CN116034027A - Reinforcing film, optical member, and electronic member - Google Patents

Reinforcing film, optical member, and electronic member Download PDF

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Publication number
CN116034027A
CN116034027A CN202180057328.5A CN202180057328A CN116034027A CN 116034027 A CN116034027 A CN 116034027A CN 202180057328 A CN202180057328 A CN 202180057328A CN 116034027 A CN116034027 A CN 116034027A
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polymer
monomer
meth
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weight
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佐佐木翔悟
舟木千寻
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Nitto Denko Corp
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Nitto Denko Corp
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • C09J7/385—Acrylic polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L43/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and containing boron, silicon, phosphorus, selenium, tellurium or a metal; Compositions of derivatives of such polymers
    • C08L43/04—Homopolymers or copolymers of monomers containing silicon
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J143/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and containing boron, silicon, phosphorus, selenium, tellurium, or a metal; Adhesives based on derivatives of such polymers
    • C09J143/04—Homopolymers or copolymers of monomers containing silicon
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J151/00—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
    • C09J151/06—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
    • C09J175/04—Polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/20—Displays, e.g. liquid crystal displays, plasma displays

Abstract

The present invention provides a reinforcing film which can exhibit light peelability at the initial stage of adhesion to an adherend, and after that, can greatly increase the adhesive force, and has bending recovery property and bending retention force. The reinforcing film is provided with an adhesive layer. The adhesive layer contains a polymer (A) and a polymer (B). The polymer (B) contains a monomer unit having a polyorganosiloxane skeleton and a (meth) acrylic monomer unit. The adhesive layer has a surface elastic modulus at 23 ℃ of 1 to 20kPa. Further, the glass transition temperature T of the polymer (B) B Is at a temperature of between-20 ℃ and 5 ℃.

Description

Reinforcing film, optical member, and electronic member
Technical Field
The present invention relates to a reinforcing film, and an optical member and an electronic component to which the reinforcing film is attached. The present application claims priority based on japanese patent application No. 2020-134188, filed 8/6 in 2020, the entire contents of which are incorporated herein by reference.
Background
For the purpose of adhesion of adherends to each other, fixation of articles to adherends, and the like, adhesives are widely used in various applications such as portable electronic devices such as mobile phones, smart phones, tablet personal computers, and other electronic devices in the form of adhesive sheets. For example, the pressure-sensitive adhesive sheet is used as a reinforcing material (reinforcing film) for imparting rigidity and impact resistance to optical members, electronic members, and the like constituting the aforementioned devices. Patent documents 1 and 2 are examples of documents that disclose such prior art.
In recent years, portable electronic devices capable of bending or curling have been attracting attention, and an adhesive sheet usable for fixing flexible devices (typically, image display devices such as organic EL and liquid crystal display devices) built in such electronic devices has been developed (patent documents 3 to 6).
On the other hand, in view of the performance of the adhesive, recently, an adhesive sheet has been proposed which can exhibit low adhesive force at the initial stage of attachment to an adherend and thereafter greatly increase the adhesive force (patent document 7). According to the adhesive sheet having such characteristics, it is possible to exhibit re-adhesiveness (reworkability) which is useful for suppressing a reduction in yield due to a misattachment or a sticking failure of the adhesive sheet before the adhesive force increases, and to exhibit strong adhesive properties suitable for the intended use of the adhesive sheet after the adhesive force increases.
Prior art literature
Patent literature
Patent document 1: japanese patent No. 6366199
Patent document 2: japanese patent No. 6366200
Patent document 3: japanese patent No. 6376271
Patent document 4: japanese patent application laid-open No. 2016-108555
Patent document 5: japanese patent application laid-open No. 2017-095657
Patent document 6: japanese patent application laid-open No. 2017-095659
Patent document 7: japanese patent No. 6373458
Disclosure of Invention
Problems to be solved by the invention
The stiffening film may also be used in the aforementioned flexible devices. For example, in the production of the flexible device, since the members constituting the device are often thin, it is desirable to attach an adhesive sheet as a reinforcing film for reinforcement, to prevent defects caused by deformation of the device, or to improve operability. Since the flexible device can be repeatedly bent or curved, a reinforcing film for the flexible device is required to have a characteristic (bending recovery) that normally recovers a shape even in the case of repeated bending, and a characteristic (bending retention force) that does not cause a problem such as peeling. Such a reinforcing film having a bending recovery property and a bending holding force is useful because it can be used for various applications including flexible devices, and therefore, has a small limitation in application range.
For example, as proposed in patent document 7, it is desirable that an adhesive agent which is configured to exhibit low adhesive force at the initial stage of attachment and to have greatly increased adhesive force thereafter has bending recovery property and bending holding force even when used as a reinforcing film. As one method for improving the bending holding force, for example, a method of appropriately setting the storage modulus of an adhesive is considered. However, when the storage modulus of the adhesive designed to increase the adhesive strength is changed as described above, both the initial low adhesive strength and the adhesive strength after the increase are affected. Further, in addition to the bending holding force, it is not easy to satisfy all of these characteristics in consideration of bending recovery. The adhesive agent which exhibits low adhesive force at the initial stage of application and then greatly increases adhesive force is useful in practical applications as long as it can improve bending recovery and bending retention.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a reinforcing film which can exhibit light peelability at the initial stage of attachment to an adherend, and thereafter greatly increase the adhesive force, and which has bending recovery properties and bending holding force. Another object of the present invention is to provide an optical member and an electronic component to which the reinforcing film is bonded.
Solution for solving the problem
According to the present specification, a reinforcing film having an adhesive layer can be provided. The adhesive layer contains a polymer (A) and a polymer (B). The polymer (B) contains a monomer unit having a polyorganosiloxane skeleton and a (meth) acrylic monomer unit. The adhesive layer has a surface elastic modulus at 23 ℃ of 1 to 20kPa. Further, the glass transition temperature T of the polymer (B) B Is at a temperature of between-20 ℃ and 5 ℃.
According to the above configuration, since the pressure-sensitive adhesive layer contains the polymer (a) and the polymer (B) containing the monomer unit having the polyorganosiloxane skeleton, it is possible to exhibit light releasability at the initial stage of application to an adherend, and thereafter, the adhesive force can be greatly increased. In addition, by adjusting the glass transition temperature (Tg) T of the polymer (B) B At a temperature of-20deg.C or higher, the adhesive composition tends to be excellent in light releasability at the initial stage of adhesion, and the T is used as a solvent B At 5 ℃ or lower, the adhesive strength is liable to be excellent. The reinforcing film has a bending recovery property and a bending holding force. Specifically, a reinforced film having an adhesive layer with a surface elastic modulus at 23 ℃ (surface elastic modulus at 23 ℃) of 1kPa or more exhibits the above adhesive properties and has good bending recovery. In addition, when the adhesive layer has a surface elastic modulus of 20kPa or less at 23 ℃, the adhesive property is exhibited and the adhesive layer has a good bending retention force, and thus, even when the adhesive layer is used in a repeated bending manner, defects such as peeling are less likely to occur.
In some preferred embodiments of the technology disclosed herein (including reinforcing films, optical members, and electronic members, the same applies hereinafter), the adhesive layer has a bulk modulus G 'at 23℃' 23 Is 10 to 200kPa. By using the bulk modulus G 'having this range' 23 Is attached to the substrate at the initial stage of attachmentThe adhesive force of (2) is easily in a suitable range with excellent light peelability. In addition, the workability is excellent, and generally, it tends to be easy to achieve both strain relaxation property and bending recovery property in the normal temperature range.
In some preferred embodiments, the adhesive layer has a bulk modulus G 'at 80℃' 80 Is 5 to 100kPa. Having a bulk modulus G 'in this range' 80 Generally, the adhesive of (c) is easy to combine both bending recovery and bending retention. For example, even when the adhesive is used at a high temperature of about 80 ℃, the adhesive can have elasticity suitable for bending recovery and can have adhesive holding force for realizing bending holding force.
In some preferred embodiments, the adhesive layer has a tan delta at 80 DEG C 80 0.10 to 0.60. The aforementioned tan delta 80 (loss modulus G "at 80 ℃ C.)" 80 Storage modulus G 'at 80 ℃' 80 ) An adhesive of 0.10 or more easily exerts an adhesive force suitable for retaining bending. Further, by making the aforementioned tan delta 80 When the amount is 0.60 or less, plastic deformation of the adhesive is easily suppressed, and good bending recovery is obtained. In addition, even when the reinforcing film is held in a bent state for a long period of time, a holding force (bending holding force) that does not peel off from the adherend is easily exerted.
The polymer (a) is preferably an acrylic polymer. The effects of the techniques disclosed herein can be preferably achieved by using an adhesive layer comprising the polymer (a) as an acrylic polymer and the polymer (B) containing a monomer unit having a polyorganosiloxane skeleton.
In some preferred embodiments, the content of the polymer (B) in the adhesive layer is 0.5 to 5 parts by weight relative to 100 parts by weight of the polymer (a). By setting the amount of the polymer (B) to 0.5 parts by weight or more relative to 100 parts by weight of the polymer (a), light peelability at the initial stage of attachment is easily obtained. By setting the amount of the polymer (B) to 5 parts by weight or less, the targeted increase in adhesive force can be easily achieved. Further, by setting the amount of the polymer (B) to the above range, good bending recovery and bending retention can be easily achieved.
In some preferred embodiments, the molar ratio ([ NCO ]/[ OH ]) of isocyanate groups to hydroxyl groups contained in the adhesive layer is 0.002 to 0.03. The pressure-sensitive adhesive layer having the molar ratio ([ NCO ]/[ OH) of 0.002 or more tends to be excellent in bending recovery properties and also tends to be excellent in processability. Further, when the molar ratio ([ NCO ]/[ OH ]) is 0.03 or less, an appropriate increase in adhesion tends to be easily achieved. In the adhesive layer, isocyanate groups and hydroxyl groups may be present in a state in which at least a part of them is chemically bonded (crosslinked). The pressure-sensitive adhesive layer contains, for example, a crosslinking agent, and in this configuration, the isocyanate group may be, for example, a part of the crosslinking agent, and the hydroxyl group may be, for example, a part of the polymer (a).
The reinforcing film disclosed herein is suitable as a reinforcing film for imparting rigidity and impact resistance to an optical member such as a polarizing plate or a wavelength plate during processing or transportation of the optical member. Therefore, according to the present specification, an optical member to which any of the reinforcing films disclosed herein is attached can be provided.
The reinforcing film disclosed herein is also suitable for use as a reinforcing film for electronic components of devices such as portable electronic devices. Therefore, according to the present specification, an electronic component to which any of the reinforcing films disclosed herein is attached can be provided.
Drawings
Fig. 1 is a cross-sectional view schematically showing the structure of a reinforcing film according to an embodiment.
Fig. 2 is a cross-sectional view schematically showing the structure of a reinforcing film according to another embodiment.
Fig. 3 is a cross-sectional view schematically showing the structure of a reinforcing film according to another embodiment.
Detailed Description
Hereinafter, preferred embodiments of the present invention will be described. The matters necessary for the practice of the present invention other than those specifically mentioned in the present specification can be understood by those skilled in the art based on the teachings and technical knowledge of the present specification at the time of application for the practice of the present invention. The present invention can be implemented based on the disclosure of the present specification and the technical common knowledge in the field.
In the following drawings, members and portions that perform the same function may be denoted by the same reference numerals, and overlapping description may be omitted or simplified. The embodiments described in the drawings are schematically shown for clarity of explanation of the present invention, and do not necessarily accurately represent the dimensions and scale of the product actually provided.
In the present specification, the "acrylic polymer" means a polymer containing a monomer unit derived from a (meth) acrylic monomer in a polymer structure, and typically means a polymer containing a monomer unit derived from a (meth) acrylic monomer in a proportion of more than 50% by weight. Further, the (meth) acrylic monomer means a monomer having at least one (meth) acryloyl group in 1 molecule. Here, "(meth) acryl" is meant to include acryl and methacryl. Accordingly, the concept of the (meth) acrylic monomer herein may include both a monomer having an acryl group (acrylic monomer) and a monomer having a methacryl group (methacrylic monomer). Similarly, in the present specification, "(meth) acrylic acid" is defined to include acrylic acid and methacrylic acid, and "(meth) acrylic acid ester" is defined to include acrylic acid ester and methacrylic acid ester.
Structural example of reinforcing film
The reinforcing film disclosed herein has the form of an adhesive sheet having an adhesive face formed of an adhesive. The pressure-sensitive adhesive sheet used as the reinforcing film includes a pressure-sensitive adhesive layer. The reinforcing film disclosed herein may be in the form of a base-material-equipped adhesive sheet having the adhesive layer laminated on one or both surfaces of the support base material, or may be in the form of a base-material-free adhesive sheet having no support base material.
In the present specification, the term "reinforcing film" refers to an adhesive sheet (reinforcing adhesive film) for reinforcing an adherend as described later. The reinforcing film is not limited to the form of the adhesive sheet with a base material, for example, since it may be formed by attaching a support material or the like to one adhesive surface and then attaching the other adhesive surface to an adherend to be reinforced. In this regard, the concept is understood to be broader than the following "reinforcing film" having the form of the adhesive sheet with a base material.
Fig. 1 schematically shows the structure of a reinforcing film according to an embodiment. The reinforcing film 1 is configured as a single-sided adhesive sheet with a base material, which includes a sheet-like support base material 10 having a first surface 10A and a second surface 10B, and an adhesive layer 21 provided on the first surface 10A side. The adhesive layer 21 is fixedly connected to the first surface 10A side of the support substrate 10. The reinforcing film 1 is used by attaching the adhesive layer 21 to an adherend. As shown in fig. 1, the reinforcing film 1 before use (i.e., before attachment to an adherend) may be a component of the reinforcing film 100 with a release liner, and the reinforcing film 100 with a release liner may be in a form in which a surface (adhesive surface) 21A of the adhesive layer 21 is in contact with a release liner 31 which is a releasable surface (release surface) at least on the side opposite to the adhesive layer 21. As the release liner 31, for example, a release liner having a release layer formed of a release treatment agent provided on one surface of a sheet-like substrate (liner substrate) so that the one surface becomes a release surface can be preferably used. Alternatively, the release liner 31 may be omitted, and the support base material 10 having the second surface 10B as the release surface may be used, and the adhesive surface 21A may be brought into contact with the second surface 10B of the support base material 10 by winding the reinforcing film 1 (roll form). When the reinforcing film 1 is attached to an adherend, the release liner 31 or the second surface 10B of the support substrate 10 is peeled off from the adhesive surface 21A, and the exposed adhesive surface 21A is pressure-bonded to the adherend.
Fig. 2 schematically shows the structure of a reinforcing film according to another embodiment. The reinforcing film 2 is configured as a base-material-equipped double-sided adhesive sheet having a sheet-like support base material 10 having a first surface 10A and a second surface 10B, an adhesive layer 21 provided on the first surface 10A side, and an adhesive layer 22 provided on the second surface 10B side. The adhesive layer (first adhesive layer) 21 is fixedly connected to the first surface 10A of the support substrate 10, and the adhesive layer (second adhesive layer) 22 is fixedly connected to the second surface 10B of the support substrate 10. The reinforcing film 2 is used by attaching the pressure-sensitive adhesive layers 21, 22 to different portions of an adherend. The adhesive layers 21 and 22 may be attached to the respective parts of the different members or may be attached to the different parts in a single member. As shown in fig. 2, the reinforcing film 2 before use may be a component of the reinforcing film 200 with a release liner, and the reinforcing film 200 with a release liner may be in a form in which a surface (first adhesive surface) 21A of the adhesive layer 21 and a surface (second adhesive surface) 22A of the adhesive layer 22 are in contact with release liners 31 and 32, which are release surfaces, respectively, at least on the side facing the adhesive layers 21 and 22. As the release liners 31 and 32, for example, release liners having a release layer formed of a release treatment agent provided on one surface of a sheet-like substrate (liner substrate) so that the one surface becomes a release surface can be preferably used. Alternatively, the release liner 32 may be omitted, and the release liner 31 having both surfaces as release surfaces may be used, and the release liner-attached reinforcing film may be wound in a spiral shape so that the second adhesive surface 22A is in contact with the back surface of the release liner 31 (in a roll shape) by overlapping the release liner with the reinforcing film 2.
Fig. 3 schematically shows the structure of a reinforcing film according to still another embodiment. The reinforcing film 3 is constituted by a base-material-free double-sided pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer 21. The reinforcing film 3 is used by attaching a first adhesive surface 21A formed of one surface (first surface) of the adhesive layer 21 and a second adhesive surface 21B formed of the other surface (second surface) of the adhesive layer 21 to different portions of an adherend. As shown in fig. 3, the reinforcing film 3 before use may be a component of a reinforcing film 300 with a release liner, and the reinforcing film 300 with a release liner may be in a form in which the first adhesive surface 21A and the second adhesive surface 21B are in contact with release liners 31 and 32, which are release surfaces, respectively, at least on the side facing the adhesive layer 21. Alternatively, the release liner 32 may be omitted, and the release liner 31 having both surfaces as release surfaces may be used, and the release liner-attached reinforcing film may be wound in a spiral shape so that the second adhesive surface 21B is in contact with the back surface of the release liner 31 (in a roll shape) by overlapping the release liner with the reinforcing film 3.
The reinforcing film may be in a roll form, a single sheet form, or a form in which it is cut or die-cut into a suitable shape according to the application and use. The pressure-sensitive adhesive layer in the technology disclosed herein is typically formed continuously, but is not limited thereto, and may be formed in a regular or irregular pattern such as a dot shape, a stripe shape, or the like, for example.
< adhesive layer >)
The reinforcing film disclosed herein comprises an adhesive layer containing a polymer (A) and a polymer (B). Such an adhesive layer may be formed of an adhesive composition containing a polymer (a) which is a complete polymer or a partial polymer of the monomer raw material a, and a polymer (B). The form of the adhesive composition is not particularly limited, and may be various forms such as solvent-based, water-dispersible, hot-melt, active energy ray-curable (e.g., photo-curable), and the like.
