TWI752914B - Surface protection film for polarizing plate, polarizing plate, and manufacturing method of polarizing plate - Google Patents

Abstract

The present invention provides a surface protection film for a polarizing plate capable of enhancing shear force and reducing dynamic friction force, while achieving both curl controllability and smoothness.

The surface protective film for polarizing plates of the present invention is characterized in that it is a surface protective film for polarizing plates having an adhesive layer formed of an adhesive composition on one or both surfaces of a support film, and the adhesive composition contains (methyl) ) An acrylic polymer and a silicone compound represented by the following formula, wherein the (meth)acrylic polymer contains at least a (meth)acrylic monomer 50 to 50 having an alkyl group having 1 to 14 carbon atoms. 99.9% by mass as a monomer component, with respect to 100 parts by mass of the (meth)acrylic polymer, 0.01 part by mass to less than 1 part by mass of the aforementioned silicone compound is contained, and the aforementioned adhesive layer is adhered with an adhesive area of 1 cm ² After being attached to the TAC polarizing plate for 30 minutes at 23°C, the shearing force during stretching at a tensile speed of 0.06mm/min in the shearing direction is 15N/ ^cm2 or more, so that the surface of the above-mentioned adhesive layer is attached. After attaching to the TAC polarizing plate for 30 minutes at 23°C, peel off the surface protective film for the polarizing plate from the TAC polarizing plate, so that the brightness enhancement film is in contact with the surface of the TAC polarizing plate pasted on the surface of the adhesive layer. , the dynamic friction force when stretched at a stretching speed of 100 mm/min in a direction parallel to the contact surface under a load of 200 g is 1 N or less.

In the formula, R and R' are methyl or phenyl, 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 protection film for polarizing plate, polarizing plate, and manufacturing method of 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 for producing a polarizing plate. Specifically, it relates to a surface protection film for a polarizing plate for protecting the surface of a polarizing plate by sticking to a polarizing plate used for a liquid crystal display. For example, the surface protection film for polarizing plates is used for the protection of polarizing plates by manufacturers of polarizing plates at the time of delivery of the polarizing plates, the manufacturers of liquid crystal displays are used for the protection of polarizing plates in the production process of display devices (liquid crystal modules), etc., and polarizing in various steps. Protective use of the board. Furthermore, the present invention relates to a polarizing plate protected by a surface protective film for a polarizing plate, and also relates to a method for producing a silicone compound transfer type polarizing plate in which a silicone compound is transferred to the surface of the polarizing plate.

Background technique

When transporting or mounting optical components/electronic components on a printed circuit board, each component is transported in a state in which it is packaged in a predetermined sheet and in a state where an adhesive tape is attached. Among them, surface protection films are widely used in the field of optical/electronic parts in particular.

The surface protection film is usually bonded to the adherend through an adhesive applied to the side of the support film, and is used for the purpose of preventing damage and contamination of the adherend during processing and transportation (Patent Document 1). For example, liquid crystal display A display (LCD) panel is formed by bonding optical members, such as a polarizing plate and a wavelength plate, to a liquid crystal cell through an adhesive. These optical members, such as polarizing plates, are bonded with a surface protective film through an adhesive to prevent damage and contamination during processing and transportation.

In recent years, polarizing plates used for LCD panels have been thinned along with the thinning of LCD panels. Therefore, when assembling the LCD panel, the distance (interval) between the brightness enhancement film and the polarizing plate is also reduced. As the thickness becomes thinner, the thinned LCD panel or the polarizer is bent, and the brightness enhancement film is in contact with the polarizer, causing problems such as damage to the polarizer.

In addition, in order to prevent unnecessary curling and unwanted curling (the so-called curling refers to a phenomenon of warping, for example, a flat plate-shaped object is warped to one side of any surface as a whole) in the polarizing plate itself. A phenomenon in which a flat object is warped in a wavy shape as a whole, etc.), and curl adjustability is required. When unnecessary curling or unwanted curling occurs, handleability deteriorates, for example, when a polarizing plate or the like is attached to a liquid crystal cell, problems such as trapping of air bubbles may occur.

On the other hand, by mixing polyether-modified silicone that acts as an antistatic agent in the adhesive layer of the surface protection film, the polyether-modified silicone is transferred to the surface of the adherend (for example, polarizing plate) in a small amount, Thereby, antistatic properties can be imparted to the adherend, and when the adherend is in contact with a member, the dynamic friction force of the adherend can be reduced, the smoothness can be improved, and the occurrence of damage to the adherend can be suppressed. On the other hand, due to the presence of a small amount of polyether-modified silicone transferred to the surface of the adherend, the shear force of the adherend is reduced, and the problem of deteriorating the curl controllability of the adherend occurs.

prior art literature Patent Literature

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

Summary of Invention

Therefore, an object of the present invention is to provide a surface protective film for polarizing plates, which can enhance the shear force of the adhesive layer and reduce the amount of adhesive After the surface protection film is peeled off, the dynamic friction force of the polarizing plate of the adherend is aimed at both the curl controllability of the polarizing plate and the smoothness of the polarizing plate.

That is, the surface protective film for polarizing plates of the present invention is characterized in that it is a surface protective film for polarizing plates having an adhesive layer formed of an adhesive composition on one or both surfaces of a support film, and the adhesive composition contains ( A meth)acrylic polymer and a silicone compound represented by the following formula, wherein the (meth)acrylic polymer contains at least a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms 50 to 99.9% by mass as a monomer component, relative to 100 parts by mass of the (meth)acrylic polymer, containing 0.01 part by mass to less than 1 part by mass of the aforementioned silicone compound, so that the aforementioned adhesive layer is adhered at a thickness of 1 cm ² The area is attached to the TAC polarizing plate, and after sticking at 23 ° C for 30 minutes, the shear force when stretching is carried out at a tensile speed of 0.06 mm/min in the shearing direction is 15 N/cm ² or more, so that the aforementioned adhesive layer is The surface is attached to the TAC polarizing plate, and after 30 minutes of pasting at 23 ° C, the surface protective film for the polarizing plate is peeled off from the aforementioned TAC polarizing plate, so that the brightness enhancement film and the aforementioned TAC polarizing plate are pasted over the surface of the aforementioned adhesive layer. In the case of surface contact, the dynamic friction force when stretched at a stretching speed of 100 mm/min in a direction parallel to the contact surface with a load of 200 g applied was 1 N or less.

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

Regarding the surface protective film for polarizing plates of the present invention, it is preferable that the adhesive composition contains a surfactant having an alkylene oxide group.

It is preferable that the said adhesive composition contains an ionic compound about the surface protection film for polarizing plates of this invention.

As for the surface protection film for polarizing plates of this invention, it is preferable that the said (meth)acrylic-type polymer contains the (meth)acrylic-type monomer which has a hydroxyl group as a monomer component.

As for the surface protection film for polarizing plates of this invention, it is preferable that the said (meth)acrylic-type polymer contains the (meth)acrylic-type monomer which has a carboxyl group as a monomer component.

The polarizing plate of the present invention is preferably protected by the above-mentioned surface protective film for polarizing plates.

