JP2019101269A - Optical laminate and production method therefor - Google Patents

Abstract

To provide an optical laminate and a production method therefor which inhibit reverse curl.SOLUTION: An optical laminate is provided comprising a protection film, a polarizer, one or more retardation layers, and an adhesive layer in this order, where the protection film satisfies the formula: (first elastic modulus)-(second elastic modulus)≥300 MPa. In the formula, the first elastic modulus is the tensile modulus in the direction perpendicular to the absorption axis of the polarizer at the temperature of 23°C and the relative humidity of 55%RH, and the second elastic modulus is the tensile modulus in the direction parallel to the absorption axis of the polarizer at the temperature of 23°C and the relative humidity of 55%RH.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical laminate including a protect film, a polarizing plate, a retardation layer and an adhesive layer, and a method of manufacturing the same.

  As a polarizing plate used for image display devices, such as a liquid crystal display device and an organic electroluminescent display device, what bonded the protective film which consists of triacetyl cellulose (TAC) to the polarizer which consists of polyvinyl alcohol-type resin conventionally with an adhesive agent Is commonly used. In recent years, protective films made of resins other than TAC have come to be used from the viewpoint of thinning, durability, cost, productivity and the like (for example, Patent Document 1).

JP 2004-245925 A

  A retardation layer and an adhesive layer may be laminated on one side of the polarizing plate. Although a reduction in thickness is required for a multilayer structure including such a polarizing plate, a multilayer structure that can be obtained by cutting it out from a thin, stiffness-free multilayer structure, particularly a long multilayer structure The sheet is susceptible to bowing deformation. In this specification, this deformation is also referred to as "curling".

The multilayer structure has a peelable protective film (also called surface protective film) for protecting the surface of the polarizing plate on the surface opposite to the side on which the retardation layer and the pressure-sensitive adhesive layer are laminated. In general, it is marketed as a multilayer structure with a protective film in which is stuck. Also in the multi-layered structure with a protective film, the tendency that curling easily occurs when the sheet is made thin is the same.
Hereinafter, the above-described multilayer structure with a protective film, which includes a protective film, a polarizing plate, a retardation layer, and a pressure-sensitive adhesive layer in this order, is also simply referred to as an “optical laminate”.

There are two types of curl in optical laminates, "positive curl" and "reverse curl". In the optical laminate, "positive curl" refers to a curl in which the surface on the protective film side is concave, and "reverse curl" refers to a curl in which the surface on the protective film side is convex.
When reverse curling occurs, when bonding an individual sheet 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, a bonding error may occur, or the pressure-sensitive adhesive layer It is easy to cause a defect that air bubbles get mixed in the interface between the image display element and the image display element.

  An object of the present invention is to provide an optical laminate with suppressed reverse curl and a method of manufacturing the same.

The present invention provides the following optical laminate and a method for producing the same.
[1] A protective film, a polarizing plate, one or more retardation layers, and an adhesive layer are included in this order,
The optical laminated body in which the said protective film satisfy | fills following formula (I).
1st elastic modulus-2nd elastic modulus 300 300MPa (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 ° C. and a relative humidity of 55% RH, and a second elastic modulus is a temperature of 23 ° C., It is a tensile elastic modulus in a direction parallel to the absorption axis of the polarizing plate at a relative humidity of 55% RH. ]
[2] The optical laminate according to [1], wherein the thickness of the polarizing plate is 110 μm 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 the optical laminate according to any one of [1] to [3],
A first step of laminating a protective film including 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 the side opposite to the one side of the polarizing plate;
A third step of cutting the optical laminate from the region;
A manufacturing method of the above-mentioned optical layered product containing.
1st elastic modulus-2nd elastic modulus 300 300MPa (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 ° C. and a relative humidity of 55% RH, and a second elastic modulus is a temperature of 23 ° C., It is a tensile elastic modulus in a direction parallel to the absorption axis of the polarizing plate at a relative humidity of 55% RH. ]
[5] The manufacturing method according to [4], wherein the second step includes a step of peeling the base film after laminating a laminate including the base film and a retardation layer on the opposite side.

  An optical laminate in which reverse curling is suppressed and a method for producing the same can be provided.

It is a schematic sectional drawing which shows an example of an optical laminated body. It is a schematic sectional drawing which shows an example of the laminated constitution of a polarizing plate. It is a schematic sectional drawing which shows another example of the laminated constitution of a polarizing plate. It is a flowchart which shows the manufacturing method of an optical laminated body. It is a side view which shows an example of a polarizing plate manufacturing process S101 with a protective film. It is the schematic explaining the manufacturing method of a sheet, and the measurement point of MD curl amount.

<Optical laminate>
The optical laminate according to the present invention includes a protect film, a polarizing plate, one or more retardation layers, and a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) in this order.
The optical laminate will be described in detail below.

(1) Configuration of Optical Laminate FIG. 1 is a schematic cross-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; The separate film 6 is provided in this order.
The first pressure-sensitive adhesive layer 5 is defined as the pressure-sensitive adhesive layer disposed on the outermost side on the side of the polarizing plate 2 opposite to the side on which the protective film 1 is laminated.
The protect film 1 is composed of a base film 40 and a second pressure-sensitive adhesive layer 50 laminated thereon.
When the protect film 1 is composed of the base film 40 and the second pressure-sensitive adhesive layer 50 laminated thereon, the second pressure-sensitive adhesive layer 50 of the protect film 1 is in contact with the above-mentioned one surface of the polarizing plate 2 Be stacked.

According to the present invention, for example, in the optical laminated body as shown in FIG. 1, it is possible to suppress the occurrence of reverse curl in which the surface on the side of the protect film 1 is convex.
According to the optical laminate in which the reverse curling is suppressed, when bonding to the image display element via the first pressure-sensitive adhesive layer that it has, a bonding error may occur, or the first pressure-sensitive adhesive layer and the image display element It is possible to suppress the problem that air bubbles get mixed in the interface of

The optical laminate may be a long product or a single leaf, but usually, since the problem of curling tends to occur in the single leaf, the optical laminate is preferably a single leaf. is there.
As used herein, "sheet" refers to smaller sized films cut from larger sized films (e.g., long (strip) films).

