KR20190066562A - Optical laminate and production method therefor - Google Patents

Abstract

The present invention relates to an optical laminate which comprises a protective film, a polarizing plate, one or more retardation layers, and an adhesive layer in order, wherein the protective film satisfies formula: first elastic modulus-second elastic modulus >= 300 MPa. In the formula, the first elastic modulus is tensile modulus in the direction orthogonal to an absorption axis of the polarizing plate at the temperature of 23°C in relative humidity of 55% RH, and the second elastic modulus is the tensile modulus in the direction parallel to the absorption axis of the polarizing plate at the temperature of 23°C in the relative humidity of 55% RH.

Description

[0001] OPTICAL LAMINATE AND PRODUCTION METHOD THEREFOR [0002]

The present invention relates to an optical laminate including a protective film, a polarizing plate, a retardation layer and a pressure-sensitive adhesive layer, and a method for producing the same.

BACKGROUND ART As a polarizing plate used in an image display apparatus such as a liquid crystal display apparatus and an organic EL display apparatus, a polarizing plate made of a polyvinyl alcohol-based resin and a protective film made of triacetylcellulose (TAC) . In recent years, a protective film made of a resin other than TAC has also been used in view of thinning, durability, cost, productivity, and the like (for example, Japanese Patent Laid-Open Publication No. 2004-245925 (Patent Document 1)).

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-245925

The retardation layer and the pressure-sensitive adhesive layer may be laminated on one side of the polarizing plate. Though thinning is required for such a multilayered structure including such a polarizing plate, a thin and rigid multilayered structure, particularly a multi-layered structure obtained by cutting it from a long multilayered structure, tends to cause bowing distortion. In the present specification, this variation is also referred to as " curl ".

The multi-layer structure has a multi-layer structure having a protective film to which a peelable protective film (also referred to as a surface protective film) for adhering the polarizing plate surface (the surface opposite to the side on which the retardation layer and the pressure-sensitive adhesive layer are laminated) It is common to circulate on the market as a structure. Even in a multi-layered structure provided with a protective film, when the thickness is reduced, it tends to cause curling when it is made into a woven fabric.

Hereinafter, the multi-layer structure provided with the protective film, the protective film, the polarizing plate, the retardation layer and the pressure-sensitive adhesive layer in this order is also simply referred to as an "optical laminate".

There are two kinds of curls of the optical laminate, i.e., " static " In the optical laminate, " static " refers to curl with a concave surface on the side of the protective film, and " backlash " means curl with a convex surface on the side of the protective film.

When a counterfeit is generated, a bonding error may occur when bonding each of the green bodies of the optical laminate to an image display element such as a liquid crystal cell or an organic EL element through the pressure sensitive adhesive layer, or air bubbles may be mixed in the interface between the pressure sensitive adhesive layer and the image display element Or the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical laminate in which a counterfeit is suppressed and a manufacturing method thereof.

The present invention provides the following optical laminate and its manufacturing method.

[1] A polarizing plate comprising a protective film, a polarizing plate, a retardation layer of one or more layers, and a pressure-

Wherein the protective film satisfies the following formula (I).

First Modulus - Second Modulus ≥300 MPa (I)

Wherein the first elastic modulus is a tensile elastic modulus in a direction perpendicular to the absorption axis of the polarizing plate at a temperature of 23 캜 and a relative humidity of 55% RH and the second elastic modulus is a temperature of 23 캜 and a relative humidity of 55% RH Is a tensile elastic modulus in a direction parallel to the absorption axis of the polarizing plate in the case of the polarizing plate.

[2] The optical laminate according to [1], wherein the polarizer has a thickness of 110 m or less.

[3] The optical laminate according to [1] or [2], wherein the one or more retardation layers include a retardation layer composed of a cured product of a liquid crystal compound.

[4] A method for producing an optical laminate according to any one of [1] to [3]

A first step of laminating a protective film comprising a region satisfying the following formula (I) on one side of a polarizing plate,

A second step of laminating one or more retardation layers and a pressure-sensitive adhesive layer on a surface opposite to the one surface of the polarizing plate,

A third step of cutting out the optical laminate from the region

Wherein the optical layered body is formed of a resin.

First Modulus - Second Modulus ≥ 300 MPa (I)

Wherein the first elastic modulus is a tensile elastic modulus in a direction perpendicular to the absorption axis of the polarizing plate at a temperature of 23 캜 and a relative humidity of 55% RH and the second elastic modulus is a temperature of 23 캜 and a relative humidity of 55% RH Is a tensile elastic modulus in a direction parallel to the absorption axis of the polarizing plate in the case of the polarizing plate.

[5] The manufacturing method according to [4], wherein the second step includes a step of laminating a laminate including a base film and a retardation layer on the opposite side, and then peeling the base film.

According to the present invention, it is possible to provide an optical laminated body in which a counterfeit is suppressed and a manufacturing method thereof.

1 is a schematic sectional view showing an example of an optical laminate.
2 is a schematic cross-sectional view showing an example of the layer structure of the polarizing plate.
3 is a schematic cross-sectional view showing another example of the layer structure of the polarizing plate.
4 is a flow chart showing a method of manufacturing an optical laminate.
5 is a side view showing an example of a manufacturing process (S101) of a polarizing plate having a protective film.
6 is a schematic view for explaining the manufacturing method of each leaf and the measurement point of the MD curl amount.

≪ Optical laminate &

The optical laminate according to the present invention comprises a protective film, a polarizing plate, a retardation layer of one or more layers, and a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) in this order.

Hereinafter, the optical laminate will be described in detail.

(1) Configuration of optical laminate

1 is a schematic sectional view showing an example of an optical laminate according to the present invention. The optical laminate shown in Fig. 1 comprises a protective film 1; A polarizing plate 2; A first adhesive layer 3a; A first retardation layer (3); A second adhesive layer 4a; A second retardation layer (4); A first pressure sensitive adhesive layer (5); And a separate film 6 in this order.

The first pressure sensitive adhesive layer 5 is defined as the outermost pressure sensitive adhesive layer on the opposite side of the side on which the protective film 1 is laminated in the polarizing plate 2.

The protective film 1 is composed of a base film 40 and a second pressure-sensitive adhesive layer 50 laminated thereon.

When the protective film 1 is composed of the base film 40 and the second pressure-sensitive adhesive layer 50 laminated on the base film 40, the second pressure-sensitive adhesive layer 50 of the protective film 1, Respectively.

According to the present invention, for example, in the optical laminate as shown in Fig. 1, it is possible to suppress the occurrence of backlash with convexity on the side of the protective film (1).

According to the optical laminate suppressed by a counterfeit, there is a problem that a bonding error occurs when bonding to the image display element through the first pressure-sensitive adhesive layer, or air bubbles are mixed in the interface between the first pressure-sensitive adhesive layer and the image display element .

The optical laminate may be a long material or a sheet, but usually the problem of curling is likely to occur in each laminate, so that the optical laminate is preferably a laminate.