The manufacturing method of the silicone compound transfer type polarizing plate of the present invention It preferably includes: the step of making the surface of the adhesive layer of the surface protection film for the polarizer adhere to the surface of the polarizer; and peeling off the surface protection film for the polarizer from the surface of the polarizer, so as to remove the surface protection film The step of transferring the silicone compound contained in the adhesive layer to the surface of the polarizing plate.

Since the surface protective film for polarizing plates of the present invention can improve shear force, when the surface protective film for polarizing plates is bonded to a thinned polarizing plate, the occurrence of curling of the polarizing plate can be suppressed and curling can be obtained It is useful as a polarizing plate excellent in adjustability. In addition, when the liquid crystal display panel is assembled after sticking and peeling the surface protective film for a polarizing plate of the present invention on a polarizing plate, the dynamic friction force of the polarizing plate can be reduced even when the polarizing plate is in contact with a brightness enhancement film or the like. Since the suppression is low, the polarizing plate is less likely to be damaged, and it is useful because of its excellent smoothness.

1: Surface protection film for polarizer (surface protection film)

2: polarizer

3: Adhesive layer

4: Support film

5: Polarizing plate (polarizing plate) with surface protection film for polarizing plate attached

10: Acrylic Sheet

20: TAC polarizer

30: Sample fixing table

40: Potentiometer

1 is a schematic cross-sectional view of a polarizing plate with a surface protective film for a polarizing plate according to a preferred embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a method of measuring the peeling charge voltage.

Form for carrying out the invention

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

<Overall structure of the surface protective film (surface protective film) for polarizing plates>

The surface protective film for polarizing plates of the present invention (hereinafter, may be simply referred to as "surface protection film") Surface protective film") is usually called a surface protective film, adhesive tape, adhesive label, adhesive film, etc., especially suitable for use in optical parts (for example, polarizers, wave plates, etc.) as liquid crystal display panel components. A surface protection film that protects the surface of optical parts during processing and transportation of optical parts used. Although the adhesive layer of the surface protection film is usually formed continuously, it is not limited to such a method. For example, it is also possible to It is an adhesive layer which forms regular or random patterns such as dots, stripes, etc. In addition, the surface protection film disclosed here may be in a roll shape or a sheet shape.

As a typical structural example of the surface protective film (surface protective film) for polarizing plates disclosed here, a surface protective film having an adhesive layer on one or both surfaces of a support film (substrate), a surface protective film provided on a support film The antistatic layer on one side of the film and the surface protection film of the adhesive layer provided on the surface of the support film on the opposite side of the antistatic layer. The surface protective film is used by adhering the adhesive layer to the adherend (polarizing plate to be protected). The surface protective film before use (that is, before sticking to the adherend) may be a form in which the surface of the adhesive layer (the surface to be adhered to the adherend) is protected by a release liner with at least the side of the pressure-sensitive adhesive layer being the release surface . Alternatively, the surface protection film may be wound in a roll shape, and the adhesive layer may be in contact with the back surface (surface of the antistatic layer) of the support film to protect the surface.

<Support Film>

The surface protective film (surface protective film) for polarizing plates of the present invention is characterized by having a support film formed of an adhesive composition on one or both surfaces of the support film. adhesive layer. Although the resin material constituting the support film can be used without particular limitation, for example, a resin material excellent in properties such as transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, flexibility, and dimensional stability is preferably used. Material. In particular, since the support film has flexibility, the adhesive composition can be applied by a roll coater or the like, and it can be wound into a roll shape, which is useful.

As the support film (substrate), for example, a plastic film can be preferably used as the support film, wherein the plastic film is made of polyethylene terephthalate (PET), polyethylene naphthalate Polyester-based polymers such as alcohol esters (PEN) and polybutylene terephthalate; cellulose-based polymers such as cellulose diacetate and cellulose triacetate; polycarbonate-based polymers; polymethyl methacrylate Acrylic polymers such as esters are composed of a resin material whose main resin component (the main component in the resin component, usually accounts for 50% by mass or more) of the resin material. Other examples of the resin material include styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymer; polyethylene, polypropylene, polyolefins having cyclic or norbornene structures, ethylene - Olefin-based polymers such as propylene copolymers; vinyl chloride-based polymers; amide-based polymers such as nylon 6, nylon 6,6, and aromatic polyamides are examples of resin materials. Further, as other examples of the resin material, amide-imide-based polymers, silo-based polymers, polyether s-series polymers, polyether ether ketone-based polymers, polyphenylene sulfide-based polymers, Vinyl alcohol-based polymers, vinylidene chloride-based polymers, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, and the like. A support film composed of a mixture of two or more of the above polymers may be used.

As the support film, a plastic film made of a transparent thermoplastic resin material can be preferably used. Among the plastic films, a polyester film is preferably used. Here, the term "polyester film" refers to a film containing a polymer material (polyester resin) as a main resin component, wherein the polymer material has polyethylene terephthalate (PET), polyethylene naphthalate Main skeleton based on ester bonds of ethylene formate (PEN) and polybutylene terephthalate. Such a polyester film has preferable properties such as excellent optical properties and dimensional stability as a support film for a surface protective film, and on the other hand, it has the property of being easily charged.

If necessary, various additives such as antioxidants, ultraviolet absorbers, plasticizers, colorants (pigments, dyes, etc.) may be blended with the resin material constituting the support film. Known or conventional methods such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, primer coating, etc. surface treatment. Such surface treatment may be, for example, treatment for improving the adhesion between the support film and the adhesive layer (anchoring property of the adhesive layer). A surface treatment such that polar groups such as hydroxyl groups are introduced into the surface of the support film can be preferably used.

In addition, although the surface protection film of the present invention can also have an antistatic layer on the side opposite to the adhesive layer of the supporting film, in the case of having an antistatic function, an antistatically treated plastic film can also be used as the protective film. the support film. The use of the support film is preferable because the electrification of the surface protection film itself at the time of peeling can be suppressed. In addition, the support film is a plastic film, and the antistatic treatment is performed on the plastic film. To reduce the charging of the surface protection film itself, and to obtain a plastic film with excellent antistatic function to the adherend. It should be noted that the method for imparting an antistatic function is not particularly limited, and conventionally known methods can be used, for example, coating an antistatic resin, a conductive polymer, a conductive A method of using a conductive resin of a conductive material, a method of vapor deposition or electroplating of a conductive material, or a method of mixing an antistatic agent or the like.

As a thickness of the said support film, it is 1-200 micrometers normally, Preferably it is about 5-100 micrometers. When the thickness of the support film is within the above-mentioned range, it is preferable since it is excellent in the workability of bonding to the polarizing plate as the adherend and the workability of peeling from the adherend.

<Adhesive composition>

The surface protective film (surface protective film) for polarizing plates of the present invention has the adhesive layer, and the adhesive layer is an adhesive layer formed of an adhesive composition, and the adhesive composition contains ( based) adhesive compositions of acrylic polymers.

