TWI748076B - Polarizing plate with protective film and liquid crystal panel - Google Patents

Abstract

An object of the present invention is to provide a polarizing plate with protective film capable of reducing a force required to pull up a protective film when removing the protective film.

In at least one cross section in the laminating direction of the polarizing plate with protective film according to the present invention, in at least one end portion in a direction orthogonal to the laminating direction, the outermost position P1 of the polarizing film and the outermost position P2 of the optical film with respect to the direction orthogonal to the laminating direction satisfy any one of the following conditions (i) to (iii): (i) the position P1 is in the outer side of the position P2; (ii) the position P1 and the position P2 are the same; (iii) the position P1 is in the outer side of the position P2 and the distance between the position P1 and the position P2 is 1 μm or less.

Description

Polarizing plate and LCD panel with protective film

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

Polarizers are widely used as polarized light supply elements and polarized light detection elements in display devices such as liquid crystal display devices. The polarizing plate is generally formed by bonding the protective film on one or both sides of the polarizer using an adhesive.

For the surface of the polarizing plate, in order to protect the surface during storage or the manufacturing process of a liquid crystal panel, a peelable protective film (also called a peeling film or a surface protective film, etc.) is generally attached as described in Patent Document 1. ) When making a polarizing plate with protective film. The protective film is peeled and removed after bonding the polarizing plate to the liquid crystal cell.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2016-170383 A

The peeling of the protective film is when the end of the protective film is pulled up by applying a force perpendicular to the film surface (peeling start), and then a force in the direction of the film surface is applied to the pulled up part to peel off from the polarizing plate. The force applied to the protective film during peeling can be performed while holding the end of the protective film, or through the peeling tape while holding the release tape attached to the surface of the protective film.

The force of pulling up the protective film (hereinafter also referred to as "pull-up force") and the force of peeling off the protective film in the surface direction (hereinafter also referred to as "in-plane peeling force") The pressure-sensitive adhesive used to attach the protective film to the polarizer is set to be weaker and reduced, but it will cause the protective film to float or peel off unexpectedly. Generally, the pull-up force is greater than the in-plane peel force.

In a polarizing plate with a protective film, too much force is required to pull up the protective film and it may be difficult to peel off the protective film. The general structure of a polarizing plate is a structure in which an optical film is bonded to a polarizing film via an adhesive. In the polarizing plate with a protective film including the polarizing plate constructed in this way, it may be difficult to peel off the protective film by pulling up the protective film with excessive force.

The object of the present invention is to provide a polarizing plate with a protective film that can reduce the force required to pull up the protective film when the protective film is peeled off.

The present invention provides the following methods for manufacturing polarizing plates with protective films, liquid crystal panels, and polarizing plates with protective films.

[1] A polarizing plate with a protective film, comprising: a polarizing plate having a polarizing film and an optical film, and a protective film laminated on the surface of the polarizing plate, and the polarizing film, the optical film, The aforementioned protective film; wherein, in at least one cross-section of the laminated direction of the polarizing plate with a protective film, in at least one end portion of the direction orthogonal to the aforementioned laminated direction, with respect to the direction orthogonal to the aforementioned laminated direction, the aforementioned polarizing property The outermost position P1 of the film and the outermost position P2 of the aforementioned optical film satisfy any one of the following relationships (i) to (iii): (i) position P1 is located outside of position P2; (ii) position P1 and The position P2 is the same; (iii) the position P1 is located inside the position P2, and the distance between the position P1 and the position P2 is 1 μm or less.

[2] The polarizing plate with a protective film as described in [1], wherein the polarizing film includes a polarizer and a protective film.

[3] The polarizing plate with a protective film as described in [1] or [2], the polarizing plate further has an adhesive layer, and the polarizing film, the adhesive layer, the optical film, and the above Protective film.

[4] The polarizing plate with a protective film as described in any one of [1] to [3], wherein the end portion is present on the polished end surface.

[5] The polarizing plate with a protective film as described in [4], wherein the polished end surface has a shape in which V-shaped grooves and pointed parts are alternately formed.

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

[7] A liquid crystal panel comprising a liquid crystal cell, and the polarizing plate with a protective film described in [3], and the liquid crystal cell, the polarizing film, the adhesive layer, the optical film, and the protective film are sequentially laminated membrane.

