KR102158128B1 - Surface protective film for polarizing plate, polarizing plate and method for manufacturing polarizing plate - Google Patents

Abstract

[식 중, R 및 R'는 메틸기 또는 페닐기이며, R 및 R'는 동일하여도 좋고, 상이하여도 좋다. 또한, m은 0∼3000이고, n은 1∼3000이다.][Problem] The present invention makes it a subject to provide a surface protective film for polarizing plates that can reduce dynamic friction while increasing shearing force, and achieve both curl control and slipperiness.
[Solving means] The surface protective film for polarizing plates of the present invention is a surface protective film for polarizing plates having an adhesive layer formed of an adhesive composition on one or both sides of a support film, wherein the adhesive composition is a monomer component, at least, having 1 carbon number. A (meth)acrylic polymer containing 50 to 99.9% by mass of a (meth)acrylic monomer having an alkyl group of to 14, and a silicone compound represented by the following formula, with respect to 100 parts by mass of the (meth)acrylic polymer, The silicone compound was contained in an amount of 0.01 parts by mass to less than 1 part by mass, and 1 cm 2 of the adhesive area of the pressure-sensitive adhesive layer was bonded to a TAC polarizing plate, bonded at 23° C. for 30 minutes, and then stretched at a tensile speed of 0.06 mm/min in the shear direction. When the shear force is 15 N/cm 2 or more, the surface of the pressure-sensitive adhesive layer is bonded to a TAC polarizing plate, adhered at 23° C. for 30 minutes, and then the surface protective film for polarizing plate is peeled off from the TAC polarizing plate. Characterized in that the dynamic friction force when the luminance increasing film is brought into contact with the surface to which the pressure-sensitive adhesive surface has been adhered and a load of 200 g is applied and pulled in a direction parallel to the contact surface at a tensile speed of 100 mm/min is 1 N or less To:

[In the formula, R and R'are a methyl group or a phenyl group, and R and R'may be the same or different. In addition, m is 0 to 3000, and n is 1 to 3000.]

Description

Surface protective film for polarizing plate, polarizing plate, and manufacturing method of polarizing plate {SURFACE PROTECTIVE FILM FOR POLARIZING PLATE, POLARIZING PLATE AND METHOD FOR MANUFACTURING POLARIZING PLATE}

The present invention relates to a surface protective film for a polarizing plate, a polarizing plate protected by the surface protective film, and a method of manufacturing a polarizing plate. Specifically, it relates to a surface protective film for polarizing plates used to protect the surface of a polarizing plate by adhering to a polarizing plate used for a liquid crystal display. For example, the surface protective film for polarizing plates is used to protect polarizing plates in various processes, such as protection at the time of shipment of polarizing plates by polarizing plate manufacturers, and protection of polarizing plates during display device (liquid crystal module) manufacturing processes by liquid crystal display manufacturers. Used for In addition, the present invention relates to a polarizing plate protected by a surface protective film for a polarizing plate, and a method of manufacturing a silicon compound transfer type polarizing plate in which a silicon compound is transferred to the surface of the polarizing plate.

In transportation of optical components and electronic components or installation on a printed board, individual components are conveyed in a state in which they are packaged in a predetermined sheet or in a state in which an adhesive tape is adhered. Among them, surface protection films are particularly widely used in the field of optical and electronic components.

The surface protective film is generally bonded to an adherend through an adhesive applied to the support film side, and is used for the purpose of preventing scratches and contamination that occur during processing and transport of the adherend (Patent Document 1). For example, a liquid crystal display (LCD) panel is formed by bonding an optical member such as a polarizing plate or a wavelength plate to a liquid crystal cell through an adhesive. In optical members such as these polarizing plates, a surface protective film is bonded to each other through an adhesive, and is protected from scratches and contamination generated during processing and transportation.

Recently, as the polarizing plate used in the LCD panel is thinner, the polarizing plate is also thinned, and thus, the distance (interval) between the luminance raising film and the polarizing plate when assembling the LCD panel becomes narrower as the thickness decreases and becomes thinner. The resulting LCD panel or polarizing plate is bent, causing problems such as the luminance increasing film and the polarizing plate coming into contact with each other, causing a scratch on the polarizing plate.

In addition, unnecessary curls or unintended curls (curls refer to the phenomenon of bending, for example, a phenomenon in which a flat plate is bent toward one side, a phenomenon in which a flat plate is bent as if it is a wave) occurs in the polarizing plate itself. In order not to do so, curl adjustment is required. When unnecessary curls or unintended curls occur, handling properties are poor. For example, when a polarizing plate or the like is adhered to a liquid crystal cell, problems such as penetration of air bubbles may occur.

On the other hand, by blending polyether-modified silicone that serves as an antistatic agent in the pressure-sensitive adhesive layer of the surface protection film, the polyether-modified silicone is transferred to the surface of the adherend (eg, polarizing plate) in a small amount, thereby imparting antistatic properties to the adherend. In addition, in the case where the adherend and the member come into contact with each other, the dynamic friction force in the adherend can be reduced, and the sliding property can be improved, and it becomes possible to suppress the occurrence of wounds on the adherend. On the other hand, the presence of the polyether-modified silicone transferred in a small amount on the surface of the adherend causes a problem in that the shear force in the adherend decreases, resulting in inferior curl adjustability of the adherend.

Patent Document 1: Japanese Patent Application Laid-Open No. Hei 9-165460

Thus, the object of the present invention is to increase the shear force of the pressure-sensitive adhesive layer in order to solve the problems in the conventional surface protective film, and to increase the dynamic friction of the polarizing plate, which is an adherend when the surface protective film is adhered and then peeled off. It is to provide a surface protective film for polarizing plates which can reduce and achieve both the curling adjustment property of the polarizing plate and the sliding properties of the polarizing plate.

That is, the surface protective film for polarizing plates of the present invention is a surface protective film for polarizing plates having an adhesive layer formed of an adhesive composition on one or both sides of the support film, wherein the adhesive composition is a monomer component, at least, having 1 to 14 carbon atoms. A (meth)acrylic polymer containing 50 to 99.9% by mass of a (meth)acrylic monomer having a phosphorus alkyl group, and a silicone compound represented by the following formula, with respect to 100 parts by mass of the (meth)acrylic polymer, the silicone compound It contains 0.01 parts by mass to less than 1 part by mass, and when 1 cm 2 of the adhesive area of the pressure-sensitive adhesive layer is bonded to a TAC polarizing plate, bonded at 23° C. for 30 minutes, and then stretched in the shear direction at a tensile speed of 0.06 mm/min. Shearing force is 15 N/cm 2 or more, and after bonding the surface of the pressure-sensitive adhesive layer to a TAC polarizing plate and bonding at 23° C. for 30 minutes, peeling the surface protective film for the polarizing plate from the TAC polarizing plate, and the pressure-sensitive adhesive layer of the TAC polarizing plate It is characterized in that the dynamic friction force when the luminance increasing film is brought into contact with the surface adhered to the surface and a load of 200 g is applied at a tensile speed of 100 mm/min in a direction parallel to the contact surface is 1 N or less. :

[In the formula, R and R'are a methyl group or a phenyl group, and R and R'may be the same or different. In addition, m is 0 to 3000, and n is 1 to 3000.]

In the surface protective film for polarizing plates of the present invention, it is preferable that the pressure-sensitive adhesive composition contains an alkylene oxide group-containing surfactant.

In the surface protective film for polarizing plates of the present invention, it is preferable that the pressure-sensitive adhesive composition contains an ionic compound.

