JP2018123221A - Surface protective film and optical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface protective film that can be easily removed from a thin optical member or a display panel when the surface protective film is no more required, by utilizing the surface protective film to use an adhesive layer having a specific thickness, and an optical member protected by the surface protective film.SOLUTION: The surface protective film comprises a base film and an adhesive layer formed on at least one surface of the base film, in which the adhesive layer has a thickness of less than 2 μm. The surface protective film has a peeling force of 1 N/50 mm or less at the initiation of peeling from a triacetyl cellulose film at 23°C and 50% RH. The base film has a thickness of 20 μm or more; and the adhesive layer comprises at least one adhesive selected from an acrylic adhesive, a urethane-based adhesive and a silicone-based adhesive.SELECTED DRAWING: None

Description

  The present invention relates to a surface protective film and an optical member. In particular, polarizing films, wave plates, retardation plates, optical compensation films, reflection sheets, brightness enhancement films, cover glasses, cover sheets, hard coat films, transparent conductive glass, 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 a liquid crystal display, an organic EL display, and a touch panel display have been reduced in thickness from the viewpoint of design and portability, and there is a demand for reduction in thickness of optical members used in the display.

  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 is once formed into a roll form and then unwound from the roll and bonded to the liquid crystal cell. It is formed by cutting into a desired size according to the shape, and then bonding to a liquid crystal cell. Moreover, the surface protection film is bonded together for the said polarizing film in order to prevent the damage | wound and dirt which arise at the time of conveyance (patent document 1).

  The surface protection film is peeled off when it is no longer needed, but if the liquid crystal display panel is thin, the liquid crystal display will bend well when peeling off the surface protection film with a heavy peeling force. When the surface protective film cannot be peeled off or when it is peeled off, the liquid crystal display panel or the polarizing film may be broken.

JP 2001-305346 A

  Therefore, the present invention has been intensively studied in view of the above circumstances, and as a result, by using a surface protective film using a pressure-sensitive adhesive layer having a specific thickness, a surface protective film is unnecessary for thin optical members and display panels. 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 an adhesive layer is formed on at least one side of the base film, and the thickness of the 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 peel 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 base film preferably has a thickness of 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 pressure-sensitive adhesive, and a silicone 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 including a polarizer, and the thickness of the polarizer is 8 μm or less.

  The present invention uses a surface protective film having an adhesive layer having a specific thickness, and can be easily peeled off when the surface protective film is no longer necessary after being attached to a thin optical member or display panel. Is useful.

It is typical sectional drawing which shows one structural example which affixed the surface protection film which concerns on this invention to the polarizing film. It is explanatory drawing which shows the measuring method of 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 a form called 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 wave plate) It is suitable as a surface protective film that protects the surface of an optical member during processing or transport 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 spot or stripe. It may be an adhesive layer. In addition, the surface protective film disclosed herein may be in the form of a roll or a single sheet.

  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 sticking the pressure-sensitive adhesive layer 20 to an adherend (the surface of a transparent protective film 30 that 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) is a separator in which the surface of the pressure-sensitive adhesive layer 20 (sticking surface to the adherend) is a release surface at least on the pressure-sensitive adhesive layer 20 side. It may be in a form protected by (release liner). Or the form by which the adhesive layer 20 contact | abutted to the back surface of the base film 12 and the surface was protected by winding the surface protection film 1 in roll shape may be sufficient.

  Moreover, as shown in FIG. 1, it can stick to the surface of the transparent protective film 30 which comprises the polarizing film 2 via the adhesive layer 20 which comprises the surface protective film 1, and can protect the polarizing film 2. . The transparent protective film 30 and the polarizer 40 can form a polarizing film through the adhesive layer 22. Further, a 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 an adhesive layer 23, and the first adhesive layer 21 is further attached. It is also possible to laminate other optical members and the like through this.

<Base film of surface protective film>
The surface protective film of the present invention has a base film. In the technology disclosed herein, the resin material constituting the base film can be used without any particular limitation. For example, transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property, It is preferable to use a material excellent in 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 up into a roll shape, which is useful.

  Examples of the substrate film (substrate, support) include polyester polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate; cellulose polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonate A plastic film composed of a resin material having a main resin component (a main component of the resin component, typically a component occupying 50% by mass or more) such as an acrylic polymer such as polymethyl methacrylate; It can be preferably used as the substrate film. Other examples of the resin material include styrene polymers such as polystyrene and acrylonitrile-styrene copolymers; olefin polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers; Examples of the resin material include vinyl chloride polymers; amide polymers such as nylon 6, nylon 6,6, and aromatic polyamide. Still other examples of the resin material include imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers. , Arylate polymers, polyoxymethylene polymers, epoxy polymers and the like. A base film made of a blend of two or more of the above-described polymers may be used.

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

  Various additives such as an antistatic agent, an antioxidant, an ultraviolet absorber, a plasticizer, and a colorant (pigment, dye, etc.) are blended in the resin material constituting the base film as necessary. Also good. For example, a known or conventional surface treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and application of a primer may be performed. Such surface treatment can be, for example, a treatment for improving the adhesion between the base film and the pressure-sensitive adhesive layer (the anchoring property of the pressure-sensitive adhesive layer).

  In the surface protective film of the present invention, a plastic film subjected to antistatic treatment can be used as the substrate film. Use of the base film is preferable because charging of the surface protective film itself when peeled can be suppressed. In addition, the base film is a plastic film, and an antistatic treatment is performed on the plastic film, so that the surface protection film itself can be reduced in charge and can have an excellent antistatic ability on the adherend. In addition, there is no restriction | limiting in particular as a method to provide an antistatic function, A conventionally well-known method can be used, for example, antistatic resin which consists of an antistatic agent and a resin component, a conductive polymer, and a conductive substance. Examples thereof include a method of applying a conductive resin, a method of depositing or plating a conductive material, a method of kneading an antistatic agent, and the like.