In the present specification, the term " perovskite " refers to a film of a smaller size cut out from a film of a larger size (for example, a long strip (strip) film).

Here, the curl of the optical laminate can be classified into two types, namely, "MD Curl" and "TD Curl", in addition to the above-described classification of "static" and "counterfeit". "MD curl" is curl caused by stress (shrinkage force, expansion force, etc.) in the direction parallel to the MD direction of the elongated optical laminate in which the wafers of the optical laminate are cut out.

Specifically, the MD curls were cut out from the elongated optical laminate according to the description of Examples described later, and the sample for measurement was placed on a horizontal stand with its concave side facing up (Curl in the absorption axis direction) in which two corners on a diagonal line of a smaller angle between the measurement axis and the absorption axis direction of the polarizing plate of the measurement sample rise out of two diagonal lines of the measurement sample can do. When the absorption axis direction of the polarizing plate and the MD direction of the protective film are parallel to each other in the polarizing plate having the elongated protective film, the MD Curl is an angle between the MD direction of the elongated optical laminate Can be measured as a curl in which two corners on the smaller diagonal line rise.

The "TD curl" is a curl caused by stress (shrinkage force, expansion force, etc.) in a direction parallel to the TD direction of the elongated optical laminate in which the mica of the optical laminate is cut out.

In the present invention, attention is paid to MD Curl. An adverse effect which can be inhibited by the present invention is MD curses.

The MD direction means the machine direction of the film, that is, the longitudinal direction of the film, and the TD direction means the direction orthogonal to the MD direction.

The layer structure of the optical laminate according to the present invention is not limited to the structure shown in Fig. 1 insofar as it includes a protective film, a polarizing plate, a retardation layer of one or more layers, and an adhesive layer in this order, .

[a] The first adhesive layer 3a and the first retardation layer 3, or the second adhesive layer 4a and the second retardation layer 4 may not be provided.

[b] The first retardation layer 3 may be formed directly on the surface of the polarizing plate 2.

[c] Further, a retardation layer other than the first retardation layer 3 and the second retardation layer 4 may be additionally provided.

[d] Separate film 6 may not be provided.

[e] The protective film 1 may have a single-layer structure.

The length of the elongated optical laminate is, for example, 100 to 20000 m, and preferably 1000 to 10000 m. The width of the elongated optical laminate is, for example, 0.5 to 3 m, preferably 1 to 2.5 m.

The size, shape, and cut angle of the sheet-like optical stacked body are not particularly limited.

Each laminate of the optical laminate is preferably a rectangular shape, more preferably a rectangular shape having long sides and short sides. This rectangular shape is preferably rectangular.

In the case where the shape of each leaf is rectangular, the length of the long side is, for example, 50 mm to 300 mm, preferably 70 mm to 150 mm. The length of the short side is, for example, 30 mm to 200 mm, preferably 40 mm to 100 mm.

Although not particularly limited, when the shape of each leaf is rectangular, when viewed from the side of the protective film 1, the absorption axis direction of the polarizing plate 2 is formed at an angle of 45 degrees with respect to the long side and the short side There may be.

Alternatively, when the shape of each leaf is rectangular, the absorption axis direction of the polarizing plate may be parallel to the long side of the protective film 1 as viewed from the side of the protective film 1, or may be an angle of 90 degrees.

Preferably, the optical laminate (preferably, each laminate of the optical laminate) has no counter-scale measured according to the description of the embodiments described later, more preferably, has a statistical value of 20 mm or less, More preferably a flat amount of 10 mm or less, or a flat state without curl, particularly preferably a flat state without curl.

The optical laminate (preferably, each laminate of the optical laminate) is preferably such that the state of curl is the same as that described above in the constitution having the separate film 6 on the outer side of the first pressure-sensitive adhesive layer 5 , And it is more preferable that the state of curl in the structure having at least the separate film 6 is as described above.

(2) Protective film

(2-1) Construction of Protective Film

The protective film 1 is a film for protecting the surface of the polarizing plate 2 and is usually peeled off in the case where the second pressure sensitive adhesive layer 50 is provided after the optical laminate is bonded to an image display device or the like . Therefore, the protective film 1 is peelably bonded to the surface of the polarizing plate 2.

The protective film 1 can be composed of the base film 40 and the second pressure-sensitive adhesive layer 50 laminated thereon, as described above.

The base film 40 may be formed of a thermoplastic resin such as a polyolefin resin such as a polyethylene resin, a polypropylene resin, and a cyclic polyolefin resin; Polyester resins such as polyethylene terephthalate and polyethylene naphthalate; Polycarbonate resin; (Meth) acrylic resin or the like. The base film 40 may have a single-layer structure or a multi-layer structure.

The second pressure sensitive adhesive layer 50 may be composed of a (meth) acrylic pressure sensitive adhesive, an epoxy pressure sensitive adhesive, a urethane pressure sensitive adhesive, a silicone pressure sensitive adhesive, or the like.

The protective film 1 may be a self-adhesive resin film such as a polypropylene resin or a polyethylene resin. In this case, the protective film 1 does not have the second pressure-sensitive adhesive layer 50.

The thickness of the protective film 1 may be, for example, 5 to 150 占 퐉, preferably 10 to 100 占 퐉, more preferably 20 to 75 占 퐉, and still more preferably 25 to 70 占 퐉 , And further, not more than 55 μm). When the thickness of the protective film 1 is less than 5 占 퐉, the protection of the polarizing plate 2 may be insufficient and the handling property is disadvantageous. The thickness of the protective film 1 exceeding 150 탆 is disadvantageous from the viewpoint of thinning of the optical laminate and the reworkability of the protective film.

(2-2) Elastic modulus of protective film

The protective film (1) of the optical laminate has the following formula (I):

First Modulus - Second Modulus ≥300 MPa (I)

.

In the formula (I), the first elastic modulus is a tensile elastic modulus (MPa) in a direction perpendicular to the absorption axis of the polarizing plate 2 at a temperature of 23 캜 and a relative humidity of 55% RH, (MPa) in a direction parallel to the absorption axis of the polarizing plate 2 at a relative humidity of 50% RH and a relative humidity of 55% RH.

According to the optical laminate having the protective film (1) satisfying the formula (I), it is possible to suppress the occurrence of backlash with the convex surface on the side of the protective film (1).

The direction orthogonal to the absorption axis of the polarizing plate 2 agrees with the TD direction of the protective film 1 and the polarizing plate 2 when the optical laminate is produced by a manufacturing method described later.

The expression " satisfying the formula (I) " means that the first and second elastic moduli satisfy the formula (I) when the protective film is measured according to the description of Examples described later.

From the viewpoint of suppressing the adverse effect of the optical laminate, the left side of the formula (I) is preferably 400 MPa or more, more preferably 500 MPa or more.

Generally, the smaller the size of each leaf, the more likely it is to create a false alarm. Therefore, in the case where the size of each leaf is small, it is preferable that the left side of the formula (I) is made larger in order to sufficiently suppress the backlash.

