JP6931534B2 - Surface protective film and optical members - Google Patents

Description

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

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

On the other hand, the use of such a thin optical member causes a handling problem in the manufacturing process, and countermeasures are required. For example, in the manufacture of a liquid crystal display panel, a polarizing film to be bonded to a liquid crystal cell may be formed by being manufactured in a roll form, then unwound from the roll, and bonded to the liquid crystal cell. It is formed by cutting it into a desired size according to its shape and then bonding it to a liquid crystal cell. Further, the polarizing film is bonded with a surface protective film for the purpose of preventing scratches and stains that occur during transportation (Patent Document 1).

The surface protective film is peeled off and removed when it is no longer needed. However, if the liquid crystal display panel is thin, the liquid crystal display will bend when the surface protective film, which has a heavy peeling force, is peeled off. Problems may occur, such as the surface protective film becoming unable to be peeled off, or the liquid crystal display panel or polarizing film being damaged when peeled off.

Japanese Unexamined Patent Publication No. 2001-305346

Therefore, as a result of diligent research in view of the above circumstances, the present invention does not require a surface protective film for thin optical members and display panels by using a surface protective film using an adhesive layer having a specific thickness. It is an object of the present invention to provide a surface protective film that can be easily peeled off at the stage of becoming, and an optical member protected by the surface protective film.

That is, the surface protective film of the present invention is a base film and a surface protective film in which a pressure-sensitive adhesive layer is formed on at least one side of the base material film, and the thickness of the pressure-sensitive adhesive layer is less than 2 μm. It is characterized by.

The surface protective film of the present invention preferably has a 90 ° peel trigger peeling force of 1 N / 50 mm or less at 23 ° C. and 50% RH with respect to the triacetyl cellulose film.

In the surface protective film of the present invention, the thickness of the base film is preferably 20 μm or more.

In the surface protective film of the present invention, the pressure-sensitive adhesive layer preferably contains at least one selected from the group consisting of an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive.

The optical member of the present invention is preferably protected by the surface protective film.

In the optical member of the present invention, it is preferable that the optical member is a polarizing film containing a polarizer, and the thickness of the polarizer is 8 μm or less.

According to the present invention, by using a surface protective film having an adhesive layer having a specific thickness, it can be easily peeled off when the surface protective film is no longer needed after being attached to a thin optical member or a display panel. , Useful.

It is a schematic cross-sectional view which shows one structural example which attached the surface protection film which concerns on this invention to a polarizing film. It is explanatory drawing which shows the measuring method of the trigger peeling force.

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

<Overall structure of surface protective film>
The surface protective film disclosed herein is generally in the form of an adhesive sheet, an adhesive tape, an adhesive label, an adhesive film, or the like, and in particular, an optical member (for example, a liquid crystal display panel such as a polarizing film or a wavelength plate). It is suitable as a surface protective film that protects the surface of an optical member during processing or transportation of an optical member used as a component or an optical member used for a touch panel display such as a hard coat film). The pressure-sensitive adhesive layer in the surface protective film is typically formed continuously, but is not limited to such a form, and is formed in a regular or random pattern such as a dot shape or a striped shape. It may be an adhesive layer. Further, the surface protective film disclosed herein may be in the form of a roll or in the form of a single leaf.

A typical configuration example of the surface protective film disclosed herein is schematically shown in FIG. The surface protective 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 protective film 1 is used by attaching the pressure-sensitive adhesive layer 20 to an adherend (a protective object, for example, the surface of a transparent protective film 30 which is the surface of an optical member such as a polarizing film). The surface protective film 1 before use (that is, before sticking to the adherend) has a separator in which the surface of the pressure-sensitive adhesive layer 20 (the surface to be stuck to the adherend) is at least the adhesive layer 20 side as a peeling surface. It may be in a form protected by (peeling liner). Alternatively, the surface protective film 1 may be wound in a roll shape so that the pressure-sensitive adhesive layer 20 comes into contact with the back surface of the base film 12 to protect the surface thereof.

Further, as shown in FIG. 1, the polarizing film 2 can be protected by being attached to the surface of the transparent protective film 30 constituting the polarizing film 2 via the adhesive layer 20 constituting the surface protective film 1. .. The transparent protective film 30 and the polarizing element 40 can form a polarizing film via the adhesive layer 22. Further, the transparent protective film 31 is attached to the surface of the polarizer 40 opposite to the surface to which the transparent protective film 30 is attached via the adhesive layer 23, and further, the first adhesive layer 21 is attached. It is also possible to stack and then stack other optical members and the like through the stack.

<Base film for surface protection film>
The surface protective 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, and for example, transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property, and the like are possible. It is preferable to use one having excellent properties such as flexibility and dimensional stability. In particular, since the base film has flexibility, the pressure-sensitive adhesive composition can be applied by a roll coater or the like, and can be wound into a roll shape, which is useful.

As the base film (base material, support), for example, polyester polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate; cellulose polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonate. Based polymer; Acrylic polymer such as polymethylmethacrylate; A plastic film composed of a resin material containing the main resin component (main component of the resin component, typically a component accounting for 50% by mass or more). It 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-based polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers; Examples thereof include those using a vinyl chloride polymer; an amide polymer such as nylon 6, nylon 6, 6, and aromatic polyamide; and the like as a resin material. Still other examples of the resin material include imide-based polymers, sulfone-based polymers, polyether sulfone-based polymers, polyether ether ketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, and vinyl butyral-based polymers. , Arilate-based polymer, polyoxymethylene-based polymer, epoxy-based polymer and the like. It may be a base film composed of a blend of two or more kinds of the above-mentioned polymers.

As the base film, a plastic film made of a transparent thermoplastic resin material can be preferably adopted. Among the plastic films, it is more preferable to use a polyester film. Here, the polyester film is mainly composed of a polymer material (polyester resin) having a main skeleton based on an ester bond such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate. say. Such a polyester film is preferable as a base film for a surface protective film because of its excellent optical properties and dimensional stability.

Various additives such as antistatic agents, antioxidants, ultraviolet absorbers, plasticizers, and colorants (pigments, dyes, etc.) are blended in the resin material constituting the base film, if necessary. May be good. For example, known or conventional surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and undercoating may be applied. Such a surface treatment may be, for example, a treatment for enhancing the adhesion between the base film and the pressure-sensitive adhesive layer (the anchoring property of the pressure-sensitive adhesive layer).

As the surface protective film of the present invention, it is also possible to use a plastic film which has been subjected to antistatic treatment as the base film. It is preferable to use the base film because the charge of the surface protective film itself at the time of peeling can be suppressed. Further, the base film is a plastic film, and by subjecting the plastic film to an antistatic treatment, it is possible to reduce the charge on the surface protective film itself and obtain an excellent antistatic ability on the adherend. The method for imparting the antistatic function is not particularly limited, and a conventionally known method can be used. For example, an antistatic resin, a conductive polymer, or a conductive substance composed of an antistatic agent and a resin component can be used. Examples thereof include a method of applying the contained conductive resin, a method of depositing or plating a conductive substance, and a method of kneading an antistatic agent or 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 and the optical member are improved, which is preferable. In particular, when used for a thin optical member having a thickness of 100 μm or less, a base film having a thickness of 50 μm or more is preferably used in order to secure transportability and bonding workability.

The surface protective film disclosed herein may be implemented in an embodiment including the base film and the pressure-sensitive adhesive layer, as well as other layers. Examples of the other layer include an antistatic layer and an undercoat layer (anchor layer) that enhances the anchoring property of the pressure-sensitive adhesive layer.