In the surface protective film for polarizing plates of the present invention, it is preferable that the (meth)acrylic polymer contains a hydroxyl group-containing (meth)acrylic monomer as a monomer component.

In the surface protective film for polarizing plates of the present invention, it is preferable that the (meth)acrylic polymer contains a carboxyl group-containing (meth)acrylic monomer as a monomer component.

It is preferable that the polarizing plate of this invention is protected by the said surface protective film for polarizing plates.

The manufacturing method of the silicone compound transfer type polarizing plate of the present invention includes a step of bonding the surface of the pressure-sensitive adhesive layer of the surface protective film for polarizing plates to the surface of the polarizing plate, and peeling the surface protective film for polarizing plates from the surface of the polarizing plate, It is preferable to include the step of transferring the silicone compound contained in the pressure-sensitive adhesive layer of the surface protective film onto the surface of the polarizing plate.

Since the surface protective film for polarizing plates of the present invention is intended to improve shearing force, when bonding the surface protective film for polarizing plates to a thinned polarizing plate, the occurrence of curl of the polarizing plate can be suppressed, thereby providing a polarizing plate having excellent curl adjustability. It is useful because it can be obtained. In addition, even when the polarizing plate and the luminance raising film come into contact with each other when the liquid crystal display panel is assembled after the surface protective film for polarizing plates of the present invention is adhered to and peeled off the polarizing plate, the dynamic friction force in the polarizing plate can be reduced It is useful because it is difficult to cause scratches on the polarizing plate and has excellent sliding properties.

1 is a schematic cross-sectional view of a polarizing plate having a surface protective film for a polarizing plate according to a preferred embodiment of the present invention.
2 is an explanatory diagram showing a method of measuring a peeling electrification voltage.

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

<Overall structure of the surface protection film for polarizing plate (surface protection film)>

The surface protective film for polarizing plates of the present invention (hereinafter, simply referred to as ``surface protective film'' in some cases) is generally referred to as a surface protective film, an adhesive tape, an adhesive label, an adhesive film, etc., especially optical It is suitable as a surface protective film that protects the surface of an optical component at the time of processing or conveyance of a component (eg, an optical component used as a component of a liquid crystal display panel such as a polarizing plate and a wave plate). The pressure-sensitive adhesive layer in the surface protective film is typically formed continuously, but is not limited to such a form, and may be, for example, a pressure-sensitive adhesive layer formed in a regular or random pattern such as a dot shape or a stripe shape. In addition, the surface protection film disclosed herein may be a roll type or a single leaf type.

Typical configuration examples of the surface protection film (surface protection film) for a polarizing plate disclosed herein are those having an adhesive layer on one or both sides of a support film (substrate), an antistatic layer provided on one side of the support film, and an antistatic layer of the support film The thing provided with the pressure-sensitive adhesive layer provided on the surface of the opposite side to the hakama is mentioned. The surface protective film is used by adhering this pressure-sensitive adhesive layer to an adherend (polarizing plate to be protected). The surface protective film before use (that is, before adhesion to an adherend) may be in a form in which the surface of the pressure-sensitive adhesive layer (the surface of the adhesion to the adherend) is protected by a release liner in which at least the side of the pressure-sensitive adhesive layer is a release surface. Alternatively, the surface protection film may be wound in a roll shape so that the pressure-sensitive adhesive layer contacts the back surface of the support film (the surface of the antistatic layer) and the surface thereof is protected.

<Support film>

The surface protective film (surface protective film) for polarizing plates of the present invention is characterized by having an adhesive layer formed of an adhesive composition on one or both surfaces of a support film. The resin material constituting the support film may be used without particular limitation, but it is preferable to use a resin material having excellent properties such as transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property, flexibility, and dimensional stability. In particular, since the support film has flexibility, the pressure-sensitive adhesive composition can be applied by a roll coater or the like, and it is useful because it can be wound in a roll shape.

Examples of the supporting film (substrate) include polyester polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate; Cellulose polymers such as diacetyl cellulose and triacetyl cellulose; Polycarbonate polymer; Acrylic polymers such as polymethyl methacrylate; A plastic film composed of a resin material containing the like as a main resin component (a main component in the resin component, typically a component occupying 50% by mass or more) can be preferably used as the support film. Other examples of the resin material include styrene polymers such as polystyrene and acrylonitrile styrene copolymer; Olefin-based polymers such as polyethylene, polypropylene, polyolefin having a cyclic to norbornene structure, and ethylene-propylene copolymer; Vinyl chloride polymer; Amide polymers such as nylon 6, nylon 6,6, and aromatic polyamide; What makes etc. a resin material is mentioned. As another example of the resin material, imide polymer, sulfone polymer, polyether sulfone polymer, polyetheretherketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl buty Ral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, and epoxy-based polymers are mentioned. It may be a supporting film made of a blend of two or more of the above-described polymers.

As the support film, a plastic film made of a transparent thermoplastic resin material can be preferably used. Among the said plastic films, it is a more preferable aspect to use a polyester film. Here, the polyester film refers to a polymer material (polyester resin) having a main skeleton based on ester bonds such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate as the main resin component. Say what to do. While such a polyester film has desirable properties as a support film for a surface protection film, such as having excellent optical properties and dimensional stability, it has properties that are easily charged as it is.

Various additives, such as an antioxidant, an ultraviolet absorber, a plasticizer, and a colorant (pigment, dye, etc.), may be blended with the resin material which comprises the said support film as needed. On one side of the support film (the surface on which the adhesive layer is provided), known or commonly used surface treatment, such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, application of a primer, etc. It may be implemented. Such surface treatment may be, for example, a treatment for increasing the adhesion between the support film and the pressure-sensitive adhesive layer (seepage property of the pressure-sensitive adhesive layer). A surface treatment such as introducing a polar group such as a hydroxyl group to the surface of the support film can be preferably employed.

In addition, the surface protective film of the present invention may have an antistatic layer on the side opposite to the pressure-sensitive adhesive layer of the support film, but when it has an antistatic function, a plastic film obtained by antistatic treatment is used as the support film. It is also possible to do. The use of the support film is preferable because charging of the surface protection film itself when peeled off is suppressed. Further, the support film is a plastic film, and by subjecting the plastic film to an antistatic treatment, it is possible to reduce the charge of the surface protective film itself and to have an excellent antistatic function to the adherend. In addition, as a method of imparting an antistatic function, there is no particular limitation, and a conventionally known method can be used. For example, an antistatic resin composed of an antistatic agent and a resin component, a conductive polymer, or a conductive resin containing a conductive material is applied. A method, a method of depositing or plating a conductive material, and a method of striking an antistatic agent or the like may be mentioned.

The thickness of the supporting film is usually about 1 µm to 200 µm, preferably about 5 µm to 100 µm. When the thickness of the support film is within the above range, it is preferable because the bonding workability to the polarizing plate as an adherend and peeling workability from the adherend are excellent.

<Adhesive composition>

The surface protective film (surface protective film) for polarizing plates of the present invention has the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition includes a (meth)acrylic polymer.

The pressure-sensitive adhesive composition used in the present invention contains, as a monomer component, a (meth)acrylic polymer containing at least 50 to 99.9 mass% of a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms, and having an adhesive ( Although it does not specifically limit as long as it is a meth)acrylic-type polymer, As a monomer component, a (meth)acrylic-type monomer which has a C1-C14 alkyl group is used, Preferably it is a (meth)acrylic-type monomer which has a C4-C14 alkyl group. As said (meth)acrylic monomer, 1 type or 2 or more types can be used as a main component. In addition, 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 a methacrylate. In addition, the main component refers to the component that is most often blended among the components.