  As thickness of the said base film, 20 micrometers or more are preferable, More preferably, it is 20-200 micrometers, More preferably, it is 25-150 micrometers, Especially preferably, it is 30-100 micrometers, Most preferably, it is 50-80 micrometers. 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 favorable, which is preferable. In particular, when used for a thin optical member having a thickness of 100 μm or less, a substrate film having a thickness of 50 μm or more is preferably used in order to ensure transportability and bonding workability.

  The surface protective film disclosed herein can be implemented in an embodiment including other layers in addition to the base film and the pressure-sensitive adhesive layer. Examples of the other layer include an undercoat layer (anchor layer) that improves the anchoring property of the antistatic layer and the pressure-sensitive adhesive layer.

<Adhesive layer of surface protective film>
The surface protective film of the present invention has an adhesive layer on at least one surface of the base film, and the adhesive layer is formed from an adhesive composition. Can be used without particular limitation. Examples of the pressure-sensitive adhesive composition include acrylic pressure-sensitive adhesive, urethane pressure-sensitive adhesive, synthetic rubber-based pressure-sensitive adhesive, natural rubber-based pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, polyester-based pressure-sensitive adhesive, and polyether-based pressure-sensitive adhesive. Among them, more preferably, it is 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, and particularly preferably a pressure-sensitive adhesive polymer. This is to use (contain) an acrylic pressure-sensitive adhesive using a (meth) acrylic polymer.

<Acrylic adhesive>
When the pressure-sensitive adhesive layer uses an acrylic pressure-sensitive adhesive, a (meth) acrylic polymer that is a pressure-sensitive polymer constituting the acrylic pressure-sensitive adhesive is an alkyl having 1 to 14 carbon atoms as a raw material monomer constituting the same. A (meth) acrylic monomer having a group can be used as the main 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 becomes easy to control the peeling force (adhesive strength) to the adherend (protected body) to be low and light peeling. A surface protective film excellent in removability and removability can be obtained. In the present invention, the (meth) acrylic polymer refers to an acrylic polymer and / or a methacrylic polymer, and the (meth) acrylate refers to 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, 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. It is done.

  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-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate Suitable examples include (meth) acrylic monomers having an alkyl group having 4 to 14 carbon atoms. In particular, by using a (meth) acrylic monomer having an alkyl group having 6 to 14 carbon atoms, it becomes easy to control the peel strength (adhesive strength) to the adherend low and has excellent removability. It becomes.

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

  In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer preferably contains a hydroxyl group-containing (meth) acrylic monomer as a raw material monomer. 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 the crosslinking of the pressure-sensitive adhesive composition, and as a result, balance between improvement of wettability by flow and reduction of peeling force (adhesive strength) in peeling. 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 because light release at high speed peeling is easy.

  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 monomer components constituting the (meth) acrylic polymer. More preferably, it is 0.1-15 mass%, Most preferably, it is 1-10 mass%. Within the above range, the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the resulting pressure-sensitive adhesive layer can be easily controlled, which is preferable.

  In addition, as another polymerizable monomer component, the Tg is 0 ° C. or lower (usually −100 ° C. or higher) for the reason that it is easy to balance the adhesive performance, and the glass transition temperature or peeling of the (meth) acrylic polymer. A polymerizable monomer or the like for adjusting the property can be used as long as the effects of the present invention are not impaired.

  As the polymerizable monomer other than the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms used in the (meth) acrylic polymer, and the hydroxyl group-containing (meth) acrylic monomer, A carboxyl group-containing (meth) acrylic monomer can be used. By using the carboxyl group-containing (meth) acrylic monomer, the surface protective film (adhesive layer) can suppress an increase in adhesive force over time, re-peelability, adhesive force increase prevention, and work In addition, it is excellent in shearing force as well as cohesive force of the pressure-sensitive adhesive layer, which is preferable.

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

  The carboxyl group-containing (meth) acrylic monomer is preferably 10% by mass or less, based on 100% by mass of the total amount of monomer components constituting the (meth) acrylic polymer, and is 0.005 to 10% by mass. More preferably, it is more preferably 0.01 to 8% by mass, and most preferably 0.01 to 5% by mass. Within the above range, the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the resulting pressure-sensitive adhesive layer can be easily controlled, which is preferable.

  Furthermore, the (meth) acrylic monomer having a C1-C14 alkyl group used in the (meth) acrylic polymer, a hydroxyl group-containing (meth) acrylic monomer, and a carboxyl group-containing (meth) acrylic Any other polymerizable monomer other than the monomer can be used without particular limitation as long as it does not impair the characteristics of the present invention. For example, cohesive strength / heat resistance improving components such as cyano group-containing monomers, vinyl ester monomers, aromatic vinyl monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, N-acryloylmorpholine In addition, a component having a functional group that functions as a crosslinking base point, such as a vinyl ether monomer, can be appropriately used. Among these, it is preferable to use nitrogen-containing monomers such as cyano group-containing monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, and N-acryloylmorpholine. By using a nitrogen-containing monomer, a surface protective film having further excellent shearing force can be obtained, which is useful. These polymerizable monomers can be used alone or in combination of two or more.

  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-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethyl. Examples include methacrylamide, N, N′-methylenebisacrylamide, N, N-dimethylaminopropyl acrylamide, 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, N, N-dimethylaminopropyl (meth) acrylate, and the like.

