阅读说明：本技术 粘合片、光学构件、及显示装置 (Adhesive sheet, optical member, and display device ) 是由 冲田奈津子 三井数马 林圭治 于 2019-01-29 设计创作，主要内容包括：本发明的目的在于,提供通过将刚性弱的基材和容易追随弯曲部、凹凸部的粘合剂层组合,从而在作为被粘物的具有弯曲部、凹凸部这样的光学构件、显示装置、构成显示装置的显示器等制造·加工时、搬运时、出货检查时、输送时等能够追随被粘物、能够充分保护被粘物的粘合片(表面保护薄膜)。本发明的粘合片的特征在于,在基材薄膜的单面或双面具有由粘合剂组合物形成的粘合剂层,前述基材薄膜为非聚烯烃系薄膜,将前述粘合片切断为宽度50mm、长度100mm并以在长度方向超出50mm的方式固定于水平的台子时的垂直下垂距离L为30mm以上,将前述粘合剂层表面贴合于玻璃、并在90度方向以1mm/分钟的剥离速度进行拉伸时的剥离力为3.0gf/50mm以上。(An object of the present invention is to provide a pressure-sensitive adhesive sheet (surface protecting film) which can follow an adherend and sufficiently protect the adherend during manufacturing/processing, transportation, shipment inspection, transportation, and the like of an optical member having a curved portion and an uneven portion as an adherend, a display device, and a display constituting the display device, by combining a base material having low rigidity and a pressure-sensitive adhesive layer which can easily follow the curved portion and the uneven portion. The pressure-sensitive adhesive sheet of the present invention is characterized in that the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition on one or both surfaces of a substrate film, the substrate film is a non-polyolefin film, the vertical sagging distance L when the pressure-sensitive adhesive sheet is cut to a width of 50mm and a length of 100mm and fixed on a horizontal table so as to exceed 50mm in the longitudinal direction is 30mm or more, and the peel force when the pressure-sensitive adhesive layer is surface-bonded to glass and stretched at a peel speed of1 mm/min in a 90-degree direction is 3.0gf/50mm or more.)

1. A pressure-sensitive adhesive sheet characterized by having a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive composition on one or both sides of a base film,

the base film is a non-polyolefin film,

the vertical sagging distance L when the adhesive sheet is cut to a width of 50mm and a length of 100mm and fixed to a horizontal table so as to exceed 50mm in the longitudinal direction is 30mm or more,

the adhesive layer has a peel force of 3.0gf/50mm or more when the adhesive layer is surface-bonded to glass and stretched at a peel speed of1 mm/min in a 90-degree direction.

2. The adhesive sheet according to claim 1, wherein the adhesive layer is formed from an adhesive composition containing at least 1 selected from the group consisting of an acrylic adhesive, a urethane adhesive, and a silicone adhesive.

3. The adhesive sheet according to claim 1 or 2, wherein the non-polyolefin film has a tensile modulus of elasticity of less than 1.5 × 10⁹Pa。

4. The adhesive sheet according to any one of claims 1 to 3, wherein the non-polyolefin film is a polyester film.

5. An optical member protected by the adhesive sheet according to any one of claims 1 to 4.

6. A display device protected by the adhesive sheet according to any one of claims 1 to 4.

Technical Field

The present invention relates to an adhesive sheet, particularly a surface protective film. The surface protective film is preferably used for the purpose of protecting the surface of an optical member or a display device by being attached to the surface. Examples of the optical member include an ITO film, a polarizing plate, a diffusion plate, a brightness enhancement film, a glass cover sheet, an organic EL panel in which these are laminated, a liquid crystal panel, and the like. Examples of the display device include a monitor, a television, and a smartphone.

Background

In general, a surface protective film has a structure in which an adhesive layer is provided on a film-like base film (support). The surface protective film is bonded to an optical member as an adherend, a display device including the optical member, or the like via the pressure-sensitive adhesive layer, and is used for the purpose of protecting the surface of the optical member or the like from damage or contamination during manufacturing or processing, transportation, shipment inspection, transportation, or the like of the optical member, the electronic member constituting the display device, or the like. Then, after the pressure-sensitive adhesive layer surface of the surface protecting film is actually used by being attached to an optical member, a display device, or the like, the surface protecting film is peeled and removed at a stage where it is unnecessary.

In addition, when the surface protective film is attached to an optical member, a display device including an optical member, or a display (screen) constituting a display device, a substrate having a thickness (for example, polyethylene terephthalate or the like) may be used from the viewpoint of handleability in manufacturing and processing, or from the viewpoint of bonding the surface protective film to the display or the like.

However, when a surface protection film using a substrate having a thickness is bonded to a display or the like constituting a display device having a curved portion and an uneven portion, the surface protection film cannot follow the curved portion and the uneven portion due to the high rigidity of the substrate.

On the other hand, as in patent documents 1 and 2, when a non-oriented polypropylene (CPP) having low rigidity, Polyethylene (PE), or the like is used as a base material of a surface protective film, there are cases where defects such as appearance characteristics called fish eyes occur, and defects cannot be recognized at the time of shipment inspection.

Further, in recent years, there have been increasing numbers of optical members, display devices, and displays constituting display devices each having a curved portion and a concave-convex portion, and there has been a demand for a surface protective film capable of protecting the optical members, the display devices, and the displays constituting the display devices in accordance with the curved portions and the concave-convex portions in the manufacturing process and the shipment process of the displays.

Disclosure of Invention

Problems to be solved by the invention

The present inventors have therefore conducted intensive studies in view of the above circumstances, and as a result, have found a pressure-sensitive adhesive sheet (surface-protecting film) which can follow an adherend and sufficiently protect the surface thereof when manufacturing and processing an optical member having a curved portion and a concave-convex portion as the adherend, a display device constituting the display device, and the like, or when carrying, shipping inspection, transportation, and the like, the optical member having a curved portion and a concave-convex portion, and the pressure-sensitive adhesive layer which easily follows a curved surface such as a curved portion and a concave-convex portion are combined, and have completed the present invention.