<Adhesive layer of surface protective film>
The surface protective 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 from a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition is sticky. As long as it has, it can be used without particular limitation. As the pressure-sensitive adhesive composition, for example, an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a synthetic rubber-based pressure-sensitive adhesive, a natural rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a polyether-based pressure-sensitive adhesive, or the like is used. (Contains), more preferably at least one selected from the group consisting of acrylic pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives, and particularly preferably a pressure-sensitive adhesive polymer. It is to use (contain) an acrylic pressure-sensitive adhesive that uses a (meth) acrylic polymer.

<Acrylic adhesive>
When the pressure-sensitive adhesive layer uses an acrylic pressure-sensitive adhesive, the (meth) acrylic-based polymer, which is a pressure-sensitive adhesive polymer constituting the acrylic pressure-sensitive adhesive, is an alkyl having 1 to 14 carbon atoms as a raw material monomer constituting the pressure-sensitive adhesive polymer. A (meth) acrylic monomer having a group can be used as the main monomer. As the (meth) acrylic monomer, one kind or two or more kinds can be used. By using the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, it becomes easy to control the peeling force (adhesive force) to the adherend (protected body) to be low, and light peeling becomes possible. A surface protective film having excellent properties and removability can be obtained. The (meth) acrylic polymer in the present invention refers to an acrylic polymer and / or a methacrylic polymer, and the (meth) acrylate refers to an acrylate and / or 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, 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 ( Examples include meta) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate. Be done.

Among them, the surface protective film of the present invention includes n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, and 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 A (meth) acrylic monomer having an alkyl group having 4 to 14 carbon atoms such as the above is preferable. In particular, by using a (meth) acrylic monomer having an alkyl group having 6 to 14 carbon atoms, it becomes easy to control the peeling force (adhesive force) to the adherend to be low, and the material has excellent removability. It becomes.

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

Further, in the pressure-sensitive adhesive composition of the present invention, it is preferable that the (meth) acrylic polymer contains a hydroxyl group-containing (meth) acrylic monomer as a raw material monomer. As the hydroxyl group-containing (meth) acrylic monomer, one kind or two or more kinds can be used. By using the hydroxyl group-containing (meth) acrylic monomer, it becomes easier to control cross-linking of the pressure-sensitive adhesive composition, and by extension, a balance between improvement of wettability due to flow and reduction of peeling force (adhesive force) in peeling is achieved. It becomes easier to control.

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-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, and the like. .. In particular, it is preferable to use a hydroxyl group-containing (meth) acrylic monomer having 4 or more carbon atoms in the alkyl group, which facilitates light peeling during high-speed peeling.

The hydroxyl group-containing (meth) acrylic monomer is preferably contained in an amount of 25% by mass or less, more preferably 20% by mass or less, based on 100% by mass of the total amount of the monomer components constituting the (meth) acrylic polymer. More preferably, it is 0.1 to 15% by mass, and most preferably 1 to 10% by mass. When it 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 obtained pressure-sensitive adhesive layer, which is preferable.

In addition, as other polymerizable monomer components, the Tg is set to 0 ° C. or lower (usually -100 ° C. or higher) so that the adhesive performance can be easily balanced, and the glass transition temperature and peeling of the (meth) acrylic polymer are set. A polymerizable monomer for adjusting the property can be used as long as the effect of the present invention is not impaired.

Examples of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms used in the (meth) acrylic polymer and the polymerizable monomer other than the hydroxyl group-containing (meth) acrylic monomer include A carboxyl group-containing (meth) acrylic monomer can be used. By using the carboxyl group-containing (meth) acrylic monomer, it is possible to suppress an increase in the adhesive force of the surface protective film (adhesive layer) over time, and it is possible to suppress the increase in the adhesive force over time, and the re-peelability, the adhesive force increase preventive property, and the work. It is preferable because it has excellent properties and also has excellent shearing force as well as cohesive force of the pressure-sensitive adhesive layer.

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

The amount of the carboxyl group-containing (meth) acrylic monomer is preferably 10% by mass or less, preferably 0.005 to 10% by mass, based on 100% by mass of the total amount of the monomer components constituting the (meth) acrylic polymer. It is more preferably 0.01 to 8% by mass, and most preferably 0.01 to 5% by mass. When it 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 obtained pressure-sensitive adhesive layer, which is preferable.

Further, the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms used in the (meth) acrylic polymer, the hydroxyl group-containing (meth) acrylic monomer, and the carboxyl group-containing (meth) acrylic monomer. As the polymerizable monomer other than the monomer, it can be used without particular limitation as long as it does not impair the characteristics of the present invention. For example, a cohesiveness / heat resistance improving component such as a cyano group-containing monomer, a vinyl ester monomer, and an aromatic vinyl monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, and N-acryloylmorpholin. , A component having a functional group that acts as a cross-linking base point such as a vinyl ether monomer can be appropriately used. Among them, it is preferable to use a cyano group-containing monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, and a nitrogen-containing monomer such as N-acryloylmorpholine. By using the nitrogen-containing monomer, a surface protective film having further excellent shearing force can be obtained, which is useful. As these polymerizable monomers, one kind or two or more kinds can be used.

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, N-dimethylacrylamide, N, N-dimethylmethacrylicamide, N, N-diethylacrylamide, N, N-diethyl. Examples thereof include methacrylamide, N, N'-methylenebisacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylaminopropyl methacrylamide, diacetone acrylamide and the like.

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, N-dimethylaminoethyl (meth) acrylate, and N, N-dimethylaminopropyl (meth) acrylate.

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

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, methyl glycidyl (meth) acrylate, and allyl glycidyl ether.

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

In the present invention, other polymerizable monomers other than the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, the hydroxyl group-containing (meth) acrylic monomer, and the carboxyl group-containing (meth) acrylic monomer are described above. It is preferably 0 to 50% by mass, more preferably 0 to 20% by mass, based on 100% by mass of the total amount of the monomer components constituting the (meth) acrylic polymer. The other polymerizable monomers can be appropriately adjusted to obtain the desired properties.

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

The (meth) acrylic polymer preferably has a weight average molecular weight (Mw) of 100,000 to 3,000,000, more preferably 200,000 to 2,000,000, still more preferably 300,000 to 950,000, and most preferably 300,000 to 750,000. Is. When the weight average molecular weight is less than 100,000, the cohesive force of the pressure-sensitive adhesive layer is reduced, which tends to cause adhesive residue. On the other hand, when the weight average molecular weight exceeds 3 million, the fluidity of the polymer decreases, the wettability to the adherend (for example, the polarizing film) becomes insufficient, and the adherend and the pressure-sensitive adhesive layer of the surface protective film Tends to cause blisters that occur during. The weight average molecular weight is obtained by measuring by GPC (gel permeation chromatography).

The glass transition temperature (Tg) of the (meth) acrylic polymer is preferably 0 ° C. or lower, more preferably −10 ° C. or lower (usually −100 ° C. or higher). When the glass transition temperature is higher than 0 ° C., the polymer does not easily flow, for example, the polarizing film is not sufficiently wetted, which tends to cause blisters generated between the polarizing film and the pressure-sensitive adhesive layer of the surface protective film. There is. In particular, when the glass transition temperature is set to −50 ° C. or lower, it becomes easy to obtain an adhesive layer having excellent wettability to a polarizing film and light peelability. The glass transition temperature of the (meth) acrylic polymer can be adjusted within the above range by appropriately changing the monomer component and composition ratio used.

The polymerization method of the (meth) acrylic polymer is not particularly limited, and can be polymerized by a known method such as solution polymerization, emulsion polymerization, massive polymerization, suspension polymerization, etc., but particularly from the viewpoint of workability and subject matter. Solution polymerization is a more preferable embodiment from the viewpoint of characteristics such as low contamination of the body (protected body). Further, the obtained polymer may be any of a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer and the like.