(3) Polarizer

(3-1) Configuration of Polarizer

The polarizing plate 2 is a polarizing element including at least a polarizer, and usually includes a thermoplastic resin film which is bonded to one side or both sides thereof.

The thermoplastic resin film may be a protective film for protecting the polarizer and the like. When a protective film (thermoplastic resin film) is bonded to the side of the protective film 1 of the polarizing plate 2, the protective film (thermoplastic resin film) may be a retardation film. Further, the following resin layer such as an antireflection treatment layer may be formed on the side of the protective film 1 of the protective film (thermoplastic resin film).

The thermoplastic resin film may have a resin layer (e.g., an optical layer) laminated on its surface. Examples of the resin layer include a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, an antifouling layer, and the like. The resin layer is suitably used particularly for the thermoplastic resin film on the side of the protective film (1).

The thermoplastic resin film can be bonded to the polarizer through the adhesive layer or the pressure-sensitive adhesive layer.

The thickness of the polarizing plate 2 is usually 150 占 퐉 or less and preferably 110 占 퐉 or less, more preferably 80 占 퐉 or less, further preferably 70 占 퐉 or less, from the viewpoint of thinning of the polarizing plate 2. The smaller the thickness of the polarizing plate 2, the easier the curling of the optical laminate. However, according to the present invention, even when the thickness of the polarizing plate 2 is small, it is possible to effectively suppress the backlash of the optical laminate.

The thickness of the polarizing plate 2 is usually 20 占 퐉 or more or 30 占 퐉 or more.

Examples of the layer configuration of the polarizing plate 2 will be described with reference to Figs. 2 and 3. However, the layer configuration is not limited to these examples.

The polarizing plate 2a shown in Fig. 2 comprises a polarizer 10; A first thermoplastic resin film (20) bonded to one surface of the polarizer (10); And a second thermoplastic resin film (30) bonded to the other surface of the polarizer (10). The first and second thermoplastic resin films 20 and 30 are, for example, protective films.

One of the first and second thermoplastic resin films 20 and 30 may be omitted like the polarizing plate 2b shown in Fig. In the polarizing plate 2b, the second thermoplastic resin film 30 is omitted. A polarizing plate having a thermoplastic resin film on only one side of the polarizer 10 is advantageous for thinning the polarizing plate.

Although not shown in Figs. 2 and 3, the polarizer 10 and the first and second thermoplastic resin films 20 and 30 can preferably be bonded using an adhesive.

(3-2) Polarizer

The polarizer 10 constituting the polarizing plate 2 absorbs linearly polarized light having a vibration plane parallel to its absorption axis and transmits the linearly polarized light having a vibration plane perpendicular to the absorption axis (parallel to the transmission axis) Is an absorption type polarizer having An example of the polarizer 10 is a polarizer in which a dichroic dye is adsorbed and aligned on a uniaxially stretched polyvinyl alcohol resin film. This polarizer (10) is, for example, a process 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; A step of treating a polyvinyl alcohol-based resin film adsorbed with a dichroic dye with a crosslinking solution such as an aqueous solution of boric acid; And a step of washing after the treatment with the crosslinking liquid.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. As the polyvinyl acetate resin, a copolymer of vinyl acetate, which is a homopolymer of vinyl acetate, and other monomers copolymerizable with vinyl acetate, and the like can be given. 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.

In the present specification, "(meth) acryl" means at least one selected from acrylic and methacrylic. (Meth) acryloyl ", " (meth) acrylate ", 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 resin may be modified. 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 degree of saponification and the average degree of polymerization of the polyvinyl alcohol-based resin can be determined in accordance with JIS K 6726.

A film of such a polyvinyl alcohol-based resin is used as a raw film of the polarizer 10. The method of forming the polyvinyl alcohol-based resin is not particularly limited, and a known method is employed. The thickness of the polyvinyl alcohol-based resin film is not particularly limited, but is, for example, about 10 to 150 mu m, preferably 50 mu m or less, and more preferably 35 mu m or less.

The uniaxial stretching of the polyvinyl alcohol based resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. In the case of uniaxial stretching after dyeing, the uniaxial stretching may be carried out before or during the crosslinking treatment. In addition, uniaxial stretching may be performed at a plurality of these steps.

In the uniaxial stretching, the uniaxial stretching may be performed between rolls having different circumferential velocities, or may be uniaxially stretched using a heat 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 is 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 crosslinking treatment after dyeing with a dichroic dye, a method of immersing a dyed polyvinyl alcohol resin film in an aqueous solution containing boric acid is usually employed. When iodine is used as the dichroic dye, it is preferable that the aqueous solution containing boric acid contains potassium iodide.

The thickness of the polarizer 10 is usually about 2 to 40 mu m. From the viewpoint of thinning of the polarizing plate 2, the thickness of the polarizer 10 is preferably 20 占 퐉 or less, more preferably 15 占 퐉 or less, and further preferably 10 占 퐉 or less. The thickness of the polarizer 10 is, for example, 10 占 퐉 or more, more preferably 15 占 퐉 or more, particularly 20 占 퐉 or more, although the optical stacked body is liable to cause curling as the polarizer 10 is thicker. A laminate can be provided.

(3-3) The first and second thermoplastic resin films

Each of the first and second thermoplastic resin films 20 and 30 is a film composed of a thermoplastic resin having transparency independently, preferably an optically transparent thermoplastic resin. Examples of the thermoplastic resin constituting the first and second thermoplastic resin films 20 and 30 include a polyolefin resin such as a chain polyolefin resin (polypropylene resin) and a cyclic polyolefin resin (norbornene resin); 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.

Examples of the chain polyolefin 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. More specifically, examples thereof include a polypropylene resin (a polypropylene resin which is a homopolymer of propylene or a copolymer mainly comprising propylene), a polyethylene resin (a polyethylene resin which is a homopolymer of ethylene or a copolymer mainly comprising ethylene) .

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, norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as cyclic olefins are 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 polyester-based resin is a resin other than the cellulose-based resin having an ester bond, and is generally composed of a polycondensation product of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polycarboxylic acid or its derivative, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethylterephthalate, dimethyl naphthalenedicarboxylate and the like. As the polyhydric alcohol, a dihydric diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. Examples of suitable polyester-based resins include polyethylene terephthalate.

The polycarbonate resin is an engineering plastic composed of a polymer having a monomer unit bonded through a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy and transparency. The polycarbonate resin may be a resin called a modified polycarbonate such as a polymer skeleton modified to lower the photoelastic coefficient, or a copolymerized polycarbonate improved in wavelength dependency.

The (meth) acrylic resin is a polymer containing a constituent unit derived from a (meth) acrylic monomer. This polymer is typically a polymer comprising a methacrylic acid 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% by weight or less based on the total structural units.