Means for solving the problems

That is, the pressure-sensitive adhesive sheet of the present invention is characterized in that the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition on one side or both sides of a substrate film, the substrate film is a non-polyolefin film, the vertical sagging distance L when the pressure-sensitive adhesive sheet is cut into a width of 50mm and a length of 100mm and fixed to a horizontal table so as to exceed 50mm in the longitudinal direction is 30mm or more, and the peel force when the pressure-sensitive adhesive layer is surface-bonded to glass and stretched at a peel speed of1 mm/min in a 90-degree direction is 3.0gf/50mm or more.

In the adhesive sheet of the present invention, the adhesive layer is preferably formed from an adhesive composition containing at least 1 selected from the group consisting of an acrylic adhesive, a urethane adhesive, and a silicone adhesive.

The pressure-sensitive adhesive sheet of the invention is preferably such that the non-polyolefin film has a tensile elastic modulus of less than 1.5 × 10⁹Pa。

In the adhesive sheet of the invention, the non-polyolefin film is preferably a polyester film.

The optical member of the present invention is preferably protected by the adhesive sheet.

The display device of the present invention is preferably protected by the adhesive sheet.

ADVANTAGEOUS EFFECTS OF INVENTION

The pressure-sensitive adhesive sheet of the present invention is useful in that it can follow a substrate film having low rigidity and capable of following a curved surface such as a curved portion or an uneven portion, and a pressure-sensitive adhesive layer having good adhesive properties to the curved surface such as a curved portion or an uneven portion, and thus can obtain a pressure-sensitive adhesive sheet (surface protecting film) having excellent protective properties, which can be followed by the pressure-sensitive adhesive sheet during manufacturing and processing, transportation, shipment inspection, transportation, and the like of an optical member such as a curved portion or an uneven portion, a display device, and a display constituting the display device.

Drawings

Fig. 1 is a schematic view of the adhesive sheet when the vertical sagging distance L is measured.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail.

< integral Structure of adhesive sheet (surface protective film) >

The pressure-sensitive adhesive sheet (surface protecting film) disclosed herein is suitable as a surface protecting film for protecting the surface of an optical member, a display device (a display constituting a display device), and the like, particularly, a display having a curved portion and a concave-convex portion, when manufacturing and processing, carrying, shipping inspection, transportation, and the like, in the form of a pressure-sensitive adhesive layer surface generally called a pressure-sensitive adhesive tape, a pressure-sensitive adhesive label, a pressure-sensitive adhesive film, and the like. The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet is typically formed continuously, but is not limited to the above-described embodiment, and may be formed in a regular or irregular pattern such as dots or stripes, for example. The pressure-sensitive adhesive sheet disclosed herein may be in the form of a roll or a sheet.

< substrate film >

The pressure-sensitive adhesive sheet of the present invention is characterized by comprising a substrate film, wherein the substrate film is a non-polyolefin film. The reason why the polyolefin-based film is weaker in rigidity than the non-polyolefin-based film is presumed that the unsaturated bond is small and the rotation of the carbon chain is not restricted. However, when a polyolefin-based film is used as a base film constituting a surface protective film, a defect called fisheye in appearance characteristics, a defect that cannot be confirmed at the time of shipment inspection, and the like may occur, which is not preferable. The fish eyes mean that transparent or translucent particles such as fish eyes remain in the base film in the film forming step of the base film, and the gel or unmelted resin is a cause of the generation of fish eyes. When a polyolefin-based film is used as the base film, the melt viscosity of the resin is high, and the resin cannot pass through a high-precision filter in the film forming step, so that unmelted material cannot be removed, and the film tends to contain a large amount of fish eyes, which is not preferable. In particular, in the case of polyethylene, when radicals are generated in the molecules during melting of the resin, the polyethylene molecules react with each other and easily gel, and therefore, in particular, many fish eyes are generated, which makes it difficult to use the polyethylene for optical use, and is not preferable. On the other hand, since the non-polyolefin-based film has a low melt viscosity, it is possible to remove unmelted matter that causes fish eyes by a high-precision filter during film formation, and thus it is possible to obtain a film having excellent appearance characteristics, and it is applicable to optical applications.

The base film (base material, support) is a non-polyolefin film, and for example, a plastic film made of a resin material selected from polyester polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate; cellulose polymers such as cellulose diacetate and cellulose triacetate; a polycarbonate-series polymer; an acrylic polymer such as polymethyl methacrylate or the like as a main resin component (a component which occupies 50% by weight or more of the main component in the resin component). Among these, the non-polyolefin-based film is preferably a polyester film using a polyester polymer, and among these, a non-polyolefin-based film excellent in optical properties (such as transparency), mechanical strength, thermal stability, moisture-shielding properties, isotropy, flexibility, dimensional stability, and the like is preferably used. In particular, a polyester film having insufficient rigidity as a base film is useful because it has flexibility, and thus the adhesive composition can be applied by a roll coater or the like and can be wound up in a roll form. Further, as the polyester film, a film having 2 or more ester bonds may be used, and a combination of polyethylene terephthalate and polybutylene terephthalate may be preferably used.

Other examples of the resin material include styrene polymers such as polystyrene and acrylonitrile-styrene copolymer; a vinyl chloride polymer; amide polymers such as nylon 6,6 and aromatic polyamide; etc. as the resin material. Examples of the resin material include imide polymers, sulfone polymers, polyethersulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, and epoxy polymers. The base film may be a base film formed from a mixture of 2 or more of the above polymers.