(surface elastic modulus at 23 ℃ C.)
The adhesive layer disclosed herein is characterized in that the surface (adhesive face) thereof has a surface elastic modulus at 23 ℃ (23 ℃ surface elastic modulus) in the range of 1 to 20 kPa. By setting the surface elastic modulus at 23℃to 1kPa or more, the adhesive properties based on the polymer (A) and the polymer (B) can be achieved, and the adhesive composition has good bending recovery properties. Further, by setting the surface elastic modulus to 20kPa or less, the adhesive property can be achieved and a good bending holding force can be exerted.
The surface elastic modulus at 23℃is preferably 2kPa or more, more preferably 3kPa or more, further preferably 4kPa or more (e.g., 5kPa or more), and may be 8kPa or more, 10kPa or more, or 12kPa or more (e.g., 14kPa or more) from the viewpoint of improving bending recovery properties. The higher the surface elastic modulus is, the more excellent the initial light peelability tends to be. Further, from the viewpoint of both good bending recovery and bending retention, and preferably exhibiting an increase in adhesive force, the surface elastic modulus at 23 ℃ is preferably 15kPa or less, more preferably 12kPa or less, still more preferably 9kPa or less, still more preferably 7kPa or less (for example, 6kPa or less), and may be 4kPa or less.
The surface elastic modulus at 23℃of the adhesive layer can be adjusted by the kind and property (molecular weight, glass transition temperature, molecular structure, etc.) of the polymer (A), the kind (chemical structure, etc.) of the polymer (B), the property (molecular weight, glass transition temperature, etc.), the amount used, the kind of crosslinking agent, the amount used, etc. The surface elastic modulus at 23℃of the adhesive layer was measured by the method described in the following examples.
(bulk modulus of elasticity G 'at 23 ℃ C.)' 23 )
Bulk modulus G 'of the adhesive layer at 23℃' 23 (bulk modulus of elasticity G 'at 23 ℃ C.)' 23 ) The surface elastic modulus at 23℃is appropriately set within a range satisfying the above-mentioned range, and is not limited to a specific range. In some embodiments, the adhesive layer has a bulk modulus of elasticity G 'at 23℃' 23 Preferably 10kPa or more. By combining the bulk modulus G' 23 When the adhesive force is equal to or greater than a predetermined value, the adhesive force at the initial stage of adhesion is easily in a suitable range with excellent light peelability. Further, the workability is excellent, and in general, the bending recovery property in the normal temperature range tends to be excellent. The bulk modulus G' 23 Preferably 15kPa or more, more preferably 20kPa or more, further preferably 25kPa or more, particularly preferably 30kPa or more. In other embodiments, the bulk modulus G' 23 May be 50kPa or more, may be 80kPa or more, or may be 100kPa or more.
In some embodiments, the adhesive layer has a bulk modulus of elasticity G 'at 23℃' 23 Preferably 200kPa or less. The bulk modulus G' 23 An adhesive having a predetermined value or less generally tends to be excellent in strain relaxation property in a normal temperature region, and further tends to exhibit an increase in adhesive force. The bulk modulus G' 23 Preferably 150kPa or less, more preferably 90kPa or less. In some preferred embodiments, the bulk modulus G' 23 May be 60kPa or less, or may be 40kPa or less (for example, 35kPa or less).
(bulk modulus of elasticity G 'at 80 ℃ C.)' 80 )
Bulk modulus G 'of the adhesive layer at 80℃' 80 (bulk modulus of elasticity G 'at 80 ℃ C.)' 80 ) At a temperature of 23 DEG CThe range of the surface elastic modulus is appropriately set and is not limited to a specific range. In some embodiments, the adhesive layer has a bulk modulus of elasticity G 'at 80℃' 80 Preferably 5kPa or more. By combining the bulk modulus G' 80 When the bending recovery property is equal to or higher than a predetermined value, the bending recovery property is easily improved, and the bending recovery property is improved even when the bending recovery device is used under high-temperature conditions. In some preferred embodiments, the bulk modulus G' 80 The pressure may be 7kPa or more, 9kPa or more, or 10kPa or more. In other embodiments, the bulk modulus G' 80 May be 15kPa or more, may be 30kPa or more, or may be 50kPa or more.
In some embodiments, the adhesive layer has a bulk modulus of elasticity G 'at 80℃' 80 Preferably, the pressure is 100kPa or less. By combining the bulk modulus G' 80 In general, a good bending retention force is easily obtained by limiting the bending retention force to a predetermined value or less, and both bending recovery and bending retention force are easily achieved. For example, the adhesive holding force can be provided under various environments including high temperature conditions, with elasticity suitable for bending recovery, and with an adhesive holding force for realizing bending holding force. The bulk modulus G' 80 Preferably 90kPa or less, more preferably 60kPa or less. In some embodiments, the bulk modulus G' 80 May be 20kPa or less, 16kPa or less, or 14kPa or less (for example, 12kPa or less).
(80℃tanδ 80 )
Tan delta of adhesive layer at 80 DEG C 80 (80℃tanδ 80 ) The range satisfying the above 23 ℃ surface elastic modulus is not limited to a specific range. In some embodiments, the adhesive layer has a tan delta at 80 degrees celsius 80 Preferably, the ratio is 0.10 or more. The tan delta 80 The higher the adhesive, the easier the adhesive agent exerts an adhesive force suitable for bending retention. The tan delta 80 Preferably 0.20 or more. In some preferred embodiments, the tan delta 80 The content may be 0.30 or more, 0.40 or more, or 0.45 or more.
In some embodiments, the adhesive layer has a tan delta at 80 degrees celsius 80 Preferably 0.60 or less. By making the following stepsThe tan delta 80 When the amount is 0.60 or less, plastic deformation of the adhesive can be suppressed, and good bending recovery property can be easily obtained. In addition, even when the reinforcing film is held in a curved state for a long period of time, the holding force is easily exerted so that peeling from the adherend does not occur. Further, the adhesive force increases easily to a suitable level. The temperature of tan delta at 80 DEG C 80 May be 0.55 or less. In other embodiments, the temperature of tan delta at 80 DEG C 80 May be 0.50 or less, or 0.35 or less.
Bulk modulus G 'at 23℃of adhesive layer' 23 Bulk modulus G 'at 80 ℃' 80 Tan delta at 80 DEG C 80 The type, the characteristics (molecular weight, glass transition temperature, molecular structure, etc.) of the polymer (a), the type (chemical structure, etc.) of the polymer (B), the characteristics (molecular weight, glass transition temperature, etc.), the amount of the crosslinking agent used, etc. can be adjusted. Bulk modulus G 'at 23℃of adhesive layer' 23 Bulk modulus G 'at 80 ℃' 80 Tan delta at 80 DEG C 80 The measurement was performed by the method described in the following examples.
(Polymer (A))
As the polymer (a), one or two or more of various polymers exhibiting rubber elasticity in a room temperature region, such as an acrylic polymer, a rubber polymer, a polyester polymer, a urethane polymer, a polyether polymer, a silicone polymer, a polyamide polymer, and a fluorine polymer, which are known in the adhesive field, can be used. In the reinforcing film disclosed herein, the polymer (a) is typically a main component of the polymer component contained in the adhesive layer, that is, a component accounting for more than 50% by weight, and may be, for example, a component accounting for 75% by weight or more of the above polymer components. In some embodiments, the polymer (a) may be a component that occupies more than 50 wt% of the entire adhesive layer, may occupy more than 70 wt%, may occupy more than 80 wt%, may occupy more than 90 wt%, or may occupy more than 95 wt% (e.g., 97 wt% or more).
Glass transition temperature T of Polymer (A) A Is not particularly limited, and canSelected in such a way that the reinforcement film disclosed herein obtains the preferred properties. In some ways, T may be preferred A A polymer (A) at a temperature of less than 0 ℃. Since the adhesive containing such a polymer (a) exhibits moderate fluidity (for example, the mobility of the polymer chains contained in the adhesive), it is suitable for realizing a reinforcing film in which the adhesive force is increased to a predetermined value or more by heating. The reinforcing film disclosed herein may be T-shaped A The polymer (A) is preferably carried out at a temperature of less than-10 ℃, less than-20 ℃, less than-30 ℃ or less than-35 ℃. In some embodiments, T A The temperature may be less than-40℃or less than-50 ℃. In some preferred modes, T A The temperature is-55℃or lower, more preferably-58℃or lower, still more preferably-62℃or lower, and may be-65℃or lower (for example, -66℃or lower). T (T) A The lower limit of (2) is not particularly limited. T is generally preferably used from the viewpoints of easiness in acquisition of materials and improvement of cohesive force of the adhesive layer A A polymer (A) having a temperature of-80 ℃ or higher and a temperature of-70 ℃ or higher. In some embodiments, T A For example, the temperature may be-63℃or higher, may be-55℃or higher, may be-50℃or higher, or may be-45℃or higher.
In the present specification, the glass transition temperature (Tg) of a polymer (for example, the glass transition temperature of a polymer (a), a polymer (B) described below, and the like) refers to a nominal value described in literature, catalogues, and the like, or Tg obtained from Fox expression based on the composition of monomer raw materials used for preparing the polymer. The Fox formula is shown below, and is a relation between Tg of the copolymer and glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer.
1/Tg＝Σ(Wi/Tgi)
In the above Fox formula, tg represents the glass transition temperature (unit: K) of the copolymer, wi represents the weight fraction (copolymerization ratio based on weight) of the monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i. In the case where the target polymer whose Tg is to be determined is a homopolymer, the Tg of the homopolymer coincides with the Tg of the target polymer.
As the glass transition temperature of the homopolymer used for calculating Tg, the values described in known data were used. Specifically, the values are listed in "Polymer handbook" (3 rd edition, john Wiley & Sons, inc., 1989). The highest value is used for the monomers described in the above polymer handbook for various values.
As the glass transition temperature of the homopolymer of the monomer not described in the above polymer handbook, the values obtained by the following measurement methods were used.
Specifically, 100 parts by weight of monomer, 0.2 part by weight of 2,2' -azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent were charged into a reactor equipped with a thermometer, a stirrer, a nitrogen inlet pipe and a reflux condenser, and stirred for 1 hour while flowing nitrogen. After oxygen in the polymerization system was thus removed, the temperature was raised to 63℃and allowed to react for 10 hours. Then, the mixture was cooled to room temperature to obtain a homopolymer solution having a solid content of 33% by weight. Subsequently, the homopolymer solution was cast on a release liner and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm. The test specimen was punched into a disk shape having a diameter of 7.9mm and held by parallel plates, and the viscoelasticity was measured by a shear mode at a temperature range of-70 to 150 ℃ at a temperature rise rate of 5 ℃/min while a shear strain having a frequency of 1Hz was applied by a viscoelasticity tester (manufactured by TA Instruments Japan Co., ltd., model name "ARES"), and the temperature corresponding to the peak top temperature of tan. Delta. Was defined as Tg of the homopolymer.
The weight average molecular weight (Mw) of the polymer (A) is generally suitably about 20X 10 4 The above is not particularly limited. With the polymer (a) of this Mw, an adhesive exhibiting good cohesion is easily obtained. From the viewpoint of obtaining higher cohesion, in some preferred modes, the Mw of the polymer (A) may be, for example, 30X 10 4 The above can be 40×10 4 The above can be 50×10 4 The above can be 60×10 4 Above, it may be 80×10 4 The above. In addition, the Mw of the polymer (A) is generally suitably about 500X 10 4 The following is given. Since the polymer (a) having the Mw easily forms an adhesive agent exhibiting moderate fluidity (mobility of polymer chains), it is suitable for realizing a reinforcing film having low adhesion and high adhesion at the initial stage of adhesion. The Mw of the polymer (A) is not excessively high, and is also preferable from the viewpoint of improving the compatibility with the polymer (B). In some preferred embodiments, the Mw of polymer (A) may be, for example, 250X 10 4 Hereinafter, it may be 200X 10 4 Hereinafter, 150×10 is possible 4 Hereinafter, it may be 100X 10 4 Hereinafter, it may be 70X 10 4 The following is given.
In the present specification, mw of the polymer (a) and the polymer (B) described below can be obtained by converting polystyrene by Gel Permeation Chromatography (GPC). More specifically, the Mw can be measured according to the methods and conditions described in the examples below.
As the polymer (A) in the reinforcing film disclosed herein, an acrylic polymer can be preferably used. When an acrylic polymer is used as the polymer (a), good compatibility with the polymer (B) tends to be easily obtained. When the compatibility of the polymer (a) and the polymer (B) is good, the polymer (B) in the adhesive layer can be improved in mobility, which is preferable because it can contribute to a reduction in initial adhesion and an improvement in adhesion after heating. In addition, an acrylic polymer having a high degree of freedom in molecular design is suitable as an adhesive material which can improve the adhesive property, bending recovery property and bending retention force in a balanced manner.
The acrylic polymer may be, for example, a polymer containing 50% by weight or more of monomer units derived from an alkyl (meth) acrylate, that is, a polymer in which 50% by weight or more of the total amount of monomer components (monomer raw materials a) used for producing the acrylic polymer is an alkyl (meth) acrylate. As the alkyl (meth) acrylate, those having 1 to 20 carbon atoms (i.e., C 1-20 Alkyl (meth) acrylates of linear or branched alkyl groups. From the viewpoint of easily obtaining a balance of characteristics, the (meth) acrylic acid C in the monomer raw material A 1-20 The proportion of the alkyl ester may be, for example, 50% by weight or more, or 60% by weight or more. In some preferred modes, the (meth) acrylic acid C in the monomer feed A 1-20 The proportion of the alkyl ester is 70% by weight or more, more preferably 80% by weight or more, still more preferably 85% by weight or more, and particularly preferably 90% by weight or more. By making the following stepsAn acrylic polymer composed of the above monomer can easily provide an adhesive which combines an adhesive force increase with a bending recovery property and a bending retention force in a balanced manner. In addition, the (meth) acrylic acid C in the monomer raw material A 1-20 The proportion of the alkyl ester may be, for example, 99.9% by weight or less, 98% by weight or less, or 95% by weight or less. In some embodiments, the (meth) acrylic acid C in monomer feed A 1-20 The proportion of the alkyl ester may be, for example, 90% by weight or less, 85% by weight or less, or 80% by weight or less.
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, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like.
Of these, at least (meth) acrylic acid C is preferably used 1-18 Alkyl esters, more preferably at least C (meth) acrylic acid 1-14 Alkyl esters. In some embodiments, the acrylic polymer may contain a polymer selected from the group consisting of (meth) acrylic acid C 4-12 Alkyl esters (preferably acrylic acid C 4-10 Alkyl esters, e.g. acrylic acid C 6-10 Alkyl esters) as monomer units. For example, an acrylic polymer containing one or both of n-Butyl Acrylate (BA) and 2-ethylhexyl acrylate (2 EHA) is preferable, and particularly preferableAcrylic polymers containing at least 2EHA are selected.
In some preferred modes, acrylic acid C in monomer feed A for producing acrylic polymer 6-10 Alkyl esters (suitably acrylic acid C 8-9 The proportion of the alkyl ester, typically 2 EHA), is 70 wt% or more, more preferably 80 wt% or more, still more preferably 85 wt% or more, and particularly preferably 90 wt% or more. The acrylic polymer of the monomer composition is particularly suitable for achieving the effects of the techniques disclosed herein. In addition, acrylic acid C in the monomer raw material A 6-10 Alkyl esters (suitably acrylic acid C 8-9 The proportion of the alkyl ester, typically 2 EHA), may be, for example, 99.9 wt% or less, and may be 98 wt% or less or 95 wt% or less from the viewpoints of initial low adhesion, bending recovery, and the like.
Furthermore, in some preferred modes, in the monomer raw material A for producing the acrylic polymer, it is preferable to limit the (meth) acrylic acid C 1-3 Alkyl esters (e.g. C (meth) acrylic acid) 1 Alkyl esters, typically Methyl Methacrylate (MMA)). (meth) acrylic acid C 1-3 Alkyl esters (e.g. C (meth) acrylic acid) 1 Alkyl esters, typically MMA) tend to have a relatively high Tg, and the cohesive properties of adhesives containing acrylic polymers using the above monomer components tend to be high. By limiting (meth) acrylic acid C 1-3 The amount of alkyl ester used can appropriately reduce the cohesive force of the adhesive, and preferably, an elastic modulus (typically, a surface elastic modulus) suitable for both the flexural holding force and the adhesive force increase is achieved. From such a viewpoint, the monomer raw material A contains (meth) acrylic acid C 1-3 Alkyl esters (e.g. C (meth) acrylic acid) 1 The proportion of the alkyl ester, typically MMA) is preferably 8% by weight or less, more preferably 6% by weight or less, still more preferably 3% by weight or less, and still more preferably 1% by weight or less (for example, 0 to 0.3% by weight).
The monomer raw material a may contain an alkyl (meth) acrylate as a main component and may contain other monomers (copolymerizable monomers) capable of copolymerizing with the alkyl (meth) acrylate as needed. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxyl group, a hydroxyl group, a nitrogen atom-containing ring, or the like) can be suitably used. The monomer having a polar group may help to introduce a crosslinking point to the acrylic polymer or to improve the cohesive force of the acrylic polymer. The copolymerizable monomer may be used singly or in combination of two or more.
As non-limiting examples of the copolymerizable monomer, the following monomers may be mentioned.
Hydroxyl-containing monomers: for example, hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate.
