KR20160076448A - Polarizing plate with protective film and laminate comprising the same - Google Patents

Abstract

The purpose of the present invention is to provide a polarizing plate having a protection film attached thereto and a multilayer body comprising the same. According to the present invention, the polarizing plate includes: a polarization plate comprising a polarizer; and the protection film stacked on one surface thereof. The protection film has a water vapor transmission rate less than or equal to 15 g/(m^2·24 hours) at 40°C and 90% relative humidity.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a polarizing plate having a protective film and a laminate including the polarizing plate,

The present invention relates to a polarizing plate with a protective film formed by laminating a protective film on the surface of a polarizing plate and a laminated body including the polarizing plate.

2. Description of the Related Art In recent years, mobile terminals such as smart phones have been rapidly increasing in size and size in terms of design and portability. In order to realize driving with a limited thickness for a long time, the polarizing plate used is required to have a high brightness and a thin and light weight.

As a polarizing plate, conventionally, a protective film made of triacetylcellulose is bonded to both sides of a polyvinyl alcohol polarizer by a polyvinyl alcohol-based adhesive. However, recently, from the viewpoints of thinning, durability, cost, productivity, and the like, in recent years, various protective resins such as triacetyl cellulose, various resins such as a (meth) acrylic resin, a chain polyolefin resin and a cyclic polyolefin resin, (See, for example, Japanese Patent Application Laid-Open No. 2004-245925, paragraph [0005]).

As described above, in recent years, there is a tendency that a thin and weakly polarizing plate is used. However, such a polarizing plate tends to be susceptible to a change in the environment in which it is placed, in particular, a temperature change and a humidity change, and tends to cause deformation represented by curl (warp) according to environmental changes. The polarizing plate is generally distributed on the market as a polarizing plate with a protective film to which a peelable protective film (also referred to as a surface protective film) for protecting the surface is adhered. However, the above-described tendency is the same in polarizing plates with a protective film.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a polarizing plate with a protective film and a laminate including the same, which does not easily cause curling due to temperature change and humidity change.

The present invention provides the following polarizing plate with an protect film and an image display apparatus.

[1] A polarizing plate comprising a polarizing plate including a polarizer, and a protective film laminated on one surface of the polarizing plate,

Wherein the protective film has a moisture permeability (M) of 15 g / (m 2 · 24 hr) or less at a temperature of 40 ° C. and a relative humidity of 90%.

[2] A polarizing plate with a protective film according to [1], wherein the thickness of the polarizing plate is 125 탆 or less.

[3] The polarizing plate with a protective film according to [1] or [2], wherein the other surface of the polarizing plate is composed of the surface of the first pressure-sensitive adhesive layer.

[4] The polarizing plate with a protective film according to any one of [1] to [3], wherein the protective film comprises a second pressure-sensitive adhesive layer laminated on the one surface and a single-layer base film laminated thereon.

[5] The polarizing plate according to any one of [1] to [4], wherein the polarizing plate further comprises a protective film laminated on at least one surface of the polarizer through a cured layer of an active energy ray curable adhesive.

[6] The other surface of the polarizer is composed of the surface of the first pressure-sensitive adhesive layer,

The polarizing plate with a protective film according to any one of [1] to [5], further comprising a separate film laminated on the other surface of the polarizing plate.

[7] The polarizing plate may further include an optical film other than the polarizer,

The polarizing plate with a protective film according to any one of [1] to [6], wherein the protective film is laminated on the surface of the optical film.

[8] The polarizing plate with a protective film according to [7], wherein the optical film is a brightness enhancement film.

[9] A polarizing plate with a protective film according to any one of [1] to [8], wherein the polarizer has a thickness of 15 μm or less.

[10] A laminate comprising an image display element and a polarizing plate having a protective film according to any one of [1] to [9] laminated thereon.

According to the present invention, it is possible to provide a polarizing plate with a protective film and a laminate including the same, which does not readily cause curling due to temperature change and humidity change. The polarizing plate with a protective film and the laminate including the polarizing plate can be suitably used for an image display apparatus.

1 is a schematic cross-sectional view schematically showing an example of the layer structure of a polarizing plate with a protective film according to the present invention.
2 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate with a protective film according to the present invention.
3 is a schematic cross-sectional view showing another example of the layer structure of the polarizing plate with a protective film according to the present invention.
4 is a schematic cross-sectional view showing still another example of the layer structure of a polarizing plate with a protective film according to the present invention.

≪ Polarizer with Protect Film >

(1) Composition of Polarizer with Protect Film

1 is a schematic cross-sectional view schematically showing an example of the layer structure of a polarizing plate with a protective film according to the present invention. An example of a polarizing plate with a protective film of the present invention will be described with reference to Fig. The polarizing plate with a protective film of the present invention comprises a polarizing plate 100 including a polarizer (not shown in Fig. 1), and a protective film 60 laminated on one surface of the polarizing plate. The surface of the polarizing plate 100 on the side of the protective film 60 (the surface to which the protective film 60 is bonded) may be a surface of a protective film, another optical film, or a layer added on the film.

The other surface of the polarizing plate 100, that is, the surface opposite to the surface on which the protective film 60 is laminated is not particularly limited. As shown in FIG. 1, for example, the surface of the first pressure- . In this case, a peelable separate film 70 for temporarily protecting the surface may be laminated on the outer surface (the other surface of the polarizing plate 100) of the first pressure-sensitive adhesive layer 31.

The protective film 60 is composed of a base film 61 and a second pressure-sensitive adhesive layer 62 laminated on the base film 61. The pressure-sensitive film 60 is laminated to the polarizing plate 100 through the pressure-sensitive adhesive layer.

In the present invention, the polarizing plate 100 is a polarizing element including at least a polarizer, and usually includes a protective film bonded to one side or both sides thereof. In addition to the protective film, it may include another optical film such as a film having a different optical function from the polarizer, or a layer added onto the film such as an optical layer. Various optical films including a protective film can be bonded together through an adhesive layer or a pressure-sensitive adhesive layer. It is assumed that the separator film 70 is not included in the polarizing plate 100 when one outermost layer of the polarizer 100 is the first pressure-sensitive adhesive layer 31 and the separate film 70 is laminated on the outer surface thereof.

The total moisture permeability (M) including the second pressure-sensitive adhesive layer (62) is not more than 15 g / (m 2 · 24 hr) under the conditions of a temperature of 40 ° C. and a relative humidity of 90%. The moisture permeability (M) is preferably 12 g / (m 2 · 24 hr) or less. This makes it possible to effectively suppress the curl according to the temperature change and the humidity change of the polarizing plate with the protective film. The curling is suppressed by 1) the polarizing plate is folded due to stress in the process, 2) foreign matter is mixed between the protective film and the polarizing plate by deformation (distortion) due to curling, and 3) It is advantageous in suppressing the problem of causing a joining mistake when joining to the device or causing the joining of bubbles to the joining interface. The moisture permeability (M) is measured by the cup method defined in JIS Z 0208. The moisture permeability (M) is usually at least 0 g / (m 2 · 24 hr), more typically at least 0 g / (m 2 · 24 hr).