As the methacrylic acid ester which can constitute the (meth) acrylic resin, a methacrylic acid alkyl 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, Methacrylic acid alkyl esters having 1 to 8 carbon atoms in the alkyl group such as 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and 2-hydroxyethyl methacrylate. 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 that can constitute the (meth) acrylic resin include acrylic ester and other compounds having a polymerizable carbon-carbon double bond in the molecule. The other polymerizable monomers may be used alone, or two or more of them may be used in combination. As the acrylic acid ester, acrylic acid alkyl ester is preferable. Examples of the alkyl acrylate include 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. 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 two or more kinds thereof may be used in combination.

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.

The first and second thermoplastic resin films 20 and 30 may be a protective film for protecting the polarizer 10 laminated on one surface of the polarizer 10. The first or second thermoplastic resin films 20 and 30 may be a protective film having optical functions such as a retardation film and a brightness enhancement film.

For example, a phase difference film having an arbitrary retardation value can be obtained by stretching (uniaxially stretching or biaxially stretching) a thermoplastic resin film made of the above-mentioned material. The first and / or second thermoplastic resin films 20 and 30 may have a surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer and an antifouling layer laminated on the surface thereof .

Thicknesses of the first and second thermoplastic resin films 20 and 30 are usually 1 to 100 占 퐉, but preferably 5 to 60 占 퐉 and more preferably 5 to 50 占 퐉 in view of strength and handling properties.

The smaller the thickness of the first thermoplastic resin film 20 or the second thermoplastic resin film 30 is, the more easily the curled polar body of the polarizing plate provided with the protective film becomes. However, according to the present invention, the first thermoplastic resin film 20, The thickness of the second thermoplastic resin film 30 or the second thermoplastic resin film 30 is, for example, 40 占 퐉 or less, and furthermore, 30 占 퐉 or less.

In the case where the thermoplastic resin film is provided on both sides of the polarizer 10 as in the polarizing plate 2a shown in Fig. 2, these thermoplastic resin films may be composed of the same kind of thermoplastic resin or may be composed of different kinds of thermoplastic resins . The thickness may be the same or different. In the case where the thermoplastic resin films to be bonded to both surfaces have different structures, curl tends to occur in the optical laminate. In such a case, the present invention is particularly advantageous.

(3-4) Adhesive

As described above, the first and second thermoplastic resin films 20 and 30 can be bonded to the polarizer 10 through, for example, an adhesive layer. As the adhesive 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 composed 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 a polyvinyl alcohol-based copolymer obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable therewith, in addition to a vinyl alcohol homopolymer obtained by saponifying a polyvinyl acetate which is a homopolymer of vinyl acetate Or a modified polyvinyl alcohol-based polymer obtained by partially modifying the 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 aqueous adhesive after the polarizer 10 and the first and second thermoplastic resin films 20 and 30 are bonded. After the drying step, a curing step may be performed for curing at a temperature of 20 to 45 占 폚, for example.

The active energy ray-curable adhesive is an adhesive containing a curable compound which is cured by irradiation with active energy rays such as ultraviolet rays, visible rays, electron beams and X-rays, and is preferably an ultraviolet ray curable adhesive.

The curable compound may be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of the cationically polymerizable curable compound include epoxy compounds (compounds having one or two or more epoxy groups in the molecule), oxetane compounds (compounds having one or two or more oxetane rings in the molecule), or combinations thereof . Examples of the radically polymerizable curable compound include (meth) acrylic compounds (compounds having one or more (meth) acryloyloxy groups in the molecule), other vinyl compounds having a radically polymerizable double bond, . ≪ / RTI > A cationically polymerizable curable compound and a radical polymerizable curable compound may be used in combination. The active energy ray-curable adhesive usually further comprises a cationic polymerization initiator and / or a radical polymerization initiator for initiating the curing reaction of the curable compound.

In joining the polarizer 10 and the first and second thermoplastic resin films 20 and 30, at least one of the bonding surfaces may be subjected to a surface activation treatment in order to improve the adhesiveness. Examples of the surface activation treatment include dry treatment such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment and the like), flame treatment, ozone treatment, UV ozone treatment, ionization active ray treatment (ultraviolet radiation treatment, electron beam treatment and the like); Wet treatment such as ultrasonic treatment using a solvent such as water or acetone, saponification treatment, and anchor coat treatment. These surface activation treatments may be performed singly or two or more may be combined.

In the case where the thermoplastic resin film is bonded to both surfaces of the polarizer 10, the adhesive for bonding these thermoplastic resin films may be the same type of adhesive or different types of adhesives.

(4)

The optical laminate includes one or more retardation layers (layers having retardation characteristics) laminated on the opposite side of the side on which the protective film 1 is laminated in the polarizing plate 2. Fig. 1 shows an example having two retardation layers.

In the case where the optical laminate includes two or more retardation layers, these retardation layers may have a slow axis in the same direction or a slow axis in different directions.

The one or more retardation layers contained in the optical laminate may be independently a phase retardation layer (a retardation film) as a film or a layer formed by coating a composition for forming a retardation layer, ).

An example of the retardation layer is a retardation layer (liquid crystal curable retardation layer) composed of a cured product of a liquid crystal compound. In this retardation layer, the liquid crystal compound has a liquid crystal alignment in a predetermined direction, and its alignment is fixed by curing the liquid crystal compound. The liquid crystal alignment in a predetermined direction can be adjusted by the alignment regulating force of the alignment layer described later.

As the liquid crystal compound constituting the retardation layer, it is preferable to use a polymerizable liquid crystal compound having a polymerizable group. By the polymerization reaction of the polymerizable liquid crystal compound, the alignment state of the liquid crystal compound can be fixed. The polymerization reaction of the polymerizable liquid crystal compound may be a thermal polymerization reaction using a thermal polymerization initiator or a photopolymerization reaction using a photopolymerization initiator, but it is preferably a photopolymerization reaction.

The alignment direction of the liquid crystal compound contained in the retardation layer may be regulated by using the alignment layer as described above. When the polymerizable liquid crystal compound is used as the liquid crystal compound, the polymerizable liquid crystal compound is optically aligned And adjusting or enhancing the orientation of the polymerizable liquid crystal compound.

The liquid crystal curable retardation layer can be formed using a known liquid crystal compound. The kind of the liquid crystal compound is not particularly limited, and rod-shaped liquid crystal compounds, discotic liquid crystal compounds, and mixtures thereof can be used.

The one or more retardation layers included in the optical laminate may each independently function as, for example, a half-wave plate, a quarter-wave plate, a positive C plate, a quarter wavelength plate of reverse wavelength dispersion, or the like .

When the optical laminate includes two retardation layers, a combination of the retardation layer and the retardation layer may be a combination of a half-wave plate and a quarter-wave plate, a combination of a positive C plate and a quarter- .

The thickness of the retardation layer is usually from 1 to 100 占 퐉 in the case of a retardation film, but is preferably from 5 to 60 占 퐉, more preferably from 5 to 50 占 퐉 from the viewpoints of strength and handleability.

