JP2019101428A - Method for manufacturing sheets of protection film-coated polarizer - Google Patents

Abstract

To provide a method allowing manufacture of sheets of a protection film-coated polarizer which have relatively large regular curl.SOLUTION: A method for manufacture of sheets of a protection film-coated polarizer comprises: bonding a protection film including an area satisfying the formula, (TD elastic modulus)-(MD elastic modulus)≥300 MPa, to a single face of a polarizer to obtain a protection film-coated polarizer; and cutting out sheets of the protection film-coated polarizer from the area. In the formula, the TD elastic modulus is the tensile modulus in the TD direction at the temperature of 23°C and the relative humidity of 55%RH, and the MD elastic modulus is the tensile modulus in the MD direction at the temperature of 23°C and the relative humidity of 55%RH.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a polarizing plate sheet with a protective film. The present invention also relates to a polarizing plate with a protective film, and a polarizing plate with a long protective film.

  BACKGROUND In recent years, image display devices such as liquid crystal display devices and organic EL display devices, for example, mobile terminals such as smartphones, are rapidly advancing in screen size and slimming in terms of design and portability. In order to realize driving for a long time with a limited thickness, there is also a demand for increasing the brightness and reducing the thickness and weight of the polarizing plate used.

  As a polarizing plate, what laminated | stacked the protective film which consists of triacetyl cellulose (TAC) with the adhesive agent conventionally to the polarizer which consists of polyvinyl alcohol-type resin is used generally. However, 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

With the demand for thinner polarizing plates, thinner polarizers and protective films have been developed. A sheet of a polarizing plate which can be obtained by cutting it out from a thin, non-rigid polarizing plate, in particular a long polarizing plate, is prone to bowing deformation. In this specification, this deformation is also referred to as "curling".
The polarizing plate is generally marketed as a polarizing plate with a protective film on which a peelable protective film (also referred to as a surface protective film) for protecting the surface is attached. Also in the protective film-attached polarizing plate, the tendency that curling easily occurs when the sheet is made thin is the same.

There are two types of curling of a protective film-attached polarizing plate sheet, “positive curl” and “reverse curl”. In a sheet of protective film with a protective film consisting of a laminate of a polarizing plate and a protective film, “positive curl” is a curl having a convex surface on the polarizing plate side, and “reverse curl” is on the protective film side. A curl with a convex surface.
When reverse curling occurs, a bonding error occurs when bonding the polarizing plate side of the protective film-attached polarizing plate to an image display element such as a liquid crystal cell or an organic EL element through an adhesive layer. This is likely to cause a problem that air bubbles are mixed in the interface between the pressure-sensitive adhesive layer and the image display element.

The protective film-attached polarizing plate may be formed into a further multilayer structure by further laminating one or more other optical functional layers or the like on the polarizing plate side via an adhesive layer or an adhesive layer. In this case, the addition of the additional layer to the protective film-attached polarizing plate acts in the direction of reverse curling of the multilayer structure.
Therefore, in consideration of the multi-layered structure, it is desirable that the protective film-attached polarizing plate sheet has a sufficiently large positive curl. When the multilayer structure has a reverse curl, the above-mentioned failure is likely to occur when the multilayer structure is pasted to the image display element.
On the other hand, when the protective film-attached polarizing plate is bonded to the image display element as it is without being the multilayer structure, the large positive curl it has does not hinder the bonding to the image display element.

An object of the present invention is to provide a method capable of producing a protective film-attached polarizing plate sheet having a relatively large positive curl.
Another object of the present invention is to provide a polarizing plate sheet with a protective film which can have a relatively large positive curl.
Still another object of the present invention is to provide a long protective film-attached polarizing plate which can give a protective film-attached polarizing plate sheet having a relatively large positive curl.