The thickness T of the polarizing plate 100 is usually 200 占 퐉 or less and preferably 150 占 퐉 or less, more preferably 125 占 퐉 or less, further preferably 100 占 퐉 or less, from the viewpoint of thinning. The smaller the thickness T, the more likely to cause curling, but according to the present invention, curling can be effectively suppressed even in this case. The thickness (T) is usually 50 占 퐉 or more.

The polarizing plate with a protective film preferably satisfies the following formula (1): " (1) "

M? T / 15 + 10 (One)

This makes it possible to effectively suppress the curl according to the temperature change and the humidity change depending on the thickness T of the polarizing plate 100. [ In one preferred embodiment, the polarizing plate with a protective film satisfies M? 15 and T? 100 and satisfies the above formula (1).

When the humidity expansion coefficient of the polarizing plate 100 is C ₁ and the humidity expansion coefficient of the protection film 60 is C ₂ , the absolute value of these differences is preferably 50 [ppm ·% RH ^-1 ] or less , And more preferably 30 [ppm ·% RH ^-1 ] or less. This makes it possible to more effectively suppress the curl according to the temperature change and the humidity change of the polarizing plate with a protective film. The absolute value of the difference is 0 or more and may be 10 [ppm ·% RH ^-1 ] or more. The humidity expansion coefficients C ₁ and C ₂ are measured according to the description of the embodiment of the later-described embodiments.

The polarizing plate with a protective film according to the present invention is usually a plate of a polarizing plate with a protective film. In the present invention, the raw material film continuously fed out from the film roll is laminated with another raw film which is continuously unwound from the film roll, and the obtained long laminated film is rolled up , A polarizing plate with a long protective film is produced by the so-called roll-to-roll method, and then the polarizing plate is cut.

The shape of each of the green bodies is not particularly limited, but preferably has a rectangular shape with a long side and a short side, and is typically rectangular. The length of the long side and the short side are not particularly limited, but usually, the long side of each leaf is at least 50 mm and the short side is at least 30 mm. Curl is more likely to occur when the size of each leaf is larger. If the size (long side and / or short side) is too small, the curl problem itself does not easily occur.

Next, examples of the layer structure of the polarizing plate 100 are described with reference to Figs. 2 to 4. However, the layer structure is not limited to these examples. For example, the other surface of the polarizing plate, that is, the surface opposite to the surface on which the protective film 60 is laminated is not limited to the first pressure-sensitive adhesive layer 31 but may be an optical film such as a protective film or a layer Or may be composed of a surface.

2 has a polarizer 10, a protective film 21 bonded to one surface of the polarizer 10, a protective film 22 bonded to the other surface of the polarizer 10, a protective film 22 And a first pressure-sensitive adhesive layer 31 laminated on the outer surface of the first pressure-sensitive adhesive layer. 3 has a polarizer 10, a protective film 21 bonded to one surface of the polarizer 10, a protective film 22 bonded to the other surface of the polarizer 10, a protective film 22 And a brightness enhancement film 50 as an optical film which is laminated on the outer surface of the protective film 21 through a third pressure sensitive adhesive layer 32. The first pressure sensitive adhesive layer 31 is formed on the outer surface of the protective film 21, The polarizing plate of the polarizing plate with a protective film shown in Fig. 4 has a structure in which the protective film 21 is omitted and the third pressure-sensitive adhesive layer 32 is directly laminated on the surface of the polarizer 10, And has the same layer configuration as the polarizing plate.

Although not shown, bonding of the polarizer 10 and the protective films 21 and 22 can be performed using an adhesive.

(2) Polarizer

The polarizer 10 is an absorption type polarizer that absorbs linearly polarized light having a vibration plane parallel to its absorption axis and transmits linearly polarized light having a vibration plane perpendicular to the absorption axis (parallel to the transmission axis) A polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film can be suitably used. The polarizer 10 is, for example, a step of uniaxially stretching a polyvinyl alcohol based resin film; A step of adsorbing a dichroic dye by staining a polyvinyl alcohol-based resin film with a dichroic dye; Treating a polyvinyl alcohol-based resin film adsorbed with a dichroic dye with an aqueous solution of boric acid; And a step of washing with water after treatment with an aqueous boric acid solution.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include a copolymer of vinyl acetate, which is a homopolymer of vinyl acetate, and other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include (meth) acrylamides having unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids and ammonium groups, and the like.

The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000. The average polymerization degree of the polyvinyl alcohol-based resin can be obtained according to JIS K 6726.

This polyvinyl alcohol-based resin film is used as a raw film of the polarizer 10 (polarizing film). The method of forming the polyvinyl alcohol-based resin is not particularly limited, and a known method is employed. Although the thickness of the polyvinyl alcohol type original film is not particularly limited, it is preferable to use a film having a thickness of 5 to 35 탆 in order to make the thickness of the polarizer 10 15 탆 or less. More preferably, it is 20 mu m or less. It is necessary to increase the stretching magnification by obtaining a polarizer 10 having a thickness of 15 m or less by stretching a polyvinyl alcohol type original film having a thickness exceeding 35 m. When the thickness of the polarizer 10 is 15 m or less The dimensional shrinkage under high temperature environment is also increased. When the thickness is less than 5 占 퐉, the handling property at the time of stretching is lowered, and problems such as cutting are liable to occur at the time of producing the polarizer.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. When uniaxial stretching is carried out after dyeing, this uniaxial stretching may be carried out before the boric acid treatment or during the boric acid treatment. In addition, the uniaxial stretching may be performed in a plurality of these steps.

In the uniaxial stretching, the film may be uniaxially stretched between rolls having different peripheral velocities, or may be uniaxially stretched using a thermal roll. The uniaxial stretching may be dry stretching in which stretching is performed in the atmosphere, or wet stretching in which stretching is performed in a state in which a polyvinyl alcohol based resin film is swollen with a solvent or water. The draw ratio is usually 3 to 8 times.

As a method for dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing the film in an aqueous solution containing a dichroic dye can be employed. As the dichroic dye, iodine or a dichroic organic dye is used. It is preferable that the polyvinyl alcohol based resin film is subjected to immersion treatment in water before the dyeing treatment.

