JP5470048B2 - Polarizing plate having high modulus adhesive layer and image display apparatus using the same - Google Patents

Description

  The present invention relates to a polarizing plate used in an image display device such as a liquid crystal display device, and an image display device using the same.

  Conventionally, liquid crystal display devices have been used in desktop calculators, electronic timepieces, and the like, but their use has been rapidly expanding in recent years. That is, liquid crystal display devices have been used from mobile devices such as mobile phones to large televisions regardless of screen size. In addition to liquid crystal display devices, organic electroluminescence (organic EL) display devices also tend to increase mainly in mobile applications. The polarizing plates used in these image display apparatuses are not only in increasing demand but also required to have performance suitable for each application.

  The polarizing plate generally used in the image display apparatus as described above is a triacetyl cellulose film via a liquid adhesive on both sides of a polarizer in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin film. It is manufactured with the structure which laminated | stacked the transparent protective layer represented by. In this state, or if necessary, an image display such as a liquid crystal cell or an organic EL display element in a form in which various optical layers such as a retardation film and an optical compensation film having optical characteristics are bonded via an adhesive or an adhesive. An image display device is obtained by bonding to the element.

  FIG. 5 is a schematic cross-sectional view showing a general example in the case where such a conventional polarizing plate and a retardation film are laminated thereon. That is, the transparent protective layers 2 and 2 a are provided on both surfaces of the polarizer 1 to constitute the polarizing plate 16. In the case of distribution in this state, usually, an adhesive layer 8 for bonding to an image display element or the like is provided on at least one side (in the figure, transparent protective layer 2a side), and further to the image display element or the like on the outside thereof. A separate film (not shown) is provided to temporarily protect the surface until pasting. In addition, the retardation film 3 is bonded to the transparent protective layer 2a side of the polarizing plate 16 via the pressure-sensitive adhesive layer 8, and a pressure-sensitive adhesive layer 8a for bonding to an image display element or the like is further formed on the outside thereof. Provided and may be distributed as a polarizing plate 17 with a retardation film. In general, a separate film 9 is provided outside the pressure-sensitive adhesive layer 8a to temporarily protect the surface of the pressure-sensitive adhesive layer 8a until it is bonded to an image display element or the like.

  By the way, in recent years, in an image display device for mobile use such as a mobile phone, the whole module is being thinned and slimmed from the viewpoint of design and portability. As a matter of course, there is a demand for further reduction in thickness and weight of the polarizing plate used there. In addition, because of the wide variety of places of use due to the mobile use, there is a demand for durability that is higher than the conventional one while being thin and light.

  In order to meet the demands for thinning and weight reduction as described above, if the polarizer or the transparent protective layer of the polarizing plate is simply thinned, the polarizer has a characteristic that it is easy to tear in the stretching direction, and an adhesive is used. In the method of laminating a transparent protective layer, there is a limit to obtaining a thin and light polarizing plate from the viewpoint of handling at work. Further, in place of the configuration in which the transparent protective layers 2 and 2a are provided on both surfaces of the polarizer 1 as shown in FIG. 5, the transparent on the side to be bonded to another optical film such as the image display element or the retardation film 3 is used. The protective layer 2a is omitted, and a pressure-sensitive adhesive layer is provided directly on the polarizer 1, or another optical film such as a retardation film 3 is laminated via an adhesive or a pressure-sensitive adhesive to reduce the thickness of the polarizing plate. There are also attempts to do this. However, in this case, particularly when placed in a high temperature environment, there has been a problem that the dimensional change accompanying the expansion and contraction of the polarizer 1 becomes large and the durability is not always sufficient.

  On the other hand, the proposal which replaces the triacetyl cellulose film as a transparent protective layer with other resin is also made conventionally. For example, in JP-A-2000-199819 (Patent Document 1), a resin solution with a solvent that does not dissolve the film is applied to one or both sides of a polarizer made of a hydrophilic polymer to provide a transparent thin film layer. It is also disclosed that a protective layer made of a transparent film is disposed on the transparent thin film layer. Japanese Patent Application Laid-Open No. 2000-32430 (Patent Document 2) discloses that a cyclic olefin is formed on at least one surface of a polyvinyl alcohol polarizer through an adhesive composed of a mixture of a polyvinyl alcohol adhesive and a two-component adhesive. A polarizing plate in which a protective film made of a resin is laminated is disclosed. JP 2001-305345 A (Patent Document 3) discloses a protective film made of norbornene resin on at least one surface of a polarizer made of polyvinyl alcohol sheet with an aqueous polymer-isocyanate adhesive interposed therebetween. A laminated polarizing plate is disclosed.

  If the transparent film thru | or the cyclic olefin-type resin film (norbornene-type resin film also substantially synonymous) disclosed by these patent documents 1-3 is comprised with what has a function of retardation film, it will affix on an image display element. By reducing the number of members, a thin polarizing plate can be obtained. However, when an adhesive is used for laminating the polarizer and the transparent polymer film, the adhesive is applied to the polarizer and dried or cured, and then the polymer film is laminated. Since it is difficult to laminate the optical axis at a certain angle with respect to the axis of the polarizer, it is easy to form an elliptical or circular polarization mode polarizing plate that is particularly useful for image display devices for mobile applications. There is a problem to do.

  Furthermore, it is also known that the norbornene resin film as described above is bonded to a polarizer using an adhesive. For example, JP-A-6-511117 (Patent Document 4) discloses a polarizing plate in which a thermoplastic saturated norbornene resin film is laminated as a protective layer on at least one surface of a polarizer. In JP-A-8-43812 (Patent Document 5), in a polarizing plate in which protective films are laminated on both sides of a polarizer, at least one of the protective films has a function of a retardation film at the same time. As an example of a protective film having a retardation film function, a thermoplastic norbornene-based resin is cited. In these Patent Documents 4 and 5, as an adhesive used for laminating a polarizer and a norbornene resin film, natural rubber, synthetic rubber / elastomer, vinyl chloride / vinyl acetate copolymer, polyvinyl alkyl ether, polyacrylate, Examples thereof include modified polyolefin resin adhesives. However, both publications are limited to the description of the method for forming the pressure-sensitive adhesive layer or the method for laminating with the protective layer, and it can be said that the purpose of forming the thin polarizing plate is realized, but in terms of improving the durability, Specific adhesive properties or effects are not specified.

  In particular, as described above, a pressure-sensitive adhesive layer is directly provided on one side of a polarizer, and the pressure-sensitive adhesive layer is bonded to an image display element, or on one side of a polarizer, a retardation film or the like is interposed via a pressure-sensitive adhesive layer. When another optical film is laminated, an adhesive layer is provided on the outer side, and the outermost adhesive layer is bonded to the image display element, the polarizer shrinks when exposed to a high temperature environment. Along with this, the end of the polarizing plate swelled, and the screen display may be distorted. For this reason, in the field of mobile use polarizing plates that are reduced in thickness and weight by reducing the number of components, it is desired to maintain thin and good durability.

JP 2000-199819 A JP 2000-32430 A JP 2001-305345 A JP-A-6-511117 JP-A-8-43812

It is a cross-sectional schematic diagram which shows the example of the laminated constitution of the polarizing plate which concerns on one Embodiment of this invention. It is a cross-sectional schematic diagram which shows the example of the laminated constitution of the polarizing plate which concerns on another embodiment of this invention. It is a cross-sectional schematic diagram which shows the example which mounted | wore the liquid crystal panel with the polarizing plate of this invention. It is a graph which shows the swell state of the polarizing plate edge part after performing a durability test of 85 degreeC x 500 hours in the state which stuck the polarizing plate of the Example and the comparative example to the glass plate. It is a cross-sectional schematic diagram which shows the example of a layer structure about the conventional polarizing plate. It is explanatory drawing which shows the method of evaluating the light leak property of the polarizing plate with an adhesive obtained by the Example and the comparative example.

Explanation of symbols

1 …… Polarizer 2,2a …… Transparent protective layer 3 …… Polymer film (retardation film)
4. Other optical layers (surface treatment layers)
5. Other optical layers (such as brightness enhancement films)
6 …… Adhesive layer (high storage modulus)
7 …… Adhesive layer 8, 8a …… Adhesive layer (conventional)
9: Separator 10-13: Polarizing plate 16, 17 ... Polarizing plate (conventional)
20 …… Image display element (liquid crystal cell)

  An object of the present invention is to provide a polarizing plate in which a transparent protective layer is formed on one side of a polarizer and an adhesive layer is formed on the other side of the polarizer, and is bonded to an image display element via the adhesive layer. Alternatively, a transparent protective layer is formed on one side of the polarizer, and on the other side of the polarizer, an adhesive layer, a transparent polymer film, and an adhesive layer are formed in this order, with the outermost adhesive layer interposed therebetween. The polarizing plate that is bonded to the image display element gives good durability even in a high-temperature environment, especially when it is bonded to the image display element and exposed to a high-temperature environment. It is to suppress the climax and light leakage that are easy to do. Another object of the present invention is to apply this polarizing plate to an image display device.