Monomers having a nitrogen atom-containing ring: such as N-vinyl-2-pyrrolidone, N-methyl vinyl pyrrolidone, N-vinyl pyridine, N-vinyl piperidone, N-vinyl pyrimidine, N-vinyl piperazine, N-vinyl pyrazine, N-vinyl pyrrole, N-vinyl imidazole, N-vinyl oxazole, N- (meth) acryl-2-pyrrolidone, N- (meth) acryl piperidine, N- (meth) acryl pyrrolidine, N- (meth) acryl morpholine, N-vinyl-3-morpholone, N-vinyl-2-caprolactam, N-vinyl-1, 3-oxazin-2-one, N-vinyl-3, 5-morpholinedione, N-vinyl pyrazole, N-vinyl isoxazole, N-vinyl thiazole, N-vinyl isothiazole, N-vinyl pyridazine, and the like;
Monomers having a succinimide skeleton such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, and N- (meth) acryloyl-8-oxyhexamethylene succinimide;
maleimides such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; a kind of electronic device with high-pressure air-conditioning system
Examples of the amine-based compound include N-methyl-itaconimide, N-ethyl-itaconimide, N-butyl-itaconimide, N-octyl-itaconimide, N-2-ethylhexyl-itaconimide, N-cyclohexyl-itaconimide, and N-month Gui Jiyi-itaconimide.
Carboxyl group-containing monomers: such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and the like.
Acid anhydride group-containing monomer: such as maleic anhydride, itaconic anhydride.
Epoxy group-containing monomers: for example, epoxy group-containing acrylates such as glycidyl (meth) acrylate and 2-ethyl glycidyl (meth) acrylate, allyl glycidyl ether, glycidyl (meth) acrylate, and the like.
Cyano-containing monomers: such as acrylonitrile, methacrylonitrile, and the like.
Isocyanate group-containing monomer: such as 2-isocyanatoethyl (meth) acrylate, and the like.
Amide group-containing monomers: such as (meth) acrylamide; n, N-dialkyl (meth) acrylamides such as N, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-dipropyl (meth) acrylamide, N-diisopropyl (meth) acrylamide, N-di (N-butyl) (meth) acrylamide, N-di (t-butyl) (meth) acrylamide, and the like; n-alkyl (meth) acrylamides such as N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-N-butyl (meth) acrylamide; n-vinylcarboxylic acid amides such as N-vinylacetamide; monomers having a hydroxyl group and an amide group, for example, N-hydroxyalkyl (meth) acrylamides such as N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth) acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, N- (4-hydroxybutyl) (meth) acrylamide, and the like; monomers having an alkoxy group and an amide group, for example, N-alkoxyalkyl (meth) acrylamides such as N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide; and N, N-dimethylaminopropyl (meth) acrylamide, and the like.
Aminoalkyl (meth) acrylates: such as aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, N-diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate.
Alkoxy-containing monomers: for example, alkoxyalkyl (meth) acrylates such as 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate, and the like; alkoxy alkylene glycol (meth) acrylates such as methoxy ethylene glycol (meth) acrylate and methoxy polypropylene glycol (meth) acrylate.
Monomers containing sulfonic or phosphoric groups: such as styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonate, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, acryloxynaphthalene sulfonic acid, 2-hydroxyethyl acryl phosphate, and the like.
(meth) acrylic acid ester having alicyclic hydrocarbon group: for example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and the like.
(meth) acrylic acid esters having an aromatic hydrocarbon group: for example, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, and the like.
Vinyl ethers: such as vinyl alkyl ethers, e.g., methyl vinyl ether and ethyl vinyl ether.
Vinyl esters: such as vinyl acetate, vinyl propionate, and the like.
Aromatic vinyl compound: such as styrene, alpha-methylstyrene, vinyltoluene, and the like.
Olefins: such as ethylene, butadiene, isoprene, isobutylene, etc.
And heterocyclic (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing (meth) acrylates such as vinyl chloride or fluorine atom-containing (meth) acrylates, silicon atom-containing (meth) acrylates such as silicone (meth) acrylates, and (meth) acrylates obtained from terpene compound derivative alcohols.
When such a copolymerizable monomer is used, the amount thereof is not particularly limited, and is usually preferably 0.01% by weight or more of the monomer raw material A. The amount of the copolymerizable monomer used may be 0.1% by weight or more, or 1% by weight or more of the monomer raw material a, from the viewpoint of more preferably exhibiting the effect caused by the use of the copolymerizable monomer. In some preferred embodiments, the content of the copolymerizable monomer in the monomer raw material a is 3% by weight or more, more preferably 5% by weight or more, still more preferably 7% by weight or more (for example, 8% by weight or more). The more the amount of the copolymerizable monomer used, the higher the cohesiveness and the higher the bending recovery tend to be. The amount of the copolymerizable monomer used may be 50% by weight or less, preferably 30% by weight or less, of the monomer raw material a. This prevents the cohesive force of the adhesive from becoming too high, and improves the tacky feel at normal temperature (25 ℃). In some preferred embodiments, the amount of the copolymerizable monomer used is 20% by weight or less, more preferably 15% by weight or less (for example, 12% by weight or less), and may be 10% by weight or less of the monomer raw material a. By limiting the amount of the copolymerizable monomer used, the cohesive force of the adhesive is reduced, the elastic modulus (typically, the surface elastic modulus) becomes a suitable range, excellent bending retention is easily obtained, and an increase in adhesive force is easily achieved.
In some embodiments, monomer feed a may comprise a monomer having a nitrogen atom-containing ring. By using a monomer having a nitrogen atom-containing ring, the cohesive force and polarity of the adhesive can be adjusted, and the adhesive force after heating can be suitably improved. By including a monomer having a nitrogen atom-containing ring in the monomer raw material a, the compatibility between the polymer (a) formed from the monomer raw material a and the polymer (B) tends to be improved. Thus, a reinforcing film having a greatly improved adhesive strength by heating can be easily obtained.
The monomer having a nitrogen atom-containing ring may be appropriately selected from the above-exemplified monomers, and used singly or in combination of two or more. In some embodiments, the monomer raw material a preferably contains at least one monomer selected from the group consisting of an N-vinyl cyclic amide and a cyclic amide having a (meth) acryloyl group as a monomer having a nitrogen atom-containing ring.
Specific examples of the N-vinyl cyclic amide include: n-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1, 3-oxazin-2-one, N-vinyl-3, 5-morpholindione, and the like. N-vinyl-2-pyrrolidone, N-vinyl-2-caprolactam are particularly preferred.
Specific examples of the cyclic amide having a (meth) acryloyl group include: n- (meth) acryl-2-pyrrolidone, N- (meth) acryl piperidine, N- (meth) acryl pyrrolidine, N- (meth) acryl morpholine, and the like. As a preferred example, N-Acryloylmorpholine (ACMO) is mentioned.
The amount of the monomer having a nitrogen atom-containing ring is not particularly limited, and is usually preferably 40% by weight or less, 30% by weight or less, 20% by weight or less, or 10% by weight or less of the monomer raw material a. In some preferred embodiments, the content of the monomer having a nitrogen atom-containing ring in the monomer raw material a is 7 wt% or less, more preferably 5 wt% or less, and still more preferably 3 wt% or less (for example, 1.5 wt% or less) from the viewpoint of reducing the cohesive force and reducing the elastic modulus (typically the surface elastic modulus). The amount of the monomer having a nitrogen atom-containing ring to be used is usually preferably 0.01% by weight or more (preferably 0.1% by weight or more, for example, 0.5% by weight or more) of the monomer raw material a. From the viewpoint of obtaining a proper cohesive force and elastic modulus, the amount of the monomer having a nitrogen atom-containing ring may be 0.8% by weight or more, or 1.0% by weight or more of the monomer raw material a.
In some preferred embodiments, monomer feed a comprises a hydroxyl-containing monomer. The cohesive force, polarity, and thus elastic modulus (typically surface elastic modulus) of the adhesive can be adjusted by using the hydroxyl-containing monomer, preferably to achieve the effects of the techniques disclosed herein. In addition, the hydroxyl group-containing monomer provides a reaction point with a crosslinking agent (for example, an isocyanate-based crosslinking agent) described below, and the cohesive force of the adhesive can be improved by the crosslinking reaction.
As the hydroxyl group-containing monomer, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, N- (2-hydroxyethyl) (meth) acrylamide, and the like can be suitably used. Among them, preferred examples include 2-hydroxyethyl acrylate (HEA), 4-hydroxybutyl acrylate (4 HBA), and N- (2-hydroxyethyl) acrylamide (HEAA). From the viewpoint of obtaining cohesive force suitable for bend recovery and bend retention, 4HBA is particularly preferred.
The amount of the hydroxyl group-containing monomer used is not particularly limited, and is usually preferably 40% by weight or less, and may be 30% by weight or less, or may be 20% by weight or less of the monomer raw material a. In some preferred embodiments, the content of the hydroxyl group-containing monomer in the monomer raw material a is 15 wt% or less, more preferably 12 wt% or less (for example, 10 wt% or less) from the viewpoint of reducing the cohesive force and further the elastic modulus (typically, surface elastic modulus). By limiting the amount of the hydroxyl group-containing monomer used, the mobility of the polymer (B) in the adhesive layer is improved, and an increase in adhesive force is easily achieved. In other embodiments, the content of the hydroxyl group-containing monomer may be 5% by weight or less of the monomer raw material a. The amount of the hydroxyl group-containing monomer to be used is preferably 0.01% by weight or more (preferably 0.1% by weight or more, for example, 0.5% by weight or more) of the monomer raw material a. From the viewpoint of obtaining moderate cohesive force and elastic modulus, in some preferred embodiments, the amount of the hydroxyl group-containing monomer used is 1% by weight or more, more preferably 3% by weight or more, still more preferably 5% by weight or more, and particularly preferably 7% by weight or more (e.g., 8% by weight or more) of the monomer raw material a.
In some embodiments, as the copolymerizable monomer, a monomer having a nitrogen atom-containing ring and a hydroxyl group-containing monomer may be used in combination. In this case, the total amount of the monomer having a nitrogen atom-containing ring and the hydroxyl group-containing monomer may be, for example, 0.1% by weight or more, preferably 1% by weight or more, more preferably 3% by weight or more, still more preferably 5% by weight or more, particularly preferably 7% by weight or more (for example, 9% by weight or more), 10% by weight or more, 15% by weight or more, 20% by weight or more, or 25% by weight or more of the monomer raw material a. The total amount of the monomer having a nitrogen atom-containing ring and the hydroxyl group-containing monomer may be, for example, 50% by weight or less, preferably 30% by weight or less of the monomer raw material a. In some preferred embodiments, the total amount of the monomer having a nitrogen atom-containing ring and the hydroxyl group-containing monomer is 20% by weight or less, more preferably 15% by weight or less (e.g., 12% by weight or less) of the monomer raw material a.
In the mode of combining the monomer having a ring having a nitrogen atom with the hydroxyl group-containing monomer in the monomer raw material A, the content (W N ) With the content of hydroxyl-containing monomers (W) OH ) The relation (weight basis) of (a) is not particularly limited. W (W) N /W OH For example, it may be 0.01 or more, and usually preferably 0.05 or more, and it may be 0.10 or more, and also 0.12 or more. In addition, W N /W OH For example, it may be 10 or less, preferably 1 or less, preferably 0.50 or less, may be 0.30 or less, may be 0.20 or less, or may be 0.15 or less.
In some embodiments, the monomer raw material a preferably contains no monomer having a polyorganosiloxane skeleton (monomer S1) that can be preferably used as a constituent of the monomer raw material B described below, or the content of the monomer is less than 10 wt% (more preferably less than 5 wt%, for example less than 2 wt%) of the monomer raw material a. By using the monomer material a having such a composition, a reinforcing film having excellent both of the initial reworkability and the strong adhesion after the increase of the adhesive force can be suitably obtained. For the same reason, in other embodiments, the monomer raw material a preferably contains no monomer S1, or in the case of containing the monomer S1, its content (weight basis) is lower than the content of the monomer S1 in the monomer raw material B.
The method for obtaining the polymer a is not particularly limited, and various polymerization methods such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, and a photopolymerization method can be suitably employed. In some embodiments, solution polymerization may be preferred. The polymerization temperature in the solution polymerization may be appropriately selected depending on the types of monomers and solvents used, the types of polymerization initiators, and the like, and may be, for example, about 20 to 170 ℃ (typically about 40 to 140 ℃).
The initiator for polymerization may be appropriately selected from conventionally known thermal polymerization initiators, photopolymerization initiators, and the like according to the polymerization method. The polymerization initiator may be used singly or in combination of two or more.
Examples of the thermal polymerization initiator include azo-based polymerization initiators (for example, 2,2' -azobisisobutyronitrile, 2' -azobis-2-methylbutyronitrile, dimethyl 2,2' -azobis (2-methylpropionate), 4' -azobis-4-cyanovaleric acid, azobisisovaleronitrile 2,2' -azobis (2-amidinopropane) dihydrochloride, 2' -azobis [2- (5-methyl-2-imidazolin-2-yl) propane ] dihydrochloride, 2' -azobis (2-methylpropionamidine) disulfate, 2' -azobis (N, N ' -dimethylene isobutyl amidine) dihydrochloride, etc.); persulfates such as potassium persulfate; peroxide-based polymerization initiators (e.g., dibenzoyl peroxide, t-butyl peroxymaleate, lauroyl peroxide, etc.); redox-type polymerization initiators, and the like. The amount of the thermal polymerization initiator to be used is not particularly limited, and may be, for example, in the range of 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the monomer component (monomer raw material a) used in the production of the polymer (a).
The photopolymerization initiator is not particularly limited, and for example, a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α -ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzil-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, and the like can be used. The amount of the photopolymerization initiator used is not particularly limited, and may be, for example, in the range of 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the monomer raw material a.
In some embodiments, the polymer a may be included in an adhesive composition for forming an adhesive layer in the form of a partial polymer (polymer slurry) obtained by polymerizing a part of the monomer component by irradiating Ultraviolet (UV) to a mixture obtained by compounding the polymerization initiator in the monomer raw material a described above. The polymerization can be completed by applying the adhesive composition containing the polymer slurry to a predetermined object to be coated and irradiating ultraviolet rays. That is, the above polymer slurry can be understood as a precursor of the polymer a. The adhesive layer disclosed herein can be formed, for example, using an adhesive composition containing the above-described polymer slurry and polymer B.
(Polymer (B))
The polymer (B) in the technology disclosed herein is a polymer containing a monomer component (monomer raw material B) of a monomer having a polyorganosiloxane skeleton (hereinafter also referred to as "monomer S1") and a (meth) acrylic monomer. The polymer (B) may be referred to as a copolymer of the monomer S1 and a (meth) acrylic monomer. The polymer (B) may be used singly or in combination of two or more. The polymer (B) can function as an adhesive force increase retarder that suppresses initial adhesive force to an adherend and increases adhesive force to the adherend by heating, due to the low polarity and mobility of the polyorganosiloxane structure derived from the monomer S1. The monomer S1 is not particularly limited, and any monomer containing a polyorganosiloxane skeleton may be used. The monomer S1 promotes the polymer (B) to be present on the surface of the pressure-sensitive adhesive layer in a bias state in the reinforcing film before use (before application to an adherend) due to the low polarity derived from the structure thereof, and exhibits light peelability (low adhesion) at the initial stage of application. As the monomer S1, a monomer having a structure with a polymerizable reactive group at one end can be preferably used. By the constitution including such a monomer S1 unit and a (meth) acrylic monomer unit, a polymer (B) having a polyorganosiloxane skeleton in a side chain is formed. The polymer (B) having such a structure is easily a polymer having low initial adhesion and high adhesion after heating due to the mobility and ease of movement of the side chains. In addition, in some embodiments, as the monomer S1, a monomer having a polymerizable reactive group at one end and having no functional group which causes a crosslinking reaction with the polymer (a) at the other end may be preferably used. The polymer (B) obtained by copolymerizing the monomer S1 having such a structure is easily a polymer having low initial adhesion and high adhesion after heating due to the mobility of the polyorganosiloxane structure derived from the monomer S1.
As the monomer S1, for example, a compound represented by the following general formula (1) or (2) can be used. More specifically, examples of the single-terminal reactive silicone oil manufactured by Xinyue chemical industry Co., ltd include X-22-174ASX, X-22-2426, X-22-2475, KF-2012, and the like. The monomer S1 may be used singly or in combination of two or more.
Figure BDA0004113439390000221
Figure BDA0004113439390000222
Here, R in the above general formulae (1) and (2) 3 Is hydrogen or methyl, R 4 Is methyl or 1-valent organic group, m and n are integers of 0 or more.
The functional group equivalent of the monomer S1 may take an appropriate value within a range where the desired effect is exhibited by using the monomer S1, and is not limited to a specific range. The functional group equivalent is, for example, 100g/mol or more, or 200g/mol or more, preferably 300g/mol or more (for example, 500g/mol or more), preferably 800g/mol or more, and more preferably 1500g/mol or more, from the viewpoint of sufficiently suppressing the initial adhesion. In a particularly preferred embodiment, the functional group equivalent is 2000g/mol or more, more particularly preferably 2500g/mol or more, and may be 3000g/mol or more, 4000g/mol or more, or 5000g/mol or more, from the viewpoint of both low adhesion at the initial stage of attachment and an increase in adhesive force after heating. In other embodiments, the functional group equivalent may be 9000g/mol or more, 12000g/mol or more, or 15000g/mol or more. The functional group equivalent of the monomer S1 refers to a polymerizable functional group (for example, an ethylenically unsaturated group such as a (meth) acryloyl group, a vinyl group, or an allyl group).
From the viewpoint of sufficiently improving the adhesive force, the functional group equivalent is, for example, preferably 30000g/mol or less, 20000g/mol or less, or 15000g/mol or 10000g/mol or less. In some preferred embodiments, the functional group equivalent of the monomer S1 is 7000g/mol or less, more preferably 5500g/mol or less, still more preferably 4500g/mol or less, and may be 4200g/mol or less, or 3500g/mol or less. When the functional group equivalent of the monomer S1 is within the above range, the compatibility in the adhesive layer (for example, the compatibility with the base polymer) is easily improved, the mobility of the polyorganosiloxane skeleton (chain) of the polymer (B) is improved, the mobility of the polymer (B) is easily adjusted to an appropriate range, and an adhesive layer having both low initial adhesion and improved adhesive force after heating can be easily realized.