In the adhesive sheet of the invention, the non-polyolefin film preferably has a tensile elastic modulus of less than 1.5 × 10⁹Pa, more preferably 1.3 × 10⁹Pa or less, more preferably 1.0 × 10⁷～1.3×10⁹Pa, particularly preferably 1.0 × 10⁸～1.3×10⁹Pa. by making the tensile modulus of elasticity less than 1.5 × 10⁹Pa, and thus a base film having a certain degree of rigidity is used, and the film easily follows curved portions and uneven portions of displays and the like, and is a preferred embodiment, the non-polyolefin film has a tensile elastic modulus of 1.5 × 10⁹When Pa is larger than Pa, the rigidity of the base film may become too strong to follow curved portions and uneven portions of a display, and this is not preferable.

The resin material constituting the base film may contain various additives such as an antioxidant, an ultraviolet absorber, a plasticizer, and a colorant (such as a pigment and a dye) as required. For example, a known or conventional surface treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and coating with a primer can be performed. Such a surface treatment may be, for example, a treatment for improving adhesion between the base film and the pressure-sensitive adhesive layer (anchoring property of the pressure-sensitive adhesive layer).

As the base film, a polyester film subjected to antistatic treatment may be used. The antistatic treatment may be applied to either the surface of the base film in contact with the adhesive layer or the surface of the base film not in contact with the adhesive layer. The use of the substrate film is preferable because electrification of the pressure-sensitive adhesive sheet (surface protective film) itself at the time of peeling can be suppressed. Further, the base film is a polyester film, and by applying antistatic treatment to the polyester film, electrification of the pressure-sensitive adhesive sheet (surface protective film) itself can be reduced, and antistatic ability to an adherend can be excellent. The method for imparting the antistatic function is not particularly limited, and conventionally known methods can be used, and examples thereof include a method of applying an antistatic resin composed of an antistatic agent and a resin component, a conductive polymer, a conductive resin containing a conductive substance, a method of vapor-depositing or plating a conductive substance, and a method of kneading an antistatic agent.

The thickness of the base film is usually about 5 to 200. mu.m, preferably about 8 to 150. mu.m, more preferably about 10 to 100. mu.m, and still more preferably about 13 to 100. mu.m. When the thickness of the base film is within the above range, the adhesion workability to an adherend, the releasability from an adherend, and the workability are excellent, and therefore, the base film is preferable.

< adhesive layer >

The pressure-sensitive adhesive sheet of the present invention is characterized by having a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive composition on one or both sides of a base film. The pressure-sensitive adhesive layer used in the present invention is not particularly limited as long as it is formed of a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive polymer having pressure-sensitive adhesiveness. As the adhesive composition, for example, an acrylic adhesive, a urethane adhesive, a synthetic rubber adhesive, a natural rubber adhesive, a silicone adhesive, a polyester adhesive, or the like can be used, and among them, at least 1 selected from the group consisting of an acrylic adhesive, a urethane adhesive, and a silicone adhesive is preferably used (contained), and particularly, an acrylic adhesive using a (meth) acrylic polymer as the adhesive polymer is preferably used.

< acrylic pressure-sensitive adhesive >

When an acrylic pressure-sensitive adhesive is used for the pressure-sensitive adhesive layer, a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms can be used as a main monomer as a raw material monomer for a (meth) acrylic polymer as a pressure-sensitive adhesive polymer constituting the acrylic pressure-sensitive adhesive. The (meth) acrylic monomer may be used in 1 kind or 2 or more kinds. By using the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, the peel strength (adhesive strength) to an adherend (protected object) can be easily controlled to be low, and a pressure-sensitive adhesive sheet (surface protective film) having excellent light peelability and removability can be obtained. In the present invention, the (meth) acrylic polymer refers to an acrylic polymer and/or a methacrylic polymer, and the (meth) acrylate refers to an acrylate and/or a methacrylate.

Specific examples of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate.

Among them, when the adhesive sheet of the present invention is used as a surface protective film, particularly, (meth) acrylic monomers having an alkyl group having 4 to 14 carbon atoms such as n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate can be cited as suitable examples. In particular, by using a (meth) acrylic monomer having an alkyl group having 4 to 14 carbon atoms, the peeling force (adhesive force) to an adherend can be easily controlled to be low, and the removability is excellent.

In particular, the (meth) acrylic monomer having an alkyl group with 1 to 14 carbon atoms is preferably contained in an amount of 40% by weight or more, more preferably 45% by weight or more, further preferably 45 to 99% by weight, and most preferably 50 to 98% by weight, based on 100% by weight of the total amount of the monomer components constituting the (meth) acrylic polymer. If the amount is outside the above range, the adhesive composition has an appropriate wettability and the cohesive force of the adhesive layer is undesirably deteriorated.

In addition, the (meth) acrylic polymer may use a hydroxyl group-containing (meth) acrylic monomer as a raw material monomer. As the hydroxyl group-containing (meth) acrylic monomer, 1 or 2 or more species can be used. By using the hydroxyl group-containing (meth) acrylic monomer, it becomes easy to control crosslinking and the like of the pressure-sensitive adhesive composition, and it becomes easy to control the balance between improvement of wettability by flow and reduction of peel strength (adhesive force) at the time of peeling.

Examples of the hydroxyl group-containing (meth) acrylic monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, 4-hydroxymethylcyclohexyl (meth) methyl acrylate, and N-methylol (meth) acrylamide.

The hydroxyl group-containing (meth) acrylic monomer is contained in an amount of preferably 20 wt% or less, more preferably 0.1 to 15 wt% or less, and still more preferably 1 to 10 wt% based on 100 wt% of the total amount of the monomer components constituting the (meth) acrylic polymer. When the amount is within the above range, it is easy to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the pressure-sensitive adhesive layer to be obtained, and therefore, this is preferable.