<Urethane adhesive>
When a urethane-based pressure-sensitive adhesive is used for the pressure-sensitive adhesive layer, any suitable urethane-based pressure-sensitive adhesive may be adopted. Examples of such urethane-based pressure-sensitive adhesives include those made of urethane-based polymers, which are adhesive polymers obtained by reacting a polyol with a polyisocyanate compound. Examples of the polyol include a polyether polyol, a polyester polyol, a polycarbonate polyol, a polycaprolactone polyol, and the like. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, and hexamethylene diisocyanate.

<Silicone adhesive>
When a silicone-based pressure-sensitive adhesive is used for the pressure-sensitive adhesive layer, any suitable silicone-based pressure-sensitive adhesive may be adopted. As such a silicone-based pressure-sensitive adhesive, preferably, one obtained by blending or aggregating a silicone-based polymer which is an adhesive polymer can be adopted.

Examples of the silicone-based pressure-sensitive adhesive include addition-reaction-curable silicone-based pressure-sensitive adhesives and peroxide-curable silicone-based pressure-sensitive adhesives. Among these silicone-based pressure-sensitive adhesives, addition reaction-curable silicone-based pressure-sensitive adhesives are preferable because peroxides (benzoyl peroxide and the like) are not used and decomposition products are not generated.

Examples of the curing reaction of the addition reaction curing type silicone-based pressure-sensitive adhesive include, for example, a method of curing a polyalkyl hydrogen siloxane composition with a platinum catalyst in the case of obtaining a polyalkyl silicone-based pressure-sensitive adhesive.

<Crosslinking agent>
In the surface protective film of the present invention, it is preferable that the pressure-sensitive adhesive composition contains a cross-linking agent. Further, in the present invention, the pressure-sensitive adhesive composition can be used to form a pressure-sensitive adhesive layer. For example, when the pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive containing the (meth) acrylic polymer, the constituent units, the constituent ratios, the selection and addition ratio of the cross-linking agent, etc. of the (meth) acrylic polymer are appropriately selected. By adjusting and cross-linking, a surface protective film (adhesive layer) having more excellent heat resistance can be obtained.

As the cross-linking 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 may be used, and the use of the isocyanate compound is particularly preferable. Further, 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) and dimerate diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI), 1, Alicyclic isocyanates such as 3-bis (isocyanatomethyl) cyclohexane, aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate (XDI), and the isocyanate compounds. Examples thereof include polyisocyanate modified products modified by allophanate bond, biuret bond, isocyanurate bond, uretdione bond, urea bond, carbodiimide bond, uretonimine bond, oxadiazine trione bond and the like. For example, as commercial products, the trade names are Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (all manufactured by Mitsui Chemicals, Inc.), Sumijour T80, Sumijour L, Death Module N3400 (above, Sumika Bayer Urethane Co., Ltd.). (Manufactured by), Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (all manufactured by Tosoh Corporation) and the like. These isocyanate compounds may be used alone or in combination of two or more, or a bifunctional isocyanate compound and a trifunctional or higher isocyanate compound may be used in combination. By using a cross-linking agent in combination, it is possible to achieve both adhesiveness and resilience (adhesiveness to a curved surface), and a surface protective film having more excellent adhesive reliability can be obtained.

Examples of the epoxy compound include N, N, N', N'-tetraglycidyl-m-xylene diamine (trade name: TETRAD-X, manufactured by Mitsubishi Gas Chemical Company, Inc.) and 1,3-bis (N, N-diamine). Glycidylaminomethyl) cyclohexane (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.) and the like can be mentioned.

Examples of the melamine-based resin include hexamethylol melamine. Examples of the aziridine derivative include commercially available commercial products such as HDU, TAZM, and TAZO (all manufactured by Mutual Pharmaceutical Co., Ltd.).

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

The content of the cross-linking agent used in the present invention is, for example, preferably 0.01 to 20 parts by mass and 0.1 to 15 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. More preferably, it is more preferably 0.5 to 10 parts by mass, and most preferably 1 to 6 parts by mass. If the content is less than 0.01 parts by mass, the cross-linking by the cross-linking agent is insufficient, the cohesive force of the obtained pressure-sensitive adhesive layer is reduced, and sufficient heat resistance may not be obtained. It tends to cause adhesive residue. On the other hand, when the content exceeds 20 parts by mass, the cohesive force of the polymer is large, the fluidity is lowered, and the wettability to the adherend (for example, a polarizing film) is insufficient, so that the adherend and the adhesive are used. It tends to cause blisters that occur between the layer (adhesive composition layer). Further, these cross-linking agents may be used alone or in combination of two or more.

The pressure-sensitive adhesive composition may further contain a cross-linking catalyst for more effectively advancing any of the above-mentioned cross-linking reactions. Examples of such cross-linking catalysts include tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris (acetylacetonato) iron (iron (III) acetylacetonate), and tris (hexane-2,4-dionat) iron. Tris (Heptane-2,4-Zionato) Iron, Tris (Heptan-3,5-Zionato) Iron, Tris (5-Methylhexane-2,4-Zionato) Iron, Tris (Octane-2,4-Zionato) Iron , Tris (6-methylheptane-2,4-Dionato) iron, Tris (2,6-dimethylheptane-3,5-Zionato) iron, Tris (Nonan-2,4-Dionato) iron, Tris (Nonan-4) , 6-Dionato) Iron, Tris (2,2,6,6-Tetramethylheptane-3,5-Zionato) Iron, Tris (Tridecane-6,8-Zionato) Iron, Tris (1-phenylbutane-1, 3-Dionato) iron, tris (hexafluoroacetylacetonato) iron, tris (ethylacetate acetate) iron, tris (acetoacetate-n-propyl) iron, tris (isopropylacetate isopropyl) iron, tris (acetoacetate-n-) Butyl) iron, tris (acetoacetate-sec-butyl) iron, tris (acetoacetate-tert-butyl) iron, tris (propionylmethylacetate) iron, tris (propionylacetate ethyl) iron, tris (propionylacetate-n-propyl) ) Iron, tris (isopropylacetic acid propionyl) iron, tris (propionylacetic acid-n-butyl) iron, tris (propionylacetic acid-sec-butyl) iron, tris (propionylacetic acid-tert-butyl) iron, tris (benzylacetate acetate) Iron-based catalysts such as iron, tris (dimethyl malonate) iron, tris (diethyl malonate) iron, trimethoxy iron, triethoxy iron, triisopropoxy iron, and ferric chloride can be used. These cross-linking catalysts may be used alone or in combination of two or more.

The content of the cross-linking catalyst is not particularly limited, but is preferably about 0.0001 to 1 part by mass, and 0.001 to 0.5 parts by mass, for example, with respect to 100 parts by mass of the (meth) acrylic polymer. Parts by mass are more preferred. When it is within the above range, the rate of the cross-linking reaction is high when the pressure-sensitive adhesive layer is formed, and the pot life of the pressure-sensitive adhesive composition is long, which is a preferable embodiment.

Further, the pressure-sensitive adhesive composition may contain an alkylene oxide (AO) group-containing compound. As a result, the wettability to the adherend can be improved, the adhesiveness to the adherend can be improved, and it becomes easy to suppress the mixing of air bubbles and the like generated during the bonding. ..