  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, chloromethyl styrene, α-methyl styrene, and other substituted styrene.

  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, the polymerizable monomer other than the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, the hydroxyl group-containing (meth) acrylic monomer, the carboxyl group-containing (meth) acrylic monomer, It is preferably 0 to 50% by mass and more preferably 0 to 20% by mass with respect to 100% by mass of the total amount of monomer components constituting the (meth) acrylic polymer. The other polymerizable monomers can be appropriately adjusted in order to obtain desired characteristics.

  The (meth) acrylic polymer may further contain an alkylene oxide group-containing reactive monomer as a monomer component. By using the monomer, it is 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. It is. When the weight average molecular weight is smaller than 100,000, the adhesive force tends to be generated due to the reduced cohesive force of the pressure-sensitive adhesive layer. On the other hand, when the weight average molecular weight exceeds 3 million, the fluidity of the polymer is lowered, the wetting to the adherend (for example, a polarizing film) becomes insufficient, and the adherend and the pressure-sensitive adhesive layer of the surface protective film It tends to cause blisters that occur during the period. In addition, a weight average molecular weight means what was 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 is difficult to flow, for example, the wettability to the polarizing film is insufficient, and the tendency 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, an adhesive layer excellent in wettability to the polarizing film and light releasability is easily obtained. In addition, the glass transition temperature of a (meth) acrylic-type polymer can be adjusted in the said range by changing the monomer component and composition ratio to be used suitably.

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

<Urethane adhesive>
When using a urethane-type adhesive for the said adhesive layer, arbitrary appropriate urethane-type adhesives can be employ | adopted. As such a urethane type adhesive, Preferably, what consists of a urethane type polymer which is an adhesive polymer obtained by making a polyol and a polyisocyanate compound react is mentioned. Examples of the polyol include polyether polyol, polyester polyol, polycarbonate polyol, and polycaprolactone polyol. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and the like.

<Silicon adhesive>
When using a silicone type adhesive for the said adhesive layer, arbitrary appropriate silicone type adhesives can be employ | adopted. As such a silicone-based pressure-sensitive adhesive, one obtained by blending or agglomerating a silicone-based polymer that is a pressure-sensitive polymer can be preferably used.

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

  As the curing reaction of the addition reaction curable silicone pressure-sensitive adhesive, for example, when obtaining a polyalkyl silicone pressure-sensitive adhesive, generally, a method of curing a polyalkylhydrogensiloxane composition with a platinum catalyst can be mentioned.

<Crosslinking agent>
In the surface protective film of the present invention, the pressure-sensitive adhesive composition preferably contains a crosslinking agent. Moreover, in this invention, it can be set as an adhesive layer using the said adhesive composition. For example, in the case where the pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive containing the (meth) acrylic polymer, the constitutional unit, the structural ratio, the selection and addition ratio of the cross-linking agent, etc. are appropriately determined. By adjusting and crosslinking, a surface protective film (pressure-sensitive adhesive layer) having more excellent heat resistance can be obtained.

  As the crosslinking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine derivative, a metal chelate compound, or the like may be used. In particular, the use of an isocyanate compound is a preferred embodiment. Moreover, these compounds may be used independently and may be used in mixture of 2 or more types.

  Examples of the isocyanate compounds include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI), dimer acid 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 compound Allophanate bond, biuret bond, isocyanurate bond, uretdione bond, urea bond, carbodiimide bond, Reton'imin bond, polyisocynate modified products thereof obtained by modifying the like oxadiazinetrione bond. For example, as commercial products, the product names Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (above, manufactured by Mitsui Chemicals), Sumijoule T80, Sumijoule L, Death Module N3400 (above, Sumika Bayer Urethane Co., Ltd.) 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 may be used in combination of two or more, and 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 becomes possible to achieve both tackiness and resilience resistance (adhesiveness to a curved surface), and a surface protective film with better 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 Company) and 1,3-bis (N, N-dioxy). Glycidylaminomethyl) cyclohexane (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.).

  Examples of the melamine resin include hexamethylol melamine. Examples of the aziridine derivative include commercially available product names HDU, TAZM, TAZO (manufactured by Mutual Yakugyo Co., Ltd.) and the like.

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

  The content of the crosslinking 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 0.5-10 mass parts, More preferably, it is 1-6 mass parts. When the content is less than 0.01 parts by mass, the crosslinking formation by the crosslinking agent becomes insufficient, the cohesive force of the resulting pressure-sensitive adhesive layer becomes small, and sufficient heat resistance may not be obtained, It tends to cause glue 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) becomes insufficient, and the adherend and the pressure-sensitive adhesive. There is a tendency to cause blisters generated between the layer (adhesive composition layer). These crosslinking 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 causing any of the above-described cross-linking reactions to proceed more effectively. Examples of such crosslinking catalysts include tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris (acetylacetonato) iron (iron (III) acetylacetonate), 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 (tridecan-6,8-dionato) iron, Lis (1-phenylbutane-1,3-dionato) iron, tris (hexafluoroacetylacetonato) iron, tris (ethyl acetoacetate) iron, tris (acetoacetate-n-propyl) iron, tris (isopropyl acetoacetate) Iron, tris (acetoacetate-n-butyl) iron, tris (acetoacetate-sec-butyl) iron, tris (acetoacetate-tert-butyl) iron, tris (methyl propionylacetate), tris (ethyl propionylacetate) iron , Tris (propionyl acetate-n-propyl) iron, tris (propionyl acetate isopropyl) iron, tris (propionyl acetate-n-butyl) iron, tris (propionyl acetate-sec-butyl) iron, tris (propionyl acetate-tert-butyl) ) Iron, Tris (benzyl acetoacetate) iron, Tris (dimethyl malonate) iron, Tris (malo) Iron-based catalysts such as diethyl acid) iron, trimethoxy iron, 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 with respect to 100 parts by mass of the (meth) acrylic polymer, for example, 0.001 to 0.5 Part by mass is more preferable. Within the above range, when the pressure-sensitive adhesive layer is formed, the speed of the cross-linking reaction is high, and the pot life of the pressure-sensitive adhesive composition is lengthened.

