JP7190268B2 - Polarizing film with adhesive layer, method for peeling the same, and image display device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polarizing film and a polarizing film with an adhesive layer having an adhesive layer provided on the polarizing film. Moreover, this invention relates to the method of peeling the said polarizing film with an adhesive layer from a glass substrate. Furthermore, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device, and a PDP using the pressure-sensitive adhesive layer-attached polarizing film.

In a liquid crystal display device, it is essential to dispose polarizing films on both sides of a glass substrate forming a liquid crystal panel surface because of its image forming method. A polarizing film is generally a polarizer made of a polyvinyl alcohol film and a dichroic material such as iodine, and a protective film is attached to one or both sides of the polarizer with a polyvinyl alcohol adhesive or the like. .

When the polarizing film is adhered to a liquid crystal cell or the like, an adhesive is usually used. In addition, the adhesive is provided in advance as an adhesive layer on one side of the polarizing film because it has the advantages of being able to instantly fix the polarizing film and not requiring a drying process to fix the polarizing film. . That is, a polarizing film with an adhesive layer is generally used for attaching the polarizing film.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-attached polarizing film is required to have high durability. For example, problems such as peeling and lifting caused by the pressure-sensitive adhesive layer occur in durability tests by heating, humidification, etc., which are usually performed as environmental accelerated tests. should not occur.

On the other hand, when bonding the polarizing film with an adhesive layer to the glass substrate that forms the surface of the liquid crystal panel, if the bonding position is misaligned or if foreign matter or air bubbles are mixed in and bonding errors occur, the polarizing film It is necessary to separate the film from the glass substrate or the like. However, due to the increasing size of liquid crystal panels and the thinning of liquid crystal cells, it is becoming difficult to peel off the polarizing film with the adhesive layer. is required, the workability is deteriorated, the cell gap of the liquid crystal cell is changed, the display quality is deteriorated, and the liquid crystal cell is damaged. In particular, the piece protective polarizing film with an adhesive layer using a thin polarizer has a thin polarizer and a protective film provided only on one side of the polarizer, so that the overall thickness is very thin. Therefore, there is a problem that the piece protective polarizing film with an adhesive layer using a thin polarizer is easily broken when peeled from a glass substrate or the like. Therefore, the pressure-sensitive adhesive layer is also required to have reworkability that does not cause problems when the polarizing film is peeled off from a glass substrate or the like.

As a method for solving the problem of reworkability, in Patent Document 1, in a method for peeling an adhesive optical film, the adhesive optical film is peeled off from a glass substrate with an optical film in which the adhesive optical film is attached to the glass substrate. and exposing the optical film-attached glass substrate to an environment at a temperature of 40 to 98° C. and a relative humidity of 60 to 99% for 3 minutes or more, and then peeling off the adhesive optical film from the glass substrate in the environment. has been proposed.

Further, in Patent Document 2, in a method for peeling an adhesive optical film from a glass substrate with an optical film in which an adhesive optical film is attached to a glass substrate, the adhesive layer of the adhesive optical film is used. is formed from a water-dispersed adhesive, and after exposing the glass substrate with the optical film to an environment at a temperature of 40 ° C. or higher and a relative humidity of 80% or higher, or at a temperature of 50 ° C. or higher and a relative humidity of 70% or higher, the glass A method for peeling a pressure-sensitive adhesive optical film has been proposed, which is characterized by peeling the pressure-sensitive adhesive optical film from a substrate.

Patent No. 5314439 specification JP 2009-197222 A

However, the peeling method of the pressure-sensitive adhesive optical film of Patent Documents 1 and 2 is an effective peeling method for the pressure-sensitive adhesive layer whose adhesive strength is greatly reduced by heating and humidification, but it is effective for the pressure-sensitive adhesive layer with excellent durability. However, it is not an effective peeling method, and cannot sufficiently solve the problem of reworkability.

An object of the present invention is to provide a method for easily peeling a polarizing film with an adhesive layer from a glass substrate or the like without breaking the adhesive layer, which has excellent durability in high-temperature and/or high-humidity environments. and Another object of the present invention is to provide a pressure-sensitive adhesive layer-attached polarizing film that is excellent in initial reworkability and excellent in durability under high-temperature and/or high-humidity environments. Another object of the present invention is to provide an image display device having the pressure-sensitive adhesive layer-attached polarizing film.

As a result of intensive studies, the present inventors have found that the above-described problems can be solved by the following method for peeling a polarizing film with an adhesive layer and a polarizing film with an adhesive layer, and have completed the present invention.

That is, the present invention provides a method for peeling a polarizing film with an adhesive layer, wherein the polarizing film with an adhesive layer is peeled from a laminate in which the polarizing film with an adhesive layer is attached to a glass substrate by the adhesive layer. and
The pressure-sensitive adhesive layer-attached polarizing film includes a one-sided protective polarizing film having a protective film only on one side of a polarizer and an adhesive layer-attached adhesive layer having an adhesive layer on the polarizer side of the one-sided protective polarizing film directly or via a coating layer. It is a one-sided protective polarizing film,
The pressure-sensitive adhesive layer has an initial adhesive strength to the glass substrate of 2 to 10 N/25 mm, and the adhesive strength to the glass substrate decreases due to contact with water and then increases,
Water is brought into contact with the exposed portion of the adhesive layer of the laminate, and after the adhesive strength of the adhesive layer to the glass substrate decreases to a value of 40% or less of the initial adhesive strength and reaches the minimum value. It relates to a method for peeling a polarizing film with an adhesive layer, characterized in that the polarizing film with an adhesive layer is peeled from the laminate before the adhesive strength increases to a value not exceeding 40% of the initial adhesive strength.

The present inventors have extensively studied the relationship between the physical properties of the pressure-sensitive adhesive layer provided on one side of the polarizing film, the initial reworkability, and the durability under high-temperature and/or high-humidity environments. The present inventors have found that the pressure-sensitive adhesive layer has a peculiar characteristic not found in conventional pressure-sensitive adhesive layers, in which the adhesive strength to a glass substrate decreases upon contact with water and then increases. Then, in a laminate in which a polarizing film with an adhesive layer having an adhesive layer with the properties is attached to a glass substrate by the adhesive layer, water is brought into contact with the exposed portion of the adhesive layer of the laminate. , the pressure-sensitive adhesive layer-attached polarizing film is broken by peeling the pressure-sensitive adhesive layer-attached polarizing film from the laminate after the adhesive strength of the pressure-sensitive adhesive layer to the glass substrate decreases until it increases again. The present inventors have found that the pressure-sensitive adhesive layer-attached polarizing film can be easily peeled off from the glass substrate without damaging the glass substrate.

Further, the pressure-sensitive adhesive layer contains a (meth)acrylic polymer as a base polymer,
The (meth)acrylic polymer, as a monomer unit,
50% by weight or more of alkyl (meth)acrylate (A) whose homopolymer glass transition temperature is lower than 0°C, and alkyl (meth)acrylate (b1) whose homopolymer glass transition temperature is 0°C or higher and homopolymer At least one high Tg monomer (B) selected from the group consisting of (meth)acryloyl group-containing monomers (b2) having a glass transition temperature of 0 ° C. or higher and having a heterocyclic ring 0.1 to 20 weight % is preferable.

Further, the (meth)acrylic polymer, as a monomer unit, is at least one selected from the group consisting of a nitrogen-containing monomer, a carboxyl group-containing monomer, and a hydroxyl group-containing monomer, and the (meth)acryloyl group-containing monomer It is preferable to contain a polar monomer other than (b2).

The nitrogen-containing monomer is preferably a vinyl monomer having a lactam ring. Moreover, the vinyl-based monomer having the lactam ring is preferably a vinylpyrrolidone-based monomer. Further, the vinylpyrrolidone-based monomer is preferably N-vinylpyrrolidone.

In addition, the (meth)acrylic polymer preferably contains 0.1 to 5% by weight of the nitrogen-containing monomer and 0.01 to 3% by weight of the carboxyl group-containing monomer as monomer units. Preferably, the hydroxyl group-containing monomer is contained in an amount of 0.01 to 1% by weight.

The (meth)acrylic polymer preferably has a weight average molecular weight of 900,000 or more.

The pressure-sensitive adhesive layer preferably contains a silane coupling agent having at least one functional group selected from the group consisting of epoxy groups, isocyanate groups, mercapto groups, acid anhydride groups, and amino groups. The content of the silane coupling agent is preferably 0.01 to 3 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer.

The present invention also provides a polarizing film with an adhesive layer having an adhesive layer on one side of the polarizing film,
The pressure-sensitive adhesive layer-attached polarizing film includes a one-sided protective polarizing film having a protective film only on one side of a polarizer and an adhesive layer-attached adhesive layer having an adhesive layer on the polarizer side of the one-sided protective polarizing film directly or via a coating layer. It is a one-sided protective polarizing film,
The pressure-sensitive adhesive layer-attached polarizing film is characterized in that the pressure-sensitive adhesive layer's adhesive strength to a glass substrate decreases upon contact with water and then increases.

The adhesive layer preferably has an initial adhesive strength of 2 to 10 N/25 mm to the glass substrate.

In the adhesive layer, the adhesive strength to the glass substrate after contact with water is reduced by 60% or more relative to the initial adhesive strength, reaches a minimum value, and then increases to 40% or more of the initial adhesive strength. It is preferable that

Further, the pressure-sensitive adhesive layer contains a (meth)acrylic polymer as a base polymer,
The (meth)acrylic polymer, as a monomer unit,
50% by weight or more of alkyl (meth)acrylate (A) whose homopolymer glass transition temperature is lower than 0°C, and alkyl (meth)acrylate (b1) whose homopolymer glass transition temperature is 0°C or higher and homopolymer At least one high Tg monomer (B) selected from the group consisting of (meth)acryloyl group-containing monomers (b2) having a glass transition temperature of 0 ° C. or higher and having a heterocyclic ring 0.1 to 20 weight % is preferable.