The present invention provides the following method for producing a polarizing plate with a protective film, a polarizing plate with a protective film, and a polarizing plate with a long protective film.
[1] A process of obtaining a polarizing plate with a protective film by bonding a protective film including a region satisfying the following formula (I) on one side of a polarizing plate,
Cutting out a sheet of the polarizing plate with a protective film from the area;
The manufacturing method of the polarizing plate sheet material body with a protective film containing.
TD elastic modulus-MD elastic modulus 300 300MPa (I)
[In the formula, TD elastic modulus is a tensile elastic modulus in the TD direction at a temperature of 23 ° C. and a relative humidity of 55% RH, and MD elastic modulus is in the MD direction at a temperature of 23 ° C. and a relative humidity of 55% RH. It is a tensile elastic modulus. ]
[2] The production method according to [1], wherein the polarizing plate and the protective film are sandwiched between a pair of rolls and pasted.
[3] The manufacturing method according to [2], wherein the polarizing plate is long and the protect film is long.
[4] The tension before bonding of the polarizing plate is 200 N / m or less,
The manufacturing method according to [3], wherein the tension before bonding of the protective film is 300 N / m or more.
[5] The manufacturing method in any one of [1]-[4] bonded so that the absorption axis of the said polarizing plate and MD direction of the said protective film may become parallel.
[6] The method according to any one of [1] to [5], wherein the thickness of the polarizing plate is 70 μm or less.
[7] including a polarizing plate and a protective film laminated on one side of the polarizing plate,
The polarizing plate sheet having a protective film, wherein the protective film satisfies the following formula (II).
1st elastic modulus-2nd elastic modulus 300 300MPa (II)
[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. ]
[8] The polarizing plate with a protective film according to [7], wherein a curl amount in a direction parallel to the absorption axis of the polarizing plate having a convex surface on the polarizing plate side is 40 mm or more.
[9] The polarizing plate sheet according to [7] or [8], wherein the polarizing plate has a thickness of 70 μm or less.
[10] A long polarizing plate and a long protective film laminated on one side thereof,
A long polarizing plate with a protective film, wherein the protective film comprises a region satisfying the following formula (III).
1st elastic modulus-2nd elastic modulus 300 300MPa (III)
[Wherein, the first elastic modulus is a tensile elastic modulus 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, and the second elastic modulus is It is a tensile elastic modulus 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. ]
[11] The long protective film with polarizing plate according to [10], wherein the region covers the entire width direction of the protective film.

It is possible to provide a method capable of producing a protective film-attached polarizing plate sheet having a relatively large positive curl.
It is possible to provide a polarizing plate sheet with a protective film which can have a relatively large positive curl.
It is possible to provide a long protective film-attached polarizing plate capable of providing a protective film-attached polarizing plate sheet having a relatively large positive curl.

It is a flowchart which shows the manufacturing method of a polarizing plate sheet with a protective film. 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 side view which shows an example of bonding process S101 which bonds a polarizing plate and a protect film. It is a schematic sectional drawing which shows an example of the laminated constitution of a polarizing plate sheet with a protective film. It is the schematic explaining the preparation method of the sample for measurement of MD curl amount, and the measurement point of MD curl amount. It is a graph which shows the relationship of the width direction position of the protective films 1-3 used in Experimental example 1-3 respectively, and an elastic modulus difference. Experimental Examples 1 to 3 show the relationship between the width direction position of cutting out a sheet of protective film with a protective film from the long sheet of protective film with a protective film and the MD curling amount of the sheet of protective film with a cut out. It is a graph.

<Producing method of polarizing plate sheet with protective film>
Referring to FIG. 1, the method for producing a polarizing plate sheet with a protective film according to the present invention comprises the following steps:
A protective film is bonded on one side of a polarizing plate to obtain a protective film-attached polarizing plate S101, and a cutting-out step S102 for cutting out a sheet of the protective film-attached polarizing plate
including. Each step will be described in detail below.
As used herein, "sheet" refers to smaller sized films cut from larger sized films (e.g., long (strip) films).

(1) Bonding process S101
(1-1) Polarizing Plate Provided in Bonding Step S101 (1-1-1) Configuration of Polarizing Plate The polarizing plate is a polarizing element including at least a polarizer, and is usually bonded to one side or both sides thereof. And a thermoplastic resin film.
The thermoplastic resin film can be a protective film for protecting a polarizer, another optical film having an optical function different from that of a polarizer, or the like. Examples of other optical films are retardation films, brightness enhancement films and the like.
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 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 is usually 150 μm or less, preferably 100 μm or less, more preferably 100 μm or less, from the viewpoint of thinning of the polarizing plate and from the viewpoint of facilitating production of a sheet of protective film with a protective film having a sufficiently large positive curl. Is 80 μm or less, more preferably 70 μm or less.
The thickness of the polarizing plate is usually 20 μm or more or 30 μm or more.

Although the example of a layer structure of a polarizing plate 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.

It is preferable that the polarizing plate provided to bonding process S101 is elongate form.
The length of the elongate polarizing plate provided to bonding process S101 is 100-20000 m, for example, Preferably it is 1000-10000 m. Moreover, the width | variety of the elongate polarizing plate provided to bonding process S101 is 0.5-3 m, for example, Preferably it is 1-2.5 m.

(1-1-2) Polarizer The polarizer 10 constituting the polarizing plate 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 thinning of the polarizing plate, 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.
On the other hand, the thickness of the polarizer 10 is preferably large from the viewpoint of facilitating production of a sheet of protective film with a protective film having a sufficiently large positive curl, and specifically, preferably 10 μm or more, more preferably 15 μm. The thickness is more preferably 20 μm or more.

(1-1-3) 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. Film composed of a thermoplastic 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, by stretching (uniaxial stretching or biaxial stretching, etc.) a thermoplastic resin film made of the above material, or forming a liquid crystal layer or the like on the film, a retardation to which an arbitrary retardation value is imparted It can be a film. 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 thickness of the first thermoplastic resin film 20 and the second thermoplastic resin film 30 is preferably small from the viewpoint of facilitating the production of a sheet of protective film with a protective film having a sufficiently large positive curl, specifically, Preferably it is 40 micrometers or less, More preferably, it is 30 micrometers or less.

