KR102510750B1 - Polarizing plate with protective film, and liquid crystal panel - Google Patents

Abstract

[Problem] To provide a polarizing plate with a protection film capable of reducing the force required for standing the protection film at the time of peeling the protection film.
[Solution] At least one cross section in the lamination direction is at an outermost position (P1) of the polarizing film with respect to a direction orthogonal to the lamination direction at at least one end portion of the direction orthogonal to the lamination direction. And the outermost position (P2) of the optical film is the following (i) to (iii):
(i) position P1 is outside position P2;
(ii) position P1 and position P2 are the same;
(iii) the position P1 is inside the position P2 and the distance between the positions P1 and P2 is 1 μm or less;
A polarizing plate with a protection film that satisfies any one of these relationships.

Description

Polarizing plate and liquid crystal panel with protective film {POLARIZING PLATE WITH PROTECTIVE FILM, AND LIQUID CRYSTAL PANEL}

The present invention relates to a polarizing plate with a protection film and a liquid crystal panel.

A polarizing plate is widely used as a polarized light supplying element and a polarized light detecting element in a display device such as a liquid crystal display device. As a polarizing plate, it is common to have a structure in which a protective film is bonded to one side or both sides of a polarizer using an adhesive.

On the surface of the polarizing plate, in order to protect the surface during storage or in the manufacturing process constituting the liquid crystal panel, for example, as described in Patent Document 1, a peelable protection film (also called a peeling film or a surface protection film) is bonded. It may be used as a polarizing plate with a protection film. The protective film is peeled off after bonding the polarizing plate to the liquid crystal cell.

Patent Document 1: Japanese Unexamined Patent Publication No. 2016-170383

Peeling of the protective film is performed by applying force in a direction perpendicular to the film surface to an end portion of the protective film to stand up (peeling start), and then, a force in the direction of the film surface is applied to the raised portion to separate from the polarizing plate. The application of force to the protection film at the time of peeling may be performed by holding the edge of the protection film, or may be performed by holding a peeling tape attached to the surface of the protection film through this.

The force for raising the protective film (hereinafter also referred to as "standing force") and the force for peeling in the plane direction after raising the protection film (hereinafter also referred to as "in-plane peeling force") are the pressure-sensitive adhesive for adhering the protection film to the polarizing plate. Although it can reduce by making adhesive force weak, the problem of a protection film lifting or peeling at an unintended timing may be caused. Normally, the standing force is larger than the in-plane peeling force.

A polarizing plate with a protection film WHEREIN: Excessive force is required for standing up of a protection film, and peeling of a protection film may become difficult. As a general configuration of a polarizing plate, there is a configuration in which an optical film is bonded on a polarizing film through an adhesive. Also in the polarizing plate with a protection film which consists of a polarizing plate of such a structure, excessive force is required for standing up of a protection film, and peeling of a protection film may become difficult.

An object of this invention is to provide the polarizing plate with a protection film which can reduce the force required for standing up a protection film at the time of peeling of a protection film.

This invention provides the manufacturing method of the polarizing plate with a protection film shown below, a liquid crystal panel, and the polarizing plate with a protection film.

[1] A polarizing plate having a polarizing film and an optical film;

A protective film laminated on the surface of the polarizing plate,

A polarizing plate with a protection film in which the polarizing film, the optical film, and the protection film are laminated in this order,

At least one cross section in the lamination direction is located at the outermost position P1 of the polarizing film and the optical film in a direction orthogonal to the lamination direction at at least one end of the direction orthogonal to the lamination direction. The outermost position (P2) of (i) to (iii):

(i) position P1 is outside position P2;

(ii) position P1 and position P2 are the same;

(iii) the position P1 is inside the position P2 and the distance between the positions P1 and P2 is 1 μm or less;

A polarizing plate with a protection film that satisfies any one of these relationships.

[2] The polarizing plate with a protection film according to [1], wherein the polarizing film is provided with a polarizer and a protective film.

[3] The polarizing plate further has a pressure-sensitive adhesive layer,

The polarizing plate with a protection film according to [1] or [2], wherein the polarizing film, the pressure-sensitive adhesive layer, the optical film, and the protection film are laminated in this order.

[4] The polarizing plate with a protection film according to any one of [1] to [3], wherein the end portion exists on a polished end face.

[5] The polarizing plate with a protection film according to [4], wherein the polishing end face has a shape in which V-shaped grooves and pointed portions are alternately formed.

[6] The polarizing plate with a protection film described in [4] or [5], wherein the position (P1) and position (P2) satisfy the relationship of (i) above.

[7] Equipped with a liquid crystal cell and a polarizing plate with a protective film described in [3],

A liquid crystal panel in which the liquid crystal cell, the polarizing film, the pressure-sensitive adhesive layer, the optical film, and the protection film are laminated in this order.

[8] A step of obtaining a film laminate in which a polarizing film, an optical film, and a protection film are laminated in this order;

At least one end face of the film laminate is polished, and at the end face, in a direction orthogonal to the lamination direction, the outermost position P1 of the polarizing film and the outermost side of the optical film The position (P2) of (i) to (iii):

(i) position P1 is outside position P2;

(ii) position P1 and position P2 are the same;

(iii) the position P1 is inside the position P2 and the distance between the positions P1 and P2 is 1 μm or less;

The manufacturing method of the polarizing plate with a protection film which has the process which makes it satisfy any relationship among them.

ADVANTAGE OF THE INVENTION According to the polarizing plate with a protection film of this invention, the force required for standing up a protection film can be reduced at the time of peeling of a protection film.

1 is a sectional view in the stacking direction showing an example of a polarizing plate with a protection film according to the present invention (Example 3).
Fig. 2 is a cross-sectional view in the stacking direction showing an example of a polarizing plate with a protection film according to the present invention.
Fig. 3 is a cross-sectional view in the stacking direction showing an example of a polarizing plate with a protection film according to the present invention (Example 1).
Fig. 4 is a cross-sectional view in the stacking direction showing an example of a polarizing plate with a protection film according to the present invention (Example 2).
5 is a cross-sectional view showing an example of the layer structure of the polarizing plate with a protection film according to the present invention.
Fig. 6 is a cross-sectional view showing an example of the layer structure of the polarizing plate with a protection film according to the present invention.
Fig. 7 is a schematic perspective view of an end surface processing apparatus using an end surface of a polarizing plate laminate for polishing.
8 is a schematic view showing a peeling method of a protection film.
Fig. 9 is a schematic view showing an example of a direction in which a release tape is attached.
Fig. 10 is a schematic view showing an example of a direction in which a release tape is attached.
11 is a schematic view showing a peeling angle.
12 is a cross-sectional view of a polarizing plate with a protection film of Comparative Example 1 in the lamination direction.
13 is a cross-sectional view of a polarizing plate with a protection film of Comparative Example 2 in the lamination direction.
14 is a cross-sectional view of a polarizing plate with a protection film of Comparative Example 3 in the lamination direction.
15 is a schematic diagram showing the method of evaluation test 1.
Fig. 16 is a top perspective view showing a rectangular polarizing plate with a protective film.

<Polarizing plate with protective film>

(1) Configuration of polarizing plate with protective film

A polarizing plate with a protection film according to the present invention includes a polarizing plate having a polarizing film (A) and an optical film (C), and a protection film (D) laminated on the surface of the polarizing plate, and comprising: a polarizing film (A), an optical film A film (C) and a protection film (D) are laminated in this order. In the polarizing plate, the optical film (C) is bonded and laminated with, for example, an adhesive layer (B). In this case, the polarizing plate with a protective film includes a polarizing film (A), an adhesive layer (B), an optical film (C), The protection film (D) is laminated in this order.

An example of the layer configuration of the polarizing plate with a protection film according to the present invention will be described with reference to FIG. 1 .