Further, the (meth)acrylic polymer, as a monomer unit, is at least one selected from the group consisting of a nitrogen-containing monomer, a carboxyl group-containing monomer, and a hydroxyl group-containing monomer, and the (meth)acryloyl group-containing monomer It is preferable to contain a polar monomer other than (b2).

The nitrogen-containing monomer is preferably a vinyl monomer having a lactam ring. Moreover, the vinyl-based monomer having the lactam ring is preferably a vinylpyrrolidone-based monomer. Further, the vinylpyrrolidone-based monomer is preferably N-vinylpyrrolidone.

In addition, the (meth)acrylic polymer preferably contains 0.1 to 5% by weight of the nitrogen-containing monomer and 0.01 to 3% by weight of the carboxyl group-containing monomer as monomer units. Preferably, the hydroxyl group-containing monomer is contained in an amount of 0.01 to 1% by weight.

The (meth)acrylic polymer preferably has a weight average molecular weight of 900,000 or more.

The pressure-sensitive adhesive layer preferably contains a silane coupling agent having at least one functional group selected from the group consisting of epoxy groups, isocyanate groups, mercapto groups, acid anhydride groups, and amino groups. The content of the silane coupling agent is preferably 0.01 to 3 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer.

The present invention also relates to an image display device having the pressure-sensitive adhesive layer-attached polarizing film.

According to the peeling method of the present invention, the pressure-sensitive adhesive layer-attached polarizing film can be easily peeled from the glass substrate without breaking the pressure-sensitive adhesive layer-attached polarizing film and without damaging the glass substrate. The peeling method of the present invention is particularly suitable for peeling a protective polarizing film with a pressure-sensitive adhesive layer, which is easily broken and which has a protective film only on one side of the polarizer, from a glass substrate. In addition, since the pressure-sensitive adhesive layer-attached polarizing film of the present invention is excellent in initial reworkability, even when a thin polarizer or a one-sided protective polarizing film is used, the polarizing film can be easily peeled off from a glass substrate or the like without breaking. can do. In addition, since the pressure-sensitive adhesive layer-attached polarizing film of the present invention is excellent in durability under high-temperature and/or high-humidity environments, problems such as peeling and lifting caused by the pressure-sensitive adhesive layer are less likely to occur.

BRIEF DESCRIPTION OF THE DRAWINGS It is an example of the schematic sectional drawing of the piece protective polarizing film with an adhesive layer of this invention. 4 is a graph showing changes in adhesive strength of adhesive layer A. FIG. 4 is a graph showing changes in adhesive strength of adhesive layer C. FIG.

The pressure-sensitive adhesive layer-attached polarizing film of the present invention includes a one-sided protective polarizing film having a protective film only on one side of a polarizer and an adhesive having an adhesive layer on the polarizer side of the one-sided protective polarizing film directly or via a coating layer. It is a layered strip protective polarizing film. In addition, from the viewpoint of ensuring reworkability due to a decrease in adhesive strength when in contact with water, it is preferably a piece protective polarizing film with an adhesive layer.

The adhesive layer-attached piece protective polarizing film will be described below with reference to FIG. The adhesive layer-attached piece protective polarizing film 11 has, for example, the piece protective polarizing film 10 and the adhesive layer 4 . The single protective polarizing film 10 has a protective film 2 only on one side of the polarizer 1, as shown in FIG. The polarizer 1 and the protective film 2 are laminated via an adhesive layer 3 (other intervening layers such as an adhesive layer and an undercoat layer (primer layer)). Although not shown, the piece protective polarizing film 10 can be formed by laminating the easy-adhesion layer and the adhesive layer by providing an easy-adhesion layer on the protective film 2 or performing an activation treatment. Although not shown, a plurality of protective films 2 can be provided. A plurality of protective films 2 can be laminated with an adhesive layer 3 (other intervening layers such as an adhesive layer and an undercoat layer (primer layer)).

Further, as shown in FIG. 1 , the adhesive layer 4 in the piece protective polarizing film 11 with an adhesive layer is provided on the polarizer 1 side of the piece protective polarizing film 10 . Moreover, although not shown, a coating layer may be provided between the polarizer 1 and the adhesive layer 4 . The coating layer is not particularly limited, and for example, a known transparent layer or the like described in Japanese Patent No. 6077618 can be applied. A separator 5 can be provided on the adhesive layer 4 of the adhesive layer-attached piece protective polarizing film 11, and a surface protective film 6 can be provided on the opposite side. In the pressure-sensitive adhesive layer-attached piece protective polarizing film 11 of FIG. 1, both the separator 5 and the surface protective film 6 are provided.

<Polarizer>
In the present invention, the thickness of the polarizer is preferably 12 μm or less, more preferably 10 μm or less, even more preferably 8 μm or less, even more preferably 7 μm or less, and particularly preferably from the viewpoint of reducing the thickness and suppressing the occurrence of through cracks. is 6 μm or less. On the other hand, the thickness of the polarizer is preferably 1 μm or more. Such a thin polarizer has little unevenness in thickness, is excellent in visibility, and has little dimensional change, so is excellent in durability against thermal shock.

A polarizer using a polyvinyl alcohol-based resin is used. As a polarizer, for example, hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films are coated with dichroic dyes such as iodine and dichroic dyes. Polyene-based oriented films such as those obtained by adsorbing a substance and uniaxially stretched, polyvinyl alcohol dehydrated products, polyvinyl chloride dehydrochlorinated products, and the like can be mentioned. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is suitable.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or it may be immersed in an aqueous solution of potassium iodide or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol film with water, dirt and anti-blocking agents on the surface of the polyvinyl alcohol film can be washed away, and by swelling the polyvinyl alcohol film, uneven dyeing and other unevenness can be prevented. be. Stretching may be performed after dyeing with iodine, stretching may be performed while dyeing, or dyeing with iodine may be performed after stretching. It can also be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

The polarizer preferably contains boric acid from the viewpoint of stretching stability and optical durability. In addition, the content of boric acid contained in the polarizer is preferably 25% by weight or less, more preferably 20% by weight or less, relative to the total amount of the polarizer, from the viewpoint of suppressing the generation and expansion of penetrating cracks and nanoslits. is preferably 18% by weight or less, further preferably 16% by weight or less. When the content of boric acid contained in the polarizer exceeds 25% by weight, even when the thickness of the polarizer is reduced (for example, the thickness is 12 μm or less), the contraction stress of the polarizer increases and penetrating cracks are likely to occur. It is not preferable because On the other hand, from the viewpoint of stretching stability and optical durability of the polarizer, the boric acid content relative to the total amount of the polarizer is preferably 10% by weight or more, more preferably 12% by weight or more.

As a thin polarizer, typically,
Patent No. 4751486,
Patent No. 4751481 specification,
Patent No. 4815544 specification,
Patent No. 5048120,
Patent No. 5587517 specification,
WO 2014/077599 pamphlet,
International Publication No. 2014/077636,
and the like, or thin polarizers obtained from the production methods described therein.

The polarizer has optical characteristics represented by the single transmittance T and the degree of polarization P of the following formula: P>−(10 ^{0.929T−42.4} −1)×100 (where T<42.3), or
It is preferable to be configured to satisfy the condition of P≧99.9 (where T≧42.3). A polarizer configured to satisfy the above conditions primarily has the performance required for a display for a liquid crystal television using a large display element. Specifically, the contrast ratio is 1000:1 or more and the maximum luminance is 500 cd/m ² or more. As another application, for example, it is attached to the viewing side of an organic EL display device.

On the other hand, a polarizer configured to satisfy the above conditions is thin (for example, a thickness of 12 μm or less) because the constituting polymer (for example, polyvinyl alcohol-based molecule) exhibits high orientation. , the tensile breaking stress in the direction orthogonal to the absorption axis direction of the polarizer is remarkably reduced. As a result, for example, nanoslits are very likely to occur in the absorption axis direction of the polarizer when exposed to mechanical impact exceeding the tensile breaking stress in the manufacturing process of the polarizing film. Therefore, the peeling method of the present invention is particularly suitable for a piece protective polarizing film employing the polarizer (or a piece protective polarizing film with an adhesive layer using the same).

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

<Protective film>
As a material for forming the protective film, a material excellent in transparency, mechanical strength, thermal stability, water barrier property, isotropy, etc. is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, and styrenes such as polystyrene and acrylonitrile-styrene copolymer (AS resin). type polymer, polycarbonate type polymer, and the like. In addition, polyethylene, polypropylene, polyolefins having a cyclo- or norbornene structure, polyolefin-based polymers such as ethylene/propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamides, imide-based polymers, and sulfone-based polymers , polyethersulfone-based polymer, polyetheretherketone-based polymer, polyphenylene sulfide-based polymer, vinyl alcohol-based polymer, vinylidene chloride-based polymer, vinyl butyral-based polymer, arylate-based polymer, polyoxymethylene-based polymer, epoxy-based polymer, or the above Blends of polymers are also examples of polymers that form the protective film.

In addition, one or more types of arbitrary appropriate additives may be contained in the protective film. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, and colorants. The content of the thermoplastic resin in the protective film is preferably 50-100% by weight, more preferably 50-99% by weight, still more preferably 60-98% by weight, and particularly preferably 70-97% by weight. If the content of the thermoplastic resin in the protective film is 50% by weight or less, there is a possibility that the high transparency inherent in the thermoplastic resin may not be fully exhibited.

As the protective film, a retardation film, a brightness enhancement film, a diffusion film, or the like can be used. Examples of the retardation film include those having a front retardation of 40 nm or more and/or a thickness direction retardation of 80 nm or more. The front retardation is usually controlled in the range of 40-200 nm, and the thickness direction retardation is usually controlled in the range of 80-300 nm. When a retardation film is used as the protective film, the retardation film also functions as a polarizer protective film, so that thickness reduction can be achieved.

