Enhanced thin films, optical components and electronic components

Abstract

This invention provides a reinforcing film that exhibits mild peel resistance in the initial stage of adhesion to an adherend, followed by a significant increase in adhesive strength, and also possesses flexural recovery and flexural retention properties. The reinforcing film includes an adhesive layer. The adhesive layer comprises a polymer (A) and a polymer (B). The polymer (B) comprises monomer units having a polyorganosiloxane backbone and (meth)acrylic acid monomer units. Furthermore, the adhesive layer has a surface elastic modulus of 1–20 kPa at 23°C.

Description

Technical Field

[0001] This invention relates to reinforcing films, and optical and electronic components to which the reinforcing films are adhered. This application claims priority to Japanese Patent Application No. 2020-134187, filed on August 6, 2020, the entire contents of which are incorporated herein by reference. Background Technology

[0002] For purposes such as bonding objects together and fixing articles to objects, adhesives are widely used in the form of adhesive sheets in various applications, including mobile phones, smartphones, tablet computers, and other electronic devices. For example, adhesive sheets are used as reinforcing materials (reinforcing films) to impart rigidity and impact resistance to optical components, electronic components, etc., constituting the aforementioned devices. Patent documents 1 and 2 disclose this prior art.

[0003] In addition, in recent years, portable electronic devices that can be bent or rolled up have attracted attention, and an adhesive sheet is being developed for fixing flexible devices (typically image display devices such as organic EL and liquid crystal display devices) built into such electronic devices (Patent Documents 3-6).

[0004] On the other hand, focusing on the performance of adhesives, an adhesive sheet has recently been proposed that exhibits low adhesive force in the initial stage of adhesion to the substrate, followed by a significant increase in adhesive force (Patent Document 7). According to an adhesive sheet with such characteristics, it can exhibit re-applying properties (reprocessing properties) useful for suppressing yield reduction caused by misapplication or damage of the adhesive sheet before the adhesive force increases, and exhibit strong adhesion suitable for the original purpose of the adhesive sheet after the adhesive force increases.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 6366199

[0008] Patent Document 2: Japanese Patent No. 6366200

[0009] Patent Document 3: Japanese Patent No. 6376271

[0010] Patent Document 4: Japanese Patent Application Publication No. 2016-108555

[0011] Patent Document 5: Japanese Patent Application Publication No. 2017-095657

[0012] Patent Document 6: Japanese Patent Application Publication No. 2017-095659

[0013] Patent Document 7: Japanese Patent No. 6373458 Summary of the Invention

[0014] The problem the invention aims to solve

[0015] Reinforcing films can also be used in the aforementioned flexible devices. For example, in the manufacture of such flexible devices, the components constituting the device are often relatively thin. Therefore, it is ideal to attach adhesive sheets as reinforcing films to prevent adverse conditions caused by device deformation or to improve operability. Since flexible devices can be repeatedly bent or flexed, the reinforcing films used in flexible devices are required to have the property of normally restoring their shape under repeated bending (bend recovery) and the property of not causing adverse conditions such as peeling (bend retention). Such reinforcing films with bend recovery and bend retention are useful because they can be used for various applications, including flexible devices, and therefore have fewer limitations in their scope of application.

[0016] For example, for adhesives such as those described in Patent Document 7, which exhibit low adhesive strength initially upon application followed by a significant increase in adhesive strength, it is ideal to possess flexural resilience and flexural retention when used as reinforcing films. One method to improve flexural retention is, for instance, to appropriately set the storage modulus of the adhesive. However, if the storage modulus of an adhesive designed to increase adhesive strength as described above is changed, both the initial low adhesive strength and the increased adhesive strength will be affected. Furthermore, when considering flexural resilience in addition to flexural retention, satisfying all these characteristics is not easy. For adhesives exhibiting low adhesive strength initially upon application followed by a significant increase in adhesive strength, improving both flexural resilience and flexural retention is beneficial in practical applications.

[0017] The present invention was made in view of the above-mentioned circumstances, and its object is to provide a reinforcing film that exhibits mild peelability in the initial stage of adhesion to the substrate, subsequently increases adhesive strength significantly, and possesses flexural recovery and flexural retention properties. Furthermore, another object of the present invention is to provide an optical component and an electronic component to which the above-mentioned reinforcing film is adhered.

[0018] Solution for solving the problem

[0019] According to this specification, a reinforcing film having an adhesive layer can be provided. The adhesive layer comprises polymer (A) and polymer (B). Polymer (B) comprises monomer units having a polyorganosiloxane backbone and (meth)acrylic acid monomer units. Furthermore, the surface elastic modulus of the adhesive layer at 23°C is 1–20 kPa.

[0020] Based on the above composition, the adhesive layer, containing a polymer (A) and a polymer (B) containing monomer units with a polyorganosiloxane backbone, exhibits mild peeling properties in the initial stage of adhesion to the substrate, followed by a significant increase in adhesive strength. Furthermore, the reinforcing film possesses flexural resilience and flexural retention. Specifically, reinforcing films with an adhesive layer having a surface elastic modulus at 23°C of 1 kPa or higher exhibit the aforementioned adhesive properties and good flexural resilience. Moreover, by setting the surface elastic modulus at 23°C of the adhesive layer to 20 kPa or less, the aforementioned adhesive properties are achieved, and good flexural retention is maintained, thus preventing peeling and other defects even when used in a repeatedly bent manner.

[0021] In some preferred embodiments of the technologies disclosed herein (including reinforcing films, optical components, and electronic components, hereinafter the same), the bulk modulus G' of the aforementioned adhesive layer at 23°C 23 The range is 10–200 kPa. The bulk modulus G', which falls within this range, is used. 23 The adhesive exhibits excellent initial adhesion strength, making it suitable for applications with good light peel properties. Furthermore, it demonstrates excellent processability, generally exhibiting a tendency to balance strain mitigation and flexural recovery at room temperature.

[0022] In some preferred embodiments, the bulk modulus G' of the aforementioned adhesive layer at 80°C 80 The range is 5–100 kPa. The bulk modulus G' within this range is... 80 Adhesives generally offer a good balance between flexural resilience and flexural retention. For example, even when used at high temperatures of around 80°C, they can maintain the elasticity suitable for flexural resilience while also possessing the adhesive retention strength necessary to achieve flexural retention.

[0023] In some preferred embodiments, the aforementioned adhesive layer is subjected to tanδ at 80°C. 80 The value is 0.10–0.60. The aforementioned tanδ 80 (Loss modulus G at 80℃) 80 Energy storage modulus G' at 80℃ 80 Adhesives with a tanδ value greater than 0.10 readily exhibit adhesive forces suitable for maintaining flexibility. Furthermore, by making the aforementioned tanδ... 80 With a value below 0.60, it easily suppresses the plastic deformation of the adhesive and achieves good flexural recovery. In addition, it easily exhibits holding force (flexural holding force) that prevents it from peeling off from the adherend when the reinforcing film is kept in a flexed state for a long time.

[0024] The aforementioned polymer (A) is preferably an acrylic polymer. By using an adhesive layer comprising polymer (A) as an acrylic polymer and polymer (B) containing monomer units having a polyorganosiloxane backbone, the effects of the technology disclosed herein can be preferably achieved.

[0025] In some preferred embodiments, the content of the aforementioned polymer (B) in the adhesive layer is 0.5 to 5 parts by weight relative to 100 parts by weight of the aforementioned polymer (A). By setting the amount of polymer (B) relative to 100 parts by weight of polymer (A) to 0.5 parts by weight or more, it is easy to obtain mild peeling properties in the initial stage of adhesion. By setting the amount of the aforementioned polymer (B) to 5 parts by weight or less, it is easy to achieve the desired increase in adhesive strength. Furthermore, by setting the amount of polymer (B) used within the above range, it is easy to achieve good flexural recovery and flexural holding force.

[0026] In some preferred embodiments, the molar ratio ([NCO] / [OH]) of isocyanate groups to hydroxyl groups in the aforementioned adhesive layer is 0.002 to 0.03. Adhesive layers with a molar ratio ([NCO] / [OH]) of 0.002 or higher tend to exhibit excellent flexural recovery and processability. Furthermore, by setting the molar ratio ([NCO] / [OH]) to 0.03 or lower, a suitable increase in adhesive strength is readily achieved. It should be noted that in the adhesive layer, the isocyanate groups and hydroxyl groups may exist in a state where at least a portion of them are chemically bonded (crosslinked). The aforementioned adhesive layer contains, for example, a crosslinking agent, in which 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).

[0027] In some preferred embodiments, the aforementioned binder layer comprises a catalyst. Furthermore, the molar ratio of the catalyst to hydroxyl groups ([catalyst] / [OH]) in the aforementioned binder layer is 1.0 × 10⁻⁶. -6 ~5.0×10 -2 By including a catalyst in an amount specified or higher relative to the amount of hydroxyl groups in the adhesive layer, the generation of bubbles in the adhesive layer can be suppressed, and a smooth adhesive surface can be easily obtained. Furthermore, by keeping the amount of catalyst used below a specified amount relative to the amount of hydroxyl groups in the adhesive layer, a suitable increase in adhesive strength can be easily achieved. The aforementioned catalyst is more preferably an iron-based catalyst, and the molar ratio of the aforementioned catalyst to hydroxyl groups in the aforementioned adhesive layer ([catalyst] / [OH]) is further preferably 1.0 × 10⁻⁶. -4 ~1.0×10 -3 .

[0028] The reinforcing films disclosed herein are suitable for imparting rigidity and impact resistance to optical components such as polarizers and wavelength plates during processing or transport. Therefore, according to this specification, an optical component with any of the reinforcing films disclosed herein adhered to it can be provided.

[0029] Furthermore, the reinforcing films disclosed herein are also suitable as reinforcing films for electronic components in machines such as portable electronic devices. Therefore, according to this specification, an electronic component with any of the reinforcing films disclosed herein attached can be provided. Attached Figure Description

[0030] Figure 1 A cross-sectional view illustrating the structure of a reinforcing film according to one embodiment is shown for illustrative purposes.

[0031] Figure 2 A cross-sectional view illustrating the structure of a reinforcing film according to another embodiment is shown for illustrative purposes.

[0032] Figure 3 A cross-sectional view illustrating the structure of a reinforcing film according to another embodiment is shown for illustrative purposes. Detailed Implementation

[0033] The preferred embodiments of the present invention will now be described. Matters necessary for carrying out the present invention other than those specifically mentioned in this specification can be understood by those skilled in the art based on the teachings on carrying out the invention as set forth in this specification and the technical common sense at the time of application. The present invention can be implemented based on the disclosures in this specification and the technical common sense in the field.

[0034] It should be noted that in the following figures, components or parts that perform the same function are sometimes labeled with the same symbols, and sometimes repeated descriptions are omitted or simplified. Furthermore, the embodiments described in the figures are schematic for the purpose of clearly illustrating the invention and may not accurately represent the dimensions or scale of the actual product provided.

[0035] Furthermore, in this specification, "acrylic polymer" refers to a polymer whose polymer structure contains monomer units derived from (meth)acrylic monomers, typically meaning a polymer containing monomer units derived from (meth)acrylic monomers in a proportion exceeding 50% by weight. Additionally, a (meth)acrylic monomer refers to a monomer having at least one (meth)acryloyl group in one molecule. Here, "(meth)acryloyl" includes both acryloyl and methacryloyl groups. Therefore, the concept of (meth)acrylic monomers here can include both monomers having an acryloyl group (acrylic monomers) and monomers having a methacryloyl group (methacrylic monomers). Similarly, in this specification, "(meth)acrylic acid" includes both acrylic acid and methacrylic acid, and "(meth)acrylate" includes both acrylate and methacrylate.

[0036] <Example of a reinforced thin film structure>

[0037] The reinforcing film disclosed herein has the form of an adhesive sheet, which has 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 can be in the form of an adhesive sheet with a substrate having the aforementioned adhesive layer laminated on one or both sides of a supporting substrate, or it can be in the form of an adhesive sheet without a supporting substrate. Hereinafter, the supporting substrate will sometimes be simply referred to as "substrate".

[0038] It should be noted that, in this specification, "reinforcing film" refers to the adhesive sheet (reinforcing adhesive film) used to reinforce adhered objects as described below. The reinforcing film can be, for example, in the form of a substrate-free adhesive sheet, with a support material or the like attached to one adhesive surface, and then the other adhesive surface attached to the adhered object to be reinforced. Therefore, it is not limited to the form of an adhesive sheet with a substrate. In this respect, it can be understood as a broader concept than the "reinforcing film" described below, which has the form of an adhesive sheet with a substrate.

[0039] The structure of the reinforcing film of one embodiment is schematically shown in... Figure 1 The reinforcing film 1 is constructed as a single-sided adhesive sheet with a substrate. The single-sided adhesive sheet with a substrate includes a sheet-like support substrate 10 having a first side 10A and a second side 10B, and an adhesive layer 21 disposed on the first side 10A. The adhesive layer 21 is fixed to the first side 10A of the support substrate 10. The reinforcing film 1 is used to attach the adhesive layer 21 to the object being adhered. Figure 1As shown, the reinforcing film 1 before use (i.e., before being attached to the substrate) can be a component of a reinforcing film 100 with a release liner. This reinforcing film 100 with a release liner is in the form of a release liner 31, where the surface (adhesive surface) 21A of the adhesive layer 21 abuts against at least one side opposite the adhesive layer 21, forming a peelable surface (release surface). As the release liner 31, it is preferable to use, for example, a release liner configured such that a release layer formed by a release agent is provided on one side of a sheet substrate (liner substrate), and that one side becomes the release surface. Alternatively, the release liner 31 can be omitted, and a support substrate 10 with the second side 10B as the release surface can be used, with the adhesive surface 21A abutting against the second side 10B of the support substrate 10 by rolling the reinforcing film 1 (roll form). When attaching the reinforcing film 1 to the substrate, the second side 10B of the release liner 31 or the support substrate 10 is peeled off from the self-adhesive surface 21A, and the exposed adhesive surface 21A is pressed onto the substrate.

[0040] The structure of the reinforcing film of another embodiment is schematically shown in Figure 2 The reinforcing film 2 is constructed as a double-sided adhesive sheet with a substrate. The double-sided adhesive sheet with a substrate includes a sheet-like support substrate 10 having a first side 10A and a second side 10B, an adhesive layer 21 disposed on the first side 10A, and an adhesive layer 22 disposed on the second side 10B. The adhesive layer (first adhesive layer) 21 is fixed to the first side 10A of the support substrate 10, and the adhesive layer (second adhesive layer) 22 is fixed to the second side 10B of the support substrate 10. The reinforcing film 2 is used to attach the adhesive layers 21 and 22 to different parts of the object being adhered. The parts where the adhesive layers 21 and 22 are attached can be individual parts of different components or different parts within a single component. Figure 2 As shown, the reinforcing film 2 before use can be a component of a reinforcing film 200 with a release liner. The reinforcing film 200 with a release liner is in the form of release liners 31 and 32, which are respectively formed by the surface of the adhesive layer 21 (first adhesive surface) 21A and the surface of the adhesive layer 22 (second adhesive surface) abutting against at least one side opposite to the adhesive layers 21 and 22, respectively. As the release liners 31 and 32, for example, release liners formed by providing a release layer formed by a release agent on one side of a sheet substrate (liner substrate) so that that one side becomes a release surface can be preferably used. Alternatively, the release liner 32 can be omitted, and a release liner 31 with release surfaces on both sides can be used. The second adhesive surface 22A is formed by overlapping it with the reinforcing film 2 and winding it into a spiral shape so that the reinforcing film with a release liner 31 abuts against the back side of the release liner 31 (roll shape).

[0041] The structure of the reinforcing film of another embodiment is schematically shown in Figure 3The reinforcing film 3 is constructed as a substrate-free double-sided adhesive sheet containing an adhesive layer 21. The reinforcing film 3 is used to attach 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 parts of the object being adhered. For example... Figure 3 As shown, the reinforcing film 3 before use can be a component of a reinforcing film 300 with a release liner. This reinforcing film 300 with a release liner has a first adhesive surface 21A and a second adhesive surface 21B abutting against release liners 31 and 32, which are respectively release surfaces on at least one side opposite to the adhesive layer 21. Alternatively, the release liner 32 can be omitted, and a release liner 31 with release surfaces on both sides can be used. By overlapping it with the reinforcing film 3 and winding it into a spiral shape, a reinforcing film with a release liner is formed in which the second adhesive surface 21B abuts against the back of the release liner 31 (roll shape).

[0042] It should be noted that the reinforcing film can be in roll form, in single sheet form, or cut or punched into suitable shapes according to its application and usage. The adhesive layer in the technology disclosed herein is typically formed continuously, but is not limited to this; for example, it can also be formed into regular or irregular patterns such as dots or stripes.

[0043] <Adhesive layer>

[0044] The reinforcing film disclosed herein comprises an adhesive layer containing polymer (A) and polymer (B). Such an adhesive layer can be formed from an adhesive composition containing polymer (A), which is a complete or partial polymer of monomer raw material A, and polymer (B). The form of the adhesive composition is not particularly limited, and can be various forms such as solvent-based, water-dispersible, hot-melt, and active energy radiation-cured (e.g., photocurable).