  Further, the pressure-sensitive adhesive composition may contain an alkylene oxide (AO) group-containing compound. This makes it possible to improve the wettability to the adherend, to improve the adherence to the adherend, and to easily suppress the mixing of bubbles and the like generated during the sticking. .

  Specific examples of the alkylene oxide (AO) group-containing compound include, for example, polyoxyalkylene alkylamine, polyoxyalkylene diamine, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene alkyl phenyl ether, polyoxy Nonionic surfactants such as alkylene alkyl ether, polyoxyalkylene allyl 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 allyl ether sulfate salt, polyoxyalkyl Anionic surfactants such as alkyl ether phosphate salts, polyoxyalkylene alkyl phenyl ether sulfate salts, polyoxyalkylene alkyl allyl phenyl ether sulfate salts, polyoxyalkylene alkyl phenyl ether phosphate salts; Cationic surfactants and amphoteric surfactants having an oxyalkylene chain (polyalkylene oxide chain), polyether compounds having a polyoxyalkylene chain (and derivatives thereof), ester compounds having a polyoxyalkylene chain ( And acrylic compounds having a polyoxyalkylene chain (and derivatives thereof) and the like. Moreover, you may mix | blend a polyoxyalkylene chain containing monomer with an acrylic polymer as a polyoxyalkylene chain containing compound. Such polyoxyalkylene chain-containing compounds 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. A copolymer etc. are mentioned. Examples of the derivative of the ether compound having a polyoxyalkylene chain include an oxypropylene group-containing compound whose end is etherified (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.), an oxypropylene group containing an acetylated end Compound (terminal acetylated PPG etc.), etc. are mentioned.
In addition, specific examples of the ester compound having a polyoxyalkylene chain include an ester compound having an oxyalkylene group. As said oxyalkylene group, 1-50 are preferable from a viewpoint that an ionic compound coordinates, and 2-30 are more preferable, and 2-20 are more preferable for the addition 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.
Specific examples of the acrylic compound having a polyoxyalkylene chain include a (meth) acrylate polymer having an oxyalkylene group. As said oxyalkylene group, 1-50 are preferable from a viewpoint that an ionic compound coordinates, and 2-30 are more preferable, and 2-20 are more preferable for the addition mole number of an oxyalkylene unit. The terminal of the oxyalkylene chain may be 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) acrylic acid alkylene oxide as a monomer unit (component). As a specific example of the (meth) acrylic acid alkylene oxide, As the ethylene glycol group-containing (meth) acrylate, for example, methoxy-polyethylene glycol (meth) acrylate type such as methoxy-diethylene glycol (meth) acrylate and methoxy-triethylene glycol (meth) acrylate, ethoxy-diethylene glycol (meth) Acrylate, ethoxy-polyethylene glycol (meth) acrylate type such as ethoxy-triethylene glycol (meth) acrylate, butoxy-diethylene glycol (meth) acrylate, Butoxy-polyethylene glycol (meth) acrylate type such as toxi-triethylene glycol (meth) acrylate, phenoxy-polyethylene glycol (meth) acrylate type such as phenoxy-diethylene glycol (meth) acrylate, phenoxy-triethylene glycol (meth) acrylate, Examples include methoxy-polypropylene glycol (meth) acrylate type such as 2-ethylhexyl-polyethylene glycol (meth) acrylate, nonylphenol-polyethylene glycol (meth) acrylate type, and methoxy-dipropylene glycol (meth) acrylate.

  Moreover, as said monomer unit (component), other monomer units (component) other than the said (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, 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) ) Acrylates, isodecyl (meth) acrylates, n-dodecyl (meth) acrylates, n-tridecyl (meth) acrylates, n-tetradecyl (meth) acrylates and other acrylates and / or methacrylates having 1 to 14 carbon atoms And the like.

  Furthermore, as other monomer units (components) other than the (meth) acrylic acid alkylene oxide, carboxyl group-containing (meth) acrylate, phosphoric acid group-containing (meth) acrylate, cyano group-containing (meth) acrylate, vinyl esters, aromatic 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 can also be used as appropriate.

  The number average molecular weight (Mn) of the alkylene oxide (AO) group-containing compound is suitably 50000 or less, preferably 200 to 30000, more preferably 200 to 10000, and usually 200 to 5000. Are preferably used. When Mn is larger than 50000, 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 with the polyoxyalkylene compound may easily occur. In addition, Mn means the value of polystyrene conversion obtained by gel permeation chromatography (GPC) here.

  The content of the alkylene oxide (AO) group-containing compound is not particularly limited, but can be, for example, about 0.005 to 20 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. 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 wettability effect on the adherend is reduced. If the blending amount is too large, contamination with the polyoxyalkylene compound is likely to occur, and the 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 lubrication. Agent, leveling agent, antioxidant, corrosion inhibitor, light stabilizer, UV absorber, polymerization inhibitor, silane coupling agent, antistatic agent, crosslinking retarder, inorganic or organic filler, metal powder, particle It can be added as appropriate depending on the application in which the shape, foil or the like is used.