[8] A method for manufacturing a polarizing plate with a protective film, which has the following steps: obtaining a film laminate in which a polarizing film, an optical film, and a protective film are sequentially laminated; and polishing at least one end surface of the foregoing film laminate Processed so that the outermost position P1 of the polarizing film and the outermost position P2 of the optical film satisfy the following (i) to (iii) in the direction orthogonal to the laminated direction of the end surface Steps of any relationship: (i) Position P1 is located outside of position P2; (ii) Position P1 is the same as position P2; (iii) Position P1 is located inside position P2, and the distance between position P1 and position P2 is less than 1 μm .

With the polarizing plate with protective film of the present invention, when the protective film is peeled off, the force required to pull up the protective film can be reduced.

10‧‧‧Polarizer

20‧‧‧Polarizing film

21, 22‧‧‧Protective film

31‧‧‧The first adhesive layer

32‧‧‧The third adhesive layer

50‧‧‧Brightening film

60‧‧‧Protective film

61‧‧‧Base film

62‧‧‧Second adhesive layer

70‧‧‧Separation membrane

100‧‧‧Polarizer

110, 111, 112, 113, 114‧‧‧ Polarizing plate with protective film

110a, 110b, 110c, 110d, 115b, 115d, 116a, 116c

Section 115, 116‧‧‧

200‧‧‧LCD unit

310‧‧‧Peel off tape

320‧‧‧Fixture

330‧‧‧glass plate

410,411‧‧‧grinding tools

420‧‧‧Upper press tool

421‧‧‧Down press tool

430‧‧‧Press tool

431‧‧‧Rotating Table

Figure 1 is a cross-sectional view in the stacking direction of an example of a polarizing plate with a protective film of the present invention (Example 3).

Fig. 2 is a cross-sectional view showing the stacking direction of an example of the polarizing plate with a protective film of the present invention.

Fig. 3 is a cross-sectional view in the stacking direction of an example of the polarizing plate with a protective film of the present invention (Example 1).

Fig. 4 is a cross-sectional view in the stacking direction of an example of a polarizing plate with a protective film of the present invention (Example 2).

Fig. 5 is a cross-sectional view showing an example of the layer structure of the polarizing plate with protective film of the present invention.

Fig. 6 is a cross-sectional view showing an example of the layer structure of the polarizing plate with protective film of the present invention.

Fig. 7 is a schematic perspective view of the end face processing device used when the end face of the polarizing plate laminate is polished.

Fig. 8 is a schematic diagram showing the peeling method of the protective film.

Fig. 9 is a schematic diagram showing an example of the attaching direction of the release tape.

Fig. 10 is a schematic diagram showing an example of the attaching direction of the release tape.

Figure 11 is a schematic diagram showing the peeling angle.

Figure 12 is a cross-sectional view of the polarizing plate with a protective film of Comparative Example 1 in the stacking direction.

Figure 13 is a cross-sectional view of the polarizing plate with protective film of Comparative Example 2 in the stacking direction.

Figure 14 is a cross-sectional view of the polarizing plate with a protective film of Comparative Example 3 in the stacking direction.

Figure 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) The composition of the polarizing plate with protective film

The polarizing plate with protective film of the present invention is provided with: a polarizing plate with a polarizing film (A) and an optical film (C), and a protective film (D) laminated on the surface of the polarizing plate, and the layers are laminated in order to have polarizing properties Film (A), optical film (C), protective film (D). In the polarizing plate, the optical film (C) is laminated, for example, by the adhesive layer (B). At this time, in the polarizing plate with protective film, the polarizing film (A) and the adhesive layer are sequentially laminated (B), optical film (C), protective film (D).

An example of the layer structure of the polarizing plate with a protective film of the present invention will be described with reference to Fig. 1.

Figure 1 is a cross-sectional view showing the stacking direction of a polarizing plate with a protective film. As shown in Figure 1, the polarizing plate 111 with a protective film is provided with a polarizing plate 100 and a protective film 60 (corresponding to the protective film (D)) laminated on the surface of the aforementioned polarizing plate 100 on the brightness enhancement film 50 side. The polarizing plate includes a separation film 70, a first adhesive layer 31, a protective film 22, a polarizer 10 (the laminated film 20 including the protective film 22 and the polarizer 10 is equivalent to the polarizing film (A)), and the first 3 Adhesive layer 32 (equivalent to adhesive layer (B)), brightness enhancement film 50 (equivalent to optical film (C)). The protective film 60 is composed of a base film 61 and a second adhesive layer 62 laminated on the base film, and is laminated and laminated on the polarizing plate 100 with the second adhesive layer 62 interposed therebetween.

