KR20210025590A - Polarizing film with pressure-sensitive adhesive layer, peeling method thereof, and image display device - Google Patents

Abstract

It is an object of the present invention to provide a method of easily peeling a polarizing film provided with an adhesive layer having an adhesive layer excellent in durability under a high temperature and/or high humidity environment from a glass substrate or the like without breaking. The peeling method of the polarizing film provided with the pressure-sensitive adhesive layer of the present invention is a method of peeling the polarizing film provided with the pressure-sensitive adhesive layer from the laminate in which the polarizing film provided with the pressure-sensitive adhesive layer is affixed to a glass substrate by the pressure-sensitive adhesive layer. In addition, the polarizing film provided with the pressure-sensitive adhesive layer includes a single protective polarizing film having a protective film only on one side of the polarizer, and a pressure-sensitive adhesive layer having an adhesive layer directly on the polarizer side of the single protective polarizing film or through a coating layer. It is a protective polarizing film, and the pressure-sensitive adhesive layer has an initial adhesion to the glass substrate of 2 to 10 N/25 mm, and the adhesion to the glass substrate decreases by contact with water, and then increases. A value that does not exceed 40% of the initial adhesive strength after reaching the minimum value from when water is brought into contact with the exposed portion of the pressure-sensitive adhesive layer and the adhesive force of the pressure-sensitive adhesive layer to the glass substrate is lowered to a value of 40% or less of the initial adhesive force. It is characterized in that the polarizing film provided with the pressure-sensitive adhesive layer is peeled off from the laminate until it is increased to.

Description

Polarizing film with pressure-sensitive adhesive layer, peeling method thereof, and image display device

The present invention relates to a polarizing film including a polarizing film and an adhesive layer having an adhesive layer provided on the polarizing film. Further, the present invention relates to a method of peeling the polarizing film provided with the pressure-sensitive adhesive layer from a glass substrate. Further, 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 polarizing film provided with the pressure-sensitive adhesive layer.

In a liquid crystal display device, it is indispensable to arrange polarizing films on both sides of a glass substrate forming a surface of a liquid crystal panel from the image forming method. In general, a polarizing film is used in which a protective film is bonded to one side or both sides of a polarizer made of a polyvinyl alcohol-based film and a dichroic material such as iodine with a polyvinyl alcohol-based adhesive or the like.

When bonding the polarizing film to a liquid crystal cell or the like, a pressure-sensitive adhesive is usually used. In addition, in terms of having advantages such as that the polarizing film can be instantly fixed and that a drying step is not required to fix the polarizing film, the pressure-sensitive adhesive is previously provided as a pressure-sensitive adhesive layer on one side of the polarizing film. That is, a polarizing film provided with a pressure-sensitive adhesive layer is generally used for adhesion of the polarizing film.

The pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer is required to have high durability, and problems such as peeling or lifting due to the pressure-sensitive adhesive layer are caused in the durability test by heating and humidification, which is usually performed as an environmental promotion test. It is required not to occur.

On the other hand, when bonding a polarizing film with an adhesive layer to a glass substrate forming the surface of a liquid crystal panel, or the like, when the bonding position is shifted or when a bonding error occurs due to foreign matter or air bubbles being mixed, the polarizing film is removed from a glass substrate, etc. It needs to be peeled off. However, due to the increase in the size of the liquid crystal panel or the thinning of the liquid crystal cell, it is becoming difficult to peel the polarizing film provided with the pressure-sensitive adhesive layer, and when the pressure-sensitive adhesive layer has a strong adhesive force, a large force is required for peeling, so workability There are problems such as deterioration or a change in the cell gap of the liquid crystal cell, resulting in a decrease in display quality, or damage to the liquid crystal cell. Particularly, in the single protective polarizing film provided with the pressure-sensitive adhesive layer using a thin polarizer, since the polarizer is thin and the protective film is provided only on one side of the polarizer, the overall thickness is very thin. Therefore, there is a problem that the single protective polarizing film provided with the pressure-sensitive 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 a rework property that does not cause a problem when the polarizing film is peeled from a glass substrate or the like.

As a method of solving the problem of rework property, in Patent Document 1, a method for peeling an adhesive optical film from a glass substrate provided with an optical film on which an adhesive optical film is affixed to a glass substrate is provided. WHEREIN: After exposing the glass substrate provided with the optical film in an environment of a temperature of 40 to 98°C and a relative humidity of 60 to 99% for 3 minutes or more, the adhesive optical film is peeled from the glass substrate under the environment. A method of peeling a molded optical film has been proposed.

In addition, in patent document 2, in the peeling method of the adhesive optical film which peels the adhesive optical film from the glass substrate provided with the optical film on which the adhesive optical film is affixed to a glass substrate, the adhesive layer of the adhesive optical film After exposing the glass substrate with silver, a water-dispersible pressure-sensitive adhesive with an optical film to an environment of 40°C or higher and 80% relative humidity, or 50°C or higher and 70% relative humidity or higher, adhesion from the glass substrate A peeling method of a pressure-sensitive adhesive optical film, characterized by peeling a molded optical film, has been proposed.

Japanese Patent No. 5314439 Specification Japanese Patent Publication No. 2009-197222

However, the peeling method of the pressure-sensitive adhesive optical film of Patent Documents 1 and 2 is an effective peeling method for a pressure-sensitive adhesive layer whose adhesive strength is greatly reduced by heating and humidification, but is not an effective peeling method for a pressure-sensitive adhesive layer having excellent durability. It does not fully solve the problem of rework.

It is an object of the present invention to provide a method of easily peeling a polarizing film provided with an adhesive layer having an adhesive layer excellent in durability under a high temperature and/or high humidity environment from a glass substrate or the like without breaking. In addition, it is an object of the present invention to provide a polarizing film provided with a pressure-sensitive adhesive layer having excellent initial rework properties and excellent durability in a high-temperature and/or high-humidity environment. Another object of the present invention is to provide an image display device having a polarizing film provided with the pressure-sensitive adhesive layer.

As a result of intensive examination, the present inventors found out that the above problem can be solved by the following method of peeling a polarizing film provided with an adhesive layer and a polarizing film provided with an adhesive layer, and reached the present invention.

That is, the present invention is a method for peeling a polarizing film with an adhesive layer, in which the polarizing film with an adhesive layer is peeled from a laminate in which a polarizing film with an adhesive layer is affixed to a glass substrate by the adhesive layer. Is,

The polarizing film provided with the pressure-sensitive adhesive layer includes a single-protection polarizing film having a protective film on only one side of the polarizer, and a single-protection polarizing film having a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer directly on the polarizer side of the single-protective polarizing film or through a coating layer. Is a film,

The pressure-sensitive adhesive layer has an initial adhesion to the glass substrate of 2 to 10 N/25 mm, and the adhesion to the glass substrate decreases by contact with water, and then increases,

When water is brought into contact with the exposed portion of the pressure-sensitive adhesive layer of the laminate and the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer to the glass substrate is lowered to a value of 40% or less of the initial adhesive strength, 40% of the initial adhesive strength is reduced to the minimum value. It relates to a method for peeling a polarizing film with a pressure-sensitive adhesive layer, characterized in that the polarizing film provided with the pressure-sensitive adhesive layer is peeled from the laminate until it is increased to a value not exceeding.

The present inventors have repeatedly studied the relationship between the physical properties of the pressure-sensitive adhesive layer provided on one side of the polarizing film, the initial rework property, and the durability under a high temperature and/or high humidity environment. As a result, the specific pressure-sensitive adhesive layer is a glass substrate. It has been found that the adhesive strength to is lowered by contact with water and then increased, which has a peculiar characteristic not seen in the conventional pressure-sensitive adhesive layer. And, in a laminate in which a polarizing film provided with a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer of the characteristic is affixed to a glass substrate by the pressure-sensitive adhesive layer, water is brought into contact with the exposed portion of the pressure-sensitive adhesive layer of the laminate, and the The polarizing film provided with the pressure-sensitive adhesive layer is not broken by peeling the polarizing film provided with the pressure-sensitive adhesive layer from the laminate until the adhesion of the pressure-sensitive adhesive layer to the glass substrate decreases and then increases again, and It was found that the polarizing film provided with the pressure-sensitive adhesive layer can be easily peeled from the glass substrate without damaging the glass substrate.

In addition, the pressure-sensitive adhesive layer contains a (meth)acrylic polymer as a base polymer,

The (meth)acrylic polymer is a monomer unit,

50% by weight or more of an alkyl (meth)acrylate (A) having a homopolymer having a glass transition temperature of less than 0°C, and

Consisting of an alkyl (meth)acrylate (b1) having a homopolymer having a glass transition temperature of 0°C or higher, and a monomer having a heterocycle having a (meth)acryloyl group-containing monomer (b2) having a glass transition temperature of 0°C or higher It is preferable to contain 0.1 to 20% by weight of at least one high Tg monomer (B) selected from the group.

In addition, the (meth)acrylic polymer is, as a monomer unit, 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 other than the (meth)acryloyl group-containing monomer (b2). It is preferred to contain a polar monomer.