The surface protective film of the present invention contains 50% by mass to 99.9% by mass of a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms, based on the total amount of the monomer components constituting the (meth)acrylic polymer, Preferably, they are 60 mass% to 99 mass%, more preferably 70 mass% to 98 mass%, and most preferably 80 mass% to 97 mass%. By being in the said range, the adhesive composition has suitable wettability, and the cohesive strength of an adhesive (layer) is also excellent, and it is preferable.

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)acrylic. Rate, 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-tri Decyl (meth)acrylate, n-tetradecyl (meth)acrylate, etc. are mentioned.

Among them, when used as the surface protective film of the present invention, 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)acrylic (Meth)acrylates having an alkyl group having 6 to 14 carbon atoms such as acrylate and n-tetradecyl (meth)acrylate are included as suitable ones. By using a (meth)acrylate having an alkyl group having 6 to 14 carbon atoms, it becomes easy to control the adhesion to the adherend to be low, and the re-peelability is excellent.

In the surface protective film of the present invention, it is preferable that the (meth)acrylic polymer contains a hydroxyl group-containing (meth)acrylic monomer as a monomer component. Since the said hydroxyl group can easily control crosslinking, it is a preferable aspect. In addition, it is possible to improve the shear force of the pressure-sensitive adhesive (layer), and by bonding the pressure-sensitive adhesive to the adherend, curling based on the adherend can be suppressed, and the occurrence of slip or deviation between the pressure-sensitive adhesive and the adherend (interface) It is preferable because it can suppress.

In addition, since the (meth)acrylic polymer uses the hydroxyl group-containing (meth)acrylic monomer as a monomer component, it becomes easier to control the crosslinking of the pressure-sensitive adhesive composition, and further improves the wettability due to flow and the pressure-sensitive adhesive ( It becomes easy to control the balance of cohesive force and shear force of the layer). In addition, when an antistatic agent is added to the pressure-sensitive adhesive, it is generally different from a carboxyl group or a sulfonate group that can act as a crosslinking site, and the hydroxyl group has an appropriate interaction with an ionic compound, which is an antistatic agent. It can also be used suitably.

The surface protective film of the present invention preferably contains a hydroxyl group-containing (meth)acrylic monomer in an amount of 0.1 to 20% by mass, more preferably, with respect to the total amount of the monomer component constituting the (meth)acrylic polymer. Is 1% by mass to 15% by mass, more preferably 2% by mass to 12% by mass. If it is within the above range, it is preferable because it becomes easy to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force and shear force of the pressure-sensitive adhesive (layer).

As the hydroxyl group-containing (meth)acrylic monomer, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxy Roxyhexyl (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 the surface protective film of the present invention, it is preferable that the (meth)acrylic polymer contains a carboxyl group-containing (meth)acrylic monomer as a monomer component. Since the carboxyl group can improve shearing force or prevent an increase in adhesive force over time, it is a preferred embodiment. In particular, by improving the shear force of the pressure-sensitive adhesive (layer), by bonding the pressure-sensitive adhesive to the adherend, curls based on the adherend can be suppressed, thereby suppressing the occurrence of slipping or deviation between the pressure-sensitive adhesive and the adherend (interface). It can be done and is preferable.

In addition, when the (meth)acrylic polymer uses the carboxyl group-containing (meth)acrylic monomer as a monomer component, it is possible to suppress an increase in the adhesive strength over time of the surface protective film (adhesive layer), and re-peelability, It is preferable because it is excellent in prevention of adhesion increase and workability, and also excellent in shearing force as well as cohesion of the pressure-sensitive adhesive layer.

The surface protective film of the present invention preferably contains less than 2% by mass of a carboxyl group-containing (meth)acrylic monomer, more preferably 0.001% by mass to 1.5% with respect to the total amount of the monomer components constituting the (meth)acrylic polymer. It is mass%, more preferably 0.005 mass% to 1 mass%, most preferably 0.01 mass% to 0.5 mass%. If it is within the above range, it is possible to suppress an increase in adhesive force over time, and is excellent in re-peelability, resistance to increase in adhesive force, and workability. In addition, the cohesive force of the pressure-sensitive adhesive layer and shear force are also excellent, which is preferable. In addition, when a large number of acid functional groups such as a carboxyl group having a large polar action are present, when an ionic compound is mixed as an antistatic agent, the acid functional group such as a carboxyl group interacts with the ionic compound, thereby preventing ionic conduction and reducing the conduction efficiency. It is not preferable because there is a possibility that it may decrease and sufficient antistatic properties may not be obtained.

Examples of the carboxyl group-containing (meth)acrylic monomer include (meth)acrylic acid, carboxylethyl (meth)acrylate, carboxylpentyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2 -(Meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid, Carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyltetrahydrophthalic acid, etc. are mentioned.

In addition, as other polymerizable monomer components, the glass transition temperature (Tg) of 0°C or less (usually -100°C or more) is made so that the glass transition temperature of the (meth)acrylic polymer is made so that it is easy to balance the adhesion performance. B. Polymerizable monomers for adjusting the releasability can be used within a range that does not impair the effects of the present invention.

Examples of other polymerizable monomers other than the hydroxyl group-containing (meth)acrylic monomer, the carboxyl group-containing (meth)acrylic monomer, and the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms used in the (meth)acrylic polymer , As long as it is within the range which does not impair the characteristic of this invention, it can use without limitation in particular. For example, components for improving cohesive strength and heat resistance such as cyano group-containing monomers, vinyl ester monomers, and aromatic vinyl monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, N-acryloylmorpholine, vinyl A component having a functional group that improves adhesion (adhesion) such as an ether monomer or acts as a starting point for crosslinking can be suitably used. These polymerizable monomers may be used alone or in combination of two or more.

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

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

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

Examples of the amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-di Ethylacrylamide, N,N-diethylmethacrylamide, N,N'-methylenebisacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, diacetoneacrylamide, etc. Can be mentioned.

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

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

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

In the present invention, other polymerizable monomers other than the carboxyl group-containing (meth)acrylic monomer, the hydroxyl group-containing (meth)acrylic monomer, and the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms are the (meth) It is preferable that it is 0 mass%-40 mass %, and it is more preferable that it is 0 mass%-30 mass% of the total amount (total monomer components) of the monomer components constituting the acrylic polymer. By using the above other polymerizable monomers within the above range, good interaction with an ionic compound that can be used as an antistatic agent and good re-peelability can be appropriately controlled.

The (meth)acrylic polymer has a weight average molecular weight of 100,000 to 5 million, preferably 200,000 to 4 million, and more preferably 300,000 to 3 million. When the weight average molecular weight is less than 100,000, the cohesive force of the pressure-sensitive adhesive (layer) to be obtained tends to be small, resulting in a tendency to generate residual glue. On the other hand, when the weight average molecular weight is more than 5 million, the fluidity of the polymer decreases, and the wettability to the adherend (polarizing plate) becomes insufficient, which tends to cause bubbles generated between the adherend and the pressure-sensitive adhesive composition layer of the surface protection film. There is this. In addition, a weight average molecular weight means what was obtained by measuring by GPC (gel permeation chromatography).