The retardation film includes a birefringent film obtained by uniaxially or biaxially stretching a thermoplastic resin film. The stretching temperature, stretching ratio, and the like are appropriately set according to the retardation value, film material, and thickness.

Although the thickness of the protective film can be determined as appropriate, it is generally about 1 to 500 μm from the viewpoints of strength, workability such as handleability, and thinness. In particular, the thickness is preferably 1 to 300 μm, more preferably 5 to 200 μm, further preferably 5 to 150 μm, especially 5 to 80 μm.

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

<Intermediate layer>
The protective film and the polarizer are laminated via an intervening layer such as an adhesive layer, pressure-sensitive adhesive layer, or undercoat layer (primer layer). At this time, it is desirable to laminate both without an air gap by an intervening layer. The protective film and the polarizer are preferably laminated via an adhesive layer.

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

Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based adhesives, and water-based polyesters. A water-based adhesive is usually used as an adhesive consisting of an aqueous solution, and usually contains 0.5 to 60% by weight of solids.

Active energy ray-curable adhesives are adhesives that are cured by active energy rays such as electron beams and ultraviolet rays (radical curing type, cationic curing type). can be used. For the active energy ray-curable adhesive, for example, a photoradical-curable adhesive can be used. When a photoradical-curable active energy ray-curable adhesive is used as an ultraviolet-curable adhesive, the adhesive contains a radically polymerizable compound and a photopolymerization initiator.

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

When a water-based adhesive or the like is used, the adhesive is preferably applied so that the thickness of the finally formed adhesive layer is 30 to 300 nm. The thickness of the adhesive layer is more preferably 60-250 nm. On the other hand, when using an active energy ray-curable adhesive, the thickness of the adhesive layer is preferably 0.1 to 200 μm. More preferably, it is 0.5 to 50 μm, still more preferably 0.5 to 10 μm.

In laminating the polarizer and the protective film, an easy-adhesion layer can be provided between the protective film and the adhesive layer. The easy-adhesion layer can be formed of various resins having, for example, a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone system, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, or the like. These polymer resins can be used singly or in combination of two or more. Other additives may be added to form the easy-adhesion layer. More specifically, stabilizers such as tackifiers, ultraviolet absorbers, antioxidants, and heat stabilizers may be used.

The easy-adhesion layer is usually provided in advance on the protective film, and the easy-adhesion layer side of the protective film and the polarizer are laminated by an adhesive layer. Formation of the easy-adhesion layer is carried out by applying a material for forming the easy-adhesion layer onto the protective film by a known technique, followed by drying. The easily adhesive layer-forming material is usually prepared as a solution diluted to an appropriate concentration in consideration of the thickness after drying, the smoothness of coating, and the like. The thickness of the easy-adhesion layer after drying is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm, still more preferably 0.05 to 1 μm. A plurality of easy-adhesion layers can be provided, and in this case also, the total thickness of the easy-adhesion layers is preferably within the above range.

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

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

<Adhesive layer>
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-attached piece protective polarizing film has a pressure-sensitive adhesive strength to a glass substrate that decreases upon contact with water and then increases.

From the viewpoint of reworkability and adhesive properties, the pressure-sensitive adhesive layer preferably has an initial adhesive strength to a glass substrate of 2 to 10 N/25 mm, more preferably 3 to 6 N/25 mm. In the present invention, the initial adhesive force means the adhesive force to the glass substrate before contacting with water.

In addition, from the viewpoint of reworkability and adhesive properties, the adhesive layer has an adhesive strength to the glass substrate after contact with water of 60% or more (preferably 70% or more, more preferably 80% or more), reach the minimum value, and then increase to 40% or more (preferably 45% or more) of the initial adhesive strength.

In addition, from the viewpoint of reworkability and adhesive properties, the pressure-sensitive adhesive layer preferably has a minimum adhesive strength to the glass substrate after contact with water of 30% or less of the initial adhesive strength, more preferably. 20% or less.

The type of adhesive that forms the adhesive layer is not particularly limited. Examples of adhesives include rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, and polyacrylamide-based adhesives. and cellulose-based pressure-sensitive adhesives, but acrylic pressure-sensitive adhesives containing a (meth)acrylic-based polymer as a base polymer are preferred. Acrylic pressure-sensitive adhesives are suitable as materials for forming pressure-sensitive adhesive layers because they have excellent optical transparency, exhibit appropriate wettability, cohesiveness, and adhesive properties such as adhesion, and are excellent in weather resistance, heat resistance, and the like. . A case where an acrylic pressure-sensitive adhesive is used as the material for forming the pressure-sensitive adhesive layer will be described below.

As the (meth)acrylic polymer, a polymer having an alkyl (meth)acrylate monomer unit as a main skeleton can be used. (Meth)acrylate refers to acrylate and/or methacrylate, and has the same meaning as (meth) in the present invention.

The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate, which constitutes the main skeleton of the (meth)acrylic polymer, is about 1 to 18. Specific examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate , octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, etc. can be exemplified. or can be used in combination.

In order to obtain a pressure-sensitive adhesive layer having the above properties, the (meth)acrylic polymer, as a monomer unit, has a homopolymer glass transition temperature of less than 0°C (more preferably −20°C or less, more preferably −40°C or less). ) is 50% by weight or more (more preferably 60% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more), and the glass transition temperature of the homopolymer is 0° C. or higher (more preferably 20° C. or higher, more preferably 40° C. or higher) and the glass transition temperature of the homopolymer is 0° C. or higher (more preferably 20° C. or higher, more preferably is 40° C. or higher), and at least one high Tg monomer (B) selected from the group consisting of heterocyclic (meth)acryloyl group-containing monomers (b2) is added in an amount of 0.1 to 20% by weight (more than preferably 1 to 15% by weight, more preferably 2.5 to 10% by weight, still more preferably 4% to less than 10% by weight). When the alkyl (meth)acrylate (b1) and the (meth)acryloyl group-containing monomer (b2) are used in combination, the weight percentage is the total.

Examples of the alkyl (meth)acrylate (A) include ethyl acrylate (Tg: -24°C), n-butyl acrylate (Tg: -50°C), n-pentyl methacrylate (Tg: -5°C), n- Hexyl acrylate (Tg: -57°C), n-hexyl methacrylate (Tg: -5°C), n-octyl acrylate (Tg: -65°C), n-octyl methacrylate (Tg: -20°C), n-nonyl acrylate (Tg: -58 ° C.), n-lauryl acrylate (Tg: -3 ° C.), n-lauryl methacrylate (Tg: -65 ° C.), n-tetradecyl methacrylate (Tg: -72 ° C.), i-propyl acrylate ( Tg: -3°C), i-butyl acrylate (Tg: -40°C), i-octyl acrylate (Tg: -58°C), i-octyl methacrylate (Tg: -45°C), 2-ethylhexyl acrylate (Tg: −70° C.), 2-ethylhexyl methacrylate (Tg: −10° C.), and the like. These can be used alone or in combination. Among these, at least one selected from ethyl acrylate, n-butyl acrylate, n-pentyl methacrylate, n-hexyl acrylate, and 2-ethylhexyl acrylate is preferably used, and n-butyl acrylate is more preferably used. . The Tg (glass transition temperature) in each parenthesis is the Tg of a homopolymer obtained by polymerizing each monomer. The same applies to the following description.

Examples of the alkyl (meth)acrylate (b1) include methyl acrylate (Tg: 8°C), methyl methacrylate (Tg: 105°C), ethyl methacrylate (Tg: 65°C), n-propyl acrylate (Tg: 3°C ), n-propyl methacrylate (Tg: 35 ° C.), n-pentyl acrylate (Tg: 22 ° C.), n-tetradecyl acrylate (Tg: 24 ° C.), n-hexadecyl acrylate (Tg: 35 ° C.), n- Linear alkyl (meth)acrylates such as hexadecyl methacrylate (Tg: 15°C), n-stearyl acrylate (Tg: 30°C), and n-stearyl methacrylate (Tg: 38°C); t-butyl acrylate (Tg: 43 ° C.), t-butyl methacrylate (Tg: 48 ° C.), i-propyl methacrylate (Tg: 81 ° C.), and i-butyl methacrylate (Tg: 48 ° C.) branched alkyl (meth) acrylates; cyclohexyl acrylate (Tg : 19°C), cyclic alkyl (meth)acrylates such as cyclohexyl methacrylate (Tg: 65°C), isobornyl acrylate (Tg: 94°C), and isobornyl methacrylate (Tg: 180°C). These can be used alone or in combination. Among these, it is preferable to use at least one selected from methyl acrylate, methyl methacrylate, ethyl methacrylate, isobornyl acrylate, and isobornyl methacrylate, and it is selected from methyl acrylate, methyl methacrylate, and isobornyl acrylate. It is more preferable to use at least one of

The (meth)acryloyl group-containing monomer (b2) has a heterocyclic ring. Heterocyclic rings are not particularly limited, and examples thereof include heteroaliphatic rings such as aziridine ring, azetidine ring, pyrrolidine ring, piperidine ring, piperazine ring, and morpholine ring, pyrrole ring, imidazole ring, pyrazole ring, oxazole ring, and isoxazole ring. , thiazole ring, isothiazole ring, pyridine ring, pyrimidine ring, pyridazine ring, and heteroaromatic ring such as pyrazine ring. The heterocyclic ring may be directly bonded to the (meth)acryloyl group, or may be bonded to the (meth)acryloyl group via a connecting group. Among these, a heteroaliphatic ring is preferred, and a morpholine ring is more preferred. Examples of the (meth)acryloyl group-containing monomer (b2) include N-acryloylmorpholine (Tg: 145° C.). These can be used alone or in combination. Among these, it is particularly preferable to use N-acryloylmorpholine.