The adhesive composition used in the present invention contains a (meth)acrylic polymer containing at least a (meth)acrylic polymer having an alkyl group having 1 to 14 carbon atoms. 50 to 99.9% by mass of the monomer is not particularly limited as long as it is an adhesive (meth)acrylic polymer as a monomer component, but a (methyl) polymer having an alkyl group having 1 to 14 carbon atoms is used. ) acrylic monomer The (meth)acrylic polymer which is a monomer component is preferably a (meth)acrylic monomer having an alkyl group having 4 to 14 carbon atoms. As the (meth)acrylic-based monomer, one or two types of monomers may be used. as the main component. In addition, the (meth)acrylic polymer of the present invention refers to an acrylic polymer and/or a methacrylic polymer, and the (meth)acrylate refers to acrylate and/or methyl based acrylate. In addition, the so-called main component means the component which is compounded most among the components.

The surface protective film of the present invention contains the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms in an amount of 50 to 99.9 mass %, preferably 60 to 99 mass %, more preferably 70 to 98 mass %, and most preferably 80 to 97 mass %. Since the adhesive composition has moderate wettability and is excellent in the cohesive force of the adhesive (layer) by being within the above-mentioned range, it is preferable.

Specific examples of the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylate. n-butyl acrylate, 2-butyl (meth)acrylate, 3-butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, 2-ethyl (meth)acrylate Hexyl (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, and the like.

Among them, when used as the surface protection film of the present invention, preferred (meth)acrylic monomers include hexyl (meth)acrylate and 2-ethylhexyl (meth)acrylate. , n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, (meth) Isodecyl acrylate, (meth)propylene (Meth)acrylates having an alkyl group having 6 to 14 carbon atoms, such as n-dodecyl enoate, n-tridecyl (meth)acrylate, and n-tetradecyl (meth)acrylate . By using the (meth)acrylate having an alkyl group having 6 to 14 carbon atoms, it is easy to control the adhesive force to the adherend to be low, and it becomes a surface protection film excellent in releasability.

As for the surface protection film of this invention, it is preferable that the said (meth)acrylic-type polymer contains the (meth)acrylic-type monomer which has a hydroxyl group as a monomer component. Since the above-mentioned hydroxyl group can easily control the crosslinking, it is a preferable form. In addition, the shear force of the adhesive (layer) can be increased, and by bonding the adhesive to the adherend, curling by the adherend can be suppressed, and the gap between the adhesive and the adherend (interface) can be suppressed. Sliding, offset generation, so it is better.

In addition, by using the (meth)acrylic monomer having the hydroxyl group as a monomer component in the (meth)acrylic polymer, it becomes easy to control the crosslinking of the adhesive composition and the like, and it becomes easy to Control the improvement of wettability caused by flow and the balance of cohesion and shear force of the adhesive (layer). Furthermore, when an antistatic agent is added to the binder, generally, unlike a carboxyl group, a sulfonate group, etc. that can function as a crosslinking site, the hydroxyl group has a moderate interaction with an ionic compound and the like as an antistatic agent. Therefore, it is preferable to use it even from the viewpoint of antistatic properties.

The surface protective film of the present invention preferably contains 0.1 to 20 mass % of a (meth)acrylic monomer having a hydroxyl group, more preferably 1, with respect to the total amount of the monomer components constituting the (meth)acrylic polymer. -15 mass %, More preferably, it is 2-12 mass %. When within the stated range, due to easy control The wettability of the adhesive composition and the balance of the cohesive force and shear force of the adhesive (layer) are therefore preferred.

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

In the surface protective film of the present invention, the (meth)acrylic polymer preferably contains a (meth)acrylic monomer having a carboxyl group as a monomer component. Since the carboxyl group can increase the shear force or prevent the increase of the adhesive force over time, it is a preferable aspect. In particular, since the shear force of the adhesive (layer) is increased, by attaching the adhesive to the adherend, curling due to the adherend can be suppressed, and the gap between the adhesive and the adherend can be suppressed. It is preferable because of slippage of interface) and generation of deviation.

In addition, by using the (meth)acrylic monomer having a carboxyl group as a monomer component in the (meth)acrylic polymer, the time-dependent adhesive force of the surface protective film (adhesive layer) can be suppressed. Reinforcement is preferred because it is excellent in re-peelability, inhibition of adhesive force enhancement, and handleability, and also in cohesive force and shear force of the adhesive layer.

The surface protective film of the present invention preferably contains less than 2 mass % of the (meth)acrylic monomer having a carboxyl group, more preferably 0.001, based on the total amount of the monomer components constituting the (meth)acrylic polymer. ~1.5 mass %, more preferably 0.005 to 1 mass %, and most preferably 0.01 to 0.5 mass %. when In the range described above, the increase in adhesive strength over time can be suppressed, and the re-peelability, the adhesive strength enhancement inhibition property, and the handleability are excellent. Moreover, since the cohesion force and shearing force of an adhesive bond layer are also excellent, it is preferable. It should be noted that when there are a large number of acid functional groups such as carboxyl groups having a large polar effect, when an ionic compound is compounded as an antistatic agent, ion conduction is hindered by the interaction of the acid functional group such as a carboxyl group with the ionic compound. There is a possibility that sufficient antistatic property cannot be obtained because the electrical conductivity efficiency is lowered, so it is not desired.

Examples of the (meth)acrylic-based monomer having the carboxyl group include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and 2-(meth)propylene. Ethyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethylphthalic acid, 2- (Meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acrylonitrile Oxyethyltetrahydrophthalic acid, etc.

In addition, as other polymerizable monomer components, the glass transition temperature (Tg) is set to 0°C or lower (usually -100°C or higher) in a range that does not impair the effects of the present invention, from the viewpoint of easily achieving a balance of adhesive properties. Inside, a polymerizable monomer for adjusting the glass transition temperature and releasability of the (meth)acrylic polymer can be used.

In addition to the (meth)acrylic monomer having a hydroxyl group, the (meth)acrylic monomer having a carboxyl group, and the (meth)acrylic monomer having 1 to 14 carbon atoms used as the (meth)acrylic polymer Other polymerizable monomers other than the alkyl-based (meth)acrylic monomer can be used without particular limitations as long as they are within a range that does not impair the properties of the present invention. For example, it can be When using cohesion/heat resistance improving components such as cyano group-containing monomers, vinyl ester monomers, and aromatic vinyl monomers, amide group-containing monomers, amide group-containing monomers, amine group-containing monomers, etc. A monomer, an epoxy group-containing monomer, an N-acrylomorpholine, a vinyl ether monomer, and the like, a component having a functional group that improves adhesion (adhesion) or functions as a crosslinking base point. These polymerizable monomers may be used alone or in combination of two or more.

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

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

As said aromatic vinyl monomer, styrene, chlorostyrene, chloromethylstyrene, alpha-methylstyrene, other substituted styrene etc. are mentioned, for example.

Examples of the amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N,N-dimethylacrylamide, N,N-dimethylacrylamide, N-vinylpyrrolidone , N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N,N'-methylenebisacrylamide, N , N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylate, diacetone acrylamide, etc.

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

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

As said epoxy group-containing monomer, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, allyl glycidyl ether, etc. are mentioned, for example.

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

In the present invention, in addition to the (meth)acrylic monomer having a carboxyl group, the (meth)acrylic monomer having a hydroxyl group, and the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms In the total amount of monomer components (total monomer components) constituting the (meth)acrylic polymer, other polymerizable monomers other than monomers are preferably 0 to 40% by mass, more preferably 0 to 30% by mass. quality%. By using the other polymerizable monomer 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 adjusted.

