinforcing film that suitably combines initial reworkability with strong adhesion after increased tackiness can be suitably realized. For the same reason, in some other embodiments, monomer raw material A preferably does not contain monomer S1, or if it contains monomer S1, the content (by weight) is lower than the content of monomer S1 in monomer raw material B.

[0098] The method for obtaining the polymer (A) is not particularly limited, and various polymerization methods such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization can be appropriately employed. In some embodiments, solution polymerization can be preferably employed. The polymerization temperature when performing solution polymerization can be appropriately selected depending on the type of monomer and solvent used, the type of polymerization initiator, etc., and can be, for example, 20°C to 170°C (typically 40°C to 140°C).

[0099] The initiator used for polymerization can be appropriately selected from conventionally known thermal polymerization initiators or photopolymerization initiators, depending on the polymerization method. The polymerization initiator can be used as a single type or in combination of two or more types.

[0100] As thermal polymerization initiators, for example, azo-based polymerization initiators (e.g., 2,2'-azobis-isobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionic acid)dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobis-isovaleronitrile, 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazoline-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine)disulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine)dihydrochloride, etc.); persulfates such as potassium persulfate; Examples include peroxide-based polymerization initiators (e.g., dibenzoyl peroxide, t-butyl permaleate, lauroyl peroxide, etc.); redox-based polymerization initiators, etc. The amount of thermal polymerization initiator used is not particularly limited, but can be in an amount within the range of 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, per 100 parts by weight of monomer component (monomer raw material A) used in the preparation of polymer (A).

[0101] As a photopolymerization initiator, although not particularly limited, examples include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, etc. The amount of photopolymerization initiator used is not particularly limited, but may be, for example, in an amount within the range of 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, per 100 parts by weight of monomer raw material A.

[0102] In some embodiments, the polymer (A) may be included in an adhesive composition for forming an adhesive layer in the form of a partial polymer (polymer syrup) obtained by polymerizing a portion of the monomer component by irradiating a mixture of monomer raw material A, as described above, with a polymerization initiator, with ultraviolet (UV) light. An adhesive composition containing such a polymer syrup may be applied to a predetermined substrate, and the polymerization may be completed by irradiating with ultraviolet light. That is, the polymer syrup may be identified as a precursor of the polymer (A). The adhesive layer disclosed herein may be formed, for example, using an adhesive composition containing the polymer syrup and the polymer (B).

[0103] (Polymer(B))

[0104] The polymer (B) in the technology disclosed herein is a polymer of a monomer having a polyorganosiloxane backbone (hereinafter also referred to as "monomer S1") and a monomer component (monomer raw material B) comprising a (meth)acrylic monomer. The polymer (B) may be a copolymer of monomer S1 and a (meth)acrylic monomer. Polymer (B) may be used as a single type or in combination of two or more types. Polymer (B) may function as an adhesion strength increase retardant that suppresses the initial adhesion strength to a substrate due to the low polarity and mobility of the polyorganosiloxane structure derived from monomer S1, and also increases the adhesion strength to a substrate upon heating. As monomer S1, any monomer containing a polyorganosiloxane backbone may be used. Monomer S1, due to the low polarity derived from its structure, promotes the localization of the polymer (B) on the surface of the adhesive layer of the reinforcing film before use (before attachment to the substrate), thereby exhibiting light peelability (low adhesion) at the beginning of bonding. As monomer S1, a structure having a polymerizable reactive group at one end can be preferably used. According to a composition including such monomer S1 units and (meth)acrylic monomer units, a polymer (B) having a polyorganosiloxane backbone in the side chain is formed. Due to the mobility and ease of movement of the side chain, the polymer (B) with such a structure tends to have low initial adhesion and high adhesion after heating. In addition, in some embodiments, monomer S1 may preferably be adopted having a polymerizable reactive group at one end and not having a functional group at the other end that causes a cross-linking reaction with the polymer (A). A polymer (B) copolymerized with monomer S1 having such a structure is prone to having low initial adhesion and high adhesion after heating due to the mobility of the polyorganosiloxane structure derived from monomer S1.

[0105] As monomer S1, for example, a compound represented by the following general formula (1) or (2) may be used. More specifically, examples include X-22-174ASX, X-22-2426, X-22-2475, KF-2012, etc., which are single-terminal reactive silicone oils manufactured by Shin-Etsu Kagaku Kogyo Co., Ltd. Monomer S1 may be used alone or in combination of two or more types.

[0106]

[0107]

[0108] Here, R in the above general formulas (1) and (2) 3 is hydrogen or methyl, and R 4 is a methyl group or a monovalent organic group, and m and n are integers greater than or equal to 0.

[0109] The functional group equivalent of monomer S1 may be adopted as an appropriate value within the range where the desired effect is achieved using the monomer S1, and is not limited to a specific range. From the perspective of sufficiently suppressing initial adhesive strength, the functional group equivalent is, for example, 100 g / mol or more or 200 g / mol or more, and is suitable to be 300 g / mol or more (for example, 500 g / mol or more), preferably 800 g / mol or more, and more preferably 1500 g / mol or more. In a particularly preferred embodiment, from the perspective of achieving compatibility between low adhesive strength at the initial stage of application and increased adhesive strength after heating, the functional group equivalent is 2000 g / mol or more, and is also particularly preferably 2500 g / mol or more, and may be 3000 g / mol or more, 4000 g / mol or more, or 5000 g / mol or more. In some other embodiments, the functional group equivalent may be 9000 g / mol or more, 12000 g / mol or more, or 15000 g / mol or more. In the functional group equivalent of monomer S1, the functional group refers to a polymerizable functional group (e.g., an ethylenically unsaturated group such as a (meth)acryloyl group, a vinyl group, or an allyl group).

[0110] From the perspective of sufficiently increasing adhesive strength, the functional group equivalent is suitable to be, for example, 30,000 g / mol or less, 20,000 g / mol or less, less than 15,000 g / mol, or less than 10,000 g / mol. In some preferred embodiments, the functional group equivalent of monomer S1 is 7,000 g / mol or less, more preferably 5,500 g / mol or less, even more preferably 4,500 g / mol or less, 4,200 g / mol or less, or 3,500 g / mol or less. If the functional group equivalent of monomer S1 is within the above range, compatibility within the adhesive layer (e.g., compatibility with the base polymer) is easily improved, and the mobility of the polyorganosiloxane backbone (chain) of the polymer (B) is good, and the mobility of the polymer (B) is easy to control within an appropriate range, making it easy to realize an adhesive layer that achieves both low initial adhesion and increased adhesion after heating.

[0111] Here, "functional group equivalent" refers to the weight of the main backbone (e.g., polydimethylsiloxane) attached per functional group. Regarding the notation unit g / mol, it is converted to 1 mol of functional group. The functional group equivalent of monomer S1 is, for example, based on nuclear magnetic resonance (NMR). 1 It can be calculated from the spectral intensity of H-NMR (proton NMR). 1 The calculation of the functional group equivalent (g / mol) of monomer S1 based on the spectral intensity of H-NMR is, 1 Based on general structural analysis methods that affect H-NMR spectrum analysis, if necessary, this can be done by referring to the description in Japanese Patent Publication No. 5951153.

[0112] In addition, when using two or more types of monomers with different functional group equivalents as monomer S1, the arithmetic mean value may be used as the functional group equivalent of monomer S1. That is, n types of monomers with different functional group equivalents (monomer S11, monomer S12… monomer S1n The functional group equivalent of monomer S1 containing ) can be calculated by the following formula.

[0113] Functional group equivalent of monomer S1 (g / mol) = (Functional group equivalent of monomer S11 × Amount of monomer S11 + Functional group equivalent of monomer S12 × Amount of monomer S12 + … + monomer S1 n Functional group equivalent × Monomer S1 n (Amount of blending) / (Amount of blending monomer S11 + Amount of blending monomer S12 + … + monomer S1 n (amount of)

[0114] The content of monomer S1 may be adopted as an appropriate value within the range where the desired effect is achieved using the monomer S1, and is not limited to a specific range. In some embodiments, from the perspective of sufficiently suppressing initial tackiness, the content of monomer S1 in the total amount of monomer component (monomer raw material B) for preparing polymer (B) may be, for example, 5% by weight or more, and from the perspective of better exhibiting the effect as a tackiness increase retardant, it is preferable to be 10% by weight or more, more preferably 12% by weight or more, even more preferably 15% by weight or more, particularly preferably 18% by weight or more, and may be 20% by weight or more. In addition, the content of monomer S1 in monomer raw material B may be, for example, 80% by weight or less, and it is appropriate to be 60% by weight or less, preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 30% by weight or less, from the perspective of polymerization reactivity or compatibility. By setting the polymerization ratio of monomer S1 to an appropriate range, the increase in adhesive strength can be appropriately expressed.

[0115] Monomer raw material B includes a (meth)acrylic monomer capable of copolymerizing with monomer S1 in addition to monomer S1. By using one or more (meth)acrylic monomers, the mobility of the polymer (B) within the adhesive layer can be appropriately controlled. Furthermore, it can also help improve the compatibility between the polymer (B) and the polymer (A). Since the polymer (B) containing the (meth)acrylic monomer unit is compatible with the acrylic polymer, it is easy to achieve a reduction in initial adhesive strength and an improvement in adhesive strength after heating by improving the mobility of the polymer (B) within the adhesive layer.

[0116] In the polymer (B) used in the technology disclosed herein, the composition of the (meth)acrylic monomer included in the monomer raw material B is such that the glass transition temperature T of the polymer (B) B It can be appropriately set within a range of -20℃ to 5℃. The glass transition temperature T based on the composition of the (meth)acrylic monomer above B1 Also, the above T B It is appropriately set within a range that satisfies and is not limited to a specific range. Typically, T B1 Silver, glass transition temperature T of polymer (A) A It is desirable that it be set to be higher than T B1 It can be set to be higher than, for example, 0°C. Here, the glass transition temperature T based on the composition of the (meth)acrylic monomer is B1 Iran refers to Tg obtained by Fox's formula based on the composition of only (meth)acrylic monomers among the monomer components used in the preparation of polymer (B). B1Glass transition temperature T can be calculated by applying the aforementioned Fox formula to only the (meth)acrylic monomers among the monomer components used in the preparation of the polymer (B), based on the homopolymer glass transition temperature of each (meth)acrylic monomer and the weight fraction of each (meth)acrylic monomer in the total amount of the corresponding (meth)acrylic monomer. B1 According to this relatively high (typically higher than 0°C) polymer (B), the initial adhesive strength is easily suppressed. In addition, the glass transition temperature T B1 With this relatively high (typically higher than 0°C) polymer (B), it is easy to obtain a reinforcing film with a large increase in adhesive strength.

[0117] In some desirable embodiments, T B1 The temperature is 10°C or higher, more preferably 30°C or higher, even more preferably 40°C or higher, and may be 45°C or higher. B1 As this increases, the initial adhesive force tends to be better suppressed in general. This is, T B1 It is believed that, according to this polymer (B) at a temperature above a predetermined temperature, the improvement in the mobility or mobility of the polyorganosiloxane structural portion accompanying a temperature rise to room temperature or a certain high temperature range above room temperature is effectively suppressed by the monomer unit derived from the (meth)acrylic monomer included in the polymer (B), thereby allowing the low adhesion caused by the presence of the polyorganosiloxane structural portion to be maintained more effectively. In terms of maintaining the low adhesion at the initial stage of application more stably, in some embodiments, T B1 It may, for example, be 50℃ or higher, 55℃ or higher, or 60℃ or higher. Also, T B1 For example, it may be 120℃ or lower, or 100℃ or lower. B1 If this is lowered, the increase in adhesive strength by heating tends to be facilitated. In some preferred embodiments, T B1The temperature is, for example, 90°C or lower, more preferably 70°C or lower, even more preferably 60°C or lower, and particularly preferably 55°C or lower (for example, 50°C or lower).

[0118] T B1 In order to facilitate the effect of appropriately setting the amount, the total amount of monomer S1 and (meth)acrylic monomers in the total monomer component for preparing polymer (B) may be, for example, 50% by weight or more, 70% by weight or more, 85% by weight or more, 90% by weight or more, 95% by weight or more, and substantially 100% by weight.