  In order to achieve the above object, the polarizing plate of the present invention has a transparent protective layer formed on one side of a polarizer made of a polyvinyl alcohol-based resin film, and an adhesive layer is formed on the other side of the polarizer, Alternatively, the pressure-sensitive adhesive layer, the transparent polymer film, and the pressure-sensitive adhesive layer are formed in this order, and are bonded to the image display element through the outermost pressure-sensitive adhesive layer, and are bonded to the image display element. A layer is comprised by what shows the storage elastic modulus of 0.15-10 MPa in 23-80 degreeC. By providing such a hard pressure-sensitive adhesive layer exhibiting a high storage modulus on the surface to be bonded to the image display element, it is possible to impart good durability under a high temperature environment, and the image display element Even when exposed to a high temperature environment in a state of being bonded to the glass that constitutes, it is possible to suppress the rise of the end of the polarizing plate and light leakage due to the contraction of the polarizer.

  In this polarizing plate, the thickness of the pressure-sensitive adhesive layer bonded to the image display element is preferably 3 to 25 μm. Furthermore, the pressure-sensitive adhesive layer has removability, and it is preferable that a separate film treated with a release agent such as silicone is present on the exposed surface.

  As described above, in the polarizing plate of the present invention, a transparent protective layer is provided on one side of the polarizer, and an adhesive layer is provided on the other side of the polarizer, and the adhesive layer is bonded to the image display element. Alternatively, on the other surface of the polarizer, a pressure-sensitive adhesive layer, a transparent polymer film and a pressure-sensitive adhesive layer are provided in this order, and the outer pressure-sensitive adhesive layer is bonded to the image display element. The configuration is effective. In this case, the transparent polymer film is composed of a film having an in-plane retardation, and by combining the functions of a protective layer and a retardation film, it is possible to obtain a polarizing plate that is thin and lightweight by reducing the number of members. it can. Moreover, it can be set as the thin polarizing plate of an ellipse or a circularly polarized light mode by this.

  In these polarizing plates, an optical layer exhibiting another optical function can be further laminated on the transparent protective layer. For example, when this polarizing plate is disposed on the display surface (viewing side) of the image display element, a surface treatment layer such as a hard coat layer, an antireflection layer, or an antiglare layer may be provided on the transparent protective layer. it can. When this polarizing plate is disposed on the side opposite to the display surface of the liquid crystal cell (rear side), a reflective plate or a transflective plate is laminated on the transparent protective layer to provide a reflective or transflective reflector. A thin polarizing plate can be obtained, or a brightness enhancement film can be attached to form a thin polarizing plate that can be used for a brightness enhancement system.

  The polarizing plate of the present invention is constituted as described above, and when placed in an 85 ° C. dry heat environment with the outermost pressure-sensitive adhesive layer attached to glass for 500 hours, the polarizing plate has an inner side from the end of the polarizing plate. The raised height generated at a portion within 2 mm can be made 2 μm or less, and the light leakage is low even under predetermined conditions described later.

  The image display device of the present invention includes an image display element such as a liquid crystal cell or an organic EL display element, and any one of the above polarizing plates. In this image display device, the pressure-sensitive adhesive layer on the outermost side of the polarizing plate is bonded to the image display element.

In the polarizing plate of the present invention, a transparent protective layer is formed on one side of a polarizer, and an adhesive layer having a predetermined storage modulus at 23 to 80 ° C. is formed on the other side of the polarizer. The adhesive layer, the polymer film (for example, retardation film), and a predetermined storage elastic modulus at 23 to 80 ° C. are provided on the other surface of the polarizer or the other surface of the polarizer. The pressure-sensitive adhesive layers are formed in this order, and are bonded to the image display element via the outermost pressure-sensitive adhesive layer. In this way, by forming the adhesive layer directly on one side of the polarizer, the number of films to be bonded to the image display element is reduced, and the structure is made thinner and lighter and is bonded to the image display element. By constituting the pressure-sensitive adhesive layer with a hard material having a predetermined storage elastic modulus, good durability is exhibited even in a high temperature environment.
In addition, this polarizing plate has a hard adhesive layer side bonded to an image display device such as a liquid crystal cell or an organic EL display device, and is exposed to a high temperature environment even when exposed to a high temperature environment. The swell of the portion is suppressed, and the light leakage prevention property that can suppress light leakage is excellent. Therefore, an image display device in which this polarizing plate is combined with an image display element is also thinned and has excellent durability.

Hereinafter, the present invention will be described in detail with appropriate reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view illustrating an example of a layer configuration of a polarizing plate according to an embodiment of the present invention. With reference to FIG. 1, a polarizing plate 10 according to this embodiment has a transparent protective layer 2 formed on one side of a polarizer 1 and an adhesive layer 6 provided on the other side of the polarizer 1. And the adhesive layer 6 is comprised with what shows the storage elastic modulus of 0.15-10 MPa in 23-80 degreeC, Preferably it is 0.3-10 MPa in 23-80 degreeC. It is customary to place a separate film 9 on the exposed surface of the pressure-sensitive adhesive layer 6 and temporarily protect the surface until it is bonded to another member.

  FIG. 2 is a schematic cross-sectional view showing an example of a layer structure of a polarizing plate according to another embodiment of the present invention. With reference to FIG. 2, a polarizing plate 11 according to this embodiment forms a transparent protective layer 2 on one side of a polarizer 1, and an adhesive layer 7 and a transparent polymer film 3 on the other side of the polarizer 1. , And the pressure-sensitive adhesive layer 6 are provided in this order. And the adhesive layer 6 is comprised with what shows the storage elastic modulus of 0.15-10 MPa in 23-80 degreeC, Preferably it is 0.3-10 MPa in 23-80 degreeC. In this case as well, it is usual to place a separate film 9 on the exposed surface of the pressure-sensitive adhesive layer 6 and protect the surface temporarily until it is bonded to another member.

  The phrase “showing a storage elastic modulus of 0.15 to 10 MPa in the temperature range of 23 to 80 ° C.” means that the storage elastic modulus takes a value in the above range at any temperature within this range. Since the storage elastic modulus usually decreases gradually as the temperature rises, if both the storage elastic modulus at 23 ° C. and 80 ° C. are within the above range, the storage elastic modulus in the above range is exhibited at the temperature in this range. You can see. The above “shows a storage elastic modulus of 0.3 to 10 MPa at 23 to 80 ° C.” is the same as above.

[Polarizer]
The polarizer 1 is a film having a function of extracting linearly polarized light from incident natural light, and a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film can be used. The polyvinyl alcohol resin constituting the polarizer 1 can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes may be used. Moreover, the polymerization degree of polyvinyl alcohol-type resin is about 1,000-10,000 normally, Preferably it is about 1,500-5,000.

  A film obtained by forming such a polyvinyl alcohol-based resin is used as an original film of the polarizer 1. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. Although the film thickness of the raw film which consists of polyvinyl alcohol-type resin is not specifically limited, For example, it is about 1 micrometer-150 micrometers. Considering easiness of stretching, the film thickness is preferably 10 μm or more.

  The polarizer 1 has a step of uniaxially stretching such a polyvinyl alcohol resin film, a step of dyeing the polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, and a dichroic dye being adsorbed. It is manufactured through a step of treating the polyvinyl alcohol-based resin film with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution. As the dichroic dye, iodine or a dichroic organic dye is used.

[Transparent protective layer]
The transparent protective layer 2 provided on one side of the polarizer 1 can be composed of an appropriate transparent film. Among them, a film made of a resin excellent in transparency, optical property uniformity, mechanical strength, thermal stability, etc. is preferably used. For example, cellulose resin films such as triacetyl cellulose and diacetyl cellulose, polyester resin films such as polyethylene terephthalate and polyethylene isophthalate, polybutylene terephthalate, acrylic resin films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate, Examples thereof include a polycarbonate resin film, a polyethersulfone resin film, a polysulfone resin film, a polyimide resin film, a polyolefin resin film, and a cyclic olefin resin film having a cyclic olefin as a monomer such as norbornene. An adhesive or a pressure-sensitive adhesive can be used for adhesion between the transparent protective layer 2 and the polarizer 1.

[Polymer film or retardation film]
The polymer film 3 used in the form shown in FIG. 2 can be composed of various resins exemplified as the resin constituting the transparent protective layer 2. In particular, it is advantageous that the polymer film 3 has an in-plane retardation and has a function as a retardation film. The polymer film 3 having an in-plane retardation is preferably selected to have characteristics required as a retardation film, that is, its birefringence is optically uniform, and depends on the protective function of the polarizer 1 and the liquid crystal panel. It is used for the purpose of compensation of phase difference (including the meaning of viewing angle compensation). For example, those that have been used in image display devices can be used without limitation, birefringent films made of stretched films of various transparent polymers, films in which discotic liquid crystals and nematic liquid crystals are oriented and fixed. And those having the above-mentioned liquid crystal layer formed on a film substrate. When the liquid crystal layer is fixed on the film substrate, a cellulose resin film such as triacetyl cellulose is preferably used as the film substrate for supporting the oriented liquid crystal layer.

  Examples of the polymer forming the birefringent film include, for example, polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polyolefin such as polypropylene, polyarylate, polyamide, and cyclic olefin such as norbornene. And cyclic polyolefins. The stretched film may be processed by an appropriate method such as uniaxial or biaxial. Moreover, the birefringent film which controlled the refractive index of the thickness direction of a film by applying shrinkage force and / or extending | stretching force under adhesion | attachment with a heat-shrinkable film can also be used.