Further, as the other polymerizable monomer component, a polymerizable monomer for adjusting the glass transition temperature and the releasability of the (meth) acrylic polymer may be used so that the Tg is 0 ℃ or less (usually-100 ℃ or more) within the range not to impair the effect of the present invention, for the reason that the balance of the adhesive performance is easily obtained.

The (meth) acrylic polymer may use a carboxyl group-containing (meth) acrylic monomer as a raw material monomer. By using the carboxyl group-containing (meth) acrylic monomer, an increase in adhesive strength of the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet, surface protective film) with time can be suppressed, and the pressure-sensitive adhesive layer is excellent in removability, adhesion strength increase properties, and workability. In addition, the adhesive layer preferably has excellent cohesive force and excellent shear force.

Examples of the carboxyl group-containing (meth) acrylic monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, and carboxypentyl (meth) acrylate. In particular, the inclusion of acrylic acid as the carboxyl group-containing (meth) acrylic monomer increases the glass transition temperature (Tg) and improves the cohesive force, and for example, when the adhesive is applied to a curved surface such as a concave-convex surface or a curved portion, although the substrate has rigidity and thus springback occurs, the adhesive having high cohesive force is not easily deformed and has excellent repulsion resistance, and therefore, the adhesive is preferable.

The carboxyl group-containing (meth) acrylic monomer is preferably 20% by weight or less, more preferably 1 to 15% by weight, and still more preferably 2 to 12% by weight, based on 100% by weight of the total amount of the monomer components constituting the (meth) acrylic polymer. When the amount is within the above range, it is easy to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the pressure-sensitive adhesive layer to be obtained, and therefore, this is preferable.

Further, the (meth) acrylic polymer may be used without particular limitation as long as the characteristics of the present invention are not impaired, and other polymerizable monomers than the raw material monomers may be used. For example, as the other polymerizable monomer, a cohesive force/heat resistance-improving component such as a cyano group-containing monomer, a vinyl ester monomer, or an aromatic vinyl monomer, a component for improving a peeling force (adhesive force) such as an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, N-acryloylmorpholine, or a vinyl ether monomer, or a component having a functional group which functions as a crosslinking base point can be suitably used. Among them, nitrogen-containing monomers such as a cyano group-containing monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, and N-acryloylmorpholine are preferably used. The use of the nitrogen-containing monomer is useful because it can provide an adhesive sheet (surface protective film) which can secure an appropriate peeling force (adhesive force) and is excellent in shear force without causing lifting, peeling, or the like. These polymerizable monomers may be used in 1 kind or 2 or more kinds.

Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

Examples of the amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N-dimethylacrylamide, N-dimethylmethacrylamide, N-diethylacrylamide, N-diethylmethacrylamide, N' -methylenebisacrylamide, N-dimethylaminopropylacrylamide, N-dimethylaminopropylmethacrylamide, and diacetoneacrylamide.

Examples of the imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, and N, N-dimethylaminopropyl (meth) acrylate.

Examples of the vinyl ester monomer include vinyl acetate, vinyl propionate, and vinyl laurate.

Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethylstyrene, α -methylstyrene, and other substituted styrenes.

Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, methylglycidyl (meth) acrylate, and allyl glycidyl ether.

Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

In the present invention, the other polymerizable monomer is preferably 0 to 30% by weight, more preferably 0 to 10% by weight, based on 100% by weight of the total amount of the monomer components constituting the (meth) acrylic polymer. The other polymerizable monomers may be appropriately adjusted to obtain desired characteristics.

The (meth) acrylic polymer may further contain a reactive monomer containing an alkylene oxide (alkylene oxide) as a monomer component.

The average number of moles of oxyalkylene units added as the oxyalkylene-containing reactive monomer is preferably 1 to 40, more preferably 3 to 40, further preferably 4 to 35, and particularly preferably 5 to 30 from the viewpoint of compatibility with the oxyalkylene-containing compound. When the average addition mole number is 1 or more, the effect of reducing the contamination of an adherend (protected object) tends to be obtained efficiently. When the average addition mole number is more than 40, the interaction with the oxyalkylene-containing compound is large, and the viscosity of the adhesive composition tends to increase, whereby the application tends to be difficult, which is not preferable. The terminal of the oxyalkylene chain may be a hydroxyl group as it is, or may be substituted with another functional group or the like.

The oxyalkylene group-containing reactive monomer may be used alone or in combination of 2 or more, and the total content is preferably 0 to 20% by weight, more preferably 0 to 10% by weight, based on the total amount of the monomer components of the (meth) acrylic polymer. If the content of the oxyalkylene-containing reactive monomer exceeds 20% by weight, the staining property to an adherend is deteriorated, which is not preferable.

Examples of the oxyalkylene unit of the oxyalkylene group-containing reactive monomer include oxyalkylene units having an alkylene group having 1 to 6 carbon atoms, and examples thereof include oxymethylene, oxyethylene, oxypropylene, oxybutylene and the like. The hydrocarbon group of the oxyalkylene chain may be a straight chain or a branched chain.

Further, the oxyalkylene-containing reactive monomer is more preferably a reactive monomer having an oxyethylene group. By using a (meth) acrylic polymer containing a reactive monomer having an oxyethylene group as a base polymer, the compatibility of the base polymer with an oxyalkylene group-containing compound is improved, bleeding out to an adherend can be suitably suppressed, and a pressure-sensitive adhesive composition with low staining can be obtained.

Examples of the oxyalkylene group-containing reactive monomer include alkylene oxide adducts of (meth) acrylic acid, and reactive surfactants having a reactive substituent such as an acryloyl group, a methacryloyl group, or an allyl group in the molecule.

Specific examples of the (meth) acrylic acid alkylene oxide adduct include, for example, examples thereof include polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polybutylene glycol (meth) acrylate, polypropylene glycol-polybutylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, butoxypolyethylene glycol (meth) acrylate, octoxypolyethylene glycol (meth) acrylate, lauroxypolyethylene glycol (meth) acrylate, stearyloxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, and octoxypolyethylene glycol-polypropylene glycol (meth) acrylate.