<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 surface of the base film. In this case, the pressure-sensitive adhesive composition is crosslinked after the pressure-sensitive adhesive composition is applied. In general, after forming a pressure-sensitive adhesive layer comprising a crosslinked pressure-sensitive adhesive composition on a separator provided with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent layer, It is also possible to transfer to a film or the like.

  The method for forming the pressure-sensitive adhesive layer on the base film is not particularly limited. For example, the pressure-sensitive adhesive layer is formed by applying the pressure-sensitive adhesive composition (solution) to the base film and removing the polymerization solvent by drying. It is produced by forming on a base film. Thereafter, curing may be performed for the purpose of adjusting the component transfer of the pressure-sensitive adhesive layer or adjusting the crosslinking reaction. Moreover, when producing a surface protective film by applying the pressure-sensitive adhesive composition on the base film, at least one kind other than the polymerization solvent is included in the pressure-sensitive adhesive composition so that it can be uniformly applied onto the base film. A new solvent may be added.

  Moreover, as a formation method of the adhesive layer at the time of manufacturing the surface protection film of this invention, the well-known method used for manufacture of adhesive tapes is used. Specific examples include roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, extrusion coating using a die coater, and the like.

  In the surface protective film of the present invention, the pressure-sensitive adhesive layer has a thickness of 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 0.00. The thickness is 4 to 1.2 μm, and particularly preferably 0.5 to 1 μm. If the thickness of the pressure-sensitive adhesive layer is within the above range, the peel-off force will be low, and it can be easily peeled off when a surface protective film is no longer needed after being attached to a thin optical member or display panel. ,preferable.

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 Pa, more preferably 1.0 × 10 ⁵ to a 5.0 × ¹⁰ 6 Pa, more preferably from ^{3.0 × 10 5 ~5.0 × 10 6} Pa. By adjusting within the above range, the trigger peel force can be kept low, the adhesion to the surface of the adherend can be secured, and the bonding can be easily performed, which is a preferred embodiment.

  Further, the 90 ° peel trigger peeling force at 23 ° C. and 50% RH with respect to the triacetyl cellulose film (polarizing film) of the surface protective film (adhesive layer thereof) 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. When the trigger peeling force exceeds 1 N / 50 mm, peeling resistance is applied when the surface protective film is peeled from the polarizing film with a pickup tape, and peeling is difficult.

  The surface protective film of the present invention preferably has a total thickness of 20 to 400 μm, more preferably 30 to 200 μm, still more preferably 40 to 150 μm, and particularly preferably 50 to 100 μm. . Within the above range, the adhesive properties (removability, adhesiveness, etc.), workability, and appearance properties are excellent and a preferred embodiment is obtained. In addition, the said total thickness means the sum total of the thickness containing all the layers, when a base film, an adhesive layer, and another layer exist.

<Separator>
In the surface protective film of the present invention, a separator can be bonded 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 necessary.

  Examples of the material constituting the separator include paper and plastic film, and a 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. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer 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 5 to 200 μm, preferably about 10 to 100 μm. It is preferable for it to be in the above-mentioned range since it is excellent in workability for bonding to the pressure-sensitive adhesive layer and workability for peeling from the pressure-sensitive adhesive layer. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, 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 said surface protection film can be used for surface protection uses, such as processing, conveyance, and the time of shipment, and becomes useful in order to protect the surface of the said optical member (polarizing film etc.). In particular, it is very useful for thin optical members (such as polarizing films) and display panels because they can be easily peeled off when the surface protective film is no longer needed.

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

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

<Polarizer>
As the polarizer, one using a polyvinyl alcohol resin is used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable.

  A polarizer obtained by dyeing the polyvinyl alcohol film with iodine and uniaxially stretching it can be prepared by, for example, dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. . If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film 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 even more 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, and more preferably 3 μm or more. Such a thin polarizer has less thickness unevenness, excellent visibility, and less dimensional change, and therefore excellent durability against thermal shock. As a thin polarizer, typically, Japanese Patent No. 4751486, Japanese Patent No. 4751481, Japanese Patent No. 4815544, Japanese Patent No. 5048120, International Publication No. 2014/0777599, International Publication No. The thin polarizer described in the publication 2014/077636 pamphlet etc. or the thin polarizer obtained from the manufacturing method described in these can be mentioned.

The polarizer has an optical property represented by the following formula: P> − (100.929T-42.4-1) × 100 (where T <42.3), or , P ≧ 99.9 (however, T ≧ 42.3) is preferably satisfied. A polarizer configured so as to satisfy the above-described conditions uniquely has performance required as a display for a liquid crystal television 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 other uses, for example, it is bonded to the viewing side of the organic EL cell.

  As the thin polarizer, among the production methods including the step of stretching in the state of a laminate and the step of dyeing, Patent No. 4751486, Patent, in that it can be stretched at a high magnification and the polarization performance can be improved. What is obtained by the manufacturing method including the process of extending | stretching in a boric-acid aqueous solution as described in the 4751481 specification and the patent 4815544 specification is preferable, and it describes especially in the patent 4751481 specification and the patent 4815544 specification. What is obtained by the manufacturing method including the process of extending | stretching in the air auxiliary before extending | stretching in the boric-acid aqueous solution which has this is preferable. These thin polarizers can be obtained by a production method including a step of stretching and dyeing a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin base film in the state of a laminate. If it is this manufacturing method, even if a PVA-type resin layer is thin, it will be possible to extend | stretch without troubles, such as a fracture | rupture by extending | stretching, by being supported by the resin base film for extending | stretching.