Herein, "functional group equivalent" refers to the weight of the backbone (e.g., polydimethylsiloxane) bonded to an average of 1 functional group. The labeling unit g/mol is 1mol in terms of functional group. The functional equivalent of the monomer S1 can be determined, for example, by Nuclear Magnetic Resonance (NMR) based 1 The spectrum intensity of H-NMR (proton NMR) was calculated. Based on 1 The functional group equivalent (g/mol) of the monomer S1 of the spectrum intensity of H-NMR can be calculated from 1 A general structure analysis method for H-NMR spectrum analysis is described in Japanese patent No. 5951153, if necessary.
In the case where two or more monomers having different functional group equivalents are used as the monomer S1, an arithmetic average value may be used as the functional group equivalent of the monomer S1. Namely, the monomer comprises n monomers (monomer S1 1 Monomer S1 2 … … monomer S1 n ) The functional group equivalent of the monomer S1 of (2) can be calculated by the following formula.
Functional equivalent (g/mol) of monomer S1= (monomer S1) 1 Functional equivalent of (2) x monomer S1 1 Compounding amount of (C) and monomer S1 2 Functional equivalent of (2) x monomer S1 2 Compounded amount of + … … +monomer S1 n Functional equivalent of (2) x monomer S1 n Compounding amount of (a)/(monomer S1) 1 Compounding amount of (C) and monomer S1 2 Compounded amount of + … … +monomer S1 n Is a compound amount of (a)
The content of the monomer S1 may take an appropriate value within a range where the desired effect is exhibited by using the monomer S1, and is not limited to a specific range. In some embodiments, the content of the monomer S1 in the total amount of the monomer components (monomer raw materials B) used for preparing the polymer (B) may be, for example, 5% by weight or more, preferably 10% by weight or more, more preferably 12% by weight or more, still more preferably 15% by weight or more, particularly preferably 18% by weight or more, and may be 20% by weight or more, from the viewpoint of sufficiently suppressing the initial adhesion. The content of the monomer S1 in the monomer raw material B may be, for example, 80% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less, still more preferably 40% by weight or less, and still more preferably 30% by weight or less, from the viewpoints of polymerization reactivity and compatibility. By setting the polymerization ratio of the monomer S1 to an appropriate range, the increase in adhesive force can be suitably exhibited.
The monomer raw material B contains a (meth) acrylic monomer copolymerizable with the monomer S1 in addition to the monomer S1. The mobility of the polymer (B) in the adhesive layer can be suitably adjusted by using one or two or more (meth) acrylic monomers. In addition, it can also contribute to improving the compatibility of the polymer (B) with the polymer (A). Since the polymer (B) containing a (meth) acrylic monomer unit is well compatible with an acrylic polymer, it is easy to achieve a decrease in initial adhesion and an increase in adhesion after heating by improving the mobility of the polymer (B) in the adhesive layer.
In the polymer (B) used in the technology disclosed herein, the composition of the (meth) acrylic monomer contained in the monomer raw material B may be at the glass transition temperature T of the polymer (B) B Is suitably set in a range of-20 to 5 ℃. Glass transition temperature T based on the composition of the (meth) acrylic monomer B1 Can also satisfy the T B The range of (2) is not limited to a specific range. Typically T B1 For example, it may be set to be higher than 0 ℃. Here, the composition based on (meth) acrylic monomersGlass transition temperature T of (2) B1 Refers to Tg obtained by Fox formula based on the composition of the (meth) acrylic monomer alone in the monomer component used to prepare polymer (B). T (T) B1 The above Fox formula can be applied only to the (meth) acrylic monomer in the monomer component used for producing the polymer (B), and is calculated from the glass transition temperature of the homopolymer of each (meth) acrylic monomer and the weight fraction of each (meth) acrylic monomer in the total amount of the (meth) acrylic monomers. By the glass transition temperature T B1 Relatively high (typically above 0 ℃) polymers (B) tend to inhibit initial adhesion. Furthermore, by the glass transition temperature T B1 Relatively high (typically above 0 ℃) polymers (B) tend to give films for reinforcement with a large increase in adhesion.
In some preferred modes, T B1 The temperature is 10℃or higher, more preferably 30℃or higher, still more preferably 40℃or higher, and may be 45℃or higher. If T B1 The adhesive force at the initial stage of the adhesion tends to be more suppressed in general. The reason for this is thought to be that by T B1 In the polymer (B) having a predetermined temperature or higher, the improvement in the mobility and the mobility of the polyorganosiloxane structural unit due to the temperature rise to room temperature or a high temperature region higher than the room temperature to some extent is effectively suppressed by the monomer unit derived from the (meth) acrylic monomer contained in the polymer (B), and the low adhesiveness due to the presence of the polyorganosiloxane structural unit can be maintained more favorably. From the standpoint of better stability to maintain low adhesion at the initial stage of attachment, in some embodiments, T B1 For example, the temperature may be 50℃or higher, 55℃or higher, or 60℃or higher. In addition, T B1 For example, the temperature may be 120℃or lower, or 100℃or lower. If T B1 The adhesive force tends to be easily increased by heating when the adhesive force is lowered. In some preferred modes, T B1 For example, the temperature is 90℃or lower, more preferably 70℃or lower, still more preferably 60℃or lower, and particularly preferably 55℃or lower (for example, 50℃or lower).
From the easy to exert by properly setting T B1 The resulting effectFrom the viewpoint of the effect, the ratio of the total amount of the monomers S1 and the (meth) acrylic monomer to the total monomer components for producing the polymer (B) may be, for example, 50% by weight or more, 70% by weight or more, 85% by weight or more, 90% by weight or more, 95% by weight or more, or substantially 100% by weight.
Glass transition temperature T of Polymer (B) used in the technology disclosed herein B In the range of-20 ℃ to 5 ℃. By reacting the T of the polymer (B) B At 5℃or lower, the mobility (typically, temperature-sensitive mobility) of the polymer (B) is improved, and the adhesive strength can be greatly increased. In some preferred modes, T of Polymer (B) B The temperature may be less than 0deg.C, below-5deg.C, or below-10deg.C. Further, by letting T B When the temperature is not less than-20 ℃, the polymer (B) which is present on the surface side of the pressure-sensitive adhesive layer in a biased state when the pressure-sensitive adhesive is applied to an adherend tends to lower the initial adhesive force, and the pressure-sensitive adhesive tends to be excellent in light releasability in the initial stage of application. In some preferred modes, T of Polymer (B) B Can be at least-15deg.C. By combining T B The preferable range is set so that the light releasability at the initial stage of application and the increase in adhesive force after heating can be controlled to the preferable range.
In some embodiments, the monomer component used to prepare polymer (B) may be of a composition T B1 Above T B Mode of (i.e.T) B1 -T B Setting the temperature to be higher than 0 ℃. With such a composition, the effect of adjusting the mobility of the polymer (B) by using the composition of the (meth) acrylic monomer contained in the monomer component can be easily and suitably exhibited. T (T) B1 -T B For example, the temperature may be about 40℃to 100℃or about 50℃to 90 ℃. In some preferred modes, T B1 -T B The temperature is 45℃or higher, more preferably 50℃or higher, still more preferably 55℃or higher (for example, 58℃or higher). In addition, from the viewpoint of suitably exhibiting the effect of containing the polymer (B), T B1 -T B Preferably 80℃or lower, more preferably 70℃or lower, and still more preferably 65℃or lower (e.g., 62℃or lower).
From easy control of the migration of the polymer (B) within the adhesive layerFrom the viewpoint of fluidity, in some modes, the composition of the monomer component used for preparing the polymer (B) may be the same as the glass transition temperature T of the polymer (A) A Relation of T B Ratio T A By more than 20℃, i.e. T B -T A Is set to 20 ℃ or higher. In some preferred modes, T B -T A For example, the temperature is 30℃or higher, more preferably 40℃or higher, still more preferably 50℃or higher, and may be 60℃or higher, or 70℃or higher. Further, from the viewpoint of the increase of the adhesive force, T B -T A For example, the temperature may be 130℃or lower, 120℃or lower, preferably 100℃or lower, more preferably 80℃or lower, still more preferably 65℃or lower, 55℃or lower, or 45℃or lower.
Examples of the (meth) acrylic monomer that can be used as the monomer raw material B include alkyl (meth) acrylates. The term "alkyl" as used herein refers to a chain (including straight-chain and branched) alkyl (group) and excludes alicyclic hydrocarbon groups described below. For example, one or two or more of the monomers exemplified above as alkyl (meth) acrylates which can be used for the polymer (a) can be used as constituent components of the monomer raw material B. In some preferred embodiments, monomer feed B may contain (meth) acrylic acid C 4-12 Alkyl esters (preferably C (meth) acrylic acid) 4-10 Alkyl esters, e.g. C (meth) acrylic acid 6-10 Alkyl esters). In other embodiments, monomer feed B may contain methacrylic acid C 1-18 Alkyl esters (preferably methacrylic acid C 1-14 Alkyl esters, e.g. methacrylic acid C 1-10 Alkyl esters). The monomer raw material B may contain, for example, one or two or more selected from MMA, n-butyl methacrylate (nBMA) and 2-ethylhexyl methacrylate (2 EHMA) as the (meth) acrylic monomer.
As another example of the (meth) acrylic monomer, a (meth) acrylate having an alicyclic hydrocarbon group is given. For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 1-adamantyl (meth) acrylate, and the like can be used. In some embodiments, the monomer raw material B may contain at least one selected from the group consisting of dicyclopentanyl methacrylate, isobornyl methacrylate, and cyclohexyl methacrylate as the (meth) acrylic monomer.
The content of the alkyl (meth) acrylate and the alicyclic hydrocarbon group-containing (meth) acrylate in the monomer raw material B may 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. The use of the alkyl (meth) acrylate is advantageous from the viewpoint of easiness of rising of the adhesive force by heating. In some embodiments, the content of the (meth) acrylate having an alicyclic hydrocarbon group may be less than 50 wt% of the monomer raw material B, may be less than 30 wt%, may be less than 15 wt%, may be less than 10 wt%, or may be less than 5 wt%. (meth) acrylic esters having alicyclic hydrocarbon groups may not be used.
In some preferred embodiments, the (meth) acrylic monomer as a constituent of the monomer raw material B may contain a monomer M2 having a homopolymer Tg of 50 ℃ or higher. In the polymer (B), by copolymerizing the monomer S1 and the monomer M2, it is easy to suitably control the mobility and mobility of the polyorganosiloxane structural part accompanying the temperature increase, and at the same time, it is possible to achieve an initial light releasability (reworkability) and an increase in adhesive force after heating. In some embodiments, the homopolymer of monomer M2 may have a Tg of 60 ℃ or higher, may be 70 ℃ or higher, may be 80 ℃ or higher, or may be 90 ℃ or higher. The upper limit of Tg of the homopolymer of the monomer M2 is not particularly limited, but is usually preferably 200 ℃ or lower from the viewpoint of ease of synthesis of the polymer (B). In some embodiments, the homopolymer of monomer M2 may have a Tg of, for example, 180℃or less, 150℃or less, or 120℃or less.
As the monomer M2, for example, a monomer satisfying the condition of Tg of a homopolymer among the above-exemplified (meth) acrylic monomers can be used. For example, one or two or more monomers selected from the group consisting of alkyl (meth) acrylates and (meth) acrylates having alicyclic hydrocarbon groups can be used. As the alkyl (meth) acrylate, an alkyl methacrylate in which the carbon number of the alkyl group is in the range of 1 to 4 can be preferably used.
In the case where the monomer material B contains the monomer M2, the content of the monomer M2 may be, for example, 5 wt% or more, 10 wt% or more, 15 wt% or more, 20 wt% or more, 25 wt% or more, or 30 wt% or more of the monomer material B. In some embodiments, the content of the monomer M2 may be 35 wt% or more, 40 wt% or more, 45 wt% or more, 50 wt% or more, or 55 wt% or more of the monomer raw material B. The content of the monomer M2 may be, for example, 90% by weight or less, and is usually preferably 80% by weight or less, more 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 embodiments, the content of monomer M2 is 60 wt% or less (e.g., 50 wt% or less, typically 42 wt% or less). In the polymer (B), by limiting the copolymerization ratio of the monomer M2 having a Tg of 50 ℃ or higher to a predetermined value or less, it is possible to preferably achieve an increase in adhesive force after heating based on the mobility of the polymer (B) in the vicinity of 50 ℃. From the same viewpoint, the content of the monomer M2 in the monomer raw material B may be 35% by weight or less, 25% by weight or less, or 15% by weight or less (for example, 5% by weight or less).
The content of the monomer M2 described above can be preferably applied, for example, to the following modes: the monomer M2 includes one or two or more monomers selected from the group consisting of alkyl (meth) acrylates and (meth) acrylates having alicyclic hydrocarbon groups, and the monomer M2 includes one or two or more monomers selected from the group consisting of alkyl (meth) acrylates (e.g., alkyl methacrylates). As a preferable example of this embodiment, an embodiment in which the monomer M2 contains MMA is given.
In some embodiments, the (meth) acrylic monomer may also comprise a monomer M3 having a homopolymer Tg of less than 50 ℃ (typically greater than-20 ℃ and less than 50 ℃). By using the monomer M3, a reinforcing film which gives a balanced balance between adhesive force and cohesive force after the adhesive force has been increased can be easily obtained. From the viewpoint of easily exhibiting this effect, the monomer M3 is preferably used in combination with the monomer M2.
As the monomer M3, for example, a monomer satisfying the condition of Tg of a homopolymer among the (meth) acrylic monomers exemplified above can be used. For example, one or two or more monomers selected from the group consisting of alkyl (meth) acrylates may be used.
In the embodiment in which the monomer material B contains the monomer M3, the content of the monomer M3 may be, for example, 5 wt% or more, 10 wt% or more, 15 wt% or more, 20 wt% or more, 25 wt% or more, 30 wt% or more, or 35 wt% or more of the monomer material B. The content of the monomer M3 is usually preferably 70% by weight or less, but may be 60% by weight or less, or 50% by weight or less of the monomer raw material B. The content of the above-mentioned monomer M3 may be preferably applied, for example, to a manner in which the monomer M3 contains one or two or more monomers selected from alkyl (meth) acrylates (e.g., alkyl methacrylates).
In some embodiments of the reinforcement films disclosed herein, the monomer feed B preferably has a homopolymer monomer content of less than 30% by weight with a Tg greater than 170 ℃. Here, unless otherwise specified, the term "the content of the monomer is X% by weight or less" in this specification means that the term "the content of the monomer is 0% by weight", that is, the term "the monomer is not substantially contained". In addition, substantially free means that at least the above monomers are not used intentionally. If the copolymerization ratio of the monomer having Tg of the homopolymer of more than 170 ℃ is high, the mobility of the polymer (B) tends to be insufficient, and it may be difficult to increase the adhesive strength by heating to a temperature range of more than 50 ℃.
In some embodiments, monomer feed B preferably comprises at least MMA as the (meth) acrylic monomer. By copolymerizing the polymer (B) with MMA, a reinforcing film having a high adhesive force after heating can be easily obtained. The ratio of MMA to the total amount of the (meth) acrylic monomers contained in the monomer raw material B may 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. In addition, the proportion of MMA in the total amount of the monomer raw materials B is usually preferably 95% by weight or less, and in some preferred embodiments, from the viewpoint of an increase in adhesive force after heating, the proportion of MMA in the total amount of the monomer raw materials B may be 75% by weight or less, 65% by weight or less, 60% by weight or less, or 55% by weight or less (for example, 50% by weight or less).
As another example of the monomer which can be contained together with the monomer S1 as the monomer unit constituting the polymer (B), there can be mentioned: examples of the monomers usable for the polymer (A) include carboxyl group-containing monomers, anhydride group-containing monomers, hydroxyl group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, isocyanate group-containing monomers, amide group-containing monomers, nitrogen atom ring-containing monomers (N-vinyl cyclic amides, cyclic amides having (meth) acryloyl groups, monomers having a maleimide skeleton, maleimides, itaconimides, and the like), (meth) acrylic acid aminoalkyl esters, vinyl ethers, olefins, aromatic hydrocarbon group-containing (meth) acrylates, heterocyclic ring-containing (meth) acrylates, halogen atom-containing (meth) acrylates, and (meth) acrylates obtained from terpene compound derivative alcohols.
As still another example of the monomer which can be contained together with the monomer S1 as the monomer unit constituting the polymer (B), there can be mentioned: oxyalkylene di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, and the like; monomers having a polyoxyalkylene skeleton, for example, polymerizable polyoxyalkylene ethers having a (meth) acryloyl group, vinyl group, allyl group and other polymerizable functional groups at one end of a polyoxyalkylene chain such as polyethylene glycol and polypropylene glycol, and having an ether structure (alkyl ether, aryl ether, arylalkyl ether and the like) at the other end; alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate, and the like; alkali metal (meth) acrylate salts; a polyvalent (meth) acrylate such as trimethylolpropane tri (meth) acrylate: halogenated vinyl compounds such as vinylidene chloride and 2-chloroethyl (meth) acrylate; oxazolinyl group-containing monomers such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-isopropenyl-2-oxazoline; aziridinyl (meth) acryl aziridine, aziridinyl-2-aziridinylethyl (meth) acrylate and other aziridinyl-containing monomers; hydroxy-containing vinyl monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and adducts of lactones and 2-hydroxyethyl (meth) acrylate; fluorine-substituted vinyl-containing monomers such as alkyl (meth) acrylates; reactive halogen-containing vinyl monomers such as 2-chloroethyl vinyl ether and vinyl monochloroacetate; organosilicon-containing vinyl monomers such as vinyl trimethoxysilane, γ - (meth) acryloxypropyl trimethoxysilane, allyl trimethoxysilane, trimethoxysilylpropyl allylamine, and 2-methoxyethoxy trimethoxysilane; and macromers having a radically polymerizable vinyl group at the end of a monomer having a vinyl group polymerized therein. These may be copolymerized with the monomer S1 singly or in combination of two or more.