Specific examples of the reactive surfactant include anionic reactive surfactants having a (meth) acryloyl group or allyl group, nonionic reactive surfactants, and cationic reactive surfactants.

The weight average molecular weight (Mw) of the (meth) acrylic polymer is preferably 10 to 200 ten thousand, more preferably 20 to 150 ten thousand, still more preferably 30 to 120 ten thousand, particularly preferably 30 to 100 ten thousand, and most preferably 40 to 80 ten thousand. When the weight average molecular weight is less than 10 ten thousand, the cohesive force of the adhesive layer tends to be small, and adhesive residue tends to occur. On the other hand, when the weight average molecular weight exceeds 200 ten thousand, the fluidity of the polymer decreases, the wetting with an adherend (for example, a polarizing plate) becomes insufficient, and the swelling tends to occur between the adherend and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (surface protective film). The weight average molecular weight is a value measured by GPC (gel permeation chromatography).

The glass transition temperature (Tg) of the (meth) acrylic polymer is preferably-60 to 0 ℃, more preferably-50 to-10 ℃. When the glass transition temperature is higher than 0 ℃, the polymer is less likely to flow, and for example, the wetting of the polarizing plate as an optical member becomes insufficient, which tends to cause swelling between the polarizing plate and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (surface protective film). When the glass transition temperature (Tg) is lower than-60 ℃, the cohesive force of the adhesive becomes low, and when the adhesive is attached to a curved surface such as a curve or an uneven surface, the adhesive layer tends to float because the adhesive layer cannot resist the repulsive force of the base material. By adjusting the glass transition temperature (Tg) to the above range, a pressure-sensitive adhesive layer having a balanced wettability and cohesive strength can be easily obtained. The glass transition temperature of the (meth) acrylic polymer can be adjusted to fall within the above range by appropriately changing the monomer components and the composition ratio to be used.

The polymerization method of the (meth) acrylic polymer is not particularly limited, and polymerization can be carried out by a known method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc., and solution polymerization is a more preferable mode particularly from the viewpoint of handling properties and characteristics such as low staining property to an adherend (protected object). The polymer obtained may be any of a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer, and the like.

< urethane-based pressure-sensitive adhesive >

When a urethane adhesive is used for the adhesive layer, any appropriate urethane adhesive can be used. As such a urethane adhesive, a urethane adhesive containing a urethane polymer as an adhesive polymer obtained by reacting a polyol with a polyisocyanate compound is preferable. Examples of the polyol include polyether polyol, polyester polyol, polycarbonate polyol, and polycaprolactone polyol. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, and hexamethylene diisocyanate.

< Silicone adhesive >

When a silicone adhesive is used for the adhesive layer, any suitable silicone adhesive can be used. As such a silicone adhesive, a silicone adhesive obtained by mixing or aggregating a silicone polymer as an adhesive polymer can be preferably used.

Examples of the silicone adhesive include an addition reaction curable silicone adhesive and a peroxide curable silicone adhesive. Among these silicone-based adhesives, addition reaction curing type silicone-based adhesives are preferred in that peroxides (e.g., benzoyl peroxide) are not used and decomposition products are not generated.

As the curing reaction of the addition reaction curing type silicone-based adhesive, for example, in the case of obtaining a polyalkylsilicone-based adhesive, a method of curing a polyalkylhydrosiloxane composition using a platinum catalyst is generally exemplified.

< oxyalkylene Compound >

The binder composition used in the present invention may further contain an oxyalkylene compound. By containing the oxyalkylene group-containing compound, further light peelability can be exhibited. Examples of the oxyalkylene group-containing compound include an organopolysiloxane having an oxyalkylene chain and an oxyalkylene group-containing compound containing no organopolysiloxane.

Specific examples of the organopolysiloxane having an oxyalkylene chain include commercially available products such as X-22-4952, X-22-4272, X-22-6266, KF-6004, KF-889 (manufactured BY shin-Etsu chemical Co., Ltd.), BY16-201, SF8427 (manufactured BY Dow Corning Toray Co., Ltd.), IM22 (manufactured BY AsahikaseiWacker), and the like. Further, examples of the organopolysiloxane having an oxyalkylene chain in a side chain include commercially available trade names KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6022, X-22-6191, X-22-4515, KF-6011, KF-6012, KF-6015, KF-6017, X-22-2516 (manufactured by shin-Etsu chemical Co., Ltd.), SF8428, FZ-2162, SH3749, FZ-77, L-7001, FZ-2104, FZ-2110, L-7002, FZ-2122, FZ-2164, FZ-2203, FZ-7001, SH8400, SH 848700, SF8410, and SF Town 22 (manufactured by Cor., Co., Ltd.), ltd, manufactured), TSF-4440, TSF-4441, TSF-4445, TSF-4450, TSF-4446, TSF-4452, TSF-4460 (manufactured by MomentivePerformance Materials Inc.), BYK-333, BYK-307, BYK-377, BYK-UV3500, BYK-UV3570 (manufactured by BYK Japan KK.), and the like. These compounds may be used alone, or 2 or more kinds thereof may be used in combination.

