KR20200067250A - Surface protecting film and optical member - Google Patents

Abstract

The present invention relates to a surface protection film which can be easily peeled off at a stage where the surface protection film is unnecessary for a thin optical member or a display panel by using the surface protection film using an adhesive layer of a specific thickness, a surface protection, and to an optical member protected by the surface protection film. The surface protection film of the present invention is formed of the adhesive layer on at least one side of a base film and the base film, wherein the thickness of the adhesive layer is less than 2 μm.

Description

Surface protective film and optical member {SURFACE PROTECTING FILM AND OPTICAL MEMBER}

The present invention relates to a surface protection film and an optical member. In particular, polarizing films used in liquid crystal displays, organic EL displays, touch panel displays, etc., wavelength plates, retardation plates, optical compensation films, reflective sheets, brightness enhancing films, cover glasses, cover sheets, hard coat films, transparent conductive glass, transparent It is useful as a surface protection film used for the purpose of protecting the surface of an optical member such as a conductive film.

Background Art In recent years, optical display panels such as liquid crystal displays, organic EL displays, and touch panel displays have been thinned in terms of design and portability, and there is a demand for thinning of optical members used in the displays.

On the other hand, by using such a thin optical member, there is a problem in handling during the manufacturing process, and a countermeasure is required. For example, in the manufacture of a liquid crystal display panel, a polarizing film bonded to a liquid crystal cell is once formed in a roll form, then unwound from this roll and formed by bonding to a liquid crystal cell, or desired according to the shape of the liquid crystal cell. It is formed by cutting to size and then bonding to a liquid crystal cell. In addition, the polarizing film is bonded with a surface protection film for the purpose of preventing scratches and contamination occurring during transportation (Patent Document 1).

The surface protection film is removed by being peeled off at an unnecessary step, but when the liquid crystal display panel is thin, when the surface protection film having a high peeling force is peeled off, the liquid crystal display bends and the surface protection film cannot be peeled satisfactorily. In some cases, problems may occur, such as destruction of a liquid crystal display panel or a polarizing film when peeling.

Japanese Patent Publication No. 2001-305346

Thus, in view of the above circumstances, the present invention has been studied in earnest, and by using a surface protection film using a pressure-sensitive adhesive layer of a specific thickness, it is easy to obtain a thin optical member or display panel at a stage where a surface protection film is unnecessary. It is an object to provide a surface protective film capable of peeling and an optical member protected by the surface protective film.

That is, the surface protection film of the present invention is characterized in that the thickness of the pressure-sensitive adhesive layer is less than 2 μm in the surface protection film formed by forming the pressure-sensitive adhesive layer on at least one side of the base film and the base film.

It is preferable that the surface protection film of the present invention has a peeling force of 90° peel gauge at 50%RH at 23°C for the triacetylcellulose film of 1 N/50 mm or less.

It is preferable that the thickness of the said base film is 20 micrometers or more in the surface protection film of this invention.

It is preferable that the surface protection film of this invention contains at least 1 sort(s) selected from the group which the said adhesive layer consists of acrylic adhesive, urethane adhesive, and silicone adhesive.

It is preferable that the optical member of the present invention is protected by the surface protection film.

It is preferable that the optical member of this invention is a polarizing film which the said optical member contains a polarizer, and the thickness of the said polarizer is 8 micrometers or less.

The present invention is useful because by using a surface protection film having a pressure-sensitive adhesive layer of a specific thickness, after attaching to a thin optical member or display panel, the surface protection film can be easily peeled off at an unnecessary step.

1 is a schematic cross-sectional view showing a configuration example in which the surface protection film according to the present invention is attached to a polarizing film.
It is explanatory drawing which shows the measuring method of the instrument peeling force.

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

<Overall structure of the surface protection film>

The surface protection film disclosed herein is generally of a type called an adhesive sheet, an adhesive tape, an adhesive label, an adhesive film, and the like, and in particular, an optical member (for example, a liquid crystal display panel component such as a polarizing film, a wave plate, etc.) It is suitable as a surface protection film which protects the surface of an optical member during processing or conveyance of an optical member used as, or an optical member used in a touch panel display such as a hard coat film). Although the adhesive layer in the said surface protection film is typically formed continuously, it is not limited to this form, For example, the adhesive layer formed in the regular or random pattern, such as a dot shape and a stripe shape, may be sufficient. In addition, the surface protection film disclosed herein may be in the form of a roll or a single sheet.

A typical configuration example of the surface protection film disclosed herein is schematically illustrated in FIG. 1. This surface protection film 1 includes a base film (for example, a polyester film) 12 and an adhesive layer 20 provided on one side of the base film 12. The surface protection film 1 is used by attaching the pressure-sensitive adhesive layer 20 to an adherend (protection target, for example, the surface of the transparent protection film 30 that is the surface of an optical member such as a polarizing film). The surface protective film 1 before use (i.e., before adhesion to the adherend) is a separator (the surface of the pressure-sensitive adhesive layer 20 (the adhesion surface to the adherend), and at least the pressure-sensitive adhesive layer 20 side is a release surface ( It may be a form protected by a release liner). Alternatively, when the surface protection film 1 is wound in a roll shape, the pressure-sensitive adhesive layer 20 may be in contact with the back surface of the base film 12, and the surface may be protected.

In addition, as shown in FIG. 1, through the pressure-sensitive adhesive layer 20 constituting the surface protection film 1, it is attached to the surface of the transparent protection film 30 constituting the polarizing film 2, and the polarizing film ( 2) can be protected. In addition, the transparent protective film 30 and the polarizer 40 may form a polarizing film through the adhesive layer 22. In addition, a transparent protective film 31 is attached to the surface opposite to the surface of the polarizer 40 on which the transparent protective film 30 is attached, through the adhesive layer 23, and further, the first adhesive layer. (21) can be laminated, and other optical members or the like can also be laminated through this.

<Base film of surface protection film>

The surface protection film of the present invention is characterized by having a base film. In the technique disclosed herein, the resin material constituting the base film can be used without particular limitation, but has excellent properties such as transparency, mechanical strength, thermal stability, moisture shielding property, isotropy, flexibility, and dimensional stability, for example. It is preferred to use. In particular, when the base film has flexibility, the pressure-sensitive adhesive composition can be applied by a roll coater or the like, and can be wound in a roll shape, which is useful.

As the base film (substrate, support), for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyester-based polymers such as polybutylene terephthalate; Cellulose polymers such as diacetyl cellulose and triacetyl cellulose; Polycarbonate polymers; Acrylic polymers such as polymethyl methacrylate; A plastic film made of a resin material whose main component is a main resin component (main component in a resin component, typically 50 mass% or more) can be preferably used as the base film. Other examples of the resin material include styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers; Olefin polymers such as polyethylene, polypropylene, polyolefins having a cyclic to norbornene structure, and ethylene-propylene copolymers; Vinyl chloride polymers; Amide-based polymers such as nylon 6, nylon 6, 6, and aromatic polyamides; And the like made of a resin material. As another example of the resin material, imide polymer, sulfone polymer, polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl booty And ral polymers, arylate polymers, polyoxymethylene polymers, and epoxy polymers. A base film made of two or more blends of the above-described polymers may be used.

A plastic film made of a transparent thermoplastic resin material can be preferably used as the base film. Among the plastic films, it is more preferable to use a polyester film. Here, the polyester film is a polymer material (polyester resin) having a main skeleton based on ester bonds such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate as the main resin component. Say something. Such a polyester film is preferable as a base film of a surface protection film, such as having excellent optical properties and dimensional stability.

Various additives, such as an antistatic agent, an antioxidant, an ultraviolet absorber, a plasticizer, and a coloring agent (pigment, dye, etc.) may be mix|blended with the resin material which comprises the said base film as needed. For example, known or conventional surface treatments, such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and application of a primer, may be performed. Such a surface treatment may be, for example, a treatment for increasing the adhesion between the base film and the pressure-sensitive adhesive layer (adhesiveness of the pressure-sensitive adhesive layer).

The surface protection film of the present invention, as the base film, it is also possible to use a plastic film made of an antistatic treatment. By using the base film, charging of the surface protective film itself at the time of peeling is suppressed, which is preferable. In addition, the base film is a plastic film, and by subjecting the plastic film to an antistatic treatment, it is possible to reduce the charge of the surface protection film itself and to obtain an excellent antistatic property to the adherend. The method for imparting an antistatic function is not particularly limited, and a conventionally known method can be used. For example, an antistatic resin comprising an antistatic agent and a resin component, an electrically conductive polymer, or an electrically conductive resin containing a conductive material And a method of coating or depositing or plating a conductive material, a method of mixing an antistatic agent, and the like.