1 shows a cross-sectional view of a polarizing plate with a protection film in the lamination direction. As shown in FIG. 1 , the polarizing plate 111 with a protection film includes a separate film 70, a first pressure sensitive adhesive layer 31, a protective film 22, and a polarizer 10 (protective film 22). and the laminated film 20 composed of the polarizer 10 is equivalent to the polarizing film (A), the third adhesive layer 32 (corresponds to the adhesive layer (B)), and the brightness enhancement film 50 (optical The polarizing plate 100 including the film (corresponding to C) laminated in the above order, and the protective film 60 (protective film D ) equivalent to) is provided. The protection film 60 is composed of a base film 61 and a second pressure sensitive adhesive layer 62 laminated thereon, and is bonded and laminated to the polarizing plate 100 via the second pressure sensitive adhesive layer 62 .

At least one end surface in the lamination direction of the polarizing plate with a protection film of the present invention is at least one end of the direction orthogonal to the lamination direction, with respect to the direction orthogonal to the lamination direction, the outermost side of the polarizing film (A). Position P1 (hereinafter, such a position may be simply referred to as “position P1”) and the outermost position P2 of the optical film C (hereinafter, such a position is simply referred to as “position P2”). (sometimes referred to as) are the following (i) to (iii):

(i) position P1 is outside position P2;

(ii) position P1 and position P2 are the same;

(iii) the position P1 is inside the position P2 and the distance L between the positions P1 and P2 is 1 μm or less;

Which of these relationships are satisfied? The end portion shown in Fig. 1 of the polarizing plate 111 with a protection film satisfies the above relationship (iii).

If the relationship between the position P1 and the position P2 satisfies any of the above relationships (i) to (iii), the reference point is a position inside the position P2 and at a distance of 1 μm from the position P2. In one case, the position P1 is meant to be located outside the reference point.

[0082] The above characteristics of the position (P1) and position (P2) of the polarizing plate with a protective film of the present invention will be described more concretely with reference to FIG. A polarizing plate with a protection film is normally rectangular. Fig. 16 is a top perspective view schematically showing a rectangular polarizing plate with a protective film. The quadrangular polarizing plate 110 with a protective film has four end surfaces 110a, 110b, 110c, and 110d on the side surface ("end surface" in this specification means the end surface on the side surface unless otherwise specified). . In the polarizing plate 110 with a protection film of the present invention, at least one end face in the stacking direction (direction of the arrow) (e.g., end faces 115 and 116 passing through two opposing end faces), preferably a long polarizing plate with a protection film The cross section parallel to the side or short side) is at least one end in the direction orthogonal to the stacking direction (direction of the arrow) (e.g., in the case of end face 115, end 115b or end 115d, end face 116) In the case of the end portion 116a or the end portion 116c), in a direction orthogonal to the stacking direction, the position P1 and the position P2 are configured to satisfy any of the above relationships (i) to (iii). has been The ends described above (eg, ends 115b, 115d, 116a, and 116c) are present on any of the end faces 110a, 110b, 110c, and 110d.

The polarizing plate with a protection film of the present invention has an end that satisfies any of the above relationships (i) to (iii), and by starting peeling of the protection film from this end, the force required for standing the protection film can be reduced. there is. In the polarizing plate with a protection film, it is preferable to have an end face that satisfies any one of the above relationships (i) to (iii) in the entire region. In this case, even when peeling of the protection film is started from any end of such an end face, the force required for standing the protection film can be reduced. In addition, in the polarizing plate with a protection film, it is more preferable that any one of the above relationships (i) to (iii) is satisfied in all four end faces in all regions. In this case, even when peeling of the protection film is started from any end, the force required for standing the protection film can be reduced.

In the end portion shown in Fig. 1 of the polarizing plate 111 with a protection film, the distance L between the position P1 and the position P2 is 1 µm or less, and the above relation (iii) is satisfied. It is assumed that the positional relationship of the position P1 and the position P2 of the polarizing plate 111 with a protection film is the same as that shown in FIG. 1 with respect to all ends. In the polarizing plate 111 with a protection film, the end positions of the polarizing film (A) and the optical film (C) are adjusted so as to satisfy the relationship (iii) above.

2 is a cross-sectional view showing another example of a polarizing plate with a protection film. As for the edge part shown in FIG. 2 of the polarizing plate 112 with a protection film, the position P1 is outside the position P2, and the relationship of said (i) is satisfied. The polarizing plate 112 with a protection film assumes that the positional relationship of the position P1 and the position P2 is the same as the relation shown in FIG. 2 at all ends. In the polarizing plate 112 with a protection film, the end positions of the polarizing film (A) and the optical film (C) are adjusted so as to satisfy the relationship (i) above.

1 and 2 specifically show the layer configuration of the polarizing plate with a protection film and the positional relationship between positions P1 and P2. Therefore, in the example shown in FIG. 1 or 2, if the positional relationship between the layer structure of the polarizing plate with a protection film and the position P1 and the position P2 satisfies the relationship shown in FIG. 1 or 2, each Embodiments in which other conditions such as the relative thickness of the layers and the relative width of each layer are different from those shown in FIG. 1 or FIG. 2 are also included. As shown in FIGS. 1 and 2, a protective film in which a polarizing laminated film (A) and an optical film (C) are laminated via an adhesive layer (the third adhesive layer 32 in FIGS. 1 and 2) is attached. In a polarizing plate, since the modulus of elasticity of the pressure-sensitive adhesive layer is lower than that of the protection film, the pressure-sensitive adhesive layer tends to absorb the force of raising the protection film, and a large force may be required to raise the protection film. In particular, when the storage modulus of the pressure-sensitive adhesive layer interposed between the polarizing laminated film (A) and the optical film (C) is 0.1 MPa or less, and furthermore 0.08 MPa or less at a temperature of 20°C, the protective film is protected by this pressure-sensitive adhesive layer. By absorption of the force for standing up, a large force may be required to stand up the protection film. According to the present invention, even in a polarizing plate with a protection film in which an adhesive layer having a storage modulus of 0.1 MPa or less at a temperature of 20 ° C. is interposed between the polarizing laminated film (A) and the optical film (C), the protection film is lifted up. The force required can be reduced. Moreover, the storage elastic modulus in the temperature of 20 degreeC of the adhesive layer interposed between the polarizing laminated film (A) and the optical film (C) is 0.01 MPa or more normally.

The storage modulus of the pressure-sensitive adhesive layer can be measured using a commercially available rheometer. Specifically, MCR301 manufactured by Anton Paar can be used. Measurement conditions can be as follows. In addition, the storage elastic modulus shown in this specification is a value measured using the apparatus and measurement conditions described here.

Measuring jig: 25 mm diameter parallel plate

Temperature: 20℃

Frequency: 1Hz

Variation: 1%

Normal Force: 0 N

Sample shape: What laminated the adhesive layer so that it might become 210 micrometers

Regarding the polarizing plate with a protective film, the end positions of the polarizing film (A) and the optical film (C) may be adjusted during lamination, or after lamination, cutting, polishing, etc. may be performed by end face processing. When end face processing is performed on a polarizing plate with a protection film, a larger force may be required in order to make the protection film stand up. As one of these factors, it is conceivable that the cross-sectional shape of the protection film is changed by the end surface processing, so that force dispersion is likely to occur. ADVANTAGE OF THE INVENTION According to this invention, also in the polarizing plate with a protection film in which the end surface processing is given, the force required for lifting up a protection film can be reduced. After lamination, the polarizing plate with a protection film may be cut into a shape such as a rectangle and a predetermined dimension shape according to a liquid crystal cell. Moreover, in order to improve the dimensional accuracy of a polarizing plate and make an end surface smooth, there are cases where the end surface is polished. If the end face is polished, it is likely that the end face will not be flush. The end surface processing of the polarizing plate with a protection film is normally performed in a state in which a plurality of polarizing plates are stacked and pressed from the top and bottom to be fixed. In this case, each layer constituting the polarizing plate is temporarily deformed (thinned and widened) by pressing force from the top and bottom, and end faces are processed in the deformed state. The degree of deformation differs depending on the magnitude of the pressing force from the top and bottom, the layer structure and size of the polarizing plate, the thickness of each layer, and the like. Therefore, the end face shape at the time of end face processing is different from the end face shape in a state in which the deformation returns to the original state by releasing the pressing force from the top and bottom.