Specific examples of the oxyalkylene compound containing no organopolysiloxane include nonionic surfactants such as polyoxyalkylene alkylamines, polyoxyalkylene diamines, polyoxyalkylene fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene alkyl ethers, polyoxyalkylene alkylallyl ethers, and polyoxyalkylene alkylphenyl allyl ethers; anionic surfactants such as polyoxyalkylene alkyl ether sulfate ester salts, polyoxyalkylene alkyl ether phosphate ester salts, polyoxyalkylene alkyl phenyl ether sulfate ester salts, and polyoxyalkylene alkyl phenyl ether phosphate ester salts; and cationic surfactants having a polyoxyalkylene chain (polyalkylene oxide chain), zwitterionic surfactants, polyether compounds having a polyoxyalkylene chain (and derivatives thereof), acrylic compounds having a polyoxyalkylene chain (and derivatives thereof), and the like. In addition, a polyoxyalkylene chain-containing monomer may be compounded as the polyoxyalkylene chain-containing compound. The polyoxyalkylene chain-containing compound may be used alone, or 2 or more kinds thereof may be used in combination.

Specific examples of the polyether compound (polyether component) having a polyoxyalkylene chain include a polypropylene glycol (PPG) -polyethylene glycol (PEG) block copolymer, a PPG-PEG-PPG block copolymer, and a PEG-PPG-PEG block copolymer. Examples of the derivative of the polyether compound having a polyoxyalkylene chain include a compound having an oxypropylene group whose terminal is etherified (such as a PPG monoalkyl ether or a PEG-PPG monoalkyl ether), a compound having an oxypropylene group whose terminal is acetylated (such as a terminal-acetylated PPG), and the like.

Specific examples of the acrylic compound having a polyoxyalkylene chain include (meth) acrylate polymers having an oxyalkylene group. The oxyalkylene group is preferably an oxyalkylene unit having an addition mole number of1 to 50, more preferably 2 to 30, further preferably 2 to 20. The terminal of the oxyalkylene chain may be a hydroxyl group as it is, or may be substituted with an alkyl group, a phenyl group or the like.

As the monomer component of the (meth) acrylate polymer having an oxyalkylene group, a polymer containing an alkylene oxide of (meth) acrylate is preferable, and as specific examples of the alkylene oxide of (meth) acrylate, examples of the ethylene glycol group-containing (meth) acrylate include methoxy-polyethylene glycol (meth) acrylate such as methoxy-diethylene glycol (meth) acrylate and methoxy-triethylene glycol (meth) acrylate, ethoxy-polyethylene glycol (meth) acrylate such as ethoxy-diethylene glycol (meth) acrylate and ethoxy-triethylene glycol (meth) acrylate, butoxy-diethylene glycol (meth) acrylate such as butoxy-triethylene glycol (meth) acrylate, butoxy-polyethylene glycol (meth) acrylate, and the like, Phenoxy-polyethylene glycol (meth) acrylate types such as phenoxy-diethylene glycol (meth) acrylate and phenoxy-triethylene glycol (meth) acrylate, methoxy-polypropylene glycol (meth) acrylate types such as 2-ethylhexyl-polyethylene glycol (meth) acrylate, nonylphenol-polyethylene glycol (meth) acrylate, and methoxy-dipropylene glycol (meth) acrylate, and the like.

Further, as the monomer component, other monomer components than the alkylene oxide of (meth) acrylic acid may be used. Specific examples of the other monomer component include acrylic esters and/or methacrylic esters having an alkyl group having 1 to 14 carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate.

Further, as other monomer components other than the above-mentioned alkylene oxide of (meth) acrylate, a carboxyl group-containing (meth) acrylate, a phosphoric group-containing (meth) acrylate, a cyano group-containing (meth) acrylate, a vinyl ester, an aromatic vinyl compound, an acid anhydride group-containing (meth) acrylate, a hydroxyl group-containing (meth) acrylate, an amide group-containing (meth) acrylate, an amino group-containing (meth) acrylate, an epoxy group-containing (meth) acrylate, N-acryloylmorpholine, vinyl ethers, and the like can be suitably used.

< crosslinking agent >

In the adhesive sheet of the present invention, the adhesive composition preferably contains a crosslinking agent. In the present invention, the adhesive layer may be formed using the adhesive composition. For example, in the case of an acrylic pressure-sensitive adhesive containing the (meth) acrylic polymer, the pressure-sensitive adhesive composition can be crosslinked by appropriately adjusting the constituent units and the constituent ratio of the (meth) acrylic polymer, the selection and addition ratio of the crosslinking agent, and the like, thereby obtaining a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet, surface-protecting film) having more excellent heat resistance and conformability to curved surfaces such as curved portions and uneven portions.

As the crosslinking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine derivative, a metal chelate compound, and the like can be used, and particularly when an epoxy compound is used, the cohesive force of the adhesive is increased, which is a preferable embodiment. These compounds may be used alone or in combination of 2 or more.

As the aforementioned isocyanate compound, for example, examples thereof include aliphatic polyisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, Hexamethylene Diisocyanate (HDI) and dimer acid diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI) and 1, 3-bis (isocyanatomethyl) cyclohexane, aromatic isocyanates such as 2, 4-toluene diisocyanate, 4' -diphenylmethane diisocyanate and Xylylene Diisocyanate (XDI), and modified polyisocyanates obtained by modifying the isocyanate compounds with allophanate bond, biuret bond, isocyanurate bond, uretdione bond, urea bond, carbodiimide bond, uretonimine bond and oxadiazinetrione bond. For example, commercially available products include trade names of Takenate 300S, TAKENATE500, Takenate 600, TAKENATE D165N, TAKENATE D178N (manufactured by Mitsui chemical Co., Ltd.), Sumidur T80, Sumidur L, Desmodur N3400 (manufactured by Sumika Bayer Urethane Co., Ltd.), Millionate MR, Millionate MT, CORONATE L, CORONATE HL, CORONATE HX (manufactured by Tosoh Co., Ltd.), and the like. These isocyanate compounds may be used alone, or 2 or more kinds may be used in combination, or a 2-functional isocyanate compound and a 3-functional isocyanate compound may be used in combination. By using a crosslinking agent in combination, an adhesive layer (adhesive sheet, surface protective film) having both adhesion and repulsion resistance (adhesion to curved surfaces such as curved portions and uneven portions) and more excellent adhesion reliability can be obtained.