In addition, the glass transition temperature (Tg) of the (meth)acrylic polymer is preferably 0°C or less, more preferably -10°C or less, and still more preferably -20°C or less (usually -100°C or more). . When the glass transition temperature is higher than 0°C, it is difficult for the polymer to flow, for example, the wetting to the adherend (polarizing plate) is insufficient, which tends to cause bubbles generated between the adherend and the pressure-sensitive adhesive composition layer of the surface protection film. . In particular, by setting the glass transition temperature to -61°C or less, it becomes easy to obtain a pressure-sensitive adhesive composition excellent in wettability and light peelability to an adherend. In addition, 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 to be used.

The polymerization method of the (meth)acrylic polymer used in the present invention is not particularly limited, and polymerization can be performed according to known methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. Solution polymerization is a more preferred embodiment from the viewpoint of characteristics such as low contamination to (polarizing plate). Further, the polymer obtained may be any of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer.

<Silicone compound>

The surface protective film of the present invention is characterized in that the pressure-sensitive adhesive composition contains a silicone compound represented by the following formula. By using the above silicone compound, the detailed reason is not clear, but since the ether group is not contained in the molecular skeleton, it is possible to suppress a decrease in the elastic modulus of the obtained pressure-sensitive adhesive (layer), so that a decrease in cohesive force and shear force is not caused. When the surface protective film is bonded to the thinned polarizing plate, the occurrence of curl of the polarizing plate can be suppressed, and a polarizing plate excellent in curl control can be obtained:

In the above formula, R and R'are methyl groups or phenyl groups, and R and R'may be the same or different. In addition, m is 0 to 3000, and n is 1 to 3000.

In addition, specific examples of the silicone compound as a commercial product include, for example, KF-50-100cs (methylphenyl silicone oil), KF-50-300cs (methylphenyl silicone oil), KF-50-1000cs (methylphenyl silicone oil), and KF- 50-3000cs (methylphenyl silicone oil), KF-53 (methylphenyl silicone oil), KF-54 (methylphenyl silicone oil), KF-96-100cs (dimethyl silicone oil), KF-96-300cs (methylphenyl silicone oil), KF -96-1000 cs (dimethyl silicone oil), KF-96-3000 cs (dimethyl silicone oil), KF-96-1 10,000 cs (dimethyl silicone oil) (manufactured by Shin-Etsu Chemical Corporation), and the like.

In the surface protective film of the present invention, the pressure-sensitive adhesive composition contains 0.01 parts by mass to less than 1 part by mass of the silicone compound, preferably 0.02 parts by mass to 0.98 parts by mass, based on 100 parts by mass of the (meth)acrylic polymer. Parts, more preferably 0.03 parts by mass to 0.96 parts by mass. If it is within the above range, it is possible to achieve both shear force and dynamic friction force, and excellent low fouling property is preferable.

<Alkylene oxide group-containing surfactant>

In the surface protective film of the present invention, it is preferable that the pressure-sensitive adhesive composition contains an alkylene oxide group-containing surfactant. By containing an alkylene oxide group-containing surfactant in the pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer having excellent wettability to a polarizing plate as an adherend can be obtained, which is useful.

Specific examples of the alkylene oxide group-containing surfactant include, for example, polyoxyalkylene alkylamine, polyoxyalkylenediamine, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, and polyoxyalkylene alkylphenyl ether. , Nonionic surfactants such as polyoxyalkylene alkyl ether, polyoxyalkylene alkyl allyl ether, and polyoxyalkylene alkylphenyl allyl ether; Anionic surfactants such as polyoxyalkylene alkyl ether sulfate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether sulfate, and polyoxyalkylene alkyl phenyl ether phosphate; In addition, cationic surfactants and amphoteric surfactants having a polyoxyalkylene chain (polyalkylene oxide chain) can be mentioned. Further, the alkylene oxide group-containing surfactant may be used singly or in combination of two or more.

As a preferred embodiment, the alkylene oxide group-containing surfactant is a compound having a (poly)ethylene oxide chain at least in part. By blending the compound having the (poly)ethylene oxide chain, in the case of blending an antistatic agent in addition to the base polymer, compatibility with the antistatic agent is improved, bleeding to the polarizing plate as an adherend is suitably suppressed. A fouling adhesive composition is obtained. As the (poly) ethylene oxide chain-containing compound, the mass of the (poly) ethylene oxide chain occupied by the entire compound is preferably 5% by mass to 90% by mass, more preferably 5% by mass to 85% by mass, further It is preferably 5% by mass to 80% by mass, most preferably 5% by mass to 75% by mass.

The number average molecular weight (Mn) of the alkylene oxide group-containing surfactant is preferably 50000 or less, more preferably 200 to 30000, still more preferably 200 to 10000, and particularly preferably 200 to 5000. . When the number average molecular weight is too large than 50000, the compatibility with the acrylic polymer decreases and the pressure-sensitive adhesive layer tends to whiten. When the number average molecular weight is too small than 200, contamination by the polyoxyalkylene compound may be liable to occur. In addition, the number average molecular weight here means a value in terms of polystyrene obtained by GPC (gel permeation chromatography).

In addition, specific examples of the alkylene oxide group-containing surfactant as a commercial product include, for example, Aqualon KH-10, Aqualon HS-10, Neugen EA-137, Hytenol NF-08 (manufactured by Daiichi Kogyo Co., Ltd.), and Latte. Water PD-420 (made by Kao Corporation), etc. are mentioned.

The content of the alkylene oxide group-containing surfactant may be, for example, 0 to 5 parts by mass, preferably 0.01 to 2 parts by mass, more preferably, based on 100 parts by mass of the (meth)acrylic polymer. Is 0.05 parts by mass to 1 part by mass. Within the above range, when an antistatic agent is added, an effect of preventing bleeding of the antistatic agent can be obtained, which is preferable.

Further, the pressure-sensitive adhesive composition may contain an acrylic oligomer. As for the acrylic oligomer, the weight average molecular weight (Mw) is preferably 1000 or more and less than 30000, more preferably 1500 or more and less than 20000, and still more preferably 2000 or more and less than 10,000. When it is used for the acrylic pressure-sensitive adhesive composition for surface protection use (for re-peel) of the present embodiment, it functions as a tackifying resin, improves adhesion (adhesion) properties, and is effective in suppressing floating of the surface protective film.

In the acrylic oligomer, a (meth)acrylic acid ester monomer may be used. For example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, ( Isobutyl meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate , Heptyl (meth)acrylate, octyl (meth)acrylate, isoctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, (meth) (Meth)acrylate alkyl esters such as undecyl acrylate and dodecyl (meth)acrylate;

(Meth)acrylate aryl esters such as phenyl (meth)acrylate and benzyl (meth)acrylate;

(Meth)acrylic acid ester obtained from a terpene compound derivative alcohol, etc. are mentioned.

In addition, as the acrylic oligomer, a (meth)acrylic monomer having an alicyclic structure may be used. For example, dicyclopentanyl methacrylate, dicyclopentanyl acrylate, dicyclopentanyloxyethyl methacrylate, dicyclopentanyloxy Ethyl acrylate, tricyclopentanyl methacrylate, tricyclopentanyl acrylate, 1-adamantyl methacrylate, 1-adamantyl acrylate, 2-methyl-2-adamantyl methacrylate, 2-methyl (Meth)acrylic acid esters, such as 2-adamantyl acrylate, 2-ethyl-2-adamantyl methacrylate, and 2-ethyl-2-adamantyl acrylate, etc. are mentioned. These (meth)acrylic monomers can be used alone or in combination of two or more.

In addition, the acrylic oligomer may be obtained by copolymerizing other monomer components (copolymerizable monomer) copolymerizable with the (meth)acrylic monomer in addition to the (meth)acrylic monomer component unit.