[0045] (Surface elastic modulus at 23℃)

[0046] The adhesive layer disclosed herein is characterized in that its surface elastic modulus (23°C surface elastic modulus) at 23°C is in the range of 1 to 20 kPa. By making the aforementioned surface elastic modulus at 23°C 1 kPa or more, adhesive properties based on polymers (A) and (B) can be achieved, and good flexural recovery can be obtained. Furthermore, by making the aforementioned surface elastic modulus 20 kPa or less, the aforementioned adhesive properties can be achieved, and good flexural holding force can be maintained.

[0047] From the viewpoint of improving flexural resilience, the aforementioned surface elastic modulus at 23°C is preferably 2 kPa or more, more preferably 3 kPa or more, 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). There is a tendency that the higher the aforementioned surface elastic modulus, the better the initial light peel resistance. Furthermore, from the viewpoint of balancing good flexural resilience and flexural holding force, and preferably exhibiting an increase in adhesive strength, the aforementioned 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, even more preferably 7 kPa or less (e.g., 6 kPa or less), and may also be 4 kPa or less.

[0048] The surface elastic modulus of the adhesive layer at 23°C can be adjusted by the type and properties (molecular weight, glass transition temperature, molecular structure, etc.) of polymer (A), the type and properties (molecular weight, glass transition temperature, etc.) of polymer (B), the amount used, and the type and amount of crosslinking agent. The surface elastic modulus of the adhesive layer at 23°C was measured by the method described in the following examples.

[0049] (bulk elastic modulus G' at 23℃) 23 )

[0050] Bulk modulus of elasticity G' of adhesive layer at 23°C 23 (bulk elastic modulus G' at 23℃) 23 The value can be appropriately set within the range that satisfies the above-mentioned surface elastic modulus at 23°C, and is not limited to a specific range. In some embodiments, the bulk elastic modulus G' of the adhesive layer at 23°C... 23 It is appropriate to set it to 10 kPa or higher. This is achieved by adjusting the aforementioned bulk modulus G'. 23 When set above the specified value, the initial adhesive force easily falls within a suitable range for excellent light peel performance. Furthermore, it exhibits excellent processability and generally tends to have excellent flexural recovery over a normal temperature range. The aforementioned bulk modulus G' 23 Preferably, the bulk modulus G' is 15 kPa or higher, more preferably 20 kPa or higher, even more preferably 25 kPa or higher, and particularly preferably 30 kPa or higher. 23 It can be above 50 kPa, above 80 kPa, or above 100 kPa.

[0051] In some methods, the bulk modulus of elasticity G' of the adhesive layer at 23°C 23 It is suitable to set it below 200 kPa. The above-mentioned bulk modulus G' 23Adhesives with a bulk modulus below the specified value generally exhibit excellent strain mitigation at room temperature and tend to show increased adhesive strength. The aforementioned bulk modulus G' 23 Preferably, the pressure is below 150 kPa, more preferably below 90 kPa. In some preferred embodiments, the above-mentioned bulk modulus G' 23 It can be below 60 kPa or below 40 kPa (e.g., below 35 kPa).

[0052] (80℃ bulk modulus of elasticity G') 80 )

[0053] Bulk modulus of elasticity G' of adhesive layer at 80°C 80 (80℃ bulk modulus of elasticity G') 80 The value is appropriately set within the range that satisfies the above-mentioned surface elastic modulus at 23°C, and is not limited to a specific range. In some embodiments, the bulk elastic modulus G' of the adhesive layer at 80°C is... 80 Preferably, it is 5 kPa or higher. This is achieved by adjusting the above-mentioned bulk modulus G'. 80 Setting it to a value above a specified level generally improves flexural resilience, allowing for suitable flexural recovery even under high-temperature conditions. In some preferred embodiments, the aforementioned bulk modulus G'... 80 It can be above 7 kPa, above 9 kPa, or above 10 kPa. In other embodiments, the aforementioned bulk modulus G' 80 It can be above 15 kPa, above 30 kPa, or above 50 kPa.

[0054] In some methods, the bulk modulus of elasticity G' of the adhesive layer at 80°C 80 It is suitable to set it below 100 kPa. This is achieved by adjusting the above-mentioned bulk modulus G'. 80 When limited to a specified value, good flexural holding force is generally easily obtained, and both flexural recovery and flexural holding force are easily balanced. For example, it can exhibit elasticity suitable for flexural recovery and adhesive holding force to achieve flexural holding force in various environments, including high-temperature conditions. The aforementioned bulk modulus G' 80 Preferably, the pressure is 90 kPa or less, more preferably 60 kPa or less. In some embodiments, the above-mentioned bulk modulus G' 80 It can be below 20 kPa, below 16 kPa, or below 14 kPa (e.g., below 12 kPa).

[0055] (80℃tanδ 80 )

[0056] tanδ of adhesive layer at 80°C 80 (80℃tanδ 80The value is appropriately set within the range that satisfies the aforementioned 23°C surface elastic modulus, and is not limited to a specific range. In some embodiments, the 80°C tanδ of the adhesive layer... 80 It is advisable to set it to 0.10 or higher. The above tanδ 80 The higher the value, the easier it is for the adhesive to exert a bonding force suitable for flexural retention. The above tanδ... 80 Preferably, it is 0.20 or higher. In some preferred embodiments, the above tanδ... 80 It can be above 0.30, above 0.40, or above 0.45.

[0057] In some methods, the adhesive layer is 80°C tanδ 80 Preferably, it is 0.60 or less. This is achieved by making the above tanδ... 80 A value below 0.60 can suppress plastic deformation of the adhesive and easily achieve good flexural recovery. Furthermore, when the reinforcing film is held in a bent state for an extended period, it easily maintains a holding force that prevents peeling from the adherend. Consequently, an increase in adhesive strength is also easily achieved within a suitable range. The above-mentioned 80℃ tanδ 80 It can be below 0.55. In other cases, the above-mentioned 80℃ tanδ 80 It can be below 0.50 or below 0.35.

[0058] The bulk modulus of elasticity G' of the adhesive layer at 23°C 23 80℃ bulk modulus of elasticity G' 80 and 80℃ tanδ 80 The modulus of elasticity of the adhesive layer at 23°C can be adjusted by the type and properties (molecular weight, glass transition temperature, molecular structure, etc.) of polymer (A), the type and properties (molecular weight, glass transition temperature, etc.) of polymer (B), the amount used, and the type and amount of crosslinking agent. 23 80℃ bulk modulus of elasticity G' 80 and 80℃ tanδ 80 The determination was performed using the method described in the following examples.

[0059] (Polymer(A))

[0060] As polymer (A), one or more of various polymers exhibiting rubber elasticity in the room temperature range, such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluoropolymers, which are well known in the adhesive field, can be used. In the reinforcing film disclosed herein, polymer (A) is typically the main component of the polymer composition contained in the adhesive layer, i.e., a component occupying more than 50% by weight, for example, a component occupying more than 75% by weight of the aforementioned polymer composition. In some embodiments, the aforementioned polymer (A) is a component occupying more than 50% by weight of the entire adhesive layer, a component occupying more than 70% by weight, a component occupying more than 80% by weight, a component occupying more than 90% by weight, or a component occupying more than 95% by weight (e.g., more than 97% by weight).

[0061] Glass transition temperature T of polymer (A) A Without particular limitation, the preferred properties can be obtained using the methods disclosed herein for enhancing the thin film. In some methods, T is preferred. A A polymer (A) with a temperature below 0°C. Adhesives containing such a polymer (A) are suitable for producing reinforcing films whose adhesive strength increases to a specified value upon heating due to their moderate fluidity (e.g., the mobility of the polymer chains contained in the adhesive). The reinforcing films disclosed herein can be made using T... A Polymer (A) with a temperature below -10°C, below -20°C, below -30°C, or below -35°C is preferred. In some embodiments, T A It can be below -40℃ or below -50℃. In some preferred methods, T A The temperature is below -55°C, more preferably below -58°C, even more preferably below -62°C, and may also be below -65°C (e.g., below -66°C). A There is no specific lower limit. From the perspective of material availability and improving the cohesive strength of the adhesive layer, T is generally preferred. A Polymers with temperatures above -80°C and above -70°C (A). In some methods, T A For example, it can be above -63℃, above -55℃, above -50℃, or above -45℃.

[0062] Here, in this specification, the glass transition temperature (Tg) of a polymer (e.g., the glass transition temperature of polymer (A), polymer (B) described below) refers to the nominal value recorded in literature, catalogs, etc., or the Tg calculated according to the Fox formula based on the composition of the monomer raw materials used to prepare the polymer. The Fox formula is shown below, which is the relationship between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer formed by homopolymerizing each of the monomers constituting the copolymer.

[0063] 1 / Tg=Σ(Wi / Tgi)

[0064] In the above Fox formula, Tg represents the glass transition temperature of the copolymer (in K), Wi represents the weight fraction of monomer i in the copolymer (weight-based copolymerization ratio), and Tgi represents the glass transition temperature of the homopolymer of monomer i (in K). When the target polymer for determining Tg is a homopolymer, the Tg of the homopolymer is consistent with the Tg of the target polymer.

[0065] The glass transition temperature (Tg) of homopolymers used for calculating Tg is the value recorded in well-known sources. Specifically, the values ​​are listed in the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989). For monomers for which multiple values ​​are recorded in the aforementioned Polymer Handbook, the highest value is used.

[0066] The glass transition temperature of homopolymers of monomers not described in the aforementioned polymer handbook is the value obtained by the following determination method.

[0067] 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 the polymerization solvent were added to a reactor equipped with a thermometer, stirrer, nitrogen inlet pipe, and reflux condenser. The mixture was stirred for 1 hour while nitrogen was flowing through it. After removing oxygen from the polymerization system, the temperature was raised to 63°C and the reaction was allowed to proceed for 10 hours. Then, the mixture was cooled to room temperature to obtain a homopolymer solution with a solids concentration of 33% by weight. This homopolymer solution was then cast onto a release liner and dried to produce a test sample (sheet-like homopolymer) approximately 2 mm thick. The test sample was punched into a disc shape with a diameter of 7.9 mm and clamped with parallel plates. While applying a shear strain of 1 Hz using a viscoelasticity testing machine (manufactured by TA Instruments Japan, model name "ARES"), the viscoelasticity was measured in shear mode at a heating rate of 5 °C / min in the temperature range of -70 °C to 150 °C. The temperature corresponding to the peak temperature of tanδ was set as the Tg of the homopolymer.

[0068] The weight-average molecular weight (Mw) of polymer (A) is typically suitable to be about 20 × 10⁻⁶. 4The above is not particularly limited. Using polymer (A) with this Mw, adhesives exhibiting good cohesiveness can be readily obtained. From the viewpoint of obtaining higher cohesive strength, in some preferred embodiments, the Mw of polymer (A) can be, for example, 30 × 10⁻⁶. 4 The above can be 40×10 4 The above can be 50×10 4 The above can be 60×10 4 The above can also be 80×10 4 That's all. Furthermore, the Mw of polymer (A) is typically suitable to be about 500 × 10⁻⁶. 4 The polymer (A) with the specified Mw is suitable for producing reinforcing films with low initial adhesion and high adhesion rise because it readily forms an adhesive exhibiting moderate flowability (mobility of polymer chains). It is also preferable that the Mw of polymer (A) is not too high from the viewpoint of improving compatibility with polymer (B). In some preferred embodiments, the Mw of polymer (A) may, for example, be 250 × 10⁻⁶. 4 The following can be 200×10 4 The following can be 150×10 4 The following can be 100×10 4 The following can also be 70×10 4 the following.

[0069] It should be noted that, in this specification, the Mw of polymer (A) and polymer (B) described below can be determined by polystyrene conversion using gel permeation chromatography (GPC). More specifically, Mw can be determined according to the methods and conditions described in the examples below.

[0070] Acrylic polymers are preferably used as the polymer (A) in the reinforcing film disclosed herein. Using an acrylic polymer as polymer (A) tends to readily achieve good compatibility with polymer (B). Good compatibility between polymer (A) and polymer (B) helps reduce initial adhesion and improve adhesion after heating by increasing the mobility of polymer (B) within the adhesive layer, thus being preferred. Furthermore, acrylic polymers with high molecular design freedom are suitable as adhesive materials that can evenly improve adhesive properties, flexural recovery, and flexural holding power.

[0071] Acrylic polymers may be, for example, polymers containing 50% by weight or more monomer units derived from alkyl (meth)acrylates, i.e., polymers in which 50% by weight or more of the total monomer components (monomer raw material A) used to prepare the acrylic polymer are alkyl (meth)acrylates. As the alkyl (meth)acrylate, it is preferable to use alkyl units having 1 to 20 carbon atoms (i.e., C... 1-20Alkyl (meth)acrylates with straight or branched alkyl groups. From the perspective of easily obtaining a balance of properties, monomer raw material A contains (meth)acrylate C. 1-20 The proportion of alkyl esters can be, for example, 50% by weight or more, or 60% by weight or more. In some preferred embodiments, the monomer raw material A contains (meth)acrylic acid C. 1-20 The proportion of alkyl ester is 70% by weight or more, more preferably 80% by weight or more, further preferably 85% by weight or more, and particularly preferably 90% by weight or more. By using the acrylic polymer composed of this monomer, it is easy to obtain an adhesive that balances adhesive strength increase with flexural recovery and flexural retention. Furthermore, the (meth)acrylic acid C in monomer raw material A... 1-20 The proportion of alkyl esters can be, for example, 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 esters may be, for example, 90% by weight or less, 85% by weight or less, or 80% by weight or less.

[0072] As (meth)acrylic acid C 1-20 Non-limiting examples of alkyl esters include: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and so on. Nonyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, undecyl acrylate, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, heptadecanyl acrylate, stearyl acrylate, isostearyl acrylate, nonadecanyl acrylate, eicosyl acrylate, etc.

[0073] Of these, it is preferred to use at least (meth)acrylic acid C. 1-18 Alkyl esters, more preferably using at least (meth)acrylic acid C 1-14 Alkyl esters. In some embodiments, acrylic polymers may contain C(meth)acrylate. 4-12 Alkyl esters (preferably C14 acrylic acid) 4-10 Alkyl esters, such as C14 acrylic acid 6-10At least one of alkyl esters is used as a monomer unit. For example, acrylic polymers containing one or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA) are preferred, and acrylic polymers containing at least 2EHA are particularly preferred.

[0074] In some preferred embodiments, acrylic acid C in monomer raw material A used to prepare acrylic polymers 6-10 Alkyl esters (suitable for acrylic acid C) 8-9 The proportion of alkyl esters (typically 2EHA) is 70% by weight or more, more preferably 80% by weight or more, further preferably 85% by weight or more, and particularly preferably 90% by weight or more. Acrylic polymers composed of this monomer are particularly suitable for achieving the effects of the technology disclosed herein. Furthermore, the acrylic acid C in monomer raw material A... 6-10 Alkyl esters (suitable for acrylic acid C) 8-9 The proportion of alkyl esters (typically 2EHA) can be, for example, 99.9% by weight or less, or 98% by weight or less, or 95% by weight or less, from the viewpoint of low initial adhesion and flexural recovery.

[0075] Furthermore, in some preferred embodiments, (meth)acrylic acid C is preferably restricted from monomer raw material A used to prepare acrylic polymers. 1-3 The proportion of alkyl esters (e.g., C1 alkyl esters of (meth)acrylate, typically methyl methacrylate (MMA)). C1 alkyl esters of (meth)acrylate 1-3 Alkyl esters (e.g., C1 alkyl esters of (meth)acrylate, typically MMA) tend to have relatively high Tg, and adhesives containing acrylic polymers using the aforementioned monomer components tend to have higher cohesiveness. This can be achieved by limiting the C1 alkyl esters of (meth)acrylate. 1-3 The amount of alkyl ester used can moderately reduce the cohesive force of the adhesive, preferably achieving an elastic modulus (typically surface elastic modulus) suitable for balancing flexural retention and increased adhesive strength. From this perspective, the (meth)acrylic acid C in the monomer raw material A mentioned above... 1-3 The proportion of alkyl esters (e.g., C1 alkyl methacrylate, typically MMA) is preferably set to 8% by weight or less, more 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).

[0076] Monomer raw material A may also contain alkyl (meth)acrylate as the main component and, if necessary, other monomers (copolymeric monomers) capable of copolymerizing with alkyl (meth)acrylate. Monomers with polar groups (e.g., carboxyl, hydroxyl, nitrogen-containing rings, etc.) are suitable as copolymeric monomers. Monomers with polar groups can help introduce crosslinking points into acrylic polymers or improve the cohesive strength of acrylic polymers. Copolymeric monomers may be used alone or in combination of two or more.

[0077] The following monomers can be cited as non-limiting examples of copolymerizable monomers.

[0078] Hydroxyl-containing monomers: such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl methacrylate, 10-hydroxydecyl methacrylate, 12-hydroxylaurate methacrylate, methyl methacrylate (4-hydroxymethylcyclohexyl) and other hydroxyalkyl methacrylates.

[0079] Monomers containing nitrogen-containing rings include, for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrrazine, N-vinylpyrrole, N-vinylimidazolium, 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-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisooxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine, etc.

[0080] For example, monomers with a succinimide skeleton such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyhexamethylenesuccinimide;

[0081] Examples of maleimides include N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; and

[0082] Examples of itconimides include N-methylitconimide, N-ethylitconimide, N-butylitconimide, N-octylitconimide, N-2-ethylhexylitconimide, N-cyclohexylitconimide, and N-laurylitconimide.