[0119] Glass transition temperature T of the polymer (B) used in the technology disclosed herein B is within the range of -20℃ to 5℃. T of polymer (B) B Since the temperature is 5°C or lower, the mobility (typically thermogenic mobility) of the polymer (B) is improved, and the adhesive strength can be significantly increased. In some preferred embodiments, the T of the polymer (B) B It may be less than 0℃, -5℃ or lower, or -10℃ or lower. Also, T B Since the temperature is -20°C or higher, the polymer (B) located on the surface side of the adhesive layer contributes to the reduction of initial adhesive strength when attached to the substrate, and thus tends to have excellent peelability at the beginning of attachment. In some preferred embodiments, the T of the polymer (B) B It may be -15℃ or higher. T B By setting it to an appropriate range, the light peelability at the beginning of application and the increase in adhesive strength after heating can be controlled to a desirable range.

[0120] In some embodiments, the composition of the monomer component for preparing the polymer (B) is T B1 This T B To become higher, that is, T B1 -T BIt can be set so that it becomes greater than 0℃. According to such a composition, the effect of controlling the mobility of the polymer (B) by the composition of the (meth)acrylic monomer included in the monomer component is easily and suitably exerted. B1 -T B The temperature may, for example, be approximately 40°C to 100°C or approximately 50°C to 90°C. In some preferred embodiments, T B1 -T B The temperature is 45°C or higher, more preferably 50°C or higher, and even more preferably 55°C or higher (e.g., 58°C or higher). In addition, from the view of suitably expressing the effect of containing polymer (B), T B1 -T B The temperature is preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower (e.g., 62°C or lower).

[0121] In terms of making it easier to control the mobility of the polymer (B) within the adhesive layer, in some embodiments, the composition of the monomer component for preparing the polymer (B) is such that the glass transition temperature T of the polymer (A) A In relation to, T B Ga T A To become more than 20℃ higher, i.e., T B -T A It can be set so that it is 20℃ or higher. In some preferred embodiments, T B -T A is, for example, 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, and may be 60°C or higher, or 70°C or higher. In addition, from the perspective of increasing adhesive strength, T B -T A For example, it may be 130°C or lower, 120°C or lower, preferably 100°C or lower, more preferably 80°C or lower, even more preferably 65°C or lower, 55°C or lower, or 45°C or lower.

[0122] Examples of (meth)acrylic monomers that can be used as monomer raw material B include (meth)acrylate alkyl esters. The term "alkyl" as used herein refers to a chain-like (including straight and branched chain) alkyl group and does not include the alicyclic hydrocarbon groups described below. For example, one or more of the monomers exemplified above may be used as components of monomer raw material B as (meth)acrylate alkyl esters that can be used in polymer (A). In some preferred embodiments, monomer raw material B is (meth)acrylate C 4-12 Alkyl ester (preferably (meth)acrylic acid C) 4-10 Alkyl esters, e.g., (meth)acrylic acid C 6-10 It may contain at least one type of alkyl ester. In some other embodiments, monomer raw material B is methacrylic acid C 1-18 Alkyl ester (preferably C methacrylic acid) 1-14 Alkyl esters, e.g., methacrylic acid C 1-10 It may contain at least one type of alkyl ester. Monomer raw material B may include one or more types selected from, for example, MMA, n-butyl methacrylate (nBMA), and 2-ethylhexyl methacrylate (2EHMA) as (meth)acrylic monomers.

[0123] As another example of the above (meth)acrylic monomer, (meth)acrylic acid esters having a dicyclic hydrocarbon group may be cited. For example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclofentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, etc. may be used. In some embodiments, monomer raw material B may contain at least one selected from dicyclofentanyl methacrylate, isobornyl methacrylate, and cyclohexyl methacrylate as a (meth)acrylic monomer.

[0124] The content of the (meth)acrylate alkyl ester and the (meth)acrylate ester having an alicyclic hydrocarbon group in monomer raw material B may, for example, be 10% by weight or more and 95% by weight or less, 20% by weight or more and 95% by weight or less, 30% by weight or more and 90% by weight or less, 40% by weight or more and 90% by weight or less, or 50% by weight or more and 85% by weight or less. From the perspective of ease of increasing adhesive strength by heating, the use of (meth)acrylate alkyl ester may be advantageous. In some embodiments, the content of the (meth)acrylate ester having an alicyclic hydrocarbon group may be less than 50% by weight of monomer raw material B, less than 30% by weight, less than 15% by weight, less than 10% by weight, or less than 5% by weight. It is not necessary to use (meth)acrylic acid esters having a cycloaliphatic hydrocarbon group.

[0125] In some preferred embodiments, the (meth)acrylic monomer, which is a component of monomer raw material B, may include monomer M2, in which the Tg of the homopolymer is 50°C or higher. In the polymer (B), by copolymerizing monomer S1 and monomer M2, the mobility or mobility of the polyorganosiloxane structural portion accompanying the temperature rise is suitably controlled, making it easy to achieve both initial light peelability (reworkability) and increased adhesion after heating. In some embodiments, the Tg of the homopolymer of monomer M2 may be 60°C or higher, 70°C or higher, 80°C or higher, or 90°C or higher. Additionally, while the upper limit of the Tg of the homopolymer of monomer M2 is not particularly limited, it is generally suitable to be 200°C or lower from the perspective of ease of synthesis of the polymer (B). In some embodiments, the homopolymer Tg of monomer M2 may be, for example, 180°C or lower, 150°C or lower, or 120°C or lower.

[0126] As monomer M2, for example, among the (meth)acrylic monomers exemplified above, one that satisfies the condition of the homopolymer's Tg may be used. For example, one or more monomers selected from the group consisting of (meth)acrylic acid alkyl esters and (meth)acrylic acid esters having alicyclic hydrocarbon groups may be used. As for the (meth)acrylic acid alkyl ester, an alkyl methacrylic acid ester having 1 to 4 carbon atoms in the alkyl group may be preferably employed.

[0127] In an embodiment in which monomer raw material B includes monomer M2, the content of monomer M2 may, for example, be 5% by weight or more of monomer raw material B, 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, or 30% by weight or more. In some embodiments, the content of monomer M2 may be 35% by weight or more of monomer raw material B, 40% by weight or more, 45% by weight or more, 50% by weight or more, or 55% by weight or more. Additionally, the content of monomer M2 may, for example, be 90% by weight or less, typically 80% by weight or less, preferably 75% by weight or less, 70% by weight or less, or 65% by weight or less. In some preferred embodiments, the content of monomer M2 is 60% by weight or less (e.g., 50% by weight or less, typically 42% by weight or less). In the polymer (B), the copolymerization ratio of monomer M2 at Tg 50°C or higher is limited to a predetermined value or less, thereby allowing for an increase in adhesive strength after heating to be preferably realized based on the mobility of the polymer (B) at around 50°C. In the same view, the content of monomer M2 in the monomer raw material B may be 35% by weight or less, 25% by weight or less, or 15% by weight or less (e.g., 5% by weight or less).

[0128] The content of the monomer M2 may be preferably applied in an embodiment in which, for example, monomer M2 comprises one or more monomers selected from the group consisting of (meth)acrylate alkyl esters and (meth)acrylate esters having a cycloaliphatic hydrocarbon group, or in an embodiment in which monomer M2 comprises one or more monomers selected from (meth)acrylate alkyl esters (e.g., alkyl methacrylate esters). As a suitable example of such an embodiment, an embodiment in which the monomer M2 comprises MMA may be cited.

[0129] In some embodiments, the above (meth)acrylic monomer may include monomer M3, in which the Tg of the homopolymer is less than 50°C (typically between -20°C and 50°C). By using monomer M3, it becomes easier to obtain a reinforcing film that balances adhesive strength and cohesive strength well after the increase in adhesive strength. From the viewpoint of facilitating the exertion of this effect, it is preferable to use monomer M3 in combination with monomer M2.

[0130] As monomer M3, for example, one from among the (meth)acrylic monomers exemplified above that satisfies the condition of the homopolymer's Tg can be used. For example, one or more monomers selected from the group consisting of (meth)acrylate alkyl esters can be used.

[0131] In an embodiment in which monomer raw material B includes monomer M3, the content of monomer M3 may, for example, be 5% by weight or more of monomer raw material B, 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, or 35% by weight or more. In addition, the content of monomer M3 is typically suitable to be 70% by weight or less of monomer raw material B, and may be 60% by weight or less or 50% by weight or less. The above content of monomer M3 may be preferably applied in an embodiment in which monomer M3 consists of one or more monomers selected from (meth)acrylate alkyl esters (e.g., alkyl methacrylate esters).

[0132] In some embodiments of the reinforcing film disclosed herein, monomer raw material B preferably has a content of monomers with a homopolymer Tg higher than 170°C of 30% by weight or less. Here, the concept that the monomer content is X% by weight or less in this specification includes, unless otherwise specified, an embodiment in which the content of the monomer is 0% by weight, i.e., an embodiment that does not substantially contain the monomer. Furthermore, "substantially not containing" means that the monomer is not used, at least intentionally. If the copolymerization ratio of monomers with a homopolymer Tg higher than 170°C increases, the mobility of the polymer (B) tends to become insufficient, and it may be difficult to increase the adhesive strength by heating to a temperature range higher than 50°C.

[0133] In some embodiments, monomer raw material B is preferably a (meth)acrylic monomer containing at least MMA. According to the polymer (B) copolymerized with MMA, a reinforcing film with high adhesive strength after heating is easily obtained. The proportion of MMA in the total amount of (meth)acrylic monomers included in monomer raw material B may, for example, be 5 weight% or more, 10 weight% or more, 20 weight% or more, 30 weight% or more, or 40 weight% or more. In addition, the proportion of MMA in the total amount of monomer raw material B is typically suitable to be 95 weight% or less, and in some preferred embodiments, the proportion of MMA in the total amount of monomer raw material B may be 75 weight% or less, 65 weight% or less, 60 weight% or less, or 55 weight% or less (for example, 50 weight% or less) from the perspective of increasing adhesive strength after heating.

[0134] Other examples of monomers that may be included together with monomer S1 as monomer units constituting polymer (B) include monomers that can be used in polymer (A), such as the carboxyl group-containing monomer, acid anhydride group-containing monomer, hydroxyl group-containing monomer, epoxy group-containing monomer, cyano group-containing monomer, isocyanate group-containing monomer, amide group-containing monomer, monomer having a nitrogen atom-containing ring (N-vinyl cyclic amide, cyclic amide having a (meth)acryloyl group, monomer having a succinimide backbone, maleimides, itaconimides, etc.), (meth)acrylate aminoalkyls, vinyl esters, vinyl ethers, olefins, (meth)acrylic acid esters having aromatic hydrocarbon groups, (meth)acrylates containing heterocyclic rings, (meth)acrylates containing halogen atoms, and (meth)acrylic acid esters obtained from terpene compound derivative alcohols. there is.

[0135] As another example of a monomer that may be included together with monomer S1 as a monomer unit constituting the polymer (B), oxyalkylene di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate; a polymerizable polyoxyalkylene ether having a polymerizable functional group such as a (meth)acryloyl group, vinyl group, or allyl group at one end of a polyoxyalkylene chain, such as polyethylene glycol or polypropylene glycol, and an ether structure (alkyl ether, aryl ether, arylalkyl ether, etc.) at the other end, wherein the monomer has a polyoxyalkylene backbone; (Meth)acrylate alkoxyalkyls such as (meth)acrylate methoxyethyl, (meth)acrylate ethoxyethyl, (meth)acrylate propoxyethyl, (meth)acrylate butoxyethyl, (meth)acrylate ethoxypropyl; salts such as alkali metal salts of (meth)acrylate; polyvalent (meth)acrylates such as trimethylolpropane tri(meth)acrylate esters; vinyl halide compounds such as vinylidene chloride, (meth)acrylate-2-chloroethyl; oxazolin group-containing monomers such as 2-vinyl-2-oxazolin, 2-vinyl-5-methyl-2-oxazolin, 2-isopropenyl-2-oxazolin; aziridine group-containing monomers such as (meth)acryloylaziridine, (meth)acrylate-2-aziridinylethyl; Hydroxyl group-containing vinyl monomers such as (meth)acrylic acid-2-hydroxyethyl, (meth)acrylic acid-2-hydroxypropyl, lactones, and adducts of (meth)acrylic acid-2-hydroxyethyl; fluorine-containing vinyl monomers such as fluorine-substituted (meth)acrylic acid alkyl esters; reactive halogen-containing vinyl monomers such as 2-chloroethylvinyl ether and monochlorovinyl acetate; organosilicon-containing vinyl monomers such as vinyltrimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, allyltrimethoxysilane, trimethoxysilylpropylallylamine, and 2-methoxyethoxytrimethoxysilane;In addition, macromonomers having radical-polymerizable vinyl groups at the ends of monomers polymerized with vinyl groups may be examples. These can be copolymerized with monomer S1 either alone or in combination of two or more.

