TW201936407A - Method for producing polarizing plate sheet with protective film - Google Patents

Abstract

Provided is a method for producing a polarizing plate sheet with protective film, containing a step of obtaining a polarizing plate with protective film by laminating a protective film containing a region satisfying the formula: TD elastic modulus-MD elastic modulus ≥ 300 MPa on one side of a polarizing plate, and a step of cutting out a sheet of the polarizing plate with protective film from the aforesaid region. In the formula, the TD elastic modulus is the tensile elastic modulus in the TD direction at a temperature of 23 DEG C and a relative humidity of 55% RH, and MD elastic modulus is the tensile modulus in the MD direction at a temperature of 23 DEG C and a relative humidity of 55% RH.

Description

Method for producing polarizing plate sheet with protective film

The present invention relates to a method of producing a polarizing plate sheet having a protective film. Further, the present invention also relates to a polarizing plate sheet having a protective film and a long polarizing plate with a protective film attached thereto.

In recent years, image display devices such as liquid crystal display devices and organic EL display devices, such as smart phone-like portable terminals, have been rapidly developed in terms of design and portability in terms of large screens and simplifications. In order to achieve long-term driving with a limited thickness, it is also desired to use high polarizing and thin weight for the polarizing plate to be used.

Conventionally, a polarizing plate is generally used in a polarizing film made of a polyvinyl alcohol-based resin, and a protective film made of cellulose triacetate (TAC) is bonded by an adhesive. However, in recent years, a protective film made of a resin other than TAC has been used from the viewpoints of film formation, durability, cost, productivity, and the like (for example, JP-A-2004-245925 (Patent Document 1) )].

With the demand for thinning of the polarizing plate, the thinning of the polarizer and the protective film is progressing. The sheet-like body of the polarizing plate which can be obtained by cutting out from a thin and inelastic polarizing plate (especially a long polarizing plate) is liable to cause bow-shaped reverse bending deformation. In this specification, this deformation is also referred to as "curl".

In general, a polarizing plate that is distributed in the market is a polarizing plate with a protective film attached thereto, and a peelable protective film (also referred to as a surface protective film) for protection is attached to the surface. In the case of a polarizing plate with a protective film, if it is made into a sheet-like body, it tends to be curled.

The curl of the polarizing plate sheet with the protective film has two types of "positive curl" and "reverse curl". In the polarizing plate sheet body including the protective film of the "layered body of the polarizing plate and the protective film", "positive curling" means that the surface on the side of the polarizing plate has a convex shape, and "reverse curling" means a protective film. The side faces show a convex curl.

When the reverse curl is generated, when the polarizing plate side of the polarizing plate-like sheet having the protective film is bonded to the image display element such as the liquid crystal cell or the organic EL element via the adhesive layer, the bonding error is likely to occur. Or the problem of air bubbles mixed in the interface between the adhesive layer and the image display element.

The polarizing plate with a protective film is a further multilayer structure by laminating another one or more optical functional layers or the like via an adhesive layer or an adhesive layer on the side of the polarizing plate. At this time, when the polarizing plate with the protective film is further added with a layer, the multilayered structure is deformed in the reverse crimping direction.

Therefore, in consideration of the above-described multilayer structure, the polarizing plate sheet with the protective film preferably has a sufficiently large positive curl. In this case, when the multilayered structure has reverse curl, it is likely to cause the above-mentioned problem when it is bonded to the image display element.

On the other hand, when the polarizing plate with the protective film is not directly bonded to the image display element, the large positive curl does not hinder the bonding to the image display element.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a "polarizing plate sheet with a protective film" having a large positive curl.

Another object of the present invention is to provide a "polarizing plate sheet body with a protective film" which can have a large positive curl.

Still another object of the present invention is to provide a long-length polarizing plate with a protective film which can impart a "polarizing plate sheet with a protective film" having a large positive curl.

The present invention provides a method for producing a polarizing plate sheet having a protective film as described below, a polarizing plate sheet having a protective film, and a long polarizing plate with a protective film.

[1] A method for producing a polarizing plate sheet having a protective film, comprising the steps of: bonding a protective film comprising a region satisfying the following formula (I) to a single side of a polarizing plate, and obtaining the attached a step of protecting the polarizing plate of the film; and a step of cutting out the sheet-like body of the polarizing plate with the protective film from the aforementioned region; TD elastic modulus-MD elastic modulus ≧300 MPa (I)

In the formula, the TD elastic modulus refers to the tensile elastic modulus in the TD direction at a temperature of 23 ° C and a relative humidity of 55% RH, and the MD elastic modulus refers to a temperature of 23 ° C and a relative humidity of 55% RH. Tensile modulus of elasticity in the MD direction.

[2] The production method according to [1], wherein the polarizing plate and the protective film are sandwiched between a pair of rolls and bonded together.

[3] The production method according to [2], wherein the polarizing plate has a long shape, and the protective film has a long shape.

[4] The production method according to the above [3], wherein the pre-bonding tension of the polarizing plate is 200 N/m or less, and the pre-bonding tension of the protective film is 300 N/m or more.

[5] The production method according to any one of [1] to [4] wherein the absorption axis of the polarizing plate is bonded to the MD direction of the protective film in parallel.

[6] The production method according to any one of [1] to [5] wherein the polarizing plate has a thickness of 70 μm or less.

[7] A polarizing plate sheet having a protective film, comprising: a polarizing plate; and a protective film laminated on one side thereof; wherein the protective film satisfies the following formula (II), the first elastic modulus - 2nd elastic modulus ≧300MPa (II)

In the formula, the first elastic modulus refers to a tensile elastic modulus in a direction orthogonal to the absorption axis of the polarizing plate at a temperature of 23 ° C and a relative humidity of 55% RH, and the second elastic modulus means The tensile elastic modulus in a direction parallel to the absorption axis of the polarizing plate at a temperature of 23 ° C and a relative humidity of 55% RH.

[8] The polarizing plate sheet body with a protective film as described in [7], wherein the surface of the polarizing plate side is convex, and the amount of curling in a direction parallel to the absorption axis of the polarizing plate is 40mm or more.

[9] The polarizing plate sheet having a protective film according to [7] or [8], wherein the polarizing plate has a thickness of 70 μm or less.

[10] A long strip-shaped polarizing plate with a protective film, comprising: a strip-shaped polarizing plate; and a long protective film laminated on one side thereof; wherein the protective film comprises the following formula In the region of (III), the first elastic modulus - the second elastic modulus ≧ 300 MPa (III), the first elastic modulus refers to the long strip shape at a temperature of 23 ° C and a relative humidity of 55% RH. The absorption axis of the polarizing plate has a tensile elastic modulus in the orthogonal direction, and the second elastic modulus refers to the absorption axis of the long polarizing plate at a temperature of 23 ° C and a relative humidity of 55% RH. The tensile modulus of elasticity in the direction parallel.

[11] The long polarizing plate with a protective film according to [10], wherein the region spans the entire width direction of the protective film.

According to the present invention, it is possible to provide a method of manufacturing a "polarizing plate sheet with a protective film" having a large positive curl.

According to the present invention, it is possible to provide a "polarizing plate sheet body with a protective film" which can have a large positive curl.

According to the present invention, it is possible to provide a long-length polarizing plate with a protective film which can impart a "polarizing plate sheet with a protective film" having a large positive curl.