In the (meth)acrylic polymer, for the purpose of improving adhesiveness, heat resistance, etc., one or more kinds of various monomers can be introduced by copolymerization. Specific examples of such copolymerizable monomers (excluding the (meth)acryloyl group-containing monomer (b2)) include carboxyl group-containing monomers, hydroxyl group-containing monomers, nitrogen-containing monomers, and aromatic group-containing monomers. mentioned.

Examples of carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl(meth)acrylate, carboxypentyl(meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. These can be used alone or in combination.

Hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate. , 10-hydroxydecyl(meth)acrylate, 12-hydroxylauryl(meth)acrylate and (4-hydroxymethylcyclohexyl)-methylacrylate. These can be used alone or in combination.

Nitrogen-containing monomers include, for example, vinyl-based monomers having a lactam ring (e.g., vinylpyrrolidone-based monomers such as N-vinylpyrrolidone and methylvinylpyrrolidone, β-lactam ring, δ-lactam ring, and ε-lactam ring, etc. vinyllactam-based monomers having a lactam ring); maleimide-based monomers such as maleimide, N-cyclohexylmaleimide, and N-phenylmaleimide; (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N- Diethyl (meth)acrylamide, N-hexyl (meth)acrylamide, N-methyl (meth)acrylamide, N-butyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methylolpropane (N-substituted) amide-based monomers such as (meth)acrylamide; aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t (meth)acrylate -Butyl aminoethyl, 3-(3-pyrinidyl) propyl (meth) acrylate and other aminoalkyl (meth) acrylic monomers; N-(meth) acryloyloxymethylene succinimide, N-(meth) acryloyl-6-oxyhexa succinimide-based monomers such as methylenesuccinimide and N-(meth)acryloyl-8-oxyoctamethylenesuccinimide; cyano(meth)acrylate-based monomers such as acrylonitrile and methacrylonitrile; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine , vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides and the like. These can be used alone or in combination.

Examples of aromatic group-containing monomers include benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate and the like. These can be used alone or in combination.

In addition to the above monomers, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; styrenesulfonic acid, allylsulfonic acid, and 2-(meth)acrylamido-2-methylpropanesulfonic acid , (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; and phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate. These can be used alone or in combination.

Furthermore, vinyl monomers such as vinyl acetate, vinyl propionate, styrene, α-methylstyrene, and N-vinylcaprolactam; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; polyethylene glycol (meth)acrylate, ( Glycol-based acrylic ester monomers such as polypropylene glycol meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate ) Acrylic acid ester monomers such as acrylates and 2-methoxyethyl acrylate can also be used. These can be used alone or in combination.

At least one selected from the carboxyl group-containing monomer, the hydroxyl group-containing monomer, and the nitrogen-containing monomer from the viewpoint of improving the cohesive force of the (meth)acrylic polymer and improving the durability of the pressure-sensitive adhesive layer. (excluding the (meth)acryloyl group-containing monomer (b2)) is preferably introduced into the (meth)acrylic polymer by copolymerization, more preferably the carboxyl group-containing monomer, the hydroxyl group-containing A monomer and the nitrogen-containing monomer are introduced into the (meth)acrylic polymer by copolymerization. (Meth)acrylic acid is preferable as the carboxyl group-containing monomer. The hydroxyl group-containing monomer is preferably one or more selected from 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. The nitrogen-containing monomer is preferably a vinyl-based monomer having a lactam ring, more preferably the vinylpyrrolidone-based monomer, and even more preferably N-vinylpyrrolidone. By introducing the nitrogen-containing monomer into the (meth)acrylic polymer by copolymerization, the durability (peeling resistance) of the pressure-sensitive adhesive layer at high temperature and/or high humidity can be improved.

The (meth)acrylic polymer preferably contains 0.01 to 3% by weight, more preferably 0.05 to 1% by weight, and still more preferably 0.05 to 1% by weight of the carboxyl group-containing monomer as a monomer unit. 1 to 0.5% by weight.

The (meth)acrylic polymer preferably contains 0.01 to 1% by weight, more preferably 0.05 to 1% by weight, and still more preferably 0.1% by weight of the hydroxyl group-containing monomer as a monomer unit. ~0.5% by weight.

The (meth)acrylic polymer preferably contains, as a monomer unit, the nitrogen-containing monomer in an amount of 0.1 to 5% by weight, more preferably 0.5 to 3% by weight, and still more preferably 1.5% by weight. ~3% by weight.

Although the weight average molecular weight of the (meth)acrylic polymer is not particularly limited, the weight average molecular weight is usually 800,000 or more, preferably 900,000 or more, from the viewpoint of adhesive properties, weather resistance, heat resistance, and the like. , more preferably 1,000,000 or more.

The (meth)acrylic polymer can be produced by a known method, and for example, a radical polymerization method such as a bulk polymerization method, a solution polymerization method, or a suspension polymerization method can be appropriately selected. As the radical polymerization initiator, various known azo-based and peroxide-based initiators can be used. The reaction temperature is generally about 50-80° C., and the reaction time is 1-8 hours. Further, among the above production methods, the solution polymerization method is preferred, and ethyl acetate, toluene, etc. are generally used as the solvent for the (meth)acrylic polymer.

A cross-linking agent can be added to the adhesive. The cross-linking agent can improve the adhesion and durability, and can improve reliability at high temperatures and maintain the shape of the pressure-sensitive adhesive itself. As the cross-linking agent, an isocyanate-based, epoxy-based, peroxide-based, metal chelate-based, oxazoline-based, or the like can be appropriately used. These cross-linking agents can be used singly or in combination of two or more.

An isocyanate compound is used as the isocyanate-based cross-linking agent. Examples of isocyanate compounds include isocyanate monomers such as tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate, and these isocyanates. Adduct-type isocyanate compounds obtained by adding monomers to trimethylolpropane, etc.; Examples include polymer-type isocyanates.

The isocyanate-based cross-linking agent may be used alone or in combination of two or more. It preferably contains 0.01 to 2 parts by weight of a cross-linking agent, more preferably 0.02 to 2 parts by weight, and further preferably 0.05 to 1.5 parts by weight. preferable. It can be contained as appropriate in consideration of cohesive force, prevention of peeling in a durability test, and the like.

Various peroxides are used as the peroxide-based cross-linking agent. Peroxides include di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butyl peroxyneodecanoate. , t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutyl peroxyisobutyrate, 1 , 1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoylperoxide, t-butylperoxyisobutyrate, and the like. Among these, di(4-t-butylcyclohexyl)peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide, which are particularly excellent in cross-linking reaction efficiency, are preferably used.

One of the peroxides may be used alone, or two or more thereof may be used in combination. It is 0.01 to 2 parts by weight, preferably 0.04 to 1.5 parts by weight, more preferably 0.05 to 1 part by weight. It is appropriately selected within this range in order to adjust workability, reworkability, crosslink stability, peelability, and the like.

The adhesive preferably contains a silane coupling agent. As the silane coupling agent, one having any appropriate functional group can be used. Examples of functional groups include vinyl groups, epoxy groups, amino groups, acid anhydride groups, mercapto groups, (meth)acryloxy groups, acetoacetyl groups, isocyanate groups, styryl groups, and polysulfide groups. Specifically, vinyl group-containing silane coupling agents such as vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane; epoxy group-containing silane coupling agents such as sidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, γ-triethoxysilyl-N-(1,3-dimethylbutylidene) Amino group-containing silane coupling agents such as propylamine and N-phenyl-γ-aminopropyltrimethoxysilane; Acid anhydride group-containing silane coupling agents such as 3-trimethoxysilylpropylsuccinic anhydride; γ-mercaptopropyl mercapto group-containing silane coupling agents such as methyldimethoxysilane; styryl group-containing silane coupling agents such as p-styryltrimethoxysilane; ) acrylic group-containing silane coupling agents; isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane; and polysulfide group-containing silane coupling agents such as bis(triethoxysilylpropyl)tetrasulfide. These can be used alone or in combination. Among these, a silane having at least one functional group selected from the group consisting of an epoxy group, an isocyanate group, a mercapto group, an acid anhydride group, and an amino group in order to form a pressure-sensitive adhesive layer having the properties described above. A coupling agent is preferably used, and more preferably a silane coupling agent having an epoxy group, isocyanate group, mercapto group, or acid anhydride group.

In addition, an oligomer type silane coupling agent may be used to form a pressure-sensitive adhesive layer having the properties described above. Here, the term "oligomer type" refers to a polymer of about dimer or more and less than 100 monomer monomers, and the weight average molecular weight of the oligomer type silane coupling agent is preferably about 300 to 30,000.

Examples of oligomeric silane coupling agents include epoxy group-containing silane coupling agents, mercapto group-containing silane coupling agents, and isocyanate group-containing silane coupling agents, and preferably mercapto group-containing silane coupling agents. , and an isocyanate group-containing silane coupling agent. These can be used alone or in combination.

The epoxy equivalent of the epoxy group-containing silane coupling agent is preferably 250 to 600 g/mol, more preferably 250 to 500 g/mol, from the viewpoint of the durability of the pressure-sensitive adhesive layer in high-temperature and/or high-humidity environments. mol, more preferably 280 to 400 g/mol.

The epoxy group-containing silane coupling agent preferably has two or more alkoxysilyl groups in the molecule. The amount of alkoxy groups in the epoxy group-containing silane coupling agent is preferably 10 to 60% by weight, more preferably 20 to 50% by weight, more preferably 20 to 40% by weight in the silane coupling agent. % is more preferred.

Examples of oligomer type epoxy group-containing silane coupling agents having two or more alkoxysilyl groups in the molecule include X-12-981S, X-12-1231 and X-41 manufactured by Shin-Etsu Chemical Co., Ltd. -1059A, X-41-1056 and the like.