[0136] In some embodiments, the polymer (B) may preferably be adopted as one that does not have a functional group that causes a cross-linking reaction with the polymer (A). In other words, it is preferable that the polymer (B) be included in the adhesive layer in a form that is not chemically bonded to the polymer (A). An adhesive layer containing the polymer (B) in such a form has good mobility of the polymer (B) when heated, and is suitable for improving the ratio of adhesive strength increase. The functional group that causes a cross-linking reaction with the polymer (A) may vary depending on the type of functional group of the polymer (A), but may be, for example, an epoxy group, an isocyanate group, a carboxyl group, an alkoxysilyl group, an amino group, etc.

[0137] The Mw of the polymer (B) is not particularly limited. The Mw of the polymer (B) may be, for example, 1000 or more, or 5000 or more. In some preferred embodiments, the Mw of the polymer (B) is 10,000 or more, more preferably 12,000 or more, 15,000 or more, 20,000 or more, 22,000 or more, or 25,000 or more, in order to suitably express the increase in adhesive strength after heating. In some other embodiments, the Mw of the polymer (B) may be 30,000 or more, 50,000 or more, or 70,000 or more. The upper limit of the Mw of the polymer (B) is, for example, 500,000 or less, may be 350,000 or less, 200,000 or less, or 150,000 or less. In some preferred embodiments, the Mw of the polymer (B) is 100,000 or less, more preferably 80,000 or less, even more preferably 60,000 or less, particularly preferably 40,000 or less (e.g. 30,000 or less), may be 25,000 or less, and furthermore may be 20,000 or less, from the perspective of controlling compatibility or mobility within the adhesive layer to a suitable range to suitably express low tackiness at the initial stage of application. By setting the Mw of the polymer (B) to a suitable range, it is easy to obtain an adhesive that has excellent compatibility with light peelability and tackiness at the initial stage of application.

[0138] In some preferred embodiments, the Mw of polymer (B) is preferably lower than the Mw of polymer (A). This makes it easier to realize a reinforcing film that achieves both good reworkability at the initial stage of application and increased adhesive strength after heating. In some embodiments, the Mw of polymer (B) may be, for example, 0.8 times or less, 0.75 times or less, 0.5 times or less, or 0.3 times or less of the Mw of polymer (A). In some preferred embodiments, the Mw of polymer (A) AMw of polymer (B) for B The ratio of (Mw B / Mw A ) is 0.3 or less, more preferably 0.2 or less, even more preferably 0.1 or less, and particularly preferably 0.06 or less (e.g., 0.05 or less). In addition, the ratio (Mw B / Mw A ) is, for example, 0.010 or higher, preferably 0.020 or higher, more preferably 0.03 or higher, and even more preferably 0.04 or higher. By setting the Mw of polymer (A) and the Mw of polymer (B) to a suitable range, the effects of the technology disclosed herein can be better realized. In some other embodiments, the Mw of polymer (B) may be 0.03 times or less (e.g. 0.02 times or less) the Mw of polymer (A).

[0139] Polymer (B) can be produced by polymerizing, for example, the monomer described above by known methods such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization.

[0140] To adjust the molecular weight of the polymer (B), a chain transfer agent may be used as needed. Examples of chain transfer agents used include compounds having a mercapto group such as octyl mercaptan, lauryl mercaptan, t-nonyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, and α-thioglycerol; thioglycolic acid esters such as thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, thioglycolic acid ester of ethylene glycol, thioglycolic acid ester of neopentyl glycol, and thioglycolic acid ester of pentaerythritol; and α-methylstyrene dimer.

[0141] The amount of chain transfer agent used is not particularly limited, but typically, 0.05 to 20 parts by weight, preferably 0.1 to 15 parts by weight, and more preferably 0.2 to 10 parts by weight of the chain transfer agent are contained per 100 parts by weight of monomer. By adjusting the amount of chain transfer agent added in this way, a polymer (B) of suitable molecular weight can be obtained. The chain transfer agent may be used as a single type or in combination of two or more types.

[0142] As a means for adjusting the molecular weight of the polymer (B), various conventionally known means, including the use of the chain transfer agent, may be used alone or in appropriate combination. The same applies to the molecular weight of the polymer (A). Non-limiting examples of such means include the selection of a polymerization method, the selection of the type and amount of a polymerization initiator, the selection of a polymerization temperature, the selection of the type and amount of a polymerization solvent in a solution polymerization method, and the selection of the light irradiation intensity in a photopolymerization method. A person skilled in the art can understand how to obtain a polymer having a desired molecular weight based on the description of this specification, including the specific examples described below, and the technical common knowledge at the time of filing this application.

[0143] In the reinforcing film disclosed herein, the amount of polymer (B) used per 100 parts by weight of polymer (A) can be, for example, 0.1 parts by weight or more, and from the viewpoint of obtaining a higher effect (suitably, light peelability at the beginning of application), 0.5 parts by weight or more is preferred, 1 part by weight or more is more preferred, 1.5 parts by weight or more is even more preferred, and 2 parts by weight or more. In some embodiments, from the viewpoint of improving reworkability, the amount of polymer (B) used can be, for example, 3 parts by weight or more, 4 parts by weight or more, or 5 parts by weight or more. Furthermore, the amount of polymer (B) used per 100 parts by weight of polymer (A) can be, for example, 75 parts by weight or less, 30 parts by weight or less, 10 parts by weight or less, or 8 parts by weight or less. In terms of suitably realizing the desired increase in adhesive strength, in some preferred embodiments, the amount of polymer (B) used per 100 parts by weight of polymer (A) is 5 parts by weight or less, more preferably 4 parts by weight or less, even more preferably 3 parts by weight or less, and particularly preferably 2.5 parts by weight or less. In some other preferred embodiments, the amount of polymer (B) used per 100 parts by weight of polymer (A) is 1.5 parts by weight or less (e.g., 1.2 parts by weight or less). By keeping the amount of polymer (B) within the above range, it is easy to realize good bend recovery and bend retention. In addition, it is possible to better achieve a balance between light peelability at the initial stage of application and the increase in adhesive strength.

[0144] The adhesive layer may contain, as necessary, a polymer other than polymer (A) and polymer (B) (optional polymer) within a range that does not significantly impair the performance of the reinforcing film disclosed herein. The amount of such optional polymer used is typically 20% by weight or less of the total polymer component included in the adhesive layer, and may be 15% by weight or less, or 10% by weight or less. In some embodiments, the amount of the optional polymer used may be 5% by weight or less of the total polymer component, 3% by weight or less, or 1% by weight or less. The adhesive layer may also substantially not contain a polymer other than polymer (A) and polymer (B).

[0145] (Crosslinking agent)

[0146] In the adhesive layer, a crosslinking agent may be used as needed for purposes such as adjusting cohesive force. As a crosslinking agent, a crosslinking agent known in the field of adhesives may be used, and examples include epoxy-based crosslinking agents, isocyanate-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, and metal chelate-based crosslinking agents. Isocyanate-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-based crosslinking agents may be suitably used. As a crosslinking agent that suitably balances flex recovery and flex retention, an isocyanate-based crosslinking agent may be preferably used. The crosslinking agent may be used as a single type or in combination of two or more types.

[0147] As an isocyanate-based crosslinking agent, polyfunctional isocyanates (referring to compounds having an average of two or more isocyanate groups per molecule, including those having an isocyanurate structure) may be preferably used. Isocyanate-based crosslinking agents may be used alone or in combination of two or more types.

[0148] Examples of polyfunctional isocyanates include aliphatic polyisocyanates, cycloaliphatic polyisocyanates, and aromatic polyisocyanates.

[0149] Specific examples of aliphatic polyisocyanates include 1,2-ethylene diisocyanate; tetramethylene diisocyanates such as 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, and 1,4-tetramethylene diisocyanate; hexamethylene diisocyanates such as 1,2-hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 2,5-hexamethylene diisocyanate; and 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and lysine diisocyanate.

[0150] Specific examples of cycloaliphatic polyisocyanates include isophorone diisocyanate; cyclohexyl diisocyanates such as 1,2-cyclohexyl diisocyanate, 1,3-cyclohexyl diisocyanate, and 1,4-cyclohexyl diisocyanate; cyclopentyl diisocyanates such as 1,2-cyclopentyl diisocyanate and 1,3-cyclopentyl diisocyanate; hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0151] Specific examples of aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, and naphthylene-1,5-diisocyanate. Examples include 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, etc.

[0152] As a preferred polyfunctional isocyanate, a polyfunctional isocyanate having an average of three or more isocyanate groups per molecule is exemplified. Such trifunctional or higher isocyanates may be polymers of difunctional or trifunctional or higher isocyanates (e.g., dimers or tripmers), derivatives (e.g., addition reaction products of a polyhydric alcohol and two or more molecules of polyfunctional isocyanate), polymers, etc. Examples include dimers or trimers of diphenylmethane diisocyanate, isocyanurates of hexamethylene diisocyanate (trimeric adducts of an isocyanurate structure), reaction products of trimethylolpropane and tolylene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, trimethylolpropane adducts of xylylene diisocyanate, trimethylolpropane adducts of isophorone diisocyanate, trimethylolpropane adducts of hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate, polyester polyisocyanate, and adducts of these with various polyols, as well as polyisocyanates polyfunctionalized by isocyanurate bonds, biuret bonds, allophanate bonds, etc.

[0153] Examples of commercially available polyfunctional isocyanates include "Duranate TPA-100" manufactured by Asahi Kasei Chemicals, "Coronate L", "Coronate HL", "Coronate HK", "Coronate HX", "Coronate (2096)" manufactured by Tosho, and "Takenate D110N", "Takenate D120N", "Takenate D140N", and "Takenate D160N" manufactured by Mitsui Chemicals.

[0154] Examples of epoxy crosslinking agents include bisphenol A, epichlorohydrin-type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, diamine glycidylamine, N,N,N',N'-tetraglycidyl-m-xylylenediamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane. These may be used individually or in combination of two or more.

[0155] Examples of metal chelate compounds include aluminum, iron, tin, titanium, nickel, etc. as metal components, and acetylene, methyl acetoacetate, ethyl lactate, etc. as chelate components. These can be used individually or in combination of two or more types.

[0156] When using a crosslinking agent, the amount used is not particularly limited and, for example, can be an amount exceeding 0 parts by weight per 100 parts by weight of polymer (A). In addition, the amount of crosslinking agent used can be, for example, 0.01 parts by weight or more per 100 parts by weight of polymer (A), and it is preferable to use 0.05 parts by weight or more. As the amount of crosslinking agent used increases, the initial adhesive strength is suppressed, and reworkability tends to improve. Flexural recovery and processability tend to be excellent. In some embodiments, the amount of crosslinking agent used per 100 parts by weight of polymer (A) may be 0.1 parts by weight or more, 0.5 parts by weight or more, or 0.8 parts by weight or more. Meanwhile, in order to obtain an increase in adhesive strength after heating by appropriately allowing the mobility of the polymer (B), the amount of crosslinking agent used per 100 parts by weight of polymer (A) is typically 15 parts by weight or less, and may be 10 parts by weight or less, or 5 parts by weight or less.

[0157] The technology disclosed herein can preferably be implemented in an embodiment using at least an isocyanate-based crosslinking agent as the crosslinking agent. In some embodiments, with regard to achieving both good reworkability at the initial stage of application and increased adhesive strength after heating, the amount of isocyanate-based crosslinking agent used per 100 parts by weight of polymer (A) can be, for example, 0.01 parts by weight or more, preferably 0.05 parts by weight or more, more preferably 0.07 parts by weight or more, and may be 0.10 parts by weight or more, or 0.15 parts by weight or more (for example, 0.20 parts by weight or more). With an increase in the amount of isocyanate-based crosslinking agent, appropriate cohesive strength and elastic modulus are obtained, and there is a tendency for excellent flexural recovery and processability. In addition, the amount of isocyanate-based crosslinking agent used per 100 parts by weight of polymer (A) can be, for example, 5 parts by weight or less, preferably less than 1.0 part by weight, more preferably less than 0.5 parts by weight, even more preferably less than 0.3 parts by weight, and particularly preferably less than 0.2 parts by weight (for example, 0.15 parts by weight or less). By doing so, the cohesive force of the adhesive, and furthermore the elastic modulus (typically surface elastic modulus), is appropriately reduced, good flexural retention is obtained, and an increase in adhesive strength after heating is also easily obtained.