(Transparent protective film)
The material constituting the transparent protective film is not particularly limited, but a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. 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, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) And polymers based on polycarbonate and polycarbonate. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Examples of the polymer that forms the transparent protective film include polymer blends. These transparent protective films are usually bonded to the polarizer by an adhesive layer. In addition, 1 or more types of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent.

  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. is there. When content of the said thermoplastic resin in a transparent protective film is 50 mass% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  The thickness of the transparent protective film can be determined as appropriate, but in general, it is preferably 5 to 50 μm, more preferably 5 to 45 μm from the viewpoints of workability such as strength and handleability, and thin layer properties. Is preferred.

  A functional layer such as a hard coat layer, an antireflection layer, an antisticking layer, a diffusion layer or an antiglare 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, antireflection layer, antisticking layer, diffusion layer and antiglare layer can be provided on the transparent protective film itself, and separately provided separately from the transparent protective film. You can also.

  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 the both are laminated without an air gap by an intervening layer.

  The adhesive layer is formed of an adhesive. The type of the adhesive is not particularly limited, and various types can be used. The adhesive layer is not particularly limited as long as it is optically transparent. Examples of the adhesive include water-based, solvent-based, hot-melt-based, active energy ray-curable types, and the like. Or an active energy ray hardening-type adhesive agent is suitable.

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

  The active energy ray curable adhesive is an adhesive that cures by an active energy ray such as an electron beam or ultraviolet rays (radical curable type, cationic curable type), for example, an electron beam curable type or an ultraviolet curable type. Can be used. As the active energy ray curable adhesive, for example, a photo radical curable adhesive can be used. When the photo radical curable active energy ray curable adhesive is used as an ultraviolet curable adhesive, the adhesive contains a radical polymerizable compound and a photo polymerization initiator.

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

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

  In addition, in laminating | stacking a polarizer and a transparent protective film, an easily bonding layer can be provided between a transparent protective film and an adhesive bond 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, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like. These polymer resins can be used alone or in combination of two or more. Moreover, you may add another additive for formation of an easily bonding layer. Specifically, a stabilizer such as a tackifier, an ultraviolet absorber, an antioxidant, and a heat resistance stabilizer may be used.

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

  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 the material exhibits a certain degree of strong adhesion to both the base film and the polyvinyl alcohol-based resin layer. For example, a thermoplastic resin excellent in transparency, thermal stability, stretchability, etc. is used. Examples of the thermoplastic resin include an acrylic resin, a polyolefin resin, a polyester resin, a polyvinyl alcohol resin, or a mixture thereof.

<First adhesive layer>
The polarizing film may have a structure in which a first pressure-sensitive adhesive layer is laminated on at least one surface of the polarizing film, and other optical members may be disposed 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.) etc. 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. Adhesives include rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, Examples thereof include cellulose-based pressure-sensitive adhesives. Among these pressure-sensitive adhesives, those having excellent optical transparency, suitable wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and excellent weather resistance and heat resistance are preferably used. An acrylic pressure-sensitive adhesive is preferably used as one exhibiting such characteristics.

  As a method for forming the first pressure-sensitive adhesive layer, for example, a method in which the pressure-sensitive adhesive is applied to a release-treated separator, a polymerization solvent is dried and removed to form a pressure-sensitive adhesive layer, and then transferred to a polarizing film, or The pressure-sensitive adhesive is prepared by a method of applying the pressure-sensitive adhesive to a polarizing film, drying and removing the polymerization solvent, and forming a pressure-sensitive adhesive layer on the polarizer. In applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be added as appropriate. A silicone separator is preferably used as the release-treated separator.

  In the step of forming the pressure-sensitive adhesive layer by applying and drying the pressure-sensitive adhesive of the present invention on such a separator, an appropriate method can be appropriately employed depending on the purpose. Preferably, a method of heating 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 within the above range, an adhesive having excellent adhesive properties can be obtained.

  Various methods are used as a method of 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 thereof include an extrusion coating method.

  What is the thickness of the first pressure-sensitive adhesive layer? Preferably, it is 2-50 micrometers, More preferably, it is 2-40 micrometers, More preferably, it is 5-35 micrometers.

  The separator can protect the adhesive surface of the first adhesive layer until it is practically used. Examples of the constituent material of the separator include, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. Although an appropriate thin leaf body etc. can be mentioned, a plastic film is used suitably from the point which is excellent in surface smoothness. The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. 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-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, the release property from the first pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment on the surface of the release film.

  As for the thickness of the said separator, 5-50 micrometers is preferable normally, More preferably, it is 20-40 micrometers.

  Hereinafter, several examples related to the present invention will be described, but the present invention is not intended to be limited to those shown in the specific examples. In the following description, “part” and “%” are based on mass unless otherwise specified. Further, the blending amount (addition amount) in the table is shown.

  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-8220GPC) 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 rate: 0.6 ml / min
Measurement temperature: 40 ° C
column:
Sample column; TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column; TSKgel SuperH-RC (1)
Detector: Differential refractometer (RI)
The weight average molecular weight was determined in terms of polystyrene.

<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 of each monomer.
Formula: 1 / (Tg + 273) = Σ [Wn / (Tgn + 273)]
[Wherein, 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 of each monomer, and n is the type of each monomer Represents. ]
Literature values:
2-ethylhexyl acrylate (2EHA): -70 ° C
Butyl acrylate (BA): -55 ° C
2-Hydroxyethyl acrylate (HEA): -15 ° C
Acrylic acid (AA): 106 ° C

  As reference values, “Synthesis / design of acrylic resin and development of new applications” (published by Central Management Development Center Publishing Department), “Polymer Handbook” (John Wiley & Sons), and monomer manufacturer maker's Kadalog values were referred to.