3 and 4 are sectional views showing an example of a polarizing plate with a protection film according to the present invention to which such an end surface processing has been performed. 3 and 4 differ in whether the angle of the end face with respect to the surface of the protection film 60 is an obtuse angle (FIG. 3) or an acute angle (FIG. 4). 3 and 4 specifically show the layer structure of the polarizing plate with a protection film and the positional relationship between positions P1 and P2. Therefore, in the example shown in FIG. 3 or 4, if the positional relationship between the layer configuration of the polarizing plate with a protection film and the position P1 and the position P2 satisfies the relationship shown in FIG. 3 or 4, each Embodiments in which other conditions such as the relative thickness of the layers and the relative width of each layer differ from those shown in FIG. 3 or FIG. 4 are also included. The polarizing plates 113 and 114 with a protection film assume that the positional relationship of the position P1 and the position P2 is the same as the positional relation shown in FIG. 3 or FIG. 4 at all ends.

The end surfaces of the polarizing plates 113 and 114 with protective films shown in FIGS. 3 and 4 have a shape in which V-shaped grooves and pointed portions are formed alternately (hereinafter, such a shape is also referred to as a “zigzag shape”). do. The polarizing plates 113 and 114 with a protection film are produced by polishing four end faces in a state in which they are pressed and fixed from the top and bottom. The end face to which the pressing force is released after being polished to be substantially flush in a state deformed by pressing from above and below (hereinafter also referred to as "polished end face") It may become a shape in which upper parts are formed alternately. The polished end face is distinguished from the end face without polish marks in that it has polish marks. A polarizing plate with a protection film subjected to such end surface polishing can realize high dimensional accuracy.

Since the pressure-sensitive adhesive layer tends to have higher viscoelasticity than the adjoining layer, and the degree of deformation due to pressing from above and below tends to be large, when the pressing force is released after polishing, the cross section tends to form a V-shaped groove. The V-shaped groove is formed at a position where the degree of polishing is greater than that of the surrounding area. On the other hand, since a layer with low viscoelasticity tends to have a small degree of deformation due to pressing from above and below, when the pressing force is released after polishing, the cross section tends to be pointed. The pointed portion is formed at a position where the degree of polishing is small compared to the surroundings. The formation position of the V-groove and the tip, the depth of each V-groove, and the height of each tip can be appropriately adjusted by adjusting the material and thickness of each layer, pressing force from above and below, and the like. Polarizing plates 113 and 114 with protective films shown in Figs. 3 and 4 have their end surfaces polished so as to satisfy the above relationship (i).

In the polarizing plate with a protection film according to the present invention, at the time of peeling the protection film (usually, the relationship at the time of bonding to the liquid crystal cell is maintained), an end portion satisfying any of the above relationships (i) to (iii) have Particularly, when the end face has a zigzag shape as shown in Figs. 3 and 4, it is preferable to have an end that satisfies the above relationship (i). By making the edge of this end face the position where peeling of a protection film starts, the force required in order to stand up a protection film can be reduced more.

Conventionally, when the position at which peeling starts is provided on a zigzag end surface that is a polished end surface, excessive force may be required to lift up the protective film. It is expected that this is due to the fact that the force applied at the time of peeling the protection film does not act as a force to effectively lift the protection film. Even in such a case, the force required for lifting the protection film can be further reduced by having an end portion that satisfies the relationship of the above (i) and lifting the protection film from this end portion. When the above relationship (i) is satisfied, the distance L between the positions P1 and P2 in the width direction is preferably 20 μm or less, more preferably 1 μm or more and 10 μm or less, and 2 μm It is more preferable that it is more than 8 micrometers. When the pressure-sensitive adhesive layer (B) is provided between the polarizing film (A) and the optical film (C), since a V-groove tends to be easily formed at the position of the pressure-sensitive adhesive layer (B), the polarizing film (A) It tends to be an end face having a V-groove between the and the optical film (C). In addition, the size of the polarizing plate is not limited, but it is, for example, a rectangular shape with a side length of 5 to 30 cm.

The distance L of the width direction of the position P1 and the position P2 can be measured using the laser microscope which can observe a three-dimensional surface shape, for example. Specifically, the distance L can be measured in a non-contact manner by scanning the end surface shape of the polarizing plate with a protection film with a 20-fold or 50-fold objective lens with a laser. As a laser microscope, Olympus Corporation LEXT (registered trademark) OLS4100 is mentioned.

3 and 4 show a case in which the deepest part of the V-groove and the top of the tip are straight as an example in which the polishing end surface is in a zigzag shape, but the zigzag shape is not limited to this, and the V-shaped The connection between the deepest part of the groove and the top of the spire may be a curved line or a combination of a curved line and a straight line. Further, in a zigzag shape, the deepest portion of the V-shaped groove and the top portion of the pointed portion may be rounded.

The layer structure of the polarizing plate with a protection film is not limited to the example shown in FIGS. 1-4. In FIGS. 5 and 6, layer configurations different from those shown in FIGS. 1 to 4 are illustrated. In FIGS. 5 and 6, the cross-sectional shape of the end face of the polarizing plate with a protection film is omitted and shown as a straight line, but the above description based on FIGS. 1 to 4 is cited.

The polarizing plate with a protection film shown in FIG. 5 includes a separate film 70, a first pressure sensitive adhesive layer 31, a protective film 22, a polarizer 10, and a protective film 21 (protective film 22 ), the polarizer 10, and the protective film 21, the laminated film 20 is equivalent to the polarizing film (A), the third adhesive layer 32 (corresponds to the adhesive layer (B)), and the luminance The polarizing plate 100 including the enhancement film 50 (corresponding to the optical film (C)) laminated in the above order, and the protective film 60 (protective film (D)) laminated on the surface of the polarizing plate 100 Equivalent to) is provided.

The polarizing plate included in the polarizing plate with a protective film shown in FIG. 6 does not have the protective film 22 and is directly laminated on the surface of the polarizer 10 with the first pressure sensitive adhesive layer 31 shown in FIG. 5. It has the same layer configuration as the polarizing plate. In the polarizing plate with a protection film shown in FIG. 6 , the laminated film 20 composed of the polarizer 10 and the protective film 21 corresponds to the polarizing film (A).

Although illustration is abbreviate|omitted in FIGS. 1-6, in the polarizing film 20, bonding of the polarizer 10 and the protective films 21 and 22 can be performed using an adhesive agent. In this specification, the adhesive layer made of an adhesive is also regarded as a component of the polarizing film 20 .

(2) protective film (D)

The protection film 60 is composed of a base film 61 and a second pressure-sensitive adhesive layer 62 laminated thereon. The protection film 60 is a film for protecting the surface of the polarizing plate 100, for example, after the polarizing plate with the protection film is bonded to an image display element such as a liquid crystal cell or other optical member, the second pressure sensitive adhesive layer 62 it has Each exfoliation is removed. The thickness of the protection film is, for example, 30 to 100 μm.

The resin constituting the base film 61 is, for example, a thermoplastic resin such as a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate, and a polycarbonate-based resin. can be Preferably, they are polyester-based resins, such as polyethylene terephthalate. The base film 61 may have a single layer structure or a multilayer structure, but from the viewpoints of ease of manufacture and manufacturing cost, etc., it is preferably a single layer structure. The base film 61 may be either a uniaxially stretched film or a biaxially stretched film, but is preferably a biaxially stretched film from the viewpoints of mechanical strength of the film, ease of manufacture, manufacturing cost, and the like.

Regarding the second pressure sensitive adhesive layer 62, descriptions relating to the first pressure sensitive adhesive layer 31 and the third pressure sensitive adhesive layer 32 described later are cited.