[0083] Monomers containing carboxyl groups: such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc.

[0084] Monomers containing anhydride groups: such as maleic anhydride and itaconic anhydride.

[0085] Epoxy-containing monomers: such as glycidyl acrylate (meth)acrylate, 2-ethyl glycidyl ether (meth)acrylate, and other epoxy-containing acrylates, allyl glycidyl ether, glycidyl ether (meth)acrylate, etc.

[0086] Cyano-containing monomers: such as acrylonitrile, methacrylonitrile, etc.

[0087] Monomers containing isocyanate groups: such as ethyl 2-isocyanate of (meth)acrylate, etc.

[0088] Amide-containing monomers: such as (meth)acrylamide; 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(tert-butyl)(meth)acrylamide, etc.; N-alkyl (meth)acrylamides such as N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, N-n-butyl (meth)acrylamide, etc.; N-vinylacetamide and other N-vinylcarboxylic acid amides; monomers having hydroxyl and amide groups, such as N-(2-hydroxy) N-hydroxyalkyl (methyl)acrylamides, such as N-(2-hydroxypropyl) (methyl)acrylamide, N-(1-hydroxypropyl) (methyl)acrylamide, N-(3-hydroxypropyl) (methyl)acrylamide, N-(2-hydroxybutyl) (methyl)acrylamide, N-(3-hydroxybutyl) (methyl)acrylamide, N-(4-hydroxybutyl) (methyl)acrylamide, etc.; monomers having alkoxy and amide groups, such as N-alkoxyalkyl (methyl)acrylamide, N-methoxyethyl (methyl)acrylamide, N-butoxymethyl (methyl)acrylamide, etc.; and N,N-dimethylaminopropyl (methyl)acrylamide, etc.

[0089] (Meth)acrylate aminoalkyl esters: for example, (meth)acrylate aminoethyl ester, (meth)acrylate N,N-dimethylaminoethyl ester, (meth)acrylate N,N-diethylaminoethyl ester, (meth)acrylate tert-butylaminoethyl ester.

[0090] Alkoxy-containing monomers: such as 2-methoxyethyl acrylate, 3-methoxypropyl acrylate, 2-ethoxyethyl acrylate, propoxyethyl acrylate, butoxyethyl acrylate, ethoxypropyl acrylate, etc. (meth)acrylate alkoxyalkyl esters; methoxyethylene glycol acrylate, methoxypolypropylene glycol acrylate, etc. (meth)acrylate alkoxyalkylene glycol esters.

[0091] Monomers containing sulfonic acid or phosphoric acid groups: such as styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonate, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamide propanesulfonic acid, (meth)acrylate sulfonyl propane, (meth)acryloyloxynaphthalene sulfonic acid, 2-hydroxyethylacryloyl phosphate, etc.

[0092] (Meth)acrylates with alicyclic hydrocarbon groups: for example, cyclopentyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentyl methacrylate, etc.

[0093] (Meth)acrylates containing aromatic hydrocarbon groups: for example, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, etc.

[0094] Vinyl ethers: such as methyl vinyl ether, ethyl vinyl ether, and other vinyl alkyl ethers.

[0095] Ethylene esters: such as vinyl acetate, vinyl propionate, etc.

[0096] Aromatic vinyl compounds: such as styrene, α-methylstyrene, vinyltoluene, etc.

[0097] Olefins: such as ethylene, butadiene, isoprene, isobutene, etc.

[0098] In addition, heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogenated (meth)acrylates such as (meth)acrylates containing vinyl chloride or fluorine atoms, silicon-containing (meth)acrylates such as organosilicon (meth)acrylates, and (meth)acrylates obtained from terpene compound derivative alcohols, etc.

[0099] When using such a copolymeric monomer, its usage is not particularly limited, but it is generally suitable to be 0.01% by weight or more of monomer raw material A. From the viewpoint of better utilizing the effects produced by using the copolymeric monomer, the usage of the copolymeric monomer can be set to 0.1% by weight or more of monomer raw material A, or even 1% by weight or more. In some preferred embodiments, the content of the copolymeric monomer in monomer raw material A is 3% by weight or more, more preferably 5% by weight or more, and even more preferably 7% by weight or more (e.g., 8% by weight or more). There is a tendency that the higher the amount of copolymeric monomer used, the higher the cohesiveness and the higher the flexural recovery. In addition, the usage of the copolymeric monomer can be set to 50% by weight or less of monomer raw material A, preferably 30% by weight or less. This prevents the cohesive force of the adhesive from becoming too high and improves the tackiness at room temperature (25°C). In some preferred embodiments, the usage of the copolymeric monomer 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), or even 10% by weight or less. By limiting the amount of comonomers used, the cohesive force of the adhesive is reduced, the elastic modulus (typically the surface elastic modulus) becomes within a suitable range, excellent flexural holding force is easily obtained, and adhesive strength is easily increased.

[0100] In some embodiments, monomer raw material A may contain a monomer having a nitrogen-containing ring. By using a monomer having a nitrogen-containing ring, the cohesive force and polarity of the adhesive can be adjusted, making it suitable for improving the adhesive force after heating. By including a monomer having a nitrogen-containing ring in monomer raw material A, there is a tendency to improve the compatibility between the polymer (A) formed from the aforementioned monomer raw material A and the aforementioned polymer (B). As a result, it is easy to obtain a reinforcing film that can significantly increase the adhesive force upon heating.

[0101] Monomers having a nitrogen-containing ring can be suitably selected from the monomers exemplified above, used alone or in combination of two or more. 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 (meth)acryloyl groups as a monomer having a nitrogen-containing ring.

[0102] Specific examples of N-vinylcyclic amides include: N-vinyl-2-pyrrolidone, N-vinyl-2-piperidinone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholinedione. N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam are particularly preferred.

[0103] Specific examples of cyclic amides having a (meth)acrylyl group include: N-(meth)acryl-2-pyrrolidone, N-(meth)acryloperidine, N-(meth)acrylpyrrolidine, N-(meth)acrylmorpholine, etc. As a preferred example, N-acrylmorpholine (ACMO) is mentioned.

[0104] The amount of monomer containing nitrogen-containing atomic rings used is not particularly limited, but is generally suitable to be 40% by weight or less of monomer raw material A, and can be 30% by weight or less, 20% by weight or less, or 10% by weight or less. In some preferred embodiments, from the viewpoint of reducing cohesion and thus reducing elastic modulus (typically surface elastic modulus), the content of monomer containing nitrogen-containing atomic rings 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). Furthermore, the amount of monomer containing nitrogen-containing atomic rings used is generally 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). From the viewpoint of obtaining appropriate cohesion and elastic modulus, in some embodiments, the amount of monomer containing nitrogen-containing atomic rings used can be 0.8% by weight or more of monomer raw material A, or 1.0% by weight or more.

[0105] In some preferred embodiments, monomer raw material A comprises a hydroxyl-containing monomer. By using the hydroxyl-containing monomer, the cohesiveness, polarity, and consequently the elastic modulus (typically the surface elastic modulus) of the adhesive can be adjusted, preferably achieving the effects of the technology disclosed herein. Furthermore, the hydroxyl-containing monomer provides reaction sites with crosslinking agents (e.g., isocyanate-based crosslinking agents), thereby increasing the cohesiveness of the adhesive through crosslinking reactions.

[0106] As hydroxyl-containing monomers, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and N-(2-hydroxyethyl)(meth)acrylamide can be suitably used. Among these, 2-hydroxyethyl acrylate (HEA), 4-hydroxybutyl acrylate (4HBA), and N-(2-hydroxyethyl)acrylamide (HEAA) are preferred examples. From the viewpoint of obtaining cohesive strength suitable for flexural recovery and flexural retention, 4HBA is particularly preferred.

[0107] The amount of hydroxyl-containing monomer used is not particularly limited, but it is generally suitable to be 40% by weight or less of monomer raw material A, and can be 30% by weight or less, or 20% by weight or less. In some preferred embodiments, from the viewpoint of reducing cohesive strength and thus reducing elastic modulus (typically surface elastic modulus), the content of hydroxyl-containing monomer in monomer raw material A is 15% by weight or less, more preferably 12% by weight or less (e.g., 10% by weight or less). By limiting the amount of hydroxyl-containing monomer used, the mobility of polymer (B) in the adhesive layer is improved, and it is easier to achieve an increase in adhesive strength. In other embodiments, the content of hydroxyl-containing monomer can also be set to 5% by weight or less of monomer raw material A. Furthermore, the amount of hydroxyl-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, e.g., 0.5% by weight or more). From the viewpoint of obtaining adequate cohesive strength and elastic modulus, in some preferred embodiments, the amount of hydroxyl-containing monomer used is 1% by weight or more of monomer raw material A, more preferably 3% by weight or more, further preferably 5% by weight or more, and particularly preferably 7% by weight or more (e.g., 8% by weight or more).

[0108] In some embodiments, a monomer having a nitrogen-containing ring and a hydroxyl-containing monomer can be used in combination as comonomers. In this case, the total amount of the monomer having a nitrogen-containing ring and the hydroxyl-containing monomer can 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, further preferably 5% by weight or more, particularly preferably 7% by weight or more (e.g., 9% by weight or more), and can be 10% by weight or more, 15% by weight or more, 20% by weight or more, or 25% by weight or more. Furthermore, the total amount of the monomer having a nitrogen-containing ring and the hydroxyl-containing monomer can be, for example, 50% by weight or less of monomer raw material A, preferably 30% by weight or less. In some preferred embodiments, the total amount of the monomer having a nitrogen-containing ring and the hydroxyl-containing monomer 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).

[0109] In a monomer feedstock A comprising a monomer having a nitrogen-containing ring and a hydroxyl-containing monomer, the content (W) of the monomer having a nitrogen-containing ring in monomer feedstock A is... N ) and the content of hydroxyl-containing monomers (W OH The relationship between W and (weight standard) is not specifically defined. N / W OH For example, it can be 0.01 or higher, but is usually suitable to be 0.05 or higher, and can be 0.10 or higher, or even 0.12 or higher. In addition, W N / W OHFor example, it can be 10 or less, usually suitable to be 1 or less, preferably 0.50 or less, can be 0.30 or less, can be 0.20 or less, or can be 0.15 or less.

[0110] In some embodiments, monomer raw material A preferably does not contain monomers (monomer S1) having a polyorganosiloxane backbone, which can preferably be used as a component of monomer raw material B, or the content of such 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). Using monomer raw material A with such a composition, it is suitable to achieve a reinforcing film that balances good initial reprocessability with strong adhesion after the adhesion has increased. For the same reason, in other embodiments, monomer raw material A preferably does not contain monomer S1, or if it contains monomer S1, its content (by weight) is lower than the content of monomer S1 in monomer raw material B.

[0111] There are no particular limitations on the method for obtaining polymer A. Various polymerization methods can be appropriately employed, such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization. In some cases, solution polymerization is preferred. The polymerization temperature during solution polymerization can be appropriately selected based on the type of monomer and solvent used, as well as the type of polymerization initiator. For example, it can be set to approximately 20℃ to 170℃ (typically around 40℃ to 140℃).

[0112] The initiator used for polymerization can be appropriately selected from existing well-known thermal polymerization initiators, photopolymerization initiators, etc., depending on the polymerization method. A polymerization initiator can be used alone or in combination of two or more.

[0113] Examples of thermal polymerization initiators include azo-based polymerization initiators (e.g., 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionic acid) dimethyl ester, 4,4'-azobis-4-cyanovaleric acid, azobisisovalerate, 2,2'-azobis(2-amidinylpropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropanedisulfate), 2,2'-azobis(N,N'-dimethyleneisobutylamidinyl) dihydrochloride, etc.); persulfates such as potassium persulfate; peroxide-based polymerization initiators (e.g., benzoyl peroxide, tert-butyl maleate peroxide, lauroyl peroxide, etc.); and redox-based polymerization initiators. There is no particular limitation on the amount of thermal polymerization initiator. For example, it can be set to an amount in the range of 0.01 parts to 5 parts by weight, preferably 0.05 parts to 3 parts by weight, relative to 100 parts by weight of the monomer component (monomer raw material A) used in the preparation of the acrylic polymer.

[0114] There are no particular limitations on the photopolymerization initiator used. For example, benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-keto alcohol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzoyl-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators can be used. The amount of photopolymerization initiator used is not particularly limited; for example, it can be set to an amount in the range of 0.01 parts by weight to 5 parts by weight, preferably 0.05 parts by weight to 3 parts by weight, relative to 100 parts by weight of monomer raw material A.

[0115] In some embodiments, polymer A can be included in the adhesive composition for forming the adhesive layer in the form of a partial polymer (polymer slurry) obtained by irradiating a mixture of monomer raw material A, as described above, with ultraviolet light (UV) to polymerize a portion of that monomer component. The adhesive composition containing the polymer slurry can be applied to a specified substrate and irradiated with UV light to complete the polymerization. That is, the polymer slurry can be understood as a precursor of polymer A. The adhesive layer disclosed herein can be formed, for example, using an adhesive composition containing the polymer slurry and polymer B.

[0116] (Polymer(B))

[0117] The polymer (B) disclosed herein is a polymer comprising a monomer component (monomer raw material B) having a monomer having a polysiloxane backbone (hereinafter also referred to as "monomer S1") and a (meth)acrylic monomer. Polymer (B) may be referred to as a copolymer of monomer S1 and (meth)acrylic monomer. Polymer (B) may be used alone or in combination of two or more. Polymer (B), due to the low polarity and mobility of the polysiloxane structure derived from monomer S1, functions as an adhesive force retarder, suppressing initial adhesive force upon adhesion to the substrate and increasing adhesive force upon heating. As monomer S1, there is no particular limitation; any monomer containing a polysiloxane backbone may be used. Due to the low polarity derived from its structure, monomer S1 promotes the heavy presence of polymer (B) on the surface of the adhesive layer in the reinforcing film before use (before adhesion to the substrate), exhibiting mild peeling (low adhesion) in the initial stage of adhesion. As monomer S1, a monomer with a structure having a polymerizable reactive group at one end is preferably used. By comprising monomer S1 units and (meth)acrylic acid monomer units, a polymer (B) with a polyorganosiloxane backbone in its side chains is formed. This polymer (B) readily exhibits low initial adhesion and high adhesion upon heating due to the mobility and ease of movement of its side chains. Furthermore, in some embodiments, monomer S1 is preferably a monomer with a polymerizable reactive group at one end and no functional group at the other end that would crosslink with polymer (A). Polymer (B) copolymerized from monomer S1 of this structure readily exhibits low initial adhesion and high adhesion upon heating due to the mobility of the polyorganosiloxane structure derived from monomer S1.

[0118] As monomer S1, compounds represented by the following general formula (1) or (2) can be used, for example. More specifically, examples of single-terminal reactive silicone oils manufactured by Shin-Etsu Chemical Co., Ltd. include X-22-174ASX, X-22-2426, X-22-2475, KF-2012, etc. Monomer S1 can be used alone or in combination of two or more.

[0119]

[0120] Here, R in the above general formulas (1) and (2) 3 For hydrogen or methyl, R 4 It is a methyl or monovalent organic group, and m and n are integers greater than or equal to 0.

[0121] The functional group equivalent of monomer S1 can be an appropriate value within the range that allows the monomer S1 to achieve the desired effect, and is not limited to a specific range. From the viewpoint of sufficiently suppressing initial adhesion, the aforementioned functional group equivalent is, for example, 100 g / mol or more, or 200 g / mol or more, preferably 300 g / mol or more (e.g., 500 g / mol or more), more preferably 800 g / mol or more, and more preferably 1500 g / mol or more. In a particularly preferred embodiment, from the viewpoint of balancing low adhesion in the initial stage of adhesion with an increase in adhesion after heating, the aforementioned functional group equivalent is 2000 g / mol or more, and more 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 other embodiments, the aforementioned functional group equivalent may be 9000 g / mol or more, 12000 g / mol or more, or 15000 g / mol or more.

[0122] From the viewpoint of maximizing adhesive strength, the aforementioned functional group equivalent is preferably 30,000 g / mol or less, possibly 20,000 g / mol or less, possibly 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, possibly 4,200 g / mol or less, or possibly 3,500 g / mol or less. If the functional group equivalent of monomer S1 is within the above range, the compatibility within the adhesive layer (e.g., compatibility with the base polymer) is easily improved. Furthermore, the mobility of the polyorganosiloxane backbone (chain) of polymer (B) is good, making it easy to adjust the mobility of polymer (B) to a suitable range, and easily achieving an adhesive layer that balances low initial tackiness with increased adhesive strength after heating.

[0123] Here, "functional group equivalent" refers to the weight of the backbone (e.g., polydimethylsiloxane) bonded to an average of one functional group. The unit g / mol is used to convert to 1 mol of functional groups. The functional group equivalent of monomer S1 can be determined, for example, by nuclear magnetic resonance (NMR) analysis. 1 The spectral intensity is calculated from H-NMR (proton NMR). Based on 1 The functional group equivalent (g / mol) of monomer S1 in H-NMR spectral intensity can be calculated based on... 1 The usual structural analysis method for H-NMR spectroscopy analysis is performed as described in Japanese Patent No. 5951153, as needed. In the functional group equivalent of monomer S1, the aforementioned functional groups refer to polymerizable functional groups (e.g., (meth)acryloyl, vinyl, allyl, and other olefinic unsaturated groups).