The weight average molecular weight of the (meth)acrylic polymer is 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, since the cohesion force of the obtained adhesive agent (layer) becomes small, there exists a tendency for adhesive residue to generate|occur|produce. On the other hand, when the weight average molecular weight exceeds 5,000,000, the fluidity of the polymer decreases, the wetting of the adherend (polarizing plate) is insufficient, and the adhesive composition becomes the adherend and the surface protective film. The tendency to cause blistering between layers. In addition, the weight average molecular weight means the value measured by GPC (gel permeation chromatography).

In addition, the glass transition of the (meth)acrylic polymer The temperature (Tg) is preferably 0°C or lower, more preferably -10°C or lower, still more preferably -20°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 wetting of the adherend (polarizing plate) is insufficient, and there is an adhesive composition layer that serves as a protective film between the adherend and the surface. The trend among the causes of blistering. In particular, by setting the glass transition temperature to be -61° C. or lower, an adhesive composition excellent in wettability to an adherend and light releasability can be easily obtained. In addition, the glass transition temperature of a (meth)acrylic-type polymer can be adjusted within the said range by suitably changing the monomer component and composition ratio used.

The polymerization method of the (meth)acrylic polymer used in the present invention is not particularly limited, and the polymerization can be carried out by known methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. . Considering the characteristics of low pollution of the adhered body (polarizing plate), a better method is solution polymerization. In addition, the obtained polymer may be any of a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer, and the like.

<Silicone compound>

The surface protection film of the present invention is characterized in that the adhesive composition contains a silicone compound represented by the following formula. Although the detailed reason is not clear, by using the above-mentioned silicone compound, since the molecular skeleton does not contain an ether group, the elastic modulus of the obtained adhesive (layer) can be suppressed from being lowered, and the cohesion force is not caused. and shear force reduction, so when the surface protection film is bonded to the thinned polarizing plate, the polarizing plate can be suppressed from being damaged. The occurrence of curl can obtain a polarizing plate excellent in curl controllability.

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

Moreover, as a specific example of the commercial item of the said silicone compound preparation, KF-50-100cs (methyl phenyl silicone oil), KF-50-300cs (methyl phenyl silicone oil), KF-50- 1000cs (methyl phenyl silicone oil), KF-50-3000cs (methyl phenyl silicone oil), KF-53 (methyl phenyl silicone oil), KF-54 (methyl phenyl silicone oil), KF-96-100cs ( Dimethyl silicone oil), KF-96-300cs (methyl phenyl silicone oil), KF-96-1000cs (dimethyl silicone oil), KF-96-3000cs (dimethyl silicone oil), KF-96-10,000 cs (Dimethicone) (manufactured by Shin-Etsu Chemical Co., Ltd.), etc.

The adhesive composition of the surface protection film of the present invention contains 0.01 to less than 1 part by mass of the silicone compound, preferably 0.02 to 100 parts by mass of the (meth)acrylic polymer. 0.98 parts by mass, more preferably 0.03 to 0.96 parts by mass. Within the above range, coexistence of shear force and dynamic friction force can be achieved, and low contamination properties are excellent, which is preferable.

<Surfactant having an alkylene oxide group>

Regarding the surface protection film of the present invention, it is preferable that the adhesive composition contains a surfactant having an alkylene oxide group. By including a surfactant having an alkylene oxide group in the adhesive composition, it is possible to further obtain It is useful as an adhesive layer excellent in wettability to a polarizing plate as an adherend.

Specific examples of the surfactant having an alkyleneoxy group include polyoxyalkylene alkylamines, polyoxyalkylene diamines, polyoxyalkylene fatty acid esters, and polyoxyalkylene sorbitan fatty acid esters, for example. , polyoxyalkylene alkyl phenyl ether, polyoxyalkylene alkyl ether, polyoxyalkylene alkyl allyl ether, polyoxyalkylene alkyl phenyl allyl ether and other nonionic surfactants; polyoxyalkylene alkyl Anionic surfactants, such as base ether sulfate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether sulfate, polyoxyalkylene alkyl phenyl ether phosphate, etc.; A cationic surfactant, a zionic surfactant, etc. of an oxyalkylene chain (polyalkenyl oxide chain). Moreover, the surfactant which has the said alkylene oxide group may be used individually and may be used in combination of 2 or more types.

As a preferred embodiment, the above-mentioned surfactant having an alkylene oxide group is a compound having at least a part of a (poly)vinyl oxide chain. When an antistatic agent is blended by blending a compound having the above-mentioned (poly)vinyl oxide chain in addition to the base polymer, the compatibility with the antistatic agent is improved, and the tendency to act as an adherend is appropriately suppressed. The exudation of the polarizing plate can be obtained, and the adhesive composition with low pollution can be obtained. As the compound having the above-mentioned (poly)vinyl oxide chain, the mass of the (poly)vinyl oxide chain contained in the entire compound is preferably 5 to 90% by mass, more preferably 5 to 85% by mass, More preferably, it is 5 to 80 mass %, and most preferably, it is 5 to 75 mass %.

The number average molecular weight (Mn) of the surfactant having an alkylene oxide group is preferably a number average molecular weight of 50,000 or less, more preferably 200-30,000, more preferably 200-10,000, particularly preferably 200-5,000 number average molecular weight. When the number average molecular weight is too large compared to 50,000, the compatibility with the acrylic polymer decreases, and the adhesive layer tends to be whitened. When the number average molecular weight is too small compared to 200, contamination by the polyoxyalkylene compound may easily occur. In addition, the number average molecular weight here means the polystyrene conversion value obtained by GPC (gel permeation chromatography).

In addition, as a specific example of the commercial item of the surfactant which has the said alkylene oxide group, Aqualon KH-10, Aqualon HS-10, Noigen EA-137, Hitenol NF-08 (made by Daiichi Kogyo Co., Ltd.) are mentioned, for example. ), Latemul PD-420 (made by Kao Corporation), etc.

The content of the surfactant having an alkylene oxide group can be, for example, 0 to 5 parts by mass, preferably 0.01 to 2 parts by mass, relative to 100 parts by mass of the (meth)acrylic polymer, and more preferably 0.01 to 2 parts by mass. Preferably it is 0.05-1 mass part. When the antistatic agent is blended within the above range, the effect of preventing bleeding of the antistatic agent can be obtained, which is preferable.

Moreover, an acrylic oligomer may be contained in the said adhesive composition. The weight average molecular weight (Mw) of the acrylic oligomer is preferably 1,000 or more and less than 30,000, more preferably 1,500 or more and less than 20,000, and still more preferably 2,000 or more and less than 10,000. In the case of the acrylic pressure-sensitive adhesive composition used for the surface protection application (for re-peeling) of the present embodiment, it functions as a tackifier resin, improves adhesion (adhesion), and suppresses the lifting of the surface protection film. Effect.

(Meth)acrylic acid can be used in the acrylic oligomer Ester monomers, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, ( Isobutyl meth)acrylate, second butyl (meth)acrylate, 3rd butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, (meth)acrylic acid Hexyl ester, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, ( Isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (meth) (meth)acrylic acid alkyl ester; (meth)acrylic acid phenyl ester, (meth)acrylic acid aryl (meth)acrylic acid ester such as benzyl ester; (meth)acrylic acid ester obtained from terpene compound derivative alcohol, etc.