1‧‧‧Protective film

2, 2a, 2b‧‧‧ polarizing plate

3‧‧‧Polarizer with protective film

5‧‧‧Fitting roller

10‧‧‧ polarizer

20‧‧‧1st thermoplastic resin film

30‧‧‧2nd thermoplastic resin film

40‧‧‧Base film

50‧‧‧Adhesive layer

60‧‧‧Long strip of polarizing plate with protective film

61‧‧‧Absorption axis of polarizing plate

70‧‧‧Determination of MD curl amount

80‧‧‧The corner of the sample for measurement

Fig. 1 is a flow chart showing a method of manufacturing a polarizing plate sheet with a protective film.

Fig. 2 is a schematic cross-sectional view showing an example of a layer configuration of a polarizing plate.

Fig. 3 is a schematic cross-sectional view showing another example of the layer configuration of the polarizing plate.

Fig. 4 is a side view showing an example of a bonding step S101 of bonding a polarizing plate and a protective film.

Fig. 5 is a schematic cross-sectional view showing an example of a configuration of a sheet of a polarizing plate with a protective film.

Fig. 6 is a schematic view showing a method of preparing a sample for measuring the amount of MD crimp and a measurement point of the MD curl amount.

Fig. 7 is a graph showing the relationship between "the position in the width direction of the respective protective films 1 to 3" and the "modulus of the elastic modulus" in Experimental Examples 1 to 3.

Fig. 8 is a view showing the position in the width direction of the polarizing plate sheet with the protective film cut from the long strip-shaped polarizing plate with the protective film in the experimental examples 1 to 3 and the protection of the cut-out A graph showing the relationship between the amount of MD curl of the sheet-shaped polarizing plate sheet.

<Method for Producing Polarizing Plate Sheet Body with Protective Film>

Referring to Fig. 1, a method for producing a polarizing plate-like sheet with a protective film according to the present invention includes the following step: a bonding step S101 of attaching a protective film to one side of a polarizing plate to provide protection a polarizing plate of the film; and a cutting step S102, which cuts out the sheet-like body of the polarizing plate with the protective film.

Hereinafter, each step will be described in detail.

In the present specification, "sheet-like body" means a film of a smaller size cut out from a film of a larger size (for example, a strip-shaped film).

(1) Fitting step S101

(1-1) Polarizing plate for bonding step S101

(1-1-1) Composition of polarizing plate

The polarizing plate is a polarizing element including at least a polarizing plate, and usually further comprises a thermoplastic resin film attached to one or both sides thereof.

The thermoplastic resin film may be a protective film that protects the polarizer, another optical film that has different optical functions from the polarizer, and the like. Examples of other optical films include a retardation film, a brightness enhancement film, and the like.

The thermoplastic resin film may have 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 antireflection layer, an antistatic layer, an antifouling layer, and the like.

The thermoplastic resin film can be bonded to the polarizer via an adhesive layer or an adhesive layer.

The thickness of the polarizing plate is usually 150 μm or less, and is preferably 100 μm or less from the viewpoint of film formation of the polarizing plate and easy production of a polarizing plate sheet having a protective film sufficiently large in curling. 80 μm or less, and more preferably 70 μm or less.

The thickness of the polarizing plate is usually 20 μm or more or 30 μm or more.

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

The polarizing plate 2a shown in FIG. 2 includes a polarizing plate 10, a first thermoplastic resin film 20 bonded to one surface of the polarizing film 10, and a second thermoplastic resin film 30 bonded to the other surface of the polarizing film 10. The first and second thermoplastic resin films 20 and 30 are, for example, protective films.

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

In the second and third figures, although not shown, it is preferable to bond the polarizer 10 and the first and second thermoplastic resin films 20 and 30 using an adhesive.

The polarizing plate for bonding to step S101 is preferably elongated.

The length of the strip-shaped polarizing plate to be applied to the bonding step S101 is, for example, 100 to 20,000 m, preferably 1,000 to 10,000 m. Further, the width of the long polarizing plate to be applied to the bonding step S101 is, for example, 0.5 to 3 m, preferably 1 to 2.5 m.

(1-1-2) Polarizer

The polarizer 10 constituting the polarizing plate is an absorbing polarizer having a linear polarized light that absorbs a vibrating surface that is parallel to its absorption axis, and is transmissive and orthogonal to the absorption axis (parallel to the transmission axis). The nature of the linear polarization of the vibrating surface. One example of the polarizer 10 is a polarizer obtained by adsorbing a dichroic dye to a polyvinyl alcohol-based resin film which is stretched by one axis. Such a polarizing plate 10 can be produced, for example, by a method comprising the steps of: stretching a polyvinyl alcohol-based resin film by one axis; and dyeing the polyvinyl alcohol-based resin film by a dichroic dye to adsorb it a step of treating a coloring dye; a step of treating the polyvinyl alcohol-based resin film which adsorbs the dichroic dye with a crosslinking liquid such as a boric acid aqueous solution; and a step of performing water washing after the crosslinking liquid treatment.

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

In the present specification, "(meth)acrylic acid" means at least one selected from the group consisting of acrylic acid and methacrylic acid. The same applies to "(meth)acrylonitrile" and "(meth)acrylate".

The degree of saponification of the polyvinyl alcohol-based resin is usually from 85 to 100 mol%, preferably from 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, poly(vinyl formal) or poly(vinyl acetal) modified with an aldehyde may be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually from 1,000 to 10,000, preferably from 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.

The film obtained from such a polyvinyl alcohol-based resin is used as a raw material film of the polarizer 10. The method of forming a film of a polyvinyl alcohol-based resin is not particularly limited, and a known method can be employed. The thickness of the polyvinyl alcohol-based resin film is not particularly limited, and is, for example, about 10 to 150 μm, preferably 50 μm or less, and more preferably 35 μm or less.

One of the stretching of the polyvinyl alcohol-based resin film can be carried out before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing. When the one-axis extension is performed after dyeing, the one-axis extension can be performed before the crosslinking treatment or in the crosslinking treatment. Moreover, one-axis extension can also be performed in the plurality of stages.

When extending in one axis, it may be extended on one axis between rolls having different peripheral speeds, or may be extended on one axis using a heat roll. Further, the one-axis extension may be a dry stretching in which the stretching is performed in the air, or may be a wet stretching in which the polyvinyl alcohol-based resin film is swollen using a solvent or water. The stretching ratio is usually 3 to 8 times.

A method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye is, for example, a method of immersing the film in an aqueous solution containing a dichroic dye. Dichromatic pigments can use iodine or Dichromatic organic dyes. Moreover, it is preferable that the polyvinyl alcohol-based resin film is subjected to water immersion treatment before the dyeing treatment.

In the cross-linking treatment after dyeing with a dichroic dye, a method of immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid is usually employed. When iodine is used as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide.

The thickness of the polarizer 10 is usually about 2 to 40 μm. The thickness of the polarizer 10 is preferably 20 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less from the viewpoint of film formation of the polarizing plate.

On the other hand, from the viewpoint of easily producing a polarizing plate sheet having a protective film sufficiently large in curling, it is preferable that the thickness of the polarizing plate 10 is large, and specifically, preferably 10 μm or more, more preferably It is 15 μm or more, and more preferably 20 μm or more.

(1-1-3) First and second thermoplastic resin films

Each of the first and second thermoplastic resin films 20 and 30 is independently a film made of a translucent thermoplastic resin (preferably an optically transparent thermoplastic resin). The thermoplastic resin constituting the first and second thermoplastic resin films 20 and 30 may be, for example, a chain-like polyolefin resin (such as a polypropylene resin) or a cyclic polyolefin resin (such as a decene-based resin). Olefin resin; cellulose resin such as cellulose triacetate or cellulose diacetate; polyester resin such as polyethylene terephthalate or polybutylene terephthalate; polycarbonate resin; methyl group (meth)acrylic resin such as acrylic acid methyl resin; polystyrene resin; polyvinyl chloride resin; acrylonitrile/butadiene/styrene resin; acrylonitrile/styrene resin; polyvinyl acetate Resin; polyvinylidene chloride resin; polyamine resin; polyacetal resin; modified polyphenyl ether resin; polyfluorene tree Fat; polyether oxime resin; polyaryl lipid resin; polyamidoximine resin; polyamidene resin.