[0158] Although not specifically limited, when an isocyanate-based crosslinking agent is used in a composition in which the adhesive layer comprises a hydroxyl group-containing monomer as a monomer unit, the molar ratio of isocyanate groups and hydroxyl groups ([NCO] / [OH]) included in the adhesive layer can be, for example, 0.001 or higher. By increasing the amount of isocyanate-based crosslinking agent used relative to the hydroxyl group-containing monomer in this way, the elastic modulus of the adhesive (typically surface elastic modulus) is within a suitable range, and the flexural recovery tends to be improved. In addition, processability also tends to be excellent. In some preferred embodiments, the molar ratio ([NCO] / [OH]) is 0.002 or higher, more preferably 0.004 or higher, even more preferably 0.006 or higher (e.g., 0.007 or higher), and may be 0.010 or higher, 0.020 or higher, or 0.030 or higher. In addition, the above molar ratio ([NCO] / [OH]) may be, for example, 1.0 or less, or 0.10 or less. By limiting the above molar ratio to a predetermined value or less, a crosslinked structure suitable for significantly increasing the adhesive strength after heating relative to the adhesive strength at the initial application can be preferably formed. In some preferred embodiments, the above molar ratio ([NCO] / [OH]) is 0.030 or less, more preferably 0.015 or less, even more preferably 0.012 or less (e.g. 0.009 or less), and may be 0.005 or less. Furthermore, in the adhesive layer, the isocyanate group and the hydroxyl group may exist in a state where at least some of them are chemically bonded (crosslinked). More specifically, the above isocyanate group may exist in a state where it is chemically bonded (crosslinked) with the above hydroxyl group. Meanwhile, the above hydroxyl group may exist in a state where a part of it is chemically bonded to the isocyanate group, and another part is not chemically bonded (cross-linked) to the isocyanate group.

[0159] In some preferred embodiments, the adhesive layer comprises a catalyst. The catalyst may be added for the purpose of promoting the curing of the adhesive layer during the formation of the adhesive layer, typically for the purpose of more effectively carrying out any of the aforementioned crosslinking reactions. Accordingly, the catalyst is also referred to as a curing catalyst or a crosslinking catalyst. By adding the catalyst, initial curing is promoted, thereby suppressing side reactions that cause bubble formation on the surface of the adhesive layer. Examples of catalysts include organometallic compounds such as iron-based catalysts, tin-based catalysts, titanium-based catalysts, zirconium-based catalysts, lead-based catalysts, cobalt-based catalysts, and zinc-based catalysts, as well as tertiary amine compounds. These may be used individually or in combination of two or more. Among these, iron-based catalysts and tin-based catalysts are preferred due to the balance between reaction rate and pot life, and iron-based catalysts are particularly preferred.

[0160] Examples of iron-based catalysts include iron acetylacetonate and 2-iron ethylhexanate. Iron-based catalysts can be used individually or in combination of two or more types.

[0161] Examples of tin-based catalysts include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin maleate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, tributyltin methoxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, dioctyltin dilaurate, tributyltin chloride, tributyltin trichloroacetate, and 2-ethylhexanoate. Tin-based catalysts may be used individually or in combination of two or more types.

[0162] The amount of catalyst used is not particularly limited and can be, for example, 0.0001 parts by weight or more per 100 parts by weight of polymer (A), preferably 0.001 parts by weight or more, more preferably 0.003 parts by weight or more, even more preferably 0.006 parts by weight or more, and particularly preferably 0.008 parts by weight or more. By using an appropriate amount of catalyst, the generation of bubbles from the adhesive layer is suppressed, making it easier to obtain a smooth adhesive surface. In addition, the amount of catalyst used per 100 parts by weight of polymer (A) can be, for example, 1 part by weight or less, and may be 0.1 parts by weight or less. In some preferred embodiments, the amount of catalyst used per 100 parts by weight of polymer (A) is 0.03 parts by weight or less, more preferably 0.02 parts by weight or less, even more preferably 0.01 parts by weight or less, and may be 0.005 parts by weight or less. By appropriately limiting the content of the catalyst to 100 parts by weight of the polymer (A), it is easy to achieve a suitable increase in adhesive strength.

[0163] Although not specifically limited, when a catalyst is used in a composition in which the adhesive layer comprises a hydroxyl group-containing monomer as a monomer unit, the amount of catalyst used is such that the molar ratio of the catalyst to the hydroxyl group ([catalyst] / [OH]) included in the adhesive layer is, for example, 1.0 × 10⁻⁶ -6 It can be in an amount greater than or equal to, preferably 1.0 × 10⁻⁶ -5 Ideally, 1.0×10 -4 Ideally, 2.0×10 -4 Above, particularly preferably 3.0×10 -4 It is an amount that is greater than or equal to 10. By using an appropriate amount of catalyst, the generation of bubbles from the adhesive layer is suppressed, making it easier to obtain a smooth adhesive surface. In addition, the above molar ratio ([catalyst] / [OH]) is, for example, 5.0 × 10 -2 It can be less than or equal to 5.0×10 -3 It may be less than or equal to this. In some preferred embodiments, the molar ratio ([catalyst] / [OH]) is 3.0 × 10⁻⁶ -3Less than or equal to, and more preferably 1.0×10 -3 Below, more preferably 5.0×10 -4 Less than or equal to, 3.0×10 -4 The following may be acceptable. By appropriately limiting the catalyst content, it is easy to achieve a suitable increase in adhesive strength.

[0164] (Adhesion-enhancing resin)

[0165] The adhesive layer may include a tackifying resin as needed. The tackifying resin is not particularly limited, but examples include rosin-based tackifying resin, terpene-based tackifying resin, phenol-based tackifying resin, hydrocarbon-based tackifying resin, ketone-based tackifying resin, polyamide-based tackifying resin, epoxy-based tackifying resin, elastomer-based tackifying resin, etc. The tackifying resin may be used as a single type or in combination of two or more types.

[0166] The content of the tackifying resin is not particularly limited and can be set to ensure appropriate adhesive performance depending on the purpose or application. The content of the tackifying resin (or the total amount thereof in cases where two or more types of tackifying resins are included) per 100 parts by weight of polymer (A) can be, for example, about 5 to 500 parts by weight. Furthermore, the technology disclosed herein can preferably be implemented in an embodiment in which the amount of tackifying resin used is limited. For example, the content of the tackifying resin per 100 parts by weight of polymer (A) can be less than 20 parts by weight, less than 10 parts by weight, less than 3 parts by weight, or less than 1 part by weight (0 to less than 1 part by weight), and in some embodiments, the adhesive layer does not substantially contain the tackifying resin.

[0167] In addition, the adhesive layer in the technology disclosed herein may, as necessary, include known additives that can be used in adhesives, such as leveling agents, plasticizers, softeners, coloring agents (dyes, pigments, etc.), fillers, antistatic agents, anti-aging agents, ultraviolet absorbers, antioxidants, light stabilizers, and preservatives, to the extent that the effects of the present invention are not significantly hindered.

[0168] The adhesive layer constituting the reinforcing film disclosed herein may be a cured layer of an adhesive composition. That is, the adhesive layer may be formed by applying (e.g., coating) an adhesive composition such as a water-dispersible, solvent-based, photocurable, or hot-melt type to a suitable surface and then appropriately performing a curing treatment. When two or more types of curing treatments (drying, crosslinking, polymerization, cooling, etc.) are performed, these may be performed simultaneously or in multiple stages. In an adhesive composition using a partial polymer of monomer raw materials (polymer syrup), typically, a final copolymerization reaction is performed as the above curing treatment. That is, the partial polymer is subjected to a further copolymerization reaction to form a complete polymer. For example, in the case of a photocurable adhesive composition, light irradiation is performed. If necessary, curing treatments such as crosslinking or drying may be performed. For example, if drying is required for a photocurable adhesive composition, photocuring may be performed after drying. In an adhesive composition using a fully polymerized material, typically, as a curing treatment, treatments such as drying (heat drying) and crosslinking are performed as necessary.

[0169] The application of the adhesive composition can be carried out using a conventional coater, such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater.

[0170] The thickness of the adhesive layer is not particularly limited and can be, for example, 6 μm or more. In some embodiments, the thickness of the adhesive layer may be 8 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, or exceed 20 μm. As the thickness of the adhesive layer increases, the adhesive strength after heating tends to increase. In addition, in some embodiments, the thickness of the adhesive layer may be, for example, 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, or 40 μm or less. Not having too large a thickness of the adhesive layer can be advantageous from the perspective of thinning the reinforcing film or preventing cohesive failure of the adhesive layer. A reinforcing film having an adhesive layer with a thickness within the aforementioned range may have a balanced adhesive properties such as adhesive strength, flex recovery, and flex retention. In addition, in the case of a reinforcing film having a first adhesive layer and a second adhesive layer on a first surface and a second surface of a substrate, the thickness of the aforementioned adhesive layer may be applied to at least the thickness of the first adhesive layer. The thickness of the second adhesive layer may also be selected within the same range. Furthermore, in the case of a reinforcing film without a substrate, the thickness of the reinforcing film matches the thickness of the adhesive layer.

[0171] <Support Information>

[0172] A reinforcing film according to some embodiments may be in the form of a substrate-equipped adhesive sheet having an adhesive layer on one or both sides of a supporting substrate. The material of the supporting substrate is not particularly limited and can be appropriately selected depending on the purpose or mode of use of the reinforcing film. Non-limiting examples of substrates that can be used include resin films such as plastic films; foam sheets including foams such as polyurethane foam, polyethylene foam, and polychloroprene foam; woven and nonwoven fabrics made of various fibrous materials (which may be natural fibers such as linen and cotton, synthetic fibers such as polyester and vinylon, and semi-synthetic fibers such as acetate), either alone or in a blend; papers such as Japanese paper, high-quality paper, kraft paper, and crepe paper; and metal foils such as aluminum foil and copper foil. A substrate with a composite composition of these may also be used. Examples of such composite substrates include, for instance, a substrate with a structure in which a metal foil and the above-mentioned plastic film are laminated, and a plastic substrate reinforced with inorganic fibers such as glass cloth.

[0173] Various film substrates may preferably be used as the substrate for the reinforcing film disclosed herein. The film substrate may be a porous substrate, such as a foam film or a non-woven sheet, a non-porous substrate, or a substrate having a structure in which a porous layer and a non-porous layer are laminated. In some embodiments, the film substrate may preferably include a resin film capable of maintaining its shape independently (self-supporting or non-dependent) as a base film. Here, "resin film" refers to a resin film having a non-porous structure and, typically, substantially not containing bubbles (voidless). Therefore, the resin film is a concept distinct from foam films or non-woven fabrics. The resin film may preferably be capable of maintaining its shape independently (self-supporting or non-dependent). The resin film may have a single-layer structure or a multi-layer structure of two or more layers (e.g., a three-layer structure).

[0174] As a resin material constituting the resin film, for example, polyamide (PA) such as polyester, polyolefin, nylon 6, nylon 66, and partially aromatic polyamide, polyimide (PI), polyamideimide (PAI), polyetheretherketone (PEEK), polyethersulfone (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), fluoropolymer such as ethylene-vinyl acetate copolymer (EVA) and polytetrafluoroethylene (PTFE), acrylic resin, polyacrylate, polystyrene, polyvinyl chloride, polyvinylidene chloride, etc., may be used. The resin film may be formed using a resin material containing only one of these resins, or it may be formed using a resin material in which two or more types are blended. The resin film may be unstretched, or it may be stretched (for example, uniaxial or biaxial stretching).

[0175] Suitable examples of resin materials constituting a resin film include polyimide resins, polyester resins, PPS resins, and polyolefin resins. Here, polyimide resin refers to a resin containing polyimide in a ratio exceeding 50% by weight. Likewise, polyester resin refers to a resin containing polyester in a ratio exceeding 50% by weight, PPS resin refers to a resin containing PPS in a ratio exceeding 50% by weight, and polyolefin resin refers to a resin containing polyolefin in a ratio exceeding 50% by weight.