As a dyeing treatment with iodine, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is generally employed. The content of iodine in this aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution is usually 20 to 40 占 폚. On the other hand, as a dyeing treatment with a dichroic organic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic organic dye is usually employed. The aqueous solution containing the dichroic organic dye may contain an inorganic salt such as sodium sulfate as a dyeing aid. The content of the dichroic organic dye in this aqueous solution is usually 1 x ^10-4 to 10 parts by weight per 100 parts by weight of water. The temperature of this aqueous solution is usually from 20 to 80 캜.

The boric acid treatment after dyeing with a dichroic dye generally employs a method of immersing a dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid. When iodine is used as the dichroic dye, it is preferable that the aqueous solution containing boric acid contains potassium iodide. The amount of boric acid in the boric acid-containing aqueous solution is usually 2 to 15 parts by weight per 100 parts by weight of water. The amount of potassium iodide in this aqueous solution is usually 0.1 to 15 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution may be 50 占 폚 or higher, for example, 50 to 85 占 폚.

The polyvinyl alcohol resin film after boric acid treatment is usually subjected to water washing treatment. The water washing treatment can be carried out, for example, by immersing the boric acid-treated polyvinyl alcohol resin film in water. The temperature of the water in the water washing treatment is usually 5 to 40 캜.

After washing with water, drying treatment is performed to obtain the polarizer 10. The drying treatment can be performed using a hot-air dryer or a far-infrared heater. The thickness of the polarizer 10 is preferably 15 占 퐉 or less, more preferably 10 占 퐉 or less. Setting the thickness of the polarizer 10 to 15 m or less is advantageous for reducing the thickness of the polarizing plate 100 and further the image display apparatus. The thickness of the polarizer 10 is usually 2 占 퐉 or more. According to the present invention, even when the thickness of the polarizer 10 is as thin as 15 占 퐉 or less, curling due to temperature change and humidity change of the polarizing plate with a protective film can be suppressed.

By the drying treatment, the water content of the polarizer 10 is reduced to a practically acceptable level. The water content thereof is usually 5 to 20% by weight, preferably 8 to 15% by weight. If the moisture content is less than 5% by weight, flexibility of the polarizer 10 is lost, and the polarizer 10 may be damaged or broken after drying. If the moisture content exceeds 20% by weight, the thermal stability of the polarizer 10 may be poor.

(3) Protective film

The protective films 21 and 22 which can be laminated on one surface or both surfaces of the polarizer 10 are made of a thermoplastic resin having transparency (preferably optically transparent) such as a chain polyolefin resin (polypropylene type resin) Polyolefin resins such as cyclic polyolefin resins (norbornene resins and the like); Cellulose-based resins such as triacetylcellulose and diacetylcellulose; Polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate resin; (Meth) acrylic resins such as methyl methacrylate resins; Polystyrene type resin; Polyvinyl chloride resins; Acrylonitrile-butadiene-styrene-based resin; Acrylonitrile-styrene series resin; Polyvinyl acetate resin; Polyvinylidene chloride resins; Polyamide based resin; A polyacetal-based resin; Modified polyphenylene ether-based resin; Polysulfone resins; Polyether sulfone type resin; Polyarylate resins; Polyamideimide series resin; A polyimide-based resin, or the like. Among them, it is preferable to use a polyolefin resin or a cellulose resin. In the present specification, the term "(meth) acrylic resin" refers to at least one kind selected from the group consisting of an acrylic resin and a methacrylic resin. The same applies to the term to which the other " (meth) " is appended.

Examples of the chain polyolefin-based resin include a homopolymer of a chain olefin such as a polyethylene resin and a polypropylene resin, and a copolymer composed of two or more chain olefins.

The cyclic polyolefin-based resin is a generic name of a resin that is polymerized using a cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin-based resin include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers (typically, random copolymers) of cyclic olefins and chain olefins such as ethylene and propylene, Graft polymers modified with carboxylic acids or their derivatives, and hydrides thereof. Among them, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is preferably used.

The cellulose-based resin is a resin in which part or all of the hydrogen atoms in the hydroxyl group of the cellulose obtained from the raw cellulose such as cotton linters and wood pulp (hardwood pulp, softwood pulp) and the like are substituted with an acetyl group, a propionyl group and / or a butyryl group , A cellulose organic acid ester, or a cellulose mixed organic acid ester. Examples thereof include acetate esters of cellulose, propionic acid esters, butyric acid esters, and mixed esters thereof. Among them, triacetylcellulose, diacetylcellulose, cellulose acetate propionate and cellulose acetate butyrate are preferable.

The (meth) acrylic resin is a polymer containing a constituent unit derived from a (meth) acrylic monomer. The polymer is typically a polymer comprising a methacrylate ester. Preferably, the ratio of the structural units derived from methacrylic acid ester is 50% by weight or more based on the total structural units. The (meth) acrylic resin may be a homopolymer of methacrylic acid ester, or may be a copolymer containing constituent units derived from other polymerizable monomers. In this case, the proportion of the structural units derived from the other polymerizable monomer is preferably 50% or less with respect to the total structural units.

As the methacrylic acid ester which can constitute the (meth) acrylic resin, an alkyl methacrylate ester is preferable. Examples of the methacrylic acid alkyl ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, , 2-ethylhexyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, and the like. The number of carbon atoms of the alkyl group contained in the methacrylic acid alkyl ester is preferably 1 to 4. In the (meth) acrylic resin, the methacrylic acid ester may be used alone, or two or more kinds thereof may be used in combination.

Examples of the other polymerizable monomer capable of constituting the (meth) acrylic resin include an acrylic acid ester and other compounds having a polymerizable carbon-carbon double bond in the molecule. As the other polymerizable monomers, only one type may be used alone, or two or more types may be used in combination. As the acrylic acid ester, acrylic acid alkyl ester is preferable. Examples of the alkyl acrylate include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, And alkyl acrylates having 1 to 8 carbon atoms in the alkyl group such as ethyl. The number of carbon atoms of the alkyl group contained in the alkyl acrylate is preferably 1 to 4. In the (meth) acrylic resin, the acrylic acid ester may be used alone or in combination of two or more.

Other compounds having a polymerizable carbon-carbon double bond in the molecule include vinyl compounds such as ethylene, propylene and styrene, and vinyl cyan compounds such as acrylonitrile. The other compounds having a polymerizable carbon-carbon double bond in the molecule may be used alone, or two or more of them may be used in combination.

It is also useful to control the retardation values of the protective films 21 and 22 to values suitable for an image display device such as a liquid crystal display device. For example, in an in-plane switching (IPS) mode liquid crystal display device, it is preferable to use a film having substantially zero retardation value as the protective film 22. Substantially zero phase retardation value means that the in-plane retardation value R ₀ at a wavelength of 590 nm is 10 nm or less, the absolute value of the thickness direction retardation value R _{th at} a wavelength of 590 nm is 10 nm or less, and the wavelengths 480 to 750 Nm means that the absolute value of the thickness direction retardation value R _th is 15 nm or less.