The chain-like polyolefin resin may, for example, be a homopolymer of a chain olefin such as a polyethylene resin or a polypropylene resin, and may be a copolymer composed of two or more kinds of chain olefins. More specific examples include a polypropylene resin (a polypropylene resin as a homopolymer of propylene, a copolymer mainly composed of propylene), a polyethylene resin (a polyethylene resin as a homopolymer of ethylene, and ethylene). Copolymer for the main body).

The cyclic polyolefin resin is a general term for a resin obtained by polymerizing a cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin-based resin include a ring-opening (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a cyclic olefin, and a chain olefin such as ethylene or propylene. Copolymers (which are representative of random copolymers), and graft polymers which have been modified with unsaturated carboxylic acids or derivatives thereof, and such hydrides and the like. Among them, a norbornene-based resin using a norbornene-based monomer such as a norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is suitable.

The cellulose resin refers to one or all of the hydrogen atoms in the hydroxyl group of the cellulose obtained from the raw material cellulose such as cotton linter or wood pulp (broadwood pulp, softwood pulp). A cellulose organic acid ester or a cellulose mixed organic acid ester obtained by substituting a mercapto group, a propyl group and/or a butyl group. For example, it is composed of cellulose acetate, propionate, butyrate, and a mixed ester thereof. Among them, cellulose triacetate, cellulose diacetate, cellulose acetate propionate, and cellulose acetate butyrate are preferred.

The polyester-based resin is a resin other than the above-described cellulose-based resin having an ester bond, and generally contains a polycondensate composed of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. Polycarboxylic acid or its derivative As the organism, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalate. As the polyol, a divalent diol can be used, and examples thereof include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexane dimethanol. An example of a suitable polyester resin is polyethylene terephthalate.

The polycarbonate resin is an engineering plastic containing "a polymer obtained by bonding a monomer unit via a carbonate group", and is a resin having high punching resistance, heat resistance, flame retardancy, and transparency. The polycarbonate resin may be a resin called a modified polycarbonate obtained by modifying a polymer skeleton to reduce a photoelastic coefficient, or a copolymerized polycarbonate having improved wavelength dependence.

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

The methacrylate which can constitute a (meth)acrylic resin is preferably an alkyl methacrylate. The alkyl methacrylate may, for example, be methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, or An alkyl methacrylate having an alkyl carbon number of 1 to 8 such as a third butyl acrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate or 2-hydroxyethyl methacrylate. The alkyl methacrylate preferably has an alkyl carbon number of from 1 to 4. In the (meth)acrylic resin, the methacrylate may be used alone or in combination of two or more.

Examples of the other polymerizable monomer which can constitute the (meth)acrylic resin include acrylates and other compounds having a polymerizable carbon-carbon double bond in the molecule. The other polymerizable monomers may be used alone or in combination of two or more. The acrylate is preferably an alkyl acrylate. The alkyl acrylate may, for example, be methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, acrylic acid. An alkyl acrylate having an alkyl group having 1 to 8 carbon atoms such as cyclohexyl ester or 2-hydroxyethyl acrylate. The alkyl acrylate preferably has an alkyl carbon number of from 1 to 4. In the (meth)acrylic resin, the acrylate may be used alone or in combination of two or more.

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

The first and second thermoplastic resin films 20 and 30 may be a protective film for laminating the polarizer 10 on the side of the polarizer 10 . The first or second thermoplastic resin films 20 and 30 may have a protective film of an optical function such as a retardation film and a brightness enhancement film.

For example, a thermoplastic resin film composed of the above materials is stretched (one-axis extension or biaxial stretching or the like), or a liquid crystal layer or the like is formed on the film, whereby a retardation film imparted with an arbitrary retardation value can be produced. . 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, or an antifouling layer laminated on the surface thereof.

The thickness of the first and second thermoplastic resin films 20 and 30 is usually from 1 to 100 μm, but is preferably from 5 to 60 μm, more preferably from 5 to 50 μm from the viewpoint of strength, workability and the like.

It is preferable that the thickness of the first thermoplastic resin film 20 and the second thermoplastic resin film 30 is small from the viewpoint of easily producing a polarizing plate sheet having a protective film which is sufficiently thick, and particularly preferably. It is 40 μm or less, more preferably 30 μm or less.

When the polarizing plate 2a shown in Fig. 2 is provided with a thermoplastic resin film on both surfaces of the polarizer 10, the thermoplastic resin film may be composed of the same type of thermoplastic resin, or may be composed of different types of thermoplastic resins. Also, the thickness may be the same or different. Furthermore, it may have the same phase difference characteristics and may have different phase difference characteristics. When the composition of the thermoplastic resin film bonded to both sides is different, the polarizing plate sheet with the protective film is particularly likely to be curled, which is particularly advantageous in the present invention.

(1-1-4) Adhesive

As described above, the first and second thermoplastic resin films 20 and 30 can be bonded to the polarizer 10, for example, via an adhesive layer. As the 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 or an active energy ray-curable adhesive is preferable.

Examples of the aqueous binder include an adhesive composed of a polyvinyl alcohol resin aqueous solution, and an aqueous two-component urethane emulsion adhesive. Among them, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is suitably used. In the case of the polyvinyl alcohol-based resin, in addition to the vinyl alcohol homopolymer obtained by subjecting polyvinyl acetate as a homopolymer of vinyl acetate to saponification, it is also possible to copolymerize with vinyl acetate. The polyvinyl alcohol-based copolymer obtained by the saponification treatment of the copolymer formed by the other monomer, or the hydroxyl groups thereof are partially modified A modified polyvinyl alcohol polymer or the like. The aqueous binder may include a crosslinking agent such as an aldehyde compound (glyoxal or the like), an epoxy compound, a melamine-based compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

When a water-based adhesive is used, it is preferred to carry out a drying step for removing water contained in the water-based adhesive after bonding the polarizer 10 to the first and second thermoplastic resin films 20 and 30. After the drying step, a ripening step such as aging at a temperature of 20 to 45 ° C may be provided.

The active energy ray-curable adhesive refers to an adhesive containing a curable compound which is cured by irradiation with an active energy ray such as ultraviolet light, visible light, electron beam or X-ray, and is preferably an ultraviolet 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 an epoxy compound (a compound having one or two or more epoxy groups in the molecule) and an oxetane compound (one or two in the molecule). a compound of the above oxetane ring), or a combination thereof. The radically polymerizable curable compound is, for example, a (meth)acrylic resin compound (a compound having one or two or more (meth)acryl decyloxy groups in the molecule), and has radical polymerizability. Other vinyl compounds of double bonds, or combinations of these. A cationically polymerizable curable compound and a radically polymerizable curable compound can 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 a hardening reaction of the curable compound.

When the polarizer 10 and the first and second thermoplastic resin films 20 and 30 are bonded, in order to improve the adhesion, the bonding surface of at least one of these may be subjected to a surface activation treatment. The surface activation treatment may be, for example, corona treatment, plasma treatment, discharge treatment (glow discharge treatment) Dry processing such as flame treatment, ozone treatment, UV ozone treatment, ionization active line treatment (ultraviolet treatment, electron beam treatment, etc.); ultrasonic treatment using a solvent such as water or acetone, saponification treatment, anchor coating treatment Wet treatment. These surface activation treatments may be carried out singly or in combination of two or more.