[0176] Specific examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate.

[0177] As for the polyolefin resin, one type of polyolefin may be used alone, or two or more types of polyolefins may be used in combination. The polyolefin may be, for example, a homopolymer of α-olefin, a copolymer of two or more types of α-olefin, or a copolymer of one or two or more types of α-olefin and another vinyl monomer. Specific examples include polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene rubber (EPR), ethylene-propylene-butene copolymer, ethylene-butene copolymer, ethylene-vinyl alcohol copolymer, ethylene-ethyl acrylate copolymer, etc. Both low-density (LD) polyolefins and high-density (HD) polyolefins may be used. Examples of polyolefin resin films include non-oriented polypropylene (CPP) films, biaxially oriented polypropylene (OPP) films, low-density polyethylene (LDPE) films, linear low-density polyethylene (LLDPE) films, medium-density polyethylene (MDPE) films, high-density polyethylene (HDPE) films, polyethylene (PE) films blended from two or more types of polyethylene (PE), and PP / PE blend films blended from polypropylene (PP) and polyethylene (PE).

[0178] Specific examples of resin films that can be preferably used as base films for reinforcing films disclosed herein include PI film, PET film, PEN film, PPS film, PEEK film, CPP film, and OPP film.

[0179] In the resin film, known additives such as light stabilizers, antioxidants, antistatic agents, coloring agents (dyes, pigments, etc.), fillers, slip agents, and anti-blocking agents may be incorporated as needed, within a range where the effects of the present invention are not significantly impaired. The amount of additives incorporated is not particularly limited and can be appropriately set according to the purpose, etc.

[0180] The method of manufacturing the resin film is not particularly limited. For example, conventionally known general resin film molding methods such as extrusion molding, inflation molding, T-die casting, and calender roll molding can be appropriately employed.

[0181] The above-mentioned material may be substantially composed of such a base film. Alternatively, the above-mentioned material may include an auxiliary layer in addition to the base film. Examples of the above-mentioned auxiliary layer include an optical property adjusting layer (e.g., a coloring layer, an anti-reflective layer), a printing layer or a laminate layer for imparting a desired appearance to the material, an antistatic layer, a primer layer, a release layer, and other surface treatment layers.

[0182] The thickness of the substrate is not specifically limited and can be selected according to the purpose or mode of use of the reinforcing film. For example, the thickness of the substrate may be 1000 μm or less. In some embodiments, from the perspective of handling or processability of the reinforcing film, the thickness of the substrate may be, for example, 500 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less. From the perspective of miniaturization or weight reduction of the product to which the reinforcing film is applied, in some embodiments, the thickness of the substrate may be, for example, 160 μm or less, 130 μm or less, 100 μm or less, 90 μm or less, 80 μm or less, 60 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, or 5 μm or less. As the thickness of the substrate decreases, the flexibility of the reinforcing film or its ability to follow the surface shape of the substrate tends to improve. Additionally, from the perspective of handling and processability, the thickness of the substrate may be, for example, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 25 μm or more, or exceed 25 μm. In some embodiments, the thickness of the substrate may be, for example, 30 μm or more, 35 μm or more, 55 μm or more, 70 μm or more, 75 μm or more, 90 μm or more, or 120 μm or more. For example, in the reinforcing film, a substrate with a thickness of 30 μm or more may be preferably adopted.

[0183] On the first surface of the substrate, conventionally known surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and the formation of an undercoat layer by applying a primer may be performed as needed. Such surface treatments may be treatments intended to improve the anchoring properties of the adhesive layer on the substrate. For example, in a reinforcing film having a substrate comprising a resin film as a base film, a substrate having undergone such anchoring properties improvement treatment may be preferably adopted. The above surface treatments may be applied alone or in combination. The composition of the primer used for forming the undercoat layer is not particularly limited and can be appropriately selected from known ones. The thickness of the undercoat layer is not particularly limited, but typically, about 0.01 μm to 1 μm is suitable, and about 0.1 μm to 1 μm is preferred. Other treatments that may be performed on the first surface of the substrate as needed include antistatic layer formation treatment, coloring layer formation treatment, printing treatment, etc.

[0184] In the case where the reinforcing film disclosed herein is in the form of a single-sided adhesive sheet having an adhesive layer only on the first side of the substrate, conventional surface treatments such as a release treatment or an antistatic treatment may be performed on the second side of the substrate as needed. For example, by surface treating the back side of the substrate with a release agent (typically by forming a release layer with the release agent), the rewinding force of the reinforcing film wound in a roll shape can be reduced. As the release agent, silicone-based release agents, long-chain alkyl-based release agents, olefin-based release agents, fluorine-based release agents, fatty acid amide-based release agents, molybdenum sulfide, silica powder, etc. may be used. In addition, treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, and alkali treatment may be performed on the second side of the substrate for purposes such as improving printability, reducing light reflectivity, and improving overlapability. In addition, in the case of a double-sided adhesive sheet, the second side of the substrate may be subjected to a surface treatment similar to that exemplified above, which can be applied to the first side of the substrate as needed. In addition, the surface treatment applied to the first side of the substrate and the surface treatment applied to the second side may be the same or different.

[0185] Characteristics of Reinforcement Films

[0186] The reinforcing film disclosed herein has an initial adhesion strength N measured after being bonded to a stainless steel plate and maintained at 23°C for 30 minutes. 23 It is desirable that this be limited to a predetermined value or less. In some embodiments, adhesive strength N 23 It is preferably, for example, less than 500gf / 25mm, more preferably less than 400gf / 25mm, even more preferably less than 300gf / 25mm, particularly preferably 250gf / 25mm or less (e.g. 200gf / 25mm or less), and may be 150gf / 25mm or less. Adhesion N 23This low value is desirable from the perspective of reworkability. Adhesion N 23 The lower limit of is not specifically restricted and may, for example, be 1 gf / 25 mm or more. From the perspective of workability for application to the substrate or prevention of positional misalignment before the adhesive strength increases, the adhesive strength N 23 It is generally suitable for the value to be 10 gf / 25 mm or higher. In terms of improving adhesive strength after heating, etc., in some embodiments, adhesive strength N 23 It may be, for example, 20gf / 25mm or more, 50gf / 25mm or more, 80gf / 25mm or more, or 100gf / 25mm or more (for example, 150gf / 25mm or more).

[0187] Adhesion N 23 [gf / 25 mm] is determined by pressing the material onto a stainless steel (SUS) plate as the substrate, leaving it for 30 minutes in an environment of 23°C and 50%RH, and then measuring the 180° peel adhesion strength under the same conditions (i.e., at 23°C), with a peel angle of 180° and a tensile speed of 300 mm / min. A SUS304BA plate is used as the substrate. For the measurement, if necessary, the reinforcing film of the measurement target may be reinforced by attaching a suitable backing material (e.g., a PET film with a thickness of approximately 25 μm). Adhesion strength N 23 More specifically, it can be measured in accordance with the method for measuring initial adhesive strength described in the embodiments below.

[0188] The reinforcing film disclosed herein has an adhesive strength that increases upon heating, and, for example, has an adhesive strength N of 300gf / 25mm or more. 60 , that is, it may represent the adhesive strength measured at 23°C after being bonded to a stainless steel plate and maintained at 60°C for 60 minutes. In some embodiments, the adhesive strength N 60It is 400gf / 25mm or more, and 500gf / 25mm or more is suitable. A reinforcing film satisfying these characteristics has its adhesive strength rise to a predetermined value or higher upon heating after being attached to a substrate. According to the technology disclosed herein, it is possible to obtain strong adhesive strength through heating. In some preferred embodiments, the adhesive strength N 60 The tackiness is 600gf / 25mm or more, more preferably 700gf / 25mm or more, and may be 800gf / 25mm or more, or 900gf / 25mm or more. Adhesion N 60 The upper limit of is not specifically restricted. From the perspective of ease of manufacture or economic feasibility of the reinforcing film, in some embodiments, the adhesive strength N 60 For example, it may be 3000gf / 25mm or less, 1500gf / 25mm or less, or 1000gf / 25mm or less.

[0189] Adhesion N 60 [gf / 25 mm] is determined by pressing a SUS plate as the substrate, maintaining it in a 60° environment for 60 minutes, and then leaving it in a 23°, 50% RH environment for 30 minutes, followed by measuring the 180° peel adhesion strength under conditions of a peel angle of 180 degrees and a tensile speed of 300 mm / min in the same environment. As for the substrate, the adhesion strength N 23 Similarly, a SUS304BA plate is used. For measurement, if necessary, the reinforcing film of the measurement target can be reinforced by attaching a suitable backing material (e.g., a PET film with a thickness of about 25 μm). Adhesion strength N 60 More specifically, it can be measured in accordance with the method for measuring adhesive strength after heating described in the embodiments below.

[0190] Adhesion N 23 Adhesion N for [gf / 25㎜] 60 The ratio of [gf / 25㎜], i.e., the ratio of the increase in adhesive strength N 60 / N 23 ...is not specifically limited, but in some modes, N 60 / N 23 It is suitable for N to be 1.5 or higher, preferably 2.0 or higher, more preferably 2.5 or higher, even more preferably 3.0 or higher (e.g., 3.5 or higher), and may be greater than 5.0 (e.g., greater than 7.0). 60 / N 23 According to this large reinforcing film, good reworkability is exhibited during the initial application, and the adhesive strength can be significantly increased thereafter through heating, etc. N 60 / N 23 The upper limit of is not specifically limited and is typically 100 or less; however, from the perspective of ease of manufacturing or economic feasibility of the reinforcing film, it may be 30 or less, 15 or less, or 10 or less. In some embodiments, N 60 / N 23 For example, it may be 5 or less, 3 or less, or 2 or less.

[0191] Furthermore, the adhesive strength of the reinforcing film disclosed herein after heating represents one characteristic of the reinforcing film and does not limit the mode of use of the reinforcing film. In other words, the mode of use of the reinforcing film disclosed herein is not limited to a mode of heating at 60°C for 60 minutes, and can also be used in a mode in which a treatment of heating above, for example, room temperature (typically 20°C to 30°C, usually 23°C to 25°C) is not specifically performed. Even in such a mode of use, the adhesive strength increases over the long term, and a strong bond can be realized. In addition, the reinforcing film disclosed herein can promote an increase in adhesive strength by performing a heat treatment at a temperature above 30°C (e.g., 50 to 70°C) or higher than 60°C at any timing after application. The heating temperature in this heat treatment is not specifically limited and can be set considering workability, economic efficiency, and the heat resistance of the substrate of the reinforcing film or the substrate. The heating temperature may, for example, be less than 150°C, 120°C or less, 100°C or less, 80°C or less, or 70°C or less. In addition, the heating temperature may, for example, be 40°C or higher, 45°C or higher, 50°C or higher, 55°C or higher, 60°C or higher, or 70°C or higher, or 80°C or higher, or 100°C or higher. The heating time is not specifically limited and may, for example, be 3 hours or less, 1 hour or less, 30 minutes or less, or 10 minutes or less. In addition, the heating time may, for example, be 1 minute or more, 15 minutes or more, 30 minutes or more, or 1 hour or more. Alternatively, a longer heat treatment may be performed to the extent that significant thermal degradation does not occur in the reinforcing film or the substrate. Furthermore, the heat treatment may be performed in a single step or divided into multiple steps.

[0192] <Reinforcement film for substrates>

[0193] When the reinforcing film disclosed herein is in the form of an adhesive sheet having a substrate, the thickness of the reinforcing film may be, for example, 1000 μm or less, 600 μm or less, 350 μm or less, or 250 μm or less. In some embodiments, from the perspective of miniaturization, lightweighting, thinning, etc. of the product to which the reinforcing film is applied, the thickness of the reinforcing film may be, for example, 200 μm or less, 175 μm or less, 140 μm or less, 120 μm or less, or 100 μm or less (for example, less than 100 μm). In addition, from the perspective of handling, etc., the thickness of the reinforcing film may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, or 30 μm or more. In some embodiments, the thickness of the reinforcing film may be, for example, 50 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, or 120 μm or more. The upper limit of the thickness of the reinforcing film is not particularly limited.