Here, the curl of the optical laminate can be classified into two types, “MD curl” and “TD curl”, in addition to the above-mentioned classification of “positive curl” and “reverse curl”. The "MD curl" is a curl caused by a stress (contraction force, expansion force, etc.) in a direction parallel to the MD direction of the long optical laminate from which the sheet of the optical laminate is cut out.
Specifically, in the MD curl, a measurement sample (sheet) is cut out from the elongated optical laminate according to the description in the section of the example described later, and the measurement sample is horizontal with the concave side up Of the two diagonals of the measurement sample when it is placed on a flat table, such that the two diagonal corners with a smaller angle with the direction of the absorption axis of the measurement sample polarizer rise The size can be measured as a curl in the direction. When the absorption axis direction of the polarizing plate is parallel to the MD direction of the protective film in the long polarizing plate with a protective film, the MD curl is the long optical laminate of the two diagonal lines of the measurement sample. It can be measured as a curl that raises two corners on the diagonal with a smaller angle with the MD direction.
The "TD curl" is a curl caused by a stress (contraction force, expansion force, etc.) in a direction parallel to the TD direction of the long optical laminate from which the sheet of the optical laminate is cut out.
The present invention focuses on MD curl. Reverse curl, which can be suppressed by the present invention, refers to reverse curl, which is MD curl.
The MD direction means the machine flow 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 configuration of the optical laminate according to the present invention is not limited to the configuration shown in FIG. 1 as long as it includes a protect film, a polarizing plate, one or more retardation layers, and a pressure sensitive adhesive layer in this order. It may have a layered configuration.
[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] A retardation layer other than the first retardation layer 3 and the second retardation layer 4 may be further included.
[D] The separate film 6 may not be included.
[E] The protect film 1 may have a single layer structure.

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

The size, shape and cutting angle of the optical laminate which is a sheet are not particularly limited.
The sheet of the optical laminate preferably has a rectangular shape, more preferably a rectangular shape having a long side and a short side. This rectangular shape is preferably rectangular.
When the shape of the sheet is rectangular, the length of the long side is, for example, 50 mm to 300 mm, and 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.

There is no particular limitation, but when the shape of the sheet is rectangular, when viewed from the side of the protect film 1, the absorption axis direction of the polarizing plate 2 is 45 degrees with respect to the long side and the short side You may make an angle of.
Alternatively, when the shape of the sheet is rectangular, when viewed from the side of the protect film 1, the absorption axis direction of the polarizing plate may be parallel to the long side, or an angle of 90 degrees It may be done.

The optical laminate (preferably, a sheet of the optical laminate) preferably does not have a reverse curl measured according to the description of the example section described later, and more preferably, the amount of positive curl is 20 mm or less Or flat without curl, more preferably 10 mm or less in positive curl, or flat without curl, particularly preferably flat without curl It is a state.
The optical laminate (preferably a sheet of the optical laminate) preferably has at least the curled state as described above in a configuration having or not having the separate film 6 on the outside of the first pressure-sensitive adhesive layer 5 In the configuration having the separate film 6, the curled state is more preferably as described above.

(2) Protecting Film (2-1) Structure of Protecting Film Protecting film 1 is a film for protecting the surface of polarizing plate 2, and usually, for example, after an optical laminate is attached to an image display element or the like. When the second pressure-sensitive adhesive layer 50 is provided, the entire pressure-sensitive adhesive layer is peeled off. Therefore, the protect film 1 is releasably bonded to the surface of the polarizing plate 2.

The protect film 1 can be comprised by the base film 40 and the 2nd adhesive layer 50 laminated | stacked on it as mentioned above.
The base film 40 is a thermoplastic resin, for example, a polyolefin resin such as a polyethylene resin, a polypropylene resin, or a cyclic polyolefin resin; a polyester resin such as polyethylene terephthalate or polyethylene naphthalate; a polycarbonate resin; (meth) acrylic It can be composed of a base resin or the like. The base film 40 may have a single layer structure or a multilayer structure.
The second pressure-sensitive adhesive layer 50 can be composed of a (meth) acrylic pressure-sensitive adhesive, an epoxy-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, or the like.
Further, the protect film 1 may be a resin film having self-adhesiveness, such as a polypropylene resin and a polyethylene resin. In this case, the protect film 1 does not have the second pressure-sensitive adhesive layer 50.

  The thickness of the protect film 1 can be, for example, 5 to 150 μm, preferably 10 to 100 μm, more preferably 20 to 75 μm, and still more preferably 25 to 70 μm (eg 60 μm or less, further 55 μm or less) It is. If the thickness of the protective film 1 is less than 5 μm, the protection of the polarizing plate 2 may be insufficient, and the handling is also disadvantageous. If the thickness of the protective film 1 exceeds 150 μm, it is disadvantageous in terms of thinning of the optical laminate and rework of the protective film.

(2-2) Elastic Modulus of Protecting Film The protecting film 1 provided in the optical laminate has the following formula (I):
1st elastic modulus-2nd elastic modulus 300 300MPa (I)
Meet.
In the formula (I), the first elastic modulus is a tensile elastic modulus (MPa) in a direction orthogonal to the absorption axis of the polarizing plate 2 at a temperature of 23 ° C. and a relative humidity of 55% RH, and a second elastic modulus The tensile elastic modulus (MPa) in the direction parallel to the absorption axis of the polarizing plate 2 at a temperature of 23 ° C. and a relative humidity of 55% RH.
According to the optical laminate including the protect film 1 satisfying the formula (I), it is possible to suppress the occurrence of reverse curl in which the surface on the protect film 1 side is convex.

  The direction orthogonal to the absorption axis of the polarizing plate 2 is, for example, the same as the TD direction of the protective film 1 and the polarizing plate 2 when the optical laminated body is manufactured by a manufacturing method described later.

  “Satisfying the formula (I)” means that the first elastic modulus and the second elastic modulus satisfy the formula (I) when measured in accordance with the description of the section of the examples described later.

From the viewpoint of suppressing the reverse curl of the optical laminate, the left side of Formula (I) is preferably 400 MPa or more, and more preferably 500 MPa or more.
In the case of a single sheet, in general, the smaller the size, the more likely reverse curling occurs. Therefore, when the size of the sheet is small, it may be preferable to make the left side of Formula (I) larger in order to sufficiently suppress reverse curl.

(3) Polarizing Plate (3-1) Configuration of Polarizing Plate The polarizing plate 2 is a polarizing element including at least a polarizer, and usually further includes a thermoplastic resin film bonded to one side or both sides thereof.
The thermoplastic resin film can be a protective film or the like that protects the polarizer. 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. In addition, on the side of the protective film 1 of the protective film (thermoplastic resin film), the following resin layer such as an antireflective treatment layer may be provided.
The thermoplastic resin film may be provided with a resin layer (for example, an optical layer) laminated on the surface thereof. Examples of the resin layer are a hard coat layer, an antiglare layer, an antireflective 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 protect 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 μm or less, preferably 110 μm or less, more preferably 80 μm or less, and still more preferably 70 μm or less from the viewpoint of reducing the thickness of the polarizing plate 2. The smaller the thickness of the polarizing plate 2, the more easily the optical laminate curls. However, according to the present invention, even when the thickness of the polarizing plate 2 is small, the reverse curl of the optical laminate can be effectively suppressed. it can.
The thickness of the polarizing plate 2 is usually 20 μm or more or 30 μm or more.