When the thermoplastic resin film is bonded to both surfaces of the polarizer 10, the adhesive for bonding the thermoplastic resin films may be the same type of adhesive, or may be a different type of adhesive.

(1-2) Protective film for bonding step S101

(1-2-1) Composition of protective film

The protective film is used to protect the film on the surface of the polarizing plate. Usually, for example, after the polarizing plate sheet having the protective film is attached to the image display element or the like, when the adhesive layer is provided, the adhesive layer is peeled off one by one. Therefore, the protective film 1 is attached to the above surface of the polarizing plate 2 in a peelable manner.

The protective film can be composed, for example, of a base film and an adhesive layer laminated thereon.

The base material film may be a thermoplastic resin (for example, a polyolefin resin such as a polyethylene resin, a polypropylene resin, or a cyclic polyolefin resin; a polyester system such as polyethylene terephthalate or polyethylene naphthalate; Resin; polycarbonate resin; (meth)acrylic resin, etc.). The base film may have a single layer structure or a multilayer structure.

The adhesive layer may be composed of a (meth)acrylic resin adhesive, an epoxy adhesive, an amine ester adhesive, a silicone adhesive, or the like.

Further, the protective film may be a self-adhesive resin film such as a polypropylene resin or a polyethylene resin. At this time, the protective film does not have an adhesive layer.

The thickness of the protective film may be, for example, 5 to 150 μm, preferably 10 to 100 μm, more preferably 20 to 75 μm, still more preferably 25 to 70 μm (for example, 60 μm or less, preferably 55 μm or less). When the thickness of the protective film is less than 5 μm, the protection of the polarizing plate may become insufficient, and it is also disadvantageous in terms of operability. When the thickness of the protective film is more than 150 μm, it is disadvantageous in terms of film formation of the polarizing plate sheet with the protective film and reworkability of the protective film.

The protective film to be applied to the bonding step S101 is preferably elongated.

The length of the long protective film to be applied to the bonding step S101 is, for example, 100 to 20,000 m, preferably 1,000 to 10,000 m. Further, the width of the long protective film to be applied to the bonding step S101 is, for example, 0.5 to 3 m, preferably 1 to 2.5 m.

(1-2-2) Elastic modulus of protective film

The protective film for the bonding step S101 contains a region satisfying the following formula (I): TD elastic modulus-MD elastic modulus ≧300 MPa (I)

In the formula (I), the TD elastic modulus refers to the tensile elastic modulus (MPa) in the TD direction at a temperature of 23 ° C and a relative humidity of 55% RH, and the MD elastic modulus refers to a temperature of 23 ° C, relative Tensile modulus of elasticity (MPa) in the MD direction at a humidity of 55% RH.

The MD direction refers to the mechanical flow direction of the film, that is, the longitudinal direction of the film; the TD direction refers to the direction orthogonal to the MD direction.

By bonding the protective film including the above region to the polarizing plate and cutting out the sheet body from the region in the cutting step S102, that is, by providing the cut sheet body with the protection satisfying the formula (I) The film can be obtained as a polarizing plate sheet having a protective film which is sufficiently curled.

The above-mentioned "cutting of the sheet-like body from this region" means that the entire protective film of the cut sheet-like body is contained in this region.

Here, the curl of the polarizing plate sheet with the protective film may be classified into two types of "MD curl" and "TD curl" in addition to the classification of "positive curl" and "reverse curl". . "MD Curl" refers to a stress in a direction parallel to the MD direction of the "long strip-shaped polarizing plate with a protective film" to be cut out of the "polarizing plate sheet with a protective film" (contraction force) , expansion force, etc.) caused by the curl.

Specifically, the sample for measurement (sheet-like body) is cut out from a long polarizing plate with a protective film, and the measurement sample is made to have a concave side, according to the description of the item of the following description. When the method is placed on the water platform, it is possible to measure the angle of the "MD diagonal direction of the strip-shaped polarizing plate with the protective film in the two diagonal lines of the measurement sample to be small". The size of the upper 2 corners curled up. In the long polarizing plate with a protective film, when the absorption axis direction of the polarizing plate is parallel to the MD direction of the protective film, "MD diagonal" can be measured for the measurement sample. The angle between the absorption axis direction of the polarizing plate of the sample for measurement is two angles upward on the diagonal line (the curl in the absorption axis direction).

"TD Curl" refers to the stress in the direction parallel to the TD direction of the "long strip-shaped polarizing plate with a protective film" to be cut out of the "polarized plate sheet with a protective film" (contraction force) , expansion force, etc.) caused by the curl.

The present invention is directed to MD crimping. The positive crimp in the "polarizing sheet-like body with a protective film which is sufficiently curled" which can be produced according to the present invention means a positive crimp which is MD crimp. Hereinafter, this curl is also referred to as "MD positive curl".

The "satisfaction formula (I)" in the "protective film for the bonding step S101 includes the region satisfying the formula (I)" and the "cut-out sheet member having the protective film satisfying the formula (I)" And the entire protective film satisfies the formula (I), that is, the measurement is taken at any position of the protective film. With the sample, the TD elastic modulus and the MD elastic modulus measured according to the description of the items of the examples to be described later satisfy the formula (I).

According to the review by the present inventors, it is understood that when the complex point is measured along the TD direction of the generally obtainable protective film for the left side of the formula (I), the value of the left side varies greatly depending on the product lot number or the like. By. On the other hand, it is also known that when the complex point is measured along the MD direction of the generally obtainable protective film for the left side of the formula (I), the value on the left side does not largely vary in the same roll.

Therefore, it can be said that the protective film satisfying the formula (I) as a whole across the TD direction generally satisfies the formula (I) across the entire protective film (that is, the sample for measurement is taken from any position of the protective film). .

From the viewpoint of improving the yield of the polarizing plate sheet having the protective film, the above-mentioned region of the protective film preferably has a large occupied area as much as possible, and more preferably the region is expanded and attached to the step S101. At least the TD direction (width direction) of the protective film as a whole is more preferably extended to the entirety of the protective film.

From the viewpoint of increasing the MD positive curl of the obtained polarizing plate sheet with a protective film, 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 2000 MPa or less, and typically 1500 MPa or less.

For the protective film to be bonded to the step S101, the left side of the formula (I) for the obtained protective film and including the region satisfying the formula (I) can be used.

(1-3) Bonding of polarizing plate and protective film

Referring to Fig. 4, the bonding of the polarizing plate 2 and the protective film 1 can be performed, for example, using a pair of rolls (bonding rolls) 5, 5. From the viewpoint of production efficiency, this method is particularly advantageous when the polarizing plate 2 and the protective film 1 are elongated.

Specifically, when the long-length polarizing plate 2 is continuously conveyed, the long protective film 1 is continuously conveyed, and the protective film 1 is superposed on one surface of the polarizing plate 2 to pass through and sandwich a pair of stickers. Between the rolls 5 and 5, the polarizing plate 3 with the protective film attached to the two films can be manufactured.

The MD direction (transport direction) of the polarizing plate 2 and the MD direction (transport direction) of the protective film 1 are generally parallel. The parallel means that the angle between the MD direction of the polarizing plate 2 and the MD direction of the protective film 1 is 0 degree ± 5 degrees, preferably 0 degree ± 2 degrees.