The weight average molecular weight (Mw) of the acrylic oligomer is 1000 or more and less than 30000, preferably 1500 or more and less than 20000, and more preferably 2000 or more and less than 10000. When the weight average molecular weight is 30000 or more, adhesion (adhesion) property decreases. Moreover, when the weight average molecular weight is less than 1000, since it becomes a low molecular weight, the adhesive force of a surface protective film falls.

In the surface protective film of the present invention, it is preferable that the pressure-sensitive adhesive composition does not contain an organopolysiloxane having a polyoxyalkylene chain. By using the organopolysiloxane, light peeling of the surface protective film (adhesive layer) and the dynamic friction force in the polarizing plate can be suppressed to a low level, but on the other hand, the shear force decreases, resulting in an undesirable aspect. In addition, the detailed reason for the decrease in shear force is not clear, but it is assumed that the elastic modulus of the obtained pressure-sensitive adhesive (layer) is lowered, resulting in a decrease in cohesive force and shear force, since the silicone component is included in the skeleton in addition to the ether group. .

<Antistatic agent>

In the surface protective film of the present invention, the pressure-sensitive adhesive composition may contain an antistatic agent (antistatic component), and may contain an ionic compound as the antistatic agent. Examples of the ionic compound include an alkali metal salt and/or an ionic compound (such as an ionic liquid) having a low melting point (melting point of 150°C or less). By containing these ionic compounds, it is possible to impart excellent antistatic properties.

In addition, with respect to 100 parts by mass of the (meth)acrylic polymer, the content of the antistatic agent is preferably 1 part by mass or less, more preferably 0.001 parts by mass to 0.9 parts by mass, and still more preferably 0.005 parts by mass to 0.8 parts by mass. It is wealth. If it is within the above range, it is preferable because it is easy to achieve both antistatic properties and low fouling properties.

<crosslinking agent>

As for the surface protective film of this invention, it is preferable that the said adhesive composition contains a crosslinking agent. Moreover, in this invention, it is set as the adhesive layer using the said adhesive composition. For example, when the pressure-sensitive adhesive composition contains the (meth)acrylic polymer, by appropriately adjusting the constituent units of the (meth)acrylic polymer, the composition ratio, the selection and addition ratio of the crosslinking agent, and crosslinking, it is more excellent in heat resistance. A surface protection film (adhesive agent layer) can be obtained.

As the crosslinking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine-based resin, an aziridine derivative, a metal chelate compound, or the like may be used. In particular, the use of an isocyanate compound is a preferred embodiment. 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 dimer acid diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate ( IPDI) and other alicyclic isocyanates, 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, aromatic isocyanates such as xylylene diisocyanate (XDI), and allophanate bonding of the isocyanate compound, And polyisocyanate modified products modified by a biuret bond, isocyanurate bond, uretdione bond, urea bond, carbodiimide bond, uretonimine bond, oxadiazinetrione bond, or the like. For example, as commercially available products, brand names Takenate 300S, Takenate 500, Takenate D165N, Takenate D178N (above, manufactured by Mitsui Chemical), Sumdule T80, Sumdule L, Death Module N3400 (above, manufactured by Sumika Bayer Urethane) , Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (above, manufactured by Nippon Polyurethane Co., Ltd.), 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 crosslinking agent in combination, it becomes possible to achieve both adhesiveness and repellency (adhesion to curved surfaces), and a surface protective film (adhesive layer) having more excellent adhesion reliability can be obtained.

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

Examples of the melamine resin include hexamethylol melamine. Examples of the aziridine derivative include commercially available products such as HDU, TAZM, and TAZO (above, manufactured by Sogo Yakko).

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

The content of the crosslinking agent used in the present invention is preferably 0.01 parts by mass to 10 parts by mass, and more preferably 0.5 parts by mass to 8 parts by mass based on 100 parts by mass of the (meth)acrylic polymer. It is preferable, and it is more preferable to contain 1 to 5 parts by mass. When the content is less than 0.01 parts by mass, crosslinking formation by the crosslinking agent is insufficient, the cohesive force of the obtained pressure-sensitive adhesive layer is small, and sufficient heat resistance is not obtained in some cases, and there is a tendency to become a cause of residual paste. On the other hand, when the content exceeds 10 parts by mass, the cohesive force of the polymer is large, the fluidity decreases, the wetting to the adherend (polarizing plate) is insufficient, and the cause of bubbles generated between the adherend and the pressure-sensitive adhesive layer (adhesive composition layer) is caused. Tend to be. Further, when the amount of the crosslinking agent is large, there is a tendency for the peeling and charging properties to decrease. In addition, these crosslinking agents may be used alone or in combination of two or more.

In the pressure-sensitive adhesive composition, a crosslinking catalyst may be further contained in order to more effectively advance any one of the aforementioned crosslinking reactions. As such a crosslinking catalyst, for example, tin catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris(acetylacetonato) iron, tris(hexane-2,4-dionato) iron, tris(heptane-2 ,4-Dionato) iron, tris (heptane-3,5-dionato) iron, tris (5-methylhexane-2,4-dionato) iron, tris (octane-2,4-dionato) iron, Tris (6-methylheptane-2,4-dionato) iron, tris (2,6-dimethylheptane-3,5-dionato) iron, tris (nonane-2,4-dionato) iron, tris (nonane -4,6-Dionato) iron, tris (2,2,6,6-tetramethylheptane-3,5-dionato) iron, tris (tridecane-6,8-dionato) iron, tris (1 -Phenylbutane-1,3-dionato) iron, tris (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 (propionyl methyl acetate) iron, tris (propionyl ethyl acetate) ) Iron, tris (propionyl acetate-n-propyl) iron, tris (propionyl isopropyl acetate) 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 (diethyl malonate) iron, trimethoxy iron, triethoxy iron, triisopropoxy iron And iron-based catalysts such as ferric chloride can be used. These crosslinking catalysts may be used alone or in combination of two or more.

Although the content of the crosslinking catalyst is not particularly limited, for example, with respect to 100 parts by mass of the (meth)acrylic polymer, approximately 0.0001 parts by mass to 1 part by mass, more preferably 0.001 parts by mass to 0.5 parts by mass. If it is within the above range, when the pressure-sensitive adhesive layer is formed, the speed of the crosslinking reaction is fast, and the pot life of the pressure-sensitive adhesive composition is also long, resulting in a preferred embodiment.

In addition, the pressure-sensitive adhesive composition may contain a compound that generates keto-enol tautomerism as a crosslinking retarder. For example, in the pressure-sensitive adhesive composition containing a crosslinking agent or in the pressure-sensitive adhesive composition that can be used by blending a crosslinking agent, an aspect including a compound that generates the keto-enol tautomerism can be preferably employed. Thereby, the effect of suppressing excessive viscosity increase or gelation of the pressure-sensitive adhesive composition after compounding the crosslinking agent and extending the pot life of the pressure-sensitive adhesive composition can be realized. In the case of using at least an isocyanate compound as the crosslinking agent, it is particularly significant to contain a compound that generates keto-enol tautomerism. This technique can be preferably applied, for example, when the pressure-sensitive adhesive composition is in the form of an organic solvent solution or a non-solvent.