In some embodiments, as the polymer (B), a polymer having no functional group which causes a crosslinking reaction with the polymer (a) may be preferably used. In other words, the polymer (B) is preferably contained in the adhesive layer in a form not to be chemically bonded to the polymer (a). The adhesive layer containing the polymer (B) in such a form is excellent in the mobility of the polymer (B) when heated, and is suitable for improving the adhesive force increasing ratio. The functional group which reacts with the polymer (a) may vary depending on the kind of functional group which the polymer (a) has, and may be, for example, an epoxy group, an isocyanate group, a carboxyl group, an alkoxysilyl group, an amino group, or the like.
The Mw of the polymer (B) is not particularly limited. The Mw of the polymer (B) may be 1000 or more, or 5000 or more, for example. In some preferred embodiments, the Mw of the polymer (B) is 10,000 or more, more preferably 12,000 or more, and may be 15,000 or more, 20,000 or more, 22,000 or more, or 25,000 or more, from the viewpoint of suitably exhibiting an increase in adhesive force after heating. In other embodiments, the Mw of polymer (B) may be 30,000 or more, may be 50,000 or more, or may be 70,000 or more. The upper limit of Mw of the polymer (B) is, for example, 500,000 or less, 350,000 or less, 200,000 or less, or 150,000 or less. In some preferred embodiments, the Mw of the polymer (B) is 100,000 or less, more preferably 80,000 or less, still 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 further may be 20,000 or less, from the viewpoint of suitably adjusting the compatibility and mobility in the adhesive layer to a proper range and suitably exhibiting low adhesion at the initial stage of attachment. By setting the Mw of the polymer (B) to an appropriate range, an adhesive excellent in both of light peelability and adhesive force rising property at the initial stage of attachment can be easily obtained.
In some preferred embodiments, the Mw of polymer (B) is preferably lower than the Mw of polymer (A). This facilitates the realization of a reinforcing film which combines good reworkability in the initial stage of adhesion and an increase in adhesive force after heating. In some embodiments, the Mw of polymer (B) may be, for example, 0.8 times or less, may be 0.75 times or less, may be 0.5 times or less, or may be 0.3 times or less the Mw of polymer (a). In some preferred embodiments, the Mw of polymer (B) B Mw relative to Polymer (A) A Ratio (Mw) B /Mw A ) The content is 0.3 or less, more preferably 0.2 or less, still more preferably 0.1 or less, and particularly preferably 0.06 or less (e.g., 0.05 or less). In addition, the ratio (Mw B /Mw A ) For example, it is preferably 0.010 or more, more preferably 0.020 or more, still more preferably 0.03 or more, and still more preferably 0.04 or more. By setting the Mw of the polymer (a) and the Mw of the polymer (B) to an appropriate range, the effects of the techniques disclosed herein can be more effectively achieved. In other embodiments, the Mw of polymer (B) may also be less than 0.03 times (e.g., less than 0.02 times) the Mw of polymer (A).
The polymer (B) can be produced by polymerizing the above-mentioned monomer by a known method such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, or a photopolymerization method.
In order to adjust the molecular weight of the polymer (B), a chain transfer agent may be used as needed. Examples of the chain transfer agent used include: mercapto compounds such as octyl mercaptan, lauryl mercaptan, t-nonyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, and α -thioglycerol; thioglycolate esters such as thioglycollic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, ethylene glycol thioglycolate, neopentyl glycol thioglycolate, pentaerythritol thioglycolate, and the like; alpha-methylstyrene dimer, and the like.
The amount of the chain transfer agent used is not particularly limited, but is usually 0.05 to 20 parts by weight, preferably 0.1 to 15 parts by weight, more preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the monomer. By adjusting the addition amount of the chain transfer agent in this manner, a polymer (B) having an appropriate molecular weight can be obtained.
As means for adjusting the molecular weight of the polymer (B), various conventionally known means including the use of the above chain transfer agent may be used alone or in appropriate combination. The same applies to the molecular weight of the polymer (A). Non-limiting examples of such means include selection of a polymerization method, selection of a kind of a polymerization initiator, selection of a used amount, selection of a polymerization temperature, selection of a kind of a polymerization solvent in a solution polymerization method, selection of a used amount, selection of light irradiation intensity in a photopolymerization method, and the like. The person skilled in the art will understand how to obtain a polymer having a desired molecular weight based on the description of the present application specification including the following specific examples and the technical knowledge at the time of the present application.
In the reinforcing film disclosed herein, the amount of the polymer (B) used may be, for example, 0.1 parts by weight or more, preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, still more preferably 1.5 parts by weight or more, or 2 parts by weight or more, based on 100 parts by weight of the amount of the polymer (a) used, from the viewpoint of obtaining a higher effect (suitably light releasability at the initial stage of application). In some embodiments, the amount of the polymer (B) used may be 3 parts by weight or more, 4 parts by weight or more, or 5 parts by weight or more, for example, from the viewpoint of improving reworkability or the like. The amount of the 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, based on 100 parts by weight of the polymer (a) used. From the viewpoint of suitably achieving the target increase in adhesive force, in some preferred embodiments, the amount of the polymer (B) used is 5 parts by weight or less, more preferably 4 parts by weight or less, still more preferably 3 parts by weight or less, and particularly preferably 2.5 parts by weight or less, relative to 100 parts by weight of the polymer (a). In other preferred embodiments, the polymer (B) is used in an amount of 1.5 parts by weight or less (e.g., 1.2 parts by weight or less) relative to 100 parts by weight of the polymer (A). By setting the amount of the polymer (B) to the above range, good bending recovery and bending retention can be easily achieved. Further, the light peelability and the adhesive force rising property at the initial stage of the adhesion can be more favorably combined.
The pressure-sensitive adhesive layer may contain a polymer (any polymer) other than the polymer (a) and the polymer (B) as needed within a range that does not significantly impair the performance of the reinforcing film disclosed herein. The amount of such an optional polymer is usually 20% by weight or less, preferably 15% by weight or less, preferably 10% by weight or less, based on the entire polymer component contained in the pressure-sensitive adhesive layer. In some embodiments, the amount of the optional polymer may be 5 wt% or less, 3 wt% or less, or 1 wt% or less of the entire polymer component. The pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer substantially free of a polymer other than the polymer (A) and the polymer (B).
(crosslinking agent)
In the adhesive layer, a crosslinking agent may be used as needed for the purpose of adjustment of cohesive force or the like. As the crosslinking agent, a crosslinking agent known in the adhesive field can be used, and examples thereof include: epoxy-based crosslinking agents, isocyanate-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, and the like. Isocyanate-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-based crosslinking agents can be suitably used. As a crosslinking agent that suitably combines the bending recovery property and the bending retention force, an isocyanate-based crosslinking agent can be preferably used. The crosslinking agent may be used singly or in combination of two or more.
As the isocyanate-based crosslinking agent, polyfunctional isocyanates (meaning compounds having an average of 2 or more isocyanate groups per 1 molecule, including compounds having an isocyanurate structure) can be preferably used. The isocyanate-based crosslinking agent may be used singly or in combination of two or more.
Examples of the polyfunctional isocyanate include: aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and the like.
Specific examples of aliphatic polyisocyanates include: 1, 2-ethylene diisocyanate; tetramethylene diisocyanate such as 1, 2-tetramethylene diisocyanate, 1, 3-tetramethylene diisocyanate, and 1, 4-tetramethylene diisocyanate; hexamethylene diisocyanate 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, lysine diisocyanate, and the like.
Specific examples of the alicyclic polyisocyanate include: isophorone diisocyanate; cyclohexyl diisocyanate such as 1, 2-cyclohexyl diisocyanate, 1, 3-cyclohexyl diisocyanate, and 1, 4-cyclohexyl diisocyanate; cyclopentyl diisocyanate such as 1, 2-cyclopentyl diisocyanate and 1, 3-cyclopentyl diisocyanate; hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylylene diisocyanate, 4' -dicyclohexylmethane diisocyanate, and the like.
Specific examples of the aromatic polyisocyanate include: 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 4' -diphenylmethane diisocyanate, 2' -diphenylmethane diisocyanate, 4' -diphenyl ether diisocyanate, 2-nitrodiphenyl-4, 4' -diisocyanate, 2' -diphenylpropane-4, 4' -diisocyanate 3,3' -dimethyldiphenylmethane-4, 4' -diisocyanate, 4' -diphenylpropane diisocyanate, isophthaloyl diisocyanate, terephthaloyl diisocyanate, naphthylene-1, 4-diisocyanate, naphthylene-1, 5-diisocyanate, 3' -dimethoxydiphenylmethane-4, 4' -diisocyanate, xylylene-1, 4-diisocyanate, xylylene-1, 3-diisocyanate, and the like.
As the preferable polyfunctional isocyanate, polyfunctional isocyanates having an average of 3 or more isocyanate groups per 1 molecule can be exemplified. The 3-functional or higher isocyanate may be a polymer (e.g., a dimer or trimer) of a 2-functional or higher isocyanate, a derivative (e.g., an addition reaction product of a polyol and a 2-molecule or higher polyfunctional isocyanate), a polymer, or the like. Examples include: dimers, trimers, isocyanurate bodies (isocyanurate structure trimer adducts) of diphenylmethane diisocyanate, reaction products of trimethylolpropane and toluene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, trimethylolpropane adducts of xylylene diisocyanate, trimethylolpropane adducts of isophorone diisocyanate, trimethylolpropane adducts of hexamethylene diisocyanate, polymethylene polyisocyanates, polyether polyisocyanates, polyester polyisocyanates, and polyfunctional isocyanates such as those polyfunctional with isocyanurate linkages, biuret linkages, allophanate linkages, and the like.
Examples of the commercial products of the polyfunctional isocyanate include: trade name "Duranate TPA-100" manufactured by the chemical company of the rising; trade names "Coronate L", "Coronate HL", "Coronate HK", "Coronate HX", "Coronate 2096", manufactured by Tosoh corporation; trade names "Takenate D110N", "Takenate D120N", "Takenate D140N", "Takenate D160N", etc. manufactured by Mitsui chemical company.
Examples of the epoxy-based crosslinking agent include: bisphenol A, epichlorohydrin-based epoxy resins, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerol triglycidyl ether, 1, 6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidylamine, N, N, N ', N' -tetraglycidyl m-xylylenediamine, 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane, and the like. These may be used singly or in combination of two or more.
The metal chelate compound includes aluminum, iron, tin, titanium, nickel, and the like as a metal component, and acetylene, methyl acetoacetate, ethyl lactate, and the like as a chelate component. These may be used singly or in combination of two or more.
The amount of the crosslinking agent used is not particularly limited, and may be, for example, more than 0 parts by weight based on 100 parts by weight of the polymer (A). The amount of the crosslinking agent to be used may be, for example, 0.01 parts by weight or more, and preferably 0.05 parts by weight or more based on 100 parts by weight of the polymer (a). By increasing the amount of the crosslinking agent, the adhesive force at the initial stage of adhesion is suppressed, and the reworkability tends to be improved. The bending recovery property and the workability tend to be excellent. In some embodiments, the crosslinking agent may be used in an amount of 0.1 parts by weight or more, 0.5 parts by weight or more, or 0.8 parts by weight or more, based on 100 parts by weight of the polymer (a). On the other hand, from the viewpoint of appropriately allowing the mobility of the polymer (B) and obtaining an increase in adhesive force after heating, the amount of the crosslinking agent used is usually preferably 15 parts by weight or less, and may be 10 parts by weight or less, or may be 5 parts by weight or less, based on 100 parts by weight of the polymer (a).
The technology disclosed herein can be preferably carried out in such a manner that at least an isocyanate-based crosslinking agent is used as the crosslinking agent. From the viewpoint of both good reworkability at the initial stage of adhesion and an increase in adhesive force after heating, the amount of the isocyanate-based crosslinking agent used may 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, may be 0.10 parts by weight or more, or may be 0.15 parts by weight or more (for example, 0.20 parts by weight or more) based on 100 parts by weight of the polymer (a). By increasing the amount of the isocyanate-based crosslinking agent, proper cohesive force and elastic modulus can be obtained, and bending recovery and processability tend to be excellent. The amount of the isocyanate-based crosslinking agent used may 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, still more preferably less than 0.3 parts by weight, and particularly preferably less than 0.2 parts by weight (for example, 0.15 parts by weight or less) based on 100 parts by weight of the polymer (a). Thus, the cohesive force of the adhesive agent, and thus the elastic modulus (typically, the surface elastic modulus) is moderately reduced, and a good bending retention force can be obtained, and an increase in adhesive force after heating can be easily obtained.
When an isocyanate-based crosslinking agent is used in the structure in which the pressure-sensitive adhesive layer contains a hydroxyl-containing monomer as a monomer unit, the molar ratio ([ NCO ]/[ OH ]) of isocyanate groups to hydroxyl groups contained in the pressure-sensitive adhesive layer may be, for example, 0.001 or more, and is not particularly limited. By increasing the amount of the isocyanate-based crosslinking agent to be used relative to the hydroxyl group-containing monomer in this manner, the elastic modulus (typically the surface elastic modulus) of the adhesive becomes a suitable range, and the bending recovery tends to be improved. In addition, workability tends to be excellent. In some preferred embodiments, the molar ratio ([ NCO ]/[ OH ]) is 0.002 or more, more preferably 0.004 or more, still more preferably 0.006 or more (e.g., 0.007 or more), and may be 0.010 or more, 0.020 or more, or 0.030 or more. The molar ratio ([ NCO ]/[ OH ]) may be, for example, 1.0 or less, or 0.10 or less. By limiting the above molar ratio to a predetermined value or less, a crosslinked structure suitable for greatly increasing the adhesive force after heating with respect to the adhesive force at the initial stage of attachment can be preferably formed. In some preferred embodiments, the molar ratio ([ NCO ]/[ OH ]) is 0.030 or less, more preferably 0.015 or less, even more preferably 0.012 or less (e.g., 0.009 or less), and may be 0.005 or less. In the adhesive layer, isocyanate groups and hydroxyl groups may be present in a state in which at least a part of them is chemically bonded (crosslinked). More specifically, the isocyanate group may be chemically bonded (crosslinked) to the hydroxyl group. On the other hand, the hydroxyl group may be present in a state in which a part thereof is chemically bonded to an isocyanate group and another part thereof is not chemically bonded (crosslinked) to the isocyanate group.
In some preferred forms, the adhesive layer comprises a catalyst. The catalyst may be added for the purpose of promoting the curing of the adhesive layer when forming the adhesive layer, typically for the purpose of making any of the above-described crosslinking reactions more efficiently proceed. Thus, the above catalysts are also referred to as curing catalysts or crosslinking catalysts. By adding the catalyst, initial curing can be promoted, and side reactions that cause bubbles to be generated on the surface of the adhesive layer can be suppressed. The catalyst may be: an organometallic compound such as an iron-based catalyst, a tin-based catalyst, a titanium-based catalyst, a zirconium-based catalyst, a lead-based catalyst, a cobalt-based catalyst, a zinc-based catalyst, or a tertiary amine compound. These may be used singly or in combination of two or more. Among them, iron-based catalysts and tin-based catalysts are preferable from the viewpoint of balance between reaction rate and pot life, and iron-based catalysts are particularly preferable.
Examples of the iron-based catalyst include iron acetylacetonate and iron 2-ethylhexanoate. The iron-based catalyst may be used singly or in combination of two or more.
Examples of the tin catalyst include: dibutyl tin dichloride, dibutyl tin oxide, dibutyl tin dibromide, dibutyl tin maleate, dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin sulfide, tributyl tin methoxide, tributyl tin acetate, triethyl tin ethoxide, tributyl tin ethoxide, dioctyl tin oxide, dioctyl tin dilaurate, tributyl tin chloride, tributyl tin trichloroacetate, tin 2-ethylhexanoate, and the like. The tin catalyst may be used singly or in combination of two or more.
The amount of the catalyst to be used is not particularly limited, but may 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, still more preferably 0.006 parts by weight or more, and particularly preferably 0.008 parts by weight or more, based on 100 parts by weight of the polymer (a). By using an appropriate amount of the catalyst, generation of bubbles in the self-adhesive layer can be suppressed, and a smooth adhesive surface can be easily obtained. The amount of the catalyst to be used may be, for example, 1 part by weight or less or 0.1 part by weight or less based on 100 parts by weight of the polymer (a). In some preferred embodiments, the catalyst is used in an amount of 0.03 parts by weight or less, more preferably 0.02 parts by weight or less, still more preferably 0.01 parts by weight or less, and may be 0.005 parts by weight or less, based on 100 parts by weight of the polymer (a). By appropriately limiting the content of the catalyst relative to 100 parts by weight of the polymer (a), an appropriate increase in adhesive force can be easily achieved.
In the case of using a catalyst in the constitution in which the adhesive layer contains a hydroxyl group-containing monomer as a monomer unit, the amount of the catalyst to be used may be set to the molar ratio of the catalyst contained in the adhesive layer to the hydroxyl group ([ catalyst)]/[OH]) For example 1.0X10 -6 The above amount is preferably 1.0X10 -5 The above is more preferably 1.0X10 -4 The above is more preferably 2.0X10 -4 The above is particularly preferably 3.0X10 -4 The above amounts are not particularly limited. By using an appropriate amount of the catalyst, generation of bubbles in the self-adhesive layer can be suppressed, and a smooth adhesive surface can be easily obtained. In addition, the above molar ratio ([ catalyst)]/[OH]) For example, it may be set to 5.0X10 -2 Hereinafter, the ratio may be 5.0X10 -3 The following is given. In some preferred embodiments, the molar ratio ([ catalyst)]/[OH]) Is 3.0X10 -3 Hereinafter, more preferably 1.0X10 -3 Hereinafter, it is more preferable that the ratio is 5.0X10 -4 Hereinafter, it may be 3.0X10 -4 The following is given. By appropriately limiting the content of the catalyst, an appropriate increase in adhesion can be easily achieved.