The thickness of the base film is preferably 20 μm or more, more preferably 20 to 200 μm, further preferably 25 to 150 μm, particularly preferably 30 to 100 μm, and most preferably 50 to 80 Μm. When the thickness of the base film is within the above range, the transportability and bonding workability of the polarizing film or the optical member are improved, which is preferable. Particularly, when used for a thin optical member having a thickness of 100 µm or less, a thickness of 50 µm or more is preferably used as the thickness of the base film in order to ensure conveyability and bonding workability.

In addition to the base film and the pressure-sensitive adhesive layer, the surface protection film disclosed herein can also be implemented in a form including another layer. Examples of the other layer include a primer layer (anchor layer) or the like that enhances anchorability of an antistatic layer or an adhesive layer.

<Adhesive layer of surface protection film>

The surface protection film of the present invention has a pressure-sensitive adhesive layer on at least one side of the base film, and the pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition can be used without particular limitation, as long as it has pressure-sensitive adhesive properties. As the above-mentioned pressure-sensitive adhesive composition, for example, an acrylic pressure-sensitive adhesive, a urethane-based pressure sensitive adhesive, a synthetic rubber pressure-sensitive adhesive, a natural rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a polyester pressure-sensitive adhesive, a polyether-based pressure-sensitive adhesive, etc. can be used (containing), and more preferably, Is at least one selected from the group consisting of acrylic adhesives, urethane-based adhesives, and silicone-based adhesives, and particularly preferably (containing) an acrylic adhesive using a (meth)acrylic polymer that is an adhesive polymer.

<Acrylic adhesive>

When the pressure-sensitive adhesive layer uses an acrylic pressure-sensitive adhesive, the (meth)acrylic polymer, which is an adhesive polymer constituting the acrylic pressure-sensitive adhesive, is a raw material monomer constituting this, and a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms is mainly used. It can be used as a monomer. As said (meth)acrylic-type monomer, 1 type(s) or 2 or more types can be used. By using the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms, it is easy to control the peeling force (adhesive force) to the adherend (protected body) low, and the surface is excellent in light peeling property and removability. A protective film is obtained. In addition, (meth)acrylic-type polymer in this invention means an acryl-type polymer and/or methacryl-type polymer, and (meth)acrylate means acrylate and/or methacrylate.

Specific examples of the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and s-butyl (meth). Acrylate, t-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, n-tetradecyl (meth)acrylate, etc. are mentioned.

Especially, as a surface protection film of this invention, 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- Suitable (meth)acrylic monomers having an alkyl group having 4 to 14 carbon atoms, such as tridecyl (meth)acrylate and n-tetradecyl (meth)acrylate, are mentioned. In particular, by using a (meth)acrylic monomer having an alkyl group having 6 to 14 carbon atoms, it is easy to control the peeling force (adhesive force) to the adherend to be low, and it becomes an excellent re-release property.

In particular, it is preferable to contain 50 mass% or more of (meth)acrylic monomers having an alkyl group having 1 to 14 carbon atoms with respect to 100 mass% of the total amount of monomer components constituting the (meth)acrylic polymer, more preferably 80 It is more than mass%, more preferably 85 to 99.9 mass%, and most preferably 90 to 99 mass%. When it is less than 50% by mass, the appropriate wettability of the pressure-sensitive adhesive composition or the cohesive force of the pressure-sensitive adhesive layer is reduced, which is not preferable.

Moreover, it is preferable that the said (meth)acrylic-type polymer contains the hydroxyl group containing (meth)acrylic-type monomer as a raw material monomer in the adhesive composition of this invention. As said hydroxyl group containing (meth)acrylic-type monomer, 1 type(s) or 2 or more types can be used. By using the hydroxyl group-containing (meth)acrylic monomer, it becomes easy to control crosslinking of the pressure-sensitive adhesive composition, and further improves the wettability due to flow and controls the balance of reduction in peeling force (adhesive power) in peeling. It becomes easy.

Examples of the hydroxyl group-containing (meth)acrylic monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6- Hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclo Hexyl)methyl acrylate, N-methylol (meth)acrylamide, and the like. In particular, by using a hydroxyl group-containing (meth)acrylic monomer having 4 or more carbon atoms in the alkyl group, light peeling during high-speed peeling is facilitated, which is preferable.

It is preferable to contain the said hydroxyl group-containing (meth)acrylic-type monomer 25 mass% or less with respect to 100 mass% of the monomer component which comprises the said (meth)acrylic-type polymer, More preferably, it is 20 mass% or less, further It is preferably 0.1 to 15% by mass, and most preferably 1 to 10% by mass. It is preferable that it is in the said range, since it is easy to control the balance of the wettability of an adhesive composition and the cohesive force of the adhesive layer obtained.

In addition, for other polymerizable monomer components, Tg is set to 0° C. or lower (normally −100° C. or higher), and the glass transition temperature or peelability of the (meth)acrylic polymer is adjusted for reasons that the adhesion performance is easily balanced. Polymerizable monomers for the purpose of being used can be used within a range that does not impair the effects of the present invention.

Examples of the (meth)acrylic monomer having the alkyl group having 1 to 14 carbon atoms and other polymerizable monomers other than the hydroxyl group-containing (meth)acrylic monomer used in the (meth)acrylic polymer include a carboxyl group-containing (meth)acrylic system Monomers can be used. By using the carboxyl group-containing (meth)acrylic monomer, it is possible to suppress an increase in the adhesive strength over time of the surface protective film (adhesive layer), excellent re-removability, adhesive strength increase prevention and workability, and also an adhesive layer The cohesive force of is excellent as well as the shearing force.

Examples of the carboxyl group-containing (meth)acrylic monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, and carboxylpentyl (meth)acrylate.

The (meth)acrylic monomer containing the carboxyl group is preferably 10% by mass or less, more preferably 0.005 to 10% by mass, and more preferably 0.01 to 8% by mass of 100% by mass of the monomer components constituting the (meth)acrylic polymer. It is more preferable that it is a mass %, and 0.01-5 mass% is most preferable. It is preferable that it is in the said range, since it is easy to control the balance of the wettability of an adhesive composition and the cohesive force of the adhesive layer obtained.

Further, other polymerizable polymers other than the (meth)acrylic monomers having an alkyl group having 1 to 14 carbon atoms, hydroxyl group-containing (meth)acrylic monomers and carboxyl group-containing (meth)acrylic monomers used in the (meth)acrylic polymer. As a monomer, if it is in the range which does not impair the characteristics of the present invention, it can be used without particular limitation. For example, components that improve cohesion and heat resistance, such as cyano group-containing monomers, vinyl ester monomers, and aromatic vinyl monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, and N-acryloyl morpholine , A component having a functional group serving as a starting point for crosslinking such as a vinyl ether monomer can be suitably used. Among them, it is preferable to use a nitrogen-containing monomer such as a cyano group-containing monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, and N-acryloyl morpholine. The use of a nitrogen-containing monomer is useful because it is possible to further obtain a surface protective film having excellent shear force. One kind or two or more kinds of these polymerizable monomers can be used.

As said cyano group containing monomer, acrylonitrile and methacrylonitrile are mentioned, for example.

Examples of the amide group-containing monomers include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, and N,N-. Diethylacrylamide, N,N-diethylmethacrylamide, N,N'-methylenebisacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, diacetone acrylamide And the like.

Examples of the imide group-containing monomers include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itacimide.

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

As said vinyl ester monomer, vinyl acetate, vinyl propionate, vinyl laurate, etc. are mentioned, for example.

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

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

As said vinyl ether monomer, methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, etc. are mentioned, for example.

In the present invention, other polymerizable monomers other than the (meth)acrylic monomer having a alkyl group having 1 to 14 carbon atoms, the hydroxyl group-containing (meth)acrylic monomer, and the carboxyl group-containing (meth)acrylic monomer are the (meth)acrylic polymers. It is preferable that it is 0-50 mass% with respect to 100 mass% of all monomer component which comprises, and it is more preferable that it is 0-20 mass %. The other polymerizable monomers can be appropriately adjusted to obtain desired properties.

The (meth)acrylic polymer may further contain an alkylene oxide group-containing reactive monomer as a monomer component. By using the said monomer, it becomes easy to achieve the cohesion of adhesiveness and peelability to an adherend.

The (meth)acrylic polymer has a weight average molecular weight (Mw) of preferably 100,000 to 3,000,000, more preferably 200,000 to 2,000,000, more preferably 300,000 to 95,000, most preferably 300,000 to 75 It is only. When the weight average molecular weight is less than 100,000, the cohesive force of the pressure-sensitive adhesive layer tends to decrease, resulting in the occurrence of pressure-sensitive adhesive residue. On the other hand, when the weight average molecular weight exceeds 3 million, the fluidity of the polymer decreases, wetting with an adherend (for example, a polarizing film) becomes insufficient, and expansion occurs between the adherend and the pressure-sensitive adhesive layer of the surface protection film. There is a tendency to cause. In addition, the weight average molecular weight means what was obtained by measuring by GPC (gel permeation chromatography).