(3) Polarizer

The polarizer 10 is an absorption type polarizer having a property of absorbing linearly polarized light having a vibration plane parallel to the absorption axis and transmitting linearly polarized light having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis), A polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film can be suitably used. The polarizer 10 includes, for example, a step of uniaxially stretching a polyvinyl alcohol-based resin film; a step of adsorbing the dichroic dye by dyeing the polyvinyl alcohol-based resin film with the dichroic dye; A step of treating the polyvinyl alcohol-based resin film to which the dichroic dye is adsorbed with an aqueous solution of boric acid; And it can manufacture by the method including the process of washing with water after treatment by boric acid aqueous solution.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate and other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The average polymerization degree of polyvinyl alcohol-type resin is 1000-10000 normally, and 1500-5000 are preferable. The average degree of polymerization of polyvinyl alcohol-based resin can be determined in accordance with JIS K 6726.

What produced such a polyvinyl alcohol-type resin into a film is used as a raw film of the polarizer 10 (polarizing film). The method for forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a known method is employed. The thickness of the polyvinyl alcohol-based raw film is not particularly limited, but in order to make the thickness of the polarizer 10 15 μm or less, a film of 5 to 35 μm is usually used, and preferably 20 μm or less. In order to obtain a polarizer 10 having a thickness of 15 μm or less by stretching a polyvinyl alcohol-based raw film having a thickness of more than 35 μm, it is necessary to increase the stretching ratio, and even when the thickness of the polarizer 10 is 15 μm or less Dimensional shrinkage under a high temperature environment becomes large. In addition, when the thickness is less than 5 μm, the handleability at the time of stretching is reduced, and it becomes easy to cause problems such as cutting at the time of polarizer production.

Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may perform uniaxial stretching in these several steps.

In uniaxial stretching, uniaxial stretching may be performed between rolls having different circumferential speeds, or uniaxial stretching may be performed using a hot roll. Further, 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 where the polyvinyl alcohol-based 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 the dichroic dye is employed. As the dichroic dye, iodine or a dichroic organic dye is used. In addition, it is preferable to perform the immersion process to water before a dyeing process of a polyvinyl alcohol-type resin film.

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

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

The polyvinyl alcohol-based resin film after the boric acid treatment is usually washed with water. Water washing treatment can be performed, for example, by immersing the polyvinyl alcohol-type resin film treated with boric acid in water. The water temperature in the water washing treatment is usually 5 to 40°C.

A drying process can be performed after water washing, and the polarizer 10 can be obtained. The drying treatment can be performed using a hot air dryer or a far-infrared heater. The thickness of the polarizer 10 is 15 μm or less, preferably 10 μm or less. Setting the thickness of the polarizer 10 to 15 μm or less is advantageous for reducing the thickness of the polarizing plate 100 and, consequently, the image display device. The thickness of the polarizer 10 is usually 2 μm or more (for example, 5 μm or more).

By the drying process, the water content of the polarizer 10 is reduced to a practical level. The water content is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizer 10 is lost, and the polarizer 10 may be damaged or broken after drying. In addition, when the moisture content exceeds 20% by weight, the thermal stability of the polarizer 10 may be inferior.

(4) protective film

The protective films 21 and 22 that can be laminated on one side or both sides of the polarizer 10 are made of a light-transmitting (preferably optically transparent) thermoplastic resin such as a chain polyolefin-based resin (polypropylene-based resin, etc.), an annular polyolefin-based resins such as polyolefin-based resins (norbornene-based resins and the like); cellulosic resins such as triacetyl cellulose and diacetyl cellulose; polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate-based resin; (meth)acrylic resins such as methyl methacrylate resins; polystyrene-based resin; polyvinyl chloride-based resins; Acrylonitrile·butadiene·styrene type resin; Acrylonitrile styrene type resin; polyvinyl acetate-based resin; polyvinylidene chloride-based resins; polyamide-based resin; polyacetal-based resins; Modified polyphenylene ether type resin; polysulfone-based resins; polyethersulfone-based resins; polyarylate-based resins; polyamideimide-based resins; It may be a film made of polyimide-based resin or the like. Among them, it is preferable to use polyolefin-based resins and cellulose-based resins. In addition, in this specification, "(meth)acrylic-type resin" shows at least 1 sort(s) chosen from the group which consists of acrylic-type resin and methacrylic-type resin. The same applies to other terms with “(met)” attached.

Examples of the chain polyolefin resin include homopolymers of chain olefins such as polyethylene resins and polypropylene resins, as well as copolymers composed of two or more types of chain olefins.

Cyclic polyolefin resin is a generic term for resins polymerized using cyclic olefins as polymerized units. Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically random copolymers), and unsaturated graft polymers modified with carboxylic acids or 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.

A cellulosic resin is a cellulose obtained from raw cellulose such as cotton linter or wood pulp (hardwood pulp, conifer pulp) in which some or all of the hydrogen atoms in the hydroxyl groups are substituted with acetyl groups, propionyl groups, and/or butyryl groups. , Cellulose organic acid ester or cellulose mixed organic acid ester. Examples include cellulose acetate esters, propionic acid esters, butyric acid esters, and mixed esters thereof. Among them, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butylate are preferable.

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

As the methacrylic acid ester that can constitute the (meth)acrylic resin, a methacrylic acid alkyl ester is preferable. Examples of methacrylic acid alkyl ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, methacrylic acid and methacrylic acid alkyl esters having 1 to 8 carbon atoms in an alkyl group such as 2-ethylhexyl acrylate, cyclohexyl methacrylate, and 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, methacrylic acid esters may be used alone or in combination of two or more.

Examples of the other polymerizable monomers capable of constituting the (meth)acrylic resin include acrylic acid esters and other compounds having a polymerizable carbon-carbon double bond in the molecule. As for other polymerizable monomers, only 1 type may be used independently and 2 or more types may be used together. As the acrylic acid ester, an acrylic acid alkyl ester is preferable. As the 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, 2-hydroxyethyl acrylate, and acrylic acid alkyl esters having 1 to 8 carbon atoms in the same alkyl group. The number of carbon atoms of the alkyl group contained in the acrylic acid alkyl ester is preferably 1 to 4. In (meth)acrylic-type resin, acrylic acid ester may be used individually by 1 type, or may use 2 or more types together.

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

The thickness of the protective films 21 and 22 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. If the thickness is within this range, the polarizer 10 is mechanically protected, the polarizer 10 does not shrink even when exposed to a moist heat environment, and stable optical properties can be maintained.

The polarizing plate 100 may have a structure not having any one or both of the protective films 21 and 22 from the viewpoint of thinning. In addition, it is good also as a structure which does not have the protective film 21, and the optical film C mentioned later also has the function of the protective film 21.

When the protective film is laminated only on one side of the polarizer 10, the same active energy ray curable adhesive as the active energy ray curable adhesive described later is applied to the surface opposite to the surface on which the protective film in the polarizer 10 is laminated. A protective layer formed of a resin composition may be provided. By providing a protective layer, even if it is a structure which has a protective film only on one surface of the polarizer 10, curl accompanying a humidity change and deterioration of the polarizer 10 can be suppressed more effectively. In this specification, this protective layer is also regarded as a component of the polarizing film (A).

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

At least one of the protective films 21 and 22 has a hard coat layer, an anti-glare layer, a light diffusion layer, and a retardation layer (a retardation layer having a retardation value of 1/4 wavelength) on the outer surface (surface opposite to the polarizer 10). etc.), a surface treatment layer (coating layer) such as an antireflection layer, an antistatic layer, an antifouling layer, or an optical layer may be provided.

The protective films 21 and 22 may contain one or more additives. Examples of additives include ultraviolet absorbers, rubber particles, lubricants, dispersants, heat stabilizers, infrared absorbers, antistatic agents, antioxidants, and the like.

(5) adhesive layer

The protective films 21 and 22 can be bonded to the polarizer 10 through, for example, an adhesive layer. As the adhesive 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 water-based adhesives include adhesives made of an aqueous polyvinyl alcohol-based resin solution, water-based two-component urethane emulsion adhesives, and the like. Among them, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is preferably used. Examples of the polyvinyl alcohol-based resin include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and polyvinyl alcohol-based copolymers obtained by saponifying vinyl acetate and copolymers of other monomers copolymerizable therewith. Polymers or modified polyvinyl alcohol-based polymers obtained by partially modifying their hydroxyl groups can be used. The water-based adhesive may contain a crosslinking agent such as an aldehyde compound (eg glyoxal), an epoxy compound, a melamine-based compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

When using a water-based adhesive agent, after bonding the polarizer 10 and the protective films 21 and 22 together, it is preferable to perform a drying process for removing water contained in the water-based adhesive agent. You may provide the curing process which cures after a drying process. The temperature during curing is usually 20 to 45 ° C.