It is preferable that the said nitrogen-containing monomer is a vinyl-type monomer which has a lactam ring. In addition, the vinyl-based monomer having a lactam ring is preferably a vinyl pyrrolidone-based monomer. In addition, 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 as a monomer unit, preferably 0.01 to 3% by weight of the carboxyl group-containing monomer, and the hydroxyl group-containing monomer It is preferred to contain 0.01 to 1% by weight.

In addition, 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 an epoxy group, an isocyanate group, a mercapto group, an acid anhydride group, and an amino group. The content of the silane coupling agent is preferably 0.01 to 3 parts by weight based on 100 parts by weight of the (meth)acrylic polymer.

In addition, the present invention is a polarizing film provided with an adhesive layer having an adhesive layer on one side of the polarizing film,

The polarizing film provided with the pressure-sensitive adhesive layer includes a single-protection polarizing film having a protective film on only one side of the polarizer, and a single-protection polarizing film having a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer directly on the polarizer side of the single protective polarizing film or through a coating layer. Is a film,

The pressure-sensitive adhesive layer relates to a polarizing film with a pressure-sensitive adhesive layer, characterized in that the adhesive force to the glass substrate decreases by contact with water and then increases.

It is preferable that the pressure-sensitive adhesive layer has an initial adhesive strength of 2 to 10 N/25 mm to the glass substrate.

In addition, it is preferable that the adhesive strength of the pressure-sensitive adhesive layer with respect to the glass substrate after contact with water decreases by 60% or more with respect to the initial adhesive force, becomes a minimum value, and then increases by 40% or more of the initial adhesive strength.

In addition, the pressure-sensitive adhesive layer contains a (meth)acrylic polymer as a base polymer,

The (meth)acrylic polymer is a monomer unit,

50% by weight or more of an alkyl (meth)acrylate (A) having a homopolymer having a glass transition temperature of less than 0°C, and

Consisting of an alkyl (meth)acrylate (b1) having a homopolymer having a glass transition temperature of 0°C or higher, and a monomer having a heterocycle having a (meth)acryloyl group-containing monomer (b2) having a glass transition temperature of 0°C or higher It is preferable to contain 0.1 to 20% by weight of at least one high Tg monomer (B) selected from the group.

In addition, the (meth)acrylic polymer is, as a monomer unit, 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 other than the (meth)acryloyl group-containing monomer (b2). It is preferred to contain a polar monomer.

It is preferable that the nitrogen-containing monomer is a vinyl-based monomer having a lactam ring. In addition, the vinyl-based monomer having a lactam ring is preferably a vinyl pyrrolidone-based monomer. In addition, 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 as a monomer unit, preferably 0.01 to 3% by weight of the carboxyl group-containing monomer, and the hydroxyl group-containing monomer It is preferred to contain 0.01 to 1% by weight.

In addition, 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 an epoxy group, an isocyanate group, a mercapto group, an acid anhydride group, and an amino group. The content of the silane coupling agent is preferably 0.01 to 3 parts by weight based on 100 parts by weight of the (meth)acrylic polymer.

Further, the present invention relates to an image display device having a polarizing film provided with the pressure-sensitive adhesive layer.

According to the peeling method of the present invention, the polarizing film provided with the pressure-sensitive adhesive layer is not broken and the polarizing film provided with the pressure-sensitive adhesive layer can be easily peeled from the glass substrate without damaging the glass substrate. The peeling method of this invention has a protective film only on one side of a polarizer, and is especially suitable in the case where a single protective polarizing film provided with an adhesive layer which is easy to break is peeled from a glass substrate. In addition, since the polarizing film provided with the pressure-sensitive adhesive layer of the present invention is excellent in initial rework property, even when a thin polarizer or a single protective polarizing film is used, the polarizing film is easily peeled without breaking from a glass substrate, etc. can do. Further, since the polarizing film provided with the pressure-sensitive adhesive layer of the present invention is excellent in durability under a high temperature and/or high humidity environment, problems such as peeling and lifting due to the pressure-sensitive adhesive layer are unlikely to occur.

1 is an example of a schematic cross-sectional view of a single protective polarizing film provided with the pressure-sensitive adhesive layer of the present invention.
2 is a graph showing the transition of the adhesive force of the pressure-sensitive adhesive layer A.
3 is a graph showing the transition of the adhesive force of the pressure-sensitive adhesive layer C.

The polarizing film provided with the pressure-sensitive adhesive layer of the present invention includes a single protective polarizing film having a protective film only on one side of the polarizer and a pressure-sensitive adhesive layer having an adhesive layer directly on the polarizer side of the single protective polarizing film or through a coating layer. It is a protective polarizing film. In addition, it is preferable that it is a single-protection polarizing film provided with a pressure-sensitive adhesive layer from the viewpoint of securing rework property due to a decrease in adhesion when contacted with water.

Hereinafter, a single protective polarizing film provided with the pressure-sensitive adhesive layer will be described with reference to FIG. 1. The piece protective polarizing film 11 provided with an adhesive layer has the piece protective polarizing film 10 and the adhesive layer 4, for example. As shown in FIG. 1, the single protective polarizing film 10 has the protective film 2 only on one side of the polarizer 1. The polarizer 1 and the protective film 2 are laminated through an adhesive layer 3 (others, an intervening layer such as an adhesive layer and an undercoat layer (primer layer)). In addition, although not shown, in the piece protective polarizing film 10, the easy-adhesion layer and the adhesive layer can be laminated|stacked by providing an easy-adhesive layer on the protective film 2, or by performing an activation process. In addition, although not shown, a plurality of protective films 2 can be provided. The plurality of protective films 2 can be laminated with an adhesive layer 3 (others, an adhesive layer, an intervening layer such as an undercoat layer (primer layer)).

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

<polarizer>

In the present invention, the thickness of the polarizer is preferably 12 μm or less, more preferably 10 μm or less, still more preferably 8 μm or less, and even more preferably 7 from the viewpoint of thinning and suppressing the occurrence of penetration cracks. It is not more than µm, particularly preferably not more than 6 µm. On the other hand, it is preferable that the thickness of the polarizer is 1 μm or more. Such a thin polarizer is excellent in durability against thermal shock because there is little thickness unevenness, excellent visibility, and little dimensional change.

As for the polarizer, what used a polyvinyl alcohol-type resin is used. As a polarizer, for example, a dichroic substance such as iodine or a dichroic dye is adsorbed to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene/vinyl acetate copolymer-based partial saponification film. A polyene-based oriented film, such as a axially stretched thing, a dehydration treatment product of polyvinyl alcohol, a dehydrochloric acid treatment product of polyvinyl chloride, etc. are mentioned. Among these, a polarizer made of a polyvinyl alcohol-based film and a dichroic substance such as iodine is suitable.

A polarizer obtained by uniaxially stretching a polyvinyl alcohol-based film by dyeing it with iodine can be produced by, for example, dyeing by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching to 3 to 7 times the original length. If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, and may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, before dyeing, the polyvinyl alcohol-based film may be immersed in water and washed with water. By washing the polyvinyl alcohol-based film with water, it is possible to wash the surface of the polyvinyl alcohol-based film with an anti-contamination or blocking agent, and by swelling the polyvinyl alcohol-based film, there is also an effect of preventing unevenness such as staining of dyeing. Stretching may be performed after dyeing with iodine, stretching may be performed while dyeing, or may be dyed with iodine after stretching. It can also be stretched in an aqueous solution such as boric acid or potassium iodide or in a water bath.

It is preferable that the polarizer contains boric acid from the viewpoint of stretching stability and optical durability. In addition, the boric acid content contained in the polarizer is preferably 25% by weight or less, further preferably 20% by weight or less, furthermore 18% by weight, with respect to the total amount of the polarizer, from the viewpoint of suppressing the occurrence and expansion of penetration cracks and nano slits. Hereinafter, it is preferably 16% by weight or less. When the boric acid content contained in the polarizer exceeds 25% by weight, even when the thickness of the polarizer is made thin (for example, 12 μm or less in thickness), the shrinkage stress of the polarizer increases and penetration cracks are liable to occur, which is not preferable. . On the other hand, from the viewpoint of stretching stability and optical durability of the polarizer, the boric acid content with respect to the total amount of the polarizer is preferably 10% by weight or more, and further preferably 12% by weight or more.

As a thin polarizer, typically,

Japanese Patent No. 4771486 Specification,

Japanese Patent No.4751481 specification,

Japanese Patent No. 4815544 specification,

Japanese Patent No. 5048120 specification,

Japanese Patent No. 5587517 specification,

International Publication No. 2014/077599 pamphlet,

International Publication No. 2014/077636 pamphlet

The thin polarizers described in the etc. or the thin polarizers obtained from the manufacturing methods described in these are mentioned.