  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. Furthermore, they may have the same retardation characteristic or may have different retardation characteristics. The present invention is particularly advantageous in such a case, since curling tends to occur particularly in the sheet of protective film-attached polarizing plate when the configurations of the thermoplastic resin films bonded to both sides are different.

(1-1-4) 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

(1-2) Protecting Film Provided in Bonding Step S101 (1-2-1) Configuration of Protecting Film The protecting film is a film for protecting the surface of a polarizing plate, and usually, for example, an image display element etc. In the case of having a pressure-sensitive adhesive layer after the protective film-attached polarizing plate sheet is laminated, the pressure-sensitive adhesive layer is peeled and removed together. Therefore, the protect film 1 is releasably bonded to the surface of the polarizing plate 2.

The protective film can be composed of, for example, a base film and a pressure-sensitive adhesive layer laminated thereon.
The base film 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 resin It can be made of resin or the like. The substrate film may have a single layer structure or a multilayer structure.
The pressure-sensitive adhesive layer 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 may be a resin film having self-adhesiveness such as polypropylene resin and polyethylene resin. In this case, the protective film does not have an adhesive layer.

  The thickness of the protect film 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). is there. When the thickness of the protective film is less than 5 μm, the protection of the polarizing plate may be insufficient, and the handling is also disadvantageous. If the thickness of the protective film exceeds 150 μm, it is disadvantageous in terms of thinning of the protective film-attached polarizing plate sheet and rework of the protective film.

The protect film to be subjected to the bonding step S101 is preferably long.
The length of the long protective film to be subjected to the bonding step S101 is, for example, 100 to 20000 m, and preferably 1000 to 10000 m. Moreover, the width | variety of the elongate protective film provided to bonding process S101 is 0.5-3 m, for example, Preferably it is 1-2.5 m.

(1-2-2) Elastic Modulus of Protecting Film The protecting film to be subjected to the bonding step S101 has the following formula (I):
TD elastic modulus-MD elastic modulus 300 300MPa (I)
Including the region that satisfies
In the formula (I), TD elastic modulus is a tensile elastic modulus (MPa) in the TD direction at a temperature of 23 ° C. and a relative humidity of 55% RH, and MD elastic modulus is a temperature of 23 ° C. and a relative humidity of 55% RH Modulus of elasticity in the MD direction (MPa).
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.

By bonding a protective film including the above area to a polarizing plate and cutting out a sheet from the area in the cutting step S102, that is, by providing the protective film satisfying the formula (I). A sheet with a protective film with a sufficiently large positive curl can be obtained.
The above-mentioned "cut out the sheet from the area" means that the whole of the protect film of the cut sheet is included in the area.

Here, the curl of the protective film-attached polarizing plate sheet can be classified into two types, "MD curl" and "TD curl", separately from the above-mentioned classification of "positive curl" and "reverse curl". . "MD curl" refers to a curl that occurs due to stress (contraction force, expansion force, etc.) in a direction parallel to the MD direction of a long protective film-attached polarizing plate from which a protective film-attached polarizing plate is cut out. It is.
Specifically, in the MD curl, a measurement sample (sheet) is cut out from the long protective film-attached polarizing plate according to the description of the example described later, and the measurement sample has the concave side up. When placed on a very flat table, of the two diagonals of the measurement sample, the two diagonal corners with the smaller angle with the MD direction of the long protective film-attached polarizing plate lift up Its size can be measured as a curl. 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 polarizing plate of the measuring sample of the two diagonal lines of the measuring sample. It can be measured as a curl (curling in the absorption axis direction) in which two diagonally opposite corners with a smaller angle with the absorption axis direction are lifted.
"TD curl" refers to a curl caused by stress (contraction force, expansion force, etc.) in the direction parallel to the TD direction of a long protective film-attached polarizing plate from which a protective film-attached polarizing plate is cut out. It is.

  The present invention focuses on MD curl. The term "positive curl in a sheet having a protective film with a sufficiently large positive curl" which can be produced by the present invention refers to a positive curl which is an MD curl. Hereinafter, this curl is also referred to as "MD positive curl".

  The formula (I) in the above-mentioned "the protect film to be subjected to the bonding step S101 includes the region satisfying the formula (I)" and "the cut sheet is provided with the protect film satisfying the formula (I)" “To fill” means that the TD elastic modulus and the MD elastic modulus measured according to the description of the examples described later, regardless of the position of the protective film, ie, at any position of the protective film It means that the formula (I) is satisfied.

According to the study of the present inventor, when plural points on the left side of the formula (I) are measured along the TD direction of a generally available protect film, relatively large fluctuation in the numerical value of the left side is caused according to the product lot and the like. It has become clear that what is happening is present. On the other hand, when the left side of the formula (I) was measured at a plurality of points along the MD direction of a generally available protect film, it was also found that the numerical value of the left side does not have a relatively large fluctuation within the same roll.
Therefore, a protective film satisfying formula (I) over the entire TD direction usually satisfies formula (I) over the entire protective film (that is, regardless of the position of the protective film from which a measurement sample is taken). It can be said.