The active energy ray-curable adhesive refers to an adhesive that is cured by irradiating active energy rays such as ultraviolet rays or electron beams, for example, a curable composition containing a polymerizable compound and a photopolymerization initiator, a curable composition containing a photoreactive resin, a binder resin, and and curable compositions containing a photoreactive crosslinking agent. Preferably, it is an ultraviolet curable adhesive. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable (meth)acrylic monomers, and photocurable urethane monomers, and oligomers derived from photopolymerizable monomers. Examples of the photopolymerization initiator include substances that generate active species such as neutral radicals, anionic radicals, and cationic radicals when irradiated with active energy rays. As an active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, a curable composition containing a photocurable epoxy monomer and a photocationic polymerization initiator or a curable composition containing a photocurable (meth)acrylic monomer and a photoradical polymerization initiator, or Mixtures of these curable compositions can be preferably used.

As the photocurable epoxy-based monomer, an alicyclic epoxy compound is preferable. An alicyclic epoxy compound refers to a compound having one or more structures forming an oxirane ring together with carbon atoms of an alicyclic ring in a molecule. An alicyclic epoxy compound may be used individually by 1 type, and may use 2 or more types together. The "structure in which an oxirane ring is formed together with the carbon atoms of the alicyclic ring" is a group in the form of removing one or a plurality of hydrogen atoms from (CH ₂ ) _m in the structure shown below. In the following formula, m is an integer of 2 to 5.

Therefore, a compound in which one or a plurality of hydrogen atoms in (CH ₂ ) _m is bonded to a different chemical structure can be an alicyclic epoxy compound. One or a plurality of hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among alicyclic epoxy compounds, alicyclic epoxy compounds having an oxabicyclohexane ring (m = 4 in the formula) or an oxabicycloheptane ring (m = 5 in the formula) have excellent adhesiveness. It is desirable in that it shows The alicyclic epoxy compound preferably used below is specifically illustrated.

In the case of using an active energy ray-curable adhesive, after bonding the polarizer 10 and the protective films 21 and 22, a drying step is performed as necessary, and then the active energy ray-curable adhesive is cured by irradiation with an active energy ray. A hardening process is performed. Therefore, in the case of using an active energy ray-curable adhesive, the adhesive layer is the cured product layer. The light source of the active energy ray is not particularly limited, but an ultraviolet ray having a luminous distribution at a wavelength of 400 nm or less is preferable, specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp. , a metal halide lamp, or the like can be used.

In bonding the polarizer 10 and the protective films 21 and 22, in order to improve adhesiveness, saponification treatment, corona treatment, plasma treatment, etc. can be given to these at least any one bonding surface.

In the case where protective films are bonded to both surfaces of the polarizer 10, the adhesive for bonding these protective films may be the same type of adhesive or a different type of adhesive.

(6) optical film (C)

The polarizing plate 100 has an optical film (C) laminated on the polarizer 10 via a third pressure-sensitive adhesive layer 32 (corresponding to the pressure-sensitive adhesive layer (B)). Representative examples of the optical film (C) are the brightness enhancement film 50 and the retardation film. The optical film (C) may be a protective film as described above.

The brightness enhancing film 50 is also called a reflective polarizing film, and a polarization conversion element having a function of separating light emitted from a light source (backlight) into transmitted polarized light, reflective polarized light, or scattered polarized light is used. By disposing the luminance enhancing film 50 on the polarizer 10, it is possible to improve the emission efficiency of linearly polarized light emitted from the polarizer 10 by using retroreflective light or scattered polarized light. .

The luminance enhancing film 50 may be, for example, an anisotropic reflective polarizer. An example of the anisotropic reflective polarizer is an anisotropic multiple thin film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. 4-268505, etc.). Another example of the anisotropic reflection polarizer is a composite of a cholesteric liquid crystal layer and a λ/4 plate, and a specific example thereof is “PCF” manufactured by Nitto Denko (see Japanese Patent Laid-Open No. 11-231130, etc.). Another example of the anisotropic reflective polarizer is a reflective grid polarizer, and specific examples include a metal lattice reflective polarizer that emits reflective polarized light even in the visible light region by performing microprocessing on metal (see the specification of US Patent No. 6288840, etc.), and metal fine particles. It is a film added to a polymer matrix and stretched (see Japanese Patent Laid-Open No. 8-184701, etc.).

A surface activation treatment may be performed in advance on the joint surface of the brightness enhancing film 50 with the third pressure-sensitive adhesive layer 32 . Accordingly, it is possible to make the polarizing plate 100 excellent in wet-heat durability in which peeling hardly occurs between the third pressure-sensitive adhesive layer 32 and the brightness improving film 50 in a moist-heat environment.

As the surface activation treatment, dry treatment such as corona treatment, plasma treatment, electric discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionizing treatment (ultraviolet ray treatment, electron beam treatment, etc.); Examples include wet treatment such as ultrasonic treatment using a solvent such as water or acetone, alkali treatment, or anchor coat treatment. These treatments may be performed alone or in combination of two or more. Especially, in continuously processing a roll-shaped film, corona treatment and plasma treatment are preferable.

On the outer surface of the brightness enhancing film 50, a surface treatment layer such as a hard coat layer, an antiglare layer, a light diffusion layer, a retardation layer (such as a retardation layer having a retardation value of 1/4 wavelength), an antireflection layer, an antistatic layer, and an antifouling layer. (Coating layer) or an optical layer may be provided. By forming such a layer, adhesion to the backlight tape and uniformity of a displayed image can be improved. The thickness of the brightness enhancing film 50 is usually 10 to 100 μm, but from the viewpoint of thinning the polarizing plate 100, it is preferably 10 to 50 μm, more preferably 10 to 30 μm.

(7) adhesive layer

The first pressure sensitive adhesive layer 31 is a pressure sensitive adhesive layer disposed on the outermost surface of the polarizing plate 100, and can be used to bond the polarizing plate with a protection film to an image display element (eg, liquid crystal cell) or other optical members. The third pressure sensitive adhesive layer 32 is used to bond the optical films constituting the polarizing plate 100 (for example, an optical film such as the brightness enhancing film 50 and the polarizer 10 or the protective film 21). The first pressure-sensitive adhesive layer 31 and the third pressure-sensitive adhesive layer 32 may be formed of a pressure-sensitive adhesive composition containing a resin such as (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether as a main component. Among them, a pressure-sensitive adhesive composition comprising a (meth)acrylic resin having excellent transparency, weather resistance, heat resistance, and the like as a base polymer is suitable. An active energy ray curing type or a heat curing type may be sufficient as an adhesive composition.

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

The pressure-sensitive adhesive composition may contain only the base polymer, but usually further contains a crosslinking agent. As a crosslinking agent, it is a divalent or more metal ion, and it forms a carboxylic acid metal salt between carboxyl groups; It is a polyamine compound, and forms an amide bond between carboxyl groups; It is a polyepoxy compound or a polyol, and forms an ester bond between carboxyl groups; It is a polyisocyanate compound, and what forms an amide bond between carboxyl groups is illustrated. Among them, polyisocyanate compounds are preferred.

An active energy ray-curable pressure-sensitive adhesive composition has a property of being cured by being irradiated with active energy rays such as ultraviolet rays or electron beams, has adhesiveness even before active energy ray irradiation, and can adhere to an adherend such as a film, and can be adhered to an adherend such as a film, and is irradiated with active energy rays It is a pressure-sensitive adhesive composition having a property that can be cured by adjusting the adhesion. It is preferable that the active energy ray-curable pressure-sensitive adhesive composition is an ultraviolet curable type. The active energy ray-curable pressure-sensitive adhesive composition further contains an active energy ray-polymerizable compound in addition to the base polymer and the crosslinking agent. Moreover, a photoinitiator, a photosensitizer, etc. may be contained as needed.