From the viewpoint of increasing the MD positive curl of the obtained polarizing plate sheet with a protective film, it is preferable to laminate the two films so that the absorption axis of the polarizing plate 2 and the MD direction of the protective film 1 are parallel. . The parallel means that the angle between the absorption axis of the polarizing plate 2 and the MD direction of the protective film 1 is 0 degree ± 5 degrees, preferably 0 degree ± 2 degrees.

By passing the laminated body of the polarizing plate 2 and the protective film 1 between the pair of bonding rolls 5 and 5, the laminated body is pressed from above and below, so that the two films are adhered.

The polarizing plate 2 has a clear hard coat layer (a hard coating layer having a smooth surface) on the outermost surface thereof, and when the protective film 1 is attached to the transparent hard coat layer, between the polarizing plate 2 and the protective film 1 The adhesion is easily increased, and there is a tendency that the polarizing plate sheet having the protective film is sufficiently large in the MD curl can be easily obtained. Therefore, the polarizing plate 2 preferably has a transparent hard coat layer on its outermost surface (the surface is a smooth hard coat layer).

When the protective film 1 is composed of a base film and an adhesive layer laminated thereon, if the protective film 1 is placed on one surface of the polarizing plate 2 and passed between a pair of bonding rolls 5 and 5, Then, the adhesive layer of the protective film 1 is superposed so as to be in contact with the single surface of the polarizing plate 2. Before laminating 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 may be subjected to plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, Surface activation treatment such as saponification treatment.

In the step of bonding together by the pair of bonding rolls 5 and 5, the pressure (nip) applied to the laminate of the protective film 1 and the polarizing plate 2 is, for example, 0.01 to 0.5 MPa, and may be 0.05 to 0.3. MPa. As the bonding rolls 5 and 5, a conventionally known one may be used, such as a metal (including an alloy such as SUS) or a rubber.

In the step of bonding the polarizing plate 2 and the protective film 1 , it is preferable to apply the tension to the polarizing plate 2 and the protective film 1 , and it is more preferable to apply the tension of the polarizing plate 2 before the bonding to the protective film 1 . The tension is small before the fitting. Such tension control is advantageous for increasing the MD positive curl of the resulting polarizing plate sheet with a protective film. The tension before bonding refers to the tension applied to the MD direction of the film before the bonding of the two films (the laminated bodies of the two films pass through the pair of bonding rolls 5, 5), and can be measured according to the description of the items of the examples to be described later.

From the viewpoint of increasing the MD positive curl of the obtained polarizing plate sheet with a protective film, the pre-bonding tension of the polarizing plate 2 in the MD direction is preferably 250 N/m or less, more preferably 200 N/ m or less.

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

(2) cutting out step S102

This step is a step of cutting out the above-mentioned region satisfying the formula (I) in the protective film-attached polarizing plate 3 obtained in the step S101 to obtain a polarizing plate-like sheet having a protective film.

The cutting (cutting) can be performed by a conventionally known cutting means such as a cutting blade.

As described above, "cutting the sheet-like body from the region" means that the entire protective film of the cut sheet-like body is contained in the region.

The size, shape, and cut angle of the sheet of the polarizing plate with the protective film cut out are not particularly limited.

The polarizing plate sheet body with a protective film is preferably a square shape, and more preferably has a square shape of a long side and a short side. The square shape is preferably rectangular.

When the shape of the polarizing plate sheet having the protective film is a rectangle, 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.

In general, when the size of the polarizing plate sheet with the protective film is increased, the MD tends to be curled. Therefore, when the size of the polarizing plate sheet with the protective film is large, the left side of the formula (I) is preferably larger in order to impart a sufficient MD positive curl amount.

Although it is not particularly limited, if the shape of the polarizing plate sheet with the protective film is rectangular, the polarizing plate sheet with the protective film attached thereto can be viewed from the side of the protective film with respect to the long side and the short side thereof. The polarizing plate sheet having the protective film is cut out from the polarizing plate 3 with the protective film so that the absorption axis direction of the polarizing plate (the MD direction of the polarizing plate) is at an angle of 45 degrees.

Alternatively, if the shape of the polarizing plate sheet with the protective film is a rectangular shape, the polarizing plate can be absorbed with respect to the long side thereof when the polarizing plate sheet having the protective film is viewed from the side of the protective film. The polarizing plate sheet having the protective film is cut out from the polarizing plate 3 with the protective film in such a manner that the axial direction (the MD direction of the polarizing plate) is parallel or at an angle of 90 degrees.

<Polarizing plate sheet with protective film>

The polarizing plate sheet body with a protective film according to the present invention comprises a polarizing plate and a protective film laminated on one side thereof, and the protective film satisfies the following formula (II): The first elastic modulus - the second elastic modulus ≧ 300 MPa (II).

In the formula (II), the first elastic modulus refers to a tensile elastic modulus (MPa) in a direction orthogonal to the absorption axis of the polarizing plate at a temperature of 23 ° C and a relative humidity of 55% RH, and the second elasticity The modulus refers to a tensile elastic modulus (MPa) in a direction parallel to the absorption axis of the polarizing plate at a temperature of 23 ° C and a relative humidity of 55% RH.

By providing the protective film satisfying the formula (II), the polarizing plate sheet having the protective film can have a sufficiently large MD positive curl.

When a polarizing plate-like sheet having a protective film having a sufficiently large MD positive curl is used, even if one or more optical functional layers are laminated on the polarizing plate side to form the multilayer structure, When the state in which the reverse curl is not present (flat state) or the state in which the film is positively curled, the polarizing plate sheet or the multilayer structure having the protective film is bonded to the image display element via the adhesive layer. It is possible to suppress the occurrence of a bonding error or to suppress the incorporation of air bubbles into the interface between the adhesive layer and the image display element.

The polarizing plate sheet body with a protective film of the present invention can be produced by the above-described method for producing a polarizing plate sheet having a protective film.

When the polarizing plate sheet having the protective film is produced by the method for producing a polarizing plate sheet having the protective film, the protective film and the polarizing plate are formed in a direction orthogonal to the absorption axis of the polarizing plate. The TD direction is synonymous.

The term "satisfying formula (II)" means that the whole of the protective film satisfies the formula (II), that is, the sample for measurement is taken from any position of the protective film, and is determined according to the description of the item of the later-described embodiment. Both the first elastic modulus and the second elastic modulus satisfy the formula (II).

The reason for the same reason as described in the section [Manufacturing method of the polarizing plate sheet with a protective film] is that the polarizing plate sheet having the protective film is orthogonal to the absorption axis of the polarizing plate. The protective film of the formula (II) as a whole is generally satisfied that the entire protective film (that is, the sample for measurement is taken from any position of the protective film) satisfies the formula (II).

From the viewpoint of increasing the MD positive curl of the polarizing plate sheet with the protective film, the left side of the formula (II) is preferably 400 MPa or more, more preferably 500 MPa or more. The left side of the formula (II) is usually 2000 MPa or less, and typically 1500 MPa or less.

The size and shape of the polarizing plate sheet having the protective film are not particularly limited, and specific dimensions and shapes are described in the item "Manufacturing method of polarizing plate sheet with protective film". When the size of the polarizing plate sheet with the protective film is large, in order to impart a sufficient MD positive curl amount, the left side of the formula (II) is preferably larger.

The polarizing plate sheet body with the protective film (the polarizing plate sheet body with the protective film obtained by the method for producing the polarizing plate sheet body with the protective film according to the present invention is also the same) preferably shows MD positive Further, it is preferable that the crimping is performed even when the multilayer structure is formed, and the MD positive curl or the lithographic state without curling is displayed, and the MD positive crimp amount measured according to the description of the item of the following examples is 40 mm or more. The MD positive curl amount can be 45 mm or more. The MD positive curl amount is preferably 100 mm or less.