Further, the glass transition temperature (Tg) of the (meth)acrylic polymer is preferably 0°C or lower, more preferably -10°C or lower (normally -100°C or higher). When the glass transition temperature is higher than 0°C, the polymer is difficult to flow, for example, the wetting with a polarizing film becomes insufficient, and there is a tendency to cause expansion occurring between the polarizing film and the pressure-sensitive adhesive layer of the surface protection film. In particular, by setting the glass transition temperature to -50°C or less, an adhesive layer excellent in wettability and light peelability to a polarizing film is easily obtained. Further, the glass transition temperature of the (meth)acrylic polymer can be adjusted within the above range by appropriately changing the monomer component or composition ratio used.

The method for polymerizing the (meth)acrylic polymer is not particularly limited, and can be polymerized by known methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. From the viewpoint of characteristics such as low contamination with a sieve), solution polymerization is a more preferable form. Further, the polymer obtained may be any of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer.

<Urethane adhesive>

When a urethane-based adhesive is used for the pressure-sensitive adhesive layer, any suitable urethane-based adhesive can be employed. As such a urethane-type adhesive, what consists of urethane-type polymer which is an adhesive polymer obtained by making polyol and a polyisocyanate compound react preferably is mentioned. As polyol, polyether polyol, polyester polyol, polycarbonate polyol, polycaprolactone polyol, etc. are mentioned, for example. As a polyisocyanate compound, diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, etc. are mentioned, for example.

<Silicone-based adhesive>

When a silicone adhesive is used for the adhesive layer, any suitable silicone adhesive can be employed. As such a silicone-based adhesive, one obtained by blending or agglomerating a silicone-based polymer that is preferably an adhesive polymer can be employed.

Moreover, as said silicone type adhesive agent, an addition reaction hardening type silicone type adhesive agent and a peroxide curing type silicone type adhesive agent are mentioned. Among these silicone-based adhesives, an addition reaction-curable silicone-based adhesive is preferred from the viewpoint that no decomposition products are generated without using peroxides (benzoyl peroxide).

As a hardening reaction of the said addition reaction hardening type silicone adhesive, when obtaining a polyalkyl silicone adhesive, for example, the method of hardening a polyalkyl hydrogen siloxane composition with a platinum catalyst is mentioned generally.

<Crosslinking system>

It is preferable that the said adhesive composition contains the crosslinking agent in the surface protection film of this invention. Moreover, in this invention, using the said adhesive composition, it can be set as an adhesive layer. For example, in the case where the pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive containing the (meth)acrylic polymer, crosslinking is performed by appropriately adjusting the structural units, composition ratio, selection and addition ratio of the crosslinking agent of the (meth)acrylic polymer, It is possible to obtain a surface protection film (adhesive layer) having better heat resistance.

As the crosslinking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine-based resin, an aziridine derivative, a metal chelate compound, or the like may be used, and the use of an isocyanate compound is particularly preferred. In addition, these compounds may be used alone or in combination of two or more.

Examples of the isocyanate compound include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI), dimer diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate. (IPDI), alicyclic isocyanates such as 1,3-bis(isocyanatomethyl)cyclohexane, 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate (XDI) Aromatic isocyanates such as allophanate bonds, burette bonds, isocyanurate bonds, uretdione bonds, urea bonds, carbodiimide bonds, uretonimine bonds, oxadiazinetrione bonds, etc. One polyisocyanate modified body is mentioned. For example, as a commercial product, product names: Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (above, manufactured by Mitsui Chemical Co., Ltd.), Summit T80, Summit L, and Death Module N3400 (above, Sumika Bayer Urethane), Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (above, manufactured by Tosoh Corporation), and the like. These isocyanate compounds may be used alone or in combination of two or more kinds, and it is also possible to use a bifunctional isocyanate compound and a trifunctional or higher isocyanate compound in combination. By using a crosslinking agent in combination, it is possible to achieve both adhesion and repulsion resistance (adhesive to a curved surface), and a surface protection film excellent in adhesion reliability can be obtained.

Examples of the epoxy compound include N,N,N',N'-tetraglycidyl-m-xylenediamine (trade name TETRAD-X, manufactured by Mitsubishi Gas Chemical Co., Ltd.) or 1,3-bis (N,N- And diglycidylaminomethyl)cyclohexane (trade name TETRAD-C, manufactured by Mitsubishi Gas Chemical Co., Ltd.).

Examples of the melamine-based resin include hexamethylol melamine and the like. Examples of the aziridine derivatives include HDU, TAZM, and TAZO (above, manufactured by Sogo Yakugo) as commercial products.

Examples of the metal chelating compound include aluminum, iron, tin, titanium, and nickel as metal components, and acetylene, methyl acetoacetate, and ethyl lactate as chelating components.

The content of the crosslinking agent used in the present invention is, for example, preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass relative to 100 parts by mass of the (meth)acrylic polymer. It is more preferable, and it is most preferably 1 to 6 parts by mass. When the content is less than 0.01 parts by mass, crosslinking by the crosslinking agent is insufficient, the cohesive force of the resulting pressure-sensitive adhesive layer is reduced, and sufficient heat resistance may not be obtained, and there is a tendency to cause residual adhesive. On the other hand, when the content exceeds 20 parts by mass, the cohesive force of the polymer is large, the fluidity decreases, the wettability to the adherend (e.g., polarizing film) becomes insufficient, and between the adherend and the pressure-sensitive adhesive layer (adhesive composition layer). It tends to cause swelling to occur. Moreover, these crosslinking agents may be used individually or may be used in mixture of 2 or more types.

The pressure-sensitive adhesive composition may further contain a crosslinking catalyst for more effectively proceeding any one of the crosslinking reactions described above. As such a crosslinking catalyst, for example, tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris(acetylacetonate) iron (iron(III)acetylacetonato), tris(hexane-2,4- Dionato) iron, tris (heptane-2,4-dionato) iron, tris (heptane-3,5-dionato) iron, tris (5-methylhexane-2,4-dionato) iron, tris (octane) -2,4-dionato) iron, tris(6-methylheptane-2,4-dionato) iron, tris(2,6-dimethylheptane-3,5-dionato) iron, tris(nonane-2, 4-dionato) iron, tris(nonane-4,6-dionato) iron, tris(2,2,6,6-tetramethylheptane-3,5-dionato) iron, tris(tridecane-6, 8-dionato) iron, tris(1-phenylbutane-1,3-dionato) iron, tris(hexafluoroacetylacetonate) iron, tris(ethyl acetoacetate) iron, tris(acetoacetic acid-n-propyl Iron, tris (isopropyl acetoacetate) iron, tris (acetoacetic acid-n-butyl) iron, tris (acetoacetic acid-sec-butyl) iron, tris (acetoacetic acid-tert-butyl) iron, tris (propionyl acetic acid) Methyl) iron, tris (ethyl propionyl acetate) iron, tris (propionyl acetate-n-propyl) iron, tris (propionyl acetate isopropyl) iron, tris (propionyl acetate-n-butyl) iron, tris (propy Onyl acetate-sec-butyl) iron, tris (propionyl acetate-tert-butyl) iron, tris (benzyl acetoacetate) iron, tris (dimethyl malonate) iron, tris (diethyl malonate) iron, trimethoxy iron, Iron-based catalysts such as triethoxy iron, triisopropoxy iron and ferric chloride can be used. These crosslinking catalysts may be used alone or in combination of two or more.

The content of the crosslinking catalyst is not particularly limited, but is preferably about 0.0001 to 1 part by mass, and more preferably 0.001 to 0.5 part by mass, for example, relative to 100 parts by mass of the (meth)acrylic polymer. When it is in the said range, when the pressure-sensitive adhesive layer is formed, the speed of the crosslinking reaction is fast, and the useful time of the pressure-sensitive adhesive composition becomes long, and it becomes a preferable form.

In addition, the pressure-sensitive adhesive composition may contain an alkylene oxide (AO) group-containing compound. Thereby, it becomes possible to improve the wettability to the adherend, it is possible to improve the adhesion to the adherend, and it becomes easy to suppress the mixing of bubbles or the like generated at the time of joining.