  In particular, in the case of an elliptically or circularly polarizing plate used in an image display device for mobile use, a 1 / 2λ plate or a 1 / 4λ plate is effectively used. The polarizing plate in the elliptical polarization mode or the circular polarization mode has a function of changing the incident polarized light to elliptically polarized light or circularly polarized light when the polarized light is linearly polarized light, and changing it to linearly polarized light when the incident polarized light is elliptically polarized light or circularly polarized light. doing. In particular, as a retardation film capable of changing elliptically polarized light or circularly polarized light into linearly polarized light and linearly polarized light into elliptically polarized light or circularly polarized light, a phase difference of 1/4 wavelength with respect to the wavelength of incident light, called a 1 / 4λ plate, is used. What is shown is used. The 1 / 2λ plate has a function of changing the direction of linearly polarized light. Furthermore, a 1 / 2λ plate and a 1 / 4λ plate are laminated so that the optical axes intersect at a predetermined angle to form a broadband 1 / 4λ plate that exhibits a 1/4 wavelength phase difference over a wide wavelength range. You can also.

  The elliptically polarizing mode polarizing plate is effective for preventing a coloring phenomenon caused by liquid crystal birefringence in a liquid crystal display device. The circularly polarizing mode polarizing plate is a reflective or transflective liquid crystal display device. Is effectively used for the purpose of improving the luminance. The circularly polarizing mode polarizing plate also has an antireflection function.

[Adhesive layer]
1 and 2, the pressure-sensitive adhesive layer 6 is arranged on the outermost side of the polarizing plate and is bonded to the image display element. In FIG. 2, the pressure-sensitive adhesive layer that bonds the polarizer 1 and the polymer film 3 together. 7 can be formed on the basis of various adhesives conventionally used for image display devices. For example, those having a base polymer such as acrylic, rubber, urethane, silicone, and polyvinyl ether are used. Moreover, an energy beam curing type, a thermosetting type, etc. may be sufficient. Among these, a pressure-sensitive adhesive having an acrylic resin excellent in transparency, weather resistance, heat resistance and the like as a base polymer is preferable.

[Adhesive 1 for polarizing plate]
As the above-mentioned adhesive, it adheres with good durability and hardly leaks light when applied to an image display device (liquid crystal display device) in a high temperature and high humidity environment. From the viewpoint of obtaining excellent removability to enable removability, (A1) an acrylic polymer having a weight average molecular weight of 1 million or more, wherein the monomer containing a hydroxyl group is 10% by mass or less, (B1) carboxyl A monomer containing a group includes an acrylic polymer having a weight average molecular weight of 1 million or more and a (C) active energy ray-curable compound having a monomer composition ratio of 10% by mass or less, and a component (A1), a component (B1), The pressure-sensitive adhesive for polarizing plate 1 is preferably obtained by irradiating an adhesive material having a mass ratio of 100: 1 to 100: 50 (hereinafter sometimes referred to as adhesive material 1) with active energy rays. And the like.

(A1) As an acrylic polymer of a component, a (meth) acrylic acid ester polymer can be mentioned preferably. In the present invention, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms.
Usually, in order to crosslink a (meth) acrylic acid ester polymer and impart durability to the pressure-sensitive adhesive, a (meth) acrylic acid ester monomer having a functional group serving as a crosslinking point does not have a functional group (meth) A (meth) acrylic acid ester copolymer is obtained by copolymerizing with an acrylic acid ester monomer, and this is used as the main component of the pressure-sensitive adhesive. In the component (A1), a hydroxyl group serves as a crosslinking point.

  Specific examples of the monomer containing a hydroxyl group in the component (A1) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) acrylic. (Meth) acrylic acid hydroxyalkyl esters such as 2-hydroxybutyl acid, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like, among them, (meth) acrylic acid 2 -Hydroxyethyl and 4-hydroxybutyl (meth) acrylate are preferred from the viewpoint that a (meth) acrylic acid polymer having a weight average molecular weight of 1,000,000 or more can be easily produced.

There is no restriction | limiting in particular as a (meth) acrylic acid ester monomer which does not have a functional group, For example, the C1-C20 (meth) acrylic acid ester whose alkyl group of an ester part can mention preferably. Here, examples of the (meth) acrylic acid ester having 1 to 20 carbon atoms of the alkyl group in the ester portion include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth ) Butyl acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, ( Examples include dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.
Among these compounds, in particular, butyl (meth) acrylate can obtain an appropriate pressure-sensitive adhesive performance, and can easily produce a (meth) acrylate polymer having a weight average molecular weight of 1 million or more. preferable.

The component (A1) is characterized in that the monomer containing a hydroxyl group is 10% by mass or less in terms of the monomer composition ratio. When the monomer containing a hydroxyl group exceeds 10% by mass, the durability at high temperature and high humidity becomes insufficient. From the above points, the content of the monomer containing a hydroxyl group is preferably 7% by mass or less, more preferably 5% by mass or less.
On the other hand, the lower limit of the monomer containing a hydroxyl group is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more from the viewpoint of durability at high temperatures.

The acrylic polymer as the component (A1) needs to have a weight average molecular weight of 1 million or more. When the weight average molecular weight is less than 1,000,000, adhesion to adherends such as polarizers, polymer films (for example, retardation films) or liquid crystal cells, and adhesion under high temperature and high humidity. Durability may be insufficient, and floating or peeling may occur. In view of adhesion and adhesion durability, the weight average molecular weight is preferably 1.2 million to 2,200,000, particularly preferably 1,500,000 to 2,000,000. Further, the molecular weight distribution (Mw / Mn) representing the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 20 or less. When the molecular weight distribution is 20 or less, sufficient adhesion durability can be obtained. In addition, the said weight average molecular weight and number average molecular weight are the values of polystyrene conversion measured by the gel permeation chromatography (GPC) method.
In the adhesive material 1, the acrylic polymer of the component (A1) may be used alone or in combination of two or more.

  Next, as the acrylic polymer of the component (B1), a (meth) acrylic acid ester polymer can be preferably exemplified as in the case of the component (A1). Also in the acrylic polymer of the component (B1), in the same manner as the component (A1), in order to impart durability to the pressure-sensitive adhesive, usually, a (meth) acrylic acid ester monomer and a functional group having a functional group serving as a crosslinking point. Copolymers with (meth) acrylic acid ester monomers that do not contain In the component (B1), the carboxyl group serves as a crosslinking point.

  Specific examples of the monomer containing a carboxyl group in the component (B1) include (meth) acrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid and the like, and a (meth) acryl having a weight average molecular weight of 1 million or more. (Meth) acrylic acid is preferred because an acid ester copolymer can be easily produced.

There is no restriction | limiting in particular as (meth) acrylic acid ester monomer which does not have a functional group in (B1) component, The carbon number of the alkyl group of the ester part is the same as that used by (A1) component, ie, 1-20. The (meth) acrylic acid ester can be preferably mentioned. These may be used alone or in combination of two or more.
Among these compounds, as in the case of the component (A1), butyl (meth) acrylate, in particular, can obtain an appropriate adhesive performance, and is a (meth) acrylic acid ester polymer having a weight average molecular weight of 1 million or more. Is preferable in that it can be easily produced.

The component (B1) is characterized in that the monomer containing a carboxyl group is 10% by mass or less in terms of the monomer composition ratio. When the monomer containing a carboxyl group exceeds 10% by mass, durability at high temperature and high humidity becomes insufficient. From the above points, the content of the monomer containing a carboxyl group is preferably 8% by mass or less, and more preferably 5% by mass or less.
On the other hand, the lower limit of the monomer containing a carboxyl group is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more from the viewpoint of durability at high temperatures.

The acrylic polymer as the component (B1) needs to have a weight average molecular weight of 1 million or more. When the weight average molecular weight is less than 1,000,000, the adhesion with the adherend and adhesion durability under high temperature and high humidity are poor as in the case where the weight average molecular weight of the component (A1) is less than 1,000,000. It may be sufficient to cause floating or peeling. Considering adhesion and adhesion durability, the weight average molecular weight is preferably 1,200,000 to 2,200,000, particularly preferably 1,500,000 to 2,000,000, as in the case of component (A1). Further, the molecular weight distribution (Mw / Mn) representing the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 20 or less. When the molecular weight distribution is 20 or less, sufficient adhesion durability can be obtained.
In the adhesive material 1, the acrylic polymer of the component (B1) may be used alone or in combination of two or more.

  In the adhesive material 1, it is preferable that mass ratio ((A1) component: (B1) component) of said (A1) component and (B1) component is the range of 100: 1-100: 50. Adequate adhesion durability even when severe durability is required when the mass ratio is 100: 1 or more, that is, the content of the component (B1) is 1 part by mass or more with respect to 100 parts by mass of the component (A1). Is obtained. On the other hand, when the said mass ratio is 100: 50 or less, ie, content of (B1) component is 50 mass parts or less with respect to 100 mass parts of (A1) component, it is preferable at the point of removability.