As the compound generating the keto-enol tautomerism, various β-dicarbonyl compounds can be used. As a specific example, acetylacetone, 2,4-hexanedione, 3,5-heptanedione, 2-methylhexane-3,5-dione, 6-methylheptane-2,4-dione, 2,6-dimethylheptane-3 Β-diketones such as ,5-dione; Acetoacetate esters such as methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, and tert-butyl acetoacetate; Propionyl acetate, such as propionyl methyl acetate, propionyl ethyl acetate, propionyl isopropyl acetate, and tert-butyl propionyl acetate; Isobutyryl acetate, such as isobutyryl methyl acetate, isobutyryl ethyl acetate, isobutyl isopropyl acetate, and tert-butyl isobutyryl acetate; Malonic acid esters, such as methyl malonate and ethyl malonate, etc. are mentioned. Among them, suitable compounds include acetylacetone and acetoacetic acid esters. The compounds generating such keto-enol tautomerism may be used alone or in combination of two or more.

The content of the compound that generates the keto-enol tautomerism may be, for example, 0.1 to 20 parts by mass, and usually 0.5 to 15 parts by mass (for example, 1 part by mass) based on 100 parts by mass of the (meth)acrylic polymer. It is suitable to set it as mass parts-10 mass parts). When the amount of the compound is too small, it may become difficult to exhibit a sufficient effect of use. On the other hand, when the above compound is used more than necessary, it may remain in the pressure-sensitive adhesive layer and lower the cohesive strength.

In addition, the pressure-sensitive adhesive composition used in the surface protective film of the present invention may contain other known additives, such as powders such as colorants and pigments, plasticizers, tackifiers, low molecular weight polymers, surface lubricants, leveling agents , Antioxidants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, inorganic or organic fillers, metal powders, particles, foils, etc., can be added appropriately depending on the purpose of use. have.

The surface protective film of the present invention is characterized by having an adhesive layer formed from the adhesive composition (formed by crosslinking the adhesive composition) on one or both surfaces of the support film. Crosslinking of the pressure-sensitive adhesive composition is generally performed after application of the pressure-sensitive adhesive composition, but it is also possible to transfer the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition after crosslinking to a support film or the like. In addition, the method of forming the pressure-sensitive adhesive layer on the support film is not particularly described, but is produced by, for example, applying the pressure-sensitive adhesive composition to the support film and drying and removing a polymerization solvent to form a pressure-sensitive adhesive layer on the support film. Thereafter, curing may be performed for the purpose of adjusting the component migration of the pressure-sensitive adhesive layer or adjusting the crosslinking reaction. In addition, when the pressure-sensitive adhesive composition is applied on a support film to prepare a surface protective film, one or more solvents other than a polymerization solvent may be newly added to the pressure-sensitive adhesive composition so that it can be uniformly applied on the support film.

In addition, as a method for forming the pressure-sensitive adhesive layer when producing the surface protective film of the present invention, a known method used for producing pressure-sensitive adhesive sheets (surface protective films) is used. Specifically, for example, a roll coat, a gravure coat, a reverse coat, a roll brush, a spray coat, an air knife coat method, an extrusion coat method using a die coater or the like can be mentioned.

In general, the surface protective film of the present invention is produced so that the thickness of the pressure-sensitive adhesive layer is 3 µm to 100 µm, more preferably about 5 µm to 50 µm. When the thickness of the pressure-sensitive adhesive layer is within the above range, it is preferable because it is easy to obtain an appropriate balance of re-peelability and adhesion (adhesion) properties.

<Separator>

In the surface protective film of the present invention, if necessary, for the purpose of protecting the adhesive surface of the adhesive layer, it is possible to bond a separator to the surface of the adhesive layer.

Although paper or plastic film is used as a material constituting the separator, a plastic film is suitably used in view of excellent surface smoothness. The film is not particularly limited as long as it is a film capable of protecting the pressure-sensitive adhesive layer, and for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer Films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, ethylene-vinyl acetate copolymer films, and the like.

The thickness of the separator is usually 5 µm to 200 µm, preferably about 10 µm to 100 µm. If it is within the said range, since it is excellent in bonding workability to an adhesive layer and peeling workability from an adhesive layer, it is preferable. The separator may be subjected to a release and antifouling treatment with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based releasing agent, silica powder, or the like, or an antistatic treatment such as a coating type, a paste type, and a vapor deposition type, if necessary.

In addition to the support film (substrate) and the pressure-sensitive adhesive layer, the surface protective film of the present invention can be implemented even in an aspect including other layers such as an antistatic layer.

<polarizing plate>

It is preferable that the polarizing plate of this invention is protected by the said surface protection film for polarizing plates (surface protection film). Since the surface protection film can improve the shearing force, when the surface protection film for polarizing plates is bonded to the thinned polarizing plate, the occurrence of curl of the polarizing plate can be suppressed, and a polarizing plate excellent in curl control can be obtained. So it is useful. In addition, after the surface protection film is adhered to the polarizing plate and peeled off, when assembling a liquid crystal display panel, even when the polarizing plate and the luminance increasing film come into contact, the dynamic friction force in the polarizing plate can be suppressed low. It is useful because it is difficult to cause scratches on the polarizing plate and has excellent sliding properties. In addition, as shown in Fig. 1, the polarizing plate (polarizing plate 5 having a surface protective film) adheres the surface of the pressure-sensitive adhesive layer 3 of the surface protective film 1 for polarizing plates to the surface of the polarizing plate 2 Thus, the surface of the polarizing plate is protected from scratches and dust.

<Method of manufacturing a silicon compound transfer type polarizing plate>

The manufacturing method of the silicone compound transfer type polarizing plate of the present invention includes a step of bonding the surface of the pressure-sensitive adhesive layer of the surface protective film for polarizing plate to the surface of the polarizing plate, and peeling the surface protective film for polarizing plate from the surface of the polarizing plate, It is preferable to include a step of transferring the silicone compound contained in the pressure-sensitive adhesive layer of the surface protective film onto the surface of the polarizing plate. By adhering the surface of the pressure-sensitive adhesive layer to the surface of the polarizing plate, a silicone compound that does not contain an ether group segregated on the surface of the pressure-sensitive adhesive layer is transferred to the surface of the polarizing plate, and then the surface protective film is peeled off. , Since a trace amount of the silicone compound remains on the surface of the polarizing plate, the obtained polarizing plate can suppress the dynamic friction to a low level, and even when the polarizing plate and the luminance raising film are in contact with each other, it is difficult to cause scratches on the polarizing plate itself. Excellent and useful.

In the step of bonding the surface of the pressure-sensitive adhesive layer of the surface protective film for polarizing plates to the surface of the polarizing plate, the bonding time is not particularly limited, but, for example, it is preferably bonded for 15 minutes or more under conditions of 50% RH at 23°C. Do. If it is within the above range, the silicone compound can be sufficiently transferred (transferred) from the pressure-sensitive adhesive surface to the surface of the polarizing plate, resulting in a preferred embodiment.

Example

Hereinafter, examples and the like specifically showing the configuration and effects of the present invention will be described, but the present invention is not limited thereto. In addition, about the compounding content and characteristic evaluation in Examples etc., it measured as follows. In addition, Table 1 shows the blending ratio of the pressure-sensitive adhesive composition and the physical properties of the obtained (meth)acrylic polymer, and Table 2 shows the obtained surface protective film (surface protective film) for polarizing plates and the evaluation of characteristics in the polarizing plate after bonding the surface protective film. The results are shown.

<Evaluation>

Below, a specific measurement and evaluation method is described.