Specific examples of the alkylene oxide (AO) group-containing compound include polyoxyalkylene alkylamine, polyoxyalkylenediamine, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene alkylphenyl ether, and polyoxy. Nonionic surfactants such as alkylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyalkylene alkyl allyl ether, polyoxyalkylene alkyl phenyl allyl ether, polyalkylene glycol dialkyl ester, polyalkylene glycol diaryl ester; polyoxyalkylene alkyl ether Sulfate ester salt, polyoxyalkylene alkyl ether sulfate ester salt, polyoxyalkylene alkyl ether phosphoric acid ester salt, polyoxyalkylene alkyl phenyl ether sulfate ester salt, polyoxyalkylene alkyl allyl phenyl ether sulfate ester salt, polyoxyalkylene alkyl phenyl ether Anionic surfactants such as phosphate ester salts; in addition, cationic surfactants having polyoxyalkylene chains (polyalkylene oxide chains), amphoteric surfactants, polyether compounds having polyoxyalkylene chains (and Examples thereof include an ether compound having a polyoxyalkylene chain (including a derivative thereof), an acrylic compound having a polyoxyalkylene chain (including a derivative thereof), and the like. Further, the polyoxyalkylene chain-containing monomer may be blended with the acrylic polymer as the polyoxyalkylene chain-containing compound. Such a polyoxyalkylene chain-containing compound may be used alone or in combination of two or more.

Specific examples of the ether compound having a polyoxyalkylene chain include a block copolymer of polypropylene glycol (PPG) -polyethylene glycol (PEG), a block copolymer of PPG-PEG-PPG, and a block of PEG-PPG-PEG. Examples include block polymers. Derivatives of the ether compound having a polyoxyalkylene chain include an oxypropylene group-containing compound having an etherified terminal (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.) and an oxypropylene group having an acetylated terminal. Examples include compounds (terminal acetylated PPG, etc.), and the like.
Further, specific examples of the ester compound having a polyoxyalkylene chain include an ester compound having an oxyalkylene group. As the oxyalkylene group, the number of moles of the oxyalkylene unit added is preferably 1 to 50, more preferably 2 to 30, and even more preferably 2 to 20 from the viewpoint of coordination of the ionic compound. 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.
Further, specific examples of the acrylic compound having a polyoxyalkylene chain include a (meth) acrylate polymer having an oxyalkylene group. As the oxyalkylene group, the number of moles of the oxyalkylene unit added is preferably 1 to 50, more preferably 2 to 30, and even more preferably 2 to 20 from the viewpoint of coordination of the ionic compound. Further, the terminal of the oxyalkylene chain may remain as a hydroxyl group or may be substituted with an alkyl group, a phenyl group or the like.

The (meth) acrylate polymer having an 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. Examples of the ethylene glycol group-containing (meth) acrylate include methoxy-polyethylene glycol (meth) acrylate type such as methoxy-diethylene glycol (meth) acrylate and methoxy-triethylene glycol (meth) acrylate, and ethoxy-diethylene glycol (meth). Acrylate, ethoxy-polyethylene glycol (meth) acrylate such as ethoxy-triethylene glycol (meth) acrylate, butoxy-polyethylene glycol (meth) acrylate such as butoxy-diethylene glycol (meth) acrylate, butoxy-triethylene glycol (meth) acrylate Type, phenoxy-polyethylene glycol (meth) acrylate such as phenoxy-diethylene glycol (meth) acrylate, phenoxy-triethylene glycol (meth) acrylate, 2-ethylhexyl-polyethylene glycol (meth) acrylate, nonylphenol-polyethylene glycol (meth) acrylate Examples thereof include a methoxy-polypropylene glycol (meth) acrylate type such as a methoxy-dipropylene glycol (meth) acrylate.

Further, as the monomer unit (component), other monomer units (components) other than the (meth) acrylic acid alkylene oxide can also be used. Specific 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, isononyl (meth) acrylate, n-decyl (meth) ) Acrylate and / or methacrylate having an alkyl group having 1 to 14 carbon atoms such as acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate. Can be mentioned.

Further, 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, and fragrance. Group 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-acryloylmorpholine , Vinyl ethers and the like can also be used as appropriate.

The number average molecular weight (Mn) of the alkylene oxide (AO) group-containing compound is preferably 50,000 or less, preferably 200 to 30,000, more preferably 200 to 10,000, and usually 200 to 5,000. Is preferably used. If Mn is more than 50,000, the compatibility with the acrylic polymer is lowered and the pressure-sensitive adhesive layer tends to be whitened. If Mn is less than 200, contamination by the polyoxyalkylene compound may easily occur. Here, Mn means a polystyrene-equivalent value obtained by gel permeation chromatography (GPC).

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

Further, the pressure-sensitive adhesive composition may contain other known additives, for example, powders such as lubricants, colorants and pigments, plasticizers, tackifiers, low molecular weight polymers and surface lubrication. Agents, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, UV absorbers, polymerization inhibitors, silane coupling agents, antioxidants, crosslink retardants, inorganic or organic fillers, metal powders, particles It can be added as appropriate depending on the intended use of the shape, foil-like material, and the like.

<Adhesive layer and surface protective film>
The surface protective film of the present invention is formed by forming the pressure-sensitive adhesive layer on at least one side of the base film, and at that time, the pressure-sensitive adhesive composition is crosslinked after the pressure-sensitive adhesive composition is applied. Is common, but after forming a pressure-sensitive adhesive layer composed of a cross-linked pressure-sensitive adhesive composition on a separator provided with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based mold release agent layer, a base material is used. It is also possible to transfer to a film or the like.

The method of forming the pressure-sensitive adhesive layer on the base film is not particularly limited. For example, the pressure-sensitive adhesive composition (solution) is applied to the base film, and a polymerization solvent or the like is dried and removed to form the pressure-sensitive adhesive layer. It is produced by forming it on a base film. After that, curing may be performed for the purpose of adjusting the component transfer of the pressure-sensitive adhesive layer, adjusting the cross-linking reaction, and the like. Further, when the pressure-sensitive adhesive composition is applied onto the base film to prepare a surface protective film, one or more kinds other than the polymerization solvent are contained in the pressure-sensitive adhesive composition so that the pressure-sensitive adhesive composition can be uniformly applied on the base film. The solvent may be newly added.

Further, as a method for forming the pressure-sensitive adhesive layer when manufacturing the surface protective film of the present invention, a known method used for manufacturing pressure-sensitive adhesive tapes is used. Specific examples thereof include a roll coat, a gravure coat, a reverse coat, a roll brush, a spray coat, an air knife coat method, and an extrusion coat method using a die coater or the like.

In the surface protective 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, and further preferably 0. It is 4 to 1.2 μm, particularly preferably 0.5 to 1 μm. When the thickness of the adhesive layer is within the above range, the trigger peeling force becomes low, and the adhesive layer can be easily peeled off when the surface protective film is no longer needed after being attached to a thin optical member or display panel. ,preferable.

The pressure-sensitive adhesive layer has a shear storage elastic modulus (G') at 23 ° C. of ^{preferably 1.0 × 10 4 to} 1.0 × 10 ⁷ Pa, and more preferably 1.0 × 10 ⁵ to. It is 5.0 × 10 ⁶ Pa, more preferably 3.0 × 10 ^{5 to} 5.0 × 10 ⁶ Pa. By adjusting within the above range, the trigger peeling force can be suppressed to a low level, the adhesion to the surface of the adherend can be ensured, and the bonding can be easily performed, which is a preferable embodiment.

Further, the 90 ° peel trigger peeling force of the surface protective film (adhesive layer) at 23 ° C. and 50% RH with respect to the triacetyl cellulose film (polarizing film) is preferably 1 N / 50 mm or less, more preferably. , 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. If the trigger peeling force exceeds 1N / 50 mm, peeling resistance is applied when the surface protective film is peeled from the polarizing film with the pickup tape, which makes peeling difficult, which is not preferable.