[0124] It should be noted that when using two or more monomers with different functional group equivalents as monomer S1, the functional group equivalent of monomer S1 can be expressed as an arithmetic mean. That is, when n monomers with different functional group equivalents (monomer S11, monomer S12...monomer S1 ... n The functional group equivalent of monomer S1 can be calculated using the following formula.

[0125] Functional group equivalent of monomer S1 (g / mol) = (functional group equivalent of monomer S11 × amount of monomer S11 mixed with + functional group equivalent of monomer S12 × amount of monomer S12 mixed with + ... + monomer S1) n Functional group equivalent × monomer S1 n (the amount of compounded monomer S11) / (the amount of compounded monomer S12 + ... + monomer S1) n (mixing amount)

[0126] The content of monomer S1 can be appropriately selected within the range where the desired effect is achieved using monomer S1, and is not limited to a specific range. From the viewpoint of sufficiently suppressing initial adhesive force, in some embodiments, the content of monomer S1 in the total amount of monomer components (monomer raw material B) used to prepare polymer (B) can be, for example, 5% by weight or more. From the viewpoint of better exerting its effect as a delaying agent for the increase in adhesive force, it is preferably 10% by weight or more, more preferably 12% by weight or more, further preferably 15% by weight or more, particularly preferably 18% by weight or more, and may also be 20% by weight or more. Furthermore, from the viewpoint of polymerization reactivity and compatibility, the content of monomer S1 in monomer raw material B can be, for example, 80% by weight or less, preferably 60% by weight or less, preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 30% by weight or less. By setting the polymerization ratio of monomer S1 within an appropriate range, the increase in adhesive force can be appropriately manifested.

[0127] In addition to monomer S1, monomer raw material B also contains (meth)acrylic monomers capable of copolymerizing with monomer S1. By using one or more (meth)acrylic monomers, the mobility of polymer (B) within the adhesive layer can be suitably adjusted. Furthermore, it can also help improve the compatibility between polymer (B) and polymer (A). Polymer (B) containing (meth)acrylic monomer units is well compatible with acrylic polymers, thus easily achieving a reduction in initial adhesive strength and an increase in adhesive strength after heating by improving the mobility of polymer (B) within the adhesive layer.

[0128] In the polymer (B) used in the technology disclosed herein, the composition of the (meth)acrylic acid monomer contained in the monomer raw material B is preferably based on the glass transition temperature T of the (meth)acrylic acid monomer composition. B1Higher than the glass transition temperature T of polymer (A) A The method is set. T B1 For example, it can be set to above 0°C. Here, the glass transition temperature T is based on the composition of the (meth)acrylic monomers. B1 Tg refers to the Tg calculated using the Fox formula based solely on the composition of the (meth)acrylic monomers in the monomer components used to prepare polymer (B). B1 The glass transition temperature T can be calculated using only the (meth)acrylate monomers in the monomer composition used to prepare polymer (B), applying the above-mentioned Fox formula, based on the glass transition temperature of the homopolymer of each (meth)acrylate monomer and the weight fraction of each (meth)acrylate monomer in the total amount of that (meth)acrylate monomer. B1 Relatively high (typically above 0°C) polymers (B) tend to suppress initial adhesive forces. Furthermore, the glass transition temperature T... B1 Relatively high (typically above 0°C) polymers (B) readily yield reinforcing films with a large increase in adhesive strength.

[0129] In some preferred methods, T B1 The temperature is 10°C or higher, more preferably 30°C or higher, even more preferably 40°C or higher, and may also be 45°C or higher. If T B1 As the adhesion height increases, the initial adhesive force tends to be better suppressed. This is believed to be because, through T... B1 For polymer (B) at temperatures above a specified temperature, the increased mobility and fluidity of the polyorganosiloxane structural portion due to temperature rise to room temperature or a certain degree above room temperature is effectively suppressed by the monomer units derived from (meth)acrylic acid monomers contained in polymer (B), thus better maintaining the low adhesion obtained due to the presence of the aforementioned polyorganosiloxane structural portion. From the viewpoint of better maintaining the low adhesion during the initial adhesion stage, in some methods, T B1 For example, it can be above 50℃, above 55℃, or above 60℃. Furthermore, T B1 For example, it can be below 120℃ or below 100℃. If T... B1 As T decreases, there is a tendency for the adhesive strength to increase due to heating, which facilitates adhesion. In some preferred methods, T... B1 For example, the temperature is below 90°C, more preferably below 70°C, even more preferably below 60°C, and particularly preferably below 55°C (e.g., below 50°C).

[0130] From easy to play, by appropriately setting T B1From the perspective of the resulting effect, the total amount of monomer S1 and (meth)acrylic acid monomer in the total monomer composition used to prepare polymer (B) can 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, or substantially 100% by weight.

[0131] Glass transition temperature T of polymer (B) B Without particular limitation, the preferred properties can be obtained by means of the reinforced film disclosed herein. The T of polymer (B) B For example, the temperature can be below 50°C, below 30°C, below 20°C, below 15°C, or below 10°C. If the T of polymer (B) B As the temperature decreases, the mobility (typically thermosensitive mobility) of the polymer (B) increases, leading to a significant increase in adhesive strength. In some preferred embodiments, the Tg of the polymer (B) is... B The temperature can be below 5°C, less than 0°C, below -5°C, or below -10°C. Furthermore, in some methods, the T of polymer (B) B For example, it can be above -40℃ or above -30℃. T exists. B The higher the Tg, the more the polymer (B) that is more concentrated on the surface of the adhesive layer tends to help reduce initial adhesion and exhibit better initial peel strength when applied to the substrate. In some preferred embodiments, the Tg of polymer (B) is... B It can be above -20℃, or even above -15℃. By using T... B By setting the appropriate range, the initial peelability and the increase in adhesive strength after heating can be controlled to a preferred range.

[0132] In some methods, the composition of the monomer components used to prepare polymer (B) can be in T... B1 Higher than T B The method, namely T B1 -T B The temperature is set above 0°C. Based on this composition, the mobility of polymer (B) can be easily and appropriately adjusted by utilizing the composition of the (meth)acrylic monomers contained in the aforementioned monomer components. B1 -T B For example, it can be around 40℃ to 100℃, or around 50℃ to 90℃. In some preferred methods, 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). Furthermore, from the viewpoint of suitably exhibiting the effects of containing the polymer (B), T B1 -T BPreferably, the temperature is below 80°C, more preferably below 70°C, and even more preferably below 65°C (e.g., below 62°C).

[0133] From the viewpoint of easily controlling the mobility of polymer (B) within the adhesive layer, in some ways, the composition of the monomer components used to prepare polymer (B) can be related to the glass transition temperature T of polymer (A). A Relationship, T B T A Methods with temperatures above 20°C, i.e., T B -T A The setting is for temperatures above 20°C. In some preferred configurations, T... B -T A For example, the temperature is 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, and can be 60°C or higher, or 70°C or higher. Furthermore, from the viewpoint of increased adhesive strength, T... B -T A For example, the temperature can be below 130°C, below 120°C, preferably below 100°C, more preferably below 80°C, and even more preferably below 65°C. It can also be below 55°C or below 45°C.

[0134] Examples of (meth)acrylic monomers that can be used as monomer raw material B include, for example, alkyl (meth)acrylates. Here, "alkyl" refers to a chain-like (including straight-chain and branched) alkyl group, excluding the alicyclic hydrocarbon groups described below. For example, one or more monomers exemplified above as alkyl (meth)acrylates that can be used in polymer (A) can be used as constituents of monomer raw material B. In some embodiments, monomer raw material B may contain (meth)acrylate C. 4-12 Alkyl ester (preferably (meth)acrylic acid C) 4-10 Alkyl esters, such as (meth)acrylic acid C 6-10 At least one of alkyl esters. In other embodiments, monomer raw material B may contain methacrylic acid C. 1-18 Alkyl ester (preferably C methacrylate) 1-14 Alkyl esters, such as C-methacrylic acid 1-10 At least one of alkyl esters. Monomer raw material B may contain one or more of, for example, selected from MMA, n-butyl methacrylate (BMA) and 2-ethylhexyl methacrylate (2EHMA) as (meth)acrylic monomers.

[0135] Other examples of the aforementioned (meth)acrylate monomers include (meth)acrylates having an alicyclic hydrocarbon group. Examples include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, and 1-adamantyl (meth)acrylate. In some embodiments, monomer raw material B may contain at least one selected from dicyclopentyl methacrylate, isobornyl methacrylate, and cyclohexyl methacrylate as a (meth)acrylate monomer.

[0136] The content of the aforementioned alkyl (meth)acrylate and the aforementioned (meth)acrylate having alicyclic hydrocarbon groups in monomer raw material B can be, for example, 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 viewpoint of ease of increasing adhesive strength based on heating, the use of alkyl (meth)acrylate is advantageous. In some embodiments, the content of (meth)acrylate having alicyclic hydrocarbon groups 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. Alternatively, (meth)acrylate having alicyclic hydrocarbon groups may not be used.

[0137] In some preferred embodiments, the aforementioned (meth)acrylic acid monomers, which are components of monomer raw material B, may include monomer M2, whose homopolymer has a Tg of 50°C or higher. In polymer (B), by copolymerizing monomer S1 with monomer M2, the mobility and fluidity of the polyorganosiloxane structural portion accompanying temperature increases can be easily and appropriately controlled, while simultaneously achieving initial light peelability (reprocessability) 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. Furthermore, there is no particular upper limit to the Tg of the homopolymer of monomer M2; from the viewpoint of ease of synthesis of polymer (B), it is generally suitable to be below 200°C. In some embodiments, the Tg of the homopolymer of monomer M2 may, for example, be below 180°C, below 150°C, or below 120°C.

[0138] As monomer M2, for example, a monomer whose Tg of the homopolymer of the (meth)acrylic monomers exemplified above meets the requirements can be used. For example, one or more monomers selected from the group consisting of alkyl (meth)acrylates and (meth)acrylates having alicyclic hydrocarbon groups can be used. As an alkyl (meth)acrylate, an alkyl methacrylate with the number of carbon atoms in the alkyl group in the range of 1 to 4 is preferably used.

[0139] In the method where monomer raw material B includes monomer M2, the content of monomer M2 may be, for example, 5% by weight or more, 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 of monomer raw material B. In some methods, the content of monomer M2 may be 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, or 55% by weight or more of monomer raw material B. Furthermore, the content of monomer M2 may be, for example, 90% by weight or less, typically suitable to be 80% by weight or less, preferably 75% by weight or less, and may be 70% by weight or less, or may be 65% by weight or less. In some preferred methods, 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 polymer (B), by limiting the copolymerization ratio of monomer M2 with a Tg of 50°C or higher to a specified value or lower, an increase in adhesive strength after heating can preferably be achieved based on the mobility of polymer (B) near 50°C. From the same point of view, the content of monomer M2 in monomer raw material B can be 35% by weight or less, 25% by weight or less, or 15% by weight or less (e.g., 5% by weight or less).

[0140] The content of the aforementioned monomer M2 can preferably be applied in the following ways: monomer M2 comprises one or more monomers selected from the group consisting of alkyl methacrylates and methacrylates having alicyclic hydrocarbon groups; monomer M2 comprises one or more monomers selected from alkyl methacrylates (e.g., alkyl methacrylate). As a preferred example of this method, monomer M2 may comprise MMA.

[0141] In some embodiments, the aforementioned (meth)acrylic acid monomers may also include monomer M3, whose homopolymer Tg is less than 50°C (typically above -20°C and less than 50°C). By using monomer M3, it is easy to obtain a film that provides a balanced reinforcement of both adhesive and cohesive forces after the adhesive strength increases. From the viewpoint of easily achieving this effect, monomer M3 is preferably used in combination with monomer M2.

[0142] As monomer M3, for example, a monomer whose Tg of the homopolymer of the (meth)acrylic monomers exemplified above meets the requirements can be used. For example, one or more monomers selected from the group consisting of alkyl (meth)acrylic esters can be used.

[0143] In the method where monomer raw material B includes monomer M3, the content of monomer M3 may be, for example, 5% or more by weight of monomer raw material B, 10% or more by weight, 15% or more by weight, 20% or more by weight, 25% or more by weight, 30% or more by weight, or 35% or more by weight. Furthermore, the content of monomer M3 is generally preferably set to 70% or less by weight of monomer raw material B, and may be 60% or less by weight or 50% or less by weight. The aforementioned content of monomer M3 is preferably applied, for example, to a method where monomer M3 includes one or more monomers selected from alkyl methacrylates (e.g., alkyl methacrylates).

[0144] In some of the methods disclosed herein for reinforcing films, the monomer raw material B preferably contains 30% by weight or less of the monomer with a Tg higher than 170°C in the homopolymer. Here, unless otherwise specified, "monomer content of X% by weight or less" in this specification includes the possibility of the monomer content being 0% by weight, i.e., substantially not containing the monomer. Furthermore, "substantially not containing" means at least not intentionally using the aforementioned monomer. If the copolymerization ratio of monomers with a Tg higher than 170°C in the homopolymer becomes high, the mobility of polymer (B) is prone to insufficient, and sometimes it is difficult to increase the adhesive strength by heating to a temperature range higher than 50°C.

[0145] In some embodiments, monomer raw material B preferably contains at least MMA as a (meth)acrylic acid monomer. By copolymerizing the polymer (B) containing MMA, it is easy to obtain a reinforcing film with high adhesive strength after heating. The proportion of MMA in the total amount of (meth)acrylic acid monomers contained in monomer raw material B can be, for example, 5% by weight or more, 10% by weight or more, 20% by weight or more, 30% by weight or more, or 40% by weight or more. Furthermore, the proportion of MMA in the total amount of monomer raw material B is generally suitable to be 95% by weight or less. In some preferred embodiments, from the viewpoint of increased adhesive strength after heating, the proportion of MMA in the total amount of monomer raw material B can be 75% by weight or less, 65% by weight or less, 60% by weight or less, or 55% by weight or less (e.g., 50% by weight or less).

[0146] Other examples of monomers that can be contained together with monomer S1 as monomer units constituting polymer (B) include: monomers containing carboxyl groups, anhydride groups, hydroxyl groups, epoxy groups, cyano groups, isocyanate groups, amide groups, monomers having nitrogen-containing rings (N-vinyl cyclic amides, cyclic amides having (meth)acryloyl groups, monomers having succinimide skeletons, maleimides, itaconimides, etc.), aminoalkyl methacrylates, vinyl esters, vinyl ethers, olefins, (meth)acrylates having aromatic hydrocarbon groups, heterocyclic (meth)acrylates, (meth)acrylates containing halogen atoms, and (meth)acrylates obtained from terpene compound derivative alcohols, etc.

[0147] Further examples of monomers that can be contained together with monomer S1 as monomer units constituting polymer (B) include: 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, tripropylene glycol di(meth)acrylate, and other oxyalkylene di(meth)acrylates; monomers having a polyoxyalkylene backbone, such as those in polyethylene glycol, polypropylene glycol, etc. Polymerizable polyoxyalkylene ethers with a polymerizable functional group such as (meth)acryloyl, vinyl, or allyl at one end of the alkyl chain and an ether structure (alkyl ether, aromatic ether, arylalkyl ether, etc.) at the other end; methoxyethyl acrylate, ethoxyethyl acrylate, propoxyethyl acrylate, butoxyethyl acrylate, ethoxypropyl acrylate, and other alkoxyalkyl acrylates of (meth)acrylate; alkali metal salts of (meth)acrylate; trimethylolpropane tri(meth)acrylate, etc. Metamethacrylic esters: vinylidene chloride, 2-chloroethyl methacrylate, and other halogenated vinylidene compounds; monomers containing oxazoline groups, such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-isopropenyl-2-oxazoline; monomers containing aziridinium groups, such as aziridinium acrylate and 2-aziridinium ethyl methacrylate; 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, lactones, and adducts of 2-hydroxyethyl methacrylate, etc. These include hydroxyl-containing vinyl monomers; fluorinated vinyl monomers such as fluorinated alkyl (meth)acrylates; vinyl monomers containing reactive halogens such as 2-chloroethyl vinyl ether and vinyl monochloroacetate; vinyl monomers containing organosilicones such as vinyltrimethoxysilane, γ-(meth)acryloyloxypropyltrimethoxysilane, allyltrimethoxysilane, trimethoxysilylpropylallylamine, and 2-methoxyethoxytrimethoxysilane; and macromonomers with free radical polymerizable vinyl groups at the ends of the monomers containing vinyl groups. These can be copolymerized with monomer S1, either alone or in combination.

[0148] In some embodiments, polymer (B) is preferably a polymer that does not have functional groups that would react with polymer (A) to form a crosslinking reaction. In other words, polymer (B) is preferably contained in the adhesive layer in a form that is not chemically bonded to polymer (A). An adhesive layer containing polymer (B) in this form exhibits good mobility of polymer (B) upon heating, which is suitable for increasing the adhesive strength ratio. The functional groups that would react with polymer (A) to form a crosslinking reaction can vary depending on the type of functional groups possessed by polymer (A), and may be, for example, epoxy groups, isocyanate groups, carboxyl groups, alkoxysilyl groups, amino groups, etc.