<Measurement of weight average molecular weight (Mw)>

The weight average molecular weight (Mw) was measured using the Tosoh Corporation GPC apparatus (HLC-8220GPC). 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℃

column:

Sample column; TSK guardcolumn Super HZ-H (1EA) + TSK gel Super HZM-H (2EA)

Reference column; TSK gel Super H-RC (1ea)

Detector: differential refractometer (RI)

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

<Theoretical value of glass transition temperature (Tg)>

The glass transition temperature Tg (°C) was determined according to the following equation using the following literature values as the glass transition temperature [Tgn (°C)] of the homopolymer by each monomer.

Equation: 1/(Tg + 273) = Σ[Wn/(Tgn + 273)]

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

Literature value:

2-ethylhexylacrylate (2EHA): -70°C

Acrylic acid (AA): 106℃

2-hydroxyethyl acrylate (HEA): -15°C

4-hydrokibutylacrylate (4HBA): -32°C

In addition, as literature values, "Synthesis, design and credit development of acrylic resins" (published by Central Management Development Center Publishing Department) and "Polymer Handbook" (John Wiley & Sons) were referenced.

<Measurement of shear force>

After the surface protection film was cut to a size of 10 mm in width and 100 mm in length, and the separator adhered to the surface of the pressure-sensitive adhesive layer of the surface protective film was peeled off, the adhesion (adhesion) area of the pressure-sensitive adhesive layer of the surface protective film was 1 cm 2 TAC (triacetyl cellulose) polarizing plate (manufactured by Nitto Denko, SEG1423DU polarizing plate, width: 25 mm, length: 100 mm) was bonded to, and allowed to stand at room temperature (23° C.×50% RH) for 30 minutes, and then stretched. It was pulled in the shear direction at a speed of 0.06 mm/min, and the maximum load (N/cm 2) at that time was taken as the shear force.

Further, the shear force (N/cm 2) is 15 or more, preferably 15 to 50, and more preferably 20 to 40. If the shearing force is within the above range, it can withstand the force in the shearing direction that occurs when the polarizing plate, which is the adherend to which the surface protection film is adhered, attempts to curl, so that slipping or deviation of the surface protection film does not occur, and curling of the adherend is suppressed. It is desirable because it can.

<Measurement of dynamic friction (slidability)>

Attach the surface of the adhesive layer of the surface protection film to the entire TAC surface of a TAC polarizing plate (manufactured by Nitto Denko, SEG1423DU polarizing plate) cut into a size of 5 cm in width and 15 cm in length, and left at 23°C×50% RH for 30 minutes After that, the surface protective film was peeled off from the TAC surface.

Next, the surface to which the pressure-sensitive adhesive layer surface of the TAC polarizing plate was adhered (TAC surface) and the luminance increasing film (manufactured by Sumitomo 3M, DBEF-D2-280) were brought into contact with each other to obtain a test piece. A load of 200 g was placed on this test piece. The load-bearing test piece was attached to a tensile tester using a non-stretchable thread, and at a measurement temperature of 25°C, the contact surface of the TAC surface and the luminance-increasing film under the conditions of a tensile speed of 100 mm/min and a tensile distance of 50 mm and It stretched in the parallel direction (horizontal direction), and the average value (n=3) of the dynamic friction force (N) with respect to a test piece was calculated|required.

Further, the dynamic friction force (N) is 1 or less, preferably 0.9 or less, and more preferably 0.8 or less. If it is within the above range, the dynamic friction force in the polarizing plate can be reduced, the scratch generated on the surface of the polarizing plate can be suppressed, and the sliding property can be improved and advantageous.

<having wound or not>

After measuring the dynamic friction, the state of the wound on the surface of the TAC polarizing plate (TAC surface) was visually observed.

If there is no wound: ○, if a wound has occurred: ×

<Measurement of peeling large voltage>

A surface protection film (surface protection film) for a polarizing plate was cut into a size of 70 mm in width and 130 mm in length, and the separator adhered to the surface of the pressure-sensitive adhesive layer of the surface protection film was peeled off, and then an acrylic plate (thickness: 2 Mm, width: 70 mm, length: 100 mm) a TAC polarizing plate (manufactured by Nitto Denko, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm), one end of 30 mm protrudes on the surface (TAC surface) It was compressed with a hand roller to come out. After leaving to stand at 23°C x 50% RH for 1 day, as shown in Fig. 2, a sample was set at a predetermined position. One end protruding by 30 mm was fixed to an automatic winder, and peeled so that the peeling angle was 150° and the peeling speed was 30 m/min. The electric potential on the surface of the polarizing plate generated at this time (peeling voltage: absolute value, kV) was measured with a potential measuring device (KSD-0103 manufactured by Kasuga Electric Corporation) fixed at the center of the polarizing plate. The measurement was performed in an environment of 23°C x 50% RH.

<Pollution>

A TAC polarizing plate (manufactured by Nitto Denko Co., Ltd.) cut into a width of 70 mm and a length of 100 mm after the surface protection film was cut into a size of 50 mm in width and 80 mm in length, and the separator adhered to the surface of the pressure-sensitive adhesive layer of the surface protection film was peeled off. , SEG1423DU polarizing plate) After adhering to the surface (TAC surface) and leaving to stand at 23°C x 50% RH for 1 day, the surface protection film was peeled off, and contamination was visually confirmed.

When there was no contamination: ○, When there was contamination: ×

<How to prepare>

Below, a method for preparing a specific (meth)acrylic polymer or an adhesive composition will be described. In addition, the blending amount (number of copies) in Table 1 indicated the solid content.

<Example 1>

<Preparation of (meth)acrylic polymer>

In a 4-neck flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and cooler, 100 parts by mass of 2-ethylhexyl acrylate (2EHA), 10 parts by mass of 4-hydroxybutyl acrylate (4HBA), and 0.02 of acrylic acid (AA) Part by mass, 0.2 parts by mass of 2,2'-azobisisobutyronitrile and 157 parts by mass of ethyl acetate are added as a polymerization initiator, and nitrogen gas is introduced while stirring slowly, and the liquid temperature in the flask is maintained at around 65°C. Time polymerization reaction was performed to prepare a (meth)acrylic polymer solution (40% by mass). The weight average molecular weight (Mw) of the acrylic polymer was 540,000, and the glass transition temperature (Tg) was -67°C.

<Preparation of adhesive composition>

The (meth)acrylic polymer solution (40% by mass) was diluted to 20% by mass with ethyl acetate, and to 500 parts by mass of this solution (100 parts by mass of solid content), polyoxyethylene-1-(allyl), a non-silicone polyether Oxymethyl) alkyl ether ammonium sulfate (Daiichi Kogyo Seiyaku, Aqualon KH-10) 0.3 parts by mass (solid content 0.3 parts by mass), methylphenyl silicone oil (Shin-Etsu Chemical Corporation, KF-) 50-100 cs) 0.1 parts by mass (solid content 0.1 parts by mass), lithium bis(trifluoromethanesulfonyl) imide (manufactured by Tokyo Chemical Industry Co., Ltd., LiTFSI) 0.15 parts by mass (solid content 0.15 parts by mass) ) And as a crosslinking agent, an isocyanurate body of hexamethylene diisocyanate which is an aliphatic isocyanate compound (manufactured by Tosoh Corporation, Coronate HX:C/HX) 3 parts by mass (solid content 3 parts by mass), dibutyl dilaurate as a crosslinking catalyst Tin (1 mass% ethyl acetate solution) 2 mass parts (solid content 0.02 mass parts) was added and mixed and stirred to prepare a pressure-sensitive adhesive composition (solution).