The polarizer has an optical characteristic expressed by a single transmittance T and a polarization degree P by the following formula:

P>-(10 ^0.929T-42.4 -1)×100 (however, T<42.3), or

It is preferable that it is configured to satisfy the condition of P≥99.9 (however, T≥42.3). A polarizer configured to satisfy the above condition has a performance required as a display for a liquid crystal TV using a large display element, uniquely. Specifically, the contrast ratio is 1000:1 or more and the maximum luminance is 500 cd/m 2 or more. As another application, it is bonded to the visual recognition side of an organic EL display device, for example.

On the other hand, the polarizer configured to satisfy the above condition is thin (for example, 12 μm or less in thickness) and the absorption axis of the polarizer, because the polymer (for example, polyvinyl alcohol-based molecule) exhibits high orientation. The tensile breaking stress in the direction orthogonal to the direction becomes remarkably small. As a result, for example, in the manufacturing process of a polarizing film, when exposed to a mechanical shock exceeding the tensile breaking stress, the possibility that nano slits are generated in the direction of the absorption axis of the polarizer is extremely high. Accordingly, the peeling method of the present invention is particularly suitable for a single protective polarizing film employing the polarizer (or a single protective polarizing film provided with an adhesive layer using the same).

As the thin polarizer, among the manufacturing methods including a step of stretching and a step of dyeing in the state of a laminate, since it can be stretched at a high magnification and thus the polarization performance can be improved, Japanese Patent No. 4771486 Specification and Japanese Patent No. 44751481 It is preferable that it is obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution described in the specification of No. 4715544, and in particular, an auxiliary before stretching in an aqueous boric acid solution described in the specification of Japanese Patent No. 44751481 and No. 4815544. It is preferable that it is obtained by a manufacturing method including a step of air-stretching. 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 resin substrate for stretching in the state of a laminate and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it is possible to extend without problems such as fracture due to stretching by being supported by the resin substrate for stretching.

<protective film>

As a material constituting the protective film, those excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropic properties, and the like are 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, polystyrene or acrylonitrile-styrene copolymer Styrene polymers, such as (AS resin), polycarbonate polymers, etc. are mentioned. In addition, polyethylene, polypropylene, polyolefin having a cyclo-based or norbornene structure, polyolefin-based polymer such as ethylene-propylene copolymer, vinyl chloride-based polymer, amide-based polymer such as nylon or aromatic polyamide, imide-based polymer, alcohol Pone polymer, polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, Epoxy polymers, blends of the polymers, and the like are also exemplified as examples of polymers forming the protective film.

Moreover, you may contain 1 or more types of arbitrary suitable additives in a protective film. As an additive, an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, a coloring agent, etc. are mentioned, for example. The content of the thermoplastic resin in the protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the protective film is 50% by weight or less, there is a possibility that the high transparency and the like originally possessed by the thermoplastic resin may not be sufficiently expressed.

As the protective film, a retardation film, a brightness improving film, a diffusion film, or the like can also 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 to 200 nm, and the thickness direction retardation is usually controlled in the range of 80 to 300 nm. When using a retardation film as a protective film, since the said retardation film also functions as a polarizer protective film, thinning can be aimed at.

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

The thickness of the protective film can be appropriately determined, but is generally about 1 to 500 µm in terms of workability such as strength and handling properties, and thin layer properties. Particularly, 1 to 300 µm is preferable, 5 to 200 µm is more preferable, and further, 5 to 150 µm, in particular 5 to 80 µm, is particularly suitable in the case of a thin shape.

Functional layers such as a hard coating layer, an antireflection layer, an anti-sticking layer, a diffusion layer or an anti-glare layer may be provided on the surface of the protective film on which the polarizer is not adhered. In addition, functional layers such as the hard coating layer, antireflection layer, anti-sticking layer, diffusion layer or anti-glare layer may be provided on the protective film itself, or may be provided separately from the protective film.

<Intervening layer>

The protective film and the polarizer are laminated through an intervening layer such as an adhesive layer, an adhesive layer, and a primer layer (primer layer). At this time, it is preferable to stack both with an intervening layer without an air gap. It is preferable that the protective film and the polarizer are laminated through an adhesive layer.

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

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

The active energy ray-curable adhesive is an adhesive that undergoes curing by an active energy ray such as an electron beam or an ultraviolet ray (radical curing type, cation curing type), and can be used, for example, in an electron beam curing type or an ultraviolet curing type. As the active energy ray-curable adhesive, for example, a photo-radical curable adhesive can be used. When a photo-radical curable active energy ray curable adhesive is used as an ultraviolet curable adhesive, the adhesive contains a radical 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 the coating method include a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater, and the like. In addition, a method such as a dipping method can be suitably used for coating.

In addition, in the case of using a water-based adhesive or the like, coating of the adhesive is preferably performed 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 to 250 nm. On the other hand, in the case of 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, and even more preferably 0.5 to 10 µm.

In addition, in lamination of a polarizer and a protective film, an easily bonding 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, and the like. have. These polymer resins may be used alone or in combination of two or more. Further, other additives may be added to the formation of the easily bonding layer. Specifically, stabilizers such as a tackifier, an ultraviolet absorber, an antioxidant, and a heat-resistant stabilizer may be used.

The easy-adhesion layer is usually provided in advance in a protective film, and the easy-adhesion layer side of the said protective film and a polarizer are laminated|stacked by an adhesive layer. The formation of the easy-adhesion layer is performed by coating and drying the forming material of the easy-adhesion layer on a protective film by a known technique. The material for forming the easy-to-adhesion layer is usually adjusted as a solution diluted to an appropriate concentration in consideration of the thickness after drying, smoothness of coating, and the like. The thickness of the easily bonding layer after drying is preferably 0.01 to 5 µm, more preferably 0.02 to 2 µm, and still more preferably 0.05 to 1 µm. In addition, although a plurality of layers of the easily bonding layer can be provided, even in this case, it is preferable that the total thickness of the easily bonding layer is within the above range.

The adhesive layer is formed from an adhesive. As the pressure-sensitive adhesive, various pressure-sensitive adhesives can be used, for example, a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a vinyl alkyl ether-based pressure-sensitive adhesive, a polyvinylpyrrolidone-based pressure-sensitive adhesive, a polyacrylamide-based pressure-sensitive adhesive, and a cellulose-based pressure-sensitive adhesive. have. 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 in that they are excellent in optical transparency, show moderate wettability, cohesiveness and adhesive properties, and are excellent in weather resistance and heat resistance.

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

<Adhesive layer>

In the pressure-sensitive adhesive layer of the piece protective polarizing film provided with the pressure-sensitive adhesive layer, the adhesive force to the glass substrate decreases by contact with water, and then increases.

The pressure-sensitive adhesive layer preferably has an initial adhesive strength of 2 to 10 N/25 mm to a glass substrate, more preferably 3 to 6 N/25 mm, from the viewpoint of rework property and adhesive property. In addition, in this invention, the initial adhesive force means adhesive force with respect to a glass substrate before making it contact with water.

In addition, from the viewpoint of rework property and adhesive properties, the pressure-sensitive adhesive layer has an adhesive force to the glass substrate after contacting with water of 60% or more (preferably 70% or more, more preferably 80%) with respect to the initial adhesive force. It is preferable that it decreases and increases to 40% or more (preferably 45% or more) of the initial adhesive strength after it decreases and becomes the minimum value.

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

The type of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. Examples of the adhesive include rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, vinylalkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. However, an acrylic pressure-sensitive adhesive containing a (meth)acrylic polymer is preferred as the base polymer. The acrylic pressure-sensitive adhesive is suitable as a material for forming a pressure-sensitive adhesive layer because it is excellent in optical transparency, exhibits moderate wettability, cohesiveness and adhesive properties, and is excellent in weather resistance, heat resistance, and the like. Hereinafter, a case where an acrylic pressure-sensitive adhesive is used as a material for forming the pressure-sensitive adhesive layer will be described.

As the (meth)acrylic polymer, one having a monomer unit of an alkyl (meth)acrylate as a main skeleton can be used. In addition, (meth)acrylate means an acrylate and/or methacrylate, and (meth) of this invention has the same meaning.

The number of carbon atoms of the alkyl group of the alkyl (meth)acrylate constituting the main skeleton of the (meth)acrylic polymer is about 1 to 18, and 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 ) Acrylate, stearyl (meth)acrylate and the like can be exemplified, and these can be used alone or 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 glass transition temperature of the homopolymer of less than 0°C (more preferably -20°C or less, more preferably -40°C or less) 50% by weight or more (more preferably 60% by weight or more, still more preferably 70% by weight or more, even more preferably 80% by weight or more) of phosphorus alkyl (meth)acrylate (A), 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. Preferably at least one high Tg monomer (B) selected from the group consisting of a (meth)acryloyl group-containing monomer (b2) having a heterocycle, preferably 20°C or higher, more preferably 40°C or higher) It is preferable to contain 0.1 to 20% by weight (more preferably 1 to 15% by weight, still more preferably 2.5 to 10% by weight, even more preferably 4% by weight or more and less than 10% by weight). Moreover, when the said alkyl (meth)acrylate (b1) and the said (meth)acryloyl group-containing monomer (b2) are used together, it is weight% in total.