[0194] In addition, the thickness of the reinforcing film refers to the thickness of the portion attached to the substrate. For example, in the reinforcing film (1) of the configuration shown in FIG. 1, it refers to the thickness from the adhesive surface (21A) of the reinforcing film (1) to the second surface (10B) of the substrate (10), and does not include the thickness of the release liner (31).

[0195] The reinforcing film disclosed herein may be suitably implemented, for example, in an embodiment where the thickness Ts of the supporting substrate is greater than the thickness Ta of the adhesive layer, that is, in an embodiment where Ts / Ta is greater than 1. Although not particularly limited, Ts / Ta may, for example, be 1.1 or greater, 1.2 or greater, 1.5 or greater, or 1.7 or greater. For example, as Ts / Ta increases, there is a tendency for good effects to be easily exhibited even when the reinforcing film is made thin. In some embodiments, Ts / Ta may be 2 or greater (for example, greater than 2), 2.5 or greater, or 2.8 or greater. Additionally, Ts / Ta may, for example, be 50 or less, or 20 or less. From the perspective of making it easier to exhibit adhesive strength after high heating even when the reinforcing film is made thin, Ts / Ta may, for example, be 10 or less, 8 or less, or 5 or less.

[0196] It is preferable that the adhesive layer is fixed to the support substrate. Here, "fixation" refers to a reinforcing film in which the adhesive strength increases after attachment to a substrate, such that the adhesive layer exhibits sufficient anchoring ability to the support substrate to the extent that delamination does not occur at the interface between the adhesive layer and the support substrate when the reinforcing film is peeled from the substrate. According to a reinforcing film equipped with a substrate in which the adhesive layer is fixed to the support substrate, the substrate and the support substrate can be firmly integrated. As a suitable example of a reinforcing film in which the adhesive layer is fixed to the substrate, a reinforcing film in which delamination (anchoring failure) does not occur between the adhesive layer and the support substrate when measuring the adhesive strength after heating as described above may be cited. A reinforcing film in which anchoring failure does not occur when measuring the adhesive strength after heating is a suitable example corresponding to a reinforcing film in which the adhesive layer is fixed to the substrate.

[0197] The reinforcing film disclosed herein can be preferably manufactured by a method comprising, for example, contacting a liquid adhesive composition with a first surface of a substrate and curing the adhesive composition on the first surface to form an adhesive layer. The curing of the adhesive composition may involve one or more of drying, crosslinking, polymerization, and cooling of the adhesive composition. According to the method of forming an adhesive layer by curing a liquid adhesive composition on the first surface of a substrate in this manner, the anchoring ability of the adhesive layer to the substrate can be increased compared to the method of placing the adhesive layer on the first surface by bonding the adhesive layer after curing to the first surface of the substrate. By utilizing this, a reinforcing film in which the adhesive layer is fixed to the substrate can be suitably manufactured.

[0198] In some embodiments, as a method for contacting a liquid adhesive composition to a first surface of a substrate, a method of directly applying the adhesive composition to the first surface of the substrate may be adopted. By bringing the first surface (adhesive surface) of the adhesive layer cured on the first surface of the substrate into contact with the release surface, a reinforcing film can be obtained in which the second surface of the adhesive layer is fixed to the first surface of the substrate and the first surface of the adhesive layer is in contact with the release surface. As the release surface, the surface of a release liner or the back surface of a substrate that has undergone a release treatment may be used.

[0199] In addition, for example, in the case of a photocurable adhesive composition using a partial polymer of monomer raw materials (polymer syrup), for example, the adhesive composition may be applied to a release surface, and then the first surface of the substrate may be covered with the applied adhesive composition to bring the first surface of the substrate into contact with the uncured adhesive composition, and then, in that state, the adhesive composition sandwiched between the first surface of the substrate and the release surface may be irradiated with light to cure it, thereby forming an adhesive layer.

[0200] Furthermore, the method exemplified above does not limit the method for manufacturing the reinforcing film disclosed herein. When manufacturing the reinforcing film disclosed herein, one or more appropriate methods capable of fixing an adhesive layer to the first surface of a substrate may be used in combination. Examples of such methods include a method of forming an adhesive layer by curing a liquid adhesive composition on the first surface of a substrate as described above, or a method of performing a surface treatment to improve the anchoring properties of the adhesive layer on the first surface of a substrate. For example, if the anchoring properties of the adhesive layer to the substrate can be sufficiently improved by methods such as providing a primer layer on the first surface of a substrate, the reinforcing film may be manufactured by bonding the adhesive layer after curing to the first surface of the substrate. In addition, the anchoring properties of the adhesive layer to the substrate can also be improved by selecting the material of the substrate or the composition of the adhesive. In addition, by applying a temperature higher than room temperature to a reinforcing film having an adhesive layer on a first surface of a substrate, the anchoring ability of the adhesive layer to the substrate can be increased. The temperature applied to increase anchoring ability may be, for example, about 35°C to 80°C, about 40°C to 70°C or higher, or about 45°C to 60°C.

[0201] When the reinforcing film disclosed herein is in the form of an adhesive sheet (i.e., an adhesive sheet having a double-sided adhesive substrate) having a first adhesive layer provided on a first surface of a substrate and a second adhesive layer provided on a second surface of the substrate, the first adhesive layer and the second adhesive layer may have the same composition or different compositions. If the compositions of the first adhesive layer and the second adhesive layer are different, the difference may be, for example, a difference in composition or a difference in structure (thickness, surface roughness, formation range, formation pattern, etc.). For example, the second adhesive layer may be an adhesive layer that does not contain a polymer (B). In addition, the surface of the second adhesive layer (second adhesive surface) may have a surface elastic modulus at 23°C outside the range of 1 to 20 kPa (for example, greater than 20 kPa) or 30 kPa or more.

[0202] Reinforcement film equipped with a release liner

[0203] The reinforcing film disclosed herein may take the form of an adhesive product in which the surface (adhesive surface) of an adhesive layer is in contact with the release surface of a release liner. Accordingly, by this specification, a reinforcing film equipped with a release liner may be provided, comprising any reinforcing film disclosed herein and a release liner having a release surface in contact with the adhesive surface of said reinforcing film.

[0204] The thickness of the release liner is not particularly limited, but is typically about 5 μm to 200 μm. It is desirable for the thickness of the release liner to be within the above range because it provides excellent bonding workability to the adhesive layer and excellent peeling workability from the adhesive layer. In some embodiments, the thickness of the release liner may be, for example, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. Additionally, from the perspective of facilitating peeling from the adhesive layer, the thickness of the release liner may be, for example, 100 μm or less, or 80 μm or less. If necessary, a known antistatic treatment, such as a coating type, a paste type, or a deposition type, may be applied to the release liner.

[0205] As for the release liner, it is not particularly limited, and for example, a release liner having a release layer on the surface of a liner substrate such as a resin film or paper (which may be paper laminated with a resin such as polyethylene), or a release liner comprising a resin film formed from a low-adhesion material such as a fluorine-based polymer (polytetrafluoroethylene, etc.) or a polyolefin-based resin (polyethylene, polypropylene, etc.) may be used. In terms of excellent surface smoothness, a release liner having a release layer on the surface of a resin film as a liner substrate, or a release liner comprising a resin film formed from a low-adhesion material, may be preferably adopted. As for the resin film, it is not particularly limited as long as it is a film capable of protecting the adhesive layer, and examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyester film (PET film, PBT film, etc.), polyurethane film, ethylene-vinyl acetate copolymer film, etc. For forming the above-mentioned peeling layer, known peeling agents such as silicone-based peeling agents, long-chain alkyl-based peeling agents, olefin-based peeling agents, fluorine-based peeling agents, fatty acid amide-based peeling agents, molybdenum sulfide, silica powder, etc., may be used. The use of silicone-based peeling agents is particularly preferred.

[0206] The thickness of the release layer is not particularly limited, but typically 0.01 μm to 1 μm is suitable, and 0.1 μm to 1 μm is preferable. The method of forming the release layer is not particularly limited, and known methods depending on the type of release agent used can be appropriately adopted.

[0207] <Uses>

[0208] The reinforcing film provided by this specification is capable of exhibiting good reworkability, for example, in the initial stage after being bonded to a substrate, and thus can contribute to suppressing yield reduction or improving the quality of products containing said reinforcing film. Furthermore, the reinforcing film can significantly increase its adhesive strength by aging or heating after being attached to a substrate. For example, by heating at an appropriate timing after being attached to a substrate, the reinforcing film can be firmly bonded to the substrate. Taking advantage of these characteristics, the reinforcing film disclosed herein can be preferably used for reinforcing components included in various products in various fields.

[0209] The reinforcing film disclosed herein may preferably be used as a reinforcing film that reinforces a substrate by being attached to the substrate, for example, in the form of an adhesive sheet having a film-shaped substrate having a first surface and a second surface, wherein an adhesive layer is formed on at least one surface of the film-shaped substrate. In such a reinforcing film, the film substrate may preferably include a resin film as a base film. Furthermore, from the viewpoint of enhancing reinforcing performance, it is preferable that the adhesive layer be fixed to the first surface of the film-shaped substrate.

[0210] For example, in optical components used in optical products or electronic components used in electronic products, high levels of integration, miniaturization, and thinning are being pursued, and multiple thin optical / electronic components with different coefficients of linear expansion or thicknesses may be laminated. By attaching a reinforcing film as described above to these components, appropriate rigidity can be imparted to the optical / electronic components. Accordingly, curling or bending caused by stress that may occur between multiple components with different coefficients of linear expansion or thicknesses during the manufacturing process and / or in the product after manufacturing can be suppressed.

[0211] In addition, in the manufacturing process of optical products / electronic products, when shape processing such as cutting is performed on thin optical / electronic components as described above, by attaching a reinforcing film to the component, localized stress concentration on the optical / electronic component accompanying the processing can be alleviated, and risks such as cracks, fissures, and delamination of laminated components can be reduced. Handling optical / electronic components with a reinforcing film attached can also help alleviate localized stress concentration during conveying, lamination, or rotation of the component, and suppress bending or curvature caused by the component's own weight.

[0212] Furthermore, when a device such as an optical product or electronic product containing the above-mentioned reinforcing film is used by a consumer in the market, the inclusion of the reinforcing film can alleviate the stress applied to the device even when unintentional stress is applied, such as when the device is dropped, placed under a heavy object, or collides with a flying object. Therefore, the inclusion of the reinforcing film in the device can improve the durability of the device.

[0213] In addition, the reinforcing film disclosed herein may preferably be used in a manner such as being attached to a component constituting various portable devices. Here, "portable" is not merely sufficient if it is possible to carry, but is understood to mean having a level of portability that allows an individual (a standard adult) to carry it relatively easily. Furthermore, examples of portable devices referred to herein may include, in addition to portable electronic devices such as mobile phones, smartphones, tablet-type personal computers, laptop computers, various wearable devices, digital cameras, digital video cameras, audio devices (portable music players, IC recorders, etc.), calculators (electronic desktop calculators, etc.), portable game devices, electronic dictionaries, electronic notebooks, electronic books, vehicle-mounted information devices, portable radios, portable TVs, portable printers, portable scanners, and portable modems, mechanical wristwatches, pocket watches, pocket lights, hand mirrors, etc. Examples of components constituting the above portable electronic devices may include optical films or display panels used in image display devices such as thin-layer displays or film-shaped displays. The reinforcing film disclosed herein can also be preferably used in a manner where it is attached to various components in automobiles, home appliances, etc.

[0214] In addition, since the reinforcing film disclosed herein possesses bend recovery and bend retention capabilities, it can be preferably used in a manner that utilizes these characteristics by being attached to a component constituting a device equipped with a bendable element (e.g., a flexible device such as a flexible display; it may also be referred to as a rollable device or a foldable device). Examples of such devices include the various portable devices described above. Examples of components constituting the above portable electronic device may include optical films or display panels used in image display devices such as liquid crystal displays or organic EL (electroluminescence) displays. The reinforcing film disclosed herein can be preferably used for reinforcing a component constituting the device (typically an image display device referred to as a flexible device or a foldable device) in such portable electronic devices.

[0215] In addition, the reinforcing film disclosed herein is suitable for reinforcing optical members used as components of, for example, liquid crystal display panels, plasma display panels (PDP), organic EL displays, etc., during manufacturing, transport, etc. It is useful as a reinforcing film applied to optical members such as polarizers (polarizing films), wave plates, phase difference plates, optical compensation films, brightness enhancement films, light diffusion sheets, and reflective sheets for liquid crystal display panels.