The surface protective film of the present invention preferably has a total thickness of 20 to 400 μm, more preferably 30 to 200 μm, further preferably 40 to 150 μm, and particularly preferably 50 to 100 μm. .. When it is within the above range, it is excellent in adhesive properties (removability, adhesiveness, etc.), workability, and appearance characteristics, and is a preferable embodiment. The total thickness means the total thickness including all the layers when the base film, the pressure-sensitive adhesive layer and other layers are present.

<Separator>
If necessary, the surface protective film of the present invention can have a separator attached to the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive surface of the pressure-sensitive adhesive layer.

Paper and a plastic film are examples of the material constituting the separator, and the plastic film is preferably used because of its excellent surface smoothness. The film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and is, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-weight. Examples thereof include a coalesced 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 about 5 to 200 μm, preferably about 10 to 100 μm. When it is within the above range, it is preferable because it is excellent in sticking workability to the pressure-sensitive adhesive layer and peeling workability from the pressure-sensitive adhesive layer. If necessary, the separator may be used for mold release and antifouling treatment with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based mold release agent, silica powder, etc., as well as a coating type, a kneading type, and a vapor deposition type. It is also possible to carry out antistatic treatment such as.

<Optical member>
The optical member of the present invention is preferably protected by the surface protective film. The surface protective film can be used for surface protection applications such as processing, transportation, and shipping, and is useful for protecting the surface of the optical member (polarizing film or the like). In particular, it is very useful for thin optical members (polarizing film, etc.) and display panels because the surface protective film can be easily peeled off when it is no longer needed.

The optical member of the present invention is a polarizing film containing a polarizing element, and the thickness of the polarizing element is preferably 8 μm or less. Since the thickness of the polarizer is as thin as 8 μm or less, it is a useful and preferable embodiment for an optical member (polarizing film) that is required to be thinned in recent years.

<Polarizing film>
As the polarizing film, a polarizing film and a film in which a transparent protective film is laminated on at least one side of the polarizing element and a first pressure-sensitive adhesive layer is laminated on at least one side of the polarizing film can be used.

<Polarizer>
As the polarizer, one using a polyvinyl alcohol-based resin is used. Examples of the polarizer include a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene-vinyl acetate copolymerization system partially saponified film, and a bicolor property of iodine or a bicolor dye. Examples thereof include a uniaxially stretched film by adsorbing a substance, a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol and a dehydrogenated product of polyvinyl chloride. Among these, a polarizer made of a polyvinyl alcohol-based film and a dichroic substance such as iodine is preferable.

The polarizer in which the polyvinyl alcohol-based film is dyed with iodine and uniaxially stretched can be produced, for example, by dyeing the polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times the original length. .. If necessary, boric acid, zinc sulfate, zinc chloride and the like may be contained, or the mixture 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 with water before dyeing. In addition to being able to clean the surface of the polyvinyl alcohol film and blocking inhibitors by washing the polyvinyl alcohol film with water, it also has the effect of preventing non-uniformity such as uneven dyeing by swelling the polyvinyl alcohol film. be. Stretching may be performed after dyeing with iodine, stretching while dyeing, or stretching and then dyeing with iodine. It can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

The thickness of the polarizer is preferably 8 μm or less, more preferably 7 μm or less, and further preferably 6 μm or less from the viewpoint of thinning. On the other hand, the thickness of the polarizer is preferably 2 μm or more, more preferably 3 μm or more. Such a thin polarizing element has less uneven thickness, excellent visibility, and less dimensional change, so that it has excellent durability against thermal shock. Typical examples of the thin polarizer include Patent No. 4751486, Patent No. 4751481, Patent No. 4815544, Patent No. 5048120, International Publication No. 2014/07759, International Publication No. 2014/07759. Examples thereof include the thin polarizer described in Japanese Patent Publication No. 2014/077636 and the like, or the thin polarizer obtained from the manufacturing method described therein.

The polarizer has an optical characteristic represented by a simple substance transmittance T and a degree of polarization P of the following equation P>-(100.929T-42.4-1) × 100 (however, T <42.3), or , P ≧ 99.9 (however, T ≧ 42.3). A polarizer configured to satisfy the above conditions primarily has the performance required for a display for a liquid crystal television using a large display element. Specifically, the contrast ratio is 1000: 1 or more and the maximum brightness is 500 cd / m ² or more. As another use, for example, it is attached to the visual side of an organic EL cell.

The thin polarizer is patented in Patent No. 4751486, in that it can be stretched at a high magnification and the polarization performance can be improved even in a manufacturing method including a step of stretching in a laminated state and a step of dyeing. Those obtained by a production method including a step of stretching in an aqueous boric acid solution as described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544 are preferable, and particularly described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544. It is preferably obtained by a production method including a step of auxiliary stretching in the air before stretching in a certain boric acid aqueous solution. These thin polarizers can be obtained by a production method including a step of stretching a polyvinyl alcohol-based resin (hereinafter, also referred to as PVA-based resin) layer and a resin base film for stretching in a laminated state and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching because it is supported by the resin base film for stretching.

(Transparent protective film)
The material constituting the transparent protective film is not particularly limited, but is preferably one having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, 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, and styrene such as polystyrene and acrylonitrile-styrene copolymer (AS resin). Examples thereof include based polymers and polystyrene polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclo- or norbornene structure, polyolefin-based polymers such as ethylene / propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamide, imide-based polymers, and sulfone-based polymers. , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, allylate polymer, polyoxymethylene polymer, epoxy polymer, or the above. Polymer blends and the like are also examples of polymers that form the transparent protective film. These transparent protective films are usually attached to the polarizer by an adhesive layer. In addition, the transparent protective film may contain one or more kinds of arbitrary suitable additives. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, a color retardant, a flame retardant, a nucleating agent, an antistatic agent, a pigment, a colorant and the like.

The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by mass, more preferably 50 to 99% by mass, still more preferably 60 to 98% by mass, and particularly preferably 70 to 97% by mass. be. When the content of the thermoplastic resin in the transparent protective film is 50% by mass or less, the high transparency inherent in the thermoplastic resin may not be sufficiently exhibited.

The thickness of the transparent protective film can be appropriately determined, but is generally preferably 5 to 50 μm, more preferably 5 to 45 μm, in terms of workability such as strength and handleability, and thin layer property. Is preferable.

A functional layer such as a hard coat layer, an antireflection layer, an anti-sticking layer, a diffusion layer or an anti-glare layer can be provided on the surface of the transparent protective film to which the polarizer is not adhered. The functional layers such as the hard coat layer, the antireflection layer, the sticking prevention layer, the diffusion layer and the antiglare layer can be provided on the transparent protective film itself, and are separately provided separately from the transparent protective film. You can also do it.

The transparent protective film and the polarizer are laminated via an intervening layer such as an adhesive layer, an adhesive layer, and an undercoat layer (primer layer). At this time, it is desirable that both are laminated without an air gap by an intervening layer.

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

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

The active energy ray-curable adhesive is an adhesive whose curing proceeds by active energy rays such as electron beam and ultraviolet rays (radical curing type, cationic curing type), and is, for example, an electron beam curing type and an ultraviolet curing type. Can be used in. As the active energy ray-curable adhesive, for example, a photoradical curable adhesive can be used. When a photoradical-curable active energy ray-curable adhesive is used as an ultraviolet curable type, the adhesive contains a radical-polymerizable compound and a photopolymerization initiator.

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

When a water-based adhesive or the like is used, the adhesive is preferably applied so that the thickness of the finally formed adhesive layer is 30 to 300 nm, more preferably 60 to 150 nm. Is. On the other hand, when an active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.2 to 20 μm.