Examples of the alkyl (meth)acrylate (A) include ethyl acrylate (Tg: -24°C), n-butyl acrylate (Tg: -50°C), and 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, it is preferable to use at least one selected from ethyl acrylate, n-butyl acrylate, n-pentyl methacrylate, n-hexyl acrylate and 2-ethylhexyl acrylate, and n-butyl acrylate It is more preferable to use. In addition, Tg (glass transition temperature) in each parenthesis is 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), and n-propyl Acrylate (Tg: 3°C), n-propyl methacrylate (Tg: 35°C), n-pentyl acrylate (Tg: 22°C), n-tetradecylacrylate (Tg: 24°C), n-hexa Decyl acrylate (Tg: 35°C), n-hexadecyl methacrylate (Tg: 15°C), n-stearyl acrylate (Tg: 30°C) and n-stearyl methacrylate (Tg: 38°C) Straight-chain alkyl (meth)acrylates such as; 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 chain alkyl (meth)acrylates such as; Cyclohexyl acrylate (Tg: 19°C), cyclohexyl methacrylate (Tg: 65°C), isobornyl acrylate (Tg: 94°C), and isobornyl methacrylate (Tg: 180°C), etc. Alkyl (meth)acrylate, etc. are mentioned. 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 methyl acrylate and methyl methacrylate And it is more preferable to use at least 1 type selected from isobornyl acrylate.

The (meth)acryloyl group-containing monomer (b2) has a heterocycle. The heterocycle is not particularly limited, and examples include heteroaliphatic rings such as aziridine ring, azetidine ring, pyrrolidine ring, piperidine ring, piperazine ring and morpholine ring, pyrrole ring, imidazole ring, pyrazole ring, oxa Heteroaromatic rings, such as a sol ring, an isoxazole ring, a thiazole ring, an isothiazole ring, a pyridine ring, a pyrimidine ring, a pyridazine ring, and a pyrazine ring, etc. are mentioned. The heterocycle may be directly bonded to the (meth)acryloyl group, or may be bonded to the (meth)acryloyl group through a connecting group. Among these, a heteroaliphatic ring is preferable, and a morpholine ring is more preferable. As said (meth)acryloyl group-containing monomer (b2), N-acryloylmorpholine (Tg: 145 degreeC) etc. are mentioned, for example. These can be used alone or in combination. Among these, it is particularly preferable to use N-acryloylmorpholine.

Among the (meth)acrylic polymers, one or more various monomers can be introduced by copolymerization for the purpose of improving adhesiveness, heat resistance, and the like. Specific examples of such a copolymerization monomer (however, excluding the (meth)acryloyl group-containing monomer (b2)) include a carboxyl group-containing monomer, a hydroxyl group-containing monomer, a nitrogen-containing monomer, and an aromatic group-containing monomer.

Examples of the carboxyl group-containing monomer 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.

As a hydroxyl-containing monomer, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8 -Hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)-methylacrylate, and the like. have. These can be used alone or in combination.

Examples of the nitrogen-containing monomer include vinyl-based monomers having a lactam ring (for example, vinylpyrrolidone-based monomers such as N-vinylpyrrolidone and methylvinylpyrrolidone, and β-lactam ring, δ-lactam ring, And vinyl lactam-based monomers having a lactam ring such as an ε-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 (N-substituted) amide monomers such as (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, and N-methylolpropane (meth)acrylamide; Aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, 3-(3-pyridinyl)propyl (meth)acrylate Aminoalkyl (meth)acrylate monomers such as; N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide, etc. Succinimide-based monomer of; 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.

As an aromatic group-containing monomer, benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc. are mentioned, for example. 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 adduct of acrylic acid; Sulfonic acid groups such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid Containing monomers; And phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate. These can be used alone or in combination.

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

From the viewpoint of improving the cohesiveness of the (meth)acrylic polymer and improving the durability of the pressure-sensitive adhesive layer, at least one polar monomer selected from the carboxyl group-containing monomer, the hydroxyl group-containing monomer, and the nitrogen-containing monomer (however, the ( It is preferable to introduce a meth)acryloyl group-containing monomer (excluding b2)) into the (meth)acrylic-based polymer by copolymerization, more preferably the carboxyl group-containing monomer, the hydroxyl group-containing monomer, and the nitrogen-containing monomer. It is introduced into the (meth)acrylic polymer by copolymerization. As the carboxyl group-containing monomer, (meth)acrylic acid is preferable. As the hydroxyl-containing monomer, at least one selected from 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate is preferable. The nitrogen-containing monomer is preferably a vinyl monomer having a lactam ring, more preferably the vinylpyrrolidone monomer, and still more preferably N-vinylpyrrolidone. By introducing the nitrogen-containing monomer into the (meth)acrylic polymer by copolymerization, the durability (peel 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 of the carboxyl group-containing monomer as a monomer unit, more preferably 0.05 to 1% by weight, and still more preferably 0.1 to 0.5% by weight.

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

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

The weight average molecular weight of the (meth)acrylic polymer is not particularly limited, but from the viewpoints of adhesive properties, weather resistance and heat resistance, etc., the weight average molecular weight is usually 800,000 or more, preferably 900,000 or more, and more preferably It is over 1 million.

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

A crosslinking agent may be blended into the pressure-sensitive adhesive. By the crosslinking agent, adhesion and durability can be improved, and reliability at high temperature and retention of the shape of the pressure-sensitive adhesive itself can be achieved. As a crosslinking agent, an isocyanate type, an epoxy type, a peroxide type, a metal chelate type, an oxazoline type, etc. can be used suitably. These crosslinking agents may be used alone or in combination of two or more.

An isocyanate compound is used as an isocyanate crosslinking agent. As an isocyanate compound, tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane di Isocyanate monomers such as isocyanate, and adduct-based isocyanate compounds obtained by adding these isocyanate monomers to trimethylolpropane or the like; Isocyanurates, biuret-type compounds, and urethane prepolymer-type isocyanates obtained by addition reaction of known polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and the like are mentioned.

The isocyanate-based crosslinking agent may be used alone or in combination of two or more, but the total content is 0.01 to 2 parts by weight of the isocyanate-based crosslinking agent based on 100 parts by weight of the base polymer. It is preferably made, more preferably 0.02 to 2 parts by weight, and even more preferably 0.05 to 1.5 parts by weight. In consideration of cohesion force, inhibition of peeling in the durability test, etc., it is possible to appropriately contain.

As the peroxide-based crosslinking agent, various peroxides are used. As peroxide, di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneode Decanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxyisobutyrate , 1,1,3,3-tetramethylbutylperoxy2-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 crosslinking reaction efficiency, are preferably used.

The peroxide may be used alone or in combination of two or more, but the total content is 0.01 to 2 parts by weight of the peroxide based on 100 parts by weight of the base polymer, and 0.04 to 1.5 parts by weight. It is preferable to contain, and it is more preferable to contain 0.05 to 1 part by weight. In order to adjust processability, rework property, crosslinking stability, peelability, etc., it is appropriately selected within this range.

It is preferable that the pressure-sensitive adhesive contains a silane coupling agent. As the silane coupling agent, one having any suitable functional group can be used. As a functional group, a vinyl group, an epoxy group, an amino group, an acid anhydride group, a mercapto group, a (meth)acryloxy group, an acetoacetyl group, an isocyanate group, a styryl group, a polysulfide group, etc. are mentioned, for example. Specifically, vinyl group-containing silane coupling agents such as vinyl triethoxysilane, vinyl tripropoxysilane, vinyl triisopropoxysilane, and vinyl tributoxysilane; γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc. Epoxy group-containing silane coupling agent of; γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, γ-triethoxysilyl Amino group-containing silane coupling agents such as -N-(1,3-dimethylbutylidene)propylamine and N-phenyl-γ-aminopropyltrimethoxysilane; Acid anhydride group-containing silane coupling agents such as 3-trimethoxysilylpropylsuccinic anhydride; mercapto group-containing silane coupling agents such as γ-mercaptopropylmethyldimethoxysilane; styryl group-containing silane coupling agents such as p-styryl trimethoxysilane; (meth)acrylic group-containing silane coupling agents such as γ-acryloxypropyltrimethoxysilane and γ-methacryloxypropyltriethoxysilane; Isocyanate group-containing silane coupling agents such as 3-isocyanate propyl triethoxysilane; Polysulfide group-containing silane coupling agents, such as bis(triethoxysilylpropyl) tetrasulfide, etc. are mentioned. These can be used alone or in combination. Among these, in order to form a pressure-sensitive adhesive layer having the above properties, it is preferable to use 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, More preferably, it is a silane coupling agent which has an epoxy group, an isocyanate group, a mercapto group, or an acid anhydride group.

Further, in order to form the pressure-sensitive adhesive layer having the above properties, an oligomeric silane coupling agent may be used. Here, the oligomer type refers to a polymer having a monomer dimer or more and less than 100 monomers, and the weight average molecular weight of the oligomeric silane coupling agent is preferably about 300 to 30000.