Depending on the mode of the liquid crystal display device, the protective films 21 and 22 may be subjected to stretching and / or shrinking to give appropriate retardation values. For example, a single-layer or multi-layered retardation layer (or film) may be used as the protective film 22 for the purpose of viewing angle compensation. In this case, the polarizing plate 100 may be an elliptically polarizing plate or a circularly polarizing plate including a lamination structure of the polarizer 10 and a retardation layer, or a polarizing plate having a viewing angle compensating function including a retardation layer.

The thickness of the protective films 21 and 22 is usually 1 to 100 占 퐉, but is preferably 5 to 60 占 퐉, more preferably 5 to 50 占 퐉, from the viewpoints of strength and handleability. If the thickness is within this range, the polarizer 10 is mechanically protected and the polarizer 10 does not shrink even when exposed under a humid environment, and stable optical characteristics can be maintained. As the protective films 21 and 22 are thinned, curling due to a temperature change and a humidity change easily occurs. However, according to the present invention, even if the thickness of the protective films 21 and 22 is as thin as 30 m or less, It is possible to suppress the curl.

The polarizing plate 100 may have a structure that does not have at least one of the protective films 21 and 22 from the viewpoint of thinning of the polarizing plate 100. The polarizing plate 100 preferably has a protective film on at least one surface of the polarizing plate 10. [ When a protective film is laminated only on one side of the polarizer 10, curling is likely to occur due to a temperature change and a humidity change. However, according to the present invention, curling due to temperature change and humidity change can also be suppressed.

In the case where a protective film is laminated on only one side of the polarizer 10, on the side opposite to the side where the protective film is laminated in the polarizer 10, an active energy ray-curable resin composition The protective layer may be formed. By forming the protective layer, even if the protective film is provided on only one side of the polarizer 10, it is possible to more effectively suppress the curl and the deterioration of the polarizer 10 due to the temperature change and the humidity change.

In the case where a protective film is bonded to both surfaces of the polarizer 10, these protective films may be composed of the same type of thermoplastic resin or may be composed of different kinds of thermoplastic resins. The thickness may be the same or different. Further, they may have the same retardation characteristics or different retardation characteristics.

At least one of the protective films 21 and 22 is provided with a hard coat layer, an antiglare layer, a light diffusion layer, a retardation layer (a retardation layer having a retardation value of 1/4 wavelength, Or the like), a surface treatment layer (coating layer) such as an antireflection layer, an antistatic layer, and an antifouling layer or an optical layer.

If the constitution of the protective film laminated on both surfaces of the polarizer 10 (the presence or absence of the resin species, the thickness and the surface treatment layer) is different from each other, the curl is likely to occur due to the temperature change and the humidity change. It is possible to suppress the curl according to the temperature change and the humidity change.

The protective films 21 and 22 can be bonded to the polarizer 10 through, for example, an adhesive layer. As the adhesive for forming the adhesive layer, an aqueous adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and preferably an aqueous adhesive and an active energy ray-curable adhesive.

Examples of the water-based adhesive include an adhesive made of a polyvinyl alcohol-based resin aqueous solution, an aqueous two-component emulsion type urethane emulsion adhesive, and the like. Among them, an aqueous adhesive composed of a polyvinyl alcohol-based resin aqueous solution is suitably used. Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol-based resins obtained by saponifying a copolymer of vinyl acetate and other monomers copolymerizable therewith, as well as a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate Or a modified polyvinyl alcohol-based polymer obtained by partially modifying a hydroxyl group thereof, and the like can be used. The water-based adhesive may include a crosslinking agent such as an aldehyde compound (glyoxal, etc.), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound or a polyvalent metal salt.

When an aqueous adhesive is used, it is preferable to carry out a drying step for removing water contained in the water-based adhesive after bonding the polarizer 10 and the protective films 21 and 22 to each other. After the drying step, a curing step for curing at a temperature of 20 to 45 占 폚 may be provided.

The active energy ray-curable adhesive refers to an adhesive that is cured by irradiating active energy rays such as ultraviolet rays or electron beams. For example, a curable composition containing a polymerizable compound and a photopolymerization initiator, a curable composition containing a photoreactive resin, And a curable composition containing a photoreactive crosslinking agent. Preferably an ultraviolet curable adhesive. Examples of the polymerizable compound include photopolymerizable monomers such as a photocurable epoxy monomer, a photocurable (meth) acrylic monomer, a photocurable urethane monomer, and an oligomer derived from a photopolymerizable monomer. Examples of the photopolymerization initiator include those that generate active species such as neutral radicals, anion radicals, and cation radicals upon irradiation with active energy rays. An active energy ray-curable adhesive comprising a polymerizable compound and a photopolymerization initiator, which comprises a curable composition comprising a photo-curable epoxy monomer and a photo cationic polymerization initiator, a curable composition comprising a photo-curable (meth) acrylic monomer and a photo radical polymerization initiator , Or a mixture of these curable compositions can be preferably used.

As the photo-curable epoxy-based monomer, an alicyclic epoxy compound is preferable. The alicyclic epoxy compound refers to a compound having at least one structure in which the oxirane ring is formed together with the carbon atoms of the alicyclic ring. The alicyclic epoxy compound may be used singly or in combination of two or more. Refers to a group in which one or more hydrogen atoms have been removed from (CH ₂ ) _m in the structure shown below, in which the oxirane ring is formed together with the carbon atoms of the alicyclic ring. In the following formula, m is an integer of 2 to 5.

Therefore, a compound in which one or more hydrogen atoms of the group (CH ₂ ) _m are removed from other chemical structures may be an alicyclic epoxy resin. (CH ₂ ) _m may be appropriately substituted with a straight chain alkyl group such as a methyl group or an ethyl group. Among alicyclic epoxy compounds, alicyclic epoxy compounds having an oxabicyclohexane ring (m = 4 in the above formula) and oxabicycloheptane ring (m = 5 in the above formula) It is preferable from the viewpoint of the property. Hereinafter, the alicyclic epoxy compound which is preferably used is specifically exemplified.

In the case of using an active energy ray-curable adhesive, after the polarizer 10 and the protective films 21 and 22 are bonded to each other, a drying step is carried out if necessary, and then the active energy ray curable adhesive is cured Thereby performing a curing process. Therefore, when an active energy ray-curable adhesive is used, the adhesive layer is the cured layer. Although a light source of an active energy ray is not particularly limited, ultraviolet rays having a light emission distribution with a wavelength of 400 nm or less are preferable. Specifically, low energy mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra high pressure mercury lamps, chemical lamps, A mercury lamp, a metal halide lamp, or the like can be used.