When laminating the polarizer and the transparent protective film, an easy-adhesion layer can be provided between the transparent protective film and the adhesive layer. The easy-adhesion layer can be formed of, for example, various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based material, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like. These polymer resins may be used alone or in combination of two or more. Further, other additives may be added to form the easy-adhesion layer. Specifically, a tackifier, an ultraviolet absorber, an antioxidant, a stabilizer such as a heat-resistant stabilizer, or the like may be used.

The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive (adhesive composition). Various adhesives can be used as the adhesive, for example, rubber adhesive, acrylic adhesive, silicone adhesive, urethane adhesive, vinyl alkyl ether adhesive, polyvinylpyrrolidone adhesive, poly. Examples include acrylamide-based adhesives and cellulose-based adhesives. A sticky base polymer is selected according to the type of the pressure-sensitive adhesive. Among the above-mentioned adhesives, acrylic adhesives are preferably used because they are excellent in optical transparency, exhibit appropriate wettability, cohesiveness and adhesive properties, and are excellent in weather resistance and heat resistance. NS.

The undercoat 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 a certain degree of 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, etc. 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 can be used on the surface of the front first pressure-sensitive adhesive layer opposite to the surface in contact with the polarizing film. (For example, a retardation film, a liquid crystal display device, etc.) and the like can be laminated. Further, the first pressure-sensitive adhesive layer can be directly laminated on the undercoat layer laminated on the polarizer. An appropriate pressure-sensitive adhesive can be used for forming the first pressure-sensitive adhesive layer, and the type thereof is not particularly limited. As adhesives, rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone adhesives, polyacrylamide adhesives, Examples include cellulose-based adhesives. Among these adhesives, those having excellent optical transparency, exhibiting appropriate wettability, cohesiveness and adhesiveness, and excellent weather resistance and heat resistance are preferably used. An acrylic pressure-sensitive adhesive is preferably used to exhibit such characteristics.

As a method of forming the first pressure-sensitive adhesive layer, for example, the pressure-sensitive adhesive is applied to a peeled separator, a polymerization solvent or the like is dried and removed to form a pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive is transferred to a polarizing film. It is produced by a method of applying the pressure-sensitive adhesive to a polarizing film and drying and removing a polymerization solvent or the like to form a pressure-sensitive adhesive layer on a polarizer or the like. When applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be newly added as appropriate. As the peeling-treated separator, a silicone separator is preferably used.

In the step of applying the pressure-sensitive adhesive of the present invention on such a separator and drying it to form a pressure-sensitive adhesive layer, as a method of drying the pressure-sensitive adhesive, an appropriate method can be appropriately adopted depending on the purpose. Preferably, a method of overheating and drying the coating film is used. The heat-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 in the above range, a pressure-sensitive adhesive having excellent adhesive properties can be obtained.

Various methods are used as the method for forming the first pressure-sensitive adhesive layer. Specifically, for example, 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. Examples include a method such as an extrusion coating method.

What is the thickness of the first pressure-sensitive adhesive layer? It 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 pressure-sensitive adhesive layer until it is put into practical use. Examples of the constituent material of the separator include plastic films such as polyethylene, polypropylene, polyethylene terephthalate and polyester film, porous materials such as paper, cloth and non-woven fabric, nets, foam sheets, metal foils, and laminates thereof. An appropriate thin leaf body can be mentioned, but a plastic film is preferably used because of its excellent surface smoothness. The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, and vinyl chloride are all used. Examples thereof include polymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, and ethylene-vinyl acetate copolymer films.

If necessary, the separator may be used for mold release and antifouling treatment with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based mold release agent, silica powder, etc., as well as a coating type, a kneading type, and a vapor deposition type. It is also possible to perform antistatic treatment such as. In particular, the peelability from the first pressure-sensitive adhesive layer can be further enhanced by appropriately performing a peeling treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment on the surface of the release film.

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

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 such specific examples. In addition, "part" and "%" in the following description are based on mass unless otherwise specified. In addition, the blending amount (addition amount) in the table is 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 a GPC apparatus (HLC-8220 GPC) manufactured by Tosoh Corporation. The measurement conditions are as follows.
Sample concentration: 0.2% by mass (THF solution)
Sample injection volume: 10 μl
Eluent: THF
Flow velocity: 0.6 ml / min
Measurement temperature: 40 ° C
column:
Sample column; TSKguardcolum SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column; TSKgel SuperH-RC (1)
Detector: Differential Refractometer (RI)
The weight average molecular weight was determined by polystyrene conversion value.

<Glass transition temperature (Tg)>
The glass transition temperature Tg (° C.) of the polymer was determined by the following formula using the following literature values as the glass transition temperature Tgn (° C.) of the homopolymer by each monomer.
Formula: 1 / (Tg + 273) = Σ [Wn / (Tgn + 273)]
[In the formula, Tg (° C.) is the glass transition temperature of the copolymer, Wn (-) is the mass fraction of each monomer, Tgn (° C.) is the glass transition temperature of the homopolymer by each monomer, and n is the type of each monomer. Represents. ]
Reference value:
2-Ethylhexyl acrylate (2EHA): -70 ° C
Butyl acrylate (BA): -55 ° C
2-Hydroxyethyl acrylate (HEA): -15 ° C.
Acrylic acid (AA): 106 ° C

As literature values, "synthesis / design of acrylic resin and development of new applications" (published by the Publishing Department of the Central Management Development Center), "Polymer Handbook" (John Wiley & Sons), and monomer manufacturer Kadalog values were referred to.

The glass transition temperature (Tg) (° C.) of the (meth) acrylic polymer obtained from a monomer whose literature value is unknown can be determined by dynamic viscoelasticity measurement by the following procedure.
First, a sheet of (meth) acrylic polymer having a thickness of 20 μm was laminated to a thickness of about 2 mm, which was punched to φ7.9 mm to prepare a columnar pellet, which was used as a sample for measuring the glass transition temperature (Tg). bottom.
Using the above measurement sample, fix the above measurement sample on a jig of φ7.9 mm parallel plate, and use a dynamic viscoelasticity measuring device (ARES, manufactured by Leometrics) to determine the temperature dependence of the loss elastic modulus G''. The temperature at which the G ″ curve obtained was maximized was defined as the glass transition temperature (Tg) (° C.). The measurement conditions are as follows.
Measurement: Shear mode Temperature range: -70 ° C to 150 ° C
Temperature range: 5 ° C / min
Frequency: 1Hz

<Storage modulus (G')>
Sheets of a pressure-sensitive adhesive layer having a thickness of 20 μm were laminated to obtain a thickness of about 2 mm, which was punched to φ7.9 mm to prepare columnar pellets, which were used as samples for measuring the storage elastic modulus.
The above measurement sample is fixed to a jig of a φ7.9 mm parallel plate, and the storage elastic modulus (Pa) at a temperature of 23 ° C. and a frequency of 1 Hz is measured with a dynamic viscoelasticity measuring device (ARES, manufactured by Leometrics). bottom. The storage elastic modulus was measured for those using an acrylic pressure-sensitive adhesive.

<Thickness measurement>
Using a transmission electron microscope (H-7650 manufactured by Hitachi, Ltd.), the cross section of the surface protective film was observed, and the thickness of the pressure-sensitive adhesive layer and the like was measured.