Although the example of a layer structure of the polarizing plate 2 is demonstrated with reference to FIG.2 and FIG.3, a layer structure is not limited to these examples.
The polarizing plate 2a shown in FIG. 2 includes a polarizer 10; a first thermoplastic resin film 20 bonded to one surface of the polarizer 10; and a second thermoplastic resin bonded to the other surface of the polarizer 10 A resin film 30 is provided. The first and second thermoplastic resin films 20 and 30 are, for example, protective films.

  As in the polarizing plate 2b shown in FIG. 3, one of the first and second thermoplastic resin films 20 and 30 may be omitted. In the polarizing plate 2b, the second thermoplastic resin film 30 is omitted. A polarizing plate having a thermoplastic resin film only on one side of such a polarizer 10 is advantageous for thinning the polarizing plate.

  Although illustration is abbreviate | omitted in FIG.2 and FIG.3, bonding of the polarizer 10 and the 1st and 2nd thermoplastic resin films 20 and 30 can be preferably performed using an adhesive agent.

(3-2) Polarizer The polarizer 10 constituting the polarizing plate 2 absorbs linearly polarized light having a vibration plane parallel to the absorption axis, and has a vibration plane orthogonal to the absorption axis (parallel to the transmission axis). It is an absorptive polarizer having the property of transmitting linearly polarized light. An example of the polarizer 10 is a polarizer in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol-based resin film. In such a polarizer 10, for example, a step of uniaxially stretching a polyvinyl alcohol-based resin film; a step of adsorbing a dichroic dye by dyeing a polyvinyl alcohol-based resin film with a dichroic dye; a dichroic dye It can be manufactured by a method including the steps of treating the adsorbed polyvinyl alcohol resin film with a crosslinking solution such as boric acid aqueous solution; and washing with water after treatment with the crosslinking solution.

  As polyvinyl alcohol-type resin, what saponified polyvinyl acetate type resin can be used. Examples of polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, (meth) acrylamides having an ammonium group, and the like.

  In the present specification, “(meth) acrylic” means at least one selected from acrylic and methacrylic. The same applies to “(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-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The average degree of polymerization of the polyvinyl alcohol resin is usually 1000 to 10000, and preferably 1500 to 5000.
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.

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of the polarizer 10. The method of forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a known method is adopted. Although the thickness in particular of a polyvinyl alcohol-type resin film is not restrict | limited, For example, it is about 10-150 micrometers, Preferably it is 50 micrometers or less, More preferably, it is 35 micrometers or less.

  The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after the dyeing of the dichroic dye. If uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during the crosslinking process. Moreover, you may uniaxially stretch in these several steps.

  In uniaxial stretching, uniaxial stretching may be performed between rolls having different peripheral speeds, or uniaxial stretching may be performed using a heat roll. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which stretching is performed in a state in which a polyvinyl alcohol resin film is swollen using a solvent or water. The stretching ratio is usually 3 to 8 times.

  As a method of 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. The polyvinyl alcohol-based resin film is preferably subjected to immersion treatment in water prior to the dyeing treatment.

  As a crosslinking process after dyeing | staining by a dichroic dye, the method of immersing the dyed polyvinyl alcohol-type resin film in boric-acid containing aqueous solution is employ | adopted normally. When using iodine as a dichroic dye, it is preferable that this boric-acid containing aqueous solution contains potassium iodide.

  The thickness of the polarizer 10 is usually about 2 to 40 μm. From the viewpoint of reducing the thickness of the polarizing plate 2, the thickness of the polarizer 10 is preferably 20 μm or less, more preferably 15 μm or less, and still more preferably 10 μm or less. The thicker the polarizer 10, the easier it is for the optical laminate to curl. However, according to the present invention, the thickness of the polarizer 10 is, for example, 10 μm or more, 15 μm or more, particularly 20 μm or more. An optical laminate with reduced curl can be provided.

(3-3) First and Second Thermoplastic Resin Films The first and second thermoplastic resin films 20 and 30 are each independently a translucent thermoplastic resin, preferably optically transparent heat. It is a film composed of a plastic resin. The thermoplastic resin constituting the first and second thermoplastic resin films 20 and 30 is, for example, a polyolefin resin such as a chain-like polyolefin resin (polypropylene resin etc.) or cyclic polyolefin resin (norbornene resin etc.) Cellulose resins such as triacetyl cellulose and diacetyl cellulose; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate resins; (meth) acrylic resins such as methyl methacrylate resin; polystyrene resins; Polyvinyl chloride resin; acrylonitrile butadiene styrene resin; acrylonitrile styrene resin; polyvinyl acetate resin; polyvinylidene chloride resin; polyamide resin; polyacetal resin; modified polyphenylene Ether-based resins; polysulfone resins; poly (ether sulfone) resins; polyarylate resin; polyamideimide resin; may be a polyimide resin or the like.

  Examples of linear polyolefin resins include homopolymers of linear olefins such as polyethylene resins and polypropylene resins, and copolymers of two or more types of linear olefins. More specific examples are polypropylene resins (polypropylene resins which are homopolymers of propylene, copolymers mainly composed of propylene), polyethylene resins (polyethylene resins which are homopolymers of ethylene), and ethylene (Copolymer)).

  Cyclic polyolefin resin is a general term for resin polymerized as cyclic olefin as a polymerization unit. Specific examples of cyclic polyolefin resins include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and linear olefins such as ethylene and propylene (typically Are random copolymers), graft polymers obtained by modifying these with unsaturated carboxylic acids and derivatives thereof, and hydrides thereof. Among them, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer as the cyclic olefin is preferably used.

  Cellulose-based resin means that part or all of hydrogen atoms in hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linta and wood pulp (hardwood pulp, softwood pulp) are substituted with acetyl group, propionyl group and / or butyryl group Or cellulose organic acid ester or cellulose mixed organic acid ester. For example, those composed of cellulose acetate, propionate, butyrate, mixed esters thereof and the like can be mentioned. Among them, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate and cellulose acetate butyrate are preferable.

  The polyester-based resin is a resin other than the above-mentioned cellulose-based resin having an ester bond, and is generally made of a polycondensate of polyvalent carboxylic acid or derivative thereof and polyvalent alcohol. Divalent dicarboxylic acid or its derivative can be used as polyvalent carboxylic acid or its derivative, For example, a terephthalic acid, an isophthalic acid, a dimethyl terephthalate, dimethyl naphthalene dicarboxylic acid etc. are mentioned. Divalent diol can be used as polyhydric alcohol, For example, ethylene glycol, propanediol, butanediol, neopentyl glycol, cyclohexane dimethanol etc. are mentioned. Examples of suitable polyester-based resins include polyethylene terephthalate.