Examples of the oligomeric silane coupling agent include an epoxy group-containing silane coupling agent, a mercapto group-containing silane coupling agent, an isocyanate group-containing silane coupling agent, and the like, and preferably a mercapto group-containing silane coupling agent and an isocyanate group-containing silane It is a 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, further from the viewpoint of durability of the pressure-sensitive adhesive layer in a high temperature and/or high humidity environment. It is preferably 280 to 400 g/mol.

It is preferable that the said epoxy group-containing silane coupling agent has two or more alkoxysilyl groups in a molecule|numerator. Further, the amount of the alkoxy group in the epoxy group-containing silane coupling agent is preferably 10 to 60% by weight, more preferably 20 to 50% by weight, and still more preferably 20 to 40% by weight in the silane coupling agent.

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

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, and 700 g/mol from the viewpoint of durability of the pressure-sensitive adhesive layer in a high temperature and/or high humidity environment. It is even more preferable that it is below, and it is even more preferable that it is 500 g/mol or less. In addition, the lower limit of the mercapto equivalent is not particularly limited, but it is preferably 200 g/mol or more.

It is preferable that the said mercapto group-containing silane coupling agent has two or more alkoxysilyl groups in a molecule|numerator. In addition, 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, and still more preferably 20 to 40% by weight in the silane coupling agent. .

As an oligomeric mercapto group-containing silane coupling agent having two or more alkoxysilyl groups in the molecule, for example, X-41-1805, X-41-1810, 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 durability of the pressure-sensitive adhesive layer in a high temperature and/or high humidity environment, More preferably, it is 280 to 400 g/mol.

It is preferable that the said isocyanate group-containing silane coupling agent has two or more alkoxysilyl groups in a molecule|numerator. In addition, the amount of the alkoxy group in the isocyanate group-containing silane coupling agent is preferably 10 to 60% by weight, more preferably 20 to 50% by weight, and still more preferably 20 to 40% by weight in the silane coupling agent. .

Examples of the oligomeric isocyanate group-containing silane coupling agent 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 content of the entire silane coupling agent is preferably 0.01 to 3 parts by weight, more preferably 0.1 to 3 parts by weight, and still more preferably, based on 100 parts by weight of the base polymer, from the viewpoint of obtaining a pressure-sensitive adhesive layer having excellent durability. It is 0.2 to 2 parts by weight.

In addition, the content of a silane coupling agent (including an oligomer-type 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, has the above characteristics. From the viewpoint of obtaining a pressure-sensitive adhesive layer, it is preferably 0.01 to 3 parts by weight, more preferably 0.1 to 3 parts by weight, and still more preferably 0.2 to 2 parts by weight based on 100 parts by weight of the base polymer.

Moreover, it is preferable that the said adhesive contains a rework improver from a viewpoint of improving rework property. The rework improving agent is a chemical substance that has a polar group, is easy to interact with the glass interface, and is easily segregated at the glass interface. Examples of the rework improving agent include a diol having an alkyleneoxy group such as EO and PO, an oligomer having a perfluoroalkyl group, and a polyether compound having a reactive silyl group. As the polyether compound, those disclosed in Japanese Unexamined Patent Application Publication No. 2010-275522 can be used, for example.

Examples of the polyether compound having a reactive silyl group include MS polymers S203, S303, and S810 manufactured by Kaneka Corporation; SILYL EST250, EST280; SAT10, SAT200, SAT220, SAT350, SAT400, EXCESTAR S2410, S2420 or S3430 manufactured by Asahi Glass Co., Ltd. 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, still more preferably 0.1 parts by weight or more, and preferably 10 parts by weight based on 100 parts by weight of the base polymer. Hereinafter, more preferably 5 parts by weight or less, still more preferably 2 parts by weight or less, and even more preferably 1 part by weight or less. When the content of the rework improving agent is less than 0.001 parts by weight, it becomes difficult to improve the rework property of the pressure-sensitive adhesive layer, and when it exceeds 10 parts by weight, the adhesive property of the pressure-sensitive adhesive layer tends to decrease.

In addition, it is preferable that the pressure-sensitive adhesive contains an antistatic agent. In the production of a liquid crystal display device, when affixing a single protective polarizing film with an adhesive layer to a liquid crystal panel, the release film is peeled from the adhesive layer of the single protective polarizing film provided with an adhesive layer, by peeling the release film. Static electricity is generated. Moreover, when bonding the unprotected polarizing film provided with the pressure-sensitive adhesive layer to the liquid crystal panel, when a bonding error occurs, it is necessary to peel the polarizing film, but static electricity is generated by the peeling of the polarizing film. The generated static electricity affects the alignment of the liquid crystal inside the liquid crystal display device, resulting in defects. In addition, when the liquid crystal display device is used, display unevenness may occur due to static electricity. By adding an antistatic agent to the pressure-sensitive adhesive, it is possible to impart an antistatic function to the pressure-sensitive adhesive layer of the single-protective polarizing film provided with the pressure-sensitive adhesive layer, and to prevent such problems.

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

As the alkali metal salt, an organic or inorganic salt of an alkali metal can be used. Alkali metal salts can be used alone or in combination of two or more.

Examples of the alkali metal ions constituting the cation portion of the alkali metal salt include lithium, sodium, and potassium ions. 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 an inorganic substance. As the anion portion constituting the organic salts, such as ^{_{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 - , etc., CO ₃ ^2- is used. In particular, the anion moiety containing a fluorine atom is preferably used from the viewpoint of obtaining an ionic compound having good ion dissociation properties. As the anion portion constituting the inorganic ^{salts, 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 - or the like is used. As the anion _{portion, (CF 3 SO 2) 2} N -, (C 2 F 5 SO 2) 2 N - a (alkylsulfonyl perfluoroalkyl), etc., and imide preferable, especially _{(CF 3 SO 2) 2 N} - (Trifluoromethanesulfonyl) imide represented by is preferred.

As an organic salt of an alkali metal, specifically, sodium acetate, sodium alginate, sodium lignin sulfonate, sodium toluene sulfonate, LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, Li(CF ₃ SO ₂ ) ₂ N, Li(C ₂ F ₅ SO ₂ ) ₂ N, Li(C ₄ F ₉ SO ₂ ) ₂ N, Li(CF ₃ SO ₂ ) ₃ C, KO ₃ S(CF ₂ ) ₃ SO ₃ K, LiO ₃ S( CF ₂ ) ₃ SO ₃ K and the like, among which LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, Li(C ₂ F ₅ SO ₂ ) ₂ N, Li(C ₄ F ₉ SO ₂ ) ₂ N, Li(CF ₃ SO ₂ ) ₃ C, etc. are preferred, and Li(CF ₃ SO ₂ ) ₂ N, Li(C ₂ F ₅ SO ₂ ) ₂ N, Li(C ₄ F ₉ SO ₂ ) ₂ A fluorine-containing lithium imide salt such as N is more preferable, and a lithium (perfluoroalkylsulfonyl) imide salt is particularly preferable.

Moreover, lithium perchlorate and lithium iodide are mentioned as an inorganic salt of an alkali metal.

The content of the alkali metal salt in the pressure-sensitive adhesive is preferably 0.001 to 5 parts by weight based on 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, and further preferably 0.1 parts by weight or more. On the other hand, when 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 of forming the pressure-sensitive adhesive layer, for example, after applying the pressure-sensitive adhesive to a separator subjected to a peeling treatment, drying and removing a polymerization solvent, etc. to form a pressure-sensitive adhesive layer, the polarizer side of the piece protective polarizing film (in the embodiment of FIG. 1 It is produced by a method of transferring to a polarizer), or a method of forming an adhesive layer on the side of the polarizer by applying the pressure-sensitive adhesive and drying and removing a polymerization solvent or the like. In addition, in the application of the pressure-sensitive adhesive, as appropriate, one or more solvents other than the polymerization solvent may be newly added.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but from the viewpoint of achieving both excellent adhesive properties and rework properties, it is preferably 25 μm or less, more preferably 23 μm or less, still more preferably 20 μm or less, and more preferably Is 10 µm or more, more preferably 12 µm or more, and still more preferably 15 µm or more.

As the separator subjected to the release treatment, a silicone release liner is preferably used. In the step of forming the pressure-sensitive adhesive layer by applying and drying the pressure-sensitive adhesive on such a liner, as a method of drying the pressure-sensitive adhesive, a method appropriately appropriate according to the purpose may be adopted. Preferably, a method of overheating the coating film is used. The heating drying temperature is preferably 40°C to 200°C, more preferably 50°C to 180°C, and particularly preferably 70°C to 170°C. By setting the heating temperature in the above range, an adhesive having excellent adhesive properties can be obtained.

As for the drying time, an appropriate time may be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

As a method of forming the pressure-sensitive adhesive layer, various methods are used. Specifically, for example, by roll coating, kiss roll coating, gravure coating, reverse coating, roll brush, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, die coater, etc. Methods, such as an extrusion coating method, are mentioned.