In joining the polarizer 10 and the protective films 21 and 22, saponification treatment, corona treatment, plasma treatment, or the like can be performed on at least one of these bonding surfaces in order to improve the adhesiveness.

In the case where the protective film is bonded to both surfaces of the polarizer 10, the adhesive for bonding these protective films may be the same kind of adhesive or different kind of adhesive. In the case of using different kinds of adhesives, curling easily occurs due to a temperature change and a humidity change. However, according to the present invention, curling due to temperature change and humidity change can also be suppressed.

(4) Other optical films

The polarizing plate 100 may include optical films other than the polarizer 10 and the protective films 21 and 22. Typical examples thereof are the brightness enhancement film 50 and the retardation film. When the polarizing plate 100 includes another optical film, the protective film 60 may be laminated on the surface of the optical film.

The brightness enhancement film 50 is also called a reflection type polarizing film, and a polarization conversion element having a function of separating outgoing light from a light source (backlight) into transmitted polarized light and reflected polarized light or scattered polarized light is used. By arranging the brightness enhancement film 50 on the polarizer 10, it is possible to improve the output efficiency of the linearly polarized light emitted from the polarizer 10 by using the recursive light that is the reflected polarized light or the scattered polarized light. The brightness enhancement film 50 can be laminated on the polarizer 10 through the pressure-sensitive adhesive layer (the third pressure-sensitive adhesive layer 32). Another film such as a protective film may be interposed between the polarizer 10 and the brightness enhancement film 50.

The brightness enhancement film 50 may be, for example, an anisotropic reflective polarizer. An example of the anisotropic reflective polarizer is an anisotropic multilayer film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction, and a specific example thereof is " DBEF " 4-268505, etc.). Another example of the anisotropic reflective polarizer is a composite of a cholesteric liquid crystal layer and a? / 4 plate, and a specific example thereof is "PCF" manufactured by Nitto Denko (refer to Japanese Patent Application Laid-open No. 11-231130). Another example of the anisotropic reflective polarizer is a reflective grid polarizer, and specific examples thereof include a metal lattice reflective polarizer (see, for example, U.S. Patent No. 6288840) for performing fine processing on a metal to emit a reflected polarized light even in a visible light region, (See Japanese Unexamined Patent Application, First Publication No. Hei 8-184701 and the like) in a polymer matrix.

The surface activation treatment may be performed in advance on the bonding surface of the brightness enhancement film 50 and the third pressure sensitive adhesive layer 32. [ As a result, under the humidified environment, the peeling between the third pressure-sensitive adhesive layer 32 and the brightness enhancement film 50 is not easily caused, and the polarizing plate 100 having excellent heat and heat durability can be obtained. Examples of the surface activation treatment include dry treatment such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionizing radiation treatment (ultraviolet ray treatment, electron beam treatment and the like); Wet treatment such as ultrasonic treatment using a solvent such as water or acetone, alkali treatment, and anchor coat treatment. These treatments may be performed singly or two or more may be combined. Among them, the corona treatment and the plasma treatment are preferable in order to continuously treat the roll-shaped film.

A surface treatment layer such as a hard coat layer, an antiglare layer, a light diffusion layer, a retardation layer (retardation layer having a retardation value of 1/4 wavelength, etc.), an antireflection layer, an antistatic layer, (Coating layer) or an optical layer may be formed. By forming such a layer, the adhesion to the backlight tape and the uniformity of the display image can be improved. The thickness of the brightness enhancement film 50 is usually 10 to 100 占 퐉, but is preferably 10 to 50 占 퐉, more preferably 10 to 30 占 퐉, from the viewpoint of thinning of the polarizing plate 100. [

(5) Pressure-sensitive adhesive layer (pressure-sensitive adhesive layer)

The first pressure sensitive adhesive layer 31 can be used for bonding a polarizing plate with a protective film to an image display element (e.g., a liquid crystal cell) or another optical member. The third pressure sensitive adhesive layer 32 is used to bond the optical films constituting the polarizing plate 100 (for example, the polarizing film 10 or the protective film 21 with another optical film such as the brightness enhancement film 50) . The first pressure sensitive adhesive layer 31 and the third pressure sensitive adhesive layer 32 may be composed of a pressure sensitive adhesive composition containing a resin such as a (meth) acrylic, rubber, urethane, ester, silicone or polyvinyl ether as a main component. Among them, a pressure-sensitive adhesive composition comprising a (meth) acrylic resin having excellent transparency, weather resistance and heat resistance as a base polymer is suitable. The pressure-sensitive adhesive composition may be an active energy ray-curable type or a thermosetting type.

Examples of the (meth) acrylic resin (base polymer) used in the pressure-sensitive adhesive composition include (meth) acrylates such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, Acrylic acid esters are preferably used as the polymer or copolymer. The base polymer is preferably copolymerized with a polar monomer. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, N, N-dimethylaminoethyl (Meth) acrylate, a hydroxyl group, an amide group, an amino group, an epoxy group and the like.

The pressure-sensitive adhesive composition may contain only the base polymer, but usually contains a crosslinking agent. Examples of the crosslinking agent include a metal ion having a valence of two or more, which forms a carboxylic acid metal salt with a carboxyl group; As the polyamine compound, forming an amide bond with a carboxyl group; As the polyepoxy compound or the polyol, an ester bond is formed with the carboxyl group; As the polyisocyanate compound, an amide bond is formed between the polyisocyanate compound and the carboxyl group. Among them, a polyisocyanate compound is preferable.

The active energy ray-curable pressure-sensitive adhesive composition has a property of curing upon irradiation with an active energy ray such as ultraviolet rays or electron rays and has adhesiveness even before irradiation with active energy rays and can be adhered to an adherend such as a film, And is capable of adjusting the adhesive force. The active energy ray-curable pressure-sensitive adhesive composition is preferably of ultraviolet curing type. The active energy ray-curable pressure-sensitive adhesive composition further contains an active energy ray polymerizable compound in addition to the base polymer and the crosslinking agent. If necessary, a photopolymerization initiator, a photosensitizer or the like may be further contained.

The pressure-sensitive adhesive composition is preferably a pressure-sensitive adhesive composition comprising fine particles, beads (resin beads, glass beads, etc.) for imparting light scattering properties, glass fibers, resins other than the base polymer, tackifiers, fillers (metal powders and other inorganic powders, Ultraviolet absorbers, dyes, pigments, coloring agents, antifoaming agents, corrosion inhibitors, photopolymerization initiators, and the like.