  A polycarbonate-based resin is an engineering plastic comprising a polymer in which monomer units are bonded via a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy, and transparency. The polycarbonate-based resin may be a resin called a modified polycarbonate in which the polymer skeleton is modified to lower the photoelastic coefficient, or a copolymerized polycarbonate having a wavelength dependency improved.

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

  As a methacrylic acid ester which can comprise a (meth) acrylic-type resin, methacrylic acid alkyl ester is preferable. Examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, and cyclohexyl methacrylate And methacrylic acid alkyl esters having 1 to 8 carbon atoms in the alkyl group such as 2-hydroxyethyl methacrylate. The carbon number of the alkyl group contained in the methacrylic acid alkyl ester is preferably 1 to 4. In the (meth) acrylic resin, only one kind of methacrylic acid ester may be used alone, or two or more kinds thereof may be used in combination.

  As said other polymerizable monomer which can comprise (meth) acrylic-type resin, acrylic acid ester and the compound which has a polymerizable carbon-carbon double bond in another molecule can be mentioned. The other polymerizable monomers may be used alone or in combination of two or more. As acrylic acid ester, acrylic acid alkyl ester is preferable. As acrylic acid alkyl ester, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate And alkyl acrylates having 1 to 8 carbon atoms in the alkyl group such as 2-hydroxyethyl acrylate. The carbon number of the alkyl group contained in the acrylic acid alkyl ester is preferably 1 to 4. In the (meth) acrylic resin, only one acrylic ester may be used alone, or two or more acrylic esters may be used in combination.

  Examples of the compound having a polymerizable carbon-carbon double bond in another molecule include vinyl compounds such as ethylene, propylene and styrene, and vinyl cyan compounds such as acrylonitrile. The compound which has a polymerizable carbon-carbon double bond in another molecule may be used individually by 1 type, and may use 2 or more types together.

The first and second thermoplastic resin films 20 and 30 can be protective films for protecting the polarizer 10, which are laminated and bonded to one surface of the polarizer 10. The first and second thermoplastic resin films 20 and 30 can also be protective films having an optical function such as a retardation film and a brightness enhancement film.
For example, the retardation film to which an arbitrary retardation value is imparted can be obtained by stretching (uniaxial stretching, biaxial stretching, etc.) the thermoplastic resin film made of the above-mentioned material. The first and / or second thermoplastic resin films 20 and 30 are laminated on the surface thereof, such as a hard coat layer, an antiglare layer, an antireflective layer, an antistatic layer, and a surface treatment layer such as an antifouling layer (coating Layer) may be included.

The thickness of the first and second thermoplastic resin films 20 and 30 is usually 1 to 100 μm, but is preferably 5 to 60 μm and more preferably 5 to 50 μm from the viewpoint of strength and handleability.
The smaller the thickness of the first thermoplastic resin film 20 or the second thermoplastic resin film 30, the easier it is for the sheet with protective film to curl, but according to the present invention, the first thermoplastic resin film 20 Or, even if the thickness of the second thermoplastic resin film 30 is as thin as, for example, 40 μm or less, and further 30 μm or less, it is possible to provide an optical laminate in which the reverse curl is suppressed.

  In the case where thermoplastic resin films are provided on both sides of the polarizer 10 as in the polarizing plate 2a shown in FIG. 2, these thermoplastic resin films may be made of the same type of thermoplastic resin, or different types of thermoplastic resin films. It may be composed of a thermoplastic resin of Also, the thickness may be the same or different. The present invention is particularly advantageous in such a case because curling is likely to occur in the optical laminate if the configurations of the thermoplastic resin films bonded on both sides are different.

(3-4) Adhesive As mentioned above, the 1st, 2nd thermoplastic resin films 20 and 30 can be pasted together to light polarizer 10, for example via an adhesive layer. As an adhesive for forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive or a thermosetting adhesive can be used, and a water-based adhesive and an active energy ray-curable adhesive are preferable.

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

  When using a water-based adhesive, after bonding the polarizer 10 and the first and second thermoplastic resin films 20 and 30, a drying step is performed to remove water contained in the water-based adhesive. Is preferred. After the drying step, a curing step of curing at a temperature of, for example, 20 to 45 ° C. may be provided.

  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 light, electron beams, and X-rays, and is preferably an ultraviolet ray-curable adhesive. is there.

  The curable compound can be a cationically polymerizable curable compound or a radically polymerizable curable compound. As the cationically polymerizable curable compound, for example, an epoxy compound (a compound having one or more epoxy groups in the molecule) or an oxetane compound (one or more oxetane rings in the molecule) And compounds thereof, 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) and radically polymerizable double bonds. Other vinyl compounds or combinations thereof can be mentioned. The cationically polymerizable curable compound and the radically polymerizable curable compound may be used in combination. The active energy ray curable adhesive usually further contains a cationic polymerization initiator and / or a radical polymerization initiator for initiating the curing reaction of the curable compound.

  When bonding the polarizer 10 and the first and second thermoplastic resin films 20 and 30, at least one of these bonding surfaces may be subjected to surface activation treatment in order to enhance the adhesion. Good. As surface activation treatment, 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 treatment, electron beam treatment, etc.) Ultrasonic treatment using a solvent such as water or acetone, wet treatment such as saponification treatment, anchor coating treatment can be mentioned. These surface activation treatments may be performed alone or in combination of two or more.

  When thermoplastic resin films are bonded to both sides of the polarizer 10, the adhesive for bonding these thermoplastic resin films may be the same kind of adhesive or different kind of adhesive. May be

(4) Retardation Layer The optical laminate includes one or more retardation layers (layers having retardation properties) laminated on the side opposite to 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, those retardation layers may have slow axes in the same direction, or have slow axes in different directions from each other. It is also good.

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

An example of the retardation layer is a retardation layer (liquid crystal curing retardation layer) composed of a cured product of a liquid crystal compound. In the retardation layer, the liquid crystal compound has liquid crystal alignment in a predetermined direction, and the alignment is fixed by curing of 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 forming 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 a photopolymerization reaction is preferable.
The alignment direction of the liquid crystal compound contained in the retardation layer may be regulated using the alignment layer as described above, but in the case of using a polymerizable liquid crystal compound as the liquid crystal compound, polymerization is performed by irradiating polarized light. It can also be adjusted by photo-orienting the liquid crystal compound to express or improve the orientation of the polymerizable liquid crystal compound.