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a sheet (separator) subjected to a peeling treatment until it is provided for practical use.

As a constituent material of the separator, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film, porous materials such as paper, cloth, and non-woven fabric, nets, foam sheets, metal foils, and laminates thereof, etc. Although a thin leaf body etc. are mentioned, a plastic film is used suitably from the point of excellent surface smoothness.

The plastic film is not particularly limited as long as it is a film capable of protecting the pressure-sensitive adhesive layer, and for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride A copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene-vinyl acetate copolymer film, etc. are mentioned.

The thickness of the separator is usually 5 to 200 µm, preferably about 5 to 100 µm. The separator may be subjected to a release and antifouling treatment with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based releasing agent, silica powder, or the like, or an antistatic treatment such as coating type, mixing type, and vapor deposition type, if necessary. In particular, by appropriately performing a release treatment such as a silicone treatment, a long chain alkyl treatment, or a fluorine treatment on the surface of the separator, the peelability from the pressure-sensitive adhesive layer can be further improved.

The pressure-sensitive adhesive layer preferably has a weight change ratio of 1.1% or more calculated by the following formula (1), more preferably 1.2% or more, and still more preferably 1.25% or more. When the weight change ratio is less than 1.1%, the effect of lowering the adhesive force upon contact with water is low, and reworkability is deteriorated. In addition, from the viewpoint of rework property, the weight change ratio is preferably 2.0% or less, and more preferably 1.8% or less. Moreover, when there are many polar groups, the absolute value of adhesive force becomes high, and rework becomes difficult.

Weight change rate (%)={(W ₁ -W ₀ )/W ₀ }×100 (1)

W ₀ = Weight of the pressure-sensitive adhesive layer after drying the pressure-sensitive adhesive layer at 23° C. for 2 hours

W ₁ = The weight of the pressure-sensitive adhesive layer after the dried pressure-sensitive adhesive layer is left at 23°C 55% RH for 5 hours and then left at 60°C 95% RH for 5 hours

<surface protection film>

A surface protection film can be provided in the piece protective polarizing film provided with the pressure-sensitive adhesive layer. The surface protection film usually has a base film and an adhesive layer, and protects a polarizer through the said adhesive layer.

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

As the pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer of the surface protection film, appropriately select a pressure-sensitive adhesive containing a polymer such as (meth)acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as the base polymer. Can be used. From the viewpoints of transparency, weather resistance, heat resistance, and the like, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferable. The thickness of the pressure-sensitive adhesive layer (dry film thickness) is determined according to the required adhesive force. It is usually about 1 to 100 µm, preferably 5 to 50 µm.

In addition, in the surface protective film, a peeling treatment layer can be provided on the surface opposite to the surface on which the pressure-sensitive adhesive layer is formed in the base film using a low-adhesive material such as a silicone treatment, a long chain alkyl treatment, or a fluorine treatment.

<Other optical layer>

The single protective polarizing film provided with the pressure-sensitive adhesive layer can be used as an optical film laminated with another optical layer at the time of practical use. The optical layer is not particularly limited, but for example, a reflective plate, a transflective plate, a retardation plate (including a wavelength plate such as 1/2 or 1/4), or a liquid crystal display device such as a visual compensation film. One or two or more optical layers may be used. In particular, a reflective polarizing film or a semi-transmissive polarizing film obtained by laminating a reflecting plate or a semi-transmissive reflecting plate in addition to a single protective polarizing film having a pressure-sensitive adhesive layer, and a retardation plate additionally laminated to a single-protective polarizing film having a pressure-sensitive adhesive layer. An elliptically polarizing film or circular polarizing film, a wide viewing angle polarizing film formed by laminating a visual compensation film in addition to a single protective polarizing film equipped with an adhesive layer, or a luminance enhancing film additionally laminated on a single protective polarizing film equipped with an adhesive layer A polarizing film formed is preferable.

An optical film in which the optical layer is laminated on a single protective polarizing film having a pressure-sensitive adhesive layer may be formed by sequentially laminating separately in the manufacturing process of a liquid crystal display device, etc., but the pre-laminated optical film is used as an optical film. , There is an advantage in that the manufacturing process of a liquid crystal display device can be improved due to excellent quality stability and assembly work. For lamination, suitable bonding means such as an adhesive layer can be used. When adhering a single protective polarizing film or other optical film including the pressure-sensitive adhesive layer, their optical axes can be set at an appropriate arrangement angle according to a target retardation characteristic or the like.

The single protective polarizing film or optical film provided with the pressure-sensitive adhesive layer can be preferably used for formation of various image display devices such as a liquid crystal display device and an organic EL display device. The formation of a liquid crystal display device can be performed according to the conventional method. That is, in general, a liquid crystal display device is formed by properly assembling components such as a single-protection polarizing film or an optical film having a liquid crystal cell and an adhesive layer, and a lighting system as necessary to embed a driving circuit. In the present invention, there is no restriction|limiting in particular except for using the piece protective polarizing film or optical film provided with the adhesive layer by this invention, It can follow conventionally. Also for the liquid crystal cell, any type such as IPS type and VA type can be used, but it is particularly suitable for IPS type.

A suitable liquid crystal display device such as a liquid crystal display device in which a single protective polarizing film or optical film provided with an adhesive layer or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector in an illumination system can be formed. In that case, the single protective polarizing film or optical film provided with the pressure-sensitive adhesive layer can be provided on one side or both sides of the liquid crystal cell. When providing a single protective polarizing film or an optical film provided with an adhesive layer on both sides, they may be the same thing or different things may be sufficient. In addition, when forming a liquid crystal display, for example, a diffusion plate, an anti-glare layer, an anti-reflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, etc. It can be placed above.

<The peeling method of the polarizing film provided with an adhesive layer>

The peeling method of the present invention is a method of peeling the piece protective polarizing film provided with the pressure-sensitive adhesive layer from a laminate in which the piece protective polarizing film provided with the pressure-sensitive adhesive layer is affixed to a glass substrate by the pressure-sensitive adhesive layer,

Water is brought into contact with the exposed portion of the pressure-sensitive adhesive layer of the laminate, so that the adhesive strength of the pressure-sensitive adhesive layer to the glass substrate is lowered to a value of 40% (preferably 30%, more preferably 20%) of the initial adhesive strength. From the time of becoming the minimum value until the value is increased to a value not exceeding 40% (preferably 30%, more preferably 20%) of the initial adhesive strength, from the laminate to the pressure-sensitive adhesive layer. It is characterized by peeling off a polarizing film.

If the unprotected polarizing film provided with the pressure-sensitive adhesive layer is peeled from the laminate before the adhesive force is lowered to a value of 40% or less of the initial adhesive force, the adhesive force of the pressure-sensitive adhesive layer to the glass substrate is not sufficiently reduced. There is a fear that the piece protective polarizing film provided with the pressure-sensitive adhesive layer may be broken or the glass substrate may be damaged. In addition, when the adhesive force is increased to a value exceeding 40% of the initial adhesive force and then the unprotected polarizing film provided with the pressure-sensitive adhesive layer is peeled from the laminate, the adhesive force of the pressure-sensitive adhesive layer to the glass substrate is increased again. Therefore, there is a fear that the piece protective polarizing film provided with the pressure-sensitive adhesive layer may be broken 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. For example, a method of immersing the laminate in water, A method of applying water to the exposed portion of the pressure-sensitive adhesive layer, and a method of contacting a sponge or a wafer containing water to the exposed portion of the pressure-sensitive adhesive layer are mentioned.

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

The step of peeling the piece protective polarizing film provided with the pressure-sensitive adhesive layer from the laminate may be performed in a state in which water is brought into contact with the exposed portion of the pressure-sensitive adhesive layer, or after water has been removed.

Example

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the examples shown below. In addition, both parts and% in each example are based on weight. The room temperature standing conditions which are not specifically specified below are all 23 degreeC and 65% RH.

<Preparation of a single protective polarizing film>

(Manufacture of polarizer)

Amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having an absorption rate of 0.75% and a Tg of 75°C was subjected to corona treatment on one side of the substrate, and polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetacetyl-modified PVA (polymerization degree 1200, acetoacetyl modification degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon Kose Chemical Co., Ltd., brand name "Kose Pimer Z200") was 9:1 The aqueous solution contained in the ratio of was applied and dried at 25° C. to form a PVA-based resin layer having a thickness of 11 μm, and a laminate was prepared.

The obtained laminate was uniaxially stretched at a free end by 2.0 times in the longitudinal direction (long side direction) between rolls having different circumferential speeds in an oven at 120°C (air auxiliary stretching treatment).

Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 30°C (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment).

Next, it was immersed in a dyeing bath at a liquid temperature of 30°C while adjusting the iodine concentration and immersion time so that the polarizing plate had a predetermined transmittance. In this Example, 0.2 parts by weight of iodine was blended with respect to 100 parts by weight of water, and 1.0 part by weight of potassium iodide was blended and immersed in an aqueous solution of iodine for 60 seconds (dyeing treatment).