In addition, a (meth)acrylic monomer having an alicyclic structure can be used for the acrylic oligomer, and examples thereof include dicyclopentyl methacrylate, dicyclopentyl acrylate, and bicyclo methacrylate. Amyloxyethyl, dicyclopentyloxyethyl acrylate, tricyclopentyl methacrylate, tricyclopentyl acrylate, 1-adamantyl methacrylate, 1-adamantyl acrylate, 2 -Methyl-2-adamantyl methacrylate, 2-methyl-2-adamantyl acrylate, 2-ethyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl (meth)acrylates such as alkyl acrylates and the like. Such (meth)acrylic monomers can be used alone or in combination of two or more.

In addition to the (meth)acrylic monomer component unit, the acrylic oligomer may contain the (meth)acrylic monomer and another monomer component (copolymerizable monomer) that can be copolymerized. ) are obtained by copolymerization.

The weight average molecular weight (Mw) of the acrylic oligomer is 1,000 or more and less than 30,000, preferably 1,500 or more and less than 20,000, and still more preferably 2,000 or more and less than 10,000. When the weight average molecular weight is 30,000 or more, the adhesiveness (adhesion) decreases. In addition, when the weight average molecular weight is less than 1000, since the molecular weight is low, the adhesive force of the surface protection film is lowered.

Regarding the surface protection film of the present invention, preferably, the adhesive composition does not contain an organopolysiloxane having a polyoxyalkylene chain. Although the use of the organopolysiloxane can reduce the peeling of the surface protective film (adhesive layer) and the dynamic friction force of the polarizing plate can be reduced, on the other hand, the shear force is reduced, So it becomes the undesired way. It should be noted that although the detailed reason for the decrease in shear force is not clear, it is presumed to be the following reason: Since the skeleton contains a silicone component in addition to the ether group, the elastic modulus of the obtained adhesive (layer) becomes lower, resulting in a decrease in cohesion and a decrease in shear force.

<Antistatic agent>

The adhesive composition of the surface protection film of the present invention may contain an antistatic agent (antistatic component), and may contain an ionic compound as the antistatic agent. Examples of the ionic compound include alkali metal salts and/or ionic compounds (ionic liquids, etc.) having a low melting point (melting point of 150° C. or lower). By containing these ionic compounds, excellent antistatic properties can be imparted.

In addition, the content of the antistatic agent is preferably 1 part by mass or less, more preferably 0.001 to 0.9 parts by mass, and still more preferably 0.005 to 0.8 parts by mass relative to 100 parts by mass of the (meth)acrylic polymer. share. when in Within the above range, since it is easy to achieve both antistatic properties and low contamination properties, it is preferable.

<Crosslinking agent>

Regarding the surface protection film of the present invention, it is preferable that the adhesive composition contains a crosslinking agent. Furthermore, in the present invention, the adhesive composition is used as an adhesive layer. For example, in the case where the adhesive composition contains the (meth)acrylic polymer, the constituent units, constituent ratios, and crosslinking agents of the (meth)acrylic polymer are appropriately adjusted. It is possible to obtain a surface protective film (adhesive layer) with more excellent heat resistance by selecting and adding ratios and the like for crosslinking.

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

Examples of the isocyanate compound include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI), dimer acid diisocyanate, cyclopentylene diisocyanate, Alicyclic isocyanates such as cyclohexylene diisocyanate and isophorone diisocyanate (IPDI), 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate (XDI ) and other aromatic isocyanates, the isocyanate compounds are linked by an allophanate bond, biuret bond, isocyanurate bond, uretdione bond, urea bond, carbodiimide bond, uretonidene bond amine bond, oxadiazine trione bond, etc. modified polyisocyanide Ester modification. For example, commercial products include Takenate 300S, Takenate 500, Takenate D165N, Takenate D178N (the above are manufactured by Mitsui Chemicals Co., Ltd.), Sumidur T80, Sumidur L, Desmodur N3400 (the above are manufactured by Sumidur Bayer Polyurethane Co., Ltd.) , Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (the above are manufactured by Japan Polyurethane Industry Co., Ltd.), etc. These isocyanate compounds may be used alone, two or more types may be mixed and used, and a bifunctional isocyanate compound and a trifunctional or more functional isocyanate compound may be used in combination. By using a crosslinking agent in combination, both adhesion and rebound resistance (adhesion to a curved surface) can be achieved, and a surface protection film (adhesive layer) with 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.), 1,3-bis (N,N-diglycidylaminomethyl)cyclohexane (trade name TETRAD-C, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and the like.

As said melamine-type resin, hexamethylol melamine etc. are mentioned. As an aziridine derivative, the trade name HDU, TAZM, and TAZO (the above are made by Mutual Pharmaceutical Co., Ltd.), which are commercially available products, can be mentioned, for example.

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

The content of the crosslinking agent used in the present invention is, for example, preferably 0.01 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, and still more preferably 1 part by mass relative to 100 parts by mass of the (meth)acrylic polymer. ~5 parts by mass. In the case where the content is less than 0.01 part by mass, cross-linking caused by the cross-linking agent Insufficient link formation, the cohesive force of the obtained adhesive bond layer is small, sufficient heat resistance may not be obtained, and there is a tendency that it becomes a cause of adhesive residue. On the other hand, when the content exceeds 10 parts by mass, the cohesive force of the polymer is large, the fluidity is lowered, the wetting of the adherend (polarizing plate) is insufficient, and the adherend and the adhesive layer (adhesion) are caused. The tendency of the cause of foaming between the agent composition layers). Furthermore, when the amount of crosslinking is large, there is a tendency that the peel charging characteristics are lowered. In addition, these crosslinking agents may be used alone or in combination of two or more.

In order to make any of the above-mentioned cross-linking reactions proceed more efficiently, the adhesive composition may further contain a cross-linking catalyst. As such a crosslinking catalyst, for example, tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris(acetylacetone)iron, tris(hexane-2,4-dione)iron, Tris(heptane-2,4-dione)iron, Tris(heptane-3,5-dione)iron, Tris(5-methylhexane-2,4-dione)iron, Tris(octane) -2,4-dione)iron, tris(6-methylheptane-2,4-dione)iron, tris(2,6-dimethylheptane-3,5-dione)iron, tris(2,6-dimethylheptane-3,5-dione)iron (nonane-2,4-dione)iron, tris(nonane-4,6-dione)iron, tris(2,2,6,6-tetramethylheptane-3,5-dione) Iron, Tris(tridecane-6,8-dione)iron, Tris(1-phenylbutane-1,3-dione)iron, Tris(hexafluoroacetone acetone)iron, Tris(acetylacetate) ethyl)iron, tris(acetonitrile-n-propylacetate)iron, tris(acetonitrile-isopropylacetate)iron, tris(acetonitrile-n-butylacetate)iron, tris(2-butylacetate)iron, Tris(3-butylacetate)iron, tris(methylpropylacetate)iron, tris(ethylacetate)iron, tris(n-propylacetate)iron, isopropyl tris(propylacetate) ester) iron, tris(propylacetate-n-butyl acetate)iron, tris(2-butylpropylacetate)iron, tris(tertiary butylacetate)iron, tris(acetoxybenzyl acetate)iron, tris(2-butylacetate)iron (dimethylmalonate)iron, tris(diethylmalonate)iron, tris(diethylmalonate)iron Iron-based catalysts such as iron methoxy, iron triethoxide, iron triisopropoxide, and iron chloride. 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, it is preferably about 0.0001 to 1 part by mass, and more preferably about 0.001 to 0.5 part by mass with respect to 100 parts by mass of the (meth)acrylic polymer. When it is in the said range, the rate of the crosslinking reaction when forming an adhesive bond layer becomes high, and the pot life of an adhesive composition becomes long, and it becomes a preferable form.