Although the shape of the polarizing plate sheet with the protective film is a rectangular shape, when the polarizing plate sheet having the protective film is viewed from the side of the protective film, the long side and the short side can be made. The absorption axis direction of the polarizing plate is an angle of 45 degrees.

Alternatively, when the shape of the polarizing plate sheet with the protective film is a rectangular shape, when the polarizing plate sheet having the protective film is viewed from the side of the protective film, the absorption axis direction of the polarizing plate can be made with respect to the long side thereof. Become parallel or become an angle of 90 degrees.

An example of the layer configuration of the polarizing plate sheet body with the protective film is shown in Fig. 5. As shown in FIG. 5, when the protective film 1 is composed of the base film 40 and the adhesive layer 50 laminated thereon, the adhesive film 50 of the protective film 1 is attached to the above-mentioned single sheet with the polarizing plate 2. The way the faces meet is overlapping.

A more specific description of the polarizing plate 2 and the protective film 1 is described in the item "Manufacturing method of a polarizing plate sheet with a protective film".

<Long strip of polarizing plate with protective film>

The polarizing plate with a protective film according to the present invention includes a "long polarizing plate" and a "stripe protective film laminated on one side thereof", and the protective film contains the following formula (III). Area: The first elastic modulus - the second elastic modulus ≧ 300 MPa (III).

In the formula (III), the first elastic modulus refers to a tensile elastic modulus (MPa) in a direction orthogonal to the absorption axis of the long polarizing plate at a temperature of 23 ° C and a relative humidity of 55% RH. The second elastic modulus refers to a tensile elastic modulus (MPa) in a direction parallel to the absorption axis of the elongated polarizing plate at a temperature of 23 ° C and a relative humidity of 55% RH.

When a "long-shaped polarizing plate with a protective film" including the above-mentioned region is used, the cut-out sheet has a protective film satisfying the formula (III) by cutting out the sheet-like body from the region. It is possible to obtain a polarizing plate sheet having a protective film which is sufficiently curled.

The above-mentioned "cutting of the sheet-like body from this region" means that the entire protective film of the cut sheet-like body is contained in the region.

The long polarizing plate-attached polarizing plate of the present invention can be produced by the bonding step S101 of the method for producing the polarizing plate-like sheet having the protective film.

When the polarizing plate with the protective film is manufactured in the bonding step S101 of the manufacturing method of the polarizing plate sheet with the protective film, the polarizing plate with the protective film is formed in the direction perpendicular to the absorption axis of the polarizing plate. It is synonymous with the protective film and the TD direction of the polarizing plate.

The term "satisfying formula (III)" means that the entire formula and the protective film satisfy the formula (III), that is, the sample for measurement is taken at any position of the protective film, and is determined according to the description of the item of the embodiment to be described later. Both the first elastic modulus and the second elastic modulus satisfy the formula (III).

According to the reason described in the item of <The manufacturing method of the polarizing plate sheet with a protective film>, the absorption of the polarizing plate with a protective film is carried out in the strip-shaped polarizing plate with a protective film. The protective film of the formula (III), in which the axis is orthogonal to the entire direction, generally satisfies the formula (III) across the entire protective film (that is, the sample for measurement is taken from any position of the protective film).

From the viewpoint of increasing the yield of the polarizing plate sheet with the protective film, the above-mentioned region of the protective film preferably has a large occupied area as much as possible, and more preferably the region is expanded for the laminating step. The protective film of S101 has at least the entire width direction, and more preferably extends the entire protective film.

From the viewpoint of increasing the MD positive curl of the "protective film-attached polarizing plate sheet" which is cut out from the "long strip-shaped polarizing plate with a protective film", the left side of the formula (III) is Preferably, it is 400 MPa or more, more preferably 500 MPa or more. The left side of the formula (III) is usually 2000 MPa or less, and typically 1500 MPa or less.

The size, shape, and cutting angle of the polarizing plate sheet with the protective film are not particularly limited, and the specific size, shape, and cutting angle are referred to as the "manufacturing method of the polarizing plate sheet with the protective film" item. The record. When the size of the "polarizing plate sheet with a protective film" which is cut out from the "long-shaped polarizing plate with a protective film" is large, in order to sufficiently impart the amount of MD positive curl, sometimes (III) The left side of the ) is preferably larger.

The length of the strip-shaped polarizing plate with a protective film is, for example, 100 to 20,000 m, preferably 1,000 to 10,000 m. Further, the width of the long polarizing plate with the protective film is, for example, 0.5 to 3 m, preferably 1 to 2.5 m.

A more specific description of the layer structure of the "long-length polarizing plate with a protective film" and the polarizing plate and the protective film constituting the "long-shaped polarizing plate with a protective film" are referred to as "protected" Description of the method for producing a polarizing plate sheet of a film> and the <Polarizing plate sheet with a protective film> item.

<Multilayer structure>

On the side of the polarizing plate on the "polarizing plate with protective film" or "long-shaped polarizing plate with protective film", it is possible to laminate another layer or more with an adhesive layer or an adhesive layer. An optical functional layer or a separation membrane (release film) or the like.

The optical functional layer may be a retardation layer or the like, and the optical functional layer may be laminated on the surface of the polarizing plate via an adhesive layer or an adhesive layer.

[Examples]

Hereinafter, the present invention will be more specifically described by showing experimental examples, but the present invention is not limited to the examples.

In the following experimental examples, the thickness of the polarizing plate and the film, the difference in the elastic modulus of the protective film, the pre-bonding tension of the polarizing plate and the protective film in the MD direction, and the polarizing plate-like body with the protective film The MD crimp amount was measured in the following manner.

(1) Thickness of polarizing plate and film

It was measured using a digital micrometer "MH-15M" manufactured by Nikon Co., Ltd.

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

A rectangular piece having a long side of 100 mm × a short side of 25 mm was cut out from a long strip of a polarizing plate with a protective film using a supercutter. The cutting is performed such that the long side of the small piece is parallel to the MD direction of the long polarizing plate with the protective film, and the short side of the small piece and the long TD of the polarizing plate with the protective film attached thereto The directions are in a parallel manner. The small piece was peeled off from the polarizing plate, and the obtained small piece of the protective film monomer was used as a sample for measurement of the MD elastic modulus.

Further, similarly, a rectangular cutting piece having a long side of 100 mm × a short side of 25 mm was cut out from a long strip-shaped polarizing plate with a protective film using a super cutter. However, the cutting is performed such that the long side of the small piece is parallel to the TD direction of the long polarizing plate with the protective film, and the short side and the long strip of the protective film are attached to the polarizing plate. The MD direction is performed in a parallel manner. The small piece was peeled off from the polarizing plate, and the obtained small piece of the protective film was used as a sample for measurement of the TD elastic modulus.

Next, the upper and lower jigs of a tensile tester (Autograph AG-Xplus tester manufactured by Shimadzu Corporation) were used so that the distance between the jigs was 5 cm. In the formula, the sample for measurement is stretched in the longitudinal direction of the sample for measurement at a tensile rate of 1 mm/min in an environment of 23 ° C and a relative humidity of 55%. The slope of the straight line between 3 and 6 MPa in the obtained stress-strain curve was calculated as a tensile elastic modulus [MPa] at 23 ° C and a relative humidity of 55%. At this time, only the thickness value of the biaxially stretched polyethylene terephthalate (base film) was used as the thickness for calculating the stress.

The tensile elastic modulus calculated from the sample for measuring the MD elastic modulus is the MD elastic modulus, and the tensile elastic modulus calculated from the sample for measuring the TD elastic modulus is the TD elastic modulus.