[0149] The Mw of polymer (B) is not particularly limited. The Mw of polymer (B) can be, for example, 1000 or more, or 5000 or more. In some preferred embodiments, from the viewpoint of suitably exhibiting an increase in adhesive strength after heating, the Mw of polymer (B) can be 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 other embodiments, the Mw of polymer (B) can be 30,000 or more, 50,000 or more, or 70,000 or more. The upper limit of the Mw of polymer (B) is, for example, 500,000 or less, 350,000 or less, 200,000 or less, or 150,000 or less. From the viewpoint of adjusting the compatibility and mobility within the adhesive layer to a suitable range to appropriately exhibit low adhesion during the initial application, 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), and may be 25,000 or less, and even more preferably 20,000 or less. By setting the Mw of the polymer (B) to an appropriate range, an adhesive that achieves an excellent balance between light peeling and increased adhesion during the initial application can be easily obtained.

[0150] In some preferred embodiments, the Mw of polymer (B) is preferably lower than that of polymer (A). This facilitates the creation of a reinforcing film that balances good reprocessability during initial application with increased adhesive strength after heating. In some embodiments, the Mw of polymer (B) may be, for example, less than 0.8 times, less than 0.75 times, less than 0.5 times, or less than 0.3 times the Mw of polymer (A). In some preferred embodiments, the Mw of polymer (B)... B Mw relative to polymer (A) A The ratio (Mw) B / Mw A The content of (Mw) is 0.3 or less, more preferably 0.2 or less, further preferably 0.1 or less, and particularly preferably 0.06 or less (e.g., 0.05 or less). Furthermore, the ratio of (Mw) to... B / Mw A For example, it is suitable to be 0.010 or more, preferably 0.020 or more, more preferably 0.03 or more, and even more preferably 0.04 or more. By setting the Mw of polymer (A) and the Mw of polymer (B) within suitable ranges, the effects of the technology disclosed herein can be better achieved. In other embodiments, the Mw of polymer (B) may also be less than 0.03 times (e.g., less than 0.02 times) of the Mw of polymer (A).

[0151] Polymer (B) can be produced, for example, by polymerizing the aforementioned monomers using known methods such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization.

[0152] To adjust the molecular weight of polymer (B), chain transfer agents can be used as needed. Examples of chain transfer agents that can be used include: compounds with thiol groups such as octylthiol, laurylthiol, tert-nonylthiol, tert-dodecylthiol, mercaptoethanol, and α-thioglycerol; thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, tert-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, thioglycolate esters of ethylene glycol, neopentyl glycol, and pentaerythritol; and α-methylstyrene dimers, etc.

[0153] The amount of chain transfer agent used is not particularly limited, but typically it is 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, relative to 100 parts by weight of the monomer. By adjusting the amount of chain transfer agent added in this way, a polymer (B) with a suitable molecular weight can be obtained. One chain transfer agent can be used alone or in combination of two or more.

[0154] As a means of adjusting the molecular weight of polymer (B), various existing and known methods, including the use of the aforementioned chain transfer agent, can be used alone or in appropriate combinations. The same applies to the molecular weight of polymer (A). Non-limiting examples of such methods include the selection of the polymerization method, the type and amount of the polymerization initiator, the selection of the polymerization temperature, the type and amount of the polymerization solvent in solution polymerization, and the selection of the light irradiation intensity in photopolymerization. Those skilled in the art, based on the description in this application containing the specific examples below and the technical common sense at the time of filing, can understand how to obtain polymers with desired molecular weights.

[0155] In the reinforcing film disclosed herein, the amount of polymer (B) used relative to 100 parts by weight of polymer (A) can be, for example, 0.1 parts by weight or more. From the viewpoint of obtaining a higher effect (suitable for light peeling during the initial stage of adhesion), it is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, even more preferably 1.5 parts by weight or more, and may also be 2 parts by weight or more. In some embodiments, from the viewpoint of improving reprocessability, the amount of polymer (B) used may be, for example, 3 parts by weight or more, 4 parts by weight or more, or 5 parts by weight or more. Furthermore, relative to 100 parts by weight of polymer (A), the amount of polymer (B) used may 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. From the viewpoint of achieving the desired increase in adhesive strength, in some preferred embodiments, relative to 100 parts by weight of polymer (A), the amount of polymer (B) used 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 other preferred embodiments, the amount of polymer (B) used is 1.5 parts by weight or less (e.g., 1.2 parts by weight or less) relative to 100 parts by weight of polymer (A). By setting the amount of polymer (B) within the above range, good flexural recovery and flexural holding force can be easily achieved. In addition, mild peeling and adhesion rise during the initial application can be better balanced.

[0156] The adhesive layer may, as needed, contain polymers other than polymer (A) and polymer (B) (any polymer) without significantly impairing the performance of the reinforcing film disclosed herein. The amount of such arbitrary polymer used is typically suitable to be 20% by weight or less, 15% by weight or less, or 10% by weight or less of the total polymer component contained in the adhesive layer. In some embodiments, the amount of the aforementioned arbitrary polymer may be 5% by weight or less, 3% by weight or less, or 1% by weight or less of the total polymer component. An adhesive layer may also be substantially free of polymers other than polymer (A) and polymer (B).

[0157] (Cross-linking agent)

[0158] In the adhesive layer, a crosslinking agent may be used as needed for purposes such as adjusting cohesion. Crosslinking agents known in the adhesive field can be used, such as epoxy crosslinking agents, isocyanate crosslinking agents, silicone crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyl etherified melamine crosslinking agents, and metal chelate crosslinking agents. Isocyanate crosslinking agents, epoxy crosslinking agents, and metal chelate crosslinking agents are suitable. Isocyanate crosslinking agents are preferred as they suitably balance flexural recovery and flexural retention. One crosslinking agent may be used alone or in combination of two or more.

[0159] As isocyanate-based crosslinking agents, polyfunctional isocyanates (compounds having an average of two or more isocyanate groups per molecule, including compounds with isocyanurate structures) are preferred. Isocyanate-based crosslinking agents can be used alone or in combination of two or more.

[0160] Examples of polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

[0161] 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; 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and lysine diisocyanate.

[0162] Specific examples of alicyclic 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 phenyl dimethyl diisocyanate, hydrogenated toluene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0163] Specific examples of aromatic polyisocyanates include: 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, and 2,2'-diphenylpropane-4,4'-diisocyanate. Cyanates, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, terephthalene diisocyanate, naphthyl-1,4-diisocyanate, naphthyl-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, phenylenedimethyl-1,4-diisocyanate, phenylenedimethyl-1,3-diisocyanate, etc.

[0164] Preferred polyfunctional isocyanates include those having an average of three or more isocyanate groups per molecule. These isocyanates with three or more functions can be polymers (e.g., dimers or trimers) of difunctional or trifunctional isocyanates, derivatives (e.g., addition reaction products of polyols with two or more molecules of polyfunctional isocyanates), polymers, etc. Examples include: dimers and trimers of diphenylmethane diisocyanate, isocyanurates of hexamethylene diisocyanate (trimeric adducts of isocyanurate structures), reaction products of trimethylolpropane and toluene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, trimethylolpropane adduct of phenyl diisocyanate, trimethylolpropane adduct of isophorone diisocyanate, trimethylolpropane adduct of hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate, polyester polyisocyanate, and these adducts with various polyols, as well as polyisocyanates that have been multifunctionalized using isocyanurate bonds, biuret bonds, urethane bonds, etc.

[0165] Commercially available examples of the aforementioned polyfunctional isocyanates include: "Duranate TPA-100" manufactured by Asahi Kasei Chemicals; "Coronate L", "Coronate HL", "Coronate HK", "Coronate HX", and "Coronate 2096" manufactured by Tosoh Chemicals; and "Takenate D110N", "Takenate D120N", "Takenate D140N", and "Takenate D160N" manufactured by Mitsui Chemicals.

[0166] Examples of epoxy crosslinking agents include: bisphenol A, epichlorohydrin-type epoxy resins, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidylamine, N,N,N',N'-tetraglycidyl-m-phenylenediamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, etc. These can be used alone or in combination of two or more.

[0167] Regarding metal chelate compounds, examples of metal components include aluminum, iron, tin, titanium, and nickel, while examples of chelate components include acetylene, methyl acetoacetate, and ethyl lactate. These can be used alone or in combination of two or more.

[0168] When using a crosslinking agent, the amount used is not particularly limited; for example, it can be more than 0 parts by weight relative to 100 parts by weight of polymer (A). Furthermore, relative to 100 parts by weight of polymer (A), the amount of crosslinking agent used can be, for example, 0.01 parts by weight or more, preferably 0.05 parts by weight or more. By increasing the amount of crosslinking agent used, the initial adhesion force is suppressed, and there is a tendency to improve reprocessability. There is a tendency for excellent flexural recovery and processability. In some embodiments, relative to 100 parts by weight of polymer (A), the amount of crosslinking agent used can be 0.1 parts by weight or more, 0.5 parts by weight or more, or 0.8 parts by weight or more. On the other hand, from the viewpoint of obtaining an increase in adhesion force after heating while appropriately allowing for the mobility of polymer (B), relative to 100 parts by weight of polymer (A), the amount of crosslinking agent used is generally suitable to be 15 parts by weight or less, and can be 10 parts by weight or less, or 5 parts by weight or less.

[0169] The technology disclosed herein is preferably implemented by using at least an isocyanate-based crosslinking agent as the crosslinking agent. From the viewpoint of balancing good reprocessability in the initial application stage with increased adhesion after heating, in some embodiments, the amount of isocyanate-based crosslinking agent used relative to 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 can be 0.10 parts by weight or more, or 0.15 parts by weight or more (e.g., 0.20 parts by weight or more). By increasing the amount of isocyanate-based crosslinking agent used, suitable cohesive strength and elastic modulus can be obtained, with a tendency for excellent flexural recovery and processability. Furthermore, relative to 100 parts by weight of polymer (A), the amount of isocyanate-based crosslinking agent used 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, further preferably less than 0.3 parts by weight, and particularly preferably less than 0.2 parts by weight (e.g., 0.15 parts by weight or less). As a result, the cohesive force of the adhesive, and consequently its elastic modulus (typically the surface elastic modulus), is moderately reduced, resulting in good flexural holding force and also making it easier to achieve an increase in adhesive force after heating.

[0170] When an isocyanate-based crosslinking agent is used in an adhesive layer containing hydroxyl-containing monomers as monomer units, the molar ratio of isocyanate groups to hydroxyl groups in the adhesive layer ([NCO] / [OH]) can be set to, for example, 0.001 or more, without particular limitation. By increasing the amount of isocyanate-based crosslinking agent used relative to the hydroxyl-containing monomers in this way, the elastic modulus (typically the surface elastic modulus) of the adhesive becomes a suitable range, tending to improve flexural resilience. Furthermore, it tends to have excellent processability. In some preferred embodiments, the above molar ratio ([NCO] / [OH]) is 0.002 or more, more preferably 0.004 or more, even more preferably 0.006 or more (e.g., 0.007 or more), and can be 0.010 or more, 0.020 or more, or 0.030 or more. Furthermore, the above molar ratio ([NCO] / [OH]) can be set to, for example, 1.0 or less, or 0.10 or less. By limiting the above molar ratio to a specified value or below, a crosslinked structure suitable for significantly increasing the adhesive strength after heating relative to the initial adhesive strength 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 also be 0.005 or less. It should be noted that in the adhesive layer, the isocyanate groups and hydroxyl groups may exist in a state where at least a portion of them are chemically bonded (crosslinked). More specifically, the above isocyanate groups may exist in a state where they are chemically bonded (crosslinked) to the above hydroxyl groups. On the other hand, the above hydroxyl groups may exist in a state where a portion of them are chemically bonded to the isocyanate groups and another portion is not chemically bonded (crosslinked) to the above isocyanate groups.

[0171] In some preferred embodiments, the adhesive layer contains a catalyst. The catalyst can be added to promote the curing of the adhesive layer during its formation, typically to make any of the aforementioned crosslinking reactions more efficient. Therefore, the catalyst is also called a curing catalyst or a crosslinking catalyst. By adding a catalyst, initial curing can be promoted, and side reactions that cause bubbles to form on the surface of the adhesive layer can be suppressed. Examples of catalysts include: iron-based catalysts, tin-based catalysts, titanium-based catalysts, zirconium-based catalysts, lead-based catalysts, cobalt-based catalysts, zinc-based catalysts, organometallic compounds, tertiary amine compounds, etc. These can be used alone or in combination of two or more. From the perspective of balancing reaction rate and pot life, iron-based catalysts and tin-based catalysts are preferred, with iron-based catalysts being particularly preferred.

[0172] Examples of iron-based catalysts include iron acetylacetone and iron 2-ethylhexanoate. Iron-based catalysts can be used alone or in combination of two or more.

[0173] Examples of tin-based catalysts include: dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin maleate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, tributyltin methanol, tributyltin acetate, triethyltin ethanol, tributyltin ethanol, dioctyltin oxide, dioctyltin dilaurate, tributyltin chloride, trichlorotin tributylacetate, and tin 2-ethylhexanoate. Tin-based catalysts can be used alone or in combination of two or more.

[0174] The amount of catalyst used is not particularly limited, but relative to 100 parts by weight of polymer (A), it can be, for example, 0.0001 parts by weight or more, preferably 0.001 parts by weight or more, more preferably 0.003 parts by weight or more, further 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 in the self-adhesive layer can be suppressed, and a smooth adhesive surface can be easily obtained. Furthermore, relative to 100 parts by weight of polymer (A), the amount of catalyst used can be, for example, 1 part by weight or less, or even 0.1 parts by weight or less. In some preferred embodiments, relative to 100 parts by weight of polymer (A), the amount of catalyst used is 0.03 parts by weight or less, more preferably 0.02 parts by weight or less, further preferably 0.01 parts by weight or less, or even 0.005 parts by weight or less. By appropriately limiting the content of catalyst relative to 100 parts by weight of polymer (A), a suitable increase in adhesive strength can be easily achieved.

[0175] When a catalyst is used in a composition where the adhesive layer contains hydroxyl-containing monomers as monomer units, the amount of catalyst used can be set as the molar ratio of the catalyst to the hydroxyl groups in the adhesive layer ([catalyst] / [OH]) is, for example, 1.0 × 10⁻⁶. -6 The above amount is preferably 1.0 × 10 -5 The above, more preferably 1.0×10 -4 The above is further preferred to be 2.0×10 -4 The above is particularly preferred, with 3.0×10⁻⁶ being the optimal value. -4 The amounts mentioned above are not specifically limited. By using an appropriate amount of catalyst, the generation of bubbles in the self-adhesive layer can be suppressed, making it easy to obtain a smooth adhesive surface. Furthermore, the above molar ratio ([catalyst] / [OH]) can be set, for example, to 5.0 × 10⁻⁶. -2 The following can also be 5.0×10 -3 Below. In some preferred embodiments, the above molar ratio ([catalyst] / [OH]) is 3.0 × 10⁻⁶. -3 Hereinafter, 1.0 × 10 is more preferred. -3 The following is a further preferred value: 5.0 × 10 -4 The following can also be 3.0×10 -4The following applies. By appropriately limiting the catalyst content, a suitable increase in adhesion can be easily achieved.

[0176] (Tackifying resin)

[0177] The adhesive layer may contain a tackifying resin as needed. There are no particular limitations on the tackifying resin; examples include rosin-based tackifying resins, terpene-based tackifying resins, phenol-based tackifying resins, hydrocarbon-based tackifying resins, ketone-based tackifying resins, polyamide-based tackifying resins, epoxy-based tackifying resins, and elastic system tackifying resins. One tackifying resin may be used alone or in combination of two or more.

[0178] The content of the tackifying resin is not particularly limited and can be set according to the purpose and application to achieve appropriate adhesive properties. The content of the tackifying resin (the total amount of two or more tackifying resins) relative to 100 parts by weight of polymer (A) can be set, for example, to about 5 to 500 parts by weight. Furthermore, the technology disclosed herein can preferably be implemented by limiting the amount of tackifying resin used. For example, the content of the tackifying resin relative to 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 parts by weight to less than 1 part by weight). In some embodiments, the adhesive layer substantially does not contain tackifying resin.

[0179] Furthermore, the adhesive layer in the technology disclosed herein may contain, as needed, known additives that can be used in adhesives, such as leveling agents, plasticizers, softeners, colorants (dyes, pigments, etc.), fillers, antistatic agents, anti-aging agents, ultraviolet absorbers, antioxidants, light stabilizers, and preservatives, to a extent that does not significantly impair the effects of the present invention.

[0180] The adhesive layer constituting the reinforcing film disclosed herein can be a cured layer of the adhesive composition. That is, this adhesive layer can be formed by applying (e.g., coating) a water-dispersible, solvent-based, photocurable, or hot-melt adhesive composition to a suitable surface followed by a curing process. When two or more curing processes (drying, crosslinking, polymerization, cooling, etc.) are performed, these can be carried out simultaneously or in multiple stages. For adhesive compositions using a partial polymer (polymer slurry) of monomeric raw materials, a final copolymerization reaction is typically performed as the aforementioned curing process. That is, a portion of the 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. Crosslinking, drying, or other curing processes can be performed as needed. For example, in the case of a photocurable adhesive composition requiring drying, photocuring after drying is preferable. For adhesive compositions using a complete polymer, drying (heat drying), crosslinking, or other processes are typically performed as the aforementioned curing processes as needed.