As specific examples of the alkylene oxide (AO) group-containing compound, for example, polyoxyalkylene alkylamine, polyoxyalkylene diamine, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene Alkyl phenyl ether, polyoxyalkylene alkyl ether, polyoxyalkylene allyl ether, polyoxyalkylene alkyl allyl ether, polyoxyalkylene alkylphenyl allyl ether, polyalkylene glycol dialkyl ester, polyalkylene glycol diaryl ester Nonionic surfactants such as; Polyoxyalkylene alkyl ether sulfate ester salt, polyoxyalkylene allyl ether sulfate ester salt, polyoxyalkylene alkyl ether phosphoric acid ester salt, polyoxyalkylene alkylphenyl ether sulfate ester salt, polyoxyalkylene alkylallylphenyl ether sulfate Anionic surfactants such as ester salts and polyoxyalkylene alkylphenyl ether phosphate ester salts; In addition, cationic surfactants or cationic surfactants having polyoxyalkylene chains (polyalkylene oxide chains), polyether compounds having polyoxyalkylene chains (and derivatives thereof), and polyoxyalkylene chains Ester compounds (and derivatives thereof), acrylic compounds having a polyoxyalkylene chain (and derivatives thereof), and the like. Moreover, you may mix|blend polyoxyalkylene chain containing monomer as an acryl-type polymer as a polyoxyalkylene chain containing compound. These polyoxyalkylene chain-containing compounds may be used alone or in combination of two or more.

As specific examples of the ether compound having the polyoxyalkylene chain, a block copolymer of polypropylene glycol (PPG)-polyethylene glycol (PEG), a block copolymer of PPG-PEG-PPG, a block copolymer of PEG-PPG-PEG, etc. Can be heard. As a derivative of the ether compound having a polyoxyalkylene chain, the terminal-etherified oxypropylene group-containing compound (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.), the terminal-acetylated oxypropylene group-containing compound (terminal And acetylated PPG).

Moreover, the ester compound which has an oxyalkylene group is mentioned as a specific example of the said ester compound which has a polyoxyalkylene chain. As said oxyalkylene group, 1-50 are preferable, 2-30 are more preferable, and 2-20 are more preferable from the viewpoint which an ionic compound coordinates, the added mole number of an oxyalkylene unit. Specific examples include diethylene glycol dibenzoate, triethylene glycol dibenzoate, tetraethylene glycol dibenzoate, polyethylene glycol dibenzoate, polypropylene glycol dibenzoate, polyethylene glycol-2-ethylhexonate benzoate, and the like. Can be.

Moreover, as a specific example of the said acrylic compound which has a polyoxyalkylene chain, the (meth)acrylate polymer which has an oxyalkylene group is mentioned. As said oxyalkylene group, 1-50 are preferable, 2-30 are more preferable, and 2-20 are more preferable from the viewpoint which an ionic compound coordinates, the added mole number of an oxyalkylene unit. Moreover, the terminal of the said oxyalkylene chain may be substituted by the state of a hydroxyl group, an alkyl group, a phenyl group, or the like.

The (meth)acrylate polymer having the oxyalkylene group is preferably a polymer containing (meth)acrylate alkylene oxide as a monomer unit (component), and as a specific example of the (meth)acrylate alkylene oxide, ethylene glycol Examples of the group-containing (meth)acrylate include methoxy-polyethylene glycol (meth)acrylate types such as methoxy-diethylene glycol (meth)acrylate and methoxy-triethylene glycol (meth)acrylate, e Ethoxy-polyethylene glycol (meth)acrylate type such as ethoxy-diethylene glycol (meth)acrylate, ethoxy-triethylene glycol (meth)acrylate, butoxy-diethylene glycol (meth)acrylate, butoxy -Bethoxy-polyethylene glycol (meth)acrylate type such as triethylene glycol (meth)acrylate, phenoxy-diethylene glycol (meth)acrylate, phenoxy-triethylene glycol (meth)acrylate and other phenoxy -Methoxy such as polyethylene glycol (meth)acrylate type, 2-ethylhexyl-polyethylene glycol (meth)acrylate, nonylphenol-polyethylene glycol (meth)acrylate type, methoxy-dipropylene glycol (meth)acrylate -Polypropylene glycol (meth)acrylate type etc. are mentioned.

Further, as the monomer unit (component), other monomer units (components) other than the (meth)acrylate alkylene oxide can also be used. Examples of other monomer components include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, and isobutyl (Meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, iso Nonyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth) Acrylates and/or methacrylates having alkyl groups having 1 to 14 carbon atoms such as acrylates.

In addition, as other monomer units (components) other than the (meth)acrylate alkylene oxide, carboxyl group-containing (meth)acrylate, phosphoric acid group-containing (meth)acrylate, cyano group-containing (meth)acrylate, vinyl esters, aromatics Vinyl compound, acid anhydride group-containing (meth)acrylate, hydroxyl group-containing (meth)acrylate, amide group-containing (meth)acrylate, amino group-containing (meth)acrylate, epoxy group-containing (meth)acrylate, N- It is also possible to appropriately use acryloyl morpholine, vinyl ethers, and the like.

The average molecular weight (Mn) of the alkylene oxide (AO) group-containing compound is preferably 50000 or less, preferably 200 to 30000, more preferably 200 to 10000, and usually 200 to 5000 Is used. When Mn is excessively larger than 50000, compatibility with an acrylic polymer decreases, and the pressure-sensitive adhesive layer tends to whiten. If Mn is too small than 200, contamination with the polyoxyalkylene compound may easily occur. In addition, Mn here means the value of polystyrene conversion obtained by gel permeation chromatography (GPC).

The content of the alkylene oxide (AO) group-containing compound is not particularly limited, but may be, for example, about 0.005 to 20 parts by mass, preferably 0.01 to 15 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer. Part, more preferably 0.05 to 10 parts by mass, most preferably 0.1 to 4 parts by mass. If the blending amount is too small, the wettability effect to the adherend is reduced, and if the amount is too large, contamination by the polyoxyalkylene compound is likely to occur, and optical properties of the optical member may be impaired.

Further, the pressure-sensitive adhesive composition may contain other known additives, for example, powders such as lubricants, colorants, pigments, plasticizers, tackifiers, low molecular weight polymers, surface lubricants, leveling agents, antioxidants, and corrosion inhibitors , Light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, antistatic agents, crosslinking retarders, inorganic or organic fillers, metal powders, particulates, thin materials and the like can be appropriately added according to the application.

<Adhesive layer and surface protection film>

The surface protection film of the present invention is formed by forming the pressure-sensitive adhesive layer on at least one side of the base film. At that time, crosslinking of the pressure-sensitive adhesive composition is generally performed after application of the pressure-sensitive adhesive composition, but the pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition after crosslinking is silicone-based. , After forming on a separator having a release agent layer of a fluorine-based, long-chain alkyl-based or fatty acid amide-based, it is also possible to transfer to a base film or the like.

The method of forming the pressure-sensitive adhesive layer on the base film is not particularly concerned, but for example, it is prepared by applying the pressure-sensitive adhesive composition (solution) to the base film, drying and removing the polymerization solvent, etc., and forming the pressure-sensitive adhesive layer on the base film. do. Thereafter, curing may be performed for the purpose of adjusting the component migration of the pressure-sensitive adhesive layer or adjusting the crosslinking reaction. Moreover, when apply|coating an adhesive composition on a base film, and manufacturing a surface protection film, you may newly add 1 or more types of solvent other than a polymerization solvent in the said adhesive composition so that it can apply uniformly on a base film.

In addition, as a method of forming the pressure-sensitive adhesive layer when producing the surface protection film of the present invention, a known method used for the production of pressure-sensitive adhesive tapes is used. Specifically, a roll coat, a gravure coat, a reverse coat, a roll brush, a spray coat, the air knife coating method, the extrusion coat method by a die coater etc. are mentioned, for example.

In the surface protection film of the present invention, the thickness of the pressure-sensitive adhesive layer is less than 2 μm, preferably 0.1 μm or more and less than 2 μm, more preferably 0.2 to 1.5 μm, still more preferably 0.4 to 1.2 μm, particularly It is preferably 0.5 to 1 µm. When the thickness of the pressure-sensitive adhesive layer is within the above range, the gauge peeling force is lowered, and after attaching to a thin optical member or a display panel, a surface protection film is easily removed, which is preferable because it can be easily peeled off.

The pressure-sensitive adhesive layer preferably has a shear storage modulus (G′) at 23° C. of 1.0×10 ⁴ to 1.0×10 ⁷ ㎩, more preferably 1.0×10 ⁵ to 5.0×10 ⁶ ,, and even more preferably. Is 3.0×10 ⁵ to 5.0×10 ⁶ MPa. By adjusting within the above-mentioned range, while the gauge peeling force is suppressed to be low, adhesion to the surface of the adherend can be ensured and bonding can be easily performed, resulting in a preferable form.