(tackifying resin)
The adhesive layer may contain a tackifying resin as needed. The tackifying resin is not particularly limited, and examples thereof include: rosin-based tackifying resins, terpene-based tackifying resins, phenolic-based tackifying resins, hydrocarbon-based tackifying resins, ketone-based tackifying resins, polyamide-based tackifying resins, epoxy-based tackifying resins, elastomeric-based tackifying resins, and the like. The tackifying resin may be used singly or in combination of two or more.
The content of the tackifying resin is not particularly limited, and may be set so as to exhibit an appropriate adhesive property according to the purpose and use. The content of the tackifying resin (in the case of containing two or more tackifying resins, the total amount thereof) may be, for example, about 5 to 500 parts by weight relative to 100 parts by weight of the polymer (a). In addition, the techniques disclosed herein may be preferably practiced in a manner that limits the amount of tackifying resin used. For example, the content of the tackifying resin may be set to less than 20 parts by weight, may be less than 10 parts by weight, may be less than 3 parts by weight, may be less than 1 part by weight (0 parts by weight to less than 1 part by weight) relative to 100 parts by weight of the polymer (a), and in some cases the adhesive layer contains substantially no tackifying resin.
The pressure-sensitive adhesive layer in the technology disclosed herein may contain, if necessary, known additives usable as adhesives such as leveling agents, plasticizers, softeners, colorants (dyes, pigments, etc.), fillers, antistatic agents, antioxidants, ultraviolet absorbers, antioxidants, light stabilizers, and preservatives, within a range that does not significantly hinder the effects of the present invention.
The adhesive layer constituting the reinforcing film disclosed herein may be a cured layer of the adhesive composition. That is, the adhesive layer can be formed by applying (for example, coating) an adhesive composition such as a water-dispersible, solvent-based, photo-curable, or hot-melt type to an appropriate surface, and then suitably performing a curing treatment. In the case of performing two or more kinds of curing treatments (drying, crosslinking, polymerization, cooling, etc.), these may be performed simultaneously or in multiple stages. For the adhesive composition of a part of the polymer (polymer slurry) using the monomer raw material, it is typical to perform the final copolymerization reaction as the above-mentioned curing treatment. That is, a portion of the polymer is subjected to further copolymerization to form a complete polymer. For example, in the case of a photocurable adhesive composition, light irradiation is performed. If necessary, a curing treatment such as crosslinking and drying may be performed. For example, in the case where the composition is a photocurable adhesive composition and drying is required, it is preferable to carry out photocuring after drying. As for the adhesive composition using the complete polymer, typically, the above-mentioned curing treatment is carried out by drying (heat drying), crosslinking, or the like, as necessary.
The adhesive composition may be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a roll lick coater, a dip roll coater, a bar coater, a blade coater, or a spray coater.
The thickness of the pressure-sensitive adhesive layer is not particularly limited, and may be, for example, 6 μm or more. In some embodiments, the thickness of the adhesive layer may be 8 μm or more, may be 10 μm or more, may be 15 μm or more, may be 20 μm or more, or may exceed 20 μm. By increasing the thickness of the adhesive layer, the adhesive force tends to increase after heating. In some embodiments, the thickness of the adhesive layer may be, for example, 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, or 40 μm or less. The thickness of the adhesive layer is not excessively large, and is advantageous from the viewpoints of thinning the reinforcing film, preventing cohesive failure of the adhesive layer, and the like. The reinforcing film having the pressure-sensitive adhesive layer with a thickness within the above range can achieve a balance among adhesive properties such as adhesive force, bending recovery, and bending holding power. In the case of the reinforcing film having the first adhesive layer and the second adhesive layer on the first surface and the second surface of the base material, the thickness of the adhesive layer may be at least suitable for the thickness of the first adhesive layer. The thickness of the second adhesive layer may also be selected from the same range. In the case of the reinforcing film without a base material, the thickness of the reinforcing film is equal to the thickness of the adhesive layer.
< support substrate >)
The reinforcing film of some embodiments may be in the form of a pressure-sensitive adhesive sheet with a base material having a pressure-sensitive adhesive layer on one or both sides of a support base material. The material of the support base is not particularly limited, and may be appropriately selected depending on the purpose, mode of use, and the like of the reinforcing film. As non-limiting examples of substrates that can be used, there can be mentioned: resin films such as plastic films; foam sheets formed of a foam such as polyurethane foam, polyethylene foam, polychloroprene foam, or the like; woven fabrics and nonwoven fabrics obtained by various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semisynthetic fibers such as acetate, etc.) alone or by blending; papers such as japanese paper, high-quality paper, kraft paper, crepe paper, etc.; metal foils such as aluminum foil and copper foil; etc. The substrate may be a composite structure of these. Examples of such a composite substrate include a substrate having a structure in which a metal foil and the plastic film are laminated, a plastic substrate reinforced with inorganic fibers such as glass cloth, and the like.
As the substrate of the reinforcing film disclosed herein, various film substrates can be preferably used. The film substrate may be porous, such as a foam film or a nonwoven fabric sheet, or may be a non-porous substrate, or may be a substrate having a structure in which a porous layer is laminated with a non-porous layer. In some embodiments, as the film base material, a film base material including a resin film (free-standing or independent) capable of independently maintaining a shape as a base film can be preferably used. The term "resin film" as used herein refers to a resin film of a non-porous structure, typically substantially free of bubbles (void-free). Therefore, the resin film is a concept different from a foam film and a nonwoven fabric. As the resin film, a resin film (free-standing or independent) which can maintain its shape independently can be preferably used. The resin film may have a single-layer structure or a multilayer structure (for example, a three-layer structure) having two or more layers.
As the resin material constituting the resin film, for example, polyamide (PA), polyimide (PI), polyamideimide (PAI), polyether ether ketone (PEEK), polyether sulfone (PES), polyphenylene sulfide (PPS), polycarbonate (PC), polyurethane (PU), ethylene-vinyl acetate copolymer (EVA), fluororesin such as Polytetrafluoroethylene (PTFE), acrylic resin, polyacrylate, polystyrene, polyvinyl chloride, polyvinylidene chloride, and the like can be used. The resin film may be formed using a resin material containing one kind of such a resin alone, or may be formed using a resin material obtained by mixing two or more kinds of such resins. The resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched).
Examples of suitable resin materials constituting the resin film include polyimide-based resins, polyester-based resins, PPS resins, and polyolefin-based resins. Here, the polyimide-based resin means a resin containing polyimide in an amount exceeding 50% by weight. Similarly, the polyester resin means a resin containing polyester in an amount of more than 50% by weight, the PPS resin means a resin containing PPS in an amount of more than 50% by weight, and the polyolefin resin means a resin containing polyolefin in an amount of more than 50% by weight.
Specific examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate.
As the polyolefin resin, one polyolefin may be used alone, or two or more polyolefins may be used in combination. The polyolefin may be, for example, a homopolymer of an α -olefin, a copolymer of two or more α -olefins, a copolymer of one or more α -olefins and other vinyl monomers, or the like. Specific examples thereof include ethylene-propylene copolymers such as Polyethylene (PE), polypropylene (PP), poly-1-butene, poly-4-methyl-1-pentene, and ethylene-propylene rubber (EPR), ethylene-propylene-butene copolymers, ethylene-vinyl alcohol copolymers, and ethylene-ethyl acrylate copolymers. Any of Low Density (LD) polyolefin and High Density (HD) polyolefin may be used. Examples of the polyolefin resin film include an unstretched polypropylene (CPP) film, a biaxially oriented polypropylene (OPP) film, a Low Density Polyethylene (LDPE) film, a Linear Low Density Polyethylene (LLDPE) film, a Medium Density Polyethylene (MDPE) film, a High Density Polyethylene (HDPE) film, a Polyethylene (PE) film obtained by mixing two or more Polyethylenes (PE), and a PP/PE mixed film obtained by mixing polypropylene (PP) and Polyethylene (PE).
Specific examples of the resin film that can be preferably used as the base film of the reinforcing film disclosed herein include PI film, PET film, PEN film, PPS film, PEEK film, CPP film, and OPP film.
To the resin film, known additives such as a light stabilizer, an antioxidant, an antistatic agent, a colorant (dye, pigment, etc.), a filler, a slip agent, an antiblocking agent, etc. may be blended as necessary within a range that does not significantly impair the effects of the present invention. The blending amount of the additive is not particularly limited and may be appropriately set according to the purpose or the like.
The method for producing the resin film is not particularly limited. For example, conventionally known general resin film forming methods such as extrusion molding, blow molding, T-die casting, and calender roll molding can be suitably employed.
The substrate may be a substrate consisting essentially of such a base film. Alternatively, the substrate may be a substrate including an auxiliary layer in addition to the base film. Examples of the auxiliary layer include an optical property adjusting layer (e.g., a coloring layer or an antireflection layer), a printed layer for imparting a desired appearance to a substrate, a laminate layer, an antistatic layer, an undercoat layer, and a surface treatment layer such as a release layer.
The thickness of the base material is not particularly limited, and may be selected according to the purpose of use, the mode of use, and the like of the reinforcing film. The thickness of the base material may be 1000 μm or less, for example. In some embodiments, the thickness of the base material may be, for example, 500 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less from the viewpoint of the handleability and workability of the reinforcing film. In some embodiments, the thickness of the base material may be, for example, 160 μm or less, 130 μm or less, 100 μm or less, 90 μm or less, 80 μm or less, 60 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, or 5 μm or less from the viewpoint of downsizing and weight reduction of the product to which the reinforcing film is applied. When the thickness of the base material is reduced, flexibility of the reinforcing film and the following property to the surface shape of the adherend tend to be improved. From the viewpoint of handling properties, processability, etc., the thickness of the substrate may be, for example, 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 25 μm or more, or more than 25 μm. In some embodiments, the thickness of the substrate may be, for example, 30 μm or more, 35 μm or more, 55 μm or more, 70 μm or more, 75 μm or more, 90 μm or more, or 120 μm or more. For example, a substrate having a thickness of 30 μm or more can be preferably used for the reinforcing film.
The first surface of the substrate may be subjected to conventionally known surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and formation of an undercoat layer by application of a primer (primer), as required. Such a surface treatment may be a treatment for improving the anchoring property of the adhesive layer to the substrate. For example, in the case of a reinforcing film including a base material including a resin film as a base film, a base material subjected to the above-mentioned anchoring property improving treatment can be preferably used. The above surface treatments may be used alone or in combination. The composition of the primer used for forming the undercoat layer is not particularly limited, and may be appropriately selected from known primers. The thickness of the undercoat layer is not particularly limited, and is usually about 0.01 μm to 1. Mu.m, preferably about 0.1 μm to 1. Mu.m. Examples of other treatments that may be applied to the first surface of the substrate as needed include antistatic layer formation treatment, coloring layer formation treatment, printing treatment, and the like.
In the case where the reinforcing film disclosed herein is in the form of a single-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on only the first side of the substrate, the second side of the substrate may be subjected to conventionally known surface treatments such as a peeling treatment and an antistatic treatment, if necessary. For example, by surface-treating the back surface of the substrate with a release agent (typically, by providing a release layer with a release agent), the unwinding force of the reinforcing film wound in a roll form can be reduced. As the release treatment agent, silicone release treatment agents, long-chain alkyl release treatment agents, olefin release treatment agents, fluorine release treatment agents, fatty acid amide release treatment agents, molybdenum sulfide, silica powder, and the like can be used. In addition, for the purpose of improving printability, reducing light reflectivity, improving re-adhesion, etc., the second surface of the substrate may be subjected to a treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, etc. In the case of the double-sided pressure-sensitive adhesive sheet, the second surface of the base material may be subjected to the same surface treatment as that described above as the surface treatment that can be performed on the first surface of the base material, if necessary. The surface treatment applied to the first surface of the substrate may be the same as or different from the surface treatment applied to the second surface.
< Properties of film for reinforcement >
The reinforcing film disclosed herein preferably has an initial adhesion force N measured after bonding to a stainless steel plate and holding at 23℃for 30 minutes 23 The limitation is below a predetermined value. In some embodiments, adhesion N 23 For example, it is preferably less than 500gf/25mm, more preferably less than 400gf/25mm, still more preferably less than 300gf/25mm, particularly preferably 250gf/25mm or less (for example, 200gf/25mm or less), and may be 150gf/25mm or less. Adhesive force N 23 Low is preferable from the viewpoint of reworkability. Adhesive force N 23 The lower limit of (2) is not particularly limited, and may be, for example, 1gf/25mm or more. From the viewpoint of workability of adhesion to an adherend, prevention of positional deviation before the adhesive force rises, and the like, the adhesive force N 23 It is usually preferably 10gf/25mm or more. From the viewpoint of improvement of adhesion after heating, etc., in some embodiments, the adhesion N 23 For example, the ratio may be 20gf/25mm or more, 50gf/25mm or more, 80gf/25mm or more, or 100gf/25mm or more (for example, 150gf/25mm or more).
Adhesive force N 23 [gf/25mm]The following holds: after being pressed against a stainless steel (SUS) plate as an adherend and left to stand in an atmosphere of 23℃and 50% RH for 30 minutes, 180℃peel adhesion was measured under the same atmosphere (i.e., at 23 ℃) under conditions of 180℃peel angle and 300mm/min tensile speed. As the adherend, SUS304BA plate was used. In the measurement, a suitable backing material (for example, a PET film having a thickness of about 25 μm) may be attached to the reinforcing film to be measured as needed for reinforcement. Adhesive force N 23 More specifically, the initial adhesion can be measured by the method for measuring initial adhesion described in the following examples.
The reinforcing film disclosed herein is a film obtained by heatingThe film having an increased adhesive strength may be, for example, an adhesive strength N of 300gf/25mm or more 60 I.e., adhesion measured at 23 c after adhering to a stainless steel plate and holding at 60 c for 60 minutes. In some embodiments, adhesion N 60 It is 400gf/25mm or more, preferably 500gf/25mm or more. After the reinforcing film satisfying the above characteristics is attached to an adherend, the adhesive force is increased to a predetermined value or more by heating. According to the techniques disclosed herein, strong adhesion can be obtained by heating. In some preferred embodiments, the adhesive force N 60 600gf/25mm or more, more preferably 700gf/25mm or more, 800gf/25mm or more, or 900gf/25mm or more. Adhesive force N 60 The upper limit of (2) is not particularly limited. From the viewpoint of ease of manufacturing and economy of the reinforcing film, in some embodiments, the adhesive force N 60 For example, 3000gf/25mm or less, 1500gf/25mm or less, or 1000gf/25mm or less.
Adhesive force N 60 [gf/25mm]The following holds: after being pressed against an SUS plate as an adherend and held at 60℃for 60 minutes, and then left at 23℃for 30 minutes in 50% RH, 180℃peel adhesion was measured at a peel angle of 180℃and a tensile speed of 300mm/min in the same environment. Adhesive force N as adherend 23 Also, SUS304BA plate was used. In the measurement, a suitable backing material (for example, a PET film having a thickness of about 25 μm) may be attached to the reinforcing film to be measured as needed for reinforcement. Adhesive force N 60 More specifically, the measurement can be performed based on the method for measuring the adhesive force after heating described in the following examples.
Adhesive force N 60 [gf/25mm]Relative to the adhesive force N 23 [gf/25mm]The ratio of (2), i.e. the adhesive force rising ratio N 60 /N 23 Without particular limitation, in some embodiments, N 60 /N 23 Preferably 1.5 or more, more preferably 2.0 or more, still more preferably 2.5 or more, still more preferably 3.0 or more (e.g., 3.5 or more), and may exceed 5.0 (e.g., exceed 7.0). By N 60 /N 23 The large reinforcing film can exhibit good reworkability at the initial stage of attachment and can be bonded by subsequent heating or the likeThe force rises greatly. N (N) 60 /N 23 The upper limit of (2) is not particularly limited, but is usually 100 or less, and may be 30 or less, 15 or less, or 10 or less from the viewpoint of ease of production and economy of the reinforcing film. In some ways, N 60 /N 23 For example, the content may be 5 or less, 3 or less, or 2 or less.
The adhesive force after heating of the reinforcing film disclosed herein indicates one characteristic of the reinforcing film, and is not limited to the manner of use of the reinforcing film. In other words, the mode of use of the reinforcing film disclosed herein is not limited to the mode of heating at 60℃for 60 minutes, and may be used, for example, in a mode of not particularly heating to a room temperature region (usually 20℃to 30℃and typically 23℃to 25 ℃) or more. In this manner of use, the adhesive force also increases over a long period of time, and firm bonding can be achieved. The reinforcing film disclosed herein can promote the increase of the adhesive force by heat treatment at a temperature exceeding 30 ℃ (for example, about 50 to 70 ℃) or higher than 60 ℃ at any time after the attachment. The heating temperature in the heating treatment is not particularly limited, and may be set in consideration of workability, economy, heat resistance of the base material of the reinforcing film, the adherend, and the like. The heating temperature may be, for example, less than 150 ℃, 120 ℃ or less, 100 ℃ or less, 80 ℃ or less, or 70 ℃ or less. The heating temperature may be, for example, 40℃or higher, 45℃or higher, 50℃or higher, 55℃or higher, 60℃or higher, or 70℃or higher, and may be 80℃or higher, or 100℃or higher. The heating time is not particularly limited, and may be, for example, 3 hours or less, 1 hour or less, 30 minutes or less, or 10 minutes or less. The heating time may be, for example, 1 minute or more, 15 minutes or more, 30 minutes or more, or 1 hour or more. Alternatively, the heat treatment may be performed for a longer period of time within the limits that the reinforcing film and the adherend do not undergo significant thermal degradation. The heat treatment may be performed at one time or may be performed in a plurality of times.