  From the viewpoint of increasing the yield of the protective film-attached polarizing plate sheet, the above-mentioned region of the protective film preferably has an occupied area as large as possible, and the region is a protective film to be subjected to the bonding step S101. It is more preferably at least the entire TD direction (width direction), and even more preferably the entire protective film.

  From the viewpoint of increasing the MD positive curl of the protective film-attached polarizing plate sheet obtained, 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 to be subjected to the bonding step S101, the left side of the formula (I) of the obtained protect film may be measured, and a film including a region satisfying the formula (I) may be used.

(1-3) Bonding of Polarizing Plate and Protecting Film Referring to FIG. 4, bonding of the polarizing plate 2 and the protective film 1 is performed using, for example, a pair of rolls (bonding rolls) 5 and 5. be able to. 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.

Specifically, the long polarizing plate 2 is continuously conveyed, and the long protective film 1 is continuously conveyed, and the protective film 1 is overlapped on one side of the polarizing plate 2 to form a pair of bonding rolls. By sandwiching the film between 5 and 5, it is possible to manufacture a protective film-provided polarizing plate 3 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 °.
From the viewpoint of increasing the MD positive curl of the obtained protective film-attached polarizing plate sheet, it is preferable to bond the two films so that the absorption axis of the polarizing plate 2 and the MD direction of the protective film 1 become parallel. 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 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 It is easy to increase the adhesion between the film and No. 1 so that the protective film-attached polarizing plate sheet having a sufficiently large MD positive curl tends to 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.

  In the case where the protective film 1 is composed of a base film and a pressure-sensitive adhesive layer laminated thereon, the protective film 1 is superposed on one side of the polarizing plate 2 and passed between the pair of bonding rolls 5 and 5 The pressure-sensitive adhesive layer of the protective film 1 is overlapped so as to be in contact with the one surface 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.

  In the step of bonding by the pair of bonding rolls 5 and 5, the pressure (nip pressure) applied to the laminate of the protect film 1 and the polarizing plate 2 is, for example, 0.01 to 0.5 MPa, 0.05 -0.3MPa may be sufficient. As the bonding rolls 5 and 5, the surface can use a conventionally well-known thing, such as a thing of metal (including alloys, such as SUS) and rubber | gum.

  In the step of bonding the polarizing plate 2 and the protect film 1, bonding is preferably performed while applying tension to the polarizing plate 2 and the protect film 1, and the tension before bonding of the polarizing plate 2 is the same as that of the protect film 1. It is more preferable that it is smaller than the tension before bonding. Such tension control is advantageous in increasing the MD positive curl of the obtained protective film-attached polarizing plate sheet. 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 5 and 5), 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 200 N / m or less from the viewpoint of increasing the MD positive curl of the protective film-attached polarizing plate sheet obtained. Is more preferred.
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) Cutting process S102
This step is a step of obtaining a protective film-attached polarizing plate sheet by cutting out from the region satisfying the formula (I) in the protective film-attached polarizing plate 3 obtained in the bonding step S101.
Cutting (cutting) can be performed using a conventionally known cutting means such as a cutting cutter.
As described above, “cut out the sheet from the area” means that the whole of the protect film of the cut sheet is included in the area.

The size, shape, and cutting angle of the cut out polarizing plate with a protective film are not particularly limited.
The protective film-attached polarizing plate sheet 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 protective film-attached polarizing plate 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.
In general, when the size of the protective film-attached polarizing plate increases, the MD positive curl tends to be less likely to occur. Therefore, when the size of the protective film-attached polarizing plate is large, it may be preferable to make the left side of the formula (I) larger in order to provide a sufficient MD positive curl amount.

Although there is no particular limitation, when the shape of the protective film-attached polarizing plate sheet is rectangular, when the protective film-attached polarizing plate sheet is viewed from the protect film side, the long side and the short side thereof It is possible to cut out a sheet of protective film-attached polarizing plate from the protective film-attached polarizing plate 3 so that the absorption axis direction (MD direction of the polarizing plate) of the polarizing plate forms an angle of 45 degrees.
Alternatively, when the shape of the protective film-attached polarizing plate is rectangular, when the protective film-attached polarizing plate is viewed from the protective film side, the absorption axis direction of the polarizing plate with respect to the long side (polarizer The protective film-attached polarizing plate sheet may be cut out from the protective film-attached polarizing plate 3 such that the MD direction of the (1) is parallel or at an angle of 90 degrees.