Moreover, about the glass transition temperature (Tg) (degreeC) of the (meth) acrylic-type polymer obtained with the monomer whose document value is unknown, it can determine by a dynamic viscoelasticity measurement in the following procedure.
First, a (meth) acrylic polymer sheet having a thickness of 20 μm is laminated to a thickness of about 2 mm, punched to φ7.9 mm, a cylindrical pellet is prepared, and a glass transition temperature (Tg) measurement sample is obtained. did.
Using the above measurement sample, the measurement sample is fixed to a jig having a φ7.9 mm parallel plate, and the temperature dependence of the loss elastic modulus G ″ is measured by a dynamic viscoelasticity measuring device (ARES, manufactured by Rheometrics). The temperature at which the obtained G ″ curve was maximized was measured as the glass transition temperature (Tg) (° C.). The measurement conditions are as follows.
Measurement: Shear mode Temperature range: -70 ° C to 150 ° C
Temperature increase range: 5 ° C / min
Frequency: 1Hz

<Storage elastic modulus (G ')>
A sheet of an adhesive layer having a thickness of 20 μm was laminated to a thickness of about 2 mm, and this was punched out to φ7.9 mm to produce a cylindrical pellet to obtain a storage elastic modulus measurement sample.
The above measurement sample is fixed to a jig of 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 apparatus (ARES, manufactured by Rheometrics). did. In addition, the measurement of the storage elastic modulus was implemented about what used the acrylic 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.

<Trigger peeling force (pickup force)>
As shown in FIG. 2, the surface protective film 1 according to each example is cut to a size of 50 mm in width and 100 mm in length, and the pressure-sensitive adhesive surface 20 </ b> A of the surface protective film 1 is applied to the following piece protective polarizing film 50 with a pressure of 0.25 MPa. And crimping at a speed of 0.3 m / min. A single-sided adhesive tape (manufactured by Nichiban Co., Ltd., trade name “Cello 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 pressure-bonded with a hand roller onto the center of the back surface of the surface protective film 1 having a width of 50 mm so that the end portion protruded 30 mm. This was left under conditions of 23 ° C. and 50% RH for 10 seconds. Thereafter, the maximum stress applied at the beginning of peeling when the single-sided adhesive tape 60 was peeled off at a speed of 0.3 m / min in the 90 ° direction by an autograph was used as a peeling force (N / 50 mm).

<Preparation of polarizing film>
(Production of polarizer)
One side of an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a water absorption of 0.75% and Tg of 75 ° C. is subjected to corona treatment. Alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl modification degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. An aqueous solution containing 9: 1 ratio of the trade name “Gosefimer Z200”) was applied and dried at 25 ° C. to form a PVA-based resin layer having a thickness of 11 μm, thereby preparing a laminate.
The obtained laminate was uniaxially stretched in the longitudinal direction (longitudinal direction) 2.0 times between rolls having different peripheral speeds in an oven at 120 ° C. (air-assisted stretching process).
Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 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 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 immersed in an iodine aqueous solution obtained by mixing 1.0 part by mass of potassium iodide (dyeing treatment). .
Subsequently, it was immersed for 30 seconds in a crosslinking bath having a liquid temperature of 30 ° C. (a boric acid aqueous 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). (Crosslinking treatment).
Thereafter, the laminate is immersed in an aqueous boric acid solution 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 in the longitudinal direction (longitudinal direction) so that the total stretching ratio was 5.5 times (in-water stretching treatment).
Thereafter, the laminate was immersed in a washing bath having 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). As a result, an optical film laminate including 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 acrylic acid, 0.1 part of 2-hydroxyethyl acrylate and 2,2′-azobisisobutyrate A solution was prepared by adding 0.3 parts of ronitrile with ethyl acetate. Next, 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. Furthermore, the acrylic polymer solution which added ethyl acetate to the solution containing this acrylic polymer and adjusted solid content concentration to 30% was obtained.
As a cross-linking agent, 100 parts by weight of the solid content of the acrylic polymer solution is a cross-linking agent mainly composed of a compound having an isocyanate group of 0.5 part (trade name “Coronate L” manufactured by Nippon Polyurethane Co., Ltd.). And 0.075 parts of γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KMB-403”) as a silane coupling agent in this order, Was prepared. The pressure-sensitive adhesive solution was applied to the surface of a release sheet (separator) made of a polyethylene terephthalate film (thickness 38 μm) subjected to a release treatment so that the thickness after drying was 25 μm and dried to form a pressure-sensitive adhesive layer. Formed.

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

<Preparation of acrylic polymer (1)>
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 95 parts by mass of 2-ethylhexyl acrylate (2EHA), 5 parts by mass of 2-hydroxyethyl acrylate (HEA), 2 as a polymerization initiator , 2'-azobisisobutyronitrile and 150 parts by mass of ethyl acetate were charged, nitrogen gas was introduced while gently stirring, and the temperature in the flask was kept at around 65 ° C for 6 hours of polymerization. Reaction was performed and the acrylic polymer (1) solution (40 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.