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

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

The thickness of the first pressure sensitive adhesive layer 31 and the third pressure sensitive adhesive layer 32 may be 1 to 40 μm, but the dimensional change of the polarizing plate 100 is suppressed while maintaining the viewpoint of thinning and good workability of the polarizing plate 100 From a viewpoint, it is preferable to set it as 3-25 micrometers (for example, 3-20 micrometers, and also 3-15 micrometers).

(8) Separation film

The separation film 70 is a film that is temporarily applied to protect the surface of the first pressure sensitive adhesive layer 31 until it is bonded to an image display element (for example, a liquid crystal cell) or another optical member. The separate film 70 is usually composed of a thermoplastic resin film subjected to release treatment on one side, and the release treatment surface is bonded to the first pressure-sensitive adhesive layer 31 . The thermoplastic resin constituting the separation film 70 may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate. Also to the surface of the 3rd adhesive layer 32, in order to protect the surface temporarily until an optical film, such as the brightness improvement film 50, is bonded, the above separation film can be stuck. The thickness of the separate film 70 is, for example, 10 to 50 μm.

(9) Manufacturing method of polarizing plate with protection film

In the method for producing a polarizing plate with a protection film according to the present invention, at least one end face of at least one cross section in the lamination direction is laminated so that any one of the above relationships (i) to (iii) is satisfied. or end face processing after lamination. An embodiment of a method for manufacturing a polarizing plate with a protection film having a zigzag end face according to the present invention will be described. The manufacturing method of the polarizing plate with a protection film according to this embodiment is the following process:

[a] The first step of obtaining a polarizing plate by laminating the polarizing film (A) and the optical film (C);

[b] a second step of obtaining a film laminate by laminating a protective film on the polarizing plate obtained in the first step;

[c] A third step of obtaining a polarizing plate laminate by stacking a plurality of film laminates obtained in the second step, and

[d] At least one end surface of the polarizing plate laminate is polished by relatively moving an abrasive tool having an abrasive blade, which rotates around a rotational axis along the longitudinal direction of the end surface of the obtained polarizing plate laminate, with respect to the polarizing plate laminate The fourth step to do,

includes Hereinafter, each process is explained in detail.

[First step]

This process is a process of obtaining a polarizing plate by laminating at least a polarizing film (A) and an optical film (C). In this process, the 2nd process is carried out by adjusting the position of the edge part of the polarizing film (A) and the optical film (C), and laminating so that it may have an edge part which satisfies any of the conditions (i) to (iii) above. At the time of completion, the polarizing plate with a protection film concerning this invention can also be obtained.

[Second Step]

This process laminates|stacks the protection film (D) on the polarizing plate obtained in the 1st process, and obtains the film laminated body in which the polarizing film (A), the optical film (C), and the protection film (D) are laminated|stacked in this order. It is fair.

[Third Step]

This process is a process of obtaining a polarizing plate laminate by stacking a plurality of film laminates obtained in the second process of end surface unpolishing. The film laminate has a rectangular shape. A "square shape" is a square or a rectangle, and the size is not specifically limited. The number of sheets of the stacked film laminate is not particularly limited either. The film layered product used in this step is obtained by cutting a long film layered product normally.

Referring to FIG. 7 , which is a diagram for explaining a fourth process to be described later in which the end surface of the polarizing plate laminate is polished, the polarizing plate laminate W obtained by stacking a plurality of film laminates has four exposed end surfaces. , and each end face is composed of the exposed end face of each stacked film stack. A plurality of film laminates are piled up so that these four sides are aligned. The stacking direction of the film stack is not limited, and it may be stacked so that the protection film 60 is located on the upper side with respect to each film stack, and may be set in an end face processing device so that the same direction is maintained, and each film stack is stacked. Regarding the above, the protection film 60 may be piled up so as to be located on the lower side and set in an end surface processing device so that the same direction is maintained. Stacking of the film laminate can be performed either automatically or manually.

[Fourth Step]

This step is a step of obtaining a polarizing plate with a protection film having a polished end face by polishing the end face of the polarizing plate laminate obtained in the third step with a polishing tool so as to satisfy any one of the above relationships (i) to (iii). am. 7 is a schematic perspective view for explaining an example of a fourth step of polishing an end face of a polarizing plate laminate according to the present invention and an end face processing device used in this step.

Referring to FIG. 7 , an end surface processing apparatus used for polishing processing of an end surface of a polarizing plate laminate will first be described. As shown in FIG. 7, for example, the end surface processing device presses the polarizing plate stack W from the top and bottom to fix the polarizing plate stack W so that the polarizing plate stack W itself does not move and the stacked polarizers do not warp during polishing. Upper fixture 420 and lower fixture 421 for; a rotation table 431 that supports the lower fixture 421 and is rotatable around a central axis parallel to the stacking direction (z) of the polarizer; a pusher 430 attached to the upper fixture 420 and capable of rotating in the same direction as the rotary table 431 in synchronization with it; It may be provided with two polishing tools (polishing rotary bodies) 410 and 411 for polishing the end surface of the polarizing plate stacked body W.

In the end surface processing apparatus shown in FIG. 7 , the abrasive tools 410 and 411, which are disk-shaped rotary bodies provided with cutting edges protruding toward the end surface of the laminated body on the circumferential portion, are positioned at the positions of the abrasive tools 410 and 411. In a fixed state, it is rotated about a rotational axis extending along a perpendicular direction of the end face of the polarizing plate laminate, and the end face of the laminate is cut by moving the polarizing plate laminate in the x direction. The moving speed of the polarizing plate laminate with respect to the abrasive tools 410 and 411 may be, for example, 100 to 5000 mm/min. The cutting amount of the end face of the polarizing plate laminate can be, for example, 0.5 to 10 mm on average at each end face. The rotational speed of the abrasive tools 410 and 411 can be, for example, 1000 to 10000 rpm.

As shown in FIGS. 1 to 6 , in the layered film laminate in which the uppermost surface is a protection film 60 and the lowermost surface is a separate film 70, according to the rotational direction of the abrasive tools 410 and 411 , there are cases where the cross-sectional shape of the polished end face is different. For example, in the film laminate, the polishing tools 410 and 411 first insert the blade into the protection film 60, and then the optical film 50, the polarizing film 20, and the separation film 70. When the polishing process is performed by sequentially rotating in the direction in which the blade enters (hereinafter, also referred to as “pre-polishing of the protection film”), as shown in FIG. 3, the angle of the end surface of the protection film 60 relative to the surface It tends to be obtuse. On the other hand, the direction in which the blades of the abrasive tools 410 and 411 enter the separate film 70 first, and then the polarizing film 20, the optical film 50, and the protection film 60 in that order. When the polishing process is performed (hereinafter, also referred to as "post-polishing of the protection film"), the angle of the end face with respect to the surface of the protection film 60 tends to become an acute angle as shown in FIG. .

<liquid crystal panel>

A liquid crystal panel according to the present invention includes a liquid crystal cell and a polarizing plate with a protection film according to the present invention described above stacked on the liquid crystal cell. In the liquid crystal panel, the polarizing plate with a protection film is disposed so that the first pressure-sensitive adhesive layer 31 is on the liquid crystal cell side (after peeling and removing this when it has the separate film 70). In the liquid crystal panel, a liquid crystal cell, a polarizing film (A), an adhesive layer (B), an optical film (C), and a protection film (D) are laminated in this order. The liquid crystal panel is used after the protective film 60 is peeled off. It is preferable that the polarizing plate with a protection film of this invention is laminated|stacked on the back side of a liquid crystal cell.

8(a) and 8(b) are schematic diagrams showing a peeling method of a protection film. As shown in FIG. 8(a), in a state where the polarizing plate 110 with a protective film in which the polarizing plate 100 and the protective film 60 are laminated is bonded to the liquid crystal cell 200, the protective film 60 By applying a standing force to, as shown in FIG. 8 (a), the protective film 60 is raised in the direction of the arrow A to start peeling. Thereafter, an in-plane peeling force is applied to the protective film 60, and the protective film 60 is peeled in the direction of arrow B as shown in FIG. 8(b). The protective film 60 peeled from the polarizing plate 100 is removed.