In each of the following experimental examples, the polarizing plate with the protective film is produced by bonding the two films so that the absorption axis (MD direction) of the polarizing plate is parallel to the MD direction of the protective film, so the above formula ( The TD elastic modulus in I) is synonymous with the first elastic modulus in the above formulas (II) and (III), and the MD elastic modulus in the above formula (I) and the above formula (II) and The second elastic modulus in (III) is synonymous.

Hereinafter, the TD elastic modulus (first elastic modulus) is simply referred to as "TD elastic modulus", and the MD elastic modulus (second elastic modulus) is simply referred to as "MD elastic modulus".

The TD elastic modulus-MD elastic modulus (first elastic modulus - second elastic modulus) was calculated from the obtained TD elastic modulus and MD elastic modulus.

Hereinafter, the TD elastic modulus-MD elastic modulus (first elastic modulus - second elastic modulus) is simply referred to as "elastic modulus difference".

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

The film tension of the polarizing plate and the protective film between the "adhesive roller for bonding one of the polarizing plate and the protective film" and the "pinch roller closest to the bonding roller" [N/m], The tension was measured by using a tension detecting roller provided between the "bonding roller" and the "pinch roller closest to the bonding roller" as the tension before bonding in the MD direction.

(4) MD curl amount of the polarizing plate sheet body with the protective film

As shown in Fig. 6, from the obtained polarizing plate 60 with a protective film, the absorption axis 61 of the polarizing plate is made 45 degrees with respect to the long side and the short side when viewed from the side of the protective film. In the manner, a small piece (sheet-like body) of a rectangular shape (long side 140 mm × short side 70 mm) was cut out using a super cutter, and this was used as a sample 70 for measurement of the MD crimp amount. The cutting of the sample for measurement 70 was carried out immediately after laminating the polarizing plate and the protective film at 23 ° C and a relative humidity of 55%.

The sample 70 for measurement was placed on the reference surface (water platform) with the concave side facing upward. In this state, the two angles 80 on the diagonal line in which the angle of the absorption axis direction of the polarizing plate of the measurement sample 70 in the two diagonal lines of the measurement sample 70 is smaller are measured. The height from the reference plane is calculated as the average value of the heights of the two corners 80 as the MD curl amount [mm].

The state in which the protective film side is concave is in a state of being positively curled, and the state in which the polarizing plate side is in a concave shape is in a state of having reverse curl. In the following Experimental Examples 1 to 3, any of the samples for measurement (the polarizing plate-like sheet with the protective film) had positive curl.

<Experimental Examples 1 to 3>

(A) Production of polarizer

The long-length polyvinyl alcohol film (average degree of polymerization: about 2400, saponification degree: 99.9 mol% or more, thickness: 30 μm) is continuously conveyed while being dry-axially extended to about 4 times, and further kept in tension. In the state, after immersing in pure water at 40 ° C for 1 minute, it was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.1/5/100 at 28 ° C for 60 seconds. Thereafter, it was immersed at 68 ° C for 300 seconds in an aqueous solution of potassium iodide / boric acid / water in a weight ratio of 10.5 / 7.5 / 100. Then, After washing with pure water of 5 ° C for 5 seconds, it was dried at 70 ° C for 180 seconds to obtain a long-polarized polarizer having an axis of iodine adsorbed by a polyvinyl alcohol film. The thickness of the polarizer was 13 μm.

(B) Production of polarizing plate

The long-length polarizing film obtained in the above (A) is continuously conveyed, and the first thermoplastic resin film (the product name "COP25ST-HC" which is a transparent hard coat film manufactured by Nippon Paper Industries Co., Ltd.) is used. A film formed of a transparent hard coat layer on a cyclic polyolefin resin film, having a thickness of 29 μm] and a long second thermoplastic resin film (manufactured by Fujifilm Co., Ltd. as a cellulose triacetate (TAC) film) The product name "ZRG20SL", thickness: 20 μm] is continuously conveyed, and a pair of bonding rolls are passed through between the polarizer and the first thermoplastic resin film and between the polarizer and the second thermoplastic resin film. A laminated film composed of the first thermoplastic resin film/water-based adhesive layer/polarizer/water-based adhesive layer/second thermoplastic resin film was obtained.

Then, the obtained laminated film was conveyed by a hot air dryer at 80 ° C for 300 seconds, and the aqueous adhesive layer was dried to obtain a long polarizing plate.

In the water-based adhesive, the following aqueous solution is used: a polyvinyl alcohol powder (trade name "GOHSEFIMER" manufactured by Nippon Synthetic Chemical Co., Ltd., average polymerization degree: 1100) is dissolved in hot water at 95 ° C to obtain a concentration of 3 In a polyvinyl alcohol aqueous solution of a weight %, a crosslinking agent [sodium glyoxylate manufactured by Nippon Synthetic Chemical Co., Ltd.) is mixed at a ratio of 1 part by weight based on 10 parts by weight of the polyvinyl alcohol powder. An aqueous solution. The thickness of the obtained polarizing plate was 62 μm.

(C) Production of a long strip of polarizing plate with a protective film

The long-length polarizing plate obtained in the above (B) is continuously conveyed, and the long protective film of the peeled separation film (the biaxially stretched polyethylene terephthalate (thickness: 38 μm)) The product name "AY-4212" manufactured by Fujimori Kogyo Co., Ltd., which has a (meth)acrylic resin adhesive layer (thickness: 15 μm), is continuously conveyed, and these are superimposed and passed through a pair of bonding rolls. In the meantime, the laminate of the protective film and the polarizing plate is pressed from above and below, and a long polarizing plate with a protective film is continuously produced.

The protective film is bonded to the surface of the first thermoplastic resin film (transparent hard coat film) of the polarizing plate via the adhesive layer.

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

The manufacturing method of the polarizing plate with the protective film attached to the strip shape of the experimental examples 1 to 3 was the same except that the protective film used was the same (commodity is the same, but the lot number is different). Hereinafter, the protective films used in Experimental Examples 1 to 3 are referred to as protective films 1 to 3, respectively.

With respect to the obtained long strip-shaped polarizing plate with a protective film, the TD elastic modulus, the MD elastic modulus, and the elastic modulus difference were obtained according to the above method.

The protective films 1 to 3 each have a width of 1300 mm (length in the TD direction). When measuring the elastic modulus of each protective film, it is determined to be 100 mm, 280 mm, 470 mm, 650 mm, 830 mm, 1020 mm, and 1200 mm in one direction from the width direction in any of the arbitrary MD direction positions. The sample for measurement was cut out at the position of the point, and the TD elastic modulus, the MD elastic modulus, and the elastic modulus difference were obtained for each of the seven measurement samples. The results of these are shown in the column "1" of Table 1. Count from any of the above arbitrary MD directions and along In the MD direction and the distance of 20 mm, seven samples for measurement were cut out in the same manner as described above, and the TD elastic modulus, the MD elastic modulus, and the elastic modulus difference were obtained for each of the seven measurement samples. The results of these are shown in the column "2" of Table 1. Seven measurement samples were cut out in the same manner as described above from the position in the arbitrary MD direction and at a distance of 50 mm in the MD direction, and the TD elastic molds were obtained for each of the seven measurement samples. Number, MD elastic modulus and elastic modulus difference. The results of these are shown in the "3" column of Table 1.

Further, a graph showing the relationship between the "width direction position" of the protective films 1 to 3 and the "elastic modulus difference (the elastic modulus described in the column of "1" in Table 1) is shown in Fig. 7.