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

One or more retardation layers contained in the optical laminate are each independently, for example, as a half wave plate, a quarter wave plate, a positive C plate, a quarter wave plate with reverse wavelength dispersion, etc. It can be functional.
When the optical laminate includes two retardation layers, the combination thereof is a combination of a half wave plate and a quarter wave plate, a positive C plate and a quarter wave plate having reverse wavelength dispersion. Combinations of

The thickness of the retardation layer is usually 1 to 100 μm in the case of a retardation film, but is preferably 5 to 60 μm, more preferably 5 to 50 μm from the viewpoint of strength and handleability.
The thickness of the retardation layer is usually 0.1 to 10 μm, preferably 0.2 to 8 μm, in the case of a layer formed by coating (coating) like a liquid crystal curing retardation layer. More preferably, it is 0.5-5 micrometers.

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). It may be
The adhesive layer may be a layer formed of an adhesive or may be a layer formed of an adhesive.
The description of (3-4) above is cited for the adhesive. As for the pressure-sensitive adhesive (pressure-sensitive adhesive composition), the description of (5) below is cited.

(5) First Pressure-Sensitive Adhesive Layer The first pressure-sensitive adhesive layer 5 is located outside the above-mentioned one or more retardation layers on the side opposite to the side where the protective film 1 is laminated on the polarizing plate 2 (from the polarizing plate 2 When the optical laminate includes a plurality of pressure-sensitive adhesive layers, it is the pressure-sensitive adhesive layer disposed on the outermost side.
The 1st adhesive layer 5 can be used in order to bond an optical laminated body 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 a resin such as (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 excellent in transparency, weather resistance, heat resistance and the like as a base polymer is preferable. The pressure-sensitive adhesive composition may be active energy ray curable or thermosetting.

  Examples of the (meth) acrylic resin (base polymer) used in the pressure-sensitive adhesive composition include butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and (meth) acrylic acid 2- (2-) The polymer or copolymer which makes 1 type, or 2 or more types of (meth) acrylic acid esters like ethylhexyl a monomer is used suitably. It is preferable to copolymerize a polar monomer to the base polymer. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, glycidyl Examples thereof include monomers having a carboxyl group, a hydroxyl group, an amido group, an amino group, an epoxy group and the like, such as meta) acrylate.

  The pressure-sensitive adhesive composition may contain only the above-mentioned base polymer, but usually further contains a crosslinking agent. The crosslinking agent is a divalent or higher metal ion which forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound which forms an amide bond with a carboxyl group; poly Examples thereof include epoxy compounds and polyols which form an ester bond with a carboxyl group; and polyisocyanate compounds which form an amide bond with a carboxyl group. Among these, polyisocyanate compounds are preferable.

  An active energy ray-curable pressure-sensitive adhesive composition has the property of being cured by irradiation with active energy rays such as ultraviolet rays and electron beams, and has adhesiveness even before active energy ray irradiation. Etc., and is a pressure-sensitive adhesive composition having a property of being cured by irradiation of active energy rays and capable of adjusting adhesion. The active energy ray-curable pressure-sensitive adhesive composition is preferably ultraviolet-curable. 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. Furthermore, a photopolymerization initiator, a photosensitizer, etc. can also be contained as needed.

  The pressure-sensitive adhesive composition includes fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, antistatic agents, tackifiers, fillers (metal powder and the like) Other inorganic powders and the like), additives such as antioxidants, ultraviolet light absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, and photopolymerization initiators can be included.

  The first pressure-sensitive adhesive layer 5 can be formed by applying an organic solvent dilution liquid of the above-mentioned pressure-sensitive adhesive composition on a substrate and drying it. The substrate can be a retardation layer constituting the optical laminate, a separate film (for example, separate film 6), or the like. When an active energy ray-curable pressure-sensitive adhesive composition is used, the formed pressure-sensitive adhesive layer can be irradiated with active energy rays to obtain a cured product having a desired degree of curing.

  The thickness of the first pressure-sensitive adhesive layer 5 is usually 1 to 40 μm, but is preferably 2 to 30 μm from the viewpoint of thinning of the optical laminate and the like.

(6) Separate film The separate film (release film) 6 is a film temporarily attached to protect the surface of the first pressure-sensitive adhesive layer 5 until it is bonded to the image display element or another optical member. The separate film 6 is usually made of a thermoplastic resin film on one side of which release treatment with a silicone or fluorine release agent is performed, and the release treatment side is bonded to the first pressure-sensitive adhesive layer 5. Ru.

  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 μm.

<Method of Manufacturing Optical Laminate>
Referring to FIG. 4, the method for producing an optical laminate according to the present invention includes the following steps:
A first step (a step of producing a polarizing plate with a protective film) of laminating a protective film including a region satisfying formula (I) described later on one side of a polarizing plate to produce a polarizing plate with a protective film S101, and an optical laminate production step S102
including.
Preferably, the optical laminate manufacturing step S102
The second step of laminating one or more retardation layers and a pressure-sensitive adhesive layer on the side opposite to the one side of the polarizing plate in the obtained polarizing plate with a protective film, and the optical laminate from the above region It includes the third step of cutting out.
Each step will be described in detail below.

(1) First Step Referring to FIG. 5, a first step (a step of manufacturing a polarizing plate with a protective film) S101 for bonding polarizing plate 2 and protective film 1 is, for example, a pair of rolls (bonding rolls) 8 , 8 can be used. This method is particularly advantageous in the case where the polarizing plate 2 and the protect film 1 are long from the viewpoint of production efficiency.
Therefore, it is preferable that the polarizing plate 2 and the protective film 1 which are provided to the protective film-including polarizing plate manufacturing step S101 are both long.

  The length of the long polarizing plate 2 and the protect film 1 is, for example, 100 to 20,000 m, and preferably 1,000 to 10,000 m. The width of the elongated polarizing plate 2 and the protect film 1 is, for example, 0.5 to 3 m, and preferably 1 to 2.5 m.

The protect film 1 to be provided in the step S101 of producing a polarizing plate with a protect film has the following formula (I):
1st elastic modulus-2nd elastic modulus 300 300MPa (I)
Including the region that satisfies This area may be the whole or part of the protect film 1. In the case of a long protective film, usually, the first elastic modulus and the second elastic modulus may be different in the width direction, but show substantially the same value in the length direction.
In the formula (I), the first elastic modulus is a tensile elastic modulus (MPa) in a direction orthogonal to the absorption axis of the polarizing plate 2 at a temperature of 23 ° C. and a relative humidity of 55% RH, and a second elastic modulus The tensile elastic modulus (MPa) in the direction parallel to the absorption axis of the polarizing plate 2 at a temperature of 23 ° C. and a relative humidity of 55% RH.

  “Satisfying the formula (I)” means that the first elastic modulus and the second elastic modulus satisfy the formula (I) when measured in accordance with the description of the section of the examples described later.