<Collecting force (pickup force)>
As shown in FIG. 2, the surface protective film 1 according to each example is cut into a size of 50 mm in width and 100 mm in length, and the adhesive surface 20A of the surface protective film 1 is placed on the following single protective polarizing film 50 at a pressure of 0.25 MPa. , Crimped at a speed of 0.3 m / min. Single-sided adhesive tape (manufactured by Nichiban Co., Ltd., trade name "Cellotape (registered trademark)", width 24 mm) 60 was cut to a length of 50 mm. The adhesive surface of this adhesive tape was crimped with a hand roller on the center of the back surface of the surface protective film 1 having a width of 50 mm so that the end portion protruded by 30 mm. This was allowed to stand for 10 seconds under the conditions of 23 ° C. and 50% RH. After that, when the single-sided adhesive tape 60 was peeled off in the 90 ° direction at a speed of 0.3 m / min by an autograph, the maximum stress applied at the beginning of the peeling was used as a trigger peeling force (N / 50 mm).

<Manufacturing of polarizing film>
(Making a polarizer)
Amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a water absorption rate of 0.75% and a Tg of 75 ° C. Alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (degree of polymerization 1200, degree of acetoacetyl modification 4.6%, degree of saponification 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. , Trade name "Gosefimer Z200") at a ratio of 9: 1 was applied and dried at 25 ° C. to form a PVA-based resin layer having a thickness of 11 μm to prepare a laminate.
The obtained laminate was uniaxially stretched at the free end in the longitudinal direction (longitudinal direction) 2.0 times between rolls having different peripheral speeds in an oven at 120 ° C. (aerial auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 30 ° C. (an aqueous boric acid solution obtained by blending 4 parts by mass of boric acid with 100 parts by mass of water) for 30 seconds (insolubilization treatment).
Next, the polarizing plate was immersed in a dyeing bath having a liquid temperature of 30 ° C. while adjusting the iodine concentration and the immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 parts by mass of iodine was mixed with 100 parts by mass of water, and 1.0 part by mass of potassium iodide was mixed and immersed in the obtained iodine aqueous solution for 60 seconds (dyeing treatment). ..
Then, it was immersed in a cross-linked bath at a liquid temperature of 30 ° C. (an aqueous boric acid solution obtained by blending 3 parts by mass of potassium iodide and 3 parts by mass of boric acid with respect to 100 parts by mass of water) for 30 seconds. (Crossing treatment).
Then, the laminate is immersed in an aqueous solution of boric acid having a liquid temperature of 70 ° C. (an aqueous solution obtained by blending 4 parts by mass of boric acid and 5 parts by mass of potassium iodide with respect to 100 parts by mass of water). However, uniaxial stretching was performed between rolls having different peripheral speeds so that the total stretching ratio was 5.5 times in the longitudinal direction (longitudinal direction) (underwater stretching treatment).
Then, the laminate was immersed in a washing bath at a liquid temperature of 30 ° C. (an aqueous solution obtained by blending 4 parts by mass of potassium iodide with respect to 100 parts by mass of water) (cleaning treatment). From the above, an optical film laminate containing 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 stirrer, 100 parts of butyl acrylate, 3 parts of acrylate, 0.1 part of 2-hydroxyethyl acrylate and 2,2'-azobisisobuty 0.3 part of ronitrile was added together with ethyl acetate to prepare a solution. Then, 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 having a solid content concentration adjusted to 30%.
A cross-linking agent containing 0.5 part of a compound having an isocyanate group as a main component with respect to 100 parts of the solid content of the acrylic polymer solution (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L"). And 0.075 parts of γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name “KMB-403”) are blended in this order as a silane coupling agent to prepare an adhesive solution. Was prepared. The above pressure-sensitive adhesive solution is applied to the surface of a release sheet (separator) made of a stripped polyethylene terephthalate film (thickness 38 μm) so that the thickness after drying is 25 μm, and dried to form a pressure-sensitive adhesive layer. Formed.

(Making a single protective polarizing film)
A 40 μm-thick triacetyl cellulose (TAC) film (trade name “TAC film KC4UY” manufactured by Konica Minolta Opto) was attached to the polarizer side of the optical film laminate via a vinyl alcohol-based adhesive. Next, the amorphous PET base material was peeled off, and the pressure-sensitive adhesive layer was attached to the peeled surface to prepare a single-protective polarizing film.

<Preparation of acrylic polymer (1)>
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler, 95 parts by mass of 2-ethylhexyl acrylate (2EHA), 5 parts by mass of 2-hydroxyethyl acrylate (HEA), and 2 as a polymerization initiator. , 2'-Azobisisobutyronitrile 0.2 parts by mass and ethyl acetate 150 parts by mass were charged, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was maintained at around 65 ° C. for 6 hours polymerization. The reaction was carried out to prepare an acrylic polymer (1) solution (40% by mass). The weight average molecular weight (Mw) of the acrylic polymer (1) was 550,000, and the glass transition temperature (Tg) was −68 ° C.

<Preparation of acrylic polymer (2)>
95 parts by mass of butyl acrylate (BA), 5 parts by mass of acrylic acid (AA), 2,2'-azo as a 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 of bisisobutyronitrile and 234 parts by mass of ethyl acetate were charged, nitrogen gas was introduced while gently stirring, the liquid temperature in the flask was maintained at around 63 ° C., and the polymerization reaction was carried out for 7 hours to carry out an acrylic reaction. A solution (30% by mass) of the system polymer (2) was prepared. The weight average molecular weight (Mw) of the acrylic polymer (2) was 600,000, and the glass transition temperature (Tg) was −50 ° C.

[Preparation of 1 solution of acrylic adhesive]
The above acrylic polymer (1) solution (40% by mass) was diluted with ethyl acetate to 20% by mass, and 500 parts by mass (solid content 100 parts by mass) of this solution was added as a cross-linking agent to trimethylo, which is a trifunctional isocyanate compound. Lupropane / tolylene diisocyanate trimeric adduct (manufactured by Toso Co., Ltd., Coronate L: C / L) 2.7 parts by mass (solid content 2 parts by mass), dibutyltin dilaurate (1% by mass ethyl acetate) as a cross-linking catalyst Solution) 3 parts by mass (solid content 0.03 parts by mass) was added, and mixing and stirring were carried out to prepare one solution of acrylic pressure-sensitive adhesive.

[Preparation of 2 solutions of acrylic adhesive]
The above acrylic polymer (1) solution (40% by mass) is diluted with ethyl acetate to 20% by mass, and 500 parts by mass (solid content 100 parts by mass) of this solution is added to hexamethylene, which is a trifunctional isocyanate compound, as a cross-linking agent. Isocyanurate of diisocyanate (manufactured by Toso Co., Ltd., Coronate HX: C / HX) 4 parts by mass (solid content 4 parts by mass), dibutyltin dilaurate (1 mass% ethyl acetate solution) 3 parts by mass (solid content 0. 03 parts by mass) was added, and the mixture was mixed and stirred to prepare two solutions of acrylic pressure-sensitive adhesive.

[Preparation of 3 solutions of acrylic adhesive solution]
The above acrylic polymer (2) solution (30% by mass) was diluted to 20% by mass with ethyl acetate, and an epoxy compound (manufactured by Mitsubishi Gas Chemicals Co., Ltd.) was added to 500 parts by mass (100 parts by mass of solid content) of this solution as a cross-linking agent. , TETRAD-C: T / C) 5 parts by mass (5 parts by mass of solid content) was added, and the mixture was mixed and stirred to prepare 3 solutions of acrylic pressure-sensitive adhesive.

<Example 1>
[Preparation of surface protection film]
One solution of the above acrylic pressure-sensitive adhesive was applied to one side of a polyester film (Toyobo Co., Ltd., E5000) having a thickness of 38 μm and heated at 130 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 1 μm. Next, a silicone-treated surface of a polyethylene terephthalate film (thickness 25 μm) having been treated with silicone on one side was bonded to the surface of the pressure-sensitive adhesive layer to prepare a surface protective 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 above acrylic pressure-sensitive adhesive solution 2, a pressure-sensitive adhesive layer having a thickness of 1.9 μm was applied and formed on one side of a polyester film (Toyobo Co., Ltd., E5000) having a thickness of 50 μm, which is a base film. A surface protective film was prepared in the same manner as in Example 2.