For the position at which the sample for measurement is cut out, for example, "the sample for measurement is cut at a position of 100 mm from one end in the width direction" means "a position of 100 mm from one end in the width direction" and "measurement" The sample for measurement was cut out in such a manner that the center position in the width direction of the sample was uniform. The other positions from the one end in the width direction are also the same.

As shown in Tables 1 and 7, it can be seen that the long protective films 1 and 2 include the span and the whole (that is, the entire direction across the TD direction (the direction orthogonal to the absorption axis of the long polarizing plate) And satisfying the regions of the formulas (I) and (III) across the entire MD direction (absorption axis direction of the long polarizing plate), and the region spans the entire width direction of the protective film.

On the other hand, the long protective film 3 includes the entire TD direction (the direction orthogonal to the absorption axis of the long polarizing plate) and the entire MD direction (the absorption of the long polarizing plate) The axial direction) satisfies the regions of the formulae (I) and (III), but the region does not span the entire width direction of the protective film. In other words, in the long protective film 3, the regions (I) and (III) satisfy only the region from the one end in the width direction to about 700 mm from the one end.

Further, as described above, the protective films satisfying the formulae (I) and (III) in any of the arbitrary MD direction positions generally satisfy the formulas (I) and (III) in other MD direction positions.

(D) Production of a polarizing plate sheet with a protective film

As shown in Fig. 6, in the long polarizing plate-attached polarizing plate obtained in the above (C), the absorption axis of the polarizing plate is 45 with respect to the long side and the short side when viewed from the side of the protective film. In a manner of a degree, a small piece (sheet body) of a rectangular shape (long side 140 mm × short side 70 mm) was cut out using a super cutter, and a polarizing plate sheet body with a protective film was obtained.

With respect to the obtained polarizing plate sheet with a protective film, the amount of MD curl was measured in accordance with the above method.

The polarizing plates with the protective films attached to the strips of Experimental Examples 1 to 3 each had a width of 1330 mm (length in the TD direction). When the MD curl amount is measured for the polarizing plate sheet having the protective film obtained by the polarizing plate having the protective film attached thereto, it is in an arbitrary MD direction position, along the width direction, in the slave One end of the width direction is counted as 100mm, 280mm, 470mm, A polarizing plate sheet having a protective film was cut out at a position of 7 o'clock at 650 mm, 830 mm, 1020 mm, and 1200 mm, and the amount of MD curl of the seven sheets was measured. Seven sheets of the sheet-like system were cut out from the vicinity of the cut-out position of the sample for measurement in which the difference in elastic modulus of the protective film described in the column "1" of Table 1 was measured. The results are shown in Table 2. Further, in Experimental Examples 1 to 3, "the position in the width direction of the polarizing plate-like sheet with the protective film cut out from the long polarizing plate-attached polarizing plate" and "the cut-out protective film are shown" A graph showing the relationship between the amount of MD curl of the sheet of the polarizing plate is shown in Fig. 7.

In the position where the polarizing plate sheet having the protective film is cut out, for example, "the polarizing plate-like sheet with the protective film is cut at a position of 100 mm from one end in the width direction" means " The polarizing plate-like sheet with the protective film is cut out so that the position at the position of 100 mm from the one end in the width direction coincides with the center position in the width direction of the sheet-like body of the polarizing plate with the protective film. The other positions from the one end in the width direction are also the same.

The polarizing plate-like sheets with the protective film cut out from the long polarizing plate with the protective film of Experimental Examples 1 to 3 all have positive curl. Therefore, the measured MD crimp amount is the amount of MD positive curl.

7 sheets of the polarizing plate-like sheet with a protective film and 7 sheets of the polarizing plate with the protective film attached to the long protective film 1 of the protective film 1 and Experimental Example 2 using the protective film 2 In the polarizing plate-like sheet with the protective film attached to the 7 sheets of the polarizing plate with the protective film attached thereto, the protective film laminated on the polarizing plate satisfies the formula (II).

In the polarizing plate-like sheet with a protective film which is cut out from the long polarizing plate with the protective film of the experimental example 3 using the protective film 3, it is protected from the strip shape. The protective film laminated on the polarizing plate in the sheet-like body cut out at the position of 100 mm, 280 mm, 470 mm, and 650 mm from one end in the width direction of the polarizing plate of the film satisfies the formula (II), but at 830 mm, 1020 mm, and 1200 mm. The sheet-like body cut at the position is not satisfied.

As shown in Table 2 and Fig. 8, the polarizing plate sheet system which satisfies the protective film of the formula (II) exhibits an MD positive crimp amount of 40 mm or more. On the other hand, the MD positive crimp amount of the polarizing plate sheet body which does not satisfy the protective film of the formula (II) is less than 40 mm.

Claims (11)

A method for producing a polarizing plate sheet with a protective film, comprising the steps of: bonding a protective film comprising a region satisfying the following formula (I) to one side of a polarizing plate to obtain a protective film; a step of polarizing the plate; and a step of cutting out the sheet-like body of the polarizing plate with the protective film from the aforementioned region; TD elastic modulus-MD elastic modulus ≧300 MPa (I) where TD elastic modulus refers to temperature The tensile elastic modulus in the TD direction at 23 ° C and the relative humidity of 55% RH, and the MD elastic modulus refers to the tensile elastic modulus in the MD direction at a temperature of 23 ° C and a relative humidity of 55% RH. The manufacturing method according to the first aspect of the invention, wherein the polarizing plate and the protective film are sandwiched between a pair of rolls and bonded together. The manufacturing method according to claim 2, wherein the polarizing plate has a long shape, and the protective film has a long shape. The manufacturing method according to the third aspect of the invention, wherein the pre-bonding tension of the polarizing plate is 200 N/m or less, and the pre-bonding tension of the protective film is 300 N/m or more. The production method according to any one of claims 1 to 4, wherein the absorption axis of the polarizing plate is bonded to the MD direction of the protective film in parallel. The production method according to any one of claims 1 to 4, wherein the polarizing plate has a thickness of 70 μm or less. A polarizing plate sheet body with a protective film, comprising: a polarizing plate; and a protective film laminated on one side thereof; The protective film satisfies the following formula (II), the first elastic modulus - the second elastic modulus ≧ 300 MPa (II), and the first elastic modulus means a temperature of 23 ° C and a relative humidity of 55% RH. The second elastic modulus is a parallel to the absorption axis of the polarizing plate at a temperature of 23 ° C and a relative humidity of 55% RH, in a tensile elastic modulus in a direction orthogonal to the absorption axis of the polarizing plate. The tensile modulus of elasticity in the direction. The polarizing plate-like sheet with a protective film as described in claim 7, wherein the surface of the polarizing plate side is convex and the amount of curling in a direction parallel to the absorption axis of the polarizing plate is 40mm or more. The polarizing plate sheet body with a protective film as described in claim 7 or 8, wherein the polarizing plate has a thickness of 70 μm or less. A long strip-shaped polarizing plate with a protective film, comprising: a long polarizing plate; and a long protective film laminated on one side thereof; wherein the protective film comprises the following formula (III) In the region, the first elastic modulus - the second elastic modulus ≧ 300 MPa (III), the first elastic modulus refers to the long polarizing plate at a temperature of 23 ° C and a relative humidity of 55% RH. The absorption axis is a tensile elastic modulus in the orthogonal direction, and the second elastic modulus is in a direction parallel to the absorption axis of the long polarizing plate at a temperature of 23 ° C and a relative humidity of 55% RH. The tensile modulus of elasticity. The polarizing plate with a protective film as described in claim 10, wherein the region spans the entire width direction of the protective film.