In the peeling method shown in FIG. 8(a) and FIG. 8(b), the application of force to the protection film 60 causes the end of the protection film to start peeling (hereinafter, also referred to as “peeling start end”). You may apply by holding, or you may apply by holding|gripping the release tape attached to the area|region containing the peeling start end part of a protection film, and passing through it. In addition, the application of force to the protection film 60 may be performed manually by an operator, or may be automatic.

The peeling start end of the protection film 60 satisfies any one of the above relationships (i) to (iii). When force is applied to the protective film through the release tape, the release tape is attached to the region including the peel start end so as to protrude outward. 9 and 10 are plan views schematically showing an example of the application direction of the release tape on the surface of the protection film 60 . The peeling tape 310 may be attached so as to include the peeling start end of the protective film 60, and as shown in FIG. 9, it is attached to a region including the central portion of one end surface of the protective film 60. As shown in FIG. 10, it may be attached to a region including one corner of the protection film 60. As shown in FIG. 10, the side of attaching to the area including one corner of the protection film 60 is attached to the area including the center of one end surface of the protection film 60, as shown in FIG. Compared to the case of doing this, it is easier to balance during peeling, so there is a tendency that the standing force and the in-plane peeling force can be further reduced. When the protective film 60 is peeled off, the protruding end of the peel tape 310 is held directly or with a clip, etc., and force is applied to the protective film to peel the protective film 60 off. Attachment of the peeling tape 310 to the protection film 60 may be performed before or after bonding the polarizing plate 110 with a protection film to the liquid crystal cell 200 .

The in-plane peeling force of the protection film 60 can also be adjusted by the peeling angle of the protection film 60. As shown in FIG. 11, the peeling angle of the protection film 60 means the angle θ formed between the protection film 60 and the polarizing plate 100 in the peeling portion. The peeling angle of the protective film 60 is preferably 0° or more and 90° or less, more preferably 0° or more and 30° or less, since the in-plane peeling force can be set within an appropriate range.

In the present invention, when the peeling start end of the protection film 60 satisfies any one of the above relationships (i) to (iii), the force required for standing the protection film can be reduced.

[Example]

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

<Example 1>

(1) Fabrication of polarizer

A polyvinyl alcohol film having an average degree of polymerization of about 2400 and a degree of saponification of 99.9 mol% or more and having a thickness of 20 μm was uniaxially stretched about 4 times in a dry manner, and then immersed in pure water at 40 ° C. for 1 minute while maintaining a tension state, followed by iodine / It was immersed in an aqueous solution having a weight ratio of potassium iodide/water 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 having a weight ratio of potassium iodide/boric acid/water of 10.5/7.5/100. Subsequently, after washing with pure water at 5°C for 5 seconds, drying at 70°C for 180 seconds, a polarizer in which iodine was adsorbed and oriented on a uniaxially stretched polyvinyl alcohol film was obtained. The thickness of the polarizer was 7 μm.

(2) Preparation of water-based adhesive

Polyvinyl alcohol powder [trade name "KL-318" manufactured by Kuraray Co., Ltd., average degree of polymerization: 1800] was dissolved in hot water at 95°C to prepare a polyvinyl alcohol aqueous solution having a concentration of 3% by weight. A crosslinking agent [trade name "Sumirez Resin 650" manufactured by Taoka Kagaku Kogyo Co., Ltd.] was mixed with the obtained aqueous solution in a ratio of 1 part by weight to 2 parts by weight of polyvinyl alcohol powder to obtain a water-based adhesive.

(3) Fabrication of single-side protection polarizer

In the following procedure, a single-sided protective polarizing plate with a release film was produced.

In addition to continuously conveying the polarizer obtained in the above (1), the protective film is continuously unwound from the roll of the protective film [acrylic resin film, manufactured by Sumitomo Chemical Co., Ltd., thickness 20 μm] to perform corona treatment, Further, the release film was continuously unwound from the roll of the release film [trade name "KC8UX2MW", which is a TAC film manufactured by Konica Minolta Optic Co., Ltd., thickness 80 µm, no saponification treatment].

Next, inject the water-based adhesive obtained in (2) above between the polarizer and the protective film, inject pure water between the polarizer and the peeling film, and pass it between the bonding rolls to obtain a protective film / water-based adhesive layer / polarizer / pure water / It was set as the laminated|multilayer film which consists of a peeling film. Next, the laminated film is transported, passed through a drying device, and heated at 80° C. for 300 seconds to volatilize and remove the pure water intervening between the polarizer and the release film with drying of the water-based adhesive layer and attach the release film. A single-sided protective polarizing plate was obtained. The peeling film was peeled from the single-sided protective polarizing plate with a peeling film, and the single-sided protective polarizing plate (polarizing film) was obtained.

(4) Fabrication of single-sided protective polarizing plate with brightness enhancement film

An acrylic pressure-sensitive adhesive sheet [manufactured by Lintech Co., Ltd., thickness 15 μm, storage modulus at 20 ° C. 0.031 MPa] was applied to the polarizer surface of the single-sided protective polarizing plate obtained in (3) above, and a luminance improving film [3M Co., Ltd. A reflective polarizer manufactured by Kaisha, trade name "APF") was bonded with the stretching axis of the reflective polarizer parallel to the stretching direction of the polarizer to obtain a single-sided protective polarizing plate with a brightness enhancing film.

(5) Production of single-sided protective polarizing plate with separation film

An acrylic pressure-sensitive adhesive sheet with a separate film [manufactured by Lintech Co., Ltd., thickness of the pressure-sensitive adhesive layer: 20 μm] was bonded to the surface of the protective film of the single-sided protective polarizing plate with a brightness enhancing film obtained in the above (4) to protect one side with a separate film A polarizer was obtained.

(6) Production of polarizing plate with protective film

To the single-sided protective polarizing plate with a separator film obtained in the above (5), a protection film [manufactured by Fujimori Kogyo Co., Ltd., thickness: 58 μm] was bonded to the brightness enhancing film side to obtain a polarizing plate with a protection film.

(7) Abrasive processing

The long polarizing plate with a protective film obtained in (6) above is cut with a super cutter (manufactured by Ogino Seiki Seisakusho Co., Ltd., a method of cutting by a blade coming down from the top of the film) to obtain a rectangular polarizing plate with a protective film. Then, the four end surfaces were subjected to pre-polishing of the protective film using the polishing device shown in FIG. Polishing was performed by The end of the polarizing plate with a protection film obtained after polishing was typically shaped as shown in Fig. 3 (relative thickness of each layer does not coincide with Fig. 3). The outermost position P1 of the polarizing film 20 in the width direction and the outermost position P2 of the brightness enhancing film 50 in the width direction satisfy the relationship of (i) above, , the distance L between the positions P1 and P2 in the width direction was 3 μm. The polarizing plate with a protective film had a rectangular shape, and the longest side length was 6 cm, and the longest side length was 21.6 cm. The distance (L) of the width direction of the position (P1) and the position (P2) was measured using LEXT (trademark) OLS4100 by Olympus Corporation. Specifically, the distance L was measured in a non-contact manner by laser scanning the end surface of the polarizing plate with a protection film.

<Example 2>

(6) A polarizing plate with a protection film was obtained.

In the above (7), the polishing process was performed in the same manner as in Example 1 except that the polishing process was performed by post-polishing of the protection film at a clamp pressure of 0.1 MPa. The end of the polarizing plate with a protection film obtained after polishing was typically shaped as shown in Fig. 4 (relative thicknesses of the respective layers did not coincide with Fig. 4). The outermost position P1 in the width direction of the polarizing film 20 and the outermost position P2 in the width direction of the brightness enhancing film 50 satisfy the relationship of (i) above, The distance (L) in the width direction of the position (P1) and the position (P2) was 5.5 micrometers. The polarizing plate with a protective film was rectangular, and the longest side length was 6 cm, and the longest side length was 11 cm.