In addition, the peeling force of the 90° peel gauge at 50%RH at 23°C to the triacetylcellulose film (polarizing film) of the surface protective film (the pressure-sensitive adhesive layer) is preferably 1 N/50 mm or less, and more preferably Is 0.05 to 1 N/50 mm, more preferably 0.1 to 0.95 N/50 mm, and particularly preferably 0.2 to 0.9 N/50 mm. When the gauge peeling force exceeds 1 N/50 mm, peeling resistance is applied when peeling the surface protective film from the polarizing film with the pick-up tape, and it is not preferable because peeling becomes difficult.

The surface protection film of the present invention preferably has a total thickness of 20 to 400 μm, more preferably 30 to 200 μm, even more preferably 40 to 150 μm, and particularly preferably 50 to 100 μm. If it is within the above range, the adhesive properties (removability, adhesive properties, etc.), workability, and appearance properties are excellent, resulting in a preferred form. In addition, the said total thickness means the sum of the thickness which includes all layers, when a base film, an adhesive layer, or another layer exists.

<Separator>

In the surface protection film of the present invention, if necessary, it is possible to bond the separator to the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer.

As a material constituting the separator, there is a paper or plastic film, but a plastic film is suitably used because of its excellent surface smoothness. The film is not particularly limited as long as it is a film that can protect the pressure-sensitive adhesive layer. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride air And a coalescence film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

The thickness of the separator is usually 5 to 200 μm, preferably about 10 to 100 μm. When it is in the above-mentioned range, it is preferable because it is excellent in bonding work to the pressure-sensitive adhesive layer and peeling work from the pressure-sensitive adhesive layer. If necessary, the separator may be subjected to release and antifouling treatment with a silicone-based, fluorine-based, long-chain alkyl- or fatty acid amide-based release agent, silica powder, or antistatic treatment such as coating, mixing, and vapor deposition.

<absence of optics>

It is preferable that the optical member of the present invention is protected by the surface protection film. The surface protection film can be used for surface protection purposes such as processing, transportation, and shipping, and is useful for protecting the surface of the optical member (polarizing film, etc.). In particular, it becomes very useful for a thin optical member (such as a polarizing film) or a display panel because it can be easily peeled off at a stage where a surface protection film is unnecessary.

The optical member of the present invention is a polarizing film containing a polarizer, and the thickness of the polarizer is preferably 8 μm or less. When the thickness of the polarizer is as thin as 8 µm or less, it is a useful and preferable form for an optical member (polarizing film) that requires thinning in recent years.

<Polarizing film>

As said polarizing film, the thing of the structure which laminated|stacked the transparent protective film on at least one surface of a polarizer and a polarizer, and laminated the 1st adhesive layer on at least one surface of the said polarizing film can be used.

<Polarizer>

The polarizer used is a polyvinyl alcohol-based resin. As a polarizer, for example, a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and a hydrophilic polymer film such as an ethylene-vinyl acetate copolymer-based partially saponified film are adsorbed and uniaxially adsorbed by a dichroic substance such as iodine or a dichroic dye. And a polyene-based alignment film such as a stretched product, a dehydration product of polyvinyl alcohol, or a dehydrochloric acid product of polyvinyl chloride. Among these, a polarizer made of a dichroic material such as polyvinyl alcohol-based film and iodine is suitable.

The polarizer which is uniaxially stretched by dyeing the polyvinyl alcohol-based film with iodine can be produced by, for example, dyeing polyvinyl alcohol by immersion in an aqueous solution of iodine, and stretching by 3 to 7 times the original length. If necessary, boric acid, zinc sulfate, zinc chloride, or the like may be included, or it may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed before dyeing. By washing the polyvinyl alcohol-based film with water, it is possible to clean the surface of the polyvinyl alcohol-based film or an antiblocking agent, and also has the effect of preventing unevenness such as staining by dyeing the polyvinyl alcohol-based film. Stretching may be performed after dyeing with iodine, stretching may be performed while dyeing, or dyeing with iodine may be performed after stretching. Stretching is also possible in aqueous solutions such as boric acid and potassium iodide and water baths.

The thickness of the polarizer is preferably 8 µm or less from the viewpoint of thinning, more preferably 7 µm or less, and even more preferably 6 µm or less. On the other hand, the thickness of the polarizer is preferably 2 µm or more, and further 3 µm or more. Such a thin polarizer has excellent thickness resistance, excellent visibility, and little dimensional change, and thus has excellent durability against thermal shock. As a thin polarizer, representatively, Japanese Patent No. 471486, Japanese Patent No. 447541, Japanese Patent No. 4815544, Japanese Patent No. 5048120, International Publication No. 2014/077599, International Publication No. 2014/ And thin polarizers described in the 077636 pamphlet or the like, or thin polarizers obtained from the production methods described in these.

The polarizer has an optical characteristic expressed by a single transmittance T and a polarization degree P, and the following equations P>-(100.929T-42.4-1)×100 (where T<42.3) or P≥99.9 (where T≥ It is preferably configured to satisfy the conditions of 42.3). The polarizer configured to satisfy the above conditions has the required performance as a display for a liquid crystal TV using a large display element. Specifically, the contrast ratio is 1000:1 or more and the maximum luminance is 500 cd/m 2 or more. As another use, it is bonded to the viewer side of an organic EL cell, for example.

Among the manufacturing methods including the step of stretching in the form of a laminate and the step of dyeing, the thin polarizer can be stretched at a high magnification to improve polarization performance, and therefore, Japanese Patent No. 4714486 specification, Japanese Patent No. 4751481 It is preferably obtained by a manufacturing method comprising a process of stretching in an aqueous solution of boric acid as described in the specifications of the specification and the patent 4815544, particularly before stretching in any of the aqueous solutions of boric acid described in the specification of Japanese Patent No. It is preferable to obtain by the manufacturing method including the process of air-stretching. These thin polarizers can be obtained by a manufacturing method including a process of stretching a polyvinyl alcohol-based resin (hereinafter, also referred to as a PVA-based resin) layer and a resin base film for stretching in the form of a laminate and dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it is supported on the resin base film for stretching, so that it can be stretched without problems such as breakage due to stretching.

(Transparent protective film)

The material constituting the transparent protective film is not particularly limited, but is preferably excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and the like. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene or acrylonitrile styrene copolymer And styrene-based polymers such as (AS resin), polycarbonate-based polymers, and the like. In addition, polyolefin-based polymers such as polyethylene, polypropylene, cyclo- or norbornene structures, polyolefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamides, imide-based polymers, and alcohols Phone-based polymer, polyether sulfone-based polymer, polyether ether ketone-based polymer, polyphenylene sulfide-based polymer, vinyl alcohol-based polymer, vinylidene chloride-based polymer, vinyl butyral-based polymer, arylate-based polymer, polyoxymethylene-based polymer, Epoxy-based polymers or blends of the polymers are also examples of the polymer forming the transparent protective film. These transparent protective films are usually bonded to a polarizer by an adhesive layer. Moreover, one or more types of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, coloring inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, coloring agents and the like.

The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100 mass%, more preferably 50 to 99 mass%, still more preferably 60 to 98 mass%, particularly preferably 70 to 97 mass% to be. When the content of the thermoplastic resin in the transparent protective film is 50% by mass or less, there is a concern that the high transparency or the like inherent in the thermoplastic resin cannot be sufficiently expressed.

The thickness of the transparent protective film can be appropriately determined, but in general, it is preferably 5 to 50 µm, more preferably 5 to 45 µm, from the viewpoint of workability such as strength and handling, and thin layer.

A functional layer such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer or an anti-glare layer may be formed on a surface of the transparent protective film that does not adhere the polarizer. In addition, functional layers such as the hard coat layer, the anti-reflection layer, the anti-sticking layer, the diffusion layer, and the anti-glare layer can be provided on the transparent protective film itself, or can be separately installed from the transparent protective film. .

The transparent protective film and the polarizer are laminated through intervening layers such as an adhesive layer, an adhesive layer, and a primer layer (primer layer). At this time, it is preferable to stack both without an air gap by the intervening layer.

The adhesive layer is formed by an adhesive. The type of adhesive is not particularly limited, and various types of adhesives can be used. The adhesive layer is not particularly limited as long as it is optically transparent, and various types of adhesives such as water-based, solvent-based, hot-melt-based, and active-energy-ray-curable types are used as the adhesive, but water-based adhesives or active-energy-ray-curable adhesives are suitable.

Examples of the water-based adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based, and water-based polyesters. The aqueous adhesive is usually used as an adhesive composed of an aqueous solution, and usually contains 0.5 to 60% by mass of solid content.