The first pressure sensitive adhesive layer (31) and the third pressure sensitive adhesive layer (32) can be formed by applying an organic solvent diluted solution of the pressure sensitive adhesive composition onto a substrate and drying. The substrate may be a polarizer 10, protective films 21 and 22, another optical film such as a brightness enhancement film 50, a separate film (e.g., separate film 70), or the like. When an active energy ray-curable pressure-sensitive adhesive composition is used, a cured product having a desired degree of curing can be obtained by irradiating an active energy ray to the pressure-sensitive adhesive layer formed.

The thickness of the first pressure sensitive adhesive layer 31 and the thickness of the third pressure sensitive adhesive layer 32 is usually 1 to 40 占 퐉. However, from the viewpoint of thinning of the polarizing plate 100 and suppressing the dimensional change of the polarizing plate 100 while maintaining good processability (For example, 3 to 20 mu m, further 3 to 15 mu m).

The third pressure sensitive adhesive layer 32 preferably exhibits a storage modulus of 0.15 to 1 MPa in a temperature range of 23 to 80 캜. This makes it possible to suppress the dimensional change easily caused by the shrinkage of the polarizer 10 under a humid environment and to enhance the durability of the polarizing plate 100. [ In addition, even when the image display apparatus on which the polarizing plate 100 is mounted is placed under a humid environment, the movement of the polarizing plate 100 is suppressed, so that the reliability of the image display apparatus can be enhanced.

Means that the storage elastic modulus of 0.15 to 1 MPa in the temperature range of 23 to 80 캜 means that the storage elastic modulus is within the above range at any temperature within this range. Since the storage elastic modulus gradually decreases with an increase in temperature, when the storage elastic modulus at 23 deg. C and 80 deg. C falls within the above range, the storage elastic modulus within the above range can be regarded as the storage elastic modulus within the above range. The storage elastic modulus of the third pressure-sensitive adhesive layer 32 can be measured using a commercially available viscoelasticity measuring device, for example, a viscoelasticity measuring device "DYNAMIC ANALYZER RDA II" manufactured by REOMETRIC.

As a method for adjusting the storage elastic modulus to the above range, an oligomer, specifically, an urethane (meth) acrylate oligomer is further added to a pressure-sensitive adhesive composition further comprising a base polymer or a crosslinking agent to form an active energy ray- And a composition (preferably an ultraviolet curable pressure-sensitive adhesive composition). More preferably, the active energy ray is irradiated to properly cure the pressure-sensitive adhesive layer.

The storage elastic modulus of the first pressure sensitive adhesive layer (31) may be the same as or different from that of the third pressure sensitive adhesive layer (32).

(6) Separate film

The separate film 70 is a film temporarily adhered to protect the surface of the first pressure sensitive adhesive layer 31 until the first pressure sensitive adhesive layer 31 is bonded to an image display element (e.g., liquid crystal cell) or another optical member. The separate film 70 is usually made of a thermoplastic resin film subjected to releasing treatment on one side, and the release-treated surface thereof is bonded to the first pressure-sensitive adhesive layer 31. The thermoplastic resin constituting the separate film 70 can be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate. The surface of the third pressure sensitive adhesive layer 32 may be bonded to the surface of the third pressure sensitive adhesive layer 32 in order to protect the surface of the third pressure sensitive adhesive layer 32 until the optical film such as the brightness enhancement film 50 is bonded. The thickness of the separate film 70 is, for example, 10 to 50 占 퐉.

(7) Protective film

The protective film 60 is composed of a base film 61 and a second pressure-sensitive adhesive layer 62 laminated thereon. The protective film 60 is a film for protecting the surface of the polarizing plate 100 and is usually peeled off for each second adhesive layer 62 after the polarizing plate with a protective film is bonded to an image display element or another optical member, Removed.

As described above, the total thickness of the protective film 60 including the second pressure-sensitive adhesive layer 62 is 15 g / (m 2 · 24 hr) or less under the condition of a temperature of 40 ° C. and a relative humidity of 90% Is not more than 12 g / (m 2 · 24 hr). As a method of adjusting the moisture permeability of the protective film 60 within the above range, a material having low moisture permeability may be used as the constituent material of the base film 61. Examples of the low-moisture-permeable material include a low moisture-permeable resin, preferably a thermoplastic resin, specifically, a polyolefin-based resin such as a polyethylene-based resin or a polypropylene-based resin; A cyclic polyolefin-based resin; Polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate; Polycarbonate resin; (Meth) acrylic resins, and the like.

The base film 61 may have a single-layer structure or a multi-layer structure. For example, even when a resin film having a relatively high moisture permeability is used, the moisture permeability of the protection film 60 can be adjusted within the above range by laminating a low moisture permeable film or layer thereon. The base film 61 is preferably a single-layer structure from the viewpoints of ease of manufacture and manufacturing cost.

The moisture permeability of the protective film 60 may be adjusted within the above range by increasing the thickness of the base film 61. The thickness of the base film 61 may be 20 to 190 占 퐉 (e.g., 30 to 140 占 퐉), and the thickness of the protect film 60 may be 60 to 200 占 퐉 (e.g., 70 to 150 占 퐉). The thickness of the protective film 60 exceeding 200 m is disadvantageous in terms of cost, roll transportability and reworkability of the protective film 60. [

Although the description of the first pressure sensitive adhesive layer 31 and the third pressure sensitive adhesive layer 32 is basically referred to for the structure of the second pressure sensitive adhesive layer 62, Or the hygroscopic material (hygroscopic particle or the like) is contained in the second pressure sensitive adhesive layer 62, the moisture permeability of the protective film 60 may be adjusted within the above range. The moisture permeability of the protection film 60 may be adjusted within the above range by combining a plurality of the above-described methods.

The present invention includes the case where the polarizing plate 100 included in the polarizing plate with a protective film has an asymmetrical layer structure with respect to the polarizing element 10 and the like and includes a configuration in which curling is easily caused by temperature change and humidity change . An example of a configuration that tends to cause curling due to temperature change and humidity change is as follows.

(a) The polarizer 10 and / or the protective films 21 and 22 have a thin configuration,

(b) a constitution in which the adhesive layer interposed between the polarizer 10 and the protective film is a cured layer of an active energy ray-curable adhesive,

(c) a configuration in which a protective film is bonded only to one surface of the polarizer 10,

(d) a configuration in which a protective film is bonded to one surface of the polarizer 10 and an optical film (brightness enhancement film or the like) other than a protective film is bonded to the other surface,

(e) a constitution in which the constitution (the resin species, the thickness, the presence or absence of the surface treatment layer, etc.) of the protective film bonded to both surfaces of the polarizer 10 are different from each other,

(f) a structure in which adhesive layers for bonding the protective film to both surfaces of the polarizer 10 are formed of different kinds of adhesives,

(g) a configuration in which a protective film is bonded to both surfaces of the polarizer 10, and another optical film is bonded on one protective film,

(h) In addition, the total number of films and layers on one side is different from the total number of films and layers on the other side, with reference to the polarizer 10.