<Example 3>

A polarizing plate with a protection film was obtained in the same manner as in Example 2 except that the polishing process in the above (7) was not performed. The edge part of the obtained polarizing plate with a protection film was typically the same shape as shown in FIG. 1 (relative thickness of each layer does not match FIG. 1). The outermost position (P1) in the width direction of the polarizing film 20 and the outermost position (P2) in the width direction of the brightness enhancing film 50 satisfy the above relationship (iii), The distance L of the width direction of the position P1 and the position P2 was less than 1 micrometer. The polarizing plate with a protective film was rectangular, and the longest side length was 6 cm, and the longest side length was 11 cm.

<Comparative Example 1>

In the above (4), the brightness enhancing film was bonded to the surface of the protective film of the single-sided polarizing plate to produce a single-sided polarizing plate with the brightness enhancing film. A polarizing plate with a protection film of the above (6) was obtained in the same manner as in Example 1 except that it was bonded to the polarizer surface of the attached single-sided protective polarizing plate.

In the above (7), polishing was performed in the same manner as in Example 1 except that the clamping pressure was 0.1 MP. The edge of the polarizing plate with a protection film obtained after polishing was typically shaped as shown in Fig. 12 (relative thickness of each layer does not coincide with Fig. 12). The outermost position P1 in the width direction of the polarizing film 20 is inside the outermost position P2 in the width direction of the brightness enhancing film 50, and the position P1 and position The distance L in the width direction of (P2) was 3.5 μm, and none of the above relationships (i) to (iii) was satisfied. The polarizing plate with a protective film was rectangular, and the longest side length was 6 cm, and the longest side length was 11 cm.

<Comparative Example 2>

In the above (7), a polarizing plate with a protection film was obtained in the same manner as in Example 2 except that the clamping pressure was 0.05 MPa. The edge of the resulting polarizing plate with a protection film was typically shaped as shown in Fig. 13 (relative thickness of each layer does not coincide with Fig. 13). The outermost position P1 in the width direction of the polarizing film 20 is inside the outermost position P2 in the brightness enhancing film 50, and the position P1 and the position P2 The distance (L) in the width direction of was 2 μm, and none of the above relationships (i) to (iii) was satisfied. The polarizing plate with a protective film was rectangular, and the longest side length was 6 cm, and the longest side length was 11 cm.

<Comparative Example 3>

In said (7), the polarizing plate with a protection film was obtained by the same method as Example 2 except having performed the polishing process by the protection film prepolishing. The end of the cross section at the center of the short side of the obtained polarizing plate with a protection film had a shape as shown in FIG. 14 schematically (the relative thickness of each layer did not coincide with FIG. 14). The outermost position P1 in the width direction of the polarizing film 20 is inside the outermost position P2 of the brightness enhancing film 50, and the width of the position P1 and the position P2 The distance (L) in the direction was 5 μm, and none of the above relationships (i) to (iii) was satisfied. The polarizing plate with a protective film was rectangular, and the longest side length was 6 cm, and the longest side length was 11 cm.

[Evaluation test 1]

The evaluation test which confirms the peelability of the protection film was done using the polarizing plate with the protection film of Examples 1-3 and Comparative Examples 1-3. 15 is a diagram schematically showing the method of this evaluation test. In this evaluation test, first, the polarizing plate 110 with a protection film was peeled from the lowermost separation film 70 and bonded to the glass plate 330 via the pressure-sensitive adhesive layer 31 to prepare a sample for evaluation. Then, on the surface of the protection film, the peeling tape 310 (brand name: Nitto No. 31B, width 25 mm). The peeling tape 310 was attached so that the length of the portion attached to the protection film was approximately 3 cm, and the length of the protruding portion was approximately 3 cm. Then, the portion protruding outward of the peeling tape 310 was held with the clip 320 so as to form an angle of approximately 90° (peeling angle) with respect to the surface direction. The holding position of the clip 320 was approximately 2 cm from the surface of the protection film. Thereafter, without moving the clip, the glass plate 330 to which the polarizing plate was bonded was moved in the plane direction at a speed of 1.2 m/min to peel the protective film. The force required to peel the protective film at this time was measured with a load cell. The measured value at the start of peeling was the standing force, and the measured value thereafter was defined as the in-plane peeling force. Table 1 shows the measurement results.

From the results shown in Table 1, compared with the polarizing plates with a protection film of Examples 1-3, the standing force of a protection film was small compared with the polarizing plate with a protection film of Comparative Examples 1 and 2, and the peelability of a protection film was excellent. In the polarizing plate with a protection film of Comparative Example 3, the protection film could not be peeled off.

[Evaluation test 2]

Samples for evaluation were produced by the same method as in Evaluation Test 1 using the polarizing plates with protective films of Examples 1 to 3 and Comparative Examples 1 to 3. Instead of the peeling tape used in Evaluation Test 1, a peeling tape (trade name: Cellotape (registered trademark), manufactured by Nichiban Co., Ltd., width 24 mm) was used and held with a clip so that the peeling angle was approximately 180 °, In a state where the glass plate 330 was fixed so as not to move, the clip was moved at a speed of 1.0 m/min to peel off the protective film. The polarizing plate with a protection film of Examples 1-3 was able to peel the protection film, but the polarizing plate with a protection film of Comparative Examples 1-3 peeled off the protection film surface, and the protection film could not be peeled.

10: polarizer, 20: polarizing film, 21, 22: protective film, 31: first pressure-sensitive adhesive layer, 32: third pressure-sensitive adhesive layer, 50: brightness enhancement film, 60: protection film, 61: base film, 62: first 2 pressure-sensitive adhesive layer, 70: separate film, 100: polarizing plate, 110, 111, 112, 113, 114: polarizing plate with protection film, 200: liquid crystal cell, 310: peeling tape, 320: clip, 330: glass plate, 410, 411: Abrasive tool, 420 upper fixture, 421 lower fixture, 431 rotary table.

Claims (8)

A polarizing plate having a polarizing film and an optical film;
A protective film laminated on the surface of the polarizing plate,
A polarizing plate with a protection film in which the polarizing film, the optical film, and the protection film are laminated in this order,
At least one cross section in the lamination direction is located at the outermost position P1 of the polarizing film and the optical film in a direction orthogonal to the lamination direction at at least one end of the direction orthogonal to the lamination direction. The outermost position (P2) of (i) and (iii):
(i) position P1 is outside position P2;
(iii) the position P1 is inside the position P2 and the distance between the positions P1 and P2 is 1 μm or less;
A polarizing plate with a protection film that satisfies any one of these relationships. The polarizing plate with a protection film according to claim 1, wherein the polarizing film includes a polarizer and a protective film. The method of claim 1 or 2, wherein the polarizing plate further has a pressure-sensitive adhesive layer,
The polarizing plate with a protection film in which the said polarizing film, the said adhesive layer, the said optical film, and the said protection film are laminated|stacked in this order. The polarizing plate with a protection film according to claim 1 or 2, wherein the end portion exists on a polished end surface. The polarizing plate with a protection film according to claim 4, wherein the polishing end surface has a shape in which V-shaped grooves and pointed portions are alternately formed. The polarizing plate with a protection film according to claim 4, wherein the position (P1) and the position (P2) satisfy the relationship of (i) above. Equipped with a liquid crystal cell and a polarizing plate with a protection film according to claim 3,
A liquid crystal panel in which the liquid crystal cell, the polarizing film, the pressure-sensitive adhesive layer, the optical film, and the protection film are laminated in this order. A step of obtaining a film laminate in which a polarizing film, an optical film, and a protection film are laminated in this order;
At least one end surface of the film laminate is polished, and at the end surface, in a direction orthogonal to the lamination direction, the outermost position P1 of the polarizing film and the outermost position of the optical film Position (P2) is the following (i) and (iii):
(i) position P1 is outside position P2;
(iii) the position P1 is inside the position P2 and the distance between the positions P1 and P2 is 1 μm or less;
The manufacturing method of the polarizing plate with a protection film which has the process which makes it satisfy any relationship among them.

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