<Production of antistatic treatment film>

An antistatic agent solution was prepared by diluting 10 parts by weight of an antistatic agent (manufactured by Solvex, Microsolver RMd-142, containing tin oxide and polyester resin as main components) with a mixed solvent consisting of 30 parts by weight of water and 70 parts by weight of methanol. .

The obtained antistatic agent solution was applied onto a polyethylene terephthalate (PET) film (thickness: 38 μm) as a support film using a Mayer bar, and dried at 130° C. for 1 minute to remove the solvent to prevent an antistatic layer (thickness: 0.2 μm). ) To form an antistatic treatment film.

<Preparation of surface protective film for polarizing plate>

The pressure-sensitive adhesive composition (solution) was applied to the surface opposite to the antistatic layer of the antistatic treatment film, and heated at 130° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 15 μm. Next, a silicone-treated surface of a polyethylene terephthalate film (25 µm thick), which is a separator subjected to a silicone treatment on one side, was bonded to the surface of the pressure-sensitive adhesive layer to prepare a surface protective film for polarizing plates.

<Examples 2 to 8 and Comparative Examples 1 to 3>

Based on the mixing ratio of Table 1, it carried out similarly to Example 1, and produced the surface protective film for polarizing plates. In addition, the blending amount in Table 1 indicated solid content.

According to the evaluation method, the obtained surface protective film (surface protective film) for polarizing plates and the result of property evaluation in the polarizing plate after adhesion of the surface protective film were performed. Table 2 shows the obtained results.

The abbreviation in Table 1 is demonstrated below.

<Monomer component constituting (meth)acrylic polymer>

2EHA: 2-ethylhexylacrylate

AA: acrylic acid (carboxyl group-containing (meth)acrylic monomer)

HEA: 2-hydroxyethyl acrylate (hydroxyl group-containing (meth)acrylic monomer)

4HBA: 4-hydroxybutyl acrylate (hydroxyl group-containing (meth)acrylic monomer)

<crosslinking agent>

C/L: aromatic isocyanate compound, trimethylolpropane/tolylenediisocyanate trimer adduct, manufactured by Tosoh Corporation, brand name: Coronate L

C/HX: aliphatic isocyanate compound, isocyanurate of hexamethylene diisocyanate, manufactured by Tosoh Corporation, brand name: Coronate HX

<Polyether>

KH-10: Polyoxyethylene-1-(allyloxymethyl) alkyl ether ammonium sulfate, manufactured by Daiichi Kogyo Seiyaku, brand name: Aqualon KH-10

HS-10: Polyoxyethylene nonyl propenyl phenyl ether ammonium sulfate, manufactured by Daiichi Kogyo Seiyaku, brand name: Aqualon HS-10

NF-08: Polyoxyethylene styrenated phenyl ether ammonium sulfate, manufactured by Daiichi Kogyo Seiyaku, brand name: Hytenol NF-08

EA-137: Polyoxyethylene styrenated phenyl ether, manufactured by Daiichi Kogyo Seiyaku, brand name: Neugen EA-137

KF353: Polyether modified silicone, manufactured by Shin-Etsu Chemical Co., Ltd., brand name: KF-353

<Silicone compound>

KF-50-100cs: Methylphenyl silicone oil, manufactured by Shin-Etsu Chemical, brand name: KF-50-100cs

KF-50-1000cs: Methylphenyl silicone oil, manufactured by Shin-Etsu Chemical, brand name: KF-50-1000cs

KF-50-3000cs: Methylphenyl silicone oil, manufactured by Shin-Etsu Chemical, brand name: KF-50-3000cs

KF-96-100cs: Dimethyl silicone oil, manufactured by Shin-Etsu Chemical Company, brand name: KF-96-100cs

KF-96-1000cs: Dimethyl silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd., brand name: KF-96-1000cs

KF-96-3000cs: Dimethyl silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd., brand name: KF-96-3000cs

<Antistatic agent (ionic compound)>

LiTFSI: Lithium bis (trifluoromethanesulfonyl) imide, manufactured by Tokyo Kasei Co., Ltd.

From the evaluation results in Table 2, in all examples, by using a surface protective film for a polarizing plate having a pressure-sensitive adhesive layer containing a silicone compound that does not contain an ether group in the molecular skeleton, the desired shear force and dynamic friction force are obtained, and curl It was confirmed that coexistence of adjustability and slipperiness was achieved, and it was possible to suppress the occurrence of contamination and scratches on the polarizing plate.

On the other hand, from the results of Table 2, in Comparative Example 1, since the silicone compound was not blended, the dynamic friction force could not be suppressed low. In Comparative Example 2, it was confirmed that the shear force was lowered because the polyether-modified silicone was blended without blending the silicone compound. In addition, in Comparative Example 3, even though the silicone compound was used, it was confirmed that there was a problem in practical use because contamination was observed because it was blended in excess of a predetermined amount.

1: Surface protective film for polarizing plate (surface protective film)
2: polarizer
3: adhesive layer
4: support film
5: Polarizing plate (polarizing plate) having a surface protective film for polarizing plates
10: acrylic plate
20: TAC polarizer
30: sample holder
40: electric potential meter

Claims (7)

As a surface protective film for a polarizing plate having an adhesive layer formed of an adhesive composition on one or both sides of the support film,
The pressure-sensitive adhesive composition contains at least 50 to 97 mass% of a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a monomer component, 2 to 20 mass% of a hydroxyl group-containing (meth)acrylic monomer, and a carboxyl group containing (meth) ) A (meth)acrylic polymer containing less than 0.001 to 2% by mass of an acrylic monomer, and a silicone compound represented by the following formula, and containing from 0.01 parts by mass of the silicone compound to 100 parts by mass of the (meth)acrylic polymer It contains less than 1 part by mass,
The (meth)acrylic polymer does not contain a (meth)acrylic polymer having a weight average molecular weight of 1.5 million or more by gel permeation chromatography,
The adhesive area 1 cm ² of the pressure-sensitive adhesive layer was bonded to a TAC polarizing plate, bonded at 23° C. for 30 minutes, and then the shear force when tensioned in the shear direction at a tensile speed of 0.06 mm/min is 15 N/cm ² or more,
The surface of the pressure-sensitive adhesive layer was bonded to a TAC polarizing plate, bonded at 23° C. for 30 minutes, and then the surface protective film for polarizing plate was peeled off from the TAC polarizing plate, and the surface of the TAC polarizing plate was adhered to the surface of the pressure-sensitive adhesive layer. A surface protective film for a polarizing plate, characterized in that the dynamic friction force when the lifting film is brought into contact and a load of 200 g is applied at a tensile speed of 100 mm/min in a direction parallel to the contact surface is 1 N or less:

[In the formula, R and R'are a methyl group or a phenyl group, and R and R'may be the same or different. In addition, m is 0 to 3000, and n is 1 to 3000.] The surface protective film for a polarizing plate according to claim 1, wherein the pressure-sensitive adhesive composition contains an alkylene oxide group-containing surfactant. The surface protective film for polarizing plates according to claim 1 or 2, wherein the pressure-sensitive adhesive composition contains an ionic compound. A polarizing plate protected by the surface protective film for polarizing plates according to claim 1 or 2. A step of bonding the surface of the pressure-sensitive adhesive layer of the surface protective film for polarizing plates according to claim 1 or 2 to the surface of the polarizing plate, and
A step of peeling the surface protective film for a polarizing plate from the surface of the polarizing plate to transfer the silicone compound contained in the pressure-sensitive adhesive layer of the surface protective film for the polarizing plate to the surface of the polarizing plate
A method of manufacturing a silicon compound transfer type polarizing plate comprising a. delete delete

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