<Polarizer sheet with protect film>
The polarizing plate sheet with a protective film according to the present invention includes a polarizing plate and a protective film laminated on one side thereof, and the protective film has the following formula (II):
1st elastic modulus-2nd elastic modulus 300 300MPa (II)
Meet.
In the formula (II), the first elastic modulus is a tensile elastic modulus (MPa) in the 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 is It is a tensile elastic modulus (MPa) in the 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 protective film-attached polarizing plate sheet can have a sufficiently large MD positive curl.
According to the protective film-attached polarizing plate sheet having a sufficiently large MD positive curl, even if it is a case where another optical function layer or the like is laminated on the side of the polarizing plate to form the above-mentioned multilayer structure Since a state without a reverse curl (flat state) or a state with a positive curl can be maintained, the protective film-attached polarizing plate sheet or multilayer structure is pasted to the image display element through the pressure-sensitive adhesive layer. At the same time, it is possible to suppress problems such as sticking errors and air bubbles mixing in the interface between the pressure-sensitive adhesive layer and the image display element.

The protective film-attached polarizing plate sheet according to the present invention can be produced by the method for producing a protective film-attached polarizing sheet described above.
The direction perpendicular to the absorption axis of the polarizing plate has the same meaning as the TD direction of the protective film and the polarizing plate when the polarizing plate with polarizing plate is produced by the method for producing a polarizing plate with protective film described above. It is.

“To satisfy the formula (II)” means that, regardless of the position of the protective film, that is, the measurement sample is taken over the entire protective film, the first is measured according to the description of the example described later. It means that the elastic modulus and the second elastic modulus satisfy the formula (II).
For the same reason as described in the section <Method for producing protective film-attached polarizing plate sheet>, in the protective film-attached polarizing sheet, the formula (II) is applied over the entire direction orthogonal to the absorption axis of the polarizing plate. The protective film to be filled can usually be said to satisfy the formula (II) over the entire protective film (that is, regardless of the position of the protective film from which the measurement sample is taken).

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

  The size and shape of the protective film-carrying polarizing plate sheet are not particularly limited, and the specific size and shape are cited in the section of <Method of producing protective film-carrying polarizing plate sheet>. When the size of the protective film-attached polarizing plate sheet is large, it may be preferable to make the left side of the formula (II) larger in order to provide a sufficient amount of MD positive curl.

  The protective film-attached polarizing plate sheet (the same applies to the protective film-attached polarizing plate sheet obtained by the method for producing a protective film-attached polarizing plate according to the present invention) preferably exhibits MD positive curl, as described above. The amount of MD positive curl measured according to the description in the section of the examples described later is 40 mm or more so that the multilayer structure can still exhibit MD positive curl or flat state without curl. Is more preferred. The MD positive curl amount may be 45 mm or more. The MD positive curl amount is preferably 100 mm or less.

Although there is no particular limitation, when the shape of the protective film-attached polarizing plate sheet is rectangular, when the protective film-attached polarizing plate sheet is viewed from the protect film side, the long side and the short side thereof The absorption axis direction of the polarizing plate may form an angle of 45 degrees.
Alternatively, when the shape of the protective film-attached polarizing plate is rectangular, when the protective film-attached polarizing plate is viewed from the protective film side, the absorption axis direction of the polarizing plate is parallel to the long side of the sheet. It may be present or may form an angle of 90 degrees.

An example of the layer configuration of the protective film-attached polarizing plate sheet is shown in FIG. As shown in FIG. 5, when the protect film 1 is constituted by the base film 40 and the pressure-sensitive adhesive layer 50 laminated thereon, the pressure-sensitive adhesive layer 50 of the protect film 1 is the one side of the polarizing plate 2. It piles up so that it may touch.
About the more specific description of the polarizing plate 2 and the protect film 1, the description of the item of <a manufacturing method of a polarizing plate with a protect film> is cited.

<Polarizer with long protective film>
The long protective film-attached polarizing plate according to the present invention includes a long polarizing plate and a long protective film laminated on one side thereof, and the protective film has the following formula (III):
1st elastic modulus-2nd elastic modulus 300 300MPa (III)
Including the region that satisfies
In the formula (III), the first elastic modulus is a tensile elastic modulus (MPa) in a direction orthogonal to the absorption axis of a long polarizing plate at a temperature of 23 ° C. and a relative humidity of 55% RH, The ratio is a tensile elastic modulus (MPa) in a direction parallel to the absorption axis of a long polarizing plate at a temperature of 23 ° C. and a relative humidity of 55% RH.

According to the long protective film-attached polarizing plate including the above-mentioned region, by cutting out the sheet from the region, the cut-out sheet is provided with the protection film satisfying the formula (III). A large protective film-attached polarizing plate sheet can be obtained.
The above-mentioned "cut out the sheet from the area" means that the whole of the protect film of the cut sheet is included in the area.

The elongate protective film-attached polarizing plate according to the present invention can be produced by performing the bonding step S101 of the method of producing the protective film-attached polarizing plate described above.
The direction perpendicular to the absorption axis of the polarizing plate is the protection in the case of manufacturing a long protective film-attached polarizing plate by carrying out the bonding step S101 of the method for producing a protective film-attached polarizing plate described above. It is synonymous with the TD direction of a film and a polarizing plate.