Examples of the epoxy compound include N, N, N ', N' -tetraglycidyl m-xylylenediamine (trade name TETRAD-X, manufactured by Mitsubishi gas chemical Co., Ltd.), 1, 3-bis (N, N-diglycidylaminomethyl) cyclohexane (trade name TETRAD-C, manufactured by Mitsubishi gas chemical Co., Ltd.), and the like.

Examples of the melamine resin include hexamethylolmelamine. Examples of aziridine derivatives include commercially available products such as HDU, TAZM and TAZO (manufactured by CRKOKAI Co., Ltd.).

Examples of the metal chelate include aluminum, iron, tin, titanium, nickel and the like as the metal component, and examples of the chelate include acetylene, methyl acetoacetate, ethyl lactate and the like.

The content of the crosslinking agent used in the present invention is, for example, preferably 0.01 to 20 parts by weight, more preferably 0.1 to 18 parts by weight, still more preferably 0.5 to 15 parts by weight, and most preferably 1 to 12 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer. When the content is less than 0.01 part by weight, the crosslinking formation by the crosslinking agent may be insufficient, the cohesive force of the obtained pressure-sensitive adhesive layer may be small, and sufficient heat resistance may not be obtained, and the adhesive may cause residual glue and the repulsion resistance at the time of bonding to a curved surface such as a curved portion or an uneven portion may be poor. On the other hand, when the content exceeds 20 parts by weight, the cohesive force of the polymer is large, the fluidity is lowered, and the wetting with an adherend (for example, a polarizing plate) becomes insufficient, and thus it tends to cause swelling between the adherend and the pressure-sensitive adhesive layer (pressure-sensitive adhesive composition layer). In addition, by using a crosslinking agent in the above range, a balance between wettability and repulsion resistance can be obtained, and a pressure-sensitive adhesive layer excellent in followability to a bent portion and a concave-convex portion can be easily obtained, which is a preferable embodiment. These crosslinking agents may be used alone, or 2 or more kinds thereof may be used in combination.

< crosslinking catalyst >

The pressure-sensitive adhesive composition may further contain a crosslinking catalyst for allowing any of the above crosslinking reactions to proceed more efficiently. Examples of the crosslinking catalyst include tin catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, iron tris (acetylacetonate), iron tris (hexane-2, 4-dione), iron tris (heptane-3, 5-dione), iron tris (5-methylhexane-2, 4-dione), iron tris (octane-2, 4-dione), iron tris (6-methylheptane-2, 4-dione), iron tris (2, 6-dimethylheptane-3, 5-dione), iron tris (nonane-2, 4-dione), iron tris (nonane-4, 6-dione), iron tris (2,2,6, 6-tetramethylheptane-3, 5-dione), iron tris (tetrakis-2, 4-dione), iron (tetrakis-ethyl-, Tris (tridecane-6, 8-dione) iron, tris (1-phenylbutane-1, 3-dione) iron, tris (hexafluoroacetylacetonato) iron, tris (acetoacetoxyethyl) iron, tris (acetoacetoxy-n-propyl) iron, tris (acetoacetoxy-isopropyl) iron, tris (acetoacetoxy-n-butyl) iron, tris (acetoacetoxy-sec-butyl) iron, tris (acetoacetoxy-tert-butyl) iron, tris (propionylacetoacetomethyl) iron, tris (propionylacetoacetoethyl) iron, tris (propionylacetoaceto-n-propyl) iron, tris (propionylacetoaceto-isopropyl) iron, tris (propionylacetoaceto-n-butyl) iron, tris (propionylacetoaceto-sec-butyl) iron, tris (propionylacetoaceto-tert-butyl) iron, tris (acetoacetoxy-benzyl) iron, tris (malonic acid dimethyl) iron, tris (malonic acid, dimethyl) iron, tris, Iron-based catalysts such as tris (diethyl malonate) iron, trimethoxy iron, triethoxy iron, triisopropoxy iron, and ferric chloride. These crosslinking catalysts may be used in 1 kind, or 2 or more kinds may be used in combination.

The content of the crosslinking catalyst is not particularly limited, and is, for example, preferably about 0.0001 to 1 part by weight, more preferably 0.001 to 0.5 part by weight, based on 100 parts by weight of the (meth) acrylic polymer. When the content is within the above range, the crosslinking reaction speed at the time of forming the pressure-sensitive adhesive layer is high, and the pot life of the pressure-sensitive adhesive composition is also prolonged, which is a preferable embodiment.

The pressure-sensitive adhesive composition may contain other known additives, and for example, powders such as lubricants, colorants and pigments, plasticizers, tackifiers, low-molecular weight polymers, surface lubricants, leveling agents, antioxidants, anticorrosive agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, antistatic agents, inorganic or organic fillers, metal powders, pellets, foils, and the like may be added as appropriate depending on the application.

< pressure-sensitive adhesive sheet (surface protective film) >

The pressure-sensitive adhesive sheet (surface-protecting film) of the present invention is characterized by having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition on one side or both sides of a base film, and in this case, the pressure-sensitive adhesive composition is usually crosslinked after application of the pressure-sensitive adhesive composition, and the pressure-sensitive adhesive layer formed from the crosslinked pressure-sensitive adhesive composition may be transferred to the base film or the like.

The method for forming the pressure-sensitive adhesive layer on the base film is not particularly limited, and for example, the pressure-sensitive adhesive layer is formed on the base film by applying the pressure-sensitive adhesive composition (solution) to the base film and drying and removing the polymerization solvent or the like. Further, the curing may be performed for the purpose of adjusting the component transfer of the pressure-sensitive adhesive layer, adjusting the crosslinking reaction, or the like. In the case of producing a pressure-sensitive adhesive sheet by applying the pressure-sensitive adhesive composition to a base film, one or more solvents other than the polymerization solvent may be newly added to the pressure-sensitive adhesive composition so as to be uniformly applied to the base film.