[0181] The coating of the adhesive composition can be carried out using commonly used coating machines such as gravure roller coaters, reverse roller coaters, licker coaters, dip roller coaters, bar coaters, doctor blade coaters, and spray coaters.

[0182] The thickness of the adhesive layer is not particularly limited, but can be set to 6 μm or more. In some embodiments, the thickness of the adhesive layer can be 8 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, or even more than 20 μm. Increasing the thickness of the adhesive layer tends to increase the adhesive strength after heating. Furthermore, in some embodiments, the thickness of the adhesive layer can 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 even 40 μm or less. Not having an excessively thick adhesive layer is advantageous from the viewpoints of thinning the reinforcing film and preventing cohesive failure of the adhesive layer. A reinforcing film having an adhesive layer within the above-mentioned thickness range can achieve a balance between adhesive properties such as adhesive strength, flexural resilience, and flexural holding force. It should be noted that when a reinforcing film having a first adhesive layer and a second adhesive layer is provided on both the first and second sides of the substrate, the thickness of the adhesive layer can be at least the thickness of the first adhesive layer. The thickness of the second adhesive layer can also be selected from the same range. Furthermore, in the case of a reinforcing film without a substrate, the thickness of the reinforcing film is the same as the thickness of the adhesive layer.

[0183] <Supporting substrate>

[0184] Some reinforcing films can be in the form of adhesive sheets with adhesive layers on one or both sides of a supporting substrate. The material of the supporting substrate is not particularly limited and can be appropriately selected according to the intended use and application method of the reinforcing film. Non-limiting examples of usable substrates include: resin films such as plastic films; foam sheets formed from foams such as polyurethane foam, polyethylene foam, and polychloroprene foam; woven and non-woven fabrics obtained alone or through blending of various fibrous materials (such as natural fibers like hemp and cotton, synthetic fibers like polyester and vinylon, and semi-synthetic fibers like acetate); paper types such as Japanese paper, high-quality paper, kraft paper, and crepe paper; metal foils such as aluminum foil and copper foil; etc. Substrates for structures formed by combining these materials can also be used. Examples of such composite substrates include substrates with structures formed by laminating metal foil with the aforementioned plastic films, and plastic substrates reinforced with inorganic fibers such as glass cloth.

[0185] As the substrate for the reinforcing film disclosed herein, various film substrates are preferably used. These film substrates can be porous substrates, such as foamed films or nonwoven sheets, or non-porous substrates, or substrates with a structure consisting of porous and non-porous layers stacked together. In some embodiments, as the aforementioned film substrate, a film substrate comprising a base film of a resin film that can independently maintain its shape (self-supporting or independent) is preferably used. Here, "resin film" refers to a non-porous structure, typically a substantially bubble-free (pore-free) resin film. Therefore, the aforementioned resin film is a concept distinct from foamed films and nonwoven fabrics. As the aforementioned resin film, a resin film that can independently maintain its shape (self-supporting or independent) is preferably used. The aforementioned resin film can be a single-layer structure or a multi-layer structure with two or more layers (e.g., a three-layer structure).

[0186] For example, resin materials constituting the resin film can be polyester, polyolefin, nylon 6, nylon 66, polyamide (PA) such as partially aromatic polyamides, polyimide (PI), polyamide-imide (PAI), polyetheretherketone (PEEK), polyethersulfone (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), ethylene-vinyl acetate copolymer (EVA), polytetrafluoroethylene (PTFE) and other fluoropolymers, acrylic resins, polyacrylates, polystyrene, polyvinyl chloride, polyvinylidene chloride and other resins. The resin film can be a resin film formed using a resin material containing only one such resin, or a resin film formed using a mixture of two or more resin materials. The resin film can be unstretched or stretched (e.g., uniaxially or biaxially stretched).

[0187] Suitable examples of resin materials constituting resin films include polyimide resins, polyester resins, PPS resins, and polyolefin resins. Here, polyimide resins refer to resins containing polyimide in a proportion exceeding 50% by weight. Similarly, polyester resins refer to resins containing polyester in a proportion exceeding 50% by weight, PPS resins refer to resins containing PPS in a proportion exceeding 50% by weight, and polyolefin resins refer to resins containing polyolefins in a proportion exceeding 50% by weight.

[0188] Specific examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate.

[0189] As a polyolefin resin, a single polyolefin can be used, or two or more polyolefins can be used in combination. This polyolefin can be, for example, a homopolymer of α-olefin, a copolymer of two or more α-olefins, or a copolymer of one or more α-olefins with other vinyl monomers. Specific examples include polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene rubber (EPR), ethylene-propylene-butene copolymers, ethylene-butene copolymers, ethylene-vinyl alcohol copolymers, and ethylene-ethyl acrylate copolymers. Either low-density (LD) polyolefins or high-density (HD) polyolefins can be used. Examples of polyolefin resin films include unstretched polypropylene (CPP) film, biaxially oriented polypropylene (OPP) film, low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, medium-density polyethylene (MDPE) film, high-density polyethylene (HDPE) film, polyethylene (PE) film made by blending two or more types of polyethylene (PE), and PP / PE blend film made by blending polypropylene (PP) and polyethylene (PE).

[0190] Specific examples of resin films that can be preferably used as the base film for the reinforcing films disclosed herein include PI films, PET films, PEN films, PPS films, PEEK films, CPP films, and OPP films.

[0191] In the resin film, known additives such as light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, lubricants, and antiblocking agents can be added as needed, without significantly impairing the effects of the present invention. The amount of additives added is not particularly limited and can be appropriately set according to the intended purpose.

[0192] There are no particular limitations on the manufacturing method of resin films. For example, conventional resin film forming methods known in the past, such as extrusion molding, blow molding, T-die casting, and calendering, can be appropriately used.

[0193] The aforementioned substrate may be a substrate substantially composed of such a base film. Alternatively, the aforementioned substrate may also be a substrate that includes auxiliary layers in addition to the aforementioned base film. Examples of such auxiliary layers include optical property adjustment layers (e.g., coloring layers, anti-reflective layers), printing layers for imparting a desired appearance to the substrate, laminated layers, antistatic layers, primer layers, release layers, and other surface treatment layers.

[0194] The thickness of the substrate is not particularly limited and can be selected according to the intended use or application method of the reinforcing film. For example, the substrate thickness can be 1000 μm or less. In some cases, from the viewpoint of the processability and workability of the reinforcing film, the substrate thickness can be, for example, 500 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less. From the viewpoint of miniaturization and weight reduction of products using the reinforcing film, in some cases, the substrate thickness can 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. If the substrate thickness is reduced, the flexibility of the reinforcing film and its adaptability to the surface shape of the adhered object tend to improve. Furthermore, from the viewpoint of processability and workability, the thickness of the substrate can be, for example, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, or 25 μm or more. In some embodiments, the thickness of the substrate can 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 reinforcing films, a substrate with a thickness of 30 μm or more is preferably used.

[0195] Conventionally known surface treatments, such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and the formation of a base coat based on a primer, can be applied to the first surface of the substrate as needed. Such surface treatments can be used to improve the anchoring strength of the adhesive layer to the substrate. For example, in reinforcing films having a substrate comprising a resin film as a base film, a substrate subjected to the aforementioned anchoring strength improvement treatment is preferred. The above surface treatments can be applied individually or in combination. The composition of the primer used in the formation of the base coat is not particularly limited, and can be suitably selected from known primers. The thickness of the base coat is not particularly limited, but is generally suitable at around 0.01 μm to 1 μm, preferably around 0.1 μm to 1 μm. Other treatments that can be applied to the first surface of the substrate as needed include antistatic layer formation treatment, coloring layer formation treatment, and printing treatment.

[0196] When the reinforcing film disclosed here is in the form of a single-sided adhesive sheet with an adhesive layer only on the first side of the substrate, conventional surface treatments such as peeling treatment and antistatic treatment can be applied to the second side of the substrate as needed. For example, by surface treating the back side of the substrate with a peeling agent (typically by providing a peeling layer based on the peeling agent), the unwinding force of the reinforcing film wound into a roll can be reduced. As peeling agents, silicone-based peeling agents, long-chain alkyl-based peeling agents, olefin-based peeling agents, fluorinated peeling agents, fatty acid amide-based peeling agents, molybdenum sulfide, silica powder, etc., can be used. In addition, for purposes such as improving printability, reducing light reflectivity, and improving re-adhesion, the second side of the substrate can be treated with corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, etc. In the case of a double-sided adhesive sheet, the second side of the substrate can be treated with the same surface treatment as the surface treatments exemplified above that can be applied to the first side of the substrate, as needed. It should be noted that the surface treatment applied to the first side of the substrate and the surface treatment applied to the second side can be the same or different.

[0197] <Enhancing the properties of thin films>

[0198] The reinforcing film disclosed herein preferably measures the initial adhesion strength N after being bonded to a stainless steel sheet and held at 23°C for 30 minutes. 23 Limited to below a specified value. In some methods, the adhesive force N 23 For example, less than 500gf / 25mm is preferred, less than 400gf / 25mm is more preferred, less than 300gf / 25mm is even more preferred, and less than 250gf / 25mm (e.g., less than 200gf / 25mm) is particularly preferred, and less than 150gf / 25mm is also acceptable. Adhesive strength N 23 Low adhesion is preferred from a reprocessability point of view. 23 There is no specific lower limit, for example, it can be above 1gf / 25mm. From the perspective of workability for the adhered object and preventing positional shift before the adhesive force increases, the adhesive force N... 23 Typically, a strength of 10gf / 25mm or higher is suitable. From the perspective of improving adhesion after heating, in some methods, the adhesion force N... 23 For example, it can be 20gf / 25mm or higher, 50gf / 25mm or higher, 80gf / 25mm or higher, or 100gf / 25mm or higher (e.g., 150gf / 25mm or higher).

[0199] Adhesive force N 23[gf / 25mm] is determined as follows: After pressing the adhesive onto a stainless steel (SUS) sheet used as the substrate and placing it at 23°C and 50% RH for 30 minutes, the 180° peel adhesion force is measured under the same conditions (i.e., 23°C), at a peel angle of 180° and a tensile speed of 300 mm / min. SUS304BA sheet is used as the substrate. During the test, a suitable backing material (e.g., a PET film approximately 25 μm thick) can be attached to the reinforcing film of the test object for reinforcement as needed. Adhesion force N 23 More specifically, the initial adhesion force can be measured based on the method for measuring the initial adhesion force described in the following examples.

[0200] The reinforcing film disclosed herein is a film whose adhesive strength increases upon heating, for example, an adhesive strength N. 60 This refers to a film with an adhesion strength exceeding 300 gf / 25 mm, measured at 23°C after being bonded to a stainless steel sheet and held at 60°C for 60 minutes. In some methods, the adhesion strength N... 60 The adhesive strength is 400 gf / 25 mm or higher, and preferably 500 gf / 25 mm or higher. The reinforcing film meeting these characteristics, after being applied to the substrate, exhibits an adhesive strength that increases to a specified value or higher upon heating. According to the technology disclosed herein, strong adhesive strength can be obtained through heating. In some preferred embodiments, the adhesive strength N... 60 The strength is 600gf / 25mm or higher, more preferably 700gf / 25mm or higher, and can be 800gf / 25mm or higher, or 900gf / 25mm or higher. Adhesive strength (N) 60 There is no specific upper limit. From the viewpoint of enhancing the ease of manufacturing and economy of thin films, in some methods, the adhesive force N... 60 For example, it can be below 3000gf / 25mm, below 1500gf / 25mm, or below 1000gf / 25mm.

[0201] Adhesive force N 60 [gf / 25mm] is determined as follows: The substrate is pressed onto an SUS board and held at 60°C for 60 minutes, followed by placement at 23°C and 50% RH for 30 minutes. Then, under the same conditions, the 180° peel adhesion is measured at a peel angle of 180° and a tensile speed of 300 mm / min. As the substrate, the adhesion force N... 23 Similarly, SUS304BA plates are used. During measurement, appropriate backing material (e.g., a PET film approximately 25 μm thick) can be attached to the reinforcing film of the test object for reinforcement as needed. Adhesion force N 60 More specifically, the determination can be performed based on the method for measuring adhesive strength after heating as described in the following examples.

[0202] Adhesive force N 60 [gf / 25mm] relative to adhesion strength N 23 The ratio of [gf / 25mm], i.e., the increase in adhesive strength N 60 / N 23 Without specific limitations, in some methods, N 60 / N 23 The value is preferably 1.5 or higher, more preferably 2.0 or higher, even more preferably 2.5 or higher, and still more preferably 3.0 or higher (e.g., 3.5 or higher), and may also exceed 5.0 (e.g., exceeding 7.0). Using N 60 / N 23 Large reinforcing films exhibit good reprocessability in the initial application stage, and subsequent heating can significantly increase adhesive strength. 60 / N 23 There is no specific upper limit for N, which is usually below 100. From the perspective of ease of manufacturing and economy of reinforcing films, it can be below 30, below 15, or below 10. In some methods, N... 60 / N 23 For example, it can be 5 or less, 3 or less, or 2 or less.

[0203] It should be noted that the adhesive strength of the reinforcing film after heating disclosed herein represents a characteristic of the reinforcing film and does not limit its application. In other words, the application of the reinforcing film disclosed herein is not limited to heating at 60°C for 60 minutes; for example, it can also be used without specifically heating to room temperature (typically 20°C to 30°C, and typically 23°C to 25°C). In this application method, the adhesive strength increases over a longer period, achieving a strong bond. Furthermore, the reinforcing film disclosed herein can have its adhesive strength increased by heating at temperatures exceeding 30°C (e.g., around 50 to 70°C) or above 60°C at any time after application. The heating temperature in this heating treatment is not particularly limited and can be set considering workability, economy, the substrate of the reinforcing film, and the heat resistance of the adhered objects. The aforementioned heating temperature may be, for example, less than 150°C, less than 120°C, less than 100°C, less than 80°C, or less than 70°C. Furthermore, the aforementioned heating temperature can be set to, for example, 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, 80°C or higher, or 100°C or higher. The heating time is not particularly limited; for example, it can be less than 3 hours, less than 1 hour, less than 30 minutes, or less than 10 minutes. Alternatively, the heating time can be, for example, more than 1 minute, more than 15 minutes, more than 30 minutes, or more than 1 hour. Or, a longer heating treatment can be performed within the limit that the reinforcing film or the adhered material does not experience significant thermal degradation. It should be noted that the heating treatment can be performed in one go or in multiple stages.

[0204] <Reinforcing Film with Substrate>

[0205] When the reinforcing film disclosed herein is in the form of an adhesive sheet with a substrate, the thickness of the reinforcing film can be, for example, 1000 μm or less, 600 μm or less, 350 μm or less, or 250 μm or less. From the viewpoint of miniaturization, weight reduction, and thinning of products using the reinforcing film, in some embodiments, the thickness of the reinforcing film can be, for example, 200 μm or less, 175 μm or less, 140 μm or less, 120 μm or less, or 100 μm or less (e.g., less than 100 μm). Furthermore, from the viewpoint of operability, the thickness of the reinforcing film can 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 methods, the thickness of the reinforcing film can be, for example, 50 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, or 120 μm or more. There is no particular upper limit to the thickness of the reinforcing film.

[0206] It should be noted that the thickness of the reinforcing film refers to the thickness of the portion adhered to the object being bonded. For example, in... Figure 1 In the reinforcing film 1 shown, the thickness refers to the thickness from the adhesive surface 21A of the reinforcing film 1 to the second surface 10B of the substrate 10, excluding the thickness of the release liner 31.

[0207] The reinforcing film disclosed herein is preferably implemented such that the thickness Ts of the supporting substrate is greater than the thickness Ta of the adhesive layer, i.e., Ts / Ta is greater than 1. Ts / Ta can be, for example, 1.1 or more, 1.2 or more, 1.5 or more, or 1.7 or more, without particular limitation. For example, by increasing Ts / Ta, there is a tendency to achieve good results even when the reinforcing film is made thin. In some embodiments, Ts / Ta can be 2 or more (e.g., greater than 2), 2.5 or more, or 2.8 or more. Furthermore, Ts / Ta can be, for example, 50 or less, or 20 or less. From the viewpoint that high post-heat adhesion is easily achieved even when the reinforcing film is made thin, Ts / Ta can be, for example, 10 or less, 8 or less, or 5 or less.

[0208] The adhesive layer described above is preferably fixed to the supporting substrate. Here, "fixed" means that in a reinforcing film where the adhesive force increases after being applied to the adherend, the adhesive layer exhibits sufficient anchoring to the supporting substrate to the extent that the interface between the adhesive layer and the supporting substrate does not peel off when the reinforcing film is peeled off from the adherend. By fixing the adhesive layer to the supporting substrate of the reinforcing film with a substrate, the adherend and the supporting substrate can be firmly integrated. As a preferred example of a reinforcing film with the adhesive layer fixed to the substrate, a reinforcing film in which peeling (anchoring failure) does not occur between the adhesive layer and the supporting substrate when the adhesive force after heating is measured is given. A reinforcing film in which anchoring failure does not occur when the adhesive force after heating is measured is a preferred example of a reinforcing film with the adhesive layer fixed to the substrate.