The thickness of the retardation layer is usually 0.1 to 10 占 퐉, preferably 0.2 to 8 占 퐉, more preferably 0.5 to 5 占 퐉 in the case of a layer formed by coating (coating) like the liquid crystal curing retardation layer.

The retardation layer may be laminated so as to be in direct contact with the adjacent layers or may be laminated via an adhesive layer (for example, the first adhesive layer 3a and the second adhesive layer 4a of the optical laminate shown in Fig. 1).

The adhesive layer may be a layer formed of an adhesive agent or a layer formed of a pressure-sensitive adhesive agent.

Regarding the adhesive, the description of (3-4) is cited. As for the pressure-sensitive adhesive (pressure-sensitive adhesive composition), the description of the following (5) is cited.

(5) The first pressure sensitive adhesive layer

The first pressure sensitive adhesive layer 5 is arranged on the outer side (farther from the polarizing plate 2) than the one or more retardation layers on the side opposite to the side where the protective film 1 is laminated in the polarizing plate 2 And when the optical laminate includes a plurality of pressure-sensitive adhesive layers, it is the outermost pressure-sensitive adhesive layer.

The first pressure-sensitive adhesive layer 5 can be used for bonding the optical laminate to an image display element or another optical member.

The first pressure sensitive adhesive layer 5 can be composed of a pressure sensitive adhesive composition containing as a main component a resin such as (meth) acrylic, rubber, urethane, ester, silicone or polyvinyl ether. Among them, a pressure-sensitive adhesive composition comprising a (meth) acrylic resin having excellent transparency, weather resistance, heat resistance and the like as a base polymer is suitable. The pressure-sensitive adhesive composition may be an active energy radiation curable type or a thermosetting type.

Examples of the (meth) acrylic resin (base polymer) used in the pressure-sensitive adhesive composition include (meth) acrylic acid esters such as (meth) acrylic acid butyl (meth) acrylate, isobutyl (meth) acrylate, A polymer or a copolymer containing one or more of esters as a monomer is suitably used. 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, and monomers having a carboxyl group, 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 cross-linking agent include a metal ion having a valence of 2 or more and forming a carboxylic acid metal salt with a carboxyl group; A polyamine compound, which forms an amide bond with a carboxyl group; A polyepoxy compound or a polyol, which forms an ester bond with a carboxyl group; Is a polyisocyanate compound, and forms an amide bond with a 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 brought into close contact with 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 an ultraviolet curable 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 and the like may be contained.

The pressure-sensitive adhesive composition may contain fine particles for imparting light scattering properties, resins other than beads (resin beads, glass beads, etc.), glass fibers, base polymers, antistatic agents, tackifiers, fillers (metal powders and other inorganic powders) An antioxidant, an ultraviolet absorber, a dye, a pigment, a colorant, a defoaming agent, a corrosion inhibitor, a photopolymerization initiator, and the like.

The first pressure sensitive adhesive layer (5) can be formed by applying an organic solvent diluted solution of the above pressure sensitive adhesive composition onto a substrate and drying it. The substrate may be a retardation layer constituting the optical laminate, a separate film (e.g., separate film 6), 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 5 is usually 1 to 40 占 퐉, but preferably 2 to 30 占 퐉 in view of thinning of the optical laminate.

(6) Separate film

The separate film (release film) 6 is a film temporarily adhered to protect the surface of the first pressure-sensitive adhesive layer 5 until the first pressure-sensitive adhesive layer 5 is bonded to an image display element or another optical member. Normally, the separate film 6 is made of a thermoplastic resin film subjected to a releasing treatment with a release agent such as a silicone type or a fluorine type on one side, and the releasably processed surface is bonded to the first pressure sensitive adhesive layer 5.

The thermoplastic resin constituting the separate film 6 may 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 thickness of the separate film 6 is, for example, 10 to 50 mu m.

≪ Method of producing optical laminate >

4, a method of manufacturing an optical laminate according to the present invention comprises the steps of:

A first step (S101) of laminating a protective film including a region satisfying the formula (I) described later on one side of a polarizing plate to obtain a polarizing plate having a protective film (a step of producing a polarizing plate having a protective film)

Optical laminate manufacturing process (S102)

.

The optical laminate manufacturing process (S102)

A second step of laminating one or more retardation layers and a pressure-sensitive adhesive layer on the surface opposite to the one surface of the polarizing plate in the polarizing plate provided with the obtained protective film, and

A third step of cutting out the optical laminate from the region

.

Hereinafter, each step will be described in detail.

(1) First step

5, a first step (S101) of bonding a polarizing plate 2 and a protective film 1 (a step of producing a polarizing plate having a protective film) is carried out by using a pair of rolls (bonding rolls) 8 and 8 ) Can be used. This method is particularly advantageous when the polarizing plate 2 and the protective film 1 are elongated from the viewpoint of production efficiency.

Therefore, it is preferable that both of the polarizing plate 2 and the protective film 1 provided in the production step (S101) of the polarizing plate with a protective film are elongated.

The length of the elongated polarizing plate 2 and the protective film 1 is, for example, 100 to 20000 m, preferably 1000 to 10000 m. The width of the elongated polarizing plate 2 and the protective film 1 is, for example, 0.5 to 3 m, preferably 1 to 2.5 m.

The protective film (1) provided in the production step (S101) of a polarizing plate with a protective film is represented by the following formula (I):

First Modulus - Second Modulus ≥300 MPa (I)

. This region may be the entire protective film 1 or a part thereof. In the case of a long protective film, the first elastic modulus and the second elastic modulus generally differ from each other in the width direction, but they show substantially the same value in the longitudinal direction.

In the formula (I), the first elastic modulus is a tensile elastic modulus (MPa) in a direction perpendicular to the absorption axis of the polarizing plate 2 at a temperature of 23 캜 and a relative humidity of 55% RH, (MPa) in a direction parallel to the absorption axis of the polarizing plate 2 at a relative humidity of 50% RH and a relative humidity of 55% RH.

The expression " satisfying the formula (I) " means that the first and second elastic moduli satisfy the formula (I) when the protective film is measured according to the description of Examples described later.

From the viewpoint of suppressing the adverse effect of the optical laminate, the left side of the formula (I) is preferably 400 MPa or more, more preferably 500 MPa or more. The left side of the formula (I) is usually not more than 2000 MPa, and typically not more than 1500 MPa.

As the protective film (1) provided in the production step (S101) of the polarizing plate with a protective film, the left side of the formula (I) may be measured with respect to the obtained protective film to use the one satisfying the formula (I).

The polarizing plate 2 and the protective film 1 are bonded to each other by, for example, continuously conveying the elongated polarizing plate 2 and continuously conveying the elongate protective film 1, The protective film 1 is superimposed on one side and passed through a pair of bonding rolls 8 and 8 so that the polarizing plate 7 having a protective film to which both films are bonded can be manufactured.

The MD direction (conveying direction) of the polarizing plate 2 and the MD direction (conveying direction) of the protective film 1 are generally parallel. The parallel means that the angle formed by the MD direction of the polarizing plate 2 and the MD direction of the protective film 1 is 0 degrees +/- 5 degrees, preferably 0 degrees +/- 2 degrees.