In at least one cross-section in the lamination direction of the polarizing plate with protective film of the present invention, in at least one end of the direction orthogonal to the lamination direction, the outermost polarizing film (A) is the direction orthogonal to the lamination direction The position P1 (hereinafter sometimes referred to as "position P1") and the outermost position P2 of the optical film (C) (hereinafter sometimes referred to as "position P2") satisfy the following (i) Any relationship to (iii): (i) Position P1 is located outside of position P2; (ii) Position P1 is the same as position P2; (iii) Position P1 is located inside position P2, and the distance L between position P1 and position P2 It is 1μm or less.

The end shown in FIG. 1 of the polarizing plate 111 with a protective film satisfies the relationship of (iii) above.

The so-called relationship between the position P1 and the position P2 satisfies any one of the above-mentioned (i) to (iii) relationships, which means that when the position located inside the position P2 and the distance from the position P2 is 1 μm as the reference point, the position P1 is located Outside the reference point.

The above-mentioned features of the position P1 and the position P2 of the polarizing plate with a protective film of the present invention will be specifically explained using FIG. 16. The polarizing plate with protective film is usually square. Fig. 16 is a top perspective view schematically showing a rectangular polarizing plate with a protective film. The rectangular polarizing plate 110 with a protective film has four end surfaces 110a, 110b, 110c, and 110d on the side surface (in this specification, unless otherwise specified, the "end surface" means the end surface of the side surface). At least one cross section in the stacking direction (arrow direction) of the polarizing plate 110 with a protective film of the present invention (for example, the cross sections 115 and 116 passing through two opposite end faces, which are preferably the same as the length of the polarizing plate with a protective film) In a cross section parallel to the sides or short sides), at least one end in the direction orthogonal to the stacking direction (arrow direction) (for example, the end 115b or the end 115d in the cross section 115, and the end 116a or the end 116a in the cross section 116) In the end 116c), with respect to the direction orthogonal to the stacking direction, the position P1 and the position P2 are configured to satisfy any one of the relationships (i) to (iii) described above. The aforementioned end portions (for example, the end portions 115b, 115d, 116a, and 116c) are present on any one of the end surfaces 110a, 110b, 110c, and 110d.

The polarizing plate with protective film of the present invention has an end that satisfies any one of the above-mentioned (i) to (iii) relationships. By peeling off the protective film from the end, the amount required to pull up the protective film can be reduced. force. In the polarizing plate with a protective film, it is preferable to have an end surface satisfying any one of the above-mentioned relationship (i) to (iii) in the entire area. At this time, even if the protective film is peeled off from either end of the end surface, the force required to pull up the protective film can be reduced. Furthermore, in a polarizing plate with a protective film, it is more preferable that the four end faces satisfy any one of the above-mentioned relations (i) to (iii) in the entire area. At this time, even if the protective film is peeled off from either end, the force required to pull up the protective film can be reduced.

In the end shown in FIG. 1 of the polarizing plate 111 with a protective film, the distance L between the position P1 and the position P2 is 1 μm or less, and satisfies the relationship (iii) above. Regarding all the ends of the polarizing plate 111 with a protective film, the positional relationship between the position P1 and the position P2 is set to be the same as the relationship shown in FIG. 1. The polarizing plate 111 with a protective film adjusts the end positions of the polarizing film (A) and the optical film (C) so as to satisfy the relationship of (iii) above.

Figure 2 is a cross-sectional view showing another example of a polarizing plate with a protective film. In the end portion shown in FIG. 2 of the polarizing plate 112 with a protective film, the position P1 is located outside the position P2 and satisfies the relationship (i) above. The positional relationship between the position P1 and the position P2 of all the ends of the polarizing plate 112 with a protective film is set to be the same positional relationship as the relationship shown in FIG. 2. The polarizing plate 112 with a protective film adjusts the end positions of the polarizing film (A) and the optical film (C) so as to satisfy the relationship of (i) above.