< reinforcing film with substrate >)
In the case where the reinforcing film disclosed herein is in the form of an adhesive sheet with a base material, the thickness of the reinforcing film may be 1000 μm or less, 600 μm or less, 350 μm or less, or 250 μm or less, for example. In some embodiments, the thickness of the reinforcing film may be, for example, 200 μm or less, 175 μm or less, 140 μm or less, 120 μm or less, or 100 μm or less (for example, less than 100 μm) from the viewpoints of downsizing, weight saving, thinning, etc. of a product to which the reinforcing film is applied. From the viewpoint of handleability, the thickness of the reinforcing film may be, for example, 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, or 30 μm or more. In some embodiments, the thickness of the reinforcing film may be, for example, 50 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, or 120 μm or more. The upper limit of the thickness of the reinforcing film is not particularly limited.
The thickness of the reinforcing film is the thickness of the portion to be attached to the adherend. For example, in the reinforcing film 1 having the structure shown in fig. 1, the thickness from the adhesive surface 21A of the reinforcing film 1 to the second surface 10B of the base material 10 is not limited to the thickness of the release liner 31.
The reinforcing film disclosed herein is preferably applied, for example, such that the thickness Ts of the support substrate is greater than the thickness Ta of the adhesive layer, that is, such that Ts/Ta is greater than 1. The ratio of Ts/Ta may be, for example, 1.1 or more, 1.2 or more, 1.5 or more, or 1.7 or more, and is not particularly limited. For example, increasing Ts/Ta tends to give good effects even when the reinforcing film is thinned. In some embodiments, ts/Ta may be 2 or more (e.g., greater than 2), may be 2.5 or more, or may be 2.8 or more. Further, the ratio of Ts/Ta may be 50 or less, or 20 or less, for example. From the viewpoint of easily exhibiting high adhesion after heating even when the reinforcing film is thinned, ts/Ta may be, for example, 10 or less, 8 or less, or 5 or less.
The adhesive layer is preferably fixedly connected to the support substrate. The term "fixed" as used herein means that, in the reinforcing film having an increased adhesive force after being attached to the adherend, the adhesive layer exhibits sufficient anchoring properties to the support substrate to such an extent that the adhesive layer does not peel off from the interface between the adhesive layer and the support substrate when the reinforcing film is peeled off from the adherend. The reinforcing film with the base material, which is fixed to the supporting base material by the adhesive layer, can firmly integrate the adherend with the supporting base material. As a preferable example of the reinforcing film in which the adhesive layer is fixed to the base material, there is given: the reinforcing film is free from peeling (anchor failure) between the adhesive layer and the support substrate when the adhesive force after heating is measured. The reinforcing film which does not cause anchor failure when the adhesive force after heating is measured is a preferable example of the reinforcing film in which the adhesive layer is fixed to the substrate.
The reinforcing film disclosed herein can be preferably produced, for example, by a method comprising the steps of: contacting the liquid adhesive composition with the first side of the 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 drying, crosslinking, polymerization, cooling, and the like of the adhesive composition. By the method of forming the adhesive layer by curing the liquid adhesive composition on the first surface of the substrate in this way, the anchoring property of the adhesive layer to the substrate can be improved as compared with a method of disposing the adhesive layer on the first surface of the substrate by bonding the cured adhesive layer to the first surface. In this case, the reinforcing film in which the adhesive layer is fixed to the base material can be suitably produced.
In some embodiments, as a method of bringing the liquid adhesive composition into contact with the first surface of the substrate, a method of directly applying the adhesive composition to the first surface of the substrate may be employed. By bringing the first surface (adhesive surface) of the adhesive layer cured on the first surface of the base material into contact with the release surface, a reinforcing film having a structure in which the second surface of the adhesive layer is fixed to the first surface of the base material and the first surface of the adhesive layer is brought into contact with the release surface can be obtained. The release surface may be a surface of a release liner, a back surface of a substrate subjected to a release treatment, or the like.
In the case of a photocurable adhesive composition using a part of a polymer (polymer slurry) as a monomer raw material, for example, the adhesive composition may be applied to a release surface, and then the first surface of a substrate may be covered with the applied adhesive composition, whereby the uncured adhesive composition is brought into contact with the first surface of the substrate, and in this state, the adhesive composition sandwiched between the first surface of the substrate and the release surface may be irradiated with light to be cured, thereby forming an adhesive layer.
The method illustrated above is not limited to the method for producing the reinforcing film disclosed herein. In the production of the reinforcing film disclosed herein, two or more suitable methods for fixing the adhesive layer to the first surface of the substrate may be used singly or in combination. Examples of such methods include: as described above, the method of forming the adhesive layer by curing the liquid adhesive composition on the first surface of the substrate includes a method of performing a surface treatment for improving the anchoring property of the adhesive layer on the first surface of the substrate. For example, when the anchoring property of the adhesive layer to the substrate can be sufficiently improved by providing a primer layer or the like on the first surface of the substrate, the reinforcing film can be produced by a method of bonding the cured adhesive layer to the first surface of the substrate. In addition, the anchoring property of the adhesive layer to the substrate can be improved by selecting the material of the substrate and selecting the composition of the adhesive. In addition, by applying a temperature higher than room temperature to the reinforcing film having the adhesive layer on the first surface of the substrate, the anchoring property of the adhesive layer to the substrate can be improved. The temperature used for improving the anchoring property may be, for example, about 35 to 80 ℃, about 40 to 70 ℃, or about 45 to 60 ℃.
In the case where the reinforcing film disclosed herein is in the form of an adhesive sheet having a first adhesive layer provided on a first surface of a substrate and a second adhesive layer provided on a second surface of the substrate (i.e., a double-sided adhesive sheet with a substrate), the first adhesive layer and the second adhesive layer may have the same structure or may have different structures. When the first adhesive layer and the second adhesive layer have different structures, the differences may be, for example, differences in composition, differences in structure (thickness, surface roughness, formation range, formation pattern, etc.). For example, the second adhesive layer may be an adhesive layer that does not contain polymer B. The surface elastic modulus of the surface of the second adhesive layer (second adhesive surface) at 23℃may be outside the range of 1 to 20kPa (for example, more than 20 kPa), or may be 30kPa or more.
< film for reinforcing with Release liner >)
The reinforcing film disclosed herein may be in the form of an adhesive product in which the surface (adhesive surface) of the adhesive layer is brought into contact with the release surface of the release liner. Therefore, according to the present specification, a release liner-attached adhesive sheet including any of the reinforcing films disclosed herein and a release liner having a release surface in contact with the adhesive surface of the reinforcing film can be provided.
The thickness of the release liner is not particularly limited, but is usually about 5 μm to 200 μm. When the thickness of the release liner is within the above range, the adhesion to the adhesive layer and the release from the adhesive layer are excellent, and thus are preferable. In some embodiments, the release liner may have a thickness of, for example, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. In addition, 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. The release liner may be subjected to known antistatic treatments such as a coating type, a kneading type, and a vapor deposition type, as necessary.
The release liner is not particularly limited, and for example, a release liner having a release layer on the surface of a liner substrate such as a resin film or paper (paper laminated with a resin such as polyethylene), a release liner comprising a resin film made of a low-adhesion material such as a fluorine-based polymer (polytetrafluoroethylene or the like) or a polyolefin-based resin (polyethylene, polypropylene or the like), and the like can be used. From the viewpoint of excellent surface smoothness, a release liner having a release layer on the surface of a resin film as a liner base material, and a release liner comprising a resin film formed of a low-adhesion material can be preferably used. The resin film is not particularly limited as long as it is a film capable of protecting the pressure-sensitive adhesive layer, and examples thereof include polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyester film (PET film, PBT film, etc.), polyurethane film, ethylene-vinyl acetate copolymer film, etc. For forming the release layer, for example, a known release agent such as a silicone release agent, a long-chain alkyl release agent, an olefin release agent, a fluorine release agent, a fatty acid amide release agent, molybdenum sulfide, or silica powder can be used. The use of a silicone release treating agent is particularly preferred.
The thickness of the release layer is not particularly limited, and is usually about 0.01 μm to 1. Mu.m, preferably about 0.1 μm to 1. Mu.m. The method of forming the release layer is not particularly limited, and a known method can be suitably used depending on the kind of the release treatment agent used and the like.
< usage >
The reinforcing film provided in the present specification can exhibit good reworkability at the initial stage of bonding to an adherend, for example, and thus can contribute to suppression of reduction in yield and improvement in quality of a product including the reinforcing film. The reinforcing film can be cured and heated after being attached to an adherend, thereby greatly improving the adhesive force. For example, by heating at an appropriate timing after the film is attached to the adherend, the reinforcing film can be firmly adhered to the adherend. With such characteristics, the reinforcing film disclosed herein can be preferably used in various fields for reinforcing members contained in various products.
The reinforcing film disclosed herein may be used, for example, in the form of a pressure-sensitive adhesive sheet with a base material having a pressure-sensitive adhesive layer provided on at least a first surface of a film-like base material having a first surface and a second surface, or as a reinforcing film to be attached to an adherend to reinforce the adherend. In the reinforcing film, a film base material including a resin film as a base film is preferably used as the film base material. In addition, from the viewpoint of improving the reinforcing performance, the pressure-sensitive adhesive layer is preferably fixed to the first surface of the film-like base material.
For example, in an optical member used in an optical product and an electronic member used in an electronic product, there is a possibility that a plurality of thin optical members/electronic members having different linear expansion coefficients and thicknesses may be stacked in a highly integrated manner, a small size, a light weight, and a thin profile. By attaching the reinforcing film to such a member, appropriate rigidity can be imparted to the optical member and the electronic member. Thus, the curling and bending due to the stress that may occur between the plurality of members having different linear expansion coefficients and different thicknesses can be suppressed in the manufacturing process and/or the manufactured product.
In addition, in the manufacturing process of the optical product/electronic product, in terms of performing shape processing such as cutting processing on the thin optical member/electronic member, the strong film is attached to the member for processing, so that local stress concentration on the optical member/electronic member accompanying processing can be relaxed, and risks such as cracks, breakage, and peeling of the laminated member can be reduced. Attaching the reinforcing member to the optical member/electronic member for processing can also help to alleviate local stress concentration in transportation, lamination, rotation, and the like of the member, suppress bending, and the like caused by the self weight of the member.
In addition, even when an apparatus such as an optical product or an electronic product including the reinforcing film is used by a consumer in the market, the pressure applied to the apparatus can be relaxed by including the reinforcing film in the case where the apparatus is inadvertently applied with stress, such as when the apparatus is dropped, when the apparatus is placed under a heavy object, when a flying object collides with the apparatus. Thus, by incorporating the reinforcing film into the above-described apparatus, the durability of the apparatus can be improved.
The reinforcing film disclosed herein can be preferably used, for example, by being attached to a member constituting various portable devices (portable equipment). The term "portable" is merely to be construed as being insufficient to be portable, which means to have a level of portability that an individual (standard adult) can relatively easily carry. Examples of the portable device include mobile phones, smart phones, tablet personal computers, notebook personal computers, various wearable devices, digital cameras, digital video cameras, audio devices (portable music players, IC recorders, etc.), calculators (desktop calculators), portable game devices, electronic dictionaries, electronic notepads, electronic books, in-vehicle information devices, portable radios, portable televisions, portable printers, portable scanners, portable electronic devices such as modems, mechanical wristwatches, pocket watches, flashlights, and hand mirrors. Examples of the members constituting the portable electronic device include a thin-layer display such as a liquid crystal display, an optical film used in an image display device such as a film-type display, a display panel, and the like. The reinforcing film disclosed herein can be preferably used as being attached to various members in automobiles, home electric appliances, and the like.
Further, the reinforcing film disclosed herein has bending recovery property and bending holding force, and therefore, can be preferably used so as to be attached to a member constituting a device having a bendable element (for example, a flexible device such as a flexible display; also referred to as a crimpable device or a foldable device). Examples of such devices include the various portable devices (portable equipment). Examples of the members constituting the above portable electronic apparatus may include: optical films, display panels, and the like used in image display devices such as liquid crystal displays and organic EL (electroluminescence) displays. The reinforcing film disclosed herein is preferably used for reinforcing members (typically, an image display device or the like called a flexible device or a foldable device) constituting such a portable electronic device.
The reinforcing film disclosed herein is suitable for use in reinforcing an optical member used as a constituent element of a liquid crystal display panel, a Plasma Display Panel (PDP), an organic EL display, or the like, for example, in the production, transportation, or the like of the optical member. The film is useful as a reinforcing film for optical members such as a polarizing plate (polarizing film), a wavelength plate, a retardation plate, an optical compensation film, a brightness enhancement film, a light diffusion sheet, and a reflection sheet for a liquid crystal display panel.
The application of the reinforcing film disclosed herein is not particularly limited, and the film may be used for various applications for the purpose of imparting rigidity, impact resistance, and the like. The reinforcement films disclosed herein are preferably used not only for flexible device applications, as described above, but also for other applications not including flexible devices. The fact that the reinforcing film has bending recovery properties and bending retention force means that the reinforcing film has a small limitation in application range, which is a great advantage in practical applications.
Examples
The following describes several embodiments related to the present invention, but is not intended to limit the present invention to those shown in the specific examples. In the following description, "parts" and "%" refer to weight unless otherwise specified.
[ Synthesis of Polymer (A) ]
Synthesis example A1
To a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube and a condenser, 90.2 parts of 2-ethylhexyl acrylate (2 EHA), 8.6 parts of 4-hydroxybutyl acrylate (4 HBA), 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 introduced while stirring slowly, and the temperature of the liquid in the flask was kept at about 65 ℃ for polymerization for 6 hours to prepare an acrylic polymer A1 solution having a polymer concentration of 35%. The weight average molecular weight (Mw) of the acrylic polymer A1 was 54 ten thousand.
Synthesis example A2
Solution polymerization was performed in the same manner as in Synthesis example A1 except that the monomer composition was changed to 2EHA/4 HBA/ACMO/Butyl Acrylate (BA) =86.1 parts/9.7 parts/1.8 parts/2.4 parts, thereby obtaining a solution of an acrylic polymer A2.
Synthesis example A3
Solution polymerization was performed in the same manner as in synthesis example A1 except that the monomer composition was changed to BA/4 hba=96 parts/4 parts, thereby obtaining a solution of the acrylic polymer A3.
Synthesis example A4
Solution polymerization was performed in the same manner as in Synthesis example A1 except that the monomer composition was changed to 2 EHA/2-hydroxyethyl acrylate (HEA)/Methyl Methacrylate (MMA)/N-vinyl-2-pyrrolidone (NVP) =65 parts/15 parts/7 parts/13 parts, to thereby obtain a solution of acrylic polymer A4.
[ Synthesis of Polymer (B) ]
Synthesis example B1
101.15 parts of ethyl acetate, 40 parts of MMA, 20 parts of n-butyl methacrylate (nBMA), 20 parts of 2-ethylhexyl methacrylate (2 EHMA), 8.7 parts of a polyorganosiloxane-skeleton-containing methacrylate monomer (trade name: X-22-174ASX, manufactured by Xinyue chemical industry Co., ltd.) having a functional group equivalent of 900g/mol, 11.3 parts of a polyorganosiloxane-skeleton-containing methacrylate monomer (trade name: KF-2012, manufactured by Xinyue chemical industry Co., ltd.) having a functional group equivalent of 4600g/mol, and 0.8 part of thioglycerol as a chain transfer agent were charged into a four-necked flask equipped with a stirring blade, a thermometer, nitrogen, a condenser and a dropping funnel. Then, after stirring at 70℃for 30 minutes under a nitrogen atmosphere, 0.2 part of AIBN as a thermal polymerization initiator was charged and the reaction was carried out at 70℃for 3 hours. Next, after stirring at 80℃for 30 minutes, 0.1 part of AIBN was added thereto, and the reaction was carried out at 80℃for 2 hours. Thereafter, 0.05 part of AIBN was added thereto, and the reaction was carried out at 80℃for 2 hours to obtain a polymer B1. The Mw of the resulting polymer B1 was 20000, tg (T B ) Is-13.8 ℃.
Synthesis examples B2 to B6
Polymers B2 to B6 were produced in the same manner as in the production of polymer B1, except that the composition of the monomer components was changed as shown in table 1. Tg (T) of each Polymer B ) Polymer B2 was-8.4 ℃, polymer B3 was-7.2 ℃, polymer B4 was-0.6 ℃, polymer B5 was-25.1 ℃ and polymer B6 was 9.4 ℃. In Table 1, MMA represents methyl methacrylate (Tg 105 ℃ C.), nBMA represents n-butyl methacrylate (Tg 20 ℃ C.), 2EHMA represents 2-ethylhexyl methacrylate (Tg-10 ℃ C.), iBMA represents isobutyl methacrylate (Tg 48 ℃ C.), CHMA represents cyclohexyl methacrylate (Tg 66 ℃ C.), X-22-174ASX represents a polyorganosiloxane-skeleton-containing methacrylate monomer (trade name: X-22-174ASX, manufactured by Xin Yue chemical industry Co., ltd.) in terms of functional group equivalent900 g/mol), KF-2012 represents a polyorganosiloxane skeleton-containing methacrylate monomer (trade name: KF-2012, believed to be manufactured by chemical industry Co., ltd.) functional group equivalent 4600 g/mol.
The compositions of the monomer components used for preparing the polymers B1 to B6 and the Tg (T) of the polymers B1 to B6 B ) The results are summarized in Table 1.
TABLE 1
TABLE 1
Figure BDA0004113439390000521
Mw of each of the above polymers was measured under the following conditions using a GPC apparatus (HLC-8220 GPC manufactured by Tosoh Co., ltd.) and was calculated by conversion to polystyrene.
GPC conditions ]
Sample concentration: 0.2 wt% (tetrahydrofuran (THF) solution)
Sample injection amount: 10. mu.l
Eluent: THF, flow rate: 0.6 ml/min
Measurement temperature: 40 DEG C
Column:
sample column: TSKguardcolumn SuperHZ-H (1 root) +TSKgel SuperHZM-H (2 roots)
Reference column: TSKgel SuperH-RC (1 root)
Detector: differential Refractometer (RI)
[ production of reinforcing film ]
Example 1 >
100 parts of an acrylic polymer A1, 2.0 parts of a polymer B1, and 0.10 parts of an isocyanate compound C1 (trade name "Coronate HX", manufactured by Tosoh Co., ltd.) as a crosslinking agent in terms of solid content were added, and the mixture was diluted with ethyl acetate until the solid content of the whole became 30%, to obtain an acrylic pressure-sensitive adhesive solution of this example.