  The (meth) acrylic acid ester polymer may contain a copolymerizable component as a constituent component as long as the effects of the present invention are not impaired. Specifically, it is a monomer containing an amide group, an amino group or the like as a functional group, and more specific examples include acrylamides such as (meth) acrylamide, N-methyl (meth) acrylamide, and N-methylol (meth) acrylamide. (Meth) acrylic acid monomethylaminoethyl, (meth) acrylic acid monoethylaminoethyl, (meth) acrylic acid monomethylaminopropyl, (meth) acrylic acid monoethylaminopropyl (meth) acrylic acid monoalkylamino esters Etc. These monomers may be used independently and may be used in combination of 2 or more type.

In the adhesive material 1, as the active energy ray-curable compound used as the component (C), a polyfunctional (meth) acrylate monomer having a molecular weight of less than 1000 can be preferably exemplified.
Examples of the polyfunctional (meth) acrylate monomer having a molecular weight of less than 1000 include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, Polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate , Ethylene oxide-modified phosphoric acid di (meth) acrylate, di (meth) acryloxyethyl isocyanurate, allylated cyclohexyl di (meth) acrylate, tricyclodecane dimethanol (meth) a Relate, dimethylol dicyclopentane di (meth) acrylate, ethylene oxide modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl glycol modified trimethylolpropane di (meth) acrylate, adamantane Bifunctional type such as di (meth) acrylate, 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene; trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid Modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (meth) Trifunctional type such as acryloxyethyl isocyanurate; tetrafunctional type such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; pentafunctional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate; Examples thereof include hexafunctional types such as pentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate.

  These polyfunctional (meth) acrylate monomers may be used alone or in combination of two or more, but among these, those having a cyclic structure in the skeleton structure are included. It is preferable to do. The cyclic structure may be a carbocyclic structure or a heterocyclic structure, and may be a monocyclic structure or a polycyclic structure. Examples of such polyfunctional (meth) acrylate monomers include those having an isocyanurate structure such as di (meth) acryloxyethyl isocyanurate, tris (meth) acryloxyethyl isocyanurate, dimethylol dicyclopentane di ( Suitable are meth) acrylate, ethylene oxide modified hexahydrophthalic acid di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, neopentyl glycol modified trimethylolpropane di (meth) acrylate, adamantane di (meth) acrylate, etc. In particular, those having an isocyanurate structure are preferred.

  Further, an active energy ray-curable acrylate oligomer can be used as the component (C). The acrylate oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylate oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate.

Examples of the polyester acrylate oligomer include esterification of a hydroxyl group of a polyester oligomer having a hydroxyl group at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid, or a polyvalent carboxylic acid. It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to an acid with (meth) acrylic acid. The epoxy acrylate oligomer can be obtained, for example, by reacting (meth) acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolak type epoxy resin and esterifying it. A carboxyl-modified epoxy acrylate oligomer obtained by partially modifying this epoxy acrylate oligomer with a dibasic carboxylic acid anhydride can also be used. The urethane acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by the reaction of polyether polyol or polyester polyol and polyisocyanate with (meth) acrylic acid. It can be obtained by esterifying the hydroxyl group of ether polyol with (meth) acrylic acid.
The weight average molecular weight of the acrylate oligomer is a value in terms of standard polystyrene measured by the GPC method, and is preferably 50,000 or less, more preferably 500 to 50,000, still more preferably 3,000 to 40, as described above. , 000 is selected.
These acrylate oligomers may be used alone or in combination of two or more.

In the present invention, an adduct acrylate polymer in which a group having a (meth) acryloyl group is introduced into the side chain can also be used as the component (C). Such an adduct acrylate polymer is, for example, a copolymer of the (meth) acrylic acid ester described in the above-described (meth) acrylic acid ester polymer of the component (A1) and a monomer having a functional group in the molecule. And a compound having a (meth) acryloyl group and a group that reacts with the functional group is reacted with a part of the functional group of the copolymer. The weight average molecular weight of the adduct acrylate polymer is usually 500,000 to 2,000,000 in terms of polystyrene.
In the present invention, as the component (C), one type may be appropriately selected from the above polyfunctional acrylate monomers, acrylate oligomers, and adduct acrylate polymers, or two or more types may be used in combination. Good.

  The content ratio of the active energy ray-curable compound of the component (C) is a mass ratio ((A1) component: (C) in terms of the performance of the pressure-sensitive adhesive obtained with respect to the acrylic polymer of the component (A1). ) Component) is preferably 100: 1 to 100: 100, more preferably 100: 5 to 100: 50, and still more preferably 100: 10 to 100: 40.

  The adhesive material 1 can contain a photopolymerization initiator as desired. Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl]- 2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethyla Nobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone], 2 , 4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and the like. These may be used individually by 1 type, may be used in combination of 2 or more types, and the compounding quantity is 0.2-20 mass normally with respect to 100 mass parts of said (C) component. Selected in the range of parts.

  If desired, the adhesive material 1 can contain a crosslinking agent as the component (D). There is no restriction | limiting in particular as this crosslinking agent, Arbitrary things can be suitably selected and used from what was conventionally used as a crosslinking agent in an acrylic adhesive. Examples of such crosslinking agents include polyisocyanate compounds, epoxy resins, melamine resins, urea resins, dialdehydes, methylol polymers, aziridine compounds, metal chelate compounds, metal alkoxides, and metal salts. A compound is preferably used.

  Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, and the like. Examples thereof include biurets, isocyanurates, and adducts that are a reaction product with a low-molecular active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil.

  The said crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, although the usage-amount is based also on the kind of crosslinking agent, it is 0.01-20 mass parts normally with respect to 100 mass parts of acrylic polymers of the said (A1) component, Preferably, it is 0.1-10 mass. Part.

  If desired, the adhesive material 1 can contain a silane coupling agent as the component (E). By including this silane coupling agent, the adhesion between the pressure-sensitive adhesive and the liquid crystal cell becomes better when the polarizing plate is bonded to, for example, a liquid crystal cell. This silane coupling agent is an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the pressure-sensitive adhesive component, and having light transparency, for example, substantially transparent Is preferred. The addition amount of such a silane coupling agent is 0.001-10 mass with respect to 100 mass parts of solid content of adhesive material 1 (Total amount of (A1) component, (B1) component, and (C) component). The range of parts is preferable, and the range of 0.005 to 5 parts by mass is particularly preferable.

  Specific examples of the silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and 3-methacryloxypropyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, Silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- Amino group-containing silicon compounds such as (2-aminoethyl) -3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.

[Plastic adhesive 2]
As an adhesive, it adheres with good durability, prevents light leakage when applied to an image display device (liquid crystal display device) in a high-temperature and high-humidity environment, and can be easily re-applied in the event of incorrect bonding. From the viewpoint of obtaining excellent removability to enable peeling, hydroxyl group-containing monomers 0 to 5 are included in the monomer that comprises (A2) an acrylic polymer and (C) an active energy ray-curable compound and constitutes component (A2). A polarizing plate formed by irradiating an adhesive material containing 0.05% by mass and a carboxyl group-containing monomer of 0.05% by mass or more and less than 1.0% by mass with an active energy ray (hereinafter sometimes referred to as adhesive material 2). The pressure-sensitive adhesive 2 for use is also preferred. Since the polarizing plate adhesive 2 does not need to be blended with different acrylic polymers like the polarizing plate adhesive 1, it is excellent in terms of productivity, economy, etc. in addition to stability as an adhesive. And is more preferably used as a pressure-sensitive adhesive for polarizing plates in the present invention.

  As the acrylic polymer as the component (A2), a (meth) acrylic acid ester polymer can be preferably exemplified. Usually, in order to crosslink a (meth) acrylic acid ester polymer and impart durability to the pressure-sensitive adhesive, a (meth) acrylic acid ester monomer having a functional group serving as a crosslinking point does not have a functional group (meth) A (meth) acrylic acid ester copolymer is obtained by copolymerizing with an acrylic acid ester monomer, and this is used as the main component of the pressure-sensitive adhesive. In the component (A2), a carboxyl group or a hydroxyl group and a carboxyl group serve as a crosslinking point.

  The monomer containing a hydroxyl group and the (meth) acrylic acid ester monomer having no functional group in the component (A2) are the same as those of the pressure-sensitive adhesive for polarizing plate 1, and the monomer containing a carboxyl group is (meth) Examples include acrylic acid, maleic acid, itaconic acid, citraconic acid, and fumaric acid.

The component (A2) is characterized in that the monomer containing a hydroxyl group contains 0 to 5% by mass of the monomer composition ratio and 0.05% by mass or more and less than 1.0% by mass of the carboxyl group-containing monomer.
When the monomer containing a hydroxyl group is 5% by mass or less, durability at high temperature and high humidity is sufficient. On the other hand, the lower limit of the monomer containing a hydroxyl group is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, from the viewpoint of durability at high temperatures. It is preferable that
Further, when the carboxyl group-containing monomer is 0.05% by mass or more, durability at high temperatures is secured, and when it is less than 1.0% by mass, removability can be secured. The content of the carboxyl group-containing monomer in the component (A2) is preferably 0.05 to 0.9% by mass, more preferably 0.05 to 0.7% by mass.