The active energy ray-curable adhesive is an adhesive that is cured by active energy rays such as electron beams and ultraviolet rays (radical curing type, cationic curing type), and may be used in the form of electron beam curing type or ultraviolet curing type. As the active energy ray-curable adhesive, for example, a photo-radical curable adhesive can be used. When a photo-radical-curable active energy ray-curable adhesive is used as an ultraviolet-curable adhesive, the adhesive contains a radically polymerizable compound and a photopolymerization initiator.

The method of applying the adhesive is appropriately selected depending on the viscosity of the adhesive or the desired thickness. Examples of the coating method include reverse coater, gravure coater (direct, reverse or offset), bar reverse coater, roll coater, die coater, bar coater, and rod coater. In addition, a method such as a dipping method can be appropriately used for coating.

Further, when applying the adhesive, when using a water-based adhesive or the like, it is preferable to perform such that the thickness of the finally formed adhesive layer is 30 to 300 nm, more preferably 60 to 150 nm. On the other hand, in the case of using an active energy ray-curable adhesive, it is preferable that the thickness of the adhesive layer is 0.2 to 20 μm.

In addition, in the lamination of the polarizer and the transparent protective film, an easily bonding layer can be formed between the transparent protective film and the adhesive layer. The easily bonding layer can be formed of various resins having, for example, a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based, polyamide skeleton, polyimide skeleton, polyvinyl alcohol skeleton, and the like. have. These polymer resins can be used alone or in combination of two or more. In addition, other additives may be added to the formation of the easily bonding layer. Specifically, further stabilizers such as tackifiers, ultraviolet absorbers, antioxidants, and heat-resistant stabilizers may be used.

The pressure-sensitive adhesive layer is formed of an adhesive (adhesive composition). As the pressure-sensitive adhesive, various pressure-sensitive adhesives can be used, and examples thereof include rubber pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, urethane pressure-sensitive adhesives, vinyl alkyl ether pressure-sensitive adhesives, polyvinylpyrrolidone pressure-sensitive adhesives, polyacrylamide pressure-sensitive adhesives, and cellulose pressure-sensitive adhesives. have. An adhesive base polymer is selected according to the type of the adhesive. Among the pressure-sensitive adhesives, an acrylic pressure-sensitive adhesive is preferably used from the viewpoint of excellent optical transparency, moderate wettability, cohesiveness, and adhesive properties, and excellent weatherability and heat resistance.

The base layer (primer layer) is formed to improve the adhesion between the polarizer and the transparent protective film. The material constituting the primer layer is not particularly limited as long as it is a material that exhibits some strong adhesion to both the base film and the polyvinyl alcohol-based resin layer. For example, a thermoplastic resin having excellent transparency, thermal stability, stretchability, and the like is used. Examples of the thermoplastic resin include acrylic resins, polyolefin resins, polyester resins, polyvinyl alcohol resins, and mixtures thereof.

<First adhesive layer>

A structure in which a first pressure-sensitive adhesive layer is laminated on at least one surface of the polarizing film can be used, and other optical members (for example, on a surface opposite to the surface in contact with the polarizing film of the first pressure-sensitive adhesive layer) Phase difference films, liquid crystal display devices, and the like). In addition, the first pressure-sensitive adhesive layer may be directly laminated on the underlying layer laminated on the polarizer. A suitable pressure-sensitive adhesive can be used to form the first pressure-sensitive adhesive layer, and there is no particular limitation on the type. Examples of the adhesive include rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Among these pressure sensitive adhesives, those having excellent optical transparency, exhibiting moderate wettability, cohesiveness and adhesive pressure-sensitive adhesive properties, and excellent weather resistance and heat resistance are preferably used. As exhibiting such characteristics, an acrylic adhesive is preferably used.

As a method of forming the first pressure-sensitive adhesive layer, for example, after applying the pressure-sensitive adhesive to a separator subjected to a peeling treatment, drying and removing the polymerization solvent, etc. to form the pressure-sensitive adhesive layer, the method is transferred to a polarizing film or the polarizing film It is produced by applying a pressure-sensitive adhesive, drying and removing a polymerization solvent, and the like to form a pressure-sensitive adhesive layer on a polarizer. In addition, in the application of the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be added as appropriate. As the separator subjected to the peeling treatment, a silicon separator is preferably used.

In the step of applying and drying the pressure-sensitive adhesive of the present invention on such a separator to form the pressure-sensitive adhesive layer, as a method of drying the pressure-sensitive adhesive, an appropriate method may be appropriately employed depending on the purpose. Preferably, a method of overheating and drying the coating film is used. The heating and drying temperature is preferably 40 to 200°C, more preferably 50 to 180°C, and particularly preferably 70 to 170°C. By setting the heating temperature within the above range, an adhesive having excellent adhesive properties can be obtained.

As the method for forming the first pressure-sensitive adhesive layer, various methods are used. Specifically, for example, by roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. And methods such as an extrusion coat method.

The thickness of the first pressure-sensitive adhesive layer is preferably 2 to 50 μm, more preferably 2 to 40 μm, and even more preferably 5 to 35 μm.

The separator can protect the adhesive surface of the first adhesive layer until it is provided for practical use. As the constituent material of the separator, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabrics, nets, foam sheets, metal foils, and laminates thereof Although a suitable thin body is mentioned, a plastic film is suitably used from the viewpoint of excellent surface smoothness. The plastic film is not particularly limited as long as it is a film that can protect the pressure-sensitive adhesive layer. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, chloride And vinyl copolymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, and ethylene-vinyl acetate copolymer films.

If necessary, the separator may be subjected to release and antifouling treatment with silicone-based, fluorine-based, long-chain alkyl- or fatty acid amide-based release agents, silica powder, or antistatic treatments such as coating, mixing, and vapor deposition. In particular, peeling treatment from the first pressure-sensitive adhesive layer can be further enhanced by appropriately performing a peeling treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release film.

The thickness of the separator is usually 5 to 50 μm, and more preferably 20 to 40 μm.

[Example]

Hereinafter, some examples related to the present invention will be described, but the present invention is not intended to be limited to those shown in these specific examples. In addition, "part" and "%" in the following description are a basis of mass, unless otherwise specified. Moreover, the compounding quantity (addition amount) in a table was shown.

In addition, each characteristic in the following description was measured or evaluated as follows.

<Weight average molecular weight (Mw)>

The weight average molecular weight (Mw) was measured using the GPC apparatus (HLC-8220GPC) manufactured by Tosoh Corporation. Measurement conditions are as follows.

Sample concentration: 0.2% by mass (THF solution)

Sample injection volume: 10 μl

Eluent: THF

Flow rate: 0.6ml/min

Measurement temperature: 40℃

column:

Sample column; TSKguardcolumn Super㎐-H (1 pc.) + TSKgel Super㎐M-H (2 pcs.)

Reference column; TSKgel SuperH-RC (1 pc.)

Detector: Differential Refractometer (RI)

In addition, the weight average molecular weight was calculated|required by polystyrene conversion value.

<Glass transition temperature (Tg)>

The glass transition temperature Tg (°C) of the polymer was obtained by using the following literature value as the glass transition temperature Tgn (°C) of the homopolymer by each monomer and using the following formula.

Formula: 1/(Tg+273)=Σ[Wn/(Tgn+273)]

[Wherein, Tg(℃) is the glass transition temperature of the copolymer, Wn(-) is the mass fraction of each monomer, Tgn(℃) is the glass transition temperature of the homopolymer by each monomer, and n is the type of each monomer. Shows.]

Literature value:

2-ethylhexyl acrylate (2EHA): -70°C

Butyl acrylate (BA): -55℃

2-hydroxyethyl acrylate (HEA): -15°C

Acrylic acid (AA): 106℃

As reference values, reference was made to "synthesis and design of acrylic resins and development of creditworthiness" (published by the Central Management Development Center Press), "Polymer Handbook" (John Wiley & Sons), and monomer manufacturer catalog values.

Note that the glass transition temperature (Tg) (° C.) of the (meth)acrylic polymer obtained by the monomer with unclear literature values can be determined by dynamic viscoelasticity measurement in the following procedure.

First, a sheet of a (meth)acrylic polymer having a thickness of 20 µm was laminated to a thickness of about 2 mm, and this was punched to φ 7.9 mm, and a cylindrical pellet was prepared to prepare a sample for measuring the glass transition temperature (Tg). .

Using the measurement sample, the measurement sample was fixed to a jig of a φ7.9 mm parallel plate, and the temperature dependence of the loss elastic modulus G" was measured by a dynamic viscoelasticity measuring device (ARES, manufactured by Rheometrics) and obtained. The temperature at which the G" curve is maximized is called the glass transition temperature (Tg) (°C). Measurement conditions are as follows.