Furthermore, the adhesive composition may contain a compound that produces keto-enol tautomerism as a crosslinking retarder. For example, in an adhesive composition containing a cross-linking agent or an adhesive composition obtained by blending a cross-linking agent, an aspect that contains the compound that produces the keto-enol tautomerism can be preferably used. Thereby, excessive viscosity increase and gelation of the adhesive composition after blending of the crosslinking agent can be suppressed, and the effect of prolonging the pot life of the adhesive composition can be achieved. In the case of using at least an isocyanate compound as the crosslinking agent, it is of particular interest to contain a compound which produces keto-enol tautomerism. This technique can be preferably applied, for example, when the adhesive composition is in the form of an organic solvent solution or a solvent-free form.

As the compound that produces the keto-enol tautomerism, various β-dicarbonyl compounds can be used. Specific examples include acetone acetone, 2,4-hexanedione, 3,5-heptanedione, 2-methylhexane-3,5-dione, 6-methylheptane-2, β-diketones such as 4-diketone, 2,6-dimethylheptane-3,5-dione, etc.; Acetyl acetate such as tert-butyl acetate; propyl acetate such as methyl propyl acetate, ethyl propyl acetate, isopropyl propyl acetate, tert-butyl propyl acetate, etc.; Isobutyryl acetate, methyl isobutyrate, ethyl isobutyrate, isopropyl isobutyrate, tert-butyl isobutyrate, etc.; methyl malonate, ethyl malonate, etc. Malonates, etc. Among them, acetylacetone and acetylacetate are mentioned as preferable compounds. Such a compound that produces keto-enol tautomerism may be used alone or in combination of two or more.

The content of the compound that produces keto-enol tautomerism relative to 100 parts by mass of the (meth)acrylic polymer can be, for example, 0.1 to 20 parts by mass, usually 0.5 to 15 parts by mass (for example, 0.5 to 15 parts by mass). 1 to 10 parts by mass) is suitable. When the amount of the compound is too small, it may be difficult to exhibit a sufficient use effect. On the other hand, when the said compound is used excessively more than necessary, it may remain|survive in an adhesive bond layer, and cohesion force may fall.

Further, the adhesive composition used for the surface protective film of the present invention may contain other known additives, for example, powders such as colorants, pigments, plasticizers, tackifiers, Low molecular weight polymers, surface lubricants, leveling agents, antioxidants, preservatives, light stabilizers, UV absorbers, polymerization inhibitors, silane coupling agents, inorganic or organic fillers, metal powders, particles or foils objects, etc.

The surface protection film of the present invention is characterized by having an adhesive layer formed of the adhesive composition (formed by crosslinking the adhesive composition) on one or both surfaces of the support film. Although the crosslinking of the adhesive composition is usually performed after the application of the adhesive composition, the adhesive layer formed of the crosslinked adhesive composition may be transferred to a support film or the like. In addition, although the method of forming the adhesive layer on the support film is not particularly important, for example, the adhesive composition can be coated on The support film is dried to remove the polymerization solvent, etc., thereby forming an adhesive layer on the support film to manufacture. After that, curing may be performed in order to adjust the component transfer of the adhesive layer, adjust the crosslinking reaction, and the like. In addition, when applying the adhesive composition on the support film to produce a surface protection film, one or more solvents other than the polymerization solvent may be newly added to the adhesive composition in order to allow the adhesive composition to be uniformly coated on the support film.

Moreover, as the formation method of the adhesive bond layer at the time of manufacture of the surface protection film of this invention, the well-known method used for manufacture of an adhesive sheet (surface protection film) can be used. Specifically, for example, roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating method, extrusion coating method using a die coater, etc. are mentioned.

Generally, the thickness of the said adhesive bond layer of the surface protection film of this invention is preferably made 3-100 micrometers, More preferably, it is about 5-50 micrometers. When the thickness of the pressure-sensitive adhesive layer is within the above-mentioned range, it is easy to obtain a balance between moderate re-peelability and adhesion (adhesion), which is preferable.

<Spacer>

In the surface protection film of the present invention, if necessary, for the purpose of protecting the adhesive surface of the pressure-sensitive adhesive layer, a separator may be bonded to the surface of the pressure-sensitive adhesive layer.

Although there are paper and a plastic film as a material constituting the spacer, a plastic film is preferably used from the viewpoint of excellent surface smoothness. The film is not particularly limited as long as it can protect the adhesive layer, and examples thereof include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, PVC film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene terephthalate Butylene formate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.

The thickness of the separator is usually 5-200 μm, preferably about 10-100 μm. It is preferable that it is in the said range, since the lamination workability|operativity with respect to an adhesive bond layer and the peeling workability from an adhesive bond layer are excellent. If necessary, the separator may be subjected to mold release and antifouling treatment by a silicone-based, fluorine-based, long-chain alkane-based or fatty acid amide-based mold release agent, silica powder, or the like, or a coating type. , mixed type, evaporation type and other antistatic treatment.

The surface protective film of this invention can also be implemented and obtained by carrying out the form containing other layers, such as an antistatic layer, in addition to a support film (substrate) and an adhesive bond layer.

<Polarizer>

The polarizing plate of the present invention is preferably a polarizing plate protected by the above-mentioned surface protective film for a polarizing plate (surface protective film). Since the above-mentioned surface protective film can improve the shear force, when the surface protective film for a polarizing plate is bonded to a thinned polarizing plate, it is possible to suppress the occurrence of curling of the polarizing plate, and it is possible to obtain a film having excellent curling controllability. Polarizers are therefore useful. In addition, when the liquid crystal display panel is assembled after sticking and peeling the surface protection film on the polarizing plate, the dynamic friction force of the polarizing plate can be suppressed relatively even when the polarizing plate is in contact with the brightness enhancement film or the like. Low, the polarizing plate is less likely to be damaged, and it is useful because of its excellent smoothness. It should be noted that, as shown in FIG. 1 , the polarizing plate (the polarizing plate 5 with the surface protective film) is formed by applying the adhesive layer 3 of the surface protective film 1 for the polarizing plate to the adhesive layer 3 . The surface of the polarizing plate is pasted on the surface of the polarizing plate 2 to protect the surface of the polarizing plate from damage, dust, etc.