  The acrylic polymer as the component (A2) preferably has a weight average molecular weight of 500,000 or more. When the weight average molecular weight is 500,000 or more, adhesion to an adherend such as a polarizer, a polymer film (for example, a retardation film) or an image display element such as a liquid crystal cell, and adhesion under high temperature and high humidity. Durability is sufficient and there is no risk of lifting or peeling. In consideration of adhesion and adhesion durability, the weight average molecular weight is preferably 600,000 to 2,000,000, more preferably 1,200,000 to 2,000,000, and particularly preferably 1,500,000 to 2,000,000. Further, the molecular weight distribution (Mw / Mn) representing the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 20 or less. When the molecular weight distribution is 20 or less, sufficient adhesion durability can be obtained. In addition, the said weight average molecular weight and number average molecular weight are the values of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  As the acrylic polymer as the component (A2), one type may be used alone, or two or more types may be used in combination. Further, the acrylic polymer of the component (A2) may contain a copolymerizable component as a constituent component as long as the effects of the present invention are not impaired. It is the same as the component described in the component.

  The adhesive material 2 can contain an active energy ray-curable compound as the component (C). The active energy ray-curable compound of the component (C) used here is the same as the active energy ray-curable compound of the component (C) used for the adhesive material 1 described above. In addition, the content ratio of the active energy ray-curable compound of the component (C) is a mass ratio ((A) component: ((A)) from the aspect of the performance of the obtained adhesive with respect to the acrylic polymer of the component (A2). In the component (B), 100: 1 to 100: 100 is preferable, more preferably 100: 5 to 100: 50, and still more preferably 100: 10 to 100: 40.

  The adhesive material 2 can contain a photopolymerization initiator as desired. The photopolymerization initiator is the same as the photopolymerization initiator contained in the adhesive material 1. Moreover, the compounding quantity of the said photoinitiator is normally chosen in the range of 0.2-20 mass parts with respect to 100 mass parts of (C) component.

  If desired, the adhesive material 2 can contain a crosslinking agent as the component (D). The crosslinking agent is the same as the crosslinking agent contained in the adhesive material 1. Moreover, although the usage-amount of the said crosslinking agent is based also on the kind of crosslinking agent, it is 0.01-20 mass parts normally with respect to 100 mass parts of acrylic polymers of (A2) component, Preferably it is 0.1-10. Part by mass.

  If desired, the adhesive material 2 can contain a silane coupling agent as the component (E). The silane coupling agent is the same as the silane coupling agent contained in the adhesive material 1. Moreover, the addition amount of the said silane coupling agent is the range of 0.001-10 mass parts normally with respect to 100 mass parts of solid content of the adhesive material 2 ((A2) component and the total amount of (C) component). Is preferable, and the range of 0.005 to 5 parts by mass is particularly preferable.

  The polarizing plate adhesives 1 and 2 are obtained by irradiating the adhesive materials 1 and 2 thus obtained with active energy rays.

Examples of the active energy rays include ultraviolet rays and electron beams. The ultraviolet rays are obtained with a high-pressure mercury lamp, an electrodeless lamp, a xenon lamp or the like, while the electron beam is obtained with an electron beam accelerator or the like. Among these active energy rays, ultraviolet rays are particularly preferable. In addition, when using an electron beam, an adhesive can be formed, without adding a photoinitiator.
The irradiation amount of the active energy ray for the adhesive material is appropriately selected so as to obtain a pressure-sensitive adhesive having a suitable storage elastic modulus and an adhesive strength to non-alkali glass. In the case of ultraviolet rays, an illuminance of 50 to 1000 mW / In the case of cm < ² >, light quantity 50-1000mJ / cm < ² >, and an electron beam, the range of 10-1000krad is preferable.

  In order to improve the adhesiveness between an adhesive layer and a polarizer or a polymer film (for example, retardation film), the adhesive material can contain an adhesiveness improving agent. Adhesion improvers include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, or active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane, castor oil, and the above-mentioned Examples thereof include polyisocyanate compounds such as adducts that are a reaction product with an aromatic polyisocyanate.

In the pressure-sensitive adhesives 1 and 2 for polarizing plates preferably used in the present invention, various additives usually used for acrylic pressure-sensitive adhesives as desired, for example, a tackifier, an oxidation, and the like, as long as the object of the present invention is not impaired. Inhibitors, light stabilizers, softeners, fillers and the like can be added.
In addition, the adhesive material itself can also be made into an adhesive layer, without irradiating an active energy ray to an adhesive material like the adhesive 1 and 2 for polarizing plates. When the adhesive material itself is used as an adhesive layer, various materials listed as those that can be added to the pressure-sensitive adhesives 1 and 2 for polarizing plates can be appropriately used.

[Storage modulus of adhesive layer]
In the polarizing plate of the present invention, the pressure-sensitive adhesive layer 6 disposed on the outermost side of the polarizing plate and bonded to the image display element is 0.15 to 10 MPa at 23 to 80 ° C., preferably 0.3 to 23 to 80 ° C. A material having a storage elastic modulus of 10 MPa, that is, a pressure-sensitive adhesive is made of a hard material (a material having a high storage elastic modulus). The storage elastic modulus (G ′) is a value measured according to JIS K7244.

  A pressure-sensitive adhesive used for a normal image display device or an optical film for the device has a storage elastic modulus of about 0.1 MPa at most, but compared with that, the storage elastic modulus of the pressure-sensitive adhesive layer 6 defined in the present invention is 0. .15 to 10 MPa is a high value. By using such a hard adhesive that exhibits a high storage elastic modulus, it becomes possible to suppress dimensional changes accompanying the contraction of the polarizer that occurs when placed in a high-temperature environment, and good durability is obtained. . In particular, when exposed to a high-temperature environment in a state of being bonded to the glass plate constituting the image display element via the outermost adhesive layer 6 of the polarizing plate, the end of the polarizing plate accompanies the contraction of the polarizer. It is possible to suppress the phenomenon that the part swells, and to further prevent light leakage.

  Means for increasing the storage elastic modulus of the pressure-sensitive adhesive layer 6 bonded to the image display element as described above is not particularly limited. For example, an ordinary pressure-sensitive adhesive composition as described above may include an oligomer, specifically It is effective to blend urethane acrylate oligomer. Preferably, such a urethane acrylate oligomer blended and then cured by irradiation with energy rays exhibits a high storage elastic modulus. A pressure-sensitive adhesive composition containing a urethane acrylate-based oligomer, or a film-like pressure-sensitive adhesive obtained by coating it on a support film and curing it with ultraviolet rays is known and can be obtained from a pressure-sensitive adhesive manufacturer.

  When the form shown in FIG. 2 is adopted, the pressure-sensitive adhesive layer 7 for bonding the polarizer 1 and the transparent polymer film 3 is composed of a material having a high storage elastic modulus similar to the pressure-sensitive adhesive layer 6 disposed on the outermost side. Alternatively, the pressure-sensitive adhesive layer 6 may be made of a pressure-sensitive adhesive having a general storage property lower than that of the pressure-sensitive adhesive layer 6. In consideration of suppressing the dimensional change accompanying the contraction of the polarizer, the pressure-sensitive adhesive layer 7 is preferably composed of a material having a high storage elastic modulus.

[Adhesive strength of adhesive layer]
The adhesive strength of the pressure-sensitive adhesive layer when sticking the polarizing plate and the alkali-free glass in the present invention is preferably 20 N / 25 mm or less even after 7 days have elapsed after bonding. When the adhesive strength is 20 N / 25 mm or less, re-peeling is possible without damaging the liquid crystal cell. Moreover, it is preferable that this adhesive force is the range of 0.2-20N / 25mm. If this adhesive strength is 0.2 N / 25 mm or more, the polarizing plate can be kept in a state of being bonded to, for example, a liquid crystal cell with sufficient adhesive strength.

Here, the said adhesive force is the value measured by the following method.
A 25 mm wide, 100 mm long sample was cut out from the polarizing plate with the pressure-sensitive adhesive layer, the release sheet was peeled off (thickness of the pressure-sensitive adhesive layer was 25 μm), and affixed to an alkali-free glass, and then 0.5 MPa, 50 ° C., 20 minutes. Pressurize under the following conditions. Then, after being left for 7 days in an environment of 23 ° C. and a relative humidity of 50%, the value measured using a tensile tester in the same environment under the conditions of a peeling rate of 300 mm / min and a peeling angle of 180 ° is the adhesive strength. It is.

[Other explanation about adhesive layer]
The pressure-sensitive adhesive layers 6 and 7 are formed, for example, by dissolving or dispersing the pressure-sensitive adhesive composition or the pressure-sensitive adhesive material as described above in an organic solvent such as toluene or ethyl acetate to prepare a solution having a concentration of 10 to 40% by mass. After this is applied directly to the surface of the film on which the pressure-sensitive adhesive layer is to be formed and dried (in the case of a pressure-sensitive material, it is further irradiated with active energy rays) and then a separate film made of a resin film. 9 or after forming a pressure-sensitive adhesive layer on the separate film 9 and transferring it to the surface of the film to be formed (in the case of an adhesive material, transfer to the surface of the film to be formed and then active energy rays Or the like.
Here, as a method for applying the pressure-sensitive adhesive composition or the pressure-sensitive adhesive material, conventionally known methods such as a roll coating method, a knife coating method, a bar coating method, a gravure coating method, a die coating method, and a spray coating method are applied. Is possible. Moreover, when forming an adhesive layer on a film, the process for improving adhesiveness to the surface (one side or both) on which the film and the adhesive layer are bonded together as necessary, for example, corona treatment Etc. may be given.