The expression “satisfying the formula (III)” means that the first measurement is made according to the description of the example described later, regardless of the position of the protection film, that is, at any position of the protection film. It means that the elastic modulus and the second elastic modulus satisfy the formula (III).
For the same reason as described in the section <Method for producing protective film-attached polarizing plate sheet>, in the long protective film-attached polarizing plate, the formula (III) is applied over the entire direction orthogonal to the absorption axis of the polarizing plate. The protective film to be filled can usually be said to satisfy the formula (III) over the entire protective film (that is, regardless of the position of the protective film from which the measurement sample is taken).

  From the viewpoint of increasing the yield of the protective film-attached polarizing plate sheet, the above-mentioned region of the protective film preferably has an occupied area as large as possible, and the region is a protective film to be subjected to the bonding step S101. It is more preferable to extend at least the entire width direction, and it is further preferable to extend the entire protective film.

  The left side of Formula (III) is preferably 400 MPa or more, preferably 500 MPa or more, from the viewpoint of increasing the MD positive curl of the sheet with a protective film obtained by cutting it out from a polarizing plate with a long protective film. It is more preferable that The left side of the formula (III) is usually at most 2000 MPa, and typically at most 1500 MPa.

  The size, shape and cut-out angle of the protective film-attached polarizing plate are not particularly limited, and the specific size, shape and cut-out angle are described in the section <Method of producing protective film-attached polarizing sheet> Is quoted. When the size of the protective film-attached polarizing plate sheet obtained by cutting out from the long protective film-attached polarizing plate is large, the left side of the formula (III) is made larger to give a sufficient MD positive curl amount. It may be preferable to

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

  For a more specific description of the layer configuration of the long protective film-attached polarizing plate, the polarizing plate that constitutes the long protective film-attached polarizing plate, and the protective film, see <Method of producing a protective film-attached polarizing plate sheet> And the description in the section of <Protective film-attached polarizing plate sheet> is cited.

<Multilayer structure>
One or more optical function layers or separate films (release films) or the like are further added to the surface of the polarizing plate on the side of the polarizing plate with a protective film or a polarizing plate with a long protective film via a pressure-sensitive adhesive layer or an adhesive layer It may be stacked.
The optical functional layer may be a retardation layer or the like, and the optical functional layer can be laminated on the surface on the polarizing plate side via the pressure-sensitive adhesive layer or the adhesive layer.

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

  In the following experimental examples, the thicknesses of the polarizing plate and the film, the elastic modulus difference of the protective film, the tension before bonding in the MD direction of the polarizing plate and the protective film, and the MD curling amount of the polarizing plate with protective film are as follows: It measured according to.

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

(2) Difference in Elastic Modulus of Protecting Film A rectangular piece with a long side of 100 mm and a short side of 25 mm was cut out from a long polarizing plate with a protect film using a super cutter. The cutting was performed so that the long side of the small piece was parallel to the MD direction of the polarizing plate with a long protective film, and the short side of the small piece was parallel to the TD direction of the polarizing plate with a long protective film. The polarizing plate was peeled off from this small piece, and the small piece of the obtained protective film alone was used as a sample for measurement of the MD 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 protective film-attached polarizing plate using a supercutter. However, the cutting was performed so that the long side of the small piece was parallel to the TD direction of the polarizing plate with a long protective film, and the short side of the small piece was parallel to the MD direction of the polarizing plate with a long protective film. . The polarizing plate was peeled off from this small piece, and the small piece of the single protective film thus obtained was used as a sample for measuring the TD elastic modulus.

Then, with the upper and lower grips of a tensile tester [Autograph AG-Xplus testing machine manufactured by Shimadzu Corporation], pinch both ends in the long side direction of the measurement sample so that the distance between the grips is 5 cm, 23 ° C The tensile strength is 1 mm / min in an environment of 55% relative humidity, and the measurement sample is pulled in the length direction of the measurement sample, and the slope of the straight line between 3 and 6 MPa in the obtained stress-strain curve is 23 ° C. relative The tensile elastic modulus [MPa] at a humidity of 55% was calculated. 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 sample for measurement of the MD elastic modulus is the MD elastic modulus, and the tensile elastic modulus calculated from the measurement of the sample for the measurement of the TD elastic modulus is the TD elastic modulus.

In each of the following experimental examples, both films are pasted together so that the absorption axis (MD direction) of the polarizing plate is parallel to the MD direction of the protecting film, so that the polarizing plate with a protective film is manufactured. The TD elastic modulus in the formula (I) is synonymous with the first elastic modulus in the above formula (II) and the formula (III), and the MD elastic modulus in the above formula (I) is the above formula (II) and the formula (III) And the second elastic modulus in the above.
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".

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, TD elastic modulus-MD elastic modulus (first elastic modulus-second elastic modulus) will be 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.