It is preferable to bond both films so that the absorption axis of the polarizing plate 2 and the MD direction of the protective film 1 become parallel to each other in order to suppress the adverse effect of the resulting optical laminate. The parallel means that the angle formed between the absorption axis of the polarizing plate 2 and the MD direction of the protective film 1 is 0 degrees +/- 5 degrees, preferably 0 degrees +/- 2 degrees.

The direction orthogonal to the absorption axis of the polarizing plate 2 is the same as the direction perpendicular to the absorption axis of the polarizing plate 2 when the polarizing plate 2 and the polarizing plate 2 are bonded such that the absorption axis of the polarizing plate 2 and the MD direction of the protective film 1 are parallel. TD direction.

By passing the laminated body of the polarizing plate 2 and the protective film 1 between the pair of bonding rolls 8 and 8, the laminated body is pressed in the up and down directions, and both films are brought into close contact with each other.

When the polarizing plate 2 has a clear hard coat layer (hard coat layer having a smooth surface) on its outermost surface and the protective film 1 is bonded to the clear hard coat layer, the polarizing plate 2 and the protect film It is easy to increase the adhesion between the optical fiber 1 and the optical laminate in which a counterfeit is suppressed. Therefore, it is preferable that the polarizing plate 2 has a clear hard coat layer (hard coat layer whose surface is smooth) on its outermost surface.

When the protective film 1 is composed of the base film 40 and the second pressure sensitive adhesive layer 50 laminated on the base film 40, the protective film 1 is superimposed on one side of the polarizing plate 2 to form a pair of bonding rolls 8, 8, the second pressure sensitive adhesive layer 50 of the protective film 1 is overlapped with the one side face of the polarizing plate 2. A corona treatment, an ultraviolet ray irradiation treatment, a flame (flame) treatment, a saponification treatment (oxidation treatment), or the like is applied to the bonding surfaces of at least one of the protective film 1 and the polarizing plate 2 prior to the lamination of the protective film 1 and the polarizing plate 2. [ Surface activation treatment such as treatment may be performed.

The pressure (nip pressure) given to the laminated body of the protective film 1 and the polarizing plate 2 is, for example, 0.01 to 0.5 MPa in the step of joining by the pair of bonding rolls 8 and 8. Even in the case of 0.05 to 0.3 MPa good. As the bonding rolls 8 and 8, conventionally known ones such as a metal surface (including an alloy such as SUS) or a rubber may be used.

In the production step (S101) of a polarizing plate having a protective film, it is preferable to bond both films while applying tension to the polarizing plate 2 and the protective film 1. The tension of the polarizing plate (2) It is more preferable to be smaller than the pre-bonding tension of the film (1). Such tension control is advantageous in suppressing the adverse effect of the resulting optical laminate. The pre-bonding tension refers to the tensile force applied to the film in the MD direction immediately before the two films are bonded (the laminate of both films passes through the pair of bonding rolls 8, 8) Can be measured according to the substrate.

The pre-bonding tension in the MD direction of the polarizing plate 2 is preferably 250 N / m or less, more preferably 200 N / m or less, from the viewpoint of suppressing the adverse effect of the obtained optical laminate.

From the same viewpoint, the pre-bonding tension of the protective film 1 is preferably 260 N / m or more, more preferably 300 N / m or more.

(2) Second step

This step is a step of laminating at least one retardation layer and a first pressure-sensitive adhesive layer 5 on the side opposite to the side where the protective film 1 is laminated in the polarizing plate 2 of the polarizing plate 7 having a protective film Process. A separate film 6 may be further laminated on the outer surface of the first pressure sensitive adhesive layer 5.

The optical laminate obtained in this step is preferably elongated.

The length of the elongated optical laminate is, for example, 100 to 20000 m, and preferably 1000 to 10000 m. The width of the elongated optical laminate is, for example, 0.5 to 3 m, preferably 1 to 2.5 m.

The lamination of the retardation layer to the polarizing plate 7 having a protective film may include a step of laminating a laminate including the base film and the retardation layer on the opposite side and then peeling the base film. This method is advantageous when the retardation layer is a layer formed by coating (coating) the liquid crystal curable retardation layer.

In the case where the step of laminating the retardation layer includes a step of peeling the base film, it is easy for the optical laminate to be counterfeited. However, according to the present invention, even in the case of including the step of peeling the base film, An optical laminate can be produced.

For example, as a method for laminating the first retardation layer 3, which is a layer formed by coating, on the polarizing plate 7 having a protective film, a method including the following step can be mentioned. The second retardation layer 4 can be laminated in the same manner.

[a] a step of forming an alignment layer on a base film,

a step of forming a first retardation layer (3) on the [b] orientation layer to obtain a laminate,

(c) stacking the laminate through a first adhesive layer (3a) on a polarizing plate (7) provided with a protective film, and

[d] A step of peeling the base film.

The orientation layer is not particularly limited as long as it can impart orientations such as horizontal alignment, vertical alignment, hybrid alignment, and oblique alignment to the liquid crystal compound contained in the retardation layer. As the orientation layer, for example, an orientation film made of an orientation polymer, a photo orientation film or a groove orientation film using a photo orientation polymer, and the like, and it is preferable that the photo orientation film is a photo orientation film using a photo orientation polymer.

When the alignment layer is an alignment film formed of an oriented polymer, the alignment regulating force for the liquid crystal compound can be arbitrarily adjusted by the surface state or the rubbing condition. In this case, the orientation layer can be formed by applying a composition containing the orientation polymer and a solvent to the substrate film to remove the solvent, or applying the composition to the base film to remove the solvent, and then performing a known rubbing treatment have.

In the case where the alignment layer is a photo alignment layer using a photo-orientable polymer, an alignment layer can be obtained by applying a composition containing a photo-reactive group-containing polymer or monomer and a solvent onto the base film, removing the solvent, and then irradiating with polarized light. As the polarized light to be irradiated, it is preferable to use polarized ultraviolet light.

The retardation layer is formed by applying a composition for forming a retardation layer containing a liquid crystal compound and a solvent on an alignment layer to remove the solvent and then irradiating ultraviolet rays to align the liquid crystal compound in an alignment state along the alignment regulating force of the alignment layer can do.

As the liquid crystal compound, a polymerizable liquid crystal compound having a polymerizable group is preferably used. The alignment state of the liquid crystal compound can be fixed by the polymerization reaction of the polymerizable liquid crystal compound.

The alignment direction of the liquid crystal compound contained in the retardation layer may be regulated by using the alignment layer as described above. When the polymerizable liquid crystal compound is used as the liquid crystal compound, the polymerizable liquid crystal compound is optically aligned And adjusting or enhancing the orientation of the polymerizable liquid crystal compound.

Thereafter, by carrying out the steps [c] and [d], the retardation layer, which is a layer formed by coating, can be laminated on the polarizing plate 7 provided with a protective film.