  The separate film 9 temporarily protects the surface of the pressure-sensitive adhesive layer 6 until the polarizing plates 10 and 11 are bonded to an image display element. For example, the separate film 9 is a film made of a transparent resin such as polyethylene terephthalate. Those subjected to treatment with a release agent such as silicone are used.

  The thickness of the pressure-sensitive adhesive layers 6 and 7 can usually be about 1 to 40 μm. In order to obtain a thin polarizing plate which is the object of the present invention, it is desirable to form the adhesive layers 6 and 7 thinly within a range not impairing properties such as workability and durability, for example, 3 to 25 μm. This is suitable for obtaining good durability while maintaining good processability.

[Other optical layers]
The polarizing plate of the present invention is configured as described above, and an optical layer having other optical functions can be laminated on the transparent protective layer 2 as necessary.

  For example, when this polarizing plate is disposed on the display surface (viewing side) of the image display element, a surface treatment layer such as a hard coat layer, an antireflection layer, or an antiglare layer is provided on the transparent protective layer. May be. The hard coat layer is formed to prevent scratches on the surface of the polarizing plate. The hard coat layer is mainly composed of an ultraviolet curable resin, for example, an acrylic resin or a silicone resin, and the adhesiveness to the transparent protective layer 2. Those having excellent hardness are appropriately selected and can be formed on the surface of the transparent protective layer 2.

  The antireflection layer is formed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be formed by a known method. The anti-glare layer is formed to prevent disturbance of visibility caused by external light reflected on the surface of the polarizing plate, for example, a roughening method such as a sand blast method or an embossing method, In general, the surface of the transparent protective layer 2 is formed to have a concavo-convex structure by, for example, a method of applying and curing a coating liquid in which transparent fine particles are mixed with an ultraviolet curable resin.

  On the other hand, when this polarizing plate is disposed on the opposite side (rear side) of the display surface of the liquid crystal cell, on the transparent protective layer 2, a reflective layer, a transflective layer, a light diffusing layer, a light collector, and a luminance improvement A film or the like can be laminated.

  The reflective polarizing plate is used in a liquid crystal display device of a type that reflects and displays external light incident from the viewing side. Since a light source such as a backlight can be omitted, the liquid crystal display device can be easily thinned. The transflective polarizing plate is used in a liquid crystal display device that displays as a reflective type in a bright place and as a transmissive type using a light source such as a backlight in a dark place. The reflective layer for making a reflective polarizing plate can be formed, for example, by attaching a foil or vapor deposition film made of a metal such as aluminum to the protective layer 4 on the polarizer 1. The semi-transmissive reflective layer for making a semi-transmissive reflective polarizing plate is a method of using the reflective layer as a half mirror, or a reflective plate containing a pearl pigment or the like and exhibiting light transmittance is adhered to the polarizing plate. It can be formed by a method or the like.

  The diffusion type polarizing plate has a function of diffusing incident light. For the light diffusion layer used for that purpose, various methods such as a method of performing a mat treatment on the transparent protective layer 4 on the polarizer 1, a method of applying a resin containing fine particles, and a method of adhering a film containing fine particles are used. Formed.

  Further, the reflection / diffusion polarizing plate is obtained by providing a diffusion reflection layer, for example, by providing a reflection layer reflecting the uneven structure on the fine uneven structure surface of the diffusion type polarizing plate. The reflective layer having a fine concavo-convex structure has advantages such that incident light is diffused by irregular reflection, directivity and glare can be prevented, and unevenness in brightness and darkness can be suppressed. In addition, the resin layer or film containing fine particles has an advantage that incident light and its reflected light are diffused when passing through the layer, and brightness unevenness can be further suppressed. The reflective layer reflecting the surface fine concavo-convex structure can be formed, for example, by directly attaching a metal to the surface of the fine concavo-convex structure by a method such as vapor deposition such as vacuum deposition, ion plating, sputtering, or plating. Examples of the fine particles to be blended for forming the surface fine concavo-convex structure include silica, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, cadmium oxide, and oxide having an average particle diameter of 0.1 to 30 μm. Inorganic fine particles made of antimony or the like, organic fine particles made of a crosslinked or uncrosslinked polymer, or the like can be used.

  The light collector is attached for the purpose of optical path control and can be formed as a prism array sheet, a lens array sheet, a dot attached sheet, or the like.

  The brightness enhancement film has a function of transmitting a part of incident natural light as linearly polarized light or circularly polarized light and reflecting the remaining light for reuse, and is used for the purpose of improving brightness in a liquid crystal display device or the like. . Examples include a reflective linearly polarized light separation sheet, a cholesteric liquid crystal polymer alignment film designed to produce anisotropy in reflectance by laminating a plurality of thin film films having different refractive index anisotropies, and the like. Examples include a reflective circularly polarized light separating sheet in which an oriented liquid crystal layer is supported on a film substrate.

  The various optical layers as described above can be integrated with the transparent protective layer 2 using a pressure-sensitive adhesive or an adhesive, but the pressure-sensitive adhesive or the adhesive used for this purpose is not particularly limited and may be appropriately selected. You can select and use one. It is preferable to use a pressure-sensitive adhesive from the viewpoint of simplicity of bonding work and prevention of optical distortion. As an example of an adhesive, the thing similar to having demonstrated the adhesive layers 6 and 7 previously with reference to FIG.1 and FIG.2 can be mentioned. Further, when the formed pressure-sensitive adhesive layer is exposed on the surface, a separate film is preferably disposed for preventing contamination. As a separate film, the thing similar to what was demonstrated previously can be used.

[Image display element]
The polarizing plate of this invention can be arrange | positioned at various image display elements, and can be set as an image display apparatus. For example, it can be arranged on one or both sides of a liquid crystal cell to provide a liquid crystal display device. The liquid crystal cell to be used is arbitrary, for example, VA (Vertical Alignment), IPS (In-plane Switching), ECB (Electrically Controlled Birefringence), OCB (Optically Compensated Birefringed type, etc.). Liquid crystal display devices using various liquid crystal panels such as a simple matrix drive type represented by STN (Super Twisted Nomadic) mode and a static drive type represented by TN (Twisted Nematic) mode Can be formed. When providing the polarizing plate of this invention in the both sides of a liquid crystal cell, both may be the same and may differ.

  In the IPS mode liquid crystal display device, in the viewing side polarizing plate, when there is a member having a retardation in the thickness direction between the polarizer and the liquid crystal cell, the color change from the oblique direction becomes large. Therefore, as shown in FIG. 1, if a configuration in which the pressure-sensitive adhesive layer 6 is provided on one surface of the polarizer 1 is adopted and directly bonded to the liquid crystal cell via the pressure-sensitive adhesive layer 6, a space between the polarizer and the liquid crystal cell is obtained. There is no retardation in the thickness direction. Therefore, the configuration shown in FIG. 1 is particularly effective for an IPS mode liquid crystal cell.

  In addition, in the VA, ECB, OCB, STN, and TN mode liquid crystal display devices, if there is no planar phase difference between the liquid crystal cell and the viewing side and / or the back side polarizer, the viewing angles on the top, bottom, left, and right are extremely high. It will become narrower. Therefore, as shown in FIG. 2, a configuration in which transparent protective layer 2 / polarizer 1 / adhesive layer 7 / polymer film 3 (particularly retardation film) / adhesive layer 6 is provided in this order is adopted. When bonded to the liquid crystal cell via the layer 6, the viewing angle can be increased. Therefore, the configuration shown in FIG. 2 is particularly effective for VA, ECB, OCB, STN, and TN mode liquid crystal cells, particularly VA mode liquid crystal cells.

  FIG. 3 is a schematic cross-sectional view showing an example in which the polarizing plate according to the present invention is mounted on a liquid crystal panel. In this example, basically, the polarizing plates 11 having the form shown in FIG. 2 are arranged on both surfaces of the liquid crystal cell 20. That is, the adhesive layer 6 / polymer film (retardation film) 3 / adhesive layer 7 / polarizer 1 / surface treatment layer 4 is provided on one side (upper side in the figure) of the liquid crystal cell 20 from the liquid crystal cell 20 side. Polarizing plate 12 laminated in the order of transparent protective layer 2 (surface treatment layer 4 is outside) (this is in a state where separate film 9 is peeled off from polarizing plate 11 shown in FIG. 2 except that surface treatment layer 4 is provided. Is equivalent). Further, on the other side of the liquid crystal cell 20 (the lower side of the figure), from the liquid crystal cell 20 side, the pressure-sensitive adhesive layer 6 / polymer film (retardation film) 3 / pressure-sensitive adhesive layer 7 / polarizer 1 / transparent protective layer. 2 / Polarizing plate 13 laminated in the order of other optical layer 5 (this corresponds to the state where the separate film 9 is peeled off from the polarizing plate 11 shown in FIG. 2 except that the other optical layer 5 is provided. Is attached). In the liquid crystal display device of this example, the upper side of the figure is the viewing side, and when a backlight is provided, it is arranged on the lower side of the figure. In this case, the surface treatment layer 4 can be a hard coat layer, an antireflection layer, an antiglare layer, or the like. The other optical layer 5 can be a reflective layer, a transflective layer, a light collector, a brightness enhancement film, or the like.