(4) MD curling amount of the protective film-attached polarizing plate sheet As shown in FIG. 6, the absorption axis 61 of the polarizing plate when viewed from the protective film side from the obtained long protective film-attached polarizing plate 60. Using a supercutter, cut out a small piece (sheet-like body) of rectangular shape (long side 140 mm × short side 70 mm) so that the length is 45 degrees with respect to the long side and short side, and use this for measuring the MD curl amount It was set as sample 70. The cutting out of the measurement sample 70 was performed under an environment of 23 ° C. and a relative humidity of 55% immediately after bonding the polarizing plate and the protect film.
The measurement sample 70 was placed on the reference surface (horizontal base) with the concave side up. In this state, of the two diagonal lines of the measurement sample 70, the height from the reference plane is measured for each of the two diagonal lines 80 on the smaller diagonal line of the measurement sample 70 relative 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.
The state in which the protective film side is concave is the state in which the positive curl is provided, and the state in which the polarizing plate side is concave is the state in which the reverse curl is provided. In Experimental Examples 1 to 3 below, any of the measurement samples (sheets with a protective film) had a positive curl.

Experimental Examples 1 to 3
(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.

  Experimental Examples 1 to 3 The manufacturing method of the elongated protective film-attached polarizing plate is the same except that the used protective film is different (the product is the same but the lot is different). Hereinafter, the protect films used in Experimental Examples 1 to 3 are also referred to as Protect films 1 to 3, respectively.

From the obtained polarizing plate with a long protective film, the TD elastic modulus and the MD elastic modulus, and the elastic modulus difference were determined according to the method described above.
Each of the protect films 1 to 3 has a width (length in the TD direction) of 1300 mm. When measuring the modulus of elasticity of each protect film, a total of seven positions of 100 mm, 280 mm, 470 mm, 650 mm, 830 mm, 1020 mm and 1200 mm from one end in the width direction along one width direction at one arbitrary MD direction position The sample for measurement was cut out by this, and the TD elastic modulus, the MD elastic modulus, and the elastic modulus difference were calculated | required about each of these seven samples for measurement. These results are shown in the column "1" of Table 1. Seven measurement samples are cut out at a position separated by 20 mm from one arbitrary MD direction position along the MD direction in the same manner as above, and TD elastic modulus and MD elasticity are obtained for each of these seven measurement samples. The modulus and modulus differences were determined. These results are shown in the column "2" of Table 1. Seven measurement samples are cut out at a position 50 mm apart from one arbitrary MD direction position along the MD direction as described above, and TD elastic modulus and MD elasticity are obtained for each of these seven measurement samples. The modulus and modulus differences were determined. These results are shown in the column "3" of Table 1.
Moreover, the graph which shows the relationship between the width direction position of the protective films 1-3, and an elastic modulus difference (elastic modulus described in the column of "1" of Table 1) is shown in FIG.
With regard to the position where the measurement sample is cut out, for example, “cut out the measurement sample at a position 100 mm from one end in the width direction” means that the position 100 mm from the one end in the width direction matches the center position in the width direction of the measurement sample. Means to cut out the sample for measurement. The same applies to the position from one end in the other width direction.

As shown in Table 1 and FIG. 7, the long protective films 1 and 2 cover the whole, that is, the entire TD direction (the direction orthogonal to the absorption axis of the long polarizing plate), and the entire MD direction ( It can be seen that the region including the region satisfying the formulas (I) and (III) is included over the absorption axis direction of the long polarizing plate, and this region covers the entire width direction of the protect film.
On the other hand, the long protect film 3 covers the entire TD direction (the direction orthogonal to the absorption axis of the long polarizing plate) and the entire MD direction (the absorption axis direction of the long polarizing plate) Although the area | region which satisfy | fills Formula (I) and (III) over is included, this area | region is not over the width direction of a protection film. That is, the long protective film 3 satisfies the formulas (I) and (III) only in the region from the one end in the width direction to about 700 mm from the one end.
As described above, the protective film satisfying the formulas (I) and (III) at one arbitrary MD direction position usually satisfies the formulas (I) and (III) also at other MD direction positions.

(D) Preparation of Polarizing Sheet with Protecting Film As shown in FIG. 6, the absorption of the polarizing plate as viewed from the protecting film side from the polarizing plate with a long protective film obtained in (C) above. Using a supercutter, cut out a small piece (sheet) of a rectangle (long side 140 mm × short side 70 mm) so that the axis is 45 degrees to the long side and short side, I got a body.