Fig. 1 and Fig. 2 specifically show the layer structure of the polarizing plate with a protective film and the positional relationship between the position P1 and the position P2. Therefore, in the example shown in Fig. 1 or Fig. 2, the layer structure of the polarizing plate with protective film and the positional relationship between the position P1 and the position P2 satisfy the relationship shown in Fig. 1 or Fig. 2 Yes, it may also include other conditions such as the relative thickness of each layer and the relative width of each layer that are different from those shown in Fig. 1 or Fig. 2. As shown in Figures 1 and 2, the polarizing laminated film (A) and the optical film (C) are laminated via an adhesive layer (the third adhesive layer 32 in Figures 1 and 2) In the polarizing plate with protective film, since the elastic modulus of the adhesive layer is lower than that of the protective film, the adhesive layer easily absorbs the force of pulling up the protective film, and there may be a need to pull up the protective film. Power situation. In particular, when the storage elastic modulus at a temperature of 20°C of the adhesive layer existing between the polarizing laminated film (A) and the optical film (C) is 0.1 MPa or less, or even 0.08 MPa or less, by using the The adhesive layer absorbs the force used to pull up the protective film, and there may be situations where a greater force is required to pull up the protective film. According to the present invention, even if there is an adhesive layer with a storage elastic modulus of 0.1 MPa or less between the polarizing laminated film (A) and the optical film (C) in a polarizing plate with a protective film at a temperature of 20° C. It can reduce the force required to pull up the protective film. In addition, the storage elastic modulus of the adhesive layer existing between the polarizing laminated film (A) and the optical film (C) at a temperature of 20°C is usually 0.01 MPa or more.

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

Measuring tool: 25mm diameter parallel plate (parallel plate)

Temperature: 20℃

Frequency: 1Hz

Strain: 1%

Positive force: 0N

Sample shape: the adhesive layer is 210μm

In the polarizing plate with protective film, the end positions of the polarizing film (A) and the optical film (C) can be adjusted at the time of lamination, or after lamination, by cutting, polishing and other end surface processing. When the end face of the polarizer with protective film is processed, more force is required to pull up the protective film. One of the reasons for this is thought to be that the end face processing changes the cross-sectional shape of the protective film, which makes it easy to disperse the force. According to the present invention, even in a polarizing plate with a protective film that is subjected to end surface processing, the force required to pull up the protective film can be reduced. Polarizing plates with protective films are sometimes cut into shapes such as rectangles and predetermined sizes in accordance with liquid crystal cells after being laminated. In addition, in order to improve the dimensional accuracy of the polarizing plate and smooth the end surface, the end surface may be polished. When the end face is ground, the end face is easy to become uneven. The end surface processing of the polarizing plate with protective film is usually carried out in a state where a plurality of polarizing plates are stacked and pressed and fixed from the top and bottom. At this time, each layer constituting the polarizing plate is temporarily deformed (thinned and enlarged) due to the pressing force from the upper and lower sides, and the end surface processing is performed in the deformed state. The degree of deformation varies depending on the size of the pressing force from the top and bottom, the layer composition and size of the polarizing plate, the thickness of each layer, and so on. Therefore, the shape of the end face at the time of end face processing is different from the shape of the end face in a state where the pressing force from the upper and lower sides is released and the deformation is restored.

3 and 4 are cross-sectional views showing an example of the polarizing plate with protective film of the present invention after such end surface processing is applied. The difference between FIGS. 3 and 4 is that the angle of the end surface of the protective film 60 with respect to the surface is an obtuse angle (FIG. 3) or an acute angle (FIG. 4). Figures 3 and 4 specifically show the layer structure of the polarizing plate with a protective film and the positional relationship between the position P1 and the position P2. Therefore, in the example shown in Fig. 3 or Fig. 4, the layer structure of the polarizing plate with protective film and the positional relationship between the position P1 and the position P2 satisfy the relationship shown in Fig. 3 or Fig. 4 Yes, it may also include other conditions such as the relative thickness of each layer, the relative width of each layer, etc., which are different from those shown in FIG. 3 or FIG. 4. Regarding all the ends of the polarizing plates 113 and 114 with a protective film, the positional relationship between the position P1 and the position P2 is set to be the same as the positional relationship shown in FIG. 3 or FIG. 4.

The end faces of the polarizing plates 113 and 114 with protective films shown in Figs. 3 and 4 include a shape in which V-shaped grooves and pointed parts are alternately formed (this shape is hereinafter referred to as a "sawtooth shape"). The polarizing plates 113 and 114 with a protective film are produced by polishing the four end faces in a state where they are pressed and fixed from the top and bottom. The end face (hereinafter referred to as the "polished end face") where the pressing force is released after being ground into a state of being deformed by the extrusion from the upper and lower sides, will appear as shown in Figures 3 and 4 In the case of a shape where V grooves and pointed parts are alternately formed. At the point where there are grinding scars, the grinding end face is different from the end face without grinding scars. The polarizing plate with protective film after polishing the end face can achieve high dimensional accuracy.