  From the viewpoint of suppressing the reverse curl of the optical laminate, the left side of Formula (I) is preferably 400 MPa or more, and more preferably 500 MPa or more. The left side of the formula (I) is usually at most 2000 MPa, and typically at most 1500 MPa.

  As the protect film 1 to be provided in the step S101 of producing a polarizing plate with a protect film, the left side of the formula (I) of the obtained protect film may be measured and the one satisfying the formula (I) may be used.

  Bonding of the polarizing plate 2 and the protect film 1 is, for example, continuously conveying the long polarizing plate 2 and continuously conveying the long protective film 1. By overlapping the protective film 1 and inserting it between a pair of bonding rolls 8 and 8, it is possible to manufacture a protective film-attached polarizing plate 7 in which both films are bonded.

The MD direction (conveying direction) of the polarizing plate 2 and the MD direction (conveying direction) of the protective film 1 are generally parallel. Parallel means that the angle between the MD direction of the polarizing plate 2 and the MD direction of the protect film 1 is 0 ° ± 5 °, preferably 0 ° ± 2 °.
It is preferable to bond both films so that the absorption axis of polarizing plate 2 and MD direction of protection film 1 may become parallel from a viewpoint of controlling reverse curl of an optical layered product obtained. Parallel means that the angle between the absorption axis of the polarizing plate 2 and the MD direction of the protect film 1 is 0 ° ± 5 °, preferably 0 ° ± 2 °.
When pasting both films so that the absorption axis of polarizing plate 2 and the MD direction of protection film 1 become parallel, the direction orthogonal to the absorption axis of polarizing plate 2 is the TD direction of protection film 1 and polarizing plate 2 It is synonymous with

When the laminate of the polarizing plate 2 and the protect film 1 is passed between the pair of bonding rolls 5 and 5, the laminate is pressed from above and below, so both films are in close contact.
When the polarizing plate 2 has a clear hard coat layer (a hard coat layer having a smooth surface) on the outermost surface, and the protective film 1 is bonded to the clear hard coat layer, the polarizing plate 2 and the protective film There is a tendency that an adhesion between the resin and No. 1 can be easily increased, whereby an optical laminate with reduced reverse curl can be easily obtained. Therefore, the polarizing plate 2 preferably has a clear hard coat layer (a hard coat layer having a smooth surface) on the outermost surface thereof.

  When the protect film 1 is composed of the base film 40 and the second pressure-sensitive adhesive layer 50 laminated thereon, the protect film 1 is superposed on one side of the polarizing plate 2 and the space between the pair of bonding rolls 8 and 8 is When passing through, the second pressure-sensitive adhesive layer 50 of the protect film 1 is overlapped so as to be in contact with the one side of the polarizing plate 2. Prior to lamination of the protective film 1 and the polarizing plate 2, the bonding surface of at least one of the protective film 1 and the polarizing plate 2 is subjected to plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, saponification treatment Such surface activation treatment may be performed.

  The pressure (nip pressure) applied to the laminate of the protect film 1 and the polarizing plate 2 in the step of bonding by the pair of bonding rolls 8 and 8 is, for example, 0.01 to 0.5 MPa, 0.05 -0.3MPa may be sufficient. As the bonding rolls 8 and 8, conventionally known ones such as those made of metal (including an alloy such as SUS) or rubber may be used.

  In the protective film-provided polarizing plate production step S101, it is preferable to bond the two films while applying tension to the polarizing plate 2 and the protective film 1, and the tension before bonding of the polarizing plate 2 is the bonding of the protective film 1 It is more preferable that it be smaller than the front tension. Such tension control is advantageous in suppressing the reverse curl of the obtained optical laminate. The tension before bonding means the tension applied in the MD direction of the film before the bonding of both films (the laminate of both films passes through the pair of bonding rolls 8 and 8), and the item of the embodiment described later It can measure according to description of.

The tension before bonding in the MD direction of the polarizing plate 2 is preferably 250 N / m or less, and more preferably 200 N / m or less, from the viewpoint of suppressing reverse curl of the obtained optical laminate.
From the same viewpoint, the tension before bonding in the MD direction of the protect film 1 is preferably 260 N / m or more, and more preferably 300 N / m or more.

(2) Second step In this step, one or more retardation layers and the first pressure-sensitive adhesive layer 5 are provided on the side of the polarizing plate 2 of the protective film-attached polarizing plate 7 opposite to the side on which the protective film 1 is laminated. It is a process of laminating. 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 long.
The length of the long optical laminate is, for example, 100 to 20000 m, preferably 1000 to 10000 m. The width of the elongated optical laminate is, for example, 0.5 to 3 m, and preferably 1 to 2.5 m.

The lamination of the retardation layer on the protective film-attached polarizing plate 7 can include the step of peeling the substrate film after laminating the laminate including the substrate film and the retardation layer on the opposite side. This method is advantageous when the retardation layer is a layer formed by coating (coating) such as a liquid crystal curing retardation layer.
In the case where the step of laminating the retardation layer includes the step of peeling the base film, reverse curl tends to occur in the obtained optical laminate, but according to the present invention, the step of peeling the base film is included. Even if it is, it is possible to manufacture an optical laminate in which reverse curl is suppressed.

For example, as a method of laminating the first retardation layer 3 which is a layer formed by coating on the protective film-attached polarizing plate 7, a method including the following steps may be mentioned. The second retardation layer 4 can also be laminated in the same manner.
[A] forming an alignment layer on a substrate film,
[B] forming a first retardation layer 3 on the alignment layer to obtain a laminate,
[C] a step of laminating the laminate on the protective film-attached polarizing plate 7 via the first adhesive layer 3a, and [d] a step of peeling the base film.

  The alignment layer is not particularly limited as long as it can impart an alignment property such as horizontal alignment, vertical alignment, hybrid alignment, or tilt alignment to the liquid crystal compound contained in the retardation layer. Examples of the alignment layer include an alignment film made of an alignment polymer, a photo alignment film using a photo alignment polymer, or a groove alignment film, etc. A photo alignment using a photo alignment polymer Preferably it is a membrane.

When the alignment layer is an alignment film formed of an alignment polymer, the alignment regulating force with respect to the liquid crystal compound can be arbitrarily adjusted depending on the surface state and the rubbing conditions. In this case, a composition containing an orientation polymer and a solvent is applied to a substrate film to remove the solvent, or the composition is applied to a substrate film to remove the solvent, and then a known rubbing treatment is performed. To form an alignment layer.
When the alignment layer is a photoalignment film using a photoalignment polymer, a composition containing a polymer or monomer having a photoreactive group and a solvent is applied to a substrate film to remove the solvent and then irradiated with polarized light. By doing this, an alignment layer can be obtained. As 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 the alignment layer to remove the solvent, and then irradiating the ultraviolet light to meet the alignment control force of the alignment layer. The liquid crystal compound can be formed by being aligned in an alignment state.
As the liquid crystal compound, 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 alignment direction of the liquid crystal compound contained in the retardation layer may be regulated using the alignment layer as described above, but in the case of using a polymerizable liquid crystal compound as the liquid crystal compound, polymerization is performed by irradiating polarized light. It can also be adjusted by photo-orienting the liquid crystal compound to express or improve the orientation of the polymerizable liquid crystal compound.