The mercapto equivalent of the mercapto group-containing silane coupling agent is preferably 1000 g/mol or less, more preferably 800 g/mol or less, from the viewpoint of the durability of the pressure-sensitive adhesive layer in a high-temperature and/or high-humidity environment. It is more preferably 700 g/mol or less, and more preferably 500 g/mol or less. Although the lower limit of the mercapto equivalent is not particularly limited, it is preferably 200 g/mol or more.

The mercapto group-containing silane coupling agent preferably has two or more alkoxysilyl groups in the molecule. Further, the amount of the alkoxy group in the mercapto group-containing silane coupling agent is preferably 10 to 60% by weight, more preferably 20 to 50% by weight, more preferably 20 to 40% by weight in the silane coupling agent. % is more preferred.

Examples of oligomeric mercapto group-containing silane coupling agents having two or more alkoxysilyl groups in the molecule include X-41-1805, X-41-1810 and X-41 manufactured by Shin-Etsu Chemical Co., Ltd. -1818, X-12-1156 and the like.

The isocyanate equivalent of the isocyanate group-containing silane coupling agent is preferably 250 to 600 g/mol, more preferably 250 to 500 g/mol, from the viewpoint of the durability of the pressure-sensitive adhesive layer in high-temperature and/or high-humidity environments. mol, more preferably 280 to 400 g/mol.

The isocyanate group-containing silane coupling agent preferably has two or more alkoxysilyl groups in the molecule. Further, the amount of alkoxy groups in the isocyanate group-containing silane coupling agent is preferably 10 to 60% by weight, more preferably 20 to 50% by weight, and 20 to 40% by weight in the silane coupling agent. % is more preferred.

Examples of oligomer type isocyanate group-containing silane coupling agents having two or more alkoxysilyl groups in the molecule include X-40-9318 and X-12-1159L manufactured by Shin-Etsu Chemical Co., Ltd. .

The total content of the silane coupling agent is preferably 0.01 to 3 parts by weight, more preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the base polymer, from the viewpoint of obtaining an adhesive layer with excellent durability. It is 3 parts by weight, more preferably 0.2 to 2 parts by weight.

Also, a silane coupling agent (including an oligomeric silane coupling agent) having at least one functional group selected from the group consisting of an epoxy group, an isocyanate group, a mercapto group, an acid anhydride group, and an amino group. The content is preferably 0.01 to 3 parts by weight, more preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the base polymer, from the viewpoint of obtaining a pressure-sensitive adhesive layer having the above properties, More preferably 0.2 to 2 parts by weight.

Furthermore, the pressure-sensitive adhesive preferably contains a rework improver from the viewpoint of improving reworkability. The rework improver is a chemical substance that has a polar group, easily interacts with the glass interface, and easily segregates at the glass interface. Examples of the rework improver include diols having alkyleneoxy groups such as EO and PO, oligomers having perfluoroalkyl groups, and polyether compounds having reactive silyl groups. As the polyether compound, for example, those disclosed in JP-A-2010-275522 can be used.

Examples of the polyether compound having a reactive silyl group include MS Polymer S203, S303, S810 manufactured by Kaneka; SILYL EST250, EST280; SAT10, SAT200, SAT220, SAT350, SAT400; Or S3430 etc. are mentioned.

The content of the rework improver is preferably 0.001 parts by weight or more, more preferably 0.01 parts by weight or more, and still more preferably 0.1 parts by weight or more with respect to 100 parts by weight of the base polymer, and It is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, even more preferably 2 parts by weight or less, and even more preferably 1 part by weight or less. When the content of the rework improver is less than 0.001 parts by weight, the reworkability of the adhesive layer is difficult to improve, and when it exceeds 10 parts by weight, the adhesive properties of the adhesive layer tend to deteriorate.

Furthermore, the adhesive preferably contains an antistatic agent. When a piece of protective polarizing film with an adhesive layer is attached to a liquid crystal panel during the manufacture of a liquid crystal display device, the release film is peeled off from the adhesive layer of the piece of protective polarizing film with an adhesive layer. Static electricity is generated by peeling of the In addition, when a piece of protective polarizing film with an adhesive layer is attached to a liquid crystal panel, if a bonding error occurs, it is necessary to peel off the polarizing film, but static electricity is generated by peeling the polarizing film. . The generated static electricity affects the orientation of the liquid crystal inside the liquid crystal display device, causing defects. In addition, display unevenness may occur due to static electricity during use of the liquid crystal display device. By adding an antistatic agent to the adhesive, an antistatic function can be imparted to the adhesive layer of the adhesive layer-attached piece protective polarizing film, and these problems can be prevented.

The antistatic agent is not particularly limited, and examples thereof include ionic compounds such as onium-anion salts and alkali metal salts. When an ionic compound is added, it is considered that the ionic compound bleeds out on the surface of the pressure-sensitive adhesive layer, thereby efficiently exhibiting an antistatic function. On the other hand, the contact of the polarizer with the ionic compound may reduce the optical properties such as the degree of polarization. From the viewpoint of suppressing deterioration of the optical properties, it is particularly preferable to use an alkali metal salt.

An alkali metal salt can be an organic salt or an inorganic salt of an alkali metal. Alkali metal salts can be used singly or in combination.

Lithium, sodium, and potassium ions are examples of alkali metal ions that constitute the cation portion of the alkali metal salt. Among these alkali metal ions, lithium ions are preferred.

The anion portion of the alkali metal salt may be composed of an organic substance or may be composed of an inorganic substance. Examples of the anion part constituting the organic salt include CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ )(CF ₃ CO)N ⁻ , ⁻ O ₃ S( CF ₂ ) ₃ SO ₃ ⁻ , PF ₆ ⁻ , CO ₃ ²⁻ , etc. are used. In particular, an anion moiety containing a fluorine atom is preferably used because an ionic compound having good ion dissociation properties can be obtained. Examples of the anion moiety constituting the inorganic salt include Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆₋ , (CN) ₂ N ⁻ , etc. are used. As the anion portion, (perfluoroalkylsulfonyl)imides such as (CF ₃ SO ₂ ) ₂ N ⁻ and (C ₂ F ₅ SO ₂ ) ₂ N ⁻ are preferred, and in particular (CF ₃ SO ₂ ) ₂ N ⁻ . (trifluoromethanesulfonyl) imides are preferred.

Specific examples of alkali metal organic salts include sodium acetate, sodium alginate, sodium ligninsulfonate, sodium toluenesulfonate, LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, Li(CF ₃ SO ₂ )2N, Li _{( C2F5SO2} )2N _, Li _{( C4F9SO2} ) _{2N ,} Li _{( CF3SO2} ) _{3C , KO3S ( CF2} ) _{3SO3K ,} LiO ₃ S(CF ₂ ) ₃ SO ₃ K, among others, LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, Li(C ₂ F ₅ SO ₂ ) ₂ N, Li(C _{4 F9SO2} )2N, Li _{( CF3SO2} ) _3C and the like _are preferred, and Li _{( CF3SO2} ) _2N , _{Li ( C2F5SO2} ) _2N , _{Li ( C4F9SO 2} ) Fluorine-containing lithium imide salts such as ₂ N are more preferred, and (perfluoroalkylsulfonyl) imide lithium salts are particularly preferred.

Examples of alkali metal inorganic salts include lithium perchlorate and lithium iodide.

The content of the alkali metal salt in the adhesive is preferably 0.001 to 5 parts by weight with respect to 100 parts by weight of the base polymer. If the alkali metal salt is less than 0.001 parts by weight, the effect of improving the antistatic performance may not be sufficient. The content of the alkali metal salt is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more. On the other hand, if the content of the alkali metal salt is more than 5 parts by weight, the durability may not be sufficient. The content of the alkali metal salt is preferably 3 parts by weight or less.

As a method for forming an adhesive layer, for example, the adhesive is applied to a release-treated separator or the like, and after drying and removing the polymerization solvent or the like to form an adhesive layer, the polarizer side of the one-sided protective polarizing film ( In the embodiment of FIG. 1, it is produced by a method of transferring to a polarizer), or a method of applying the adhesive and removing the polymerization solvent by drying to form an adhesive layer on the polarizer side. In applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be newly added as appropriate.

Although the thickness of the adhesive layer is not particularly limited, it is preferably 25 μm or less, more preferably 23 μm or less, still more preferably 20 μm or less, and preferably 10 μm or more from the viewpoint of achieving both excellent adhesive properties and reworkability. , more preferably 12 μm or more, and still more preferably 15 μm or more.

A silicone release liner is preferably used as the release-treated separator. In the step of applying the adhesive on such a liner and drying it to form an adhesive layer, as a method for drying the adhesive, an appropriate method can be appropriately adopted depending on the purpose. Preferably, a method of drying the coating film by heating is used. The drying temperature is preferably 40°C to 200°C, more preferably 50°C to 180°C, and particularly preferably 70°C to 170°C. A pressure-sensitive adhesive having excellent adhesive properties can be obtained by setting the heating temperature within the above range.

An appropriate drying time can be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, particularly preferably 10 seconds to 5 minutes.

Various methods are used as a method for forming the pressure-sensitive adhesive layer. Specifically, for example, roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, die coating, etc. A method such as an extrusion coating method can be mentioned.

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a release-treated sheet (separator) until practical use.

Examples of the constituent material of the separator include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. Although thin sheets can be used, plastic films are preferably used because of their excellent surface smoothness.

The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. Examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride Examples include polymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, ethylene-vinyl acetate copolymer films, and the like.

The thickness of the separator is usually about 5-200 μm, preferably about 5-100 μm. If necessary, the separator may be subjected to release and antifouling treatment using a silicone, fluorine, long-chain alkyl or fatty acid amide release agent, silica powder, etc.; It is also possible to perform antistatic treatment such as. In particular, by appropriately subjecting the surface of the separator to release treatment such as silicone treatment, long-chain alkyl treatment, fluorine treatment, etc., the releasability from the pressure-sensitive adhesive layer can be further enhanced.