Next, it was immersed for 30 seconds in a crosslinking bath (a solution of boric acid obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid) at a liquid temperature of 30°C (crosslinking treatment).

Thereafter, the laminate was immersed in an aqueous solution of boric acid at 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) at a liquid temperature of 70°C, between rolls having different circumferential speeds. Uniaxial stretching was performed so that the total stretching ratio was 5.5 times in the vertical direction (long side direction) (underwater stretching treatment).

Thereafter, the laminate was immersed in a washing bath at a liquid temperature of 30°C (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) (washing treatment).

By the above, an optical film layered product including 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.

About the obtained polarizer, using a Fourier transform infrared spectrophotometer (FTIR) (manufactured by Perkin Elmer, brand name ``SPECTRUM2000''), by measuring the total reflection attenuation spectroscopy (ATR) using polarized light as the measurement light, the boric acid peak (665 cm ^-1 ) The intensity and intensity of the reference peak (2941cm ^-1 ) were measured. The boric acid amount index was calculated from the obtained boric acid peak intensity and the reference peak intensity by the following formula, and the boric acid content (% by weight) was determined by the following formula from the calculated boric acid amount index.

(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: Corona treatment was applied to the surface of the (meth)acrylic resin film having a lactone ring structure having a thickness of 40 µm to facilitate adhesion and was used.

(Production of adhesive applied to transparent protective film)

An ultraviolet curable adhesive was prepared by mixing 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).

(Preparation of a single protective polarizing film)

On the surface of the polarizer of the optical film laminate, applying the ultraviolet curable adhesive so that the thickness of the cured adhesive layer is 0.5 μm, the transparent protective film is bonded, and then irradiated with ultraviolet rays as an active energy ray, and the adhesive is applied. Cured. Ultraviolet irradiation is a gallium-encapsulated metal halide lamp, irradiation device: Light HAMMER 10 manufactured by Fusion UV Systems, Inc., bulb: V bulb, peak illuminance: 1600 mW/cm 2, integrated irradiation amount 1000/mJ/cm 2 (wavelength 380 to 440 nm) It used, and the illuminance of ultraviolet rays was measured using the Sola-Check system manufactured by Solatell Corporation. Next, the amorphous PET substrate was peeled off, and a single protective polarizing film using a thin polarizer was produced. Using the obtained single-protection polarizing film, when the single transmittance T and the polarization degree P of the polarizer were measured by the following method, the single transmittance T of the polarizer was 42.8%, and the polarization degree P of the polarizer was 99.99%.

The single-piece transmittance T and polarization degree P of the polarizer of the obtained single-protection polarizing film were measured using a spectral transmittance measuring device equipped with an integrating sphere (Dot-3c of Kenkyu-jo Kijutsu, Shikisai Murakami).

In addition, the degree of polarization P is the transmittance (parallel transmittance: Tp) when two identical single protective polarizing films are stacked so that their transmission axes are parallel to each other (parallel transmittance: Tp) and the transmittance (orthogonal transmittance) when they are overlapped so that both transmission axes are orthogonal. : It is obtained by applying Tc) to the following equation. Polarization P(%)={(Tp-Tc)/(Tp+Tc)} ^1/2 × 100

Each transmittance is expressed as a Y value obtained by correcting the visibility according to the second degree field of view (C light source) of JIS Z8701 with 100% of the complete polarization obtained through a Glen Taylor Prism polarizer.

<Formation of adhesive layer>

(Preparation of acrylic adhesive A)

In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet pipe, and cooler, 89.78 parts of n-butyl acrylate, 8 parts of methyl methacrylate, 1.5 parts of N-vinylpyrrolidone, 0.2 parts of acrylic acid and 4-hydride A monomer mixture containing 0.48 parts of oxybutyl acrylate was added. In addition, with respect to 100 parts of the monomer mixture (solid content), 0.15 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator was added together with ethyl acetate, and nitrogen gas was introduced while stirring slowly to replace nitrogen. The polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the vicinity of 60°C. 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 1.3 million, adjusted to a solid content concentration of 20%.

The weight average molecular weight (Mw) of the said acrylic polymer was measured using the Tosoh Corporation GPC apparatus (HLC-8220GPC). Measurement conditions are as follows.

Sample concentration: 0.2% by mass (THF solution)

Sample injection volume: 10 μl

Eluent: THF

Flow rate: 0.6ml/min

Measurement temperature: 40℃

Column: sample column; TSKguardcolumn SuperHZ-H (1EA) + TSKgel SuperHZM-H (2EA)

Reference column; TSKgel SuperH-RC (1 pc.)

Detector: differential refractometer (RI)

The weight average molecular weight was calculated|required in terms of polystyrene.

With respect to 100 parts of the solid content of the prepared acrylic polymer solution, 1.5 parts of lithium bis(trifluoromethanesulfonyl)imide (manufactured by Mitsubishi Material Denshi Kasei), ethylmethylpyrrolidinium-bis(trifluoromethanesulfonyl) already De (manufactured by Tokyo Kasei Kogyo) 1 part, isocyanate-based crosslinking agent (made by Mitsui Chemical, brand name ``Takenate D160N'') 0.25 parts, peroxide-based crosslinking agent (made by Nihon Yushi Corporation, brand name ``Niper BMT40SV'') 0.25 parts, rework improver Kaneka Corporation make, brand name "SAT10") 0.1 part, antioxidant (BASF Japan company make, brand name "Irganox 1010") 0.3 parts, acetoacetyl group-containing silane coupling agent (Sokeng Chemical Corporation, brand name "A-100") 0.2 parts And 0.2 parts of an oligomeric mercapto group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., brand name "X-41-1810") were blended to prepare an acrylic pressure-sensitive adhesive A.

(Preparation of acrylic pressure-sensitive adhesives B and C)

In the preparation of the acrylic pressure-sensitive adhesive A, a solution of the acrylic polymer was prepared in the same manner except that the composition of the monomer was changed as shown in Table 1, the polymerization conditions were adjusted, and the type and amount of additives were changed as shown in Table 1. By preparing, acrylic pressure-sensitive adhesives B and C were prepared.

(Formation of adhesive layers A to C)

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

The compounds in Table 1 are as follows.

BA: n-butyl acrylate

4HBA: 4-hydroxybutylacrylate

AA: acrylic acid

NVP: N-vinylpyrrolidone

MMA: methyl methacrylate

Niper BMT40SV: dibenzoyl peroxide

D160N: Isocyanate crosslinking agent (manufactured by Mitsui Chemical)

D110N: Isocyanate-based crosslinking agent (manufactured by Mitsui Chemical Co., Ltd.)

SAT10: Rework improving agent (manufactured by Kaneka Corporation)

LiTFSi: lithium bis (trifluoromethanesulfonyl) imide (manufactured by Mitsubishi Material Denshi Kasei)

EMPTFSi: ethylmethylpyrrolidinium-bis(trifluoromethanesulfonyl)imide (manufactured by Tokyo Kasei Kogyo)

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>

Each 50 mg of the produced pressure-sensitive adhesive layers A to C was put in a sample basket, set on an apparatus scale, and then water adsorption and desorption measurement was performed using a moisture adsorption and desorption measuring device (manufactured by Hiden, IGA-Sorp). Measurement conditions are as follows. _{The weight change rate was calculated by substituting W 0} and W ₁ obtained in the measurement into the following formula (1).

Drying (pre-treatment to remove moisture in the adhesive layer): (100℃, Dry, 1 hour)

Program:(23℃, Dry, 2 hours)(W ₀ )→(23℃, 55% RH, 5 hours)→(60℃, 95% RH, 5 hours)(W ₁ )→(23℃, 55% RH, 5 hours)

Measurement mode: sequence

Weight change rate (%)={(W ₁ -W ₀ )/W ₀ }×100 (1)

W ₀ = Weight of the pressure-sensitive adhesive layer after drying the pressure-sensitive adhesive layer at 23° C. for 2 hours

W ₁ = The weight of the pressure-sensitive adhesive layer after the dried pressure-sensitive adhesive layer is left at 23°C 55% RH for 5 hours and then left at 60°C 95% RH for 5 hours

<Measurement of adhesive force>

Each of the produced adhesive layers A to C was bonded to the polarizer side of the produced single-protected polarizing film to prepare single-protected polarizing films A to C provided with the pressure-sensitive adhesive layer to obtain a sample.

The sample was affixed to the surface of an alkali-free glass plate using a laminator, and then subjected to an autoclave treatment at 50° C. and 5 atm for 15 minutes to completely adhere. Then, using a rework device, the initial adhesive strength (N/25mm) when the polarizing film was peeled from the surface of the alkali-free glass plate was measured under conditions of a peeling temperature of 23°C, a peeling speed of 300 mm/min, and a peeling angle of 90 degrees. .