[0216] Furthermore, the reinforcing film disclosed herein is not particularly limited in its application and can be used for various purposes intended to impart rigidity or impact resistance. The reinforcing film disclosed herein can be used not only for flexible device applications as described above, but also for other applications that do not involve flexible devices. The fact that the reinforcing film possesses bend recovery and bend retention capabilities implies that there are few limitations on the scope of application of said reinforcing film, and this offers significant practical advantages.

[0217] Examples

[0218] Several embodiments of the present invention are described below, but the present invention is not intended to be limited to these specific embodiments. Furthermore, "parts" and "%" in the following description are based on weight unless otherwise specified.

[0219] [Synthesis of Polymer (A)]

[0220] (Synthetic Example A1)

[0221] In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 90.2 parts of 2-ethylhexyl acrylate (2EHA), 8.6 parts of 4-hydroxybutyl acrylate (4HBA), 1.2 parts of N-acryloylmorpholine (ACMO), 0.2 parts of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator, and ethyl acetate as a polymerization solvent were added. Nitrogen gas was introduced while stirring gently, and the liquid temperature in the flask was maintained at around 65°C for 6 hours to carry out a polymerization reaction, thereby preparing an acrylic polymer A1 solution with a polymer concentration of 35%. The weight average molecular weight (Mw) of the acrylic polymer A1 was 540,000.

[0222] (Synthetic Example A2)

[0223] A solution polymerization was performed in the same manner as Synthesis Example A1, except that the monomer composition was changed to 2EHA / 4HBA / ACMO / butyl acrylate (BA) = 86.1 parts / 9.7 parts / 1.8 parts / 2.4 parts, thereby obtaining a solution of acrylic polymer A2.

[0224] (Synthesized Example A3)

[0225] A solution of acrylic polymer A3 was obtained by performing solution polymerization in the same manner as Synthesis Example A1, except that the monomer composition was changed to BA / 4HBA=96 parts / 4 parts.

[0226] (Synthetic Example A4)

[0227] A solution polymerization was performed in the same manner as Synthesis Example A1, except that the monomer composition was changed to 2EHA / 2-hydroxyethyl acrylate (HEA) / methyl methacrylate (MMA) / N-vinyl-2-pyrrolidone (NVP) = 65 parts / 15 parts / 7 parts / 13 parts, thereby obtaining a solution of acrylic polymer A4.

[0228] [Synthesis of Polymer (B)]

[0229] (Synthetic Example B1)

[0230] 101.15 parts ethyl acetate, 40 parts MMA, 20 parts n-butyl methacrylate (nBMA), 20 parts 2-ethylhexyl methacrylate (2EHMA), 8.7 parts polyorganosiloxane backbone-containing methacrylate monomer with a functional group equivalent of 900 g / mol (product name: X-22-174ASX, manufactured by Shin-Etsu Kagaku Kogyo Co., Ltd.), 11.3 parts polyorganosiloxane backbone-containing methacrylate monomer with a functional group equivalent of 4600 g / mol (product name: KF-2012, manufactured by Shin-Etsu Kagaku Kogyo Co., Ltd.), and 0.8 parts thioglycerol as a chain transfer agent were added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, a condenser, and a dropping funnel. Then, after stirring for 30 minutes under a nitrogen atmosphere at 70°C, 0.2 parts of AIBN were added as a thermal polymerization initiator, and the reaction was carried out at 70°C for 3 hours. After stirring at 80°C for 30 minutes, an additional 0.1 parts of AIBN were added, and the reaction was carried out at 80°C for 2 hours. Subsequently, an additional 0.05 parts of AIBN were added, and the reaction was carried out at 80°C for 2 hours to obtain polymer B1. The Mw of the obtained polymer B1 is 20,000, and Tg (T B ) was -13.8℃.

[0231] (Synthesized Examples B2 to B6)

[0232] Polymers B2 to B6 were prepared in the same manner as polymer B1, except that the composition of the monomer components was changed as shown in Table 1. The Tg (T BPolymer B2 was -8.4℃, Polymer B3 was -7.2℃, Polymer B4 was -0.6℃, Polymer B5 was -25.1℃, and Polymer B6 was 9.4℃. In Table 1, MMA is methyl methacrylate (Tg 105℃), nBMA is n-butyl methacrylate (Tg 20℃), 2EHMA is 2-ethylhexyl methacrylate (Tg -10℃), iBMA is isobutyl methacrylate (Tg 48℃), CHMA is cyclohexyl methacrylate (Tg 66℃), X-22-174ASX is a polyorganosiloxane backbone-containing methacrylate monomer (trade name: X-22-174ASX, manufactured by Shin-Etsu Kagaku Kogyo Co., Ltd., functional group equivalent 900 g / mol), KF-2012 is a polyorganosiloxane backbone-containing methacrylate monomer (trade name: KF-2012, manufactured by Shin-Etsu Kagaku Kogyo Co., Ltd., functional group equivalent 4600 g / mol), Each represents a different aspect.

[0233] Composition of monomer components used in the preparation of polymers B1 to B6 and Tg (T B ) is integrated and shown in Table 1.

[0234]

[0235] In addition, the Mw of each of the aforementioned polymers was determined by polystyrene conversion by measuring under the following conditions using a GPC device (Dosoh Co., Ltd., HLC-8220GPC).

[0236] [GPC Conditions]

[0237] ㆍSample concentration: 0.2 wt% (tetrahydrofuran (THF) solution)

[0238] ㆍSample injection volume: 10μl

[0239] ㆍEluent: THF

[0240] ㆍFlow rate: 0.6 ml / min

[0241] ㆍMeasured temperature: 40℃

[0242] Column:

[0243] Sample Column; TSKguardcolumn SuperHZ-H(1)+TSKgel SuperHZM-H(2)

[0244] Reference Column; TSKgel SuperH-RC (1 unit)

[0245] Detector: Differential Refractometer (RI)

[0246] [Production of Reinforcement Film]

[0247] <Example 1>

[0248] 100 parts of acrylic polymer A1, 2.0 parts of polymer B1, and 0.10 parts of isocyanate compound C1 (product name "Coronate HX", manufactured by Dosoh Co., Ltd.) as a crosslinking agent in terms of solid content were added, and the solution was diluted with ethyl acetate so that the total solid content was 30% to obtain an acrylic adhesive solution according to the present example.

[0249] A release liner (product name "Diafoil MRF75", manufactured by Mitsubishi Chemical Co., Ltd.) made of polyester resin with a thickness of 75 μm and silicone treatment on one side was prepared, and the acrylic adhesive solution obtained above was applied to the silicone-treated surface and dried at 130°C for 1 minute to form an adhesive layer with a thickness of 25 μm.

[0250] Next, a polyimide substrate with a thickness of 50 μm (product name "U-Fillers 50S", manufactured by Ube Kosan Co., Ltd.) was bonded to the surface of the obtained adhesive layer to obtain a reinforcing film according to the present example. This reinforcing film has an adhesive layer on one side of the substrate and takes the form of an adhesive sheet equipped with a release liner in which the release surface of the release liner is in contact with the adhesive surface.

[0251] In addition, for the reinforcing film of the present example, the molar ratio ([NCO] / [OH]) was calculated from the amount of OH (moles of hydroxyl groups in acrylic polymer A1) and the amount of NCO (moles of isocyanate groups in isocyanate compounds) in the adhesive layer, and it was 0.008.

[0252] <Examples 2 to 3>

[0253] Acrylic adhesive solutions for each example were obtained in the same manner as in Example 1, except that polymer B2 (Example 2) and polymer B3 (Example 3) were used instead of polymer B1. Reinforcing films for each example were prepared in the same manner as the reinforcing film for Example 1, except that each of these acrylic adhesive solutions was used.

[0254] <Examples 4 to 7>

[0255] Acrylic adhesive solutions for each example were obtained in the same manner as in Example 1, except that the amount of isocyanate compound C1 used was changed to 0.015 parts (Example 4), 0.05 parts (Example 5), 0.20 parts (Example 6), and 0.60 parts (Example 7) in terms of solid content per 100 parts of acrylic polymer A1, as shown in Table 2. Reinforcement films for each example were prepared in the same manner as the reinforcement film for Example 1, except that each of these acrylic adhesive solutions was used.

[0256] <Examples 8 to 10>

[0257] Acrylic adhesive solutions for each example were obtained in the same manner as in Example 1, except that the amount of polymer B1 used was changed to 1.0 parts (Example 8), 3.0 parts (Example 9), and 6.0 parts (Example 10) per 100 parts of acrylic polymer A1, as shown in Table 2. Reinforcement films for each example were produced in the same manner as the reinforcement film for Example 1, except that each of these acrylic adhesive solutions was used.

[0258] <Example 11>

[0259] An acrylic adhesive solution according to the present example was obtained in the same manner as in Example 1, except that acrylic polymer A2 was used instead of acrylic polymer A1. A reinforcing film according to the present example was produced in the same manner as in Example 1, except that the obtained acrylic adhesive solution was used.

[0260] <Example 12>

[0261] An acrylic adhesive solution according to the present example was obtained in the same manner as in Example 1, except that acrylic polymer A3 was used instead of acrylic polymer A1, and isocyanate compound C2 (trade name "Takenate D110N", manufactured by Mitsui Chemical Co., Ltd.) was used as a crosslinking agent in an amount of 0.07 parts in terms of solid content per 100 parts of acrylic polymer A3. A reinforcing film according to the present example was produced in the same manner as the reinforcing film according to Example 1, except that the obtained acrylic adhesive solution was used.

[0262] <Example 13>

[0263] An acrylic adhesive solution according to the present example was obtained in the same manner as in Example 12, except that the amount of isocyanate compound C2 used was changed to 0.09 parts in terms of solid content per 100 parts of acrylic polymer A3, as shown in Table 2. A reinforcing film according to the present example was produced in the same manner as the reinforcing film according to Example 1, except that the obtained acrylic adhesive solution was used.

[0264] <Comparative Examples 1 and 2>

[0265] Acrylic adhesive solutions for each example were obtained in the same manner as in Example 1, except that polymer B5 (Comparative Example 1) and polymer B6 (Comparative Example 2) were used instead of polymer B1. Reinforcing films for each example were prepared in the same manner as in Example 1, except that each of these acrylic adhesive solutions was used.

[0266] <Comparative Example 3>

[0267] An acrylic adhesive solution according to the present example was obtained in the same manner as in Example 1, except that acrylic polymer A4 was used instead of acrylic polymer A1, and isocyanate compound C2 (trade name "Takenate D110N", manufactured by Mitsui Chemical Co., Ltd.) was used as a crosslinking agent in an amount of 0.50 parts in terms of solid content per 100 parts of acrylic polymer A4. A reinforcing film according to the present example was produced in the same manner as the reinforcing film according to Example 1, except that the obtained acrylic adhesive solution was used.

[0268] <Comparative Examples 4 to 5>

[0269] Acrylic adhesive solutions for each example were obtained in the same manner as Comparative Example 3, except that the amount of isocyanate compound C2 used was changed to 1.10 parts (Comparative Example 4) and 2.50 parts (Comparative Example 5) in terms of solid content per 100 parts of acrylic polymer A4, as shown in Table 2. Reinforcement films for each example were prepared in the same manner as the reinforcement film for Example 1, except that each of these acrylic adhesive solutions was used.

[0270] <Example 14>

[0271] An acrylic adhesive solution according to the present example was obtained in the same manner as in Example 1, except that polymer B4 was used instead of polymer B1. A reinforcing film according to the present example was produced in the same manner as in Example 1, except that the obtained acrylic adhesive solution was used.

[0272] <Evaluation>

[0273] [Surface Modulus]

[0274] For the reinforcing film for each example, aging was performed at 50°C for 1 day, and the surface elastic modulus was measured. The release liner protecting the adhesive surface was peeled off, and an indenter was pressed into the surface of the adhesive layer to a depth of 6 μm using a nanoindenter device (Triboindenter manufactured by Hysitron Inc.), and the maximum load (Pmax) [GPa / mm²] was measured by the nanoindenter. 2 ] obtained. This, Equation:

[0275] Surface hardness [GPa] = Pmax / A

[0276] By substituting into the equation, the surface hardness was calculated, converted to [kPa] units, and recorded as the surface elastic modulus at 23°C (23°C surface elastic modulus). The measurement conditions are as follows. In addition, in the above equation, A is the contact projected area of ​​the indenter [mm² 2 ]am.