Measurement: shear mode

Temperature range: -70℃ to 150℃

Heating temperature range: 5℃/min

Frequency: 1 kHz

<Storage modulus (G')>

A sheet of an adhesive layer having a thickness of 20 µm was stacked to a thickness of about 2 mm, punched to φ 7.9 mm, and a cylindrical pellet was prepared to prepare a sample for measuring the storage modulus.

The sample for measurement was fixed to a jig of a φ7.9 mm parallel plate, and the storage elastic modulus (㎩) at a temperature of 23° C. and a frequency of 1 Hz was measured by a dynamic viscoelasticity measuring device (ARES, manufactured by Rheometrics). In addition, the measurement of storage elastic modulus was performed about the thing which used the acrylic adhesive.

<Thickness measurement>

The cross section of the surface protection film was observed using the transmission electron microscope (H-7650 manufactured by Hitachi Seisakusho), and the thickness of the pressure-sensitive adhesive layer or the like was measured.

<Instrument peeling force (pickup force)>

As shown in Fig. 2, the surface protection film 1 according to each example is cut to a size of 50 mm in width and 100 mm in length to make the adhesive surface 20A of this surface protection film 1 the following piece protective polarizing film On the (50), pressure was applied at a pressure of 0.25 MPa and a speed of 0.3 m/min. A single-sided adhesive tape (manufactured by Nichi Corporation, brand name "Cellophane tape (registered trademark)", width 24 mm) 60 was cut to a length of 50 mm. The pressure-sensitive adhesive surface of this pressure-sensitive adhesive tape was pressed with a hand roller on the center of the back surface of a width of 50 mm of the surface protection film 1 so that the end portion was 30 mm. This was left for 10 seconds under conditions of 23°C and 50%RH. Thereafter, when the single-sided adhesive tape 60 was peeled off with an autograph at a rate of 0.3 m/min in the 90° direction, the maximum stress applied at the beginning of peeling was taken as the gauge peeling force (N/50 mm).

<Preparation of polarizing film>

(Production of polarizer)

An amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 µm) having an absorption rate of 0.75% and a Tg of 75°C was subjected to corona treatment on one surface of the substrate, and polyvinyl alcohol (polymerization degree) was applied to the corona treated surface. 4200, saponification degree 99.2 mol%) and acetyl acetyl modified PVA (polymerization degree 1200, acetyl acetylation degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon Kose Chemical Co., Ltd., trade name ``Kose Pymer Z200'') 9:1 An aqueous solution containing at a ratio of was applied and dried at 25°C, and a PVA-based resin layer having a thickness of 11 µm was formed to produce a laminate.

The obtained laminate was uniaxially stretched freely 2.0 times in the longitudinal direction (longitudinal direction) between rolls of different circumferential speeds in an oven at 120°C (air assisted stretching treatment).

Subsequently, the layered product was immersed in an insolubilization bath at a liquid temperature of 30°C (an aqueous solution of boric acid obtained by mixing 4 parts by mass of boric acid with respect to 100 parts by mass of water) for 30 seconds (insolubilization treatment).

Subsequently, it was immersed in a dyeing bath at a liquid temperature of 30°C while adjusting the iodine concentration and immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 part by weight of iodine was blended with respect to 100 parts by weight of water, and 1.0 part by weight of potassium iodide was blended, followed by immersion in an aqueous solution of iodine for 60 seconds (staining treatment).

Subsequently, it was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 30°C (an aqueous solution of boric acid obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) (crosslinking treatment).

Thereafter, the layered product was immersed in an aqueous solution of boric acid at a liquid temperature of 70°C (an aqueous solution obtained by mixing 4 parts by weight of boric acid with respect to 100 parts by weight of water and 5 parts by weight of potassium iodide), and between rolls having different circumferential speeds. Uniaxial stretching was performed in the longitudinal direction (longitudinal direction) so that the total draw ratio was 5.5 times (underwater stretching treatment).

Thereafter, the layered product was immersed in a washing bath at a liquid temperature of 30°C (an aqueous solution obtained by mixing 4 parts by mass of potassium iodide with respect to 100 parts by mass of water) (washing treatment). Thus, an optical film laminate comprising a polarizer having a thickness of 5 μm was obtained.

(Formation of adhesive layer)

In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirring device, 100 parts of butyl acrylate, 3 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate and 0.3 part of 2,2'-azobisisobutyronitrile acetic acid The solution was prepared by adding with ethyl. Subsequently, the solution was stirred while blowing nitrogen gas, and reacted at 55°C for 8 hours to obtain a solution containing an acrylic polymer having a weight average molecular weight of 2.2 million. Further, ethyl acetate was added to the solution containing the acrylic polymer to obtain an acrylic polymer solution in which the solid content concentration was adjusted to 30%.

With respect to 100 parts of the solid content of the acrylic polymer solution, as a crosslinking agent, a crosslinking agent containing a compound having an isocyanate group of 0.5 parts as a main component (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L"), and a silane coupling agent, 0.075 parts γ-glycidoxypropyl trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KMB-403") was blended in this order to prepare an adhesive solution. The pressure-sensitive adhesive solution was applied to the surface of a release sheet (separator) made of a release-treated polyethylene terephthalate film (38 µm thick) so that the thickness after drying was 25 µm, dried, and the pressure-sensitive adhesive layer was formed.

(Production of a piece protective polarizing film)

A 40 µm-thick triacetyl cellulose (TAC) film (trade name “TAC Film KC4UY” manufactured by Konica Minolta Opt) was bonded to the polarizer side of the optical film laminate through a vinyl alcohol adhesive. Subsequently, the amorphous PET substrate was peeled off, and the pressure-sensitive adhesive layer was bonded to the peeling surface to prepare a piece protective polarizing film.

<Preparation of acrylic polymer (1)>

95 parts by mass of 2-ethylhexyl acrylate (2EHA), 5 parts by mass of 2-hydroxyethyl acrylate (HEA) in a 4-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler, 2 as a polymerization initiator, 0.2 mass parts of 2'-azobisisobutyronitrile and 150 mass parts of ethyl acetate were added, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was maintained at around 65°C to perform a polymerization reaction for 6 hours, and an acrylic polymer (1) A solution (40% by mass) was prepared. The acrylic polymer (1) had a weight average molecular weight (Mw) of 550,000, and a glass transition temperature (Tg) of -68°C.

<Production of acrylic polymer (2)>

95 parts by mass of butyl acrylate (BA), 5 parts by mass of acrylic acid (AA), 2,2'-azobisisobutyronitrile as polymerization initiator in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler 0.2 parts by mass and 234 parts by mass of ethyl acetate were added, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was maintained at about 63°C and polymerization reaction was carried out for 7 hours to obtain an acrylic polymer (2) solution (30% by mass). Was prepared. The acrylic polymer (2) had a weight average molecular weight (Mw) of 600,000 and a glass transition temperature (Tg) of -50°C.

(Preparation of acrylic adhesive 1 solution)

The acrylic polymer (1) solution (40 mass%) was diluted with ethyl acetate to 20 mass%, and trimethylolpropane/tolyl, a trifunctional isocyanate compound, was used as a crosslinking agent in 500 mass parts (100 mass parts of solid content) of this solution. Rendiisocyanate trimer adduct (manufactured by Tosoh Corporation, Coronate L:C/L) 2.7 parts by mass (solids 2 parts by mass), dibutyltin dilaurate (1% by mass ethyl acetate solution) 3 parts by mass (solids 0.03) Parts by mass) and mixing and stirring to prepare an acrylic pressure-sensitive adhesive 1 solution.

(Preparation of acrylic adhesive 2 solution)

The acrylic polymer (1) solution (40% by mass) was diluted with ethyl acetate to 20% by mass, and 500 parts by weight of this solution (100 parts by mass of solid content) was used as a crosslinking agent to prepare isocyanate of hexamethylene diisocyanate, a trifunctional isocyanate compound. Anurate body (manufactured by Tosoh Corporation, Coronate HX:C/HX) 4 parts by mass (solids 4 parts by mass), 3 parts by mass of dibutyltin dilaurate (1% by mass of ethyl acetate solution) as a crosslinking catalyst (0.03 parts by mass of solids) Was added and mixed and stirred to prepare an acrylic pressure-sensitive adhesive 2 solution.

(Preparation of acrylic adhesive 3 solution)

The acrylic polymer (2) solution (30 mass%) was diluted with ethyl acetate to 20 mass%, and as a crosslinking agent in 500 mass parts (100 mass parts of solid content) of this solution, an epoxy compound (manufactured by Mitsubishi Gas Chemical Co., Ltd., TETRAD-C) :T/C) 5 parts by mass (5 parts by mass of solid content) was added and stirring was performed to prepare an acrylic adhesive 3 solution.