<Laminate, liquid crystal panel and image display device>

The polarizing plate with a protective film according to the present invention can be suitably applied to a laminate including an image display element and a polarizing plate with a protective film laminated thereon. In this laminate, the polarizing plate with a protective film is bonded to the image display element through the pressure-sensitive adhesive layer (for example, the first pressure-sensitive adhesive layer 31) (after peeling off the separable film such as the separate film 70) . After the polarizing plate with a protective film is bonded to the image display device, the protective film 60 is peeled off at a desired timing. The laminate may be an image display element and a liquid crystal panel or a manufacturing intermediate thereof including a polarizing plate laminated on one side or both sides thereof. The protective film 60 can be obtained by forming a laminated body and then forming a liquid crystal panel in a state in which the protective film 60 is bonded or by using a liquid crystal panel in a state in which the protective film 60 is bonded And is peeled and removed after constructing the image display device. Normally, in the final product as an image display device, the protection film 60 is peeled off.

The image display device may be a liquid crystal display device, an organic EL display device, or the like, but is preferably a liquid crystal display device. A liquid crystal display device includes a liquid crystal panel having a liquid crystal cell as an image display element, and a backlight. In constructing the liquid crystal display device, the polarizing plate with a protective film according to the present invention may be used for a polarizing plate disposed on the viewer side or for a polarizing plate disposed on the backlight side and for polarizing plates on both the viewer side and the backlight side Preferably, however, the polarizing plate with a protective film according to the present invention is used at least for a polarizing plate on the backlight side.

Example

Hereinafter, the present invention is described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples, the moisture permeability, the humidity expansion coefficient, the thickness, the in-plane retardation value R ₀ and the thickness direction retardation value R _th of the film, the storage elastic modulus of the pressure-sensitive adhesive layer, and the curl amount of the polarizing plate with a protective film were measured by the following method .

(1) Water vapor permeability

The moisture permeability [g / (m 2 · 24 hr)] of the protective film at a temperature of 40 ° C. and a relative humidity of 90% was measured by a cup method defined in JIS Z 0208.

(2) Moisture expansion coefficient

The humidity expansion coefficient [ppm ·% RH ^-1 ] of the polarizing plate and the protective film was measured by the following method. The film sample cut into a 100 ㎜ × 100 ㎜ and, 23 ℃ 50% RH during and 23 ℃ 90% humidity expansion coefficient [ppm ·% in accordance with measuring the length of the film transport direction, and expression of the RH during RH ^{- 1} ] Were measured. Here, L50 is the length (mm) in the film transport direction at 23 DEG C and 50% RH, L90 is the length (mm) in the film transport direction at 23 DEG C and 90% RH, )% RH.

Humidity expansion coefficient = (L90-L50) / (L50 x H)

(3) Thickness

Was measured using a digital micrometer &quot; MH-15M &quot; manufactured by Nikon Corporation.

(4) The in-plane retardation value R _e and the thickness direction retardation value R _th

(KOBRA-ADH) manufactured by Oji Paper Co., Ltd., which is a phase difference system based on a parallel Nicol rotation method, was used to measure light with a wavelength of 590 nm, 483 nm, or 755 nm at 23 ° C.

(5) Storage modulus

The storage elastic modulus G 'of the pressure-sensitive adhesive layer was measured according to the following (I) to (III).

Two samples of (25 ± 1 mg) samples are taken from the pressure-sensitive adhesive layer (I) and molded into substantially spherical shapes.

(II) The obtained substantially spherical sample is bonded to the upper and lower surfaces of the I-shaped jig, and the upper and lower surfaces are sandwiched between the L-shaped jig. The measurement sample is composed of an L-shaped jig / adhesive / I-type jig / adhesive / L-shaped jig.

(III) Using the dynamic viscoelasticity measuring device &quot; DVA-220 &quot;, a storage elastic modulus G 'of the thus prepared sample was measured at 23 DEG C or 80 DEG C, Distortion is measured under 1N conditions.

(6) Curl amount

Each sheet having a size of 221 mm x 139 mm was cut out from the polarizing plate with a protective film and the separate film adhered to the first pressure sensitive adhesive layer of this sheet was peeled off and bonded to a 225 mm x 145 mm non- To obtain a measurement sample. The measurement sample was allowed to stand in an environment of 80 DEG C and 90% RH for 5 hours, and returned to room temperature (23 DEG C and 50% RH). Thereafter, the measurement sample was placed on a measuring stand of a 2-dimensional measuring machine &quot; NEXIV VMR-12072 &quot; manufactured by Nikon Corporation with its polarizing plate side up. Subsequently, the surface of the central part of the polarizing plate was focused, and the distance from the reference focus to the four corners of the polarizing plate was measured based thereon. The average distance of the four corners was taken as curl.

(Production of Polarizer)

A polyvinyl alcohol film having a thickness of 20 占 퐉 (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) was vertically uniaxially stretched by about 5 times by dry stretching and immersed in pure water at 60 占 폚 for one minute And then immersed for 60 seconds in an aqueous solution at 28 DEG C in which the weight ratio of iodine / potassium iodide / water was 0.05 / 5/100. Thereafter, the substrate was immersed in an aqueous solution of 72 ° C having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 for 300 seconds. Subsequently, the film was washed with pure water at 26 DEG C for 20 seconds, and then dried at 65 DEG C to obtain a polarizer having a thickness of 7 mu m in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

(Preparation of Protect Film)

The following three types of protective films were prepared.

Protective film A: a base film having a thickness of 75 占 퐉 made of polyethylene terephthalate, a thickness of 13 占 퐉 and a second pressure-sensitive adhesive layer of acrylic type (moisture permeability: 8 g / (m2 占 24 hr) RH ^-1 , total thickness 88 탆)

Protective film B: A base film having a thickness of 75 占 퐉 made of polyethylene terephthalate, a second pressure-sensitive adhesive layer having a thickness of 18 占 퐉 and an acrylic base (moisture permeability of 10 g / (m2 占 24 hr), a humidity expansion coefficient of 6.8 ppm 占% RH ^-1 , total thickness 93 탆)

Protect film C: a base film having a thickness of 38 占 퐉 made of polyethylene terephthalate and a second pressure-sensitive adhesive layer having a thickness of 20 占 퐉 and having an acrylic base (moisture permeability: 17 g / (m2 占 24 hr) RH ^-1 , total thickness: 58 탆)

(Preparation of first protective film)

A film in which an acrylic hard coat layer having a thickness of 7 占 퐉 was laminated on a triacetyl cellulose film (thickness 25 占 퐉, trade name "KC2UA") manufactured by Konica Minolta Co., Ltd. was prepared.