On the other hand, when the retardation layer is a retardation film, it is preferable that a long retardation film is prepared and the retardation film is bonded to the opposite side through a bonding layer using a bonding roll.

After one or more retardation layers are laminated on the opposite side of the polarizing plate 2 of the polarizing plate 7 provided with the protective film on which the protective film 1 is laminated and the first pressure sensitive adhesive layer 5 or the first A laminate of the pressure-sensitive adhesive layer (5) and the separate film (6) is further laminated to obtain an optical laminate.

(3) Third step

When the optical laminate obtained in the second process is elongated, it is preferable to cut each leaf from the elongated optical laminate by this process.

Cutting (cutting) can be performed by a conventionally known cutting means such as a cutter for cutting.

With respect to the size, shape, and cut angle of each green body, the description of the above <Optical laminate> (1) is cited.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

In the following examples, the thickness of the polarizing plate and the film, the difference in the modulus of elasticity of the protective film, and the pre-bonding tension in the MD direction of the polarizing plate and the protective film were measured as follows.

(1) thickness of polarizing plate and film

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

(2) The difference in elastic modulus of the protective film

The sample for measuring the modulus of elasticity was sandwiched between upper and lower grippers of a tensile tester (Autograp AG-Xplus tester manufactured by Shimadzu Seisakusho Co., Ltd.) so that the gap between grippers was 5 cm, , A temperature of 23 DEG C and a relative humidity of 55% at a tensile rate of 1 mm / min in the longitudinal direction of the sample for measurement, and the slope of the straight line between 3 and 6 MPa in the obtained stress- , A tensile modulus [MPa] at 23 deg. C and a relative humidity of 55% was calculated. At this time, as the thickness for calculating the stress, the thickness value of biaxially stretched polyethylene terephthalate (base film) alone was used.

The tensile elastic modulus calculated from the measurement of the sample for measurement of the first elastic modulus is the first elastic modulus, and the tensile modulus calculated from the measurement of the sample for measurement of the second elastic modulus is the second elastic modulus.

The first elastic modulus - the second elastic modulus was calculated from the obtained first elastic modulus and second elastic modulus.

Hereinafter, the first elastic modulus-second elastic modulus is simply referred to as &quot; elastic modulus difference &quot;.

(3) Pre-bonding tension in the MD direction of the polarizing plate and the protective film

The film tension [N / m] of the polarizing plate and the protective film running between a pair of bonding rolls for bonding the polarizing plate and the protective film and a pair of nip rolls on the upstream side and nearest to the bonding roll, Was measured using a tension detecting roll provided between the roll and a pair of nip rolls closest to the joining roll to obtain the pre-joining tension in the MD direction.

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

(A) Production of polarizer

The film was uniaxially stretched by a dry method approximately four times while continuously conveying a long polyvinyl alcohol film (average polymerization degree: about 2400, saponification degree: not less than 99.9 mol%, thickness: 30 탆) And then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.1 / 5/100 at 28 ° C for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 10.5 / 7.5 / 100 at 68 ° C for 300 seconds. Subsequently, the film was washed with pure water at 5 占 폚 for 5 seconds and then dried at 70 占 폚 for 180 seconds to obtain an elongated polarizer in which iodine was adsorbed and aligned on the uniaxially stretched polyvinyl alcohol film. The thickness of the polarizer was 13 탆.

(B) Production of Polarizing Plate

The longitudinally polarized polarizer obtained in the step (A) was continuously conveyed, and a long first thermoplastic resin film (trade name "COP25ST-HC", a clear hard coat film manufactured by Nippon Seishi Co., Ltd., a cyclic polyolefin resin (Film having a clear hard coat layer formed on a film, thickness: 29 占 퐉) and a long second thermoplastic resin film (trade name: ZRG20SL, a triacetyl cellulose (TAC) film manufactured by Fuji Film Co., 20 占 퐉] was successively fed and an aqueous adhesive was injected between the polarizer and the first thermoplastic resin film and between the polarizer and the second thermoplastic resin film to pass between the pair of bonding rolls to form the first thermoplastic resin film / A laminated film comprising a water-based adhesive layer / polarizer / water-based adhesive layer / second thermoplastic resin film was obtained.

Subsequently, the obtained laminated film was conveyed, passed through a hot-air dryer, and subjected to heat treatment at 80 DEG C for 300 seconds to dry the water-based adhesive layer to obtain an elongated polarizing plate.

The water-based adhesive was prepared by dissolving a polyvinyl alcohol powder (trade name: "Kosepaima", manufactured by Nippon Gohsei Kagaku Kogyo Co., Ltd., average degree of polymerization: 1100) in hot water at 95 ° C and having a concentration of 3% by weight of polyvinyl alcohol An aqueous solution obtained by mixing 1 part by weight of a cross-linking agent (sodium glyoxylate, manufactured by Nippon Gosei Chemical Industry Co., Ltd.) with respect to 10 parts by weight of polyvinyl alcohol powder was used in the aqueous solution. The thickness of the obtained polarizing plate was 62 탆.

(C) Production of a polarizing plate having an elongated protective film

The elongated polarizing plate obtained in the above (B) was continuously conveyed, and a (meth) acryl-based pressure-sensitive adhesive layer ((b)) was laminated on the elongated protective film (biaxially stretched polyethylene terephthalate (Trade name &quot; AY-4212 &quot;, manufactured by Fujimori Kogyo Co., Ltd.) having a thickness of 20 占 퐉 (thickness: 15 占 퐉) laminated thereon was successively transported and passed between a pair of bonding rolls to press the laminate of the protective film and the polarizing plate up and down , And a polarizer plate having a prolonged protective film was continuously produced.

The protective film was bonded to the surface of the first thermoplastic resin film (clear hard coat film) of the polarizing plate through the pressure-sensitive adhesive layer.

The pressure (nip pressure) given to the laminate of the protective film and the polarizing plate by the bonding roll was 0.1 MPa. At this time, the pre-bonding tension in the MD direction of the polarizing plate was 151 N / m, and the pre-bonding tension in the MD direction of the protective film was 327 N / m.

The manufacturing method of the polarizing plate having the elongated protective films of Examples 1 to 3 and Comparative Examples 1 and 2 is the same except that the protective film used is different (the products are the same but the lot is different).

(D) Fabrication of elongated optical laminate

(Meth) acryl-based pressure-sensitive adhesive layer having a thickness of 5 占 퐉 / liquid crystal-curable retardation layer having a thickness of 2 占 퐉 / a thickness of 5 占 퐉 (thickness) having a thickness of 2 占 퐉 was formed on the polarizing plate of the polarizing plate equipped with the protective film obtained in (C) (Meth) acrylic pressure sensitive adhesive layer / liquid crystal curable retardation layer having a thickness of 1 占 퐉 / 25 占 퐉 thick (meth) acrylic pressure sensitive adhesive layer / polyethylene terephthalate film were laminated in this order to prepare a long optical laminate.