<Example 1>

(Preparation of surface protection film)

The acrylic pressure-sensitive adhesive 1 solution was applied to one side of a 38 µm thick polyester film (Toyobo, E5000), and heated at 130° C. for 2 minutes to form a 1 µm thick adhesive layer. Subsequently, a silicone-treated surface of a polyethylene terephthalate film (25 µm thick) subjected to silicone treatment on one surface was bonded to the surface of the pressure-sensitive adhesive layer to prepare a surface protection film.

<Example 2>

(Preparation of surface protection film)

A surface protective film was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution 2 was used.

<Example 3>

(Preparation of surface protection film)

Using the acrylic pressure-sensitive adhesive solution 2, except for forming a pressure-sensitive adhesive layer having a thickness of 1.9㎛ on one side of a 50㎛ thick polyester film (Toyobo, E5000) as the base film, in the same manner as in Example 2 A surface protective film was produced.

<Example 4>

(Preparation of surface protection film)

The acrylic pressure-sensitive adhesive solution 3 was applied to one side of a 38 µm-thick polyester film (Toyobo, E5000), and heated at 130° C. for 2 minutes to form a pressure-sensitive adhesive layer with a thickness of 0.5 µm. Subsequently, a silicone-treated surface of a polyethylene terephthalate film (25 µm thick) subjected to silicon treatment on one surface was bonded to the surface of the pressure-sensitive adhesive layer to prepare a surface protection film.

<Examples 5 to 9>

In the same manner as in Example 4, using the acrylic pressure-sensitive adhesive 3 solution, the pressure-sensitive adhesive layers shown in Table 3 (0.5 μm, 1 μm, 1.9 μm), each thickness (25 μm, 38 μm, 50 μm, 75 The surface protection film was produced by coating-forming on one side of the polyester film (Toyo Corporation, E5100: 38 µm, 50 µm, 75 µm base film, E5101: 25 µm base film).

<Example 10>

(Preparation of urethane-based adhesive 4 solution)

As a polyol, 85 parts by mass of preminol S3011 (manufactured by Asahi Glass Co., Ltd., Mn=10000), which is a polyol having three hydroxyl groups, Sannics GP3000 (manufactured by Sanyo Kasei, Mn=3000), which is a polyol having three hydroxyl groups ) 13 parts by mass, 2 parts by mass of Sannics GP1000 (manufactured by Sanyo Kasei, Mn = 1000), a polyol having 3 hydroxyl groups, 18 parts by mass of isocyanate compound (coronate HX:C/HX, manufactured by Tosoh Corporation) as a crosslinking agent As a catalyst, 0.04 parts by mass of iron (III) acetylacetonato (manufactured by Tokyo Chemical Industry Co., Ltd.) and 210 parts by mass of ethyl acetate as a diluting solvent were blended to obtain a urethane-based adhesive 4 solution.

(Preparation of surface protection film)

A surface protection film was produced under the same method and conditions as in Example 1 except that the urethane-based adhesive 4 solution was used.

<Example 11>

(Preparation of a silicone-based adhesive 5 solution)

As a silicone adhesive, ``X-40-3229'' (60% by mass solid content, manufactured by Shin-Etsu Chemical Co., Ltd.) is 100 parts by mass as a solid content, ``CAT-PL-50T'' (made by Shin-Etsu Chemical Co., Ltd.) as a platinum catalyst. 0.5 parts by mass and 100 parts by mass of toluene as a solvent were blended to obtain a silicone-based adhesive 5 solution.

(Preparation of surface protection film)

A surface protective film was produced under the same method and conditions as in Example 1, except that the silicone-based pressure-sensitive adhesive 5 solution was used.

<Example 12>

(Preparation of acrylic adhesive 6 solution)

The acrylic polymer (1) solution (40 mass%) was diluted with ethyl acetate to 20 mass%, and to this solution 500 mass parts (100 mass parts of solid content), 25R-1 (as an alkylene oxide (AO) group-containing compound) Polyoxyethylene-polyoxypropylene block polymer manufactured by ADEKA, trade name "Adeka Pluronic 25R-1") 0.5 parts by mass (0.5 parts by mass of solid content), isocylic acid of hexamethylene diisocyanate, a trifunctional isocyanate compound, as a crosslinking agent Anurate body (manufactured by Tosoh Corporation, Coronate HX:C/HX) 4 parts by mass (solids 4 parts by mass), 3 parts by mass of dibutyltin dilaurate (1% by mass of ethyl acetate solution) as a crosslinking catalyst (0.03 parts by mass of solids) Was added and mixed and stirred to prepare an acrylic pressure sensitive adhesive 6 solution.

(Preparation of surface protection film)

A surface protective film was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive 6 solution was used.

<Example 13>

(Production of acrylic adhesive 7 solution)

The acrylic polymer (1) solution (40% by mass) was diluted with ethyl acetate to 20% by mass, and 500-10 parts by mass (100 parts by mass of solids) of this solution was used as an alkylene oxide (AO) group-containing compound. As a crosslinking agent, 3.0 parts by mass (solids 3.0 parts by mass) of hexamethylene diisocyanate, manufactured by Daiichi Kogyo Seyakusa, polyoxyethylene nonylpropenylphenyl ether ammonium sulfate, trade name "Aquaron HS-10") Isocyanurate body (manufactured by Tosoh Corporation, 4 parts by mass of coronate HX:C/HX) (4 parts by mass of solids), 3 parts by mass of dibutyltin dilaurate (1% by mass of ethyl acetate solution) as a crosslinking catalyst (0.03 parts by mass of solids) Part) was added and mixed and stirred to prepare an acrylic adhesive 7 solution.

(Preparation of surface protection film)

A surface protective film was produced in the same manner as in Example 1 except that the acrylic adhesive 7 solution was used.

<Comparative Example 1>

(Preparation of surface protection film)

A surface protective film was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive layer had a thickness of 5 μm.

<Comparative Example 2>

(Preparation of surface protection film)

A surface protective film was produced in the same manner as in Example 2, except that the pressure-sensitive adhesive layer had a thickness of 5 μm.

<Comparative Example 3>

(Preparation of surface protection film)

A surface protective film was produced in the same manner as in Example 5, except that the pressure-sensitive adhesive layer had a thickness of 2 μm.

<Comparative Example 4>

(Preparation of surface protection film)

A surface protective film was produced in the same manner as in Example 5, except that the pressure-sensitive adhesive layer had a thickness of 5 μm.

<Comparative Example 5>

(Preparation of surface protection film)

A surface protective film was produced in the same manner as in Example 6, except that the pressure-sensitive adhesive layer had a thickness of 5 μm.

About the surface protection film which concerns on an Example and a comparative example, the compounding content mentioned above, the result of various measurement and evaluation are shown in Tables 1-3, etc.

From Table 3, in all of the examples, since the surface protective film having a thickness of the pressure-sensitive adhesive layer of less than 2 μm was used, it was confirmed that the gauge peeling force was suppressed to be low. On the other hand, in all the comparative examples, it was confirmed that the gauge peeling force was increased by the thickness of the pressure-sensitive adhesive layer being 2 µm or more.

The surface protection film disclosed herein is a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, or the like when manufacturing a thin optical member used as a component, during transportation, or the like. It is suitable as a surface protection film for protection. In particular, it is useful as a surface protection film (optical surface protection film) applied to thin optical members such as polarizing films for liquid crystal display panels, wavelength plates, retardation plates, optical compensation films, brightness enhancement films, light diffusion sheets, and reflective sheets. Do.

1: Surface protection film
2, 50: polarizing film
12: base film
20: adhesive layer
20A: adhesive side
21: first adhesive layer
22, 23: adhesive layer
30, 31: transparent protective film
40: polarizer
60: single-sided adhesive tape
62: adhesive layer (adhesive surface)
64: description

Claims (6)

A surface protection film comprising a base film and an adhesive layer formed on at least one side of the base film, wherein the thickness of the adhesive layer is less than 2 μm. The surface protection film according to claim 1, wherein the peeling force at 90° peeling at 50%RH at 23°C for the triacetylcellulose film is 1 N/50 mm or less. The surface protective film according to claim 1 or 2, wherein the thickness of the base film is 20 μm or more. The surface protection film according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer contains at least one selected from the group consisting of acrylic pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, and silicone pressure-sensitive adhesives. An optical member characterized by being protected by the surface protection film according to any one of claims 1 to 4. The optical member according to claim 5, wherein the optical member is a polarizing film comprising a polarizer, and the thickness of the polarizer is 8 µm or less.

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