(Preparation of second protective film)

(Thickness: 13 占 퐉, in-plane retardation value at a wavelength of 590 nm, R _e = 0.8 nm, thickness direction retardation value at a wavelength of 590 nm, R _th = 3.4 nm, wavelength: 483 nm) manufactured by Nippon Zeon Co., Thickness retardation value R _th = 3.5 nm and thickness direction retardation value R _th = 2.8 nm at a wavelength of 755 nm) was prepared.

(Preparation of first pressure-sensitive adhesive layer)

A commercially available pressure-sensitive adhesive layer with a 20 占 퐉 thick acrylic pressure-sensitive adhesive layer having a thickness of 38 占 퐉 and made of polyethylene terephthalate having a thickness of 38 占 퐉 and having a thickness of 20 占 퐉 was formed on the releasably treated surface of the separator film as a first pressure- Prepared. The storage elastic modulus of this pressure-sensitive adhesive layer was 0.05 MPa at 23 캜 and 0.04 MPa at 80 캜.

(Preparation of aqueous adhesive)

3 parts by weight of a carboxyl group-modified polyvinyl alcohol ("KL-318" manufactured by Kuraray Co., Ltd.) was dissolved in 100 parts by weight of water to prepare a polyvinyl alcohol aqueous solution. A water-soluble polyamide epoxy resin ("Sumirez Resin 650 (30)", solid content concentration 30% by weight, manufactured by Taoka Kagaku Kogyo Co., Ltd.) was added to the obtained aqueous solution at a ratio of 1.5 parts by weight to 100 parts by weight of water , Thereby obtaining an aqueous adhesive.

&Lt; Example 1 >

In the following procedure, a polarizing plate with a protective film having the same layer configuration as in Fig. 2 was prepared. First, the first protective film 21 is adhered to one side of the polarizer 10 so that the hard coat layer is farther from the polarizer 10, and on the opposite side, And the second protective film 22 was bonded using an adhesive. It was then dried at 80 ° C for 5 minutes and cured at 40 ° C for 168 hours. The obtained polarizing plate had a humidity expansion coefficient of 28 ppm ·% RH ^-1 .

Subsequently, the first pressure-sensitive adhesive layer 31 (having a separate film on its outer surface) was bonded to the side of the second protective film 22 opposite to the polarizer 10 side. The aforementioned protective film A was further bonded to the outer surface of the hard coat layer of the first protective film 21 through the second pressure sensitive adhesive layer to obtain a polarizing plate with a protective film. With respect to the obtained polarizing plate with a protective film, the curl amount was measured according to the above-mentioned method. The results are shown in Table 1.

&Lt; Example 2 >

A polarizing plate with a protective film and its individual pieces were manufactured in the same manner as in Example 1 except that the protective film B was used instead of the protective film A, and the curl amount was measured. The results are shown in Table 1.

&Lt; Comparative Example 1 &

A polarizing plate with a protective film and its individual sheets were produced in the same manner as in Example 1, except that Protect Film C was used instead of Protect Film A, and the curl amount was measured. The results are shown in Table 1.

(Preparation of first protective film (B)) [

Konica Minolta Co., triacetyl cellulose film (thickness of 25 ㎛, trade name "KC2TW" in-plane retardation value R _e = 1.2 ㎚, the thickness retardation value at a wavelength of 590 ㎚ at a wavelength of 590 ㎚ R _th = 1.3 ㎚) of Preparation Were prepared.

(Preparation of third pressure-sensitive adhesive layer)

An organic solvent solution obtained by adding a urethane acrylate oligomer and an isocyanate crosslinking agent to a copolymer of butyl acrylate and acrylic acid was applied to the releasing treatment surface of a separator film made of a polyethylene terephthalate film having a thickness of 38 탆 and subjected to releasing treatment, The coated layer was dried so as to have a thickness of 5 탆 and dried, thereby preparing a third pressure-sensitive adhesive layer having a separate film. The storage elastic modulus of this third pressure-sensitive adhesive layer was 0.40 MPa at 23 占 폚 and 0.18 MPa at 80 占 폚.

&Lt; Example 3 >

First, the first protective film (B) is bonded as a first protective film (21) to the one surface of the polarizer (10) using the water-based adhesive, and the third pressure sensitive adhesive layer Having a separate film) was bonded. Next, after the separate film of the third pressure-sensitive adhesive layer was peeled off, a brightness enhancement film ("Advanced Polarized Film, Version 3" manufactured by 3M Company) having a thickness of 26 탆 was applied to the surface of the third pressure- Respectively. The polarizing plate thus obtained had a humidity expansion coefficient of 9.3 ppm ·% RH ^-1 .

The protective film A was bonded to the outer surface of the brightness enhancement film through the second pressure sensitive adhesive layer to obtain a polarizing plate with a protective film. With respect to the obtained polarizing plate with a protective film, the curl amount was measured according to the above-mentioned method. The results are shown in Table 1.

&Lt; Comparative Example 2 &

A polarizing plate with a protective film and its individual sheets were prepared in the same manner as in Example 3 except that Protect Film C was used instead of Protect Film A and the curl amount was measured. The results are shown in Table 1.

Claims (10)

A polarizing plate including a polarizer, and a protective film laminated on one surface of the polarizing plate,
Wherein the protective film has a moisture permeability of 15 g / (m 2 · 24 hr) or less at a temperature of 40 ° C. and a relative humidity of 90%. The polarizing plate with a protective film according to claim 1, wherein the thickness of the polarizing plate is 125 占 퐉 or less. The polarizing plate with a protective film according to claim 1, wherein the other surface of the polarizing plate is composed of the surface of the first pressure-sensitive adhesive layer. The polarizing plate with a protective film according to claim 1, wherein the protective film comprises a second pressure-sensitive adhesive layer laminated on the one surface and a single-layer base film laminated on the second pressure-sensitive adhesive layer. The polarizing plate with a protective film according to claim 1, wherein the polarizing plate further comprises a protective film laminated on at least one surface of the polarizer through a cured layer of an active energy ray-curable adhesive. The polarizing plate according to claim 1, wherein the other surface of the polarizing plate is composed of a surface of the first pressure-sensitive adhesive layer,
And a separate film laminated on the other surface of the polarizing plate. The polarizing plate according to claim 1, wherein the polarizing plate further comprises an optical film other than the polarizer,
Wherein the protective film is laminated on the surface of the optical film. The polarizing plate with a protective film according to claim 7, wherein the optical film is a brightness enhancement film. The polarizing plate with a protective film according to claim 1, wherein the polarizer has a thickness of 15 탆 or less. A laminate comprising the image display element and the polarizing plate with a protective film according to any one of claims 1 to 9 laminated thereon.

Images