The pressure-sensitive adhesive layer preferably has a weight change rate calculated by the following formula (1) of 1.1% or more, more preferably 1.2% or more, and still more preferably 1.25% or more. is. If the weight change rate is less than 1.1%, the effect of lowering the adhesive strength when in contact with water is low, resulting in poor reworkability. From the viewpoint of reworkability, the weight change rate is preferably 2.0% or less, more preferably 1.8% or less. In addition, when there are many polar groups, the absolute value of adhesive strength becomes high and rework becomes difficult.
Weight change rate (%) = {(W ₁ -W ₀ )/W ₀ } x 100 (1)
W ₀ = weight of the adhesive layer after drying the adhesive layer at 23° C. for 2 hours W ₁ = the adhesive layer after drying was left at 23° C. 55% RH for 5 hours, and further dried at 60° C. 95% Weight of adhesive layer after standing at RH for 5 hours

<Surface protection film>
A surface protective film can be provided on the adhesive layer-attached piece protective polarizing film. A surface protective film usually has a base film and an adhesive layer, and protects the polarizer via the adhesive layer.

As the base film of the surface protection film, a film material having or near isotropy is selected from the viewpoint of inspection property and management property. Examples of film materials include polyester resins such as polyethylene terephthalate film, cellulose resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, acrylic resins, and the like. Examples include transparent polymers such as resins. Among these, polyester-based resins are preferred. The base film may be used as a laminate of one or more film materials, or may be a stretched product of the film. The thickness of the base film is generally 500 μm or less, preferably 10-200 μm.

Adhesives that form the adhesive layer of the surface protection film include (meth)acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, and adhesives that use fluorine-based or rubber-based polymers as base polymers. can be appropriately selected and used. From the viewpoint of transparency, weather resistance, heat resistance, etc., an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferable. The thickness (dry film thickness) of the adhesive layer is determined according to the required adhesive strength. It is usually about 1 to 100 μm, preferably 5 to 50 μm.

In addition, the surface protective film can be provided with a release treatment layer on the opposite surface of the base film provided with the pressure-sensitive adhesive layer by using a low-adhesion material such as silicone treatment, long-chain alkyl treatment, or fluorine treatment. .

<Other optical layers>
The pressure-sensitive adhesive layer-attached piece protective polarizing film can be used as an optical film laminated with other optical layers in practical use. The optical layer is not particularly limited. One or more optical layers may be used. In particular, a reflective polarizing film or semi-transmissive polarizing film in which a reflector or semi-transmissive reflector is further laminated on a piece of protective polarizing film with an adhesive layer, and a retardation plate is further laminated on a piece of protective polarizing film with an adhesive layer. an elliptically polarizing film or circularly polarizing film, a wide viewing angle polarizing film in which a viewing angle compensation film is further laminated on a piece protective polarizing film with an adhesive layer, or a piece protective polarizing film with an adhesive layer and a brightness enhancement film. A laminated polarizing film is preferred.

The optical film obtained by laminating the above-mentioned optical layer on the protective polarizing film with adhesive layer can be formed by a method of sequentially laminating them separately in the manufacturing process of a liquid crystal display device or the like. This has the advantage of being excellent in stability of quality, assembly work, etc., and improving the manufacturing process of liquid crystal display devices and the like. Appropriate adhesive means such as an adhesive layer can be used for lamination. When the pressure-sensitive adhesive layer-attached piece protective polarizing film and other optical films are adhered, their optical axes can be arranged at an appropriate angle according to the desired retardation properties.

The pressure-sensitive adhesive layer-attached piece protective polarizing film or optical film can be preferably used for forming various image display devices such as liquid crystal display devices and organic EL display devices. Formation of the liquid crystal display device can be carried out according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a protective polarizing film with an adhesive layer or an optical film, and an illumination system as necessary, and incorporating a drive circuit. In the present invention, there is no particular limitation except that the pressure-sensitive adhesive layer-attached piece protective polarizing film or optical film according to the present invention is used, and conventional methods can be applied. As for the liquid crystal cell, any type such as IPS type or VA type can be used, but the IPS type is particularly suitable.

Appropriate liquid crystal displays such as liquid crystal display devices in which a piece of protective polarizing film or optical film with an adhesive layer is arranged on one or both sides of a liquid crystal cell, or devices using a backlight or a reflector in an illumination system can be formed. can. In that case, the pressure-sensitive adhesive layer-attached protective polarizing film or optical film can be placed on one side or both sides of the liquid crystal cell. When the pressure-sensitive adhesive layer-attached piece protective polarizing film or optical film is provided on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, for example, appropriate parts such as a diffuser plate, an anti-glare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffuser plate, and a backlight are arranged in a single layer or at an appropriate position. Two or more layers can be arranged.

<Peeling method of polarizing film with adhesive layer>
The peeling method of the present invention is a method for peeling the adhesive layer-attached piece protective polarizing film from a laminate in which the adhesive layer-attached piece protective polarizing film is attached to a glass substrate by the adhesive layer. ,
Water is brought into contact with the exposed portion of the adhesive layer of the laminate, and the adhesive strength of the adhesive layer to the glass substrate is reduced to 40% (preferably 30%, more preferably 20%) of the initial adhesive strength. from the laminate to the pressure-sensitive adhesive layer from the time of decrease to the time of increase to a value not exceeding 40% (preferably 30%, more preferably 20%) of the initial adhesive strength after reaching the minimum value. It is characterized by peeling off the attached polarizing film.

When the piece protective polarizing film with an adhesive layer is peeled off from the laminate before the adhesive strength decreases to 40% or less of the initial adhesive strength, the adhesive strength of the adhesive layer to the glass substrate is sufficiently reduced. If the protective polarizing film is not attached to the adhesive layer, the protective polarizing film may break or the glass substrate may be damaged. Further, when the adhesive layer-attached protective polarizing film is peeled off from the laminate after the adhesive strength has increased to a value exceeding 40% of the initial adhesive strength, the adhesive strength of the adhesive layer to the glass substrate increases again. Therefore, there is a risk that the protective polarizing film with adhesive layer may break or the glass substrate may be damaged.

The method of bringing water into contact with the exposed portion of the pressure-sensitive adhesive layer of the laminate may be any method as long as liquid water is in contact with the exposed portion of the pressure-sensitive adhesive layer. , a method of applying water to the exposed portion of the pressure-sensitive adhesive layer, and a method of contacting the exposed portion of the pressure-sensitive adhesive layer with a water-containing sponge, waste cloth, or the like.

The temperature of the water to be contacted is not particularly limited, but is usually 15 to 35°C, preferably 20 to 30°C, more preferably 22 to 28°C.

The step of peeling the piece protective polarizing film with the pressure-sensitive adhesive layer from the laminate may be performed while the exposed portion of the pressure-sensitive adhesive layer is in contact with water, or may be performed after the water is removed.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the examples shown below. All parts and percentages in each example are based on weight. All room temperature storage conditions not specified below are 23° C. and 65% RH.

<Preparation of one piece protective polarizing film>
(Production of polarizer)
One surface of an amorphous isophthalic acid-copolymerized polyethylene terephthalate (IPA-copolymerized PET) film (thickness: 100 μm) substrate having a water absorption of 0.75% and a Tg of 75° C. was subjected to corona treatment. Alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (degree of polymerization 1200, degree of acetoacetyl modification 4.6%, degree of saponification 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. , trade name "GOSEFIMER Z200") at a ratio of 9:1 was coated and dried at 25°C to form a PVA-based resin layer having a thickness of 11 µm to prepare a laminate.
The resulting laminate was uniaxially stretched 2.0 times at free ends in the machine direction (longitudinal direction) between rolls with different peripheral speeds in an oven at 120° C. (in-air auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30° C. for 30 seconds (insolubilizing treatment).
Then, it was immersed in a dyeing bath at a liquid temperature of 30° C. while adjusting the iodine concentration and the immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 parts by weight of iodine was blended with 100 parts by weight of water, and 1.0 parts by weight of potassium iodide was blended and immersed for 60 seconds in an iodine aqueous solution (dyeing treatment). .
Next, it was immersed for 30 seconds in a cross-linking bath at a liquid temperature of 30°C (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (crosslinking treatment).
After that, the laminate is immersed in an aqueous solution of boric acid having a liquid temperature of 70° C. (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water). Meanwhile, the film was uniaxially stretched in the machine direction (longitudinal direction) between rolls having different peripheral speeds so that the total draw ratio was 5.5 times (underwater stretching treatment).
After that, the laminate was immersed in a cleaning bath having a liquid temperature of 30° C. (aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
As described above, an optical film laminate containing a polarizer having a thickness of 5 μm and a boric acid content of 16% was obtained. The boric acid content in the polarizer was measured by the following method.

For the obtained polarizer, a Fourier transform infrared spectrophotometer (FTIR) (manufactured by Perkin Elmer, trade name “SPECTRUM2000”) was used to measure boric acid by attenuated total reflection spectroscopy (ATR) using polarized light as the measurement light. The intensity of the peak (665 cm ^-1 ) and the intensity of the reference peak (2941 cm ^-1 ) were measured. From the obtained boric acid peak intensity and reference peak intensity, the boric acid content index was calculated by the following formula, and the boric acid content (% by weight) was determined from the calculated boric acid content index by the following formula.
(Boric acid content index) = (Intensity of boric acid peak 665 cm ^-1 ) / (Intensity of reference peak 2941 cm ^-1 )
(Boric acid content (% by weight)) = (boric acid content index) x 5.54 + 4.1

(Production of transparent protective film)
Transparent protective film: A (meth)acrylic resin film having a thickness of 40 μm and having a lactone ring structure was used after being subjected to a corona treatment on the easy-adhesion-treated surface.

(Preparation of adhesive applied to transparent protective film)
40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloylmorpholine (ACMO) and 3 parts by weight of a photoinitiator "IRGACURE 819" (manufactured by BASF) were mixed to prepare an ultraviolet curing adhesive.