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

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

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

(3) Third Step When the optical laminate obtained in the second step is long, it is preferable to cut out the sheet from the long optical laminate by this step.
Cutting (cutting) can be performed using a conventionally known cutting means such as a cutting cutter.
The description of <optical laminated body> (1) is cited for the size, shape and cutting angle of the sheet.

  Hereinafter, the present invention will be more specifically described by way of examples, but the present invention is not limited by these examples.

  In the following examples, the thicknesses of the polarizing plate and the film, the difference in elastic modulus of the protect film, and the tension before bonding in the MD direction of the polarizing plate and the protect film were measured according to the following.

(1) Thickness of Polarizing Plate and Film The thickness was measured using a digital micrometer “MH-15M” manufactured by Nikon Corporation.

(2) Elastic modulus difference of protect film The above-mentioned sample for elastic modulus measurement is the above-mentioned so that the interval of a grasping tool becomes 5 cm with the upper and lower grips of a tensile tester [Autograph AG-Xplus testing machine made by Shimadzu Corporation]. The measurement sample is pulled in the longitudinal direction of the measurement sample at a tensile speed of 1 mm / min in an environment of 23 ° C. and a relative humidity of 55% by sandwiching both ends in the long side direction of the measurement sample. The tensile elastic modulus [MPa] at 23 ° C. and 55% relative humidity was calculated from the slope of the line between ̃6 MPa. At this time, a thickness value of only biaxially stretched polyethylene terephthalate (base film) was used as a thickness for calculating stress.
The tensile elastic modulus calculated from the measurement of the first elastic modulus measurement sample is the first elastic modulus, and the tensile elastic modulus calculated from the measurement of the second elastic modulus sample is the second elastic modulus.

The first elastic modulus-the second elastic modulus was calculated from the obtained first elastic modulus and the second elastic modulus.
Hereinafter, the first elastic modulus-the second elastic modulus is simply referred to as "elastic modulus difference".

(3) Tension before bonding in the MD direction of the polarizing plate and the protective film A pair of bonding rolls for bonding the polarizing plate and the protective film, and a pair of nip rolls upstream of and closest to the bonding roll Measuring the film tension [N / m] of the polarizing plate and the protective film traveling between and using a tension detection roll disposed between the bonding roll and the pair of nip rolls closest to the bonding roll, The tension before bonding in the MD direction.

<Examples 1 to 3, Comparative Examples 1 to 2>
(A) Preparation of Polarizer While continuously conveying a long polyvinyl alcohol film [average degree of polymerization: about 2400, degree of saponification: 99.9 mol% or more, thickness: 30 μm], it is about 4 times dry Uniaxially stretched and then dipped in pure water at 40 ° C. for 1 minute while maintaining tension, and then at a temperature of 28 ° C. for 60 seconds in an aqueous solution with an iodine / potassium iodide / water ratio of 0.1 / 5/100. Soaked. Thereafter, it was immersed in an aqueous solution of potassium iodide / boric acid / water at a weight ratio of 10.5 / 7.5 / 100 at 68 ° C. for 300 seconds. Subsequently, the film was washed with pure water at 5 ° C. for 5 seconds, and then dried at 70 ° C. for 180 seconds to obtain a long polarizer in which iodine was adsorbed and oriented to a uniaxially stretched polyvinyl alcohol film. The thickness of the polarizer was 13 μm.

(B) Preparation of Polarizing Plate The elongated polarizer obtained in the above (A) is continuously transported, and the elongated first thermoplastic resin film [Clear Hard Coat manufactured by Nippon Paper Industries Co., Ltd.] A trade name “COP 25 ST-HC” which is a film, a film in which a clear hard coat layer is formed on a cyclic polyolefin resin film, a thickness of 29 μm] and a long second thermoplastic resin film [Fuji Film Co., Ltd.] Trade name "ZRG20SL" which is a manufactured triacetyl cellulose (TAC) film, thickness: 20 μm] is continuously conveyed, and between the polarizer and the first thermoplastic resin film, and the polarizer and the second thermoplastic resin The first thermoplastic resin film / water-based adhesive layer / polarizer / water-based adhesive layer / second heat-permeable material is passed between a pair of bonding rolls while injecting a water-based adhesive between the film and the film. To obtain a laminated film composed of a sexual resin film.
Subsequently, the obtained laminated film was conveyed, and was subjected to heat treatment at 80 ° C. for 300 seconds by passing it through a hot air drier to dry the water-based adhesive layer, thereby obtaining a long polarizing plate.
The aqueous adhesive described above has a concentration 3 obtained by dissolving polyvinyl alcohol powder (trade name "Gausefir" manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average degree of polymerization: 1100) in hot water at 95 ° C. An aqueous solution was used in which 1 wt. Part of a crosslinker [sodium glyoxylate manufactured by Japan Synthetic Chemical Industry Co., Ltd.] was mixed with 10 wt. Parts of polyvinyl alcohol powder in a polyvinyl alcohol aqueous solution at a weight%. The thickness of the obtained polarizing plate was 62 μm.

(C) Preparation of polarizing plate with long protective film While continuously conveying the long polarizing plate obtained in the above (B), a long protective film from which a separate film is peeled off [biaxial film Continuously conveys “AY-4212” manufactured by Fujimori Kogyo Co., Ltd., in which a (meth) acrylic pressure-sensitive adhesive layer (thickness: 15 μm) is laminated on stretched polyethylene terephthalate (thickness: 38 μm) These were stacked and passed between a pair of bonding rolls to press the laminate of the protective film and the polarizing plate from above and below, thereby continuously manufacturing a polarizing plate with a long protective film.
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.
In addition, the pressure (nip pressure) given to the laminated body of a protection film and a polarizing plate by the bonding roll was 0.1 Mpa. At this time, the tension before bonding in the MD direction of the polarizing plate was 151 N / m, and the tension before bonding in the MD direction of the protect film was 327 N / m.

  The manufacturing method of the polarizing plate with a long protective film in Examples 1 to 3 and Comparative Examples 1 and 2 is the same except that the used protective film is different (the product is the same but the lot is different). .