The amount of MD curl of the obtained protective film-attached polarizing plate sheet was measured according to the method described above.
Experimental Examples 1 to 3 The long protective film-carrying polarizing plates each have a width of 1330 mm (length in the TD direction). In the measurement of the MD curling amount of the protective film-attached polarizing plate sheet obtained from each long protective film-attached polarizing plate, from one end in the width direction along the width direction at one arbitrary MD-direction position The protective film-attached polarizing plate sheet was cut out at a total of seven positions of 100 mm, 280 mm, 470 mm, 650 mm, 830 mm, 1020 mm and 1200 mm, and the MD curl amount was measured for each of these seven sheets. Seven individual sheets were cut out from the vicinity of the cut-out position of the measurement sample for measuring the difference in elastic modulus of the protect film described in the column "1" of Table 1. The results are shown in Table 2. Moreover, the relationship between the width direction position which cuts out a sheet with protective film with a protective film from the long polarizing film with a protective film in experimental examples 1 to 3 and the MD curl amount of the sheet with a protective film with a cut out Is shown in FIG.
With regard to the position where the protective film-attached polarizing plate sheet is cut out, for example, “cut out the protective film-attached polarizing plate sheet at a position of 100 mm from one end in the width direction” means that the position of 100 mm from the one end in the width direction It means that the polarizing plate sheet with a protective film is cut out so that the center position in the width direction of the polarizing plate sheet coincides. The same applies to the position from one end in the other width direction.
Experimental Examples 1 to 3 Each of the protective film-attached polarizing plate sheets cut out from the long protective film-attached polarizing plate had a positive curl. Therefore, the measured amount of MD curl is the amount of MD positive curl.

Experimental Example 1 Using Protecting Film 1 Seven Protecting Film Attached Polarizing Plate Sheets Cut Out from a Long Protecting Film Attached Polarizing Plate, and Experimental Example 2 Using Protecting Film 2 In the seven sheets of the polarizing plate with protective film cut out from the polarizing plate, the protective film laminated on the polarizing plate satisfies the formula (II).
Of the seven sheets of the polarizing plate with the protective film cut out from the long polarizing plate with the protective film in the experimental example 3 using the protective film 3, from one end in the width direction of the polarizing plate with the long protective film The sheet cut out at the positions of 100 mm, 280 mm, 470 mm and 650 mm satisfies the formula (II) for the protect film laminated on the polarizing plate, but the sheet cut out at the positions of 830 mm, 1020 mm and 1200 mm The body does not meet this.

  As shown in Table 2 and FIG. 8, the polarizing plate sheet with a protective film satisfying the formula (II) exhibited an MD positive curl amount of 40 mm or more. On the other hand, the sheet with a protective film with a protective film not satisfying the formula (II) had an MD positive curl amount smaller than 40 mm.

  Reference Signs List 1 protect film, 2, 2a, 2b polarizer, 3 polarizer with protect film, 5 bonding roll, 10 polarizer, 20 first thermoplastic resin film, 30 second thermoplastic resin film, 40 substrate film, 50 Pressure-sensitive adhesive layer, polarizing plate with long protective film, 60 absorption axis of polarizing plate, sample for measurement of 70 MD curl amount, angle of sample for measurement of 80 samples.

Claims (11)

Bonding a protective film including a region satisfying the following formula (I) on one side of a polarizing plate to obtain a polarizing plate with a protective film;
Cutting out a sheet of the polarizing plate with a protective film from the area;
The manufacturing method of the polarizing plate sheet material body with a protective film containing.
TD elastic modulus-MD elastic modulus 300 300MPa (I)
[In the formula, TD elastic modulus is a tensile elastic modulus in the TD direction at a temperature of 23 ° C. and a relative humidity of 55% RH, and MD elastic modulus is in the MD direction at a temperature of 23 ° C. and a relative humidity of 55% RH. It is a tensile elastic modulus. ]   The manufacturing method according to claim 1, wherein the polarizing plate and the protective film are sandwiched between a pair of rolls and pasted.   The manufacturing method according to claim 2, wherein the polarizing plate is long and the protect film is long. The tension before bonding of the polarizing plate is 200 N / m or less,
The manufacturing method according to claim 3, wherein the tension before bonding of the protective film is 300 N / m or more.   The manufacturing method according to any one of claims 1 to 4 pasted so that an absorption axis of said polarizing plate and MD direction of said protection film may become parallel.   The thickness of the said polarizing plate is 70 micrometers or less, The manufacturing method of any one of Claims 1-5. A polarizing plate and a protective film laminated on one side of the polarizing plate,
The polarizing plate sheet having a protective film, wherein the protective film satisfies the following formula (II).
1st elastic modulus-2nd elastic modulus 300 300MPa (II)
[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. ]   8. The sheet according to claim 7, wherein the amount of curling in a direction parallel to the absorption axis of the polarizing plate having a convex surface on the polarizing plate side is 40 mm or more.   The thickness of the said polarizing plate is 70 micrometers or less, The polarizing plate sheet material with a protective film of Claim 7 or 8. A long polarizing plate and a long protective film laminated on one side of the long polarizing plate;
A long polarizing plate with a protective film, wherein the protective film comprises a region satisfying the following formula (III).
1st elastic modulus-2nd elastic modulus 300 300MPa (III)
[Wherein, the first elastic modulus is a tensile elastic modulus 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, and the second elastic modulus is It is a tensile elastic modulus 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 long protective film with polarizing plate according to claim 10, wherein the region covers the entire width direction of the protective film.