Since the viscoelasticity of the adhesive layer is higher than that of the adjacent layer and the degree of deformation due to the extrusion from the upper and lower sides will be greater, there is a tendency for the cross section to show a V-shaped groove when the extrusion force is released after grinding. . The V-shaped groove system is formed at a position where the degree of polishing is greater than the surroundings. On the other hand, since the layer with low viscoelasticity will be less deformed by the squeezing from above and below, when the squeezing force is released after grinding, the cross-section tends to show a sharp pointed part. The pointed portion is formed at a position where the degree of polishing is smaller than the surroundings. The formation position of the V-shaped groove and the pointed portion, the depth of each V-shaped groove, and the height of each pointed portion can be adjusted appropriately by adjusting the material or thickness of each layer, the pressing force from up and down, and the like.

The polarizing plates 113 and 114 with protective films shown in Figs. 3 and 4 are polished at their end faces so as to satisfy the relationship of (i) above.

The polarizing plate with a protective film of the present invention has an end that satisfies any one of the above-mentioned (i) to (iii) relationships when the protective film is peeled off (usually maintaining the relationship at the time of bonding with the liquid crystal cell). In particular, when the end surface exhibits a zigzag shape as shown in Figs. 3 and 4, it is preferable to have an end satisfying the relationship (i) above. By setting the end of the end face to the position where the protective film starts to peel off, the force required to pull up the protective film can be further reduced.

In the past, when the position to start the peeling was set at the end face of the polished end face and had a zigzag shape, there was a case where the force required to pull up the protective film was excessive. It is speculated that this is because the force applied when the protective film is peeled off fails to effectively exert its pulling force as a protective film. Even in such a case, by having an end portion that satisfies the relationship of (i) above and pulling up the protective film from the end portion, the force required to pull up the protective film can be further reduced. When the above relationship (i) is satisfied, the widthwise distance L between the position P1 and the position P2 is preferably 20 μm or less, more preferably 1 μm or more and 10 μm or less, and still more preferably 2 μm or more and 8 μm or less. When there is an adhesive layer (B) between the polarizing film (A) and the optical film (C), there is a tendency to form a V-shaped groove at the position of the adhesive layer (B), so it becomes a polarizing film (A) and the optical film (C) tend to have the end face of the V-shaped groove. In addition, the size of the polarizing plate is not limited, and is, for example, a square with a side length of 5 to 30 cm.

The distance L in the width direction between the position P1 and the position P2 can be measured, for example, using a laser microscope capable of observing the three-dimensional surface shape. Specifically, by scanning the end surface shape of the polarizing plate with a protective film at 20 times or 50 times the objective lens with a laser, the distance L can be measured without contact. Examples of the laser microscope include LEXT (registered trademark) OLS4100 manufactured by Olympus Co., Ltd.

In Figures 3 and 4, examples of the zigzag shape of the polished end surface include the case where the connection between the deepest part of the V-shaped groove and the top of the pointed part is a straight line, but the zigzag shape is not limited to this, the V-shaped groove The connecting part between the deepest part of and the top of the pointed part can also be a curve, or a combination of a curve and a straight line. In addition, in the zigzag shape, the deepest part of the V-shaped groove and the top of the pointed part have a circular shape.

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

The polarizing plate with a protective film shown in Figure 5 includes a polarizing plate 100 and a protective film 60 (corresponding to the protective film (D)) laminated on the surface of the aforementioned polarizing plate 100. The polarizing plate includes The separation film 70, the first adhesive layer 31, the protective film 22, the polarizer 10, the protective film 21 (the laminated film 20 including the protective film 22, the polarizer 10, and the protective film 21 is equivalent to the polarizing film (A)), the first 3 Adhesive layer 32 (equivalent to adhesive layer (B)), brightness enhancement film 50 (equivalent to optical film (C)).

The polarizing plate of the polarizing plate with protective film shown in Fig. 6 has the same type as that shown in Fig. 5 except that the first adhesive layer 31 is directly laminated on the surface of the polarizer 10 without the protective film 22. The same layer composition of the polarizing plate. In the polarizing plate with a protective film shown in FIG. 6, the laminated film 20 including the polarizer 10 and the protective film 21 corresponds to the polarizing film (A).