[0209] The reinforcing film disclosed herein can preferably be manufactured, for example, by a method comprising the following steps: 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 be accompanied by one or more of the following: drying, crosslinking, polymerization, cooling, etc. Compared to a method of depositing the adhesive layer on the first surface of the substrate by curing the liquid adhesive composition on the first surface of the substrate, this method improves the anchoring strength of the adhesive layer to the substrate. Using this method, a reinforcing film in which the adhesive layer is fixed to the substrate can be suitably manufactured.

[0210] In some methods, as a way to bring the liquid adhesive composition into contact with the first surface of the substrate, the adhesive composition can be directly applied to the first surface of the substrate. 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 adhered to the first surface of the substrate and the first surface of the adhesive layer is in contact with the release surface. The release surface can be the surface of the release liner, the back surface of the substrate that has undergone the release treatment, etc.

[0211] Alternatively, for example, in the case of a photocurable adhesive composition using a portion of a polymer (polymer slurry) of monomer raw materials, the adhesive composition can be applied to the release surface, and then the first surface of the substrate can be covered on the applied adhesive composition, thereby bringing the uncured adhesive composition into contact with the first surface of the substrate. In this state, the adhesive composition sandwiched between the first surface of the substrate and the release surface is irradiated with light to cure it, thereby forming an adhesive layer.

[0212] It should be noted that the methods illustrated above are not limited to the manufacturing method of the reinforcing film disclosed herein. When manufacturing the reinforcing film disclosed herein, one or more suitable methods for adhering the adhesive layer to the first surface of the substrate can be used alone or in combination. Examples of such methods include: a method for curing a liquid adhesive composition on the first surface of the substrate to form an adhesive layer as described above; and a method for performing a surface treatment on the first surface of the substrate to improve the anchoring properties of the adhesive layer. For example, if the anchoring properties of the adhesive layer to the substrate can be sufficiently improved by providing a primer coating or similar method on the first surface of the substrate, the reinforcing film can be manufactured by adhering the cured adhesive layer to the first surface of the substrate. Furthermore, the anchoring properties of the adhesive layer to the substrate can also be improved by selecting the material of the substrate and the composition of the adhesive. Additionally, the anchoring properties of the adhesive layer to the substrate can be improved by applying a temperature higher than room temperature to the reinforcing film having an adhesive layer on the first surface of the substrate. The temperature applied to improve anchoring properties can be, for example, around 35°C to 80°C, around 40°C to 70°C, or around 45°C to 60°C.

[0213] When the reinforcing film disclosed herein is in the form of an adhesive sheet (i.e., a double-sided adhesive sheet with a substrate) having a first adhesive layer disposed on a first side of a substrate and a second adhesive layer disposed on a second side of the substrate, the first adhesive layer and the second adhesive layer may have the same or different compositions. If the compositions of the first adhesive layer and the second adhesive layer are different, the differences may be, for example, differences in composition, structure (thickness, surface roughness, forming range, forming pattern, etc.). For example, the second adhesive layer may be an adhesive layer that does not contain polymer B. Furthermore, the surface elastic modulus of the surface of the second adhesive layer (the second adhesive surface) at 23°C may be outside the range of 1 to 20 kPa (e.g., exceeding 20 kPa) or may be 30 kPa or more.

[0214] <Reinforcing film with release liner>

[0215] The reinforcing film disclosed herein can be in the form of an adhesive product in which the surface (adhesive surface) of the adhesive layer abuts against the release surface of the release liner. Therefore, according to this specification, an adhesive sheet with a release liner can be provided, comprising any reinforcing film disclosed herein and a release liner having a release surface abutting against the adhesive surface of the reinforcing film.

[0216] The thickness of the release liner is not particularly limited, but is generally suitable at around 5 μm to 200 μm. If the thickness of the release liner is within this range, the adhesion operation to the adhesive layer and the peeling operation of the self-adhesive layer are excellent, and therefore preferred. 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. Furthermore, from the viewpoint of facilitating the peeling of the self-adhesive layer, the thickness of the release liner may be, for example, 100 μm or less, or 80 μm or less. As needed, the release liner can be subjected to known antistatic treatments such as coating, compounding, or vapor deposition.

[0217] The release liner is not particularly limited. For example, release liners with a release layer on the surface of the liner substrate, such as resin film or paper (which may be paper laminated with resins such as polyethylene), or release liners containing resin films made of low-adhesion materials such as fluoropolymers (polytetrafluoroethylene, etc.) or polyolefin resins (polyethylene, polypropylene, etc.) can be used. From the perspective of excellent surface smoothness, release liners with a release layer on the surface of the resin film used as the liner substrate, or release liners containing resin films made of low-adhesion materials, are preferred. As for the resin film, there is no particular limitation as long as it is a film that can protect the adhesive layer. 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. The formation of the aforementioned release layer can utilize known release agents such as silicone-based release agents, long-chain alkyl-based release agents, olefin-based release agents, fluorinated release agents, fatty acid amide-based release agents, molybdenum sulfide, and silica powder. Silicone-based release agents are particularly preferred.

[0218] There are no particular limitations on the thickness of the release layer, but a thickness of approximately 0.01 μm to 1 μm is generally suitable, preferably approximately 0.1 μm to 1 μm. There are no particular limitations on the method for forming the release layer; any known method can be used depending on the type of release agent employed.

[0219] <Uses>

[0220] The reinforcing film provided in this specification exhibits good reprocessability in the initial stage of application to the substrate, thus helping to suppress yield reduction and improve the quality of products containing the reinforcing film. Furthermore, the adhesive strength of the reinforcing film can be significantly increased by curing or heating after application to the substrate. For example, by heating at an appropriate time after application to the substrate, the reinforcing film can be firmly bonded to the substrate. Utilizing these features, the reinforcing film disclosed herein is preferably used in various fields for reinforcing components in various products.

[0221] The reinforcing film disclosed herein can preferably be used as a substrate-bound adhesive sheet, for example, in the form of an adhesive layer provided on at least the first side of a film-like substrate having a first side and a second side, and is applied to an adherend to reinforce the adherend. In this reinforcing film, a film substrate comprising a resin film as a base film is preferably used as the film substrate. Furthermore, from the viewpoint of improving reinforcing performance, the adhesive layer is preferably adhered to the first side of the film-like substrate.

[0222] For example, optical components used in optical products and electronic components used in electronic products are becoming increasingly integrated, miniaturized, lightweight, and thinner, potentially involving the stacking of multiple thin optical / electronic components with different coefficients of linear expansion and thicknesses. By attaching the reinforcing film described above to such components, appropriate rigidity can be imparted to them. Consequently, the manufacturing process and / or the manufactured product can suppress curling and bending caused by stress that may arise between multiple components with different coefficients of linear expansion and thicknesses.

[0223] Furthermore, in the manufacturing processes of optical / electronic products, when cutting or shaping thin optical / electronic components as described above, attaching a reinforcing film to the component can mitigate localized stress concentrations during processing, reducing the risk of cracks, breakage, and peeling of laminated components. Attaching reinforcing components to optical / electronic components can also help alleviate localized stress concentrations during transport, stacking, and rotation, and suppress bending and flexing caused by the component's own weight.

[0224] Furthermore, when optical products, electronic products, and other devices incorporating the aforementioned reinforcing film are used by consumers in the market, the pressure exerted on the device can be mitigated by including the reinforcing film in situations such as unintentional stress such as the device being dropped, placed under heavy objects, or impacted by flying objects. Therefore, by including the reinforcing film in the aforementioned device, the durability of the device can be improved.

[0225] Furthermore, the reinforcing film disclosed herein can preferably be used by attaching it to components constituting various portable equipment. The term "portable" here is insufficient to simply mean "carryable," but rather refers to portability at a level that allows a standard adult to handle it relatively easily. Examples of portable equipment include mobile phones, smartphones, tablet PCs, laptop PCs, various wearable devices, digital cameras, digital camcorders, audio equipment (portable music players, IC recorders, etc.), calculators (desktop calculators), portable gaming devices, electronic dictionaries, electronic notebooks, e-books, in-vehicle information devices, portable radios, portable televisions, portable printers, portable scanners, portable modems, and other portable electronic devices, as well as mechanical wristwatches, pocket watches, flashlights, hand mirrors, etc. Examples of components constituting the aforementioned portable electronic devices can include optical films and display panels used in image display devices such as liquid crystal displays and thin-film displays. The reinforcing film disclosed herein can also preferably be used by attaching it to various components in automobiles, home appliances, etc.

[0226] Furthermore, the reinforcing film disclosed herein possesses bend recovery and bend retention properties, thus it is preferably used to attach to components of devices that have bendable elements (e.g., flexible devices such as flexible displays; also referred to as rollable or foldable devices). Examples of such devices include the various portable devices described above. Examples of components constituting such portable electronic devices include optical films and display panels for image display devices such as liquid crystal displays and organic EL (electroluminescent) displays. The reinforcing film disclosed herein is preferably used in such portable electronic devices for reinforcing components constituting the device (typically image display devices referred to as flexible or foldable devices).

[0227] Furthermore, the reinforcing film disclosed herein is suitable for reinforcing optical components used as components of liquid crystal display panels, plasma display panels (PDPs), organic EL displays, etc., during manufacturing and transportation. It is useful as a reinforcing film for optical components such as polarizing plates (polarizing films), wavelength plates, retardation plates, optical compensation films, brightness enhancement films, light diffusers, and reflectors used in liquid crystal display panels.

[0228] It should be noted that the uses of the reinforcing film disclosed herein are not particularly limited, and it can be used for various applications aimed at imparting rigidity, impact resistance, etc. The reinforcing film disclosed herein is not only preferably used in flexible equipment applications as described above, but can also be used in other applications excluding flexible equipment. The fact that the reinforcing film has flexural recovery and flexural holding force means that its applicability is less restricted, which is a significant advantage in practical applications.

[0229] Example

[0230] The following describes several embodiments related to the present invention, but it is not intended to limit the invention to the specific examples shown. It should be noted that, unless otherwise specified, "parts" and "%" in the following description refer to weight.

[0231] [Synthesis of Polymer (A)]

[0232] (Synthesis example A1)

[0233] In a four-necked flask equipped with a stirring blade, thermometer, nitrogen inlet tube, and 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 slowly, and the liquid temperature in the flask was maintained at approximately 65°C for 6 hours to prepare an acrylic polymer A1 solution with a polymer concentration of 35%. The weight-average molecular weight (Mw) of acrylic polymer A1 was 540,000.

[0234] (Synthesis Example A2)

[0235] Except for changing the monomer composition to 2EHA / 4HBA / ACMO / n-butyl acrylate (BA) = 86.1 parts / 9.7 parts / 1.8 parts / 2.4 parts, solution polymerization was carried out in the same manner as in synthesis example A1, thereby obtaining a solution of acrylic polymer A2.

[0236] (Synthesis Example A3)

[0237] Except for changing the monomer composition to BA / 4HBA = 96 parts / 4 parts, solution polymerization was carried out in the same manner as in synthesis example A1, thereby obtaining a solution of acrylic polymer A3.

[0238] (Synthesis Example A4)

[0239] Except for changing the monomer composition to 65 parts / 15 parts / 7 parts / 13 parts of 2EHA / 2-hydroxyethyl acrylate (HEA) / methyl methacrylate (MMA) / N-vinyl-2-pyrrolidone (NVP), solution polymerization was carried out in the same manner as in synthesis example A1, thereby obtaining a solution of acrylic polymer A4.

[0240] [Synthesis of Polymer (B)]

[0241] 101.15 parts of ethyl acetate, 40 parts of MMA, 20 parts of n-butyl methacrylate (BMA), 20 parts of 2-ethylhexyl methacrylate (2EHMA), 8.7 parts of a methacrylate monomer with a functional group equivalent of 900 g / mol containing a polyorganosiloxane backbone (trade name: X-22-174ASX, manufactured by Shin-Etsu Chemical Co., Ltd.), 11.3 parts of a methacrylate monomer with a functional group equivalent of 4600 g / mol containing a polyorganosiloxane backbone (trade name: KF-2012, manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.8 parts of thioglycerol as a chain transfer agent were added to a four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube, condenser, and dropping funnel. Then, the mixture was stirred at 70°C under a nitrogen atmosphere for 30 minutes, followed by the addition of 0.2 parts of AIBN as a thermal polymerization initiator, and the reaction was carried out at 70°C for 3 hours. Next, after stirring at 80°C for 30 minutes, 0.1 parts of AIBN were added, and the reaction was carried out at 80°C for 2 hours. Subsequently, 0.05 parts of AIBN were added, and the reaction was carried out at 80°C for 2 hours to obtain polymer B. The Mw of the obtained polymer B is 20000.

[0242] It should be noted that the Mw of each of the above polymers was determined using a GPC apparatus (manufactured by Tosoh, HLC-8220GPC) under the following conditions, and was obtained by conversion to polystyrene.

[0243] [GPC Conditions]

[0244] • Sample concentration: 0.2 wt% (tetrahydrofuran (THF) solution)

[0245] • Sample injection volume: 10 μl

[0246] • Elution buffer: THF, Flow rate: 0.6 ml / min

[0247] • Measurement temperature: 40℃

[0248] ·column:

[0249] Sample columns: TSKguardcolumn SuperHZ-H (1 column) + TSKgel SuperHZM-H (2 columns)

[0250] Reference column: TSKgel SuperH-RC (1 column)

[0251] • Detector: Differential refractometer (RI)

[0252] [Enhanced film fabrication]

[0253] <Example 1>

[0254] Add 100 parts of acrylic polymer A1, 2.0 parts of polymer B, and 0.015 parts of isocyanate compound C1 (trade name "Coronate HX", manufactured by Tosoh Corporation) as a crosslinking agent, and dilute with ethyl acetate until the total solid content is 30% to obtain the acrylic adhesive solution of this example.

[0255] A 75 μm thick release liner made of polyester resin (trade name "DIAFOIL MRF75", manufactured by Mitsubishi Chemical Corporation) with one side treated with silicone was prepared. The acrylic adhesive solution obtained above was applied to the silicone-treated side and dried at 130°C for 1 minute to form an adhesive layer with a thickness of 25 μm.

[0256] Next, a 50 μm thick polyimide substrate (trade name "Upilex50S", manufactured by Ube Industries, Ltd.) is bonded to the surface of the obtained adhesive layer to obtain the reinforcing film of this example. The reinforcing film has the form of an adhesive sheet with a release liner, which has an adhesive layer on one side of the substrate and a release liner on its adhesive side.

[0257] It should be noted that, for the reinforcing film in this example, the molar ratio ([NCO] / [OH]) was calculated based on the amount of OH (the number of moles of hydroxyl groups in the acrylic polymer A1) and the amount of NCO (the number of moles of isocyanate groups in the isocyanate compound) in the adhesive layer, and the result was 0.001.

[0258] <Examples 2-5>

[0259] The amount of isocyanate compound C1 was changed as shown in Table 1 to 0.05 parts (Example 2), 0.10 parts (Example 3), 0.20 parts (Example 4), and 0.60 parts (Example 5) of solid content relative to 100 parts of acrylic polymer A1. Otherwise, the acrylic adhesive solutions for each example were obtained in the same manner as in Example 1. Except for using these acrylic adhesive solutions, the reinforcing films for each example were prepared in the same manner as the reinforcing film of Example 1.

[0260] <Examples 6-9>

[0261] The amount of polymer B used was changed as shown in Table 1 to 0.4 parts (Example 6), 1.0 parts (Example 7), 3.0 parts (Example 8), and 6.0 parts (Example 9) relative to 100 parts of acrylic polymer A1. Otherwise, the acrylic adhesive solutions of each example were obtained in the same manner as in Example 3. Except for using these acrylic adhesive solutions, the reinforcing films of each example were prepared in the same manner as the reinforcing films of Example 1.

[0262] <Example 10>

[0263] Except that acrylic polymer A2 was used instead of acrylic polymer A1, the acrylic adhesive solution of this example was obtained in the same manner as in Example 3. Except that the obtained acrylic adhesive solution was used, the reinforcing film of this example was prepared in the same manner as the reinforcing film of Example 1.

[0264] <Example 11>

[0265] Acrylic polymer A3 was used instead of acrylic polymer A1, and isocyanate compound C2 (trade name "Takenate D110N", manufactured by Mitsui Chemicals Co., Ltd.) was used as a crosslinking agent. The isocyanate compound C2 was equivalent to 0.07 parts of solids per 100 parts of acrylic polymer A3. Otherwise, the acrylic adhesive solution of this example was obtained in the same manner as in Example 1. The reinforcing film of this example was prepared in the same manner as the reinforcing film of Example 1, except that the obtained acrylic adhesive solution was used.

[0266] <Examples 12-13>

[0267] The amount of isocyanate compound C2 was changed as shown in Table 1 to 0.09 parts (Example 12) and 0.395 parts (Example 13) of solid content relative to 100 parts of acrylic polymer A3. Otherwise, the acrylic adhesive solutions of each example were obtained in the same manner as in Example 11. Except for using these acrylic adhesive solutions, the reinforcing films of each example were prepared in the same manner as the reinforcing films of Example 1.