<Manufacturing method of silicone compound transfer polarizing plate>

The manufacturing method of the silicone compound transfer type polarizing plate of the present invention preferably includes: the step of attaching the surface of the adhesive layer of the surface protection film for polarizing plate to the surface of the polarizing plate; The step of peeling off the surface protective film for polarizing plates and transferring the silicone compound contained in the adhesive layer of the surface protective film for polarizing plates to the surface of the polarizing plate. By sticking the surface of the adhesive layer to the surface of the polarizing plate, the silicone compound that does not contain ether groups segregated on the surface of the adhesive layer in the molecular skeleton is transferred to the surface of the polarizing plate, and then, Since the silicone compound remains in a small amount on the surface of the polarizing plate even if the surface protection film is peeled off, the obtained polarizing plate can suppress the dynamic friction force low even when the polarizing plate is in contact with a brightness enhancement film or the like Even if the polarizing plate itself is damaged, it is very useful because of its excellent smoothness.

As the step of sticking the surface of the adhesive layer of the surface protection film for polarizing plates to the surface of the polarizing plate, although the sticking time is not particularly limited, for example, under the conditions of 23°C and 50% RH, it is preferable to stick more than 15 minutes. As long as it is within this range, the silicone compound can be sufficiently transferred (transferred) from the surface of the adhesive to the surface of the polarizing plate, which is a preferable form.

Example

Hereinafter, although the Example etc. which show the structure and effect of this invention concretely are demonstrated, this invention is not limited to this. It should be noted, The content of compounding and characteristic evaluation of Examples and the like were measured in the following manner. In addition, in Table 1, the mixing ratio of the adhesive composition and the physical properties of the obtained (meth)acrylic polymer are shown, and in Table 2, the obtained surface protection film for polarizing plates ( surface protective film), and the results of the evaluation of the properties of the polarizing plate after the surface protective film was pasted.

<Evaluation>

Hereinafter, specific measurement/evaluation methods are described.

<Measurement of 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 mass % (THF solution)

Sample injection volume: 10μl

Eluent: THF

Flow rate: 0.6ml/min

Measurement temperature: 40℃

column:

Sample column; TSKguardcolumn SuperHZ-H (1)+TSKgel SuperHZM-H (2)

Reference column; TSKgel SuperH-RC (1 piece)

Detector: Differential Refractometer (RI)

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

<Theoretical value of glass transition temperature (Tg)>

Glass transition temperature Tg (° C.) Using the following literature value as the glass transition temperature Tgn (° C.) of the homopolymer formed from each monomer, it was calculated by the following formula have to.

Formula: 1/(Tg+273)=Σ[Wn/(Tgn+273)]

(in the formula, Tg(°C) represents the glass transition temperature of the copolymer, Wn(-) represents the mass fraction of each monomer, Tgn(°C) represents the glass transition temperature of the homopolymer formed by each monomer, n represents the type of each monomer.]

Literature value:

2-ethylhexyl acrylate (2EHA): -70°C

Acrylic (AA): 106℃

2-Hydroxyethyl acrylate (HEA): -15℃

4-Hydroxybutyl acrylate (4HBA): -32°C

In addition, the literature value refers to "synthesis/design of acrylic resin and development of new applications" (published by the Central Business Development Center Publishing Department) and "Polymer Handbook (Polymer Handbook)" (John Wiley & Sons).

<Measurement of Shear Force>

Cut the surface protective film into a size of 10 mm in width and 100 mm in length, peel off the spacer attached to the surface of the adhesive layer of the surface protective film, and take the adhesive (bonding) area of the adhesive layer of the surface protective film as 1 cm ² to make it stick to a TAC (triacetate cellulose) polarizing plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 25mm, length: 100mm), and let it stand at room temperature (23℃×50%RH) After 30 minutes, stretching was performed in the shearing direction at a stretching speed of 0.06 mm/min, and the maximum load (N/cm ² ) at this time was taken as the shearing force.

It should be noted that the shear force (N/cm ² ) is 15 or more, preferably 15-50, more preferably 20-40. As long as the shearing force is within the above range, the polarizing plate as the adherend to which the surface protection film is attached can withstand the force in the shearing direction when it is about to be curled. It is preferable because it can suppress the curling of the adherend.

<Measurement of dynamic friction force (smoothness)>

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

Next, the surface (TAC surface) of the TAC polarizing plate pasted on the surface of the adhesive layer was brought into contact with a brightness enhancement film (manufactured by Sumitomo 3M, DBEF-D2-280) as a test piece. On this test piece, a load of 200 g was applied. The load-bearing test piece was mounted on a tensile tester using a wire without stretchability, and at a measurement temperature of 25°C, the TAC surface and brightness were enhanced under the conditions of a tensile speed of 100 mm/min and a tensile distance of 50 mm. The film was stretched in the parallel direction (horizontal direction) of the contact surface, and the average value (n=3) of the dynamic friction force (N) applied to the test piece was obtained.

In addition, the said dynamic friction force (N) is 1 or less, Preferably it is 0.9 or less, More preferably, it is 0.8 or less. Within the above range, the dynamic friction force of the polarizing plate can be reduced, the damage to the surface of the polarizing plate can be suppressed, and the smoothness can be improved, which is advantageous.

<presence of damage>

The occurrence of damage on the surface of the TAC polarizing plate (TAC surface) after the dynamic friction force was measured by visual observation.

When there is no damage: ○, when there is damage: ×

<Measurement of peeling charge voltage>

Cut the surface protective film (surface protective film) for polarizing plates into a size of 70 mm in width and 130 mm in length, peel off the spacer attached to the surface of the adhesive layer of the surface protection film, and attach it to a pre-static acrylic plate (thickness). : 2mm, width: 70mm, length: 100mm) TAC polarizing plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm) surface (TAC surface), with one end protruding 30 mm by Hand pressure roller for crimping. After standing for one day at 23° C.×50% RH, as shown in FIG. 2 , the sample was set at a predetermined position. The one end portion protruding by 30 mm was fixed to an automatic winder, and peeled at a peeling angle of 150° and a peeling speed of 30 m/min. The potential (peeling charge voltage: absolute value, kV) on the surface of the polarizing plate generated at this time was measured with a potentiometer (KSD-0103, manufactured by Kasuga Electric Co., Ltd.) fixed at the center of the polarizing plate. The measurement was performed in an environment of 23°C×50%RH.

<pollution>

Cut the surface protection film into a size of 50mm in width and 80mm in length, peel off the spacer attached to the surface of the adhesive layer of the surface protection film, and paste it on a TAC polarizer cut into a width of 70mm and a length of 100mm (manufactured by Nitto Denko Co., Ltd., SEG1423DU). The polarizing plate) surface (TAC surface) was left to stand at 23° C.×50% RH for 1 day, and then the surface protective film was peeled off, and contamination was confirmed by visual inspection.

Without pollution: ○, With pollution: ×

<Preparation method>

Hereinafter, the preparation method of a specific (meth)acrylic-type polymer, an adhesive composition, etc. is described. In addition, the compounding quantity (parts) in Table 1 shows the solid content amount.