<Preparation of acrylic polymer (2)>
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 95 parts by mass of butyl acrylate (BA), 5 parts by mass of acrylic acid (AA), and 2,2′-azo as a polymerization initiator Charge 0.2 parts by mass of bisisobutyronitrile and 234 parts by mass of ethyl acetate, introduce nitrogen gas while gently stirring, perform the polymerization reaction for 7 hours while maintaining the liquid temperature in the flask at around 63 ° C. A 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% by mass) is diluted to 20% by mass with ethyl acetate, and trimethylo- which is a trifunctional isocyanate compound as a crosslinking agent is added to 500 parts by mass (100 parts by mass of solid content) of this solution. 2.7 parts by mass of rupropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, coronate L: C / L) (solid content 2 parts by mass), dibutyltin dilaurate (1% by mass ethyl acetate) as a crosslinking catalyst Solution) 3 parts by mass (solid content: 0.03 part by mass) was added and mixed and stirred to prepare an acrylic pressure-sensitive adhesive 1 solution.

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

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

<Example 1>
[Production of surface protective 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 pressure-sensitive adhesive layer. Next, the surface of the pressure-sensitive adhesive layer was bonded with a silicone-treated surface of a polyethylene terephthalate film (thickness 25 μm) that had been subjected to silicone treatment on one side to produce a surface protective film.

<Example 2>
[Production of surface protective 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>
[Production of surface protective film]
Except that the acrylic pressure-sensitive adhesive solution 2 was used to apply and form a pressure-sensitive adhesive layer having a thickness of 1.9 μm on one side of a 50 μm-thick polyester film (Toyobo, E5000) as a base film. A surface protective film was produced in the same manner as in Example 2.

<Example 4>
[Production of surface protective 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 0.5 μm-thick pressure-sensitive adhesive layer. Next, the surface of the pressure-sensitive adhesive layer was bonded with a silicone-treated surface of a polyethylene terephthalate film (thickness 25 μm) that had been subjected to silicone treatment on one side to produce a surface protective film.

<Examples 5-9>
In the same manner as in Example 4, the acrylic adhesive 3 solution was used to form adhesive layers having thicknesses (0.5 μm, 1 μm, 1.9 μm) shown in Table 3 with thicknesses (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 urethane 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, Sanniks GP3000 (manufactured by Sanyo Chemical Co., Ltd., Mn = 3000) 13 which is a polyol having three hydroxyl groups 2 parts by mass of Sannix GP1000 (Sanyo Kasei Co., Ltd., Mn = 1000) which is a polyol having three hydroxyl groups, 18 parts by mass of an isocyanate compound (Coronate HX: C / HX, manufactured by Tosoh Corporation) as a crosslinking agent, As a catalyst, 0.04 part by mass of iron (III) acetylacetonate (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.

[Production of surface protective film]
A surface protective film was produced by the same method and conditions as in Example 1 except that the urethane-based adhesive 4 solution was used.

<Example 11>
[Preparation of Silicone Adhesive 5 Solution]
As a silicone-based pressure-sensitive 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.). (Product) 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.

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

<Example 12>
[Preparation of acrylic adhesive 6 solution]
The 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 the solid content) of this solution. (Manufactured by ADEKA, polyoxyethylene-polyoxypropylene block polymer, trade name "Adekapluronic 25R-1") 0.5 parts by mass (solid content 0.5 parts by mass), a trifunctional isocyanate compound as a crosslinking agent Hexamethylene diisocyanate isocyanurate (Tosoh Corp., Coronate HX: C / HX) 4 parts by mass (solid content 4 parts by mass), dibutyltin dilaurate (1% by mass ethyl acetate solution) 3 parts by mass (solid content) 0.03 parts by mass) was added and mixed and stirred to prepare an acrylic pressure-sensitive adhesive 6 solution.

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

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

[Production of surface protective film]
A surface protective film was produced in the same manner as in Example 1 except that the above acrylic pressure-sensitive adhesive 7 solution was used.

<Comparative Example 1>
[Production of surface protective 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>
[Production of surface protective 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>
[Production of surface protective 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 2 μm.

<Comparative example 4>
[Production of surface protective 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>
[Production of surface protective 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.

  About the surface protection film which concerns on an Example and a comparative example, the result of having performed the mixing | blending content mentioned above, various measurements, and evaluation was shown in Table 1-3.

  From Table 3, in all Examples, since the thickness of the adhesive layer used the surface protection film below 2 micrometers, it has confirmed that a trigger peeling force could be restrained low. On the other hand, in all the comparative examples, when the thickness of the pressure-sensitive adhesive layer was 2 μm or more, it was confirmed that the trigger peeling force was increased.

  The surface protective film disclosed herein is used when 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 is manufactured or transported. It is suitable as a surface protective film for protecting the film. In particular, a surface protective film (optical surface protective film for optical use) applied to thin optical members such as polarizing films for liquid crystal display panels, wave plates, retardation plates, optical compensation films, brightness enhancement films, light diffusion sheets, and reflective sheets ) Is useful.

DESCRIPTION OF SYMBOLS 1 Surface protective film 2, 50 Polarizing film 12 Base film 20 Adhesive layer 20A Adhesive surface 21 1st 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 (6)

In the surface protective film in which the adhesive layer is formed on at least one side of the base film and the base film,
A surface protective film, wherein the pressure-sensitive adhesive layer has a thickness of less than 2 μm. The surface protective film according to claim 1, wherein a 90 ° peel trigger peeling force at 23 ° C. and 50% RH is 1 N / 50 mm or less. The thickness of the said base film is 20 micrometers or more, The surface protection film of Claim 1 or 2 characterized by the above-mentioned. The said adhesive layer contains at least 1 sort (s) selected from the group which consists of an acrylic adhesive, a urethane type adhesive, and a silicone type adhesive, The any one of Claims 1-3 characterized by the above-mentioned. Surface protection film. An optical member that is protected by the surface protective film according to claim 1. The optical member is a polarizing film containing a polarizer,
The optical member according to claim 5, wherein the polarizer has a thickness of 8 μm or less.