<Example 4>
[Preparation of surface protection film]
The acrylic pressure-sensitive adhesive solution 3 was applied to one side of a polyester film (Toyobo Co., Ltd., E5000) having a thickness of 38 μm and heated at 130 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 0.5 μm. Next, a silicone-treated surface of a polyethylene terephthalate film (thickness 25 μm) having been treated with silicone on one side was bonded to the surface of the pressure-sensitive adhesive layer to prepare a surface protective film.

<Examples 5 to 9>
Using the acrylic pressure-sensitive adhesive 3 solution in the same manner as in Example 4, the pressure-sensitive adhesive layers of each thickness (0.5 μm, 1 μm, 1.9 μm) shown in Table 3 were applied to each thickness (25 μm, 38 μm). , 50 μm, 75 μm) polyester film (Toyobo, E5100: 38 μm, 50 μm, 75 μm base film, E5101: 25 μm base film) was applied and formed on one side to prepare a surface protective film.

<Example 10>
[Preparation of 4 urethane adhesive solutions]
As a polyol, Preminol S3011 (Mn = 10000, manufactured by Asahi Glass Co., Ltd.), which is a polyol having three hydroxyl groups, 85 parts by mass, and Sanniks GP3000 (Mn = 3000, manufactured by Sanyo Kasei Co., Ltd.), which is a polyol having three hydroxyl groups, 13 By mass, 2 parts by mass of Sanniks GP1000 (Mn = 1000, manufactured by Sanyo Kasei Co., Ltd.), which is a polyol having three hydroxyl groups, and 18 parts by mass of an isocyanate compound (Coronate HX: C / HX, manufactured by Toso Co., Ltd.) as a cross-linking agent. 0.04 parts by mass of iron (III) acetylacetonate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was blended as a catalyst, and 210 parts by mass of ethyl acetate as a diluting solvent to obtain 4 solutions of urethane-based pressure-sensitive adhesive.

[Preparation of surface protection film]
A surface protective film was prepared by the same method and conditions as in Example 1 except that the above urethane adhesive 4 solution was used.

<Example 11>
[Preparation of 5 solutions of silicone adhesive]
As a silicone-based adhesive, "X-40-3229" (solid content 60% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.) is 100 parts by mass in solid content, and as a platinum catalyst, "CAT-PL-50T" (Shin-Etsu Chemical Co., Ltd.) (Manufactured) 0.5 parts by mass and 100 parts by mass of toluene as a solvent were blended to obtain 5 solutions of silicone-based pressure-sensitive adhesive.

[Preparation of surface protection film]
A surface protective film was prepared by the same method and conditions as in Example 1 except that the above silicone-based pressure-sensitive adhesive 5 solution was used.

<Example 12>
[Preparation of 6 solutions of acrylic adhesive]
The above acrylic polymer (1) solution (40% by mass) is diluted to 20% by mass with ethyl acetate, and 25R-1 as an alkylene oxide (AO) group-containing compound is added to 500 parts by mass (100 parts by mass of solid content) of this solution. (Polyoxyethylene-polyoxypropylene block polymer manufactured by ADEKA, trade name "Adecapluronic 25R-1") 0.5 parts by mass (solid content 0.5 parts by mass), a trifunctional isocyanate compound as a cross-linking agent. Isocyanurate polymer of hexamethylene diisocyanate (manufactured by Toso Co., Ltd., Coronate HX: C / HX) 4 parts by mass (solid content 4 parts by mass), dibutyltin dilaurate (1 mass% ethyl acetate solution) 3 parts by mass (solid content) as a cross-linking catalyst 0.03 parts by mass) was added, and the mixture was mixed and stirred to prepare 6 solutions of acrylic pressure-sensitive adhesive.

[Preparation of surface protection film]
A surface protective film was prepared in the same manner as in Example 1 except that the above 6 solutions of the acrylic pressure-sensitive adhesive were used.

<Example 13>
[Preparation of 7 solutions of acrylic adhesive]
The above acrylic polymer (1) solution (40% by mass) is diluted with ethyl acetate to 20% by mass, and in 500 parts by mass (100 parts by mass of solid content) of this solution, HS-10 is used as an alkylene oxide (AO) group-containing compound. (Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene nonylpropenylphenyl ether ammonium sulfate, trade name "Aqualon HS-10") 3.0 parts by mass (solid content 3.0 parts by mass), as a cross-linking agent with a trifunctional isocyanate compound Isocyanurate compound of a certain hexamethylene diisocyanate (manufactured by Toso Co., Ltd., Coronate HX: C / HX) 4 parts by mass (solid content 4 parts by mass), dibutyltin dilaurate (1 mass% ethyl acetate solution) 3 parts by mass (solid) as a cross-linking catalyst (0.03 parts by mass) was added, and the mixture was mixed and stirred to prepare 7 solutions of acrylic pressure-sensitive adhesive.

[Preparation of surface protection film]
A surface protective film was produced in the same manner as in Example 1 except that the above 7 solutions of the acrylic pressure-sensitive adhesive were 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 thickness of the pressure-sensitive adhesive layer was 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 thickness of the pressure-sensitive adhesive layer was 5 μm.

<Comparative example 3>
[Preparation of surface protection film]
A surface protective film was prepared in the same manner as in Example 5 except that the thickness of the pressure-sensitive adhesive layer was 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 thickness of the pressure-sensitive adhesive layer was 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 thickness of the pressure-sensitive adhesive layer was 5 μm.

Tables 1 to 3 and the like show the above-mentioned compounding contents and the results of various measurements and evaluations for the surface protective films according to Examples and Comparative Examples.

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

The surface protective film disclosed herein is an optical member used during manufacturing, transportation, etc. of a thin optical member used as a component of a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, or the like. It is suitable as a surface protective film for protecting. In particular, a surface protective film (optical surface protective film) applied to thin optical members such as polarizing films, wave plates, retardation plates, optical compensation films, brightness improving films, light diffusing sheets, and reflective sheets for liquid crystal display panels. ) Is useful.

1 Surface protective film 2, 50 Polarizing film 12 Base film 20 Adhesive layer 20A Adhesive surface 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 Base material

Claims (5)

In a base film and a surface protective film for an optical member for a display panel in which an adhesive layer is formed on at least one side of the base film.
The pressure-sensitive adhesive layer contains at least one selected from the group consisting of an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive.
The thickness of the pressure-sensitive adhesive layer is less than 2 μm.
The optical member is selected from the group consisting of a polarizing film, a wavelength plate, a retardation plate, an optical compensation film, a reflective sheet, a brightness improving film, a cover glass, a cover sheet, a hard coat film, a transparent conductive glass, and a transparent conductive film. A surface protective film for an optical member for a display panel, which is characterized in that it is at least one kind. The surface protective film for an optical member for a display panel according to claim 1, wherein a 90 ° peel trigger peeling force at 50% RH at 23 ° C. with respect to the triacetyl cellulose film is 1 N / 50 mm or less. The surface protective film for an optical member for a display panel according to claim 1 or 2, wherein the base film has a thickness of 20 μm or more. An optical member that is protected by the surface protective film for an optical member for a display panel according to any one of claims 1 to 3. The optical member is a polarizing film containing a polarizer, and the optical member is a polarizing film.
The optical member according to claim 4, wherein the thickness of the polarizer is 8 μm or less.

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