A release liner (trade name "diafil MRF75", manufactured by mitsubishi chemical company) formed of a polyester resin having a thickness of 75 μm and having been subjected to silicone treatment on one surface thereof was prepared, and the acrylic adhesive solution obtained as described above was applied to the silicone treated surface thereof, and dried at 130 ℃ for 1 minute, thereby forming an adhesive layer having a thickness of 25 μm.
Next, a polyimide substrate (trade name "Upilex 50S", manufactured by yu-gaku corporation) having a thickness of 50 μm was bonded to the surface of the obtained pressure-sensitive adhesive layer to obtain a reinforcing film of this example. The reinforcing film has a form of a release liner-attached adhesive sheet having an adhesive layer on one side of a base material and a release liner-attached release surface in contact with the adhesive surface.
In the reinforcing film of this example, the molar ratio ([ NCO ]/[ OH ]) was calculated from the OH amount (the number of moles of hydroxyl groups in the acrylic polymer A1) and the NCO amount (the number of moles of isocyanate groups in the isocyanate compound) in the adhesive layer, and was found to be 0.008.
Examples 2 to 3 >
Acrylic pressure-sensitive adhesive solutions of respective examples were obtained in the same manner as in example 1, except that the polymer B2 (example 2) and the polymer B3 (example 3) were used in place of the polymer B1. The reinforcing films of each example were produced in the same manner as in the production of the reinforcing film of example 1, except that the acrylic adhesive solutions were used.
Examples 4 to 7 >
An acrylic pressure-sensitive adhesive solution was obtained in the same manner as in example 1 except that the amount of the isocyanate compound C1 used was changed to 0.015 part (example 4), 0.05 part (example 5), 0.20 part (example 6) and 0.60 part (example 7) in terms of solid content relative to 100 parts of the acrylic polymer A1 as shown in table 2. The reinforcing films of each example were produced in the same manner as in the production of the reinforcing film of example 1, except that the acrylic adhesive solutions were used.
Examples 8 to 10 >
Acrylic pressure-sensitive adhesive solutions of respective examples were obtained in the same manner as in example 1 except that the amount of the polymer B1 used was changed to 1.0 part (example 8), 3.0 parts (example 9) and 6.0 parts (example 10) based on 100 parts of the acrylic polymer A1 as shown in table 2. The reinforcing films of each example were produced in the same manner as in the production of the reinforcing film of example 1, except that the acrylic adhesive solutions were used.
Example 11 >
An acrylic pressure-sensitive adhesive solution of this example was obtained in the same manner as in example 1, except that the acrylic polymer A2 was used in place of the acrylic polymer A1. The reinforcing film of this example was produced in the same manner as in the production of the reinforcing film of example 1, except that the obtained acrylic pressure-sensitive adhesive solution was used.
Example 12 >
An acrylic pressure-sensitive adhesive solution of this example was obtained in the same manner as in example 1, except that the acrylic polymer A3 was used in place of the acrylic polymer A1, and an isocyanate compound C2 (trade name "Takenate D110N", manufactured by mitsubishi chemical company) was used as a crosslinking agent, wherein the isocyanate compound C2 was 0.07 part in terms of solid content relative to 100 parts of the acrylic polymer A3. The reinforcing film of this example was produced in the same manner as in the production of the reinforcing film of example 1, except that the obtained acrylic pressure-sensitive adhesive solution was used.
Example 13 >
An acrylic pressure-sensitive adhesive solution of this example was obtained in the same manner as in example 12 except that the amount of the isocyanate compound C2 used was changed to 0.09 part in terms of solid content based on 100 parts of the acrylic polymer A3 as shown in table 2. The reinforcing film of this example was produced in the same manner as in the production of the reinforcing film of example 1, except that the obtained acrylic pressure-sensitive adhesive solution was used.
Comparative examples 1 and 2
Acrylic pressure-sensitive adhesive solutions of respective examples were obtained in the same manner as in example 1, except that the polymer B5 (comparative example 1) and the polymer B6 (comparative example 2) were used in place of the polymer B1. The reinforcing films of each example were produced in the same manner as in the production of the reinforcing film of example 1, except that the acrylic adhesive solutions were used.
Comparative example 3 >
An acrylic pressure-sensitive adhesive solution of this example was obtained in the same manner as in example 1, except that the acrylic polymer A4 was used in place of the acrylic polymer A1, and an isocyanate compound C2 (trade name "Takenate D110N", manufactured by mitsubishi chemical company) was used as a crosslinking agent, wherein the isocyanate compound C2 was 0.50 part in terms of solid content relative to 100 parts of the acrylic polymer A4. The reinforcing film of this example was produced in the same manner as in the production of the reinforcing film of example 1, except that the obtained acrylic pressure-sensitive adhesive solution was used.
Comparative examples 4 to 5
An acrylic pressure-sensitive adhesive solution was obtained in the same manner as in comparative example 3 except that the amount of the isocyanate compound C2 used was changed to 1.10 parts (comparative example 4) and 2.50 parts (comparative example 5) in terms of solid content per 100 parts of the acrylic polymer A4 as shown in table 2. The reinforcing films of each example were produced in the same manner as in the production of the reinforcing film of example 1, except that the acrylic adhesive solutions were used.
Example 14 >
An acrylic pressure-sensitive adhesive solution of this example was obtained in the same manner as in example 1, except that the polymer B4 was used in place of the polymer B1. The reinforcing film of this example was produced in the same manner as in the production of the reinforcing film of example 1, except that the obtained acrylic pressure-sensitive adhesive solution was used.
< evaluation >
[ surface elastic modulus ]
For each reinforcing film, the film was cured at 50℃for 1 day, and the surface elastic modulus was measured. The release liner protecting the adhesive surface was peeled off, and the surface of the adhesive layer was pressed into a press head to a press depth of 6 μm by using a nanoindenter device (Triboindeter manufactured by Hysicron Inc.), and the maximum load (Pmax) [ GPa/mm) was obtained by measurement using the nanoindenter 2 ]. Substituting the obtained product into the following formula, and calculating the surface hardness, and converting the calculated product into [ kPa ]]Units are reported as the surface elastic modulus at 23 ℃ (23 ℃ surface elastic modulus). The measurement conditions are as follows. In the above description, A is the contact projection area [ mm ] of the indenter 2 ]。
Surface hardness [ GPa ] =pmax/a
(measurement conditions)
Pressure head approach speed: 5 μm/s
Maximum displacement: 6 μm
Press-in speed: 5 μm/s
Extraction rate: 5 μm/s
Using a pressure head: cone (spherical pressure head: radius of curvature 10 μm)
The measuring method comprises the following steps: single press-in assay
Measuring temperature: room temperature (23 ℃ C.)
[ bulk modulus G' and tan delta ]
A release liner R1 (trade name "diafil MRF75", manufactured by mitsubishi chemical company) made of a polyester resin, each of which had been subjected to silicone treatment on one surface thereof, was prepared, and an acrylic adhesive solution of each example was applied to the silicone treated surface thereof, and dried at 130 ℃ for 1 minute, thereby forming an adhesive layer having a thickness of 25 μm. Then, a release liner R2 (trade name "DIAFOIL MRE75", manufactured by Mitsubishi chemical corporation) made of a polyester resin, which had been subjected to silicone treatment on one side thereof and had a thickness of 75 μm, was coated on the surface of the obtained pressure-sensitive adhesive layer so that the silicone-treated surface was on the pressure-sensitive adhesive layer side, and curing was performed at 50℃for 1 day.
Only the obtained adhesive layer was taken out, laminated to a thickness of about 1mm, die-cut to a diameter of 8mm, and a columnar pellet was produced as a sample for measurement.
The above measurement sample was fixed to a jig having a parallel plate of phi 8mm, and the storage modulus G ', loss modulus G "and loss tangent tan delta were measured by a dynamic viscoelasticity measuring apparatus (ARES manufactured by TA Instruments Co.) under the following conditions to obtain the storage modulus G ' at 23℃ ' 23 [kPa]Storage modulus G 'at 80℃' 80 [kPa]And tan delta at 80 ℃ (loss modulus G' at 80℃ " 80 Storage modulus G 'at 80 ℃' 80 )。
Measurement mode: shear mode
Temperature range: -70-200 DEG C
Temperature increase rate: 5 ℃/min
Frequency: 1Hz
The storage modulus G' corresponds to a portion that is stored as elastic energy when the material is deformed, and is an index indicating the degree of hardness. The loss modulus g″ corresponds to a loss energy portion dissipated by internal friction or the like when the material is deformed, and indicates the degree of tackiness.
[ initial adhesion ]
For each reinforcing film, curing was performed at 50℃for 1 day, and the film was cut into a width of 25 mm. Times.140 mm in length together with a release liner, to obtain a measurement sample. The release liner was peeled off from the above measurement sample, the adhesive surface was exposed, and a 2kg hand press roller was reciprocated 1 time to press-bond the release liner to a stainless steel plate (SUS 304BA plate) as an adherend. After the measurement sample thus pressure-bonded to the adherend was left at an ambient temperature of 23℃for 30 minutes, the load at the time of peeling the reinforcing film from the adherend was measured under conditions of a peeling angle of 180 degrees and a peeling speed (stretching speed) of 300mm/min using a tensile tester (trade name "Autograph AG-Xplus HS 6000mm/min high speed mode (AG-50 NX plus)") manufactured by Shimadzu corporation), and the average load at the time of measurement was recorded as initial adhesive force [ gf/25mm ].
[ adhesion after heating ]
For the reinforcing films of each example, a measurement sample was prepared in the same manner as the initial adhesion measurement described above, and was pressure-bonded to an adherend. Then, the measurement sample crimped to the adherend was heated at 60℃for 60 minutes. Thereafter, the film was left to stand at an ambient temperature of 23℃for 30 minutes, and the load when peeling the reinforcing film from the adherend was measured under conditions of a peeling angle of 180℃and a peeling speed (stretching speed) of 300mm/min using a tensile tester (trade name "Autograph AG-Xplus HS 6000mm/min high speed mode (AG-50 NX plus)") manufactured by Shimadzu corporation, and the average load at the time of measurement was recorded as the adhesive force after heating [ gf/25mm ].
[ bending holding test ]
For each reinforcing film, after curing at 50℃for 1 day, the release liner was peeled off, and a polyimide substrate having a thickness of 25 μm (trade name "Upsilex 25S", manufactured by Yu Xingxi Co., ltd.) was bonded to the exposed adhesive surface, and heated at 60℃for 60 minutes to bond the films. Next, the obtained measurement sample (laminate) was bent to have a diameter of 6mm with the 25 μm substrate side as the inner side, and was fixed in this state, and heated at 80℃for 15 hours. Then, the sample was left at room temperature (23 ℃) and after confirming sufficient cooling, the fixation of the bent state of the measurement sample was released, and the bending angle [ ° ] of the bent measurement sample was measured using an indexer within 10 minutes from the release of the fixation, and the bending recovery was evaluated. The bending angle is the opening angle of the measurement sample (the angle of the side of the measurement sample that is opened from the bent state), and the bending recovery is excellent as the bending angle approaches 180 °, and the bending recovery is inferior as the bending angle approaches 0 °.
Next, as an evaluation of the bending holding force, whether the bending portion of the measurement sample was "peeled off" was visually confirmed, and the case where "peeled off" was not confirmed was evaluated as "o", and the case where "peeled off" was confirmed was evaluated as "x".
The evaluation results of the reinforcing films of examples 1 to 13 and comparative examples 1 to 5 are shown in table 2. Table 2 also shows the outline of the composition of the adhesive layer of each example.
TABLE 2
Figure BDA0004113439390000591
Table 3 shows the evaluation results of the bending recovery and the recovery retention of the reinforcing film of example 14 together with the outline (composition and characteristics of the adhesive layer) of example 14.
TABLE 3
TABLE 3 Table 3
Figure BDA0004113439390000601
As shown in Table 2, the adhesives of examples 1 to 13 contain a polymer (A) and a polymer (B), and the Tg of the polymer (B) is in the range of-20℃to 5 ℃. The reinforcing films of these examples are better in terms of both low initial adhesion and increase in adhesion after heating than those of comparative examples 1 to 2 in which the Tg of the polymer (B) is outside the range of-20℃to 5 ℃. In addition, the reinforcing films of examples 1 to 13 were excellent in bending recovery and bending retention in the range of 1 to 20kPa in terms of the surface elastic modulus at 23 ℃. On the other hand, in comparative examples 3 to 5 in which the surface elastic modulus at 23℃was out of the range of 1 to 20kPa, peeling was confirmed in the bending retention test.
More specifically, as is clear from the comparison of examples 1 to 3, the higher the Tg of the polymer (B) is in the range of-20℃to 5℃is, the higher the adhesive strength after heating is achieved, and the lower the initial adhesive strength is, the more the initial light peelability is liable to be improved. On the other hand, in comparative example 1 in which the Tg of the polymer (B) was less than-20 ℃, the initial adhesion was high and the light peelability was poor. In comparative example 2 in which the Tg of the polymer (B) exceeded 5 ℃, the increase in adhesive force after heating was small. Further, as is clear from the comparison of examples 4 to 7, it was confirmed that the higher the surface elastic modulus at 23℃of the adhesive layer was in the range of 1 to 20kPa, the more improved the bending recovery was tended to be, and the initial adhesion and the adhesion after heating tended to be low. The bending recovery properties of examples 5 to 7 are superior to those of example 4, the surface elastic modulus at 23℃is 2kPa or more, and the tan delta at 80 DEG C 80 In the range of 0.10 to 0.60. In example 7, the surface elastic modulus and the bulk elastic modulus were both high, and the adhesive force after heating was increased relatively lower than in examples 4 to 6. In examples 4 to 6, the bulk modulus G 'at 23℃of the adhesive layer was not confirmed' 23 Is a difference in (a) between the two. In addition, the 80℃bulk modulus G 'in examples 1 to 3 and 5' 80 To the same extent. Examples 1 to 7 were said to have a higher correlation between the surface elastic modulus at 23℃and the bending recovery property than the bulk elastic modulus. In examples 1 to 7, the initial adhesion, the adhesion after heating, the bending recovery property, and the bending holding power were improved more uniformly, and the molar ratio of isocyanate groups to hydroxyl groups ([ NCO]/[OH]) In the range of 0.002 to 0.03.
Further, it was confirmed from the comparison of examples 8 to 10 that the adhesive force tends to decrease as the amount of the polymer (B) used increases. In examples 8 to 9, in which the amount of the polymer (B) used was in the range of 0.5 to 5 parts per 100 parts of the polymer (A), the initial adhesion was less than 400gf/25mm, and the adhesion after heating was 500gf/25mm or more, and the light peelability at the initial stage of the application and the increase in the adhesion after heating were both better. Further, when the amount of the polymer (B) used is increased, the surface elastic modulus at 23℃tends to be high, and the bending recovery tends to be low. Further, it was confirmed from the results of examples 11 to 13 that: even if the kind of the polymer (a) and the kind of the crosslinking agent of the binder are changed, the desired effect can be achieved.
Further, as shown in table 3, it can be confirmed that: in example 14 in which the adhesive layer has a surface elastic modulus at 23℃in the range of 1 to 20kPa and the polymer (B) having a Tg of-1.6℃is used, both the bending recovery property and the bending retention force can be achieved. Although not particularly shown in the table, the initial adhesive force of the reinforcing film of example 14 was less than 400gf/25mm (specifically, less than 200gf/25 mm), and the adhesive force was increased after heating (adhesive force increase ratio N) 60 /N 23 ) The effect of the techniques disclosed herein is achieved at 7 (times).
Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of protection of the claims. The claims include modifications and variations of the specific examples described above.
Description of the reference numerals
1,2, 3-reinforcing film
10 support substrate
10A first side
10B second side
21 adhesive layer (first adhesive layer)
21A adhesive surface (first adhesive surface)
21B adhesive surface (second adhesive surface)
22 adhesive layer (second adhesive layer)
22A adhesive side (second adhesive side)
31,32 release liner
100,200,300 film with release liner for reinforcement

Claims (7)

1. A reinforcing film comprising an adhesive layer,
The adhesive layer comprises a polymer (A) and a polymer (B),
the polymer (B) comprises a monomer unit having a polyorganosiloxane skeleton and a (meth) acrylic monomer unit,
the adhesive layer has a surface elastic modulus at 23 ℃ of 1 to 20kPa,
glass transition temperature T of the polymer (B) B Is at a temperature of between-20 ℃ and 5 ℃.
2. The reinforcing film according to claim 1, wherein the adhesive layer has a bulk modulus G 'at 23 °c' 23 A bulk modulus G 'at 80℃of 10 to 200 kPa' 80 5 to 100kPa, and tan delta at 80 DEG C 80 0.10 to 0.60.
3. The reinforcing film according to claim 1 or 2, wherein the polymer (a) is an acrylic polymer.
4. The reinforcing film according to any one of claims 1 to 3, wherein the content of the polymer (B) in the adhesive layer is 0.5 to 5 parts by weight relative to 100 parts by weight of the polymer (a).
5. The reinforcing film according to any one of claims 1 to 4, wherein a molar ratio of isocyanate groups to hydroxyl groups, i.e., [ NCO ]/[ OH ], contained in the adhesive layer is 0.002 to 0.03.
6. An optical member to which the reinforcing film according to any one of claims 1 to 5 is attached.
7. An electronic component to which the reinforcing film according to any one of claims 1 to 5 is attached.
CN202180057328.5A 2020-08-06 2021-07-27 Reinforcing film, optical member, and electronic member Pending CN116034027A (en)

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