(D) Preparation of a long optical laminate A (meth) acrylic pressure-sensitive adhesive layer with a thickness of 5 μm is provided on the surface of the polarizing plate of the protective film-attached polarizing plate obtained in (C) above on the side opposite to the protective film. A separate film consisting of a 2 μm thick liquid crystal curable retardation layer / 5 μm thick (meth) acrylic adhesive layer / 1 μm thick liquid crystal curable retardation layer / 25 μm thick (meth) acrylic adhesive layer / polyethylene terephthalate film The films were laminated in this order to prepare a long optical laminate.
The laminate of the liquid crystal curing type retardation layer having a thickness of 2 μm is obtained by forming an alignment layer and a liquid crystal curing type retardation layer on a base film made of triacetyl cellulose (TAC) film, It was bonded to the surface on the opposite side through the acrylic pressure-sensitive adhesive layer, and then peeling off the alignment layer and the base film.
Similarly, after lamination of a liquid crystal curing type retardation layer having a thickness of 1 μm, an orientation layer and a liquid crystal curing type retardation layer are formed on a base film made of a triacetyl cellulose (TAC) film, It was bonded to the surface of a 2 [mu] m-thick liquid crystal-curable retardation layer via a (meth) acrylic pressure-sensitive adhesive layer, and then peeling off the alignment layer and the base film.
Thereafter, a laminate of a 25 μm thick (meth) acrylic pressure-sensitive adhesive layer and a separate film consisting of a polyethylene terephthalate film is bonded to the surface of a 1 μm thick liquid crystal curable retardation layer to obtain a long optical laminate. Made.
The thickness of the obtained long optical laminate (excluding the separate film) was 100 μm.

(E) Measurement of Elastic Modulus Difference of Protecting Film From the central part in the width direction of the obtained long optical laminate, rectangular pieces of 100 mm long by 25 mm short sides were cut using a supercutter. The cutting was performed such that the long side of the small piece was parallel to the TD direction of the long optical laminate, and the short side of the small piece was parallel to the MD direction of the long optical laminate. The protective film was peeled off from the small piece and taken out as a sample for measurement of the first elastic modulus.
Similarly, rectangular pieces with a long side of 100 mm and a short side of 25 mm were cut out from the long optical laminate using a supercutter. However, the cutting was performed so that the long side of the small piece was parallel to the MD direction of the long optical laminate, and the short side of the small piece was parallel to the TD direction of the long optical laminate. In addition, the position at which the small piece was cut out was set so that the position in the width direction of the elongated optical laminate was the same as the measurement sample of the first elastic modulus. The protective film was peeled off from the small piece and taken out as a sample for measurement of the second elastic modulus.
The first elastic modulus and the second elastic modulus of the long protective film are the same regardless of the cut-out position in the length direction, as long as the cut-out position in the width direction is the same.
The first elastic modulus, the second elastic modulus, and the elastic modulus difference were determined according to the method described above for the first elastic modulus measurement sample and the second elastic modulus measurement sample. The results are shown in Table 1.

(F) Preparation of Sheet of Optical Laminate As shown in FIG. 6, the absorption axis 61 of the polarizing plate when viewed from the protective film side from the long optical laminate 60 obtained in (D). Sheet (70 mm long) of a rectangular shape (long side 140 mm × short side 70 mm) was cut out using a supercutter so that the length 45 degrees with respect to the long side and the short side, to obtain an optical laminated sheet . The sheet 70 was cut out from the center in the width direction. The first elastic modulus and the second elastic modulus of the protect film of the sheet 70 are measured by cutting out the measurement sample from the elongated optical laminate according to the above, and the second elastic modulus and the second elastic modulus, respectively. It is the same value as the elastic modulus.

(G) Measurement of MD Curl Amount of Sheet of Optical Laminate With respect to the sheet 70 of the obtained optical laminate, the amount of MD curl was measured according to the following method. The results are shown in Table 1. The cutting of the sheet 70 was performed under an environment of 23 ° C. and a relative humidity of 55% immediately after producing the long optical laminate.
The sheet 70 was placed on the reference surface (horizontal stand) with the concave side up. In this state, of the two diagonal lines of sheet 70, the height from the reference plane is measured for each of two corners 80 on the smaller diagonal line of the sheet 70 with respect to the absorption axis direction of the polarizing plate. The MD curling amount [mm] was determined as the average of the heights of the two corners 80.
A state in which the protective film side is concave is a state in which the positive curl is provided, and a state in which the protective film side is convex is the state in which the reverse curl is provided.
In Table 1, when the value of the MD curl amount is a positive value, it indicates that it is a positive curl, and when it is a negative value, it indicates that it is a reverse curl. That the MD curl amount is 0 mm means that the two corners 80 did not rise even when the protective film side of the sheet 70 is up and the opposite side is up.

  Reverse curl was suppressed and the sheet of the optical laminated body of Examples 1-3 provided with the protect film which satisfy | fills Formula (I) had a flat state. After peeling and removing the separate film from the sheet of each of Examples 1 to 3, the MD curling amount was measured by the same method as the above (G).

  Reference Signs List 1 protect 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-sensitive adhesive layer, 6 separate film, 7 Protecting film-attached polarizing plate, 8 bonding roll, 10 polarizer, 20 first thermoplastic resin film, 30 second thermoplastic resin film, 40 base film, 50 second pressure-sensitive adhesive layer, 60 long optical laminate , 61 absorption axis of the polarizing plate, 70 sheet, 80 sheet corner.

Claims (5)

A protective film, a polarizing plate, one or more retardation layers, and an adhesive layer in this order,
The optical laminated body in which the said protective film satisfy | fills following formula (I).
1st elastic modulus-2nd elastic modulus 300 300MPa (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 ° C. and a relative humidity of 55% RH, and a second elastic modulus is a temperature of 23 ° C., It is a tensile elastic modulus in a direction parallel to the absorption axis of the polarizing plate at a relative humidity of 55% RH. ]   The optical laminate according to claim 1, wherein a thickness of the polarizing plate is 110 μm or less.   The optical laminate according to claim 1, wherein the one or more retardation layers include a retardation layer composed of a cured product of a liquid crystal compound. It is a method of manufacturing an optical layered product according to any one of claims 1 to 3,
A first step of laminating a protective film including 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 the side opposite to the one side of the polarizing plate;
A third step of cutting the optical laminate from the region;
A manufacturing method of the above-mentioned optical layered product containing.
1st elastic modulus-2nd elastic modulus 300 300MPa (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 ° C. and a relative humidity of 55% RH, and a second elastic modulus is a temperature of 23 ° C., It is a tensile elastic modulus in a direction parallel to the absorption axis of the polarizing plate at a relative humidity of 55% RH. ]   The method according to claim 4, wherein the second step includes the step of peeling the base film after laminating a laminate including the base film and the retardation layer on the opposite side.

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