In addition, as a method for forming the pressure-sensitive adhesive layer in the production of the pressure-sensitive adhesive sheet of the present invention, a known method used in the production of pressure-sensitive adhesive tapes can be used. Specific examples thereof include roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, extrusion coating using a die coater, and the like.

The adhesive sheet of the present invention is generally produced by: the thickness of the adhesive layer is 3 to 100 μm, preferably about 5 to 30 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, a proper balance between removability and adhesiveness is easily obtained, which is preferable.

The total thickness of the adhesive sheet of the present invention is preferably 8 to 300. mu.m, more preferably 10 to 200. mu.m, and most preferably 20 to 100. mu.m. When the content is within the above range, the adhesive properties (removability, adhesiveness, etc.), handling properties, and appearance properties are excellent, and a preferable embodiment is obtained. The total thickness is the sum of the thicknesses of all layers including the base film, the adhesive layer, the separator, and other layers.

< separator >

The pressure-sensitive adhesive sheet disclosed herein may be in the form of a pressure-sensitive adhesive article in which a separator (release liner) is bonded to the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface. Therefore, according to the specification, a spacer-attached adhesive sheet (adhesive article) comprising any of the adhesive sheets disclosed herein and a spacer for protecting the adhesive surface of the adhesive sheet can be provided.

The separator is not particularly limited, and for example, a separator having a release layer on a surface of a base material such as a resin film or paper (which may be laminated with a resin such as polyethylene); and separators obtained from resin films formed from low-adhesion materials such as fluorine-based polymers (polytetrafluoroethylene, etc.) and polyolefin-based resins (polyethylene, polypropylene, etc.). From the viewpoint of excellent surface smoothness, a separator having a release layer on the surface of a resin film as a base material or a separator obtained from 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 a polyethylene film, a polypropylene film, a polybutylene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyester film (a PET film, a PBT film, and the like), a polyurethane film, and an ethylene-vinyl acetate copolymer film. For example, a known release treatment agent such as a silicone release treatment agent, a long-chain alkyl release treatment agent, an olefin release treatment agent, a fluorine release treatment agent, a fatty acid amide release treatment agent, molybdenum sulfide, or silica powder can be used to form the release layer. Particularly, a silicone-based release treating agent is preferably used. The thickness of the release agent is not particularly limited, but is usually preferably about 0.01 to 1 μm, more preferably about 0.1 to 1 μm.

The thickness of the separator is not particularly limited, but is usually about 5 to 200 μm (e.g., about 10 to 100 μm, preferably about 20 to 80 μm) as appropriate. When the thickness of the separator is within the above range, the workability of bonding to the adhesive layer and the workability of peeling from the adhesive layer are excellent, and therefore, the thickness is preferable.

The substrate for a separator may be subjected to various surface treatments such as corona discharge treatment and various surface treatments such as embossing, if necessary. In addition, various additives such as fillers (inorganic fillers, organic fillers, and the like), antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, colorants (pigments, dyes, and the like), and the like may be added as necessary.

The surface of the separator to which the release treatment agent is applied or the surface to which the release treatment agent is not applied may be subjected to antistatic treatment.

The pressure-sensitive adhesive sheet (surface protective film) disclosed herein may be implemented so as to include other layers in addition to the base film, the pressure-sensitive adhesive layer, and the separator. Examples of the other layer include an antistatic layer and an undercoat layer (anchor layer) for improving the anchoring property of the adhesive layer.

The adhesive sheet of the present invention is characterized in that the vertical sagging distance L when the adhesive sheet is cut to a width of 50mm and a length of 100mm and fixed on a horizontal table so as to exceed 50mm in the longitudinal direction is 30mm or more, and the peeling force (low-speed peeling force) when the adhesive layer is surface-bonded to glass and stretched at a peeling speed of1 mm/min in the 90-degree direction is 3.0gf/50mm or more. When the vertical sagging distance L is 30mm or more, a base film having low rigidity is used as the base film, and therefore, when the film is adhered to a curved surface such as a curved portion or a concave-convex portion, the base film has low springback and good conformability, which is preferable. Further, since the cohesive force of the pressure-sensitive adhesive increases as the low-speed peeling force increases, the repulsion resistance when the pressure-sensitive adhesive is bonded to a curved surface such as a curved portion or an uneven portion is excellent, and the adhesiveness to the curved surface is excellent. In particular, it is preferable that the low-speed peeling force is 3.0gf/50mm or more, so that the adhesive sheet can be adhered to a curved surface such as a curved portion or a concave-convex portion without causing floating. The vertical hanging distance L is preferably 32mm or more, more preferably 32 to 50mm, and further preferably 34 to 49 mm. The peeling force is preferably 4gf/50mm or more, more preferably 6 to 30gf/50mm, and still more preferably 8 to 15gf/50 mm. When the upper limit value of the peeling force is 30gf/50mm or less, the peeling force (adhesive force) is not excessively high, and the removability is excellent, which is a preferable embodiment.

< optical Member >

The optical member of the present invention is preferably protected by the adhesive sheet. In the present invention, the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (surface protective film) may be bonded to an optical member to protect the optical member. Further, since the following ability to the curved portion and the uneven portion is good, it is useful for protecting the surface of the optical member having the curved portion and the uneven portion.

< display device >

The display device of the present invention is preferably protected by the adhesive sheet. In the present invention, the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (surface protective film) may be bonded to the surface of a display device or a display (screen) constituting the display device to protect the display device or the display. Further, since the surface-protecting film has good conformability to the curved portion and the uneven portion, it is useful for protecting the surface of a display device or a display having the curved portion and the uneven portion.