(Preparation of one-sided protective polarizing film)
While applying the UV-curable adhesive to the surface of the polarizer of the optical film laminate so that the thickness of the adhesive layer after curing is 0.5 μm, the transparent protective film is laminated, and then activated. As an energy beam, ultraviolet rays were irradiated to cure the adhesive. Ultraviolet irradiation is performed by a gallium-encapsulated metal halide lamp, irradiation device: Light HAMMER10 manufactured by Fusion UV Systems, Inc., bulb: V bulb, peak illuminance: 1600 mW/cm ² , cumulative irradiation amount 1000/mJ/cm ² (wavelength 380 to 440 nm). ) was used and UV illuminance was measured using a Solatell Sola-Check system. Next, the amorphous PET base material was peeled off, and a single protective polarizing film using a thin polarizer was produced. Using the obtained one piece protective polarizing film, the single transmittance T and the degree of polarization P of the polarizer were measured by the following method. It was 99.99%.

The single transmittance T and the degree of polarization P of the polarizer of the obtained one-piece protective polarizing film were measured using a spectral transmittance meter with an integrating sphere (Murakami Color Research Laboratory Dot-3c).
In addition, the degree of polarization P is the transmittance (parallel transmittance: Tp) when two identical one-sided protective polarizing films are superimposed so that the transmission axes of both are parallel, and is obtained by applying the transmittance (perpendicular transmittance: Tc) when superimposed on , to the following equation. Degree of polarization P (%) = {(Tp-Tc)/(Tp+Tc)} ^1/2 × 100
Each transmittance is indicated by the Y value corrected for luminous efficiency by a 2-degree field of view (C light source) of JIS Z8701, with the fully polarized light obtained through the Glan-Teller prism polarizer being 100%.

<Formation of adhesive layer>
(Preparation of acrylic adhesive A)
89.78 parts of n-butyl acrylate, 8 parts of methyl methacrylate, 1.5 parts of N-vinylpyrrolidone, and 0.2 of acrylic acid were placed in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. and 0.48 parts of 4-hydroxybutyl acrylate were charged. Further, 0.15 part of 2,2'-azobisisobutyronitrile as a polymerization initiator was added to 100 parts of the monomer mixture (solid content) together with ethyl acetate, and nitrogen gas was introduced while gently stirring. After purging with nitrogen, the temperature of the liquid in the flask was maintained at around 60° C., and the polymerization reaction was carried out for 7 hours. Thereafter, ethyl acetate was added to the obtained reaction solution to prepare a solution of an acrylic polymer having a weight-average molecular weight of 1,300,000 adjusted to a solid content concentration of 20%.

The weight average molecular weight (Mw) of the acrylic polymer was measured using a GPC apparatus (HLC-8220GPC) manufactured by Tosoh Corporation. The measurement conditions are as follows.
Sample concentration: 0.2% by mass (THF solution)
Sample injection volume: 10 μl
Eluent: THF
Flow rate: 0.6ml/min
Measurement temperature: 40°C
Column: Sample column; TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column; TSKgel SuperH-RC (1 column)
Detector: differential refractometer (RI)
The weight average molecular weight was obtained in terms of polystyrene.

Per 100 parts of the solid content of the prepared acrylic polymer solution, 1.5 parts of lithium bis (trifluoromethanesulfonyl) imide (manufactured by Mitsubishi Materials Electronic Chemicals), ethylmethylpyrrolidinium-bis (trifluoromethanesulfonyl) imide ( Tokyo Chemical Industry Co., Ltd.) 1 part, isocyanate cross-linking agent (manufactured by Mitsui Chemicals, trade name "Takenate D160N") 0.25 parts, peroxide cross-linking agent (manufactured by NOF Corporation, trade name "Niper BMT40SV") 0 .25 parts, rework improver (manufactured by Kaneka, trade name "SAT10") 0.1 part, antioxidant (manufactured by BASF Japan, trade name "Irganox 1010") 0.3 parts, silane cup containing acetoacetyl group Ring agent (manufactured by Soken Chemical Co., Ltd., trade name "A-100") 0.2 parts, and oligomer type mercapto group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-41-1810") 0 .2 parts were blended to prepare an acrylic pressure-sensitive adhesive A.

(Preparation of acrylic adhesives B and C)
In the preparation of acrylic pressure-sensitive adhesive A, the same method was used, except that the composition of the monomers was changed as shown in Table 1, the polymerization conditions were adjusted, and the types and amounts of additives were changed as shown in Table 1. to prepare an acrylic polymer solution to prepare acrylic pressure-sensitive adhesives B and C.

(Formation of adhesive layers A to C)
Next, the prepared acrylic pressure-sensitive adhesive A, B or C was uniformly applied to the surface of a polyethylene terephthalate film (separator film) treated with a silicone-based release agent using a fountain coater, followed by air circulation at 155°C. It was dried in a constant temperature oven for 1 minute to form an adhesive layer A, B or C on the surface of each separator film.

The compounds in Table 1 are as follows.
BA: n-butyl acrylate 4HBA: 4-hydroxybutyl acrylate AA: acrylic acid NVP: N-vinylpyrrolidone MMA: methyl methacrylate Nyper BMT40SV: dibenzoyl peroxide D160N: isocyanate-based cross-linking agent (manufactured by Mitsui Chemicals)
D110N: isocyanate-based cross-linking agent (manufactured by Mitsui Chemicals, Inc.)
SAT10: rework improver (manufactured by Kaneka Corporation)
LiTFSi: lithium bis (trifluoromethanesulfonyl) imide (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.)
EMPTFSi: Ethylmethylpyrrolidinium-bis(trifluoromethanesulfonyl)imide (manufactured by Tokyo Chemical Industry Co., Ltd.)
Irganox 1010: antioxidant (manufactured by BASF Japan)
A-100: Acetoacetyl group-containing silane coupling agent (manufactured by Soken Chemical Co., Ltd.)
X-41-1810: oligomeric mercapto group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.)

<Measurement of weight change rate>
50 mg of each of the produced pressure-sensitive adhesive layers A to C was placed in a sample basket, set on a device scale, and then subjected to moisture adsorption/desorption measurement using a moisture adsorption/desorption measuring apparatus (manufactured by Hiden, IGA-Sorp). The measurement conditions are as follows. W ₀ and W ₁ obtained by the measurement were substituted into the following formula (1) to calculate the weight change rate.
Drying (pretreatment to remove moisture in the adhesive layer): (100°C, Dry, 1 hour)
Program: (23°C, Dry, 2 hours) (W ₀ ) → (23°C, 55% RH, 5 hours) → (60°C, 95% RH, 5 hours) (W ₁ ) → (23°C, 55% RH, 5 hours)
Measurement mode: Sequence

Weight change rate (%) = {(W ₁ -W ₀ )/W ₀ } x 100 (1)
W ₀ = weight of the adhesive layer after drying the adhesive layer at 23° C. for 2 hours W ₁ = the adhesive layer after drying was left at 23° C. 55% RH for 5 hours, and further dried at 60° C. 95% Weight of adhesive layer after standing at RH for 5 hours

<Measurement of adhesive strength>
Adhesive layer-attached piece protective polarizing films A to C were produced by bonding adhesive layers A to C to the polarizer side of the piece protective polarizing film to obtain samples.
The sample was attached to the surface of an alkali-free glass plate using a laminator, and then autoclaved for 15 minutes at 50° C. and 5 atm for complete adhesion. Thereafter, using a rework device, the initial adhesive force (N/25 mm) was measured when the polarizing film was peeled off from the alkali-free glass plate surface under the conditions of a peeling temperature of 23°C, a peeling speed of 300 mm/min, and a peeling angle of 90 degrees. did.
Also, the sample was adhered to the surface of an alkali-free glass plate using a laminator, followed by autoclaving at 50° C. and 5 atm for 15 minutes for complete adhesion to obtain a laminate. Then, the obtained laminates were immersed in water at 23° C. After 2 hours, one sheet of the laminate was taken out from the water, and the peeling temperature was 23° C., the peeling speed was 300 mm/min, and the peeling angle was 90°. The adhesive force (N/25 mm) was measured when the polarizing film was peeled off from the surface of the alkali-free glass plate. Similar measurements were made after 5 hours and 24 hours of immersion. Table 2 shows the adhesive strength after immersion for 2 hours, after immersion for 5 hours, and after immersion for 24 hours. 2 and 3 are graphs showing changes in the adhesive strength of the adhesive layers A and C. FIG. It can be seen that the adhesive strength of the adhesive layers A and C decreased with the lapse of time due to contact with water, and then increased.

<Evaluation of durability>
The separator film of the adhesive layer-attached piece protective polarizing films A to C (37 inches) thus prepared was peeled off and adhered to non-alkaline glass (manufactured by Corning, EG-XG) having a thickness of 0.7 mm using a laminator. Then, autoclave treatment was performed for 15 minutes under the conditions of 50° C. and 0.5 MPa to completely adhere the polarizing film to the non-acrylic glass. Next, this was placed under the conditions of a heating oven (heating) at 80°C and a constant temperature and humidity machine (humidification) at 60°C/90% RH, and after 500 hours, the polarizing plate was checked for peeling as follows. evaluated according to the standard.
A: Peeling was not observed at all.
◯: Peeling was observed to the extent that it could not be visually confirmed.
Δ: Small peeling that can be visually confirmed was observed.
x: Clear peeling was observed.