  Furthermore, the polarizing plate of the present invention is also effectively used in a circularly polarized or elliptically polarized mode having an antireflection function in an image display device other than a liquid crystal display device, for example, a flat display such as an organic EL display device. Those skilled in the art will easily understand that when the image display element is an organic EL display element, the polarizing plate of the present invention may be bonded to one side thereof, that is, the viewing side display surface. Of course, the image display apparatus to which the polarizing plate of the present invention is applied is not limited to the one exemplified here.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples, the storage elastic modulus of the pressure-sensitive adhesive is a value measured by the following method.

[Measurement method of storage modulus]
An adhesive having a thickness of 25 μm was laminated, and a cylindrical test piece having a thickness of 8 mmφ × 1 mm was produced from the adhesive. With respect to the cylindrical test piece, in accordance with JIS K7244, using a measuring instrument “DYNAMIC ANALYZER RDA II” manufactured by REOMETRIC, a storage elastic modulus (G ′) at 23 ° C. and 80 ° C. by a torsional shear method with a frequency of 1 Hz. Asked.

  In the following examples, the following were used as adhesives.

Adhesive A
An organic solvent solution in which a urethane acrylate oligomer is blended with a copolymer of butyl acrylate and acrylic acid and an isocyanate crosslinking agent is added to a 38 μm-thick polyethylene terephthalate film (separate film) subjected to a release treatment. A sheet-like pressure-sensitive adhesive coated on the release-treated surface so as to have a thickness of 25 μm after drying with a die coater. The storage elastic modulus of this pressure-sensitive adhesive layer was 0.40 MPa at 23 ° C. and 0.18 MPa at 80 ° C.

Adhesive B
A commercially available sheet-like pressure-sensitive adhesive in which an acrylic pressure-sensitive adhesive layer having a thickness of 25 μm is provided on a release-treated surface of a polyethylene terephthalate film (separate film) having a thickness of 38 μm that has been subjected to a release treatment. No urethane acrylate oligomer is blended. The storage elastic modulus of this pressure-sensitive adhesive layer was 0.05 MPa at 23 ° C. and 0.04 MPa at 80 ° C.

Adhesive C
A commercially available sheet-like pressure-sensitive adhesive in which a pressure-sensitive adhesive layer having a thickness of 15 μm is provided on a release-treated surface of a polyethylene terephthalate film (separate film) having a thickness of 38 μm that has been subjected to a release treatment. No urethane acrylate oligomer is blended. The storage elastic modulus of this pressure-sensitive adhesive layer was 0.10 MPa at 23 ° C. and 0.04 MPa at 80 ° C.

[Example 1]
A transparent protective layer made of a 40 μm thick triacetylcellulose film is formed of an aqueous solution containing polyvinyl alcohol and a water-soluble epoxy resin on one side of a polarizer made of a 25 μm thick film in which iodine is adsorbed and oriented on polyvinyl alcohol. A polarizing plate bonded with an adhesive was prepared. Adhesive A was attached to the polyvinyl alcohol polarizer side to obtain a thin polarizing plate corresponding to FIG.

  Separately, adhesive A is applied to one side of a retardation film (“Scina film” manufactured by Sekisui Chemical Co., Ltd .: trade name) made of a norbornene resin having a thickness of 25 μm and an in-plane retardation of 140 nm. A retardation film with an adhesive was prepared. After peeling the separate film of the thin polarizing plate obtained earlier, the optical retardation is the polarization of the polarizing plate on the side where the pressure-sensitive adhesive film is not provided on the pressure-sensitive adhesive layer side. A polarizing plate with a retardation film corresponding to FIG. 2 was produced by bonding so as to form an angle of 45 ° with respect to the absorption axis.

Comparative Example 1
A polarizing plate with a retardation film was produced in the same manner as in Example 1 except that the adhesive A provided on one side of the retardation film was changed to the adhesive B.

Comparative Example 2
A polarizing plate with a retardation film was produced in the same manner as in Example 1 except that the adhesive A provided on one side of the retardation film was changed to the adhesive C.

[Durability evaluation of polarizing plate]
The polarizing plate with retardation film produced in Example 1 and Comparative Examples 1 and 2 is 2.7 inches (about 6.9 cm) in diagonal size so that the polarization absorption axis is 30 degrees with respect to the long side. Cut out. Next, the pressure-sensitive adhesive layer side was attached to a glass plate having a thickness of 0.7 mm, and autoclaved for 20 minutes under the conditions of a temperature of 50 ° C. and a pressure of 0.5 MPa. After natural cooling, each sample was put into an oven maintained at 85 ° C. and subjected to a heating test for 500 hours. About the sample after this heating test, the raised height generated within 2 mm from the end of the polarizing plate was measured using a confocal interference microscope “PL-μ2300” manufactured by SENSOFAR.

  Here, the raised height means the height from the end of the polarizing plate to the top of the raised portion on the basis of the horizontal plane of the main portion exceeding 2 mm inside (the portion where no rising occurs). The evaluation results are shown in Table 1 together with the structure of the pressure-sensitive adhesive. Further, the rising state of the end portion of the polarizing plate is shown in a graph in FIG. In FIG. 4, the horizontal axis represents the distance (μm) from the end of the polarizing plate, and the vertical axis represents the height (μm) from the reference plane. In each example, the maximum value is shown around 100 μm (0.1 mm) from the end of the polarizing plate, and once it becomes lower than the reference plane, it is 1,500 μm (1.5 mm) from the end of the polarizing plate. From the position inside the front and rear, the height is almost constant (reference plane), and it can be seen that the example 1 shows the smallest raised height.

  From the results in Table 1, the polarizing plate of the present invention obtained in Example 1 is the same as Example 1 except that the storage modulus of the adhesive in the outermost layer is different when placed in a high temperature environment of 85 ° C. Compared to the thin polarizing plates of Comparative Examples 1 and 2 employing the above configuration, it was confirmed that the swell generated within 2 mm from the end of the polarizing plate was suppressed. Therefore, the polarizing plate of the present invention can maintain good durability.

Examples 2 to 6 and Comparative Example 3
An adhesive material (a) having the composition shown in Table 2 (in terms of solid content) was prepared, and toluene was added as a solvent to obtain a coating solution having a solid content adjusted to 20% by mass. Using this coating solution, a knife-type coating was applied to the release-treated surface of a 38 μm thick polyethylene terephthalate separate film [“SP-PET 382050” manufactured by Lintec Corporation] to a thickness of 25 μm after drying. After applying with a machine, the adhesive material layer was formed by drying at 90 ° C. for 1 minute.
Next, the adhesive material layer is bonded to one side of a retardation film made of a norbornene-based resin having a thickness of 25 μm and an in-plane retardation of 140 nm (“Essina film” manufactured by Sekisui Chemical Co., Ltd .: trade name). Five minutes after the irradiation, ultraviolet rays (UV) were irradiated from the side of the separate film under the following conditions to produce a retardation film with an adhesive layer. The thickness of the pressure-sensitive adhesive layer was 25 μm.
Furthermore, after preparing the thin polarizing plate of Example 1 separately and peeling the separate film, the optical axis of the polarizing plate of the above-mentioned retardation film with pressure-sensitive adhesive is the polarizing plate. The polarizing plate with a retardation film corresponding to FIG. 2 was obtained by bonding so as to form 45 ° with respect to the polarization absorption axis.
<UV irradiation conditions>
Fusion Co. electrodeless lamp H bulb used, illuminance 600 mW / cm ^2, light quantity 150 mJ / cm ²
“UVPF-36” manufactured by Eye Graphics Co., Ltd. was used as the UV illuminance / light meter.

Examples 7 to 9 and Comparative Example 4
An adhesive material (a) having the composition shown in Table 2 (in terms of solid content) was prepared, and toluene was added as a solvent to obtain a coating solution having a solid content adjusted to 20% by mass. Using this coating solution, a knife-type coating was applied to the release-treated surface of a 38 μm thick polyethylene terephthalate separate film [“SP-PET 382050” manufactured by Lintec Corporation] to a thickness of 25 μm after drying. After applying with a machine, the adhesive material layer was formed by drying at 90 ° C. for 1 minute.
Next, an aqueous solution in which a transparent protective layer made of a triacetyl cellulose film having a thickness of 40 μm is formed on one surface of a polarizer made of a film having a thickness of 25 μm in which iodine is adsorbed and oriented on polyvinyl alcohol. A polarizing plate bonded through an adhesive made of was prepared. 5 minutes after sticking the adhesive material layer to the polyvinyl alcohol polarizer side, ultraviolet rays (UV) were irradiated from the separate film side under the same conditions as described above, and a 25 μm thick adhesive layer corresponding to FIG. A polarizing plate was obtained.