Further, the sample was affixed to the surface of an alkali-free glass plate using a laminator, and then subjected to autoclave treatment at 50° C. and 5 atm for 15 minutes to obtain a laminated body. Then, the obtained plurality of laminates were immersed in water at 23°C, and after 2 hours, one sheet of the laminate was taken out in water, and the polarizing film under the conditions of a peeling temperature of 23°C, a peeling rate of 300 mm/min, and a peeling angle of 90 degrees. The adhesive strength (N/25mm) when peeled from the surface of an alkali-free glass plate was measured. The same measurement was performed after 5 hours and 24 hours after immersion. Table 2 shows the adhesive strength after 2 hours of immersion, 5 hours after immersion, and 24 hours after immersion. 2 and 3 are graphs showing the transition of the adhesive strength of the pressure-sensitive adhesive layers A and C. It can be seen that the adhesive strength of the pressure-sensitive adhesive layers A and C decreases with the passage of time due to contact with water, and then increases.

<Evaluation of durability>

The separator film of the single protective polarizing films A to C (37 inches) provided with the produced pressure-sensitive adhesive layer was peeled off and adhered to an alkali-free glass (made by Corning, EG-XG) having a thickness of 0.7 mm using a laminator. Next, an autoclave treatment for 15 minutes was performed under the conditions of 50° C. and 0.5 MPa, so that the polarizing film was completely in close contact with the acrylic-free glass. Next, this was put under the conditions of an 80 degreeC heating oven (heating) and 60 degreeC/90% RH constant temperature and humidity (humidification), respectively, and the presence or absence of peeling of a polarizing plate after 500 hours was evaluated based on the following criteria.

(Double-circle): No peeling was observed at all.

(Circle): Peeling to the extent that it cannot be confirmed visually was seen.

?: Small peeling that can be seen visually was observed.

×: Clear peeling was observed.

Examples 1 to 2, Comparative Examples 1 to 10

Each of the prepared polarizing films A to C having the pressure-sensitive adhesive layer was affixed to the surface of an alkali-free glass plate using a laminator, followed by autoclaving at 50° C. and 5 atm for 15 minutes to completely adhere to the laminate to obtain a laminate. , The obtained laminate was immersed in water at 23°C. The peeling timing was adjusted based on the results of the adhesive force in Table 2 measured in advance. After the immersion time shown in Table 3, the laminate was taken out in water, and the polarizing film was peeled from the surface of the alkali-free glass plate under conditions of a peeling temperature of 23°C, a peeling rate of 300 mm/min, and a peeling angle of 90 degrees using a rework device. The adhesive force (N/25mm) when doing was measured. In addition, the rework property was evaluated based on the following criteria. Table 3 shows the results.

(Double-circle): There is no breakage of a polarizing film or breakage of glass, and a polarizing film can be peeled easily.

○: There is no breakage of the polarizing film or breakage of the glass, and the polarizing film can be peeled off.

(Triangle|delta): Although the breakage of a polarizing film and breakage of a glass may arise, a polarizing film can be peeled.

×: Fracture of the polarizing film and breakage of the glass occur, and the polarizing film cannot be peeled off.

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

1: polarizer
2: protective film
3: adhesive layer, etc.
4: adhesive layer
5: separator
6: surface protection film
10: single protection polarizing film
11: One protective polarizing film provided with an adhesive layer

Claims (27)

It is a peeling method of the polarizing film provided with the adhesive layer, which peels the polarizing film provided with the said adhesive layer from the laminated body in which the polarizing film provided with the adhesive layer was affixed to the glass substrate by the said adhesive layer,
The polarizing film provided with the pressure-sensitive adhesive layer includes a single-protection polarizing film having a protective film on only one side of the polarizer, and a single-protection polarizing film having a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer directly on the polarizer side of the single-protective polarizing film or through a coating layer. Is a film,
The pressure-sensitive adhesive layer has an initial adhesion to the glass substrate of 2 to 10 N/25 mm, and the adhesion to the glass substrate decreases by contact with water, and then increases,
When water is brought into contact with the exposed portion of the pressure-sensitive adhesive layer of the laminate and the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer to the glass substrate is lowered to a value of 40% or less of the initial adhesive strength, 40% of the initial adhesive strength is reduced to the minimum value. A method for peeling a polarizing film with an adhesive layer, characterized in that the polarizing film provided with the pressure-sensitive adhesive layer is peeled from the laminate until it is increased to a value not exceeding. The method according to claim 1, wherein the pressure-sensitive adhesive layer contains a (meth)acrylic polymer as a base polymer,
The (meth)acrylic polymer is a monomer unit,
50% by weight or more of an alkyl (meth)acrylate (A) having a homopolymer having a glass transition temperature of less than 0°C, and
Consisting of an alkyl (meth)acrylate (b1) having a homopolymer having a glass transition temperature of 0°C or higher, and a monomer having a heterocycle having a (meth)acryloyl group-containing monomer (b2) having a glass transition temperature of 0°C or higher A method for peeling a polarizing film with an adhesive layer containing 0.1 to 20% by weight of at least one high Tg monomer (B) selected from the group. The (meth)acrylic-based 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) A peeling method of a polarizing film provided with a pressure-sensitive adhesive layer containing a polar monomer other than b2). The method of claim 3, wherein the nitrogen-containing monomer is a vinyl-based monomer having a lactam ring. The method of claim 4, wherein the vinyl-based monomer having a lactam ring is a vinylpyrrolidone-based monomer. The method of 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 according to any one of claims 1 to 10, wherein the pressure-sensitive adhesive layer contains 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. , Peeling method of the polarizing film provided with the pressure-sensitive adhesive layer. The method according to claim 11, wherein the content of the silane coupling agent is 0.01 to 3 parts by weight based on 100 parts by weight of the (meth)acrylic polymer. It is a polarizing film provided with a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer on one side of the polarizing film,
The polarizing film provided with the pressure-sensitive adhesive layer includes a single-protection polarizing film having a protective film on only one side of the polarizer, and a single-protection polarizing film having a pressure-sensitive adhesive layer having a pressure-sensitive adhesive layer directly on the polarizer side of the single-protective polarizing film or through a coating layer. Is a film,
The pressure-sensitive adhesive layer is a polarizing film with a pressure-sensitive adhesive layer, characterized in that the adhesive force to the glass substrate decreases by contact with water and then increases. The polarizing film according to claim 13, wherein the pressure-sensitive adhesive layer has an initial adhesive strength of 2 to 10N/25mm to the glass substrate. The pressure-sensitive adhesive layer according to claim 13 or 14, wherein the adhesive force to the glass substrate after contacting with water decreases by 60% or more with respect to the initial adhesive force, becomes a minimum value, and then increases to 40% or more of the initial adhesive force. The polarizing film provided with the pressure-sensitive adhesive layer to become. The method according to any one of claims 13 to 15, wherein the pressure-sensitive adhesive layer contains a (meth)acrylic polymer as a base polymer,
The (meth)acrylic polymer is a monomer unit,
50% by weight or more of an alkyl (meth)acrylate (A) having a homopolymer having a glass transition temperature of less than 0°C, and
Consisting of an alkyl (meth)acrylate (b1) having a homopolymer having a glass transition temperature of 0°C or higher, and a monomer having a heterocycle having a (meth)acryloyl group-containing monomer (b2) having a glass transition temperature of 0°C or higher A polarizing film with a pressure-sensitive adhesive layer containing 0.1 to 20% by weight of at least one high Tg monomer (B) selected from the group. The method of claim 16, wherein the (meth)acrylic polymer 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 as a monomer unit, and the (meth)acryloyl group-containing monomer ( The polarizing film provided with the pressure-sensitive adhesive layer containing a polar monomer other than b2). The polarizing film according to claim 17, wherein the nitrogen-containing monomer is a vinyl-based monomer having a lactam ring. The polarizing film according to claim 18, wherein the vinyl-based monomer having a lactam ring is a vinylpyrrolidone-based monomer. The polarizing film according to claim 19, wherein the vinylpyrrolidone-based monomer is N-vinylpyrrolidone. The polarizing film with an adhesive layer according to any one of claims 17 to 20, wherein the (meth)acrylic polymer contains 0.1 to 5% by weight of the nitrogen-containing monomer as a monomer unit. The polarizing film with an adhesive layer according to any one of claims 17 to 21, wherein the (meth)acrylic polymer contains 0.01 to 3% by weight of the carboxyl group-containing monomer as a monomer unit. The polarizing film with an adhesive layer according to any one of claims 17 to 22, wherein the (meth)acrylic polymer contains 0.01 to 1% by weight of the hydroxyl group-containing monomer as a monomer unit. The polarizing film with an adhesive layer according to any one of claims 16 to 23, wherein the (meth)acrylic polymer has a weight average molecular weight of 900,000 or more. The method according to any one of claims 13 to 24, wherein the pressure-sensitive adhesive layer contains 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. , A polarizing film provided with an adhesive layer. The polarizing film with an adhesive layer according to claim 25, wherein the content of the silane coupling agent is 0.01 to 3 parts by weight based on 100 parts by weight of the (meth)acrylic polymer. An image display device having a polarizing film provided with the pressure-sensitive adhesive layer according to any one of claims 13 to 26.

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