The lamination of the liquid crystal curable retardation layer having a thickness of 2 占 퐉 is carried out by forming an orientation layer and a liquid crystal curable retardation layer on a base film made of triacetylcellulose (TAC) film and then laminating the layered product with a (meth) acrylic pressure sensitive adhesive layer And then the alignment layer and the base film were peeled off to form a laminate.

Similarly, the lamination of the liquid crystal curable retardation layer having a thickness of 1 占 퐉 is carried out by forming an orientation layer and a liquid crystal curable retardation layer on a base film made of a triacetyl cellulose (TAC) film and then laminating this laminate to a (meth) acrylic Cured retardation layer having a thickness of 2 占 퐉 through the pressure-sensitive adhesive layer, and then the alignment layer and the base film were peeled off.

Thereafter, a laminate of a 25 占 퐉 thick (meth) acrylic pressure sensitive adhesive layer and a polyethylene terephthalate film separate film was bonded to the surface of a 1 占 퐉 thick liquid crystal curable retardation layer to prepare a long optical laminate.

The thickness of the obtained elongated optical laminate (excluding the separator film) was 100 占 퐉.

(E) Measurement of the difference in elastic modulus of the protective film

A rectangular piece (small piece) having a length of 100 mm on a long side and a length of 25 mm on a short side was cut out from the center in the width direction of the obtained long optical stack, using a super cutter. The cut was cut so that the long side of the piece was parallel to the TD direction of the long optical laminate, and the short side of the piece was parallel to the MD direction of the long optical laminate. A protective film was peeled off from the small piece to obtain a sample for measurement of the first elastic modulus.

Likewise, a rectangular piece having a long side of 100 mm and a short side of 25 mm was cut out from the elongated optical laminate using a super cutter. However, the cut was cut so that the long side of the piece was parallel to the MD direction of the long optical laminate, and the short side of the piece was parallel to the TD direction of the long optical laminate. In addition, the positions at which the pieces were cut out were such that the position in the width direction in the elongated optical laminate was the same as the sample for measuring the first elastic modulus. The protective film was peeled off from the piece and taken out to obtain a sample for measurement of the second elastic modulus.

The first elastic modulus and the second elastic modulus of the elongated protective film are the same regardless of the cut position in the longitudinal direction, provided that the cut positions in the width direction are the same.

The first elastic modulus, the second elastic modulus and the elastic modulus difference were determined for the sample for measuring the first elastic modulus and the sample for measuring the second elastic modulus according to the above-described method. The results are shown in Table 1.

(F) Fabrication of each laminate of optical laminate

6, the absorption axis 61 of the polarizing plate is 45 degrees with respect to the long side and the short side, as viewed from the side of the protective film, from the elongated optical laminate 60 obtained in (D) (Long side 140 mm x short side 70 mm) was cut out with a super cutter to obtain each laminate of the optical laminate. Each fulcrum 70 was cut at the center in the width direction. The first elastic modulus and the second elastic modulus of the protective film of the each fibrillated body (70) are obtained by measuring the first elastic modulus, the second elastic modulus and the second elastic modulus when the measurement sample is cut out from the elongated optical laminate, The same value.

(G) Measurement of MD curl amount of each laminate of optical laminate

With respect to each of the obtained green laminate 70, the MD curl amount was measured by the following method. The results are shown in Table 1. The cut-off of each green body 70 was cut out immediately after fabricating the elongated optical laminate under an environment of 23 ° C and a relative humidity of 55%.

Each of the furrows 70 was placed on a reference plane (a horizontal plane) with its concave side face up. In this state, the height from the reference plane is measured at each of the two corners 80 on the diagonal line of the smaller diagonal line of the diagonal line of each of the green bodies 70 than the absorption axis direction of the polarizer of each green body 70 , And the MD curl amount [mm] as an average of the heights of the two corners 80 was obtained.

A state in which the side of the protection film is concave has a state in which the film is convex and a state in which the side of the protection film is convex is a state in which it has a counterfeit.

In Table 1, when the value of the MD curl amount is a positive value, it indicates that the value is positive, and when it is a negative value, it indicates that the value is negative. The fact that the amount of MD curl is 0 mm means that the two corners 80 are not raised even when the side of the protection film of each flank member 70 is raised or the opposite side is raised.

Each of the laminated bodies of the optical laminate of Examples 1 to 3 including a protective film satisfying the formula (I) had a counterfeit state and a flat state. After removing the separating film from the wafers of Examples 1 to 3, the MD curl amount was measured in the same manner as in (G) above, and no malfunction was observed.

1: Protective film, 2, 2a, 2b: polarizing plate, 3: first retardation layer, 3a: first adhesive layer, 4: second retardation layer, 4a: second adhesive layer, 5: first pressure- Wherein the polarizer is a polarizer and the polarizer is a polarizer. The polarizing plate according to claim 1, wherein the polarizer is a polarizer. Optical laminate, 61: absorption axis of the polarizing plate, 70: perforated body, 80: corner of each leaf.

Claims (6)

A protective film, a polarizing plate, a retardation layer of one or more layers, and a pressure-sensitive adhesive layer in this order,
Wherein the protective film satisfies the following formula (I).
First Modulus - Second Modulus ≥300 MPa (I)
Wherein the first elastic modulus is a tensile elastic modulus in a direction perpendicular to the absorption axis of the polarizing plate at a temperature of 23 캜 and a relative humidity of 55% RH and the second elastic modulus is a temperature of 23 캜 and a relative humidity of 55% RH Is a tensile elastic modulus in a direction parallel to the absorption axis of the polarizing plate in the case of the polarizing plate. The optical laminate according to claim 1, wherein the thickness of the polarizing plate is 110 占 퐉 or less. The optical laminate according to claim 1, wherein the one or more retardation layers comprises a retardation layer composed of a cured product of a liquid crystal compound. The optical laminate according to claim 2, wherein the one or more retardation layers comprises a retardation layer composed of a cured product of a liquid crystal compound. A method for producing the optical laminate according to any one of claims 1 to 4,
A first step of laminating a protective film comprising a region satisfying the following formula (I) on one side of a polarizing plate,
A second step of laminating one or more retardation layers and a pressure-sensitive adhesive layer on a surface opposite to the one surface of the polarizing plate,
A third step of cutting out the optical laminate from the region
Wherein the optical layered body is formed of a resin.
First Modulus - Second Modulus ≥300 MPa (I)
Wherein the first elastic modulus is a tensile elastic modulus in a direction perpendicular to the absorption axis of the polarizing plate at a temperature of 23 캜 and a relative humidity of 55% RH and the second elastic modulus is a temperature of 23 캜 and a relative humidity of 55% RH Is a tensile elastic modulus in a direction parallel to the absorption axis of the polarizing plate in the case of the polarizing plate. 6. The production method according to claim 5, wherein the second step comprises a step of laminating a laminate including a base film and a retardation layer on the opposite side, and then peeling off the base film.

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