<Example 1>

<Preparation of (meth)acrylic polymer>

100 parts by mass of 2-ethylhexyl acrylate (2EHA), 10 parts by mass of 4-hydroxybutyl acrylate (4HBA), and acrylic acid (AA) were placed in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a cooler. 0.02 parts by mass, 0.2 parts by mass of 2,2'-azobisisobutyronitrile as polymerization initiators, and 157 parts by mass of ethyl acetate, nitrogen gas was introduced while stirring slowly, and the liquid temperature in the flask was maintained at about 65°C, The polymerization reaction was performed for 6 hours 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 above-mentioned (meth)acrylic polymer solution (40 mass %) was diluted to 20 mass % with ethyl acetate, and 500 mass parts of the solution (solid content 100 mass parts) was added as a non-silicone-based polyether. Polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate (Daiichi Kogyo Pharmaceutical Co., Ltd., Aqualon KH-10) 0.3 parts by mass (solid content 0.3 parts by mass), as ether group-free silicon 0.1 part by mass (0.1 part by mass of solid content) of methylphenyl silicone oil of ketone compound (manufactured by Shin-Etsu Chemical Co., Ltd., KF-50-100cs), bis(trifluoromethanesulfonyl)imide as ionic compound of antistatic agent Lithium (manufactured by Tokyo Chemical Industry Co., Ltd., LiTFSI) 0.15 parts by mass (solid content 0.15 parts by mass), and hexamethylene diiso which is an aliphatic isocyanate compound as a crosslinking agent Isocyanurate of cyanate ester (Tosoh Corporation, Coronate HX: C/HX) 3 parts by mass (solid content 3 parts by mass), dibutyltin dilaurate (1 mass % ethyl acetate) as a crosslinking catalyst solution) 2 parts by mass (solid content 0.02 parts by mass), mixed and stirred to prepare an adhesive composition (solution).

<Production of antistatic treatment film>

Prepared by diluting 10 parts by weight of an antistatic agent (Solvex, Microsolver RMd-142, mainly composed of tin oxide and polyester resin) with a mixed solvent consisting of 30 parts by weight of water and 70 parts by weight of methanol Antistatic agent solution.

The obtained antistatic agent solution was applied on a polyethylene terephthalate (PET) film (thickness: 38 μm) as a support film using a Mayer Bar, by drying at 130° C. for 1 minute To remove the solvent, an antistatic layer (thickness: 0.2 μm) was formed, and an antistatic treatment film was produced.

<Production of surface protection film for polarizing plate>

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

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

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

According to the above-mentioned evaluation method, the obtained surface protective film for polarizing plates (surface protective film) and the results of the evaluation of the properties of the polarizing plate to which the surface protective film was pasted were obtained. The results obtained are shown in Table 2.

Hereinafter, the abbreviations in Table 1 will be described.

<Monomer components constituting the (meth)acrylic polymer>

2EHA: 2-ethylhexyl acrylate

AA: Acrylic acid ((meth)acrylic monomer having a carboxyl group)

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

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

<Crosslinking agent>

C/L: Aromatic isocyanate compound, trimethylolpropane/toluene diisocyanate trimer adduct, manufactured by TOSOH, trade name: Coronate L

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

<Polyether>

KH-10: Polyoxyethylene-1-(allyloxymethyl)alkyl ether ammonium sulfate, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., trade name: Aqualon KH-10

HS-10: Polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., trade name: Aqualon HS-10

NF-08: Polyoxyethylene styrenated phenyl ether ammonium sulfate, manufactured by Daiichi Industrial Pharmaceutical Co., Ltd., trade name: Hitenol NF-08

EA-137: Polyoxyethylene styrenated phenyl ether, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., trade name: Noigen EA-137

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

<Silicone compound>

KF-50-100cs: methylphenyl silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-50-100cs

KF-50-1000cs: methylphenyl silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-50-1000cs

KF-50-3000cs: Methyl phenyl silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-50-3000cs

KF-96-100cs: Dimethicone, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-96-100cs

KF-96-1000cs: Dimethicone, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-96-1000cs

KF-96-3000cs: Dimethicone, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-96-3000cs

<Antistatic agent (ionic compound)>

LiTFSI: lithium bis(trifluoromethanesulfonyl)imide, manufactured by Tokyo Chemical Industry Co., Ltd.

From the evaluation results in Table 2 above, it was confirmed that in all the examples, by using the surface protective film for polarizing plates having the adhesive layer in which the silicone compound not containing an ether group in the molecular skeleton was blended, the required surface protection films were obtained. The shear force and the dynamic friction force can achieve both the curl controllability and the smoothness, and the occurrence of contamination and damage to the polarizing plate can be suppressed.

On the other hand, from the result of the said Table 2, in the comparative example 1, since the said silicone compound was not mix|blended, the dynamic friction force could not be suppressed low. In Comparative Example 2, it was confirmed that the shear force was low because the silicone compound was not compounded but the polyether-modified silicone was compounded. In addition, in Comparative Example 3, although the above-mentioned silicone compound was used, it was confirmed that contamination was observed because the compounding amount exceeded the predetermined amount, and there was a problem in practicality.

Claims (5)

A surface protective film for polarizing plates, characterized in that it is a surface protective film for polarizing plates having an adhesive layer formed by an adhesive composition on one or both sides of a support film, and the adhesive composition contains (methyl) An acrylic polymer and a silicone compound represented by the following formula, wherein the (meth)acrylic polymer contains at least 50 to 97 (meth)acrylic monomers having an alkyl group having 1 to 14 carbon atoms. mass %, 2 to 20 mass % of the (meth)acrylic monomer having a hydroxyl group, and 0.001 to less than 2 mass % of the (meth)acrylic monomer having a carboxyl group as monomer components, relative to the aforementioned (meth) ) 100 parts by mass of acrylic polymer, containing 0.01 part by mass to less than 1 part by mass of the above-mentioned silicone compound, the above-mentioned adhesive layer is bonded to the TAC polarizing plate with a bonding area of 1 cm ² , and pasted at 23 ° C for 30 minutes After that, the shear force when stretching at a tensile speed of 0.06 mm/min in the shearing direction is 15 N/cm ² or more, and the surface of the aforementioned adhesive layer is attached to the TAC polarizing plate, and it is attached at 23 ° C for 30 minutes. Then, peel off the surface protection film for the polarizing plate from the TAC polarizing plate, make the brightness enhancement film and the surface of the TAC polarizing plate pasted on the surface of the adhesive layer contact, and apply a load of 200g. The dynamic friction force when stretched at a stretching speed of 100 mm/min in the plane-parallel direction is 1 N or less, [Chemical 1]

In the formula, R and R' are methyl or phenyl, R and R' may be the same or different, and m is 0-3000, and n is 1-3000. The surface protective film for polarizing plates according to claim 1, wherein the adhesive composition contains a surfactant having an alkylene oxide group. The surface protective film for polarizing plates according to claim 1 or 2, wherein the adhesive composition contains an ionic compound. A polarizing plate characterized by being protected by the surface protective film for a polarizing plate according to any one of claims 1 to 3. A method for producing a silicone compound transfer type polarizer, comprising: the step of attaching the surface of the adhesive layer of the surface protection film for polarizer according to any one of claims 1 to 3 to the surface of the polarizer; And the step of peeling the surface protective film for polarizing plates from the surface of the polarizing plate, and transferring the silicone compound contained in the adhesive layer of the surface protective film for polarizing plates to the surface of the polarizing plate.

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