Examples 1-2, Comparative Examples 1-10
Each of the adhesive layer-attached protective polarizing films A to C thus prepared was attached to the surface of a non-alkali glass plate using a laminator, and then autoclaved at 50°C and 5 atm for 15 minutes to completely adhere to each other to form a laminate. The obtained laminate was immersed in water at 23°C. The peeling timing was adjusted based on the results of adhesive strength in Table 2, which had been measured in advance. After the immersion time shown in Table 3, the laminate was removed from the water, and the polarizing film was removed from the surface of the alkali-free glass plate using a rework device under the conditions of a peeling temperature of 23°C, a peeling speed of 300 mm/min, and a peeling angle of 90 degrees. The adhesive strength (N/25 mm) when peeled was measured. In addition, reworkability was evaluated according to the following criteria. Table 3 shows the results.
A: The polarizing film can be easily peeled off without breakage of the polarizing film or breakage of the glass.
◯: The polarizing film can be peeled off without breakage of the polarizing film or breakage of the glass.
Δ: The polarizing film can be peeled off, although breakage of the polarizing film and breakage of the glass may occur.
x: Breakage of the polarizing film and breakage of the glass occurred, and the polarizing film could not be peeled off.

The pressure-sensitive adhesive layer-carrying polarizing film of the present invention can be used alone or as an optical film laminated thereon for image display devices such as liquid crystal display devices (LCD) and organic EL display devices.

Reference Signs List 1 Polarizer 2 Protective film 3 Adhesive layer 4 Adhesive layer 5 Separator 6 Surface protective film 10 Piece protective polarizing film 11 Piece protective polarizing film with adhesive layer

Claims (24)

A method for peeling a polarizing film with an adhesive layer, wherein the polarizing film with an adhesive layer is peeled off from a laminate in which the polarizing film with an adhesive layer is attached to a glass substrate by the adhesive layer,
The pressure-sensitive adhesive layer-attached polarizing film includes a one-sided protective polarizing film having a protective film only on one side of a polarizer and an adhesive layer-attached adhesive layer having an adhesive layer on the polarizer side of the one-sided protective polarizing film directly or via a coating layer. It is a one-sided protective polarizing film,
The pressure-sensitive adhesive layer contains a base polymer and a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an isocyanate group, a mercapto group, an acid anhydride group, and an amino group. ,
The pressure-sensitive adhesive layer has a weight change rate calculated by the following formula (1) of 1.1% or more and 2.0% or less,
Weight change rate (%) = {(W1- _{W0 )} / W0 _} x 100 (1)
W ₀ = Weight of the adhesive layer after drying the adhesive layer at 23° C. for 2 hours
W ₁ = The weight of the adhesive layer after the dried adhesive layer was left at 23°C and 55% RH for 5 hours, and then at 60°C and 95% RH for 5 hours.
The pressure-sensitive adhesive layer has an initial adhesive force to a glass substrate of 2 to 10 N/25 mm, and the adhesive force to the glass substrate decreases when it comes into contact with water, and then increases when it comes into contact with water. ,
When the laminate is immersed in water at 23° C. and water is brought into contact with the exposed portion of the adhesive layer, and the adhesive strength of the adhesive layer to the glass substrate is reduced to 40% or less of the initial adhesive strength. From, until it increases to a value that does not exceed 40% of the initial adhesive strength after reaching the minimum value, the adhesive layer-attached polarizing film is peeled from the laminate. A method for peeling a polarizing film. The pressure-sensitive adhesive layer contains a (meth)acrylic polymer as a base polymer,
The (meth)acrylic polymer, as a monomer unit,
50% by weight or more of alkyl (meth)acrylate (A) whose homopolymer glass transition temperature is lower than 0°C, and alkyl (meth)acrylate (b1) whose homopolymer glass transition temperature is 0°C or higher and homopolymer At least one high Tg monomer (B) selected from the group consisting of (meth)acryloyl group-containing monomers (b2) having a glass transition temperature of 0 ° C. or higher and having a heterocyclic ring 0.1 to 20 weight % of the pressure-sensitive adhesive layer-attached polarizing film according to claim 1. The (meth)acrylic polymer, as a monomer unit, is at least one selected from the group consisting of a nitrogen-containing monomer, a carboxyl group-containing monomer, and a hydroxyl group-containing monomer, and the (meth)acryloyl group-containing monomer (b2 ). The method for peeling the pressure-sensitive adhesive layer-attached polarizing film according to claim 2, which contains a polar monomer other than ). The method for peeling a polarizing film with an adhesive layer according to claim 3, wherein the nitrogen-containing monomer is a vinyl-based monomer having a lactam ring. The method for peeling a polarizing film with an adhesive layer according to claim 4, wherein the vinyl-based monomer having a lactam ring is a vinylpyrrolidone-based monomer. 6. The method for peeling a polarizing film with an adhesive layer according to claim 5, wherein the vinylpyrrolidone-based monomer is N-vinylpyrrolidone. The method for peeling a polarizing film with an adhesive layer according to any one of claims 3 to 6, wherein the (meth)acrylic polymer contains 0.1 to 5% by weight of the nitrogen-containing monomer as a monomer unit. The method for peeling a polarizing film with an adhesive layer according to any one of claims 3 to 7, wherein the (meth)acrylic polymer contains 0.01 to 3% by weight of the carboxyl group-containing monomer as a monomer unit. The method for peeling a polarizing film with an adhesive layer according to any one of claims 3 to 8, wherein the (meth)acrylic polymer contains 0.01 to 1% by weight of the hydroxyl group-containing monomer as a monomer unit. The method for peeling a polarizing film with an adhesive layer according to any one of claims 2 to 9, wherein the (meth)acrylic polymer has a weight average molecular weight of 900,000 or more. The method for peeling a polarizing film with an adhesive layer according to any one of claims 1 to 10 , wherein the content of the silane coupling agent is 0.01 to 3 parts by weight with respect to 100 parts by weight of the base polymer . A polarizing film with an adhesive layer having an adhesive layer on one side of the polarizing film,
The pressure-sensitive adhesive layer-attached polarizing film includes a one-sided protective polarizing film having a protective film only on one side of a polarizer and an adhesive layer-attached adhesive layer having an adhesive layer on the polarizer side of the one-sided protective polarizing film directly or via a coating layer. It is a one-sided protective polarizing film,
The pressure-sensitive adhesive layer contains a base polymer and a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an isocyanate group, a mercapto group, an acid anhydride group, and an amino group. ,
The pressure-sensitive adhesive layer has a weight change rate calculated by the following formula (1) of 1.1% or more and 2.0% or less,
Weight change rate (%) = {(W1- _{W0 )} / W0 _} x 100 (1)
W ₀ = Weight of the adhesive layer after drying the adhesive layer at 23° C. for 2 hours
W ₁ = The weight of the adhesive layer after the dried adhesive layer was left at 23°C and 55% RH for 5 hours, and then at 60°C and 95% RH for 5 hours.
In the pressure-sensitive adhesive layer, the adhesive force to the glass substrate decreases when it comes into contact with water, and then increases when it comes into contact with water ,
When the laminate in which the adhesive layer-attached polarizing film is attached to the glass substrate by the adhesive layer is immersed in water at 23 ° C. and the exposed part of the adhesive layer is brought into contact with water, the adhesive The adhesion of the layer to the glass substrate after contact with water decreases by 60% or more relative to the initial adhesion, reaches a minimum value, and then increases to 40% or more of the initial adhesion. A polarizing film with an adhesive layer characterized by: 13. The polarizing film with an adhesive layer according to claim 12 , wherein the adhesive layer has an initial adhesive strength to a glass substrate of 2 to 10 N/25 mm. The pressure-sensitive adhesive layer contains a (meth)acrylic polymer as a base polymer,
The (meth)acrylic polymer, as a monomer unit,
50% by weight or more of alkyl (meth)acrylate (A) whose homopolymer glass transition temperature is lower than 0°C, and alkyl (meth)acrylate (b1) whose homopolymer glass transition temperature is 0°C or higher and homopolymer At least one high Tg monomer (B) selected from the group consisting of (meth)acryloyl group-containing monomers (b2) having a glass transition temperature of 0 ° C. or higher and having a heterocyclic ring 0.1 to 20 weight % of the pressure-sensitive adhesive layer-attached polarizing film according to claim 12 or 13 . The (meth)acrylic polymer, as a monomer unit, is at least one selected from the group consisting of a nitrogen-containing monomer, a carboxyl group-containing monomer, and a hydroxyl group-containing monomer, and the (meth)acryloyl group-containing monomer (b2 15. The polarizing film with an adhesive layer according to claim 14 , which contains a polar monomer other than ). The pressure-sensitive adhesive layer-attached polarizing film according to claim 15 , wherein the nitrogen-containing monomer is a vinyl monomer having a lactam ring. The pressure-sensitive adhesive layer-carrying polarizing film according to claim 16 , wherein the vinyl-based monomer having a lactam ring is a vinylpyrrolidone-based monomer. The pressure-sensitive adhesive layer-attached polarizing film according to claim 17 , wherein the vinylpyrrolidone-based monomer is N-vinylpyrrolidone. The pressure-sensitive adhesive layer-attached polarizing film according to any one of claims 15 to 18 , wherein the (meth)acrylic polymer contains 0.1 to 5% by weight of the nitrogen-containing monomer as a monomer unit. The pressure-sensitive adhesive layer-carrying polarizing film according to any one of claims 15 to 19 , wherein the (meth)acrylic polymer contains, as monomer units, 0.01 to 3% by weight of the carboxyl group-containing monomer. The pressure-sensitive adhesive layer-attached polarizing film according to any one of claims 15 to 20 , wherein the (meth)acrylic polymer contains, as monomer units, 0.01 to 1% by weight of the hydroxyl group-containing monomer. The pressure-sensitive adhesive layer-carrying polarizing film according to any one of claims 14 to 21 , wherein the (meth)acrylic polymer has a weight average molecular weight of 900,000 or more. The pressure-sensitive adhesive layer-attached polarizing film according to any one of claims 12 to 22 , wherein the content of said silane coupling agent is 0.01 to 3 parts by weight with respect to 100 parts by weight of said base polymer . An image display device comprising the pressure-sensitive adhesive layer-attached polarizing film according to any one of claims 12 to 23 .

Images