[0277] (Measurement conditions)

[0278] Indenter approach speed: 5㎛ / s

[0279] Maximum displacement: 6㎛

[0280] Indentation speed: 5㎛ / s

[0281] Subtraction rate: 5㎛ / s

[0282] Indenter used: Conical (Spherical indenter: Radius of curvature 10㎛)

[0283] Measurement method: Single indentation measurement

[0284] Measured temperature: Room temperature (23℃)

[0285] [Bulk modulus G' and tanδ]

[0286] A release liner R1 (product name "Diafoil MRF75", manufactured by Mitsubishi Chemical Co., Ltd.) made of polyester resin with a thickness of 75 μm and silicone treated on one side was prepared, and an acrylic adhesive solution according to each example was applied to the silicone-treated surface and dried at 130°C for 1 minute to form an adhesive layer with a thickness of 25 μm. Subsequently, a release liner R2 (product name "Diafoil MRE75", manufactured by Mitsubishi Chemical Co., Ltd.) made of polyester resin with a thickness of 75 μm and silicone treated on one side was coated on the surface of the obtained adhesive layer with the silicone-treated surface facing the adhesive layer, and aging was performed at 50°C for 1 day.

[0287] Only the obtained adhesive layer was removed and laminated to a thickness of about 1 mm, and this was punched to φ8 mm to produce a cylindrical pellet, which was used as a sample for measurement.

[0288] The above measurement sample was fixed to a jig on a φ8 mm parallel plate, and the storage modulus G', loss modulus G", and loss tangent tanδ were measured under the following conditions using a dynamic viscoelasticity measuring device (T.A. Instruments "ARES"), and the storage modulus G' at 23°C 23 [kPa], storage modulus G' at 80°C 80 [kPa] and tanδ at 80°C (loss modulus G at 80°C) 80 Storage modulus G' at 80℃ 80 ) was obtained.

[0289] · Measurement mode: Shear mode

[0290] · Temperature range: -70℃ to 200℃

[0291] · Heating rate: 5℃ / min

[0292] · Frequency: 1Hz

[0293] Furthermore, the storage modulus G' corresponds to the portion stored as elastic energy when the material deforms and is an indicator of the degree of hardness. The loss modulus G' corresponds to the portion of energy dissipated due to internal friction, etc., when the material deforms and indicates the degree of viscosity.

[0294] [Initial Adhesion]

[0295] For each example, the reinforcing film was aged at 50°C for 1 day, and the film was cut with the release liner to a width of 25 mm × a length of 140 mm to be used as a measurement sample. The release liner was peeled off from the measurement sample to expose the adhesive surface, and a 2 kg hand roller was used to press it against a stainless steel plate (SUS304BA plate) as a substrate by moving it back and forth once. After the measurement sample pressed onto the substrate in this manner was left at an ambient temperature of 23°C for 30 minutes, the load was measured when the reinforcing film was peeled from the substrate using a tensile testing machine (manufactured by Shimadzu Seisakusho, product name “Autograph AG-Xplus HS 6000 mm / min high-speed model (AG-50NX plus)”) under conditions of a peel angle of 180 degrees and a peel speed (tensile speed) of 300 mm / min, and the average load at the time of measurement was recorded as the initial adhesive strength [gf / 25 mm].

[0296] [Adhesion after heating]

[0297] For the reinforcing film for each example, a measurement sample was prepared in the same manner as the initial adhesion strength measurement above and pressed onto a substrate. Then, the measurement sample pressed onto the substrate was heated for 60 minutes at an ambient temperature of 60°C. After that, it was left for 30 minutes at an ambient temperature of 23°C, and the load was measured when the reinforcing film was peeled from the substrate using a tensile testing machine (manufactured by Shimadzu Seisakusho, product name "Autograph AG-Xplus HS 6000 mm / min high-speed model (AG-50NX plus)") under conditions of a peel angle of 180 degrees and a peel speed (tensile speed) of 300 mm / min. The average load at the time of measurement was recorded as the adhesion strength after heating [gf / 25 mm].

[0298] [Flexibility Retention Test]

[0299] For the reinforcing film for each example, after aging at 50°C for 1 day, the release liner was peeled off, and a polyimide substrate with a thickness of 25 μm (product name "U-Fillers 25S", manufactured by Ube Kosan Co., Ltd.) was bonded to the exposed adhesive surface and heated at 60°C for 60 minutes to bond them together. Subsequently, the obtained measurement sample (laminated) was fixed in a bent state with the 25 μm substrate side facing inward to a φ6 mm, and heated at 80°C for 15 hours. Then, it was left at room temperature (23°C), and after confirming that it had cooled sufficiently, the fixation of the measurement sample in the bent state was released, and within 10 minutes of the release, the bending angle [°] of the bent measurement sample was measured using a protractor to evaluate the bending recovery. In addition, the bending angle is the opening angle of the measurement sample (the angle of the side where the measurement sample opens from the bent state), and the closer it is to 180°, the better the bending recovery, and the closer the bending angle is to 0°, the worse the bending recovery.

[0300] Next, as an evaluation of flexural retention, the presence or absence of "drying" in the flexed portion of the measurement sample was visually checked; if no "drying" was visible, it was evaluated as "○," and if "drying" was visible, it was evaluated as "×."

[0301] The evaluation results for the reinforcing films for Examples 1 to 13 and Comparative Examples 1 to 5 are shown in Table 2. Table 2 also shows a schematic diagram of the composition of the adhesive layer for each example.

[0302]

[0303] In addition, the evaluation results of the bending recovery and recovery retention strength of the reinforcing film for Example 14 are shown in Table 3 along with the outline of Example 14 (composition and characteristics of the adhesive layer).

[0304]

[0305] As shown in Table 2, the adhesives according to Examples 1 to 13 comprise polymer (A) and polymer (B), and the Tg of the polymer (B) was within the range of -20°C to 5°C. The reinforcing films according to these examples provided a better balance between low initial adhesive strength and increased adhesive strength after heating compared to Comparative Examples 1 and 2, in which the Tg of the polymer (B) was outside the range of -20°C to 5°C. Furthermore, the reinforcing films according to Examples 1 to 13 had a surface elastic modulus of the adhesive layer at 23°C within the range of 1 to 20 kPa, and exhibited good flex recovery and flex retention. On the other hand, in Comparative Examples 3 to 5, in which the surface elastic modulus at 23°C was outside the range of 1 to 20 kPa, delamination was observed during the flex retention test.

[0306] More specifically, compared with Examples 1 to 3, as the Tg of the polymer (B) increased in the range of -20°C to 5°C, there was a tendency for the initial adhesive strength to decrease and the initial peelability to improve, while the adhesive strength after heating increased. On the other hand, in Comparative Example 1, where the Tg of the polymer (B) was less than -20°C, the initial adhesive strength was high and the peelability was poor. In addition, in Comparative Example 2, where the Tg of the polymer (B) was greater than 5°C, the increase in adhesive strength after heating was small. Furthermore, compared with Examples 4 to 7, it was confirmed that as the surface elastic modulus of the adhesive layer at 23°C increased in the range of 1 to 20 kPa, the bending recovery tended to improve, while the initial adhesive strength and adhesive strength after heating tended to decrease. Examples 5 to 7 showed superior bending recovery compared to Example 4, with a surface elastic modulus at 23°C of 2 kPa or more, and a tanδ at 80°C 80 This was within the range of 0.10 to 0.60. Furthermore, in Example 7, both the surface modulus and the bulk modulus were high values, resulting in a relatively lower increase in adhesive strength after heating compared to Examples 4 to 6. Additionally, in Examples 4 to 6, the bulk modulus G' of the adhesive layer at 23°C 23 No difference was observed. In addition, the bulk modulus G' at 80°C in Examples 1 to 3 and 5 80 The results were equivalent. With respect to Examples 1 to 7, the surface elastic modulus at 23°C was said to have a higher correlation with flexural recovery than with the bulk elastic modulus. In addition, in Examples 1 to 7, the molar ratio of isocyanate groups to hydroxyl groups ([NCO] / [OH]) in the adhesive layers of Examples 1 to 3 and 5 to 6, in which the initial tack, tack after heating, flexural recovery, and flexural holding power were improved in a better balance, was within the range of 0.002 to 0.03.

[0307] In addition, from the comparison of Examples 8 to 10, it was confirmed that as the amount of polymer (B) used increased, the adhesive strength tended to decrease. In Examples 8 to 9, where the amount of polymer (B) used was within the range of 0.5 to 5 parts per 100 parts of polymer (A), the initial adhesive strength was less than 400 gf / 25 mm, and the adhesive strength after heating was 500 gf / 25 mm or more, achieving better compatibility between light peelability at the beginning of application and the increase in adhesive strength after heating. Furthermore, as the amount of polymer (B) increased, the surface elasticity at 23°C increased, and the bending recovery tendency decreased. In addition, from the results of Examples 11 to 13, it was confirmed that the desired effect is achieved even if the type of polymer (A) of the adhesive or the type of crosslinking agent is changed.

[0308] In addition, as shown in Table 3, it was confirmed that flexural recovery and flexural retention are compatible in Example 14, which uses a polymer (B) with a Tg of -1.6°C and a surface elastic modulus of the adhesive layer at 23°C within the range of 1 to 20 kPa. Although not specifically indicated in the table, the reinforcing film according to Example 14 has an initial adhesive strength of less than 400 gf / 25 mm (specifically less than 200 gf / 25 mm), and an increase in adhesive strength after heating (adhesive strength increase ratio N 60 / N 23 ) is 7 (times), and it was to realize the effect of the technology disclosed here.

[0309] Although specific embodiments of the present invention have been described in detail above, they are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific embodiments exemplified above. Explanation of the symbols

[0310] 1, 2, 3: Reinforcing film 10: Supporting material 10A: 1st side 10B: 2nd side 21: Adhesive layer (first adhesive layer) 21A: Adhesive surface (first adhesive surface) 21B: Adhesive surface (second adhesive surface) 22: Adhesive layer (second adhesive layer) 22A: Adhesive surface (second adhesive surface) 31, 32: Release liner 100, 200, 300: Reinforcing film equipped with release liner

Claims

Claim 1 A reinforcing film comprising a support substrate and an adhesive layer laminated on one or both sides of the support substrate, wherein the support substrate is made of a resin film, and the adhesive layer comprises a polymer (A) and a polymer (B), wherein the polymer (A) is an acrylic polymer, wherein the acrylic polymer contains 50% by weight or more of a monomer unit derived from an alkyl meth)acrylate having a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms, wherein the ratio of a monomer unit derived from methyl methacrylate in the acrylic polymer is 6% by weight or less, and wherein the acrylic polymer contains a monomer unit derived from a hydroxyl group-containing monomer in a ratio of 1% by weight or more and 12% by weight or less, and wherein the polymer (B) comprises a monomer unit having a polyorganosiloxane backbone and a (meth)acrylic monomer unit, and wherein the adhesive layer comprises 0.015% by weight or more of an isocyanate-based crosslinking agent per 100% by weight of the polymer (A). It contains less than 0.5 parts by weight, and the adhesive layer does not contain a tackifying resin, or contains the tackifying resin in a ratio of less than 3 parts by weight per 100 parts by weight of the polymer (A), and the adhesive layer has a surface elastic modulus of 1 to 20 kPa at 23°C, and the glass transition temperature T of the polymer (B) B A reinforcing film having a temperature of -20℃ to 5℃. Claim 2 In claim 1, the adhesive layer has a bulk modulus of elasticity G' at 23°C 23 This is 10 to 200 kPa, and the bulk modulus of elasticity G' at 80°C 80 This is 5 to 100 kPa, and also tanδ at 80°C 80 A reinforcing film having a thickness of 0.10 to 0.

60. Claim 3 delete Claim 4 A reinforcing film according to claim 1 or 2, wherein the content of the polymer (B) in the adhesive layer is 0.5 to 5 parts by weight per 100 parts by weight of the polymer (A). Claim 5 A reinforcing film according to claim 1 or 2, wherein the molar ratio ([NCO] / [OH]) of isocyanate groups and hydroxyl groups included in the adhesive layer is 0.002 to 0.

03. Claim 6 An optical member to which a reinforcing film described in paragraph 1 or 2 is adhered. Claim 7 An electronic member to which a reinforcing film described in paragraph 1 or 2 is adhered.

Images