(note)
1) BA / HEA: copolymer of butyl acrylate and 2-hydroxyethyl acrylate, () is charged mass ratio 2) BA / AA: copolymer of butyl acrylate and acrylic acid, () is charged Mass ratio 3) BA / HEA / AA: butyl acrylate, 2-hydroxyethyl acrylate, acrylic acid copolymer, () is charged mass ratio 4) polyfunctional acrylate monomer: tris (acryloxyethyl) isocyan Nurate, molecular weight = 423, trifunctional type (manufactured by Toa Gosei Co., Ltd., trade name “Aronix M-315”)
5) Photopolymerization initiator: mixture of benzophenone and 1-hydroxycyclohexyl phenyl ketone in a mass ratio of 1: 1, “Irgacure 500” manufactured by Ciba Specialty Chemicals
6) Polyisocyanate compound (crosslinking agent, adhesion improver): trimethylolpropane modified tolylene diisocyanate ("Coronate L" manufactured by Nippon Polyurethane)
7) Silane coupling agent: 3-glycidoxypropyltrimethoxysilane (“KBM-403” manufactured by Shin-Etsu Chemical Co., Ltd.)

  Evaluation of the performance of the adhesives of Examples 2 to 9 and Comparative Examples 3 to 4 and the performance of the polarizing plate or the polarizing plate with a retardation film was performed as follows. The evaluation results are shown in Table 3.

(1) Measuring method of storage elastic modulus It measured by the same method as the measuring method performed in the said Example 1.
(2) Durability test of polarizing plate By the same method as the measurement method performed in Example 1 above, the rising height of the polarizing plate or the polarizing plate with a retardation film was measured according to predetermined conditions.
(3) Measurement of adhesive strength From a polarizing plate or a polarizing plate with a retardation film, a 25 mm wide and 100 mm long sample was cut out, and the separate film was peeled off (the thickness of the adhesive layer was 25 μm). After being affixed to “1737” manufactured by Kurihara], it was pressurized with an autoclave manufactured by Kurihara Seisakusho under the conditions of 0.5 MPa, 50 ° C. and 20 minutes. Then, after being left for 7 days in an environment of 23 ° C. and a relative humidity of 50%, in that environment, using a tensile tester (“Tensilon” manufactured by Orientec Co., Ltd.), a peeling speed of 300 mm / min, a peeling angle of 180 ° The adhesive strength was measured under the following conditions.
(4) Evaluation of light leakage performance After adjusting a polarizing plate or a polarizing plate with a retardation film to a size of 233 mm × 309 mm with a cutting device (Super cutter “PN1-600” manufactured by Sugano Seiki Seisakusho), alkali-free glass [ After pasting to “1737” manufactured by Corning Inc.], it was pressurized with an autoclave manufactured by Kurihara Seisakusho under the conditions of 0.5 MPa, 50 ° C., and 20 minutes. In addition, the said bonding was performed so that a polarizing axis might be in a crossed Nicol state on the front and back of an alkali free glass, and a polarizing plate or a polarizing plate with a phase difference film. In this state, it was left at 80 ° C. for 200 hours. Then, it was left to stand in an environment of 23 ° C. and a relative humidity of 50% for 2 hours, and the light leakage was evaluated by the following method under the same environment.
Using MCPD-2000 manufactured by Otsuka Electronics Co., Ltd., the brightness of each region shown in FIG. 6 is measured, and the brightness difference ΔL ^* is expressed by the formula ΔL ^* = [(b + c + d + e) / 4] −a
(Where a, b, c, d, and e are the lightness values at predetermined measurement points (one central portion of each region) in the A region, B region, C region, D region, and E region, respectively. ) To obtain light leakage. A smaller value of ΔL ^* indicates that there is less light leakage. Usually, if it is less than 4.0, it can be used for a liquid crystal display device.

  The polarizing plates produced in Examples 2 to 9 and the polarizing plate with a retardation film had high light leakage performance, and the rising height generated at the end of the polarizing plate under a predetermined condition was as low as 2 μm or less. . On the other hand, the polarizing plate of Comparative Examples 3 and 4 and the polarizing plate with a retardation film whose storage elastic modulus at 23 to 80 ° C. of the pressure-sensitive adhesive layer 6 that is bonded to the image display element is outside the scope of the present invention. The rise was higher than 2 μm and could not be said to be low. Furthermore, the polarizing plate with a retardation film of Comparative Example 3 did not have sufficient light leakage performance. Moreover, it was shown that the adhesive strength of the pressure-sensitive adhesive layer after 7 days under the predetermined conditions in Examples 2 to 9 is also excellent in removability as compared with Comparative Examples 3 and 4.

  The polarizing plate of the present invention has a thin and lightweight configuration and is excellent in durability under a high temperature environment. In particular, the present invention is useful for various image display devices for mobile use in which the module itself is thin and light and the durability is improved.

Claims (14)

A transparent protective layer is formed on one side of a polarizer made of a polyvinyl alcohol-based resin film, and a pressure-sensitive adhesive layer is directly provided on the other side of the polarizer, and the polarizing plate is bonded to the image display element via the pressure-sensitive adhesive layer. a is, the pressure-sensitive adhesive layer, shows the storage modulus 0.15~10MPa at twenty-three to eighty ° C.,
When the pressure-sensitive adhesive layer to be bonded to the image display element is attached to glass and placed in a dry heat environment at 85 ° C. for 500 hours, a bulge occurs within 2 mm from the end of the polarizing plate to the inside. The height of the bulge from the edge of the polarizing plate to the top of the bulge that reaches the reference plane after being lower than the reference plane, with the horizontal surface of the main part that does not rise more than 2 mm inside as the reference plane Is a polarizing plate characterized by being 2 μm or less . A transparent protective layer is formed on one side of a polarizer made of a polyvinyl alcohol-based resin film, and a pressure-sensitive adhesive layer is directly provided on the other side of the polarizer, and a transparent polymer film and an outermost pressure-sensitive adhesive layer are formed in this order. The polarizing plate is bonded to the image display element through the outermost pressure-sensitive adhesive layer, and any of the pressure-sensitive adhesive layers exhibits a storage elastic modulus of 0.15 to 10 MPa at 23 to 80 ° C. And
When the pressure-sensitive adhesive layer to be bonded to the image display element is attached to glass and placed in a dry heat environment at 85 ° C. for 500 hours, a bulge occurs within 2 mm from the end of the polarizing plate to the inside. The height of the bulge from the edge of the polarizing plate to the top of the bulge that reaches the reference plane after being lower than the reference plane, with the horizontal surface of the main part that does not rise more than 2 mm inside as the reference plane Is a polarizing plate characterized by being 2 μm or less .   The polarizing plate according to claim 2, wherein an adhesive layer, a transparent polymer film, and an adhesive layer are formed in this order on the other surface of the polarizer, and the transparent polymer film has an in-plane retardation.   The polarizing plate according to claim 1, wherein the pressure-sensitive adhesive layer bonded to the image display element has a thickness of 3 to 25 μm.   The polarizing plate according to claim 1, wherein an optical layer exhibiting another optical function is laminated on the transparent protective layer. The pressure-sensitive adhesive layer to be bonded to the image display element is (A1) an acrylic polymer having a weight-average molecular weight of 1 million or more, wherein the monomer containing a hydroxyl group is 10% by mass or less, and (B1) a carboxyl group Containing an acrylic polymer having a weight average molecular weight of 1 million or more and (C) an active energy ray-curable compound, wherein the monomer-containing monomer is 10% by mass or less, and the mass of component (A1) and component (B1) The pressure-sensitive adhesive material having a ratio of 100: 1 to 100: 50 is composed of a pressure-sensitive adhesive 1 for a polarizing plate formed by irradiating active energy rays, and has a storage elastic modulus of 0.3 to 10 MPa at 23 to 80 ° C. The polarizing plate according to any one of claims 1 to 5 , wherein: The pressure-sensitive adhesive layer bonded to the image display element contains (A2) an acrylic polymer and (C) an active energy ray-curable compound, and (A2) a hydroxyl group-containing monomer 0 to 5 in the monomer constituting the component. It is composed of a pressure-sensitive adhesive 2 for polarizing plate, which is obtained by irradiating an adhesive material containing 0.05% by mass and less than 1.0% by mass of a carboxyl group-containing monomer with active energy rays, and has a temperature of 23 to 80 ° C. the polarizing plate according to any one of claims 1 to 5, characterized in that indicating the storage modulus 0.3~10MPa in. The polarizing plate according to claim 6 or 7 , wherein (C) the active energy ray-curable compound is a polyfunctional (meth) acrylate monomer having a molecular weight of less than 1,000. The polarizing plate according to claim 8 , wherein the polyfunctional (meth) acrylate monomer has a cyclic structure. The polarizing plate according to claim 8 , wherein the polyfunctional (meth) acrylate monomer has an isocyanurate structure. The polarizing plate according to any one of claims 6 to 10 , wherein the adhesive material further contains (D) a crosslinking agent. The polarizing plate according to claim 11 , wherein (D) the crosslinking agent is a polyisocyanate compound. The polarizing plate according to any one of claims 6 to 12 , wherein the adhesive material further contains (E) a silane coupling agent. Image and the image display device, characterized by a polarizing plate, the outermost is the adhesive layer of the polarizing plate is stuck to the image display device according to any one of claims 1 to 13 Display device.

Images