[0268] <Examples 14-18>

[0269] In the preparation of the acrylic adhesive solution in Example 3, in addition to acrylic polymer A1, polymer B, and isocyanate compound C1, as shown in Table 1, an iron-based catalyst was further added in amounts equivalent to 0.001 parts (Example 14), 0.005 parts (Example 15), 0.010 parts (Example 16), 0.020 parts (Example 17), and 0.050 parts (Example 18) of 100 parts of acrylic polymer A1 in terms of solid content. Iron(Ⅲ), manufactured by Nippon Chemical Industries Co., Ltd., was diluted with ethyl acetate (98% of the solvent) and acetylacetone (2% of the solvent) until the total solid content was 30% to obtain acrylic adhesive solutions for each example. In addition to using these acrylic adhesive solutions, the reinforcing films for each example were prepared in the same manner as those for the reinforcing film in Example 1. It should be noted that Table 1 also shows the molar ratio of catalyst to hydroxyl groups in the adhesive layer ([catalyst] / [OH]). The above molar ratio ([catalyst] / [OH]) is a value calculated from the amount of OH (the number of moles of hydroxyl groups in the acrylic polymer A1) and the amount of catalyst (the number of moles of catalyst) in the adhesive layer.

[0270] <Examples 19-20>

[0271] The amount of polymer B used was changed as shown in Table 1 to 1.0 part (Example 19) and 3.0 parts (Example 20) relative to 100 parts of acrylic polymer A1. Otherwise, the acrylic adhesive solutions of each example were obtained in the same manner as in Example 14. Except for using these acrylic adhesive solutions, the reinforcing films of each example were prepared in the same manner as the reinforcing films of Example 1.

[0272] <Comparative Example 1>

[0273] 100 parts of acrylic polymer A1 and 0.05 parts of isocyanate compound C1 (trade name "Coronate HX", manufactured by Tosoh Co., Ltd.) as a crosslinking agent were added, and the mixture was diluted with ethyl acetate until the total solid content was 30% to obtain the acrylic adhesive solution of this example. The reinforcing film of this example was prepared in the same manner as the reinforcing film of Example 1, except that the obtained acrylic adhesive solution was used.

[0274] <Comparative Examples 2-3>

[0275] The amount of isocyanate compound C1 was changed to 0.10 parts (Comparative Example 2) and 0.20 parts (Comparative Example 3) of solid content relative to 100 parts of acrylic polymer A1, as shown in Table 1. Otherwise, acrylic adhesive solutions for each example were obtained in the same manner as in Comparative Example 1. Except for using these acrylic adhesive solutions, the reinforcing films for each example were prepared in the same manner as the reinforcing films of Example 1.

[0276] <Comparative Example 4>

[0277] Acrylic polymer A4 was used instead of acrylic polymer A1, and isocyanate compound C2 (trade name "Takenate D110N", manufactured by Mitsui Chemicals Co., Ltd.) was used as a crosslinking agent. The isocyanate compound C2 was converted to 0.50 parts in solids relative to 100 parts of acrylic polymer A4. Otherwise, the acrylic adhesive solution of this example was obtained in the same manner as in Comparative Example 1. Except for using the obtained acrylic adhesive solution, the reinforcing film of this example was prepared in the same manner as the reinforcing film of Example 1.

[0278] <Comparative Examples 5-6>

[0279] The amount of isocyanate compound C2 used was changed to 1.10 parts (Comparative Example 5) and 2.50 parts (Comparative Example 6) of solid content relative to 100 parts of acrylic polymer A4, as shown in Table 1. Otherwise, acrylic adhesive solutions for each example were obtained in the same manner as in Comparative Example 4. Except for using these acrylic adhesive solutions, the reinforcing films for each example were prepared in the same manner as the reinforcing films of Example 1.

[0280] <Comparative Example 7>

[0281] In the preparation of the acrylic adhesive solution, in addition to acrylic polymer A4 and isocyanate compound C2, as shown in Table 1, polymer B was added in the form of 2.0 parts relative to 100 parts of acrylic polymer A4. Otherwise, the acrylic adhesive solution of this example was obtained in the same manner as in Comparative Example 4. Except for using the obtained acrylic adhesive solution, the reinforcing film of this example was prepared in the same manner as the reinforcing film of Example 1.

[0282] <Comparative Examples 8-9>

[0283] The amount of isocyanate compound C2 used was changed to 1.10 parts (Comparative Example 8) and 2.50 parts (Comparative Example 9) of solid content relative to 100 parts of acrylic polymer A4, as shown in Table 1. Otherwise, acrylic adhesive solutions for each example were obtained in the same manner as in Comparative Example 7. Except for using these acrylic adhesive solutions, the reinforcing films for each example were prepared in the same manner as the reinforcing films of Example 1.

[0284] <Evaluation>

[0285] [Surface elastic modulus]

[0286] For each example of reinforcing film, curing 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 adhesive layer surface to an indentation depth of 6 μm using a nanoindenter device (Triboindenter manufactured by Hysitron Inc.). The maximum load (Pmax) [GPa / mm] was obtained by measuring using the aforementioned nanoindenter. 2 Substitute this value into the following formula to calculate the surface hardness, convert it to [kPa] units, and record it as the surface elastic modulus at 23℃ (surface elastic modulus at 23℃). The measurement conditions are as follows. It should be noted that in the above formula, A is the contact projected area of ​​the indenter [mm²]. 2 ].

[0287] Surface hardness [GPa] = Pmax / A

[0288] (Measurement conditions)

[0289] Indenter approach speed: 5μm / s

[0290] Maximum displacement: 6μm

[0291] Indentation speed: 5μm / s

[0292] Extraction speed: 5μm / s

[0293] Indenter used: Conical (spherical indenter: radius of curvature 10μm)

[0294] Measurement method: Single indentation measurement

[0295] Measurement temperature: room temperature (23℃)

[0296] [Bulk modulus G' and tanδ]

[0297] A 75 μm thick release liner R1 (trade name "DIAFOIL MRF75", manufactured by Mitsubishi Chemical Corporation), made of polyester resin and treated with silicone on one side, was prepared. An acrylic adhesive solution of various examples was applied to the silicone-treated side of R1 and dried at 130°C for 1 minute to form an adhesive layer with a thickness of 25 μm. Next, a 75 μm thick release liner R2 (trade name "DIAFOIL MRE75", manufactured by Mitsubishi Chemical Corporation), also treated with silicone on one side, was applied to the surface of the resulting adhesive layer with its silicone-treated side facing the adhesive layer, and cured at 50°C for 1 day.

[0298] Only the obtained adhesive layer is removed, stacked to a thickness of about 1 mm, and punched into φ8 mm cylindrical granules to be used as samples for testing.

[0299] The sample was fixed in a fixture with a parallel plate of φ8mm. Using a dynamic viscoelasticity measuring device (ARES manufactured by TA Instruments), the storage modulus G', loss modulus G'', and loss tangent tanδ were measured under the following conditions. The storage modulus G' at 23℃ was then calculated. 23 [kPa], energy storage modulus G' at 80℃ 80 [kPa] and tanδ at 80℃ (loss modulus G at 80℃) 80 Energy storage modulus G' at 80℃ 80 ).

[0300] Measurement mode: Shear mode

[0301] Temperature range: -70℃~200℃

[0302] • Heating rate: 5℃ / min

[0303] • Frequency: 1Hz

[0304] It should be noted that the storage modulus G' corresponds to the portion of elastic energy stored during material deformation and is an indicator of the degree of hardness. The loss modulus G" corresponds to the portion of energy lost due to internal friction during material deformation and indicates the degree of viscosity.

[0305] [Initial adhesion]

[0306] For each example of reinforcing film, it was cured at 50°C for 1 day and cut together with the release liner into 25mm wide × 140mm long pieces as test samples. The release liner was peeled off from the test sample to expose the adhesive surface, and a 2kg hand roller was used to press it back and forth once to bond it to the stainless steel plate (SUS304BA plate) used as the substrate. After the test sample pressed to the substrate was placed at an ambient temperature of 23°C for 30 minutes, a tensile testing machine (manufactured by Shimadzu Corporation, trade name "Autograph AG-Xplus HS 6000mm / min high-speed mode (AG-50NX plus)") was used to measure the load when the reinforcing film was peeled off from the substrate under the conditions of a peel angle of 180 degrees and a peel speed (tensile speed) of 300mm / min. The average load at the time of measurement was recorded as the initial adhesive force [gf / 25mm].

[0307] [Adhesive strength after heating]

[0308] For each example of the reinforcing film, the test sample was prepared in the same manner as the initial adhesion test described above, and pressed onto the substrate. Then, the test sample pressed onto the substrate was heated at an ambient temperature of 60°C for 60 minutes. Afterward, it was placed at an ambient temperature of 23°C for 30 minutes, and the load when peeling the reinforcing film from the substrate was measured using a tensile testing machine (manufactured by Shimadzu Corporation, trade name "Autograph AG-Xplus HS 6000mm / min high-speed mode (AG-50NX plus)") at a peel angle of 180 degrees and a peel speed (tensile speed) of 300mm / min. The average load at the time of measurement was recorded as the adhesive force after heating [gf / 25mm].

[0309] [Bending retention test]

[0310] For each example of the reinforcing film, after curing at 50°C for 1 day, the release liner was peeled off, and a 25μm thick polyimide substrate (trade name "Upilex 25S", manufactured by Ube Industries, Ltd.) was bonded to the exposed adhesive surface. The substrate was then heated at 60°C for 60 minutes to ensure a tight seal. Next, the resulting test sample (laminate) was bent to φ6mm with the 25μm substrate side as the inside, fixed in this state, and heated at 80°C for 15 hours. Then, it was placed at room temperature (23°C) and, after confirming sufficient cooling, the bending state of the test sample was released. Within 10 minutes of releasing the fixation, the bending angle [°] of the bent test sample was measured using a scaler to evaluate the bending recovery. It should be noted that the bending angle is the opening angle of the test sample (the angle of the side of the test sample opened from the bent state). The closer to 180°, the better the bending recovery; the closer the bending angle is to 0°, the worse the bending recovery.

[0311] Next, as an evaluation of bending retention, the bending portion of the test sample is visually inspected for "peeling". Cases where "peeling" is not detected are rated as "G (Good)" and cases where "peeling" is detected are rated as "P (Poor)".

[0312] [Bubble generation confirmation]

[0313] For each case of reinforcing film, after curing at 50°C for 1 day, it is cut into 10cm×10cm sizes, the release liner is peeled off, the amount of air bubbles generated per 10cm square is visually confirmed, and the evaluation is carried out according to the following criteria.

[0314] E (Excellent): No bubble generation detected.

[0315] G (Good): Bubble formation is confirmed, but the area of ​​bubble formation is less than 50% per 10cm square.

[0316] A (Tolerable): Bubble formation is confirmed in an area of ​​more than 50% per 10cm square. However, this level is acceptable for practical applications.

[0317] The evaluation results of the reinforcing films for each example are shown in Table 1. Table 1 also shows a general outline of the composition of the adhesive layer for each example.

[0318] [Table 1]

[0319]

[0320] As shown in Table 1, the adhesives of Examples 1-20 contain polymer (A) and polymer (B), and compared with Comparative Examples 1-6, which do not contain polymer (B), the initial adhesive force is suppressed to a lower level. Furthermore, the adhesive force of the adhesives of Examples 1-20 increases significantly upon heating. Moreover, the surface elastic modulus of the adhesive layer of the reinforcing film of Examples 1-20 at 23°C is in the range of 1-20 kPa, and the flexural recovery and flexural holding force are also good. On the other hand, in Comparative Examples 4-9, where the surface elastic modulus at 23°C is outside the range of 1-20 kPa, peeling was confirmed in the flexural holding test.

[0321] More specifically, a comparison of Examples 1-5 confirmed the following trend: the higher the surface elastic modulus of the adhesive layer at 23°C in the range of 1-20 kPa, the better the flexural recovery, and the lower the initial adhesion and the adhesion after heating. Examples 2-5 exhibited better flexural recovery than Example 1, with a surface elastic modulus at 23°C of 2 or higher, and a tanδ value at 80°C. 80 The values ​​are in the range of 0.10 to 0.60. Furthermore, in Example 5, both the surface elastic modulus and the bulk elastic modulus are high, and the increase in adhesive strength after heating is relatively low compared to Examples 1-4. Additionally, compared to the other examples mentioned above, there is a tendency for more bubbles to form on the adhesive layer surface. In Examples 2-4, where the initial adhesive strength, adhesive strength after heating, flexural recovery, and flexural holding force are improved more evenly, the molar ratio of isocyanate groups to hydroxyl groups ([NCO] / [OH]) in the adhesive layer is in the range of 0.002 to 0.03. Furthermore, in Examples 1-4, the bulk elastic modulus G' of the adhesive layer at 23°C was not confirmed. 23 The differences. Furthermore, regarding Examples 2-3, the bulk modulus G' at 80°C... 80 No differences were identified. Regarding Examples 1-5, the surface elastic modulus at 23°C showed a higher correlation with flexural resilience compared to the bulk elastic modulus.

[0322] Furthermore, the comparison of Examples 6-9 confirmed a tendency for decreasing adhesive strength as the amount of polymer (B) increases. In Examples 7-8, where the amount of polymer (B) used was in the range of 0.5 to 5 parts per 100 parts of polymer (A), the initial adhesive strength was less than 500 gf / 25 mm, but the adhesive strength after heating was more than 500 gf / 25 mm, better balancing the initial easy peeling and the increase in adhesive strength after heating. In addition, there was a tendency that the higher the amount of polymer (B) used, the higher the surface elastic modulus at 23°C and the lower the flexural recovery. Furthermore, the results of Examples 10-13 confirmed that the desired effect could be achieved even by changing the type of polymer (A) and crosslinking agent in the adhesive. Compared to Examples 12-13, the increase in adhesive strength after heating was greater in Examples 10-11.

[0323] Furthermore, in Examples 14-20, the generation of bubbles can be prevented by using a catalyst. The amount of iron-based catalyst used is such that the molar ratio of the catalyst to the hydroxyl groups in the binder layer ([catalyst] / [OH]) is 4.6E-5 (4.6 × 10⁻⁵). -5 )~9.2E-4(9.2×10 -4 In Examples 14-17 and 19-20, the adhesive strength increased significantly after heating, relative to the initial low adhesive strength. In particular, Example 19 showed the most balanced improvement in initial adhesive strength, adhesive strength after heating, flexural resilience, flexural holding force, and prevention of bubble formation.

[0324] The specific examples of the present invention have been described in detail above, but these are merely illustrative and do not limit the scope of protection of the claims. The solutions described in the claims include solutions obtained by various modifications and alterations to the specific examples described above.

[0325] Explanation of reference numerals in the attached figures

[0326] 1,2,3 Reinforcing film

[0327] 10 Supporting Substrates

[0328] 10A First Page

[0329] 10B Second Side

[0330] 21 Adhesive layer (first adhesive layer)

[0331] 21A Adhesive Surface (First Adhesive Surface)

[0332] 21B Adhesive Surface (Second Adhesive Surface)

[0333] 22 Adhesive layer (second adhesive layer)

[0334] 22A Adhesive Surface (Second Adhesive Surface)

[0335] 31,32 Peeling gasket

[0336] 100, 200, 300 Reinforcing films with release liner

Claims

1. A reinforcing film comprising an adhesive layer, The adhesive layer comprises polymer (A) and polymer (B). The polymer (A) is an acrylic polymer. The acrylic polymer contains more than 1% by weight and less than 20% by weight of monomer units derived from hydroxyl-containing monomers. The glass transition temperature T of the polymer (A) A Temperatures above -80°C and below -35°C The polymer (B) comprises monomer units having a polyorganosiloxane backbone and (meth)acrylic acid monomer units. The content of polymer (B) in the adhesive layer is 0.1 to 30 parts by weight relative to 100 parts by weight of polymer (A). The adhesive layer comprises an isocyanate-based crosslinking agent in an amount of 0.015 parts by weight and less than 1.0 parts by weight relative to 100 parts by weight of the polymer (A). The molar ratio of isocyanate groups to hydroxyl groups in the adhesive layer, i.e., [NCO] / [OH], is 0.002~0.

03. The surface elastic modulus of the adhesive layer at 23°C is 1~20 kPa.

2. The reinforcing film according to claim 1, wherein, The bulk modulus of elasticity G' of the adhesive layer at 23°C 23 The bulk modulus G' is 10~200 kPa at 80℃. 80 The tanδ value is 5~100 kPa and at 80℃. 80 The value is 0.10~0.

60.

3. The reinforcing film according to claim 1 or 2, wherein, The content of polymer (B) in the adhesive layer is 0.5 to 5 parts by weight relative to 100 parts by weight of polymer (A).

4. The reinforcing film according to claim 1 or 2, wherein, The adhesive layer contains a catalyst. The molar ratio of the catalyst to hydroxyl groups contained in the adhesive layer, i.e., [catalyst] / [OH], is 1.0 × 10⁻⁶. -6 ~5.0×10 -2 .

5. The reinforcing film according to claim 4, wherein, The catalyst is an iron-based catalyst. The molar ratio of the catalyst to hydroxyl groups in the adhesive, i.e., [catalyst] / [OH], is 1.0 × 10⁻⁶. -4 ~1.0×10 -3 .

6. An optical component having a reinforcing film attached to it according to any one of claims 1 to 5.

7. An electronic component having a reinforcing film attached to it according to any one of claims 1 to 5.

Images