Although illustration is omitted in FIGS. 1 to 6, in the polarizing film 20, bonding of the polarizer 10 and the protective films 21 and 22 can be performed using an adhesive. In this specification, an adhesive layer containing an adhesive also serves as a constituent element of the polarizing film 20.

(2) Protective film (D)

The protective film 60 is composed of a base film 61 and a second adhesive layer 62 laminated on the protective film 61. The protective film 60 is a film used to protect the surface of the polarizing plate 100, and after the polarizing plate with the protective film is attached to the image display element such as a liquid crystal cell or other optical components, it will be combined with the protective film 60. 2 The adhesive layer 62 is peeled off together. The thickness of the protective film is, for example, 30 to 100 μm.

The resin constituting the base film 61 may be, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, and a polyester resin such as polyethylene terephthalate or polyethylene naphthalate. Thermoplastic resins such as resins and polycarbonate resins. Preferably, it is a polyester resin 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, a single-layer structure is preferred. The base film 61 may be a uniaxially stretched film or a biaxially stretched film, but it is preferably a biaxially stretched film from the viewpoints of the mechanical strength of the film, the ease of production, and the production cost.

Regarding the second adhesive layer 62, the description regarding the first adhesive layer 31 and the third adhesive layer 32 described later is cited.

(3) Polarizer

The polarizer 10 is an absorption-type polarizer with the following properties: it absorbs linearly polarized light having a vibrating surface parallel to its absorption axis, and makes linearly polarized light having a vibrating surface orthogonal to the absorption axis (parallel to the penetration axis) Through penetration, the polarizer 10 can be suitably used as a polarizing film formed by adsorbing an aligned dichroic dye on a polyvinyl alcohol-based resin film. The polarizer 10 can be manufactured, for example, by a method including the following steps: a step of uniaxially stretching a polyvinyl alcohol-based resin film; dyeing the polyvinyl alcohol-based resin film with a dichroic dye to make it adsorb two The step of chromatic pigment; the step of treating the polyvinyl alcohol resin film with the dichroic pigment with the boric acid aqueous solution; and the step of washing with water after being treated with the boric acid aqueous solution.

As the polyvinyl alcohol resin, saponified polyvinyl acetate resin can be used. In addition to polyvinyl acetate which is a homopolymer of vinyl acetate, the polyvinyl acetate-based resin can also include copolymers of vinyl acetate and other monomers copolymerizable with vinyl acetate. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having ammonium groups.

The saponification rate 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. For example, polyvinyl formaldehyde or polyvinyl acetal modified by aldehydes may also be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000. The average degree of polymerization of the polyvinyl alcohol-based resin can be determined in accordance with JIS K 6726.

Those obtained by forming such a polyvinyl alcohol-based resin into a film are used as the embryonic film of the polarizer 10 (polarizing film). The method of forming a polyvinyl alcohol-type resin into a film is not specifically limited, A well-known method can be adopted. The thickness of the polyvinyl alcohol-based embryo film is not particularly limited, but in order to set the thickness of the polarizer 10 to 15 μm or less, usually 5 to 35 μm, preferably 20 μm or less. To stretch a polyvinyl alcohol-based embryo film with a thickness of more than 35 μm to obtain a polarizer 10 with a thickness of 15 μm or less, it is necessary to increase the stretching magnification, and when the thickness of the polarizer 10 is set to 15 μm or less, it will be effective in a high temperature environment. The shrinkage in size will also increase. In addition, when the thickness is less than 5 μm, the workability during stretching is lowered, and defects such as cutting are likely to occur when the polarizer is manufactured.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before, during, or after dyeing the dichroic dye. When uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before or during the boric acid treatment. In addition, uniaxial stretching may be performed in these plural stages.

In uniaxial stretching, it can be uniaxially stretched between rollers with different peripheral speeds, or it can be uniaxially stretched by using a heated roller. In addition, uniaxial stretching may be dry stretching in which it is stretched in the air, or wet stretching in which the polyvinyl alcohol-based resin film is stretched in a state where the polyvinyl alcohol-based resin film is swelled using a solvent or water. The stretching ratio is usually 3 to 8 times.

Regarding the 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 can be adopted. As a dichroic dye, iodine or a dichroic organic dye can be used. In addition, the polyvinyl alcohol-based resin film is preferably immersed in water before the dyeing treatment.

Regarding the dyeing treatment with iodine, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is generally adopted. The content of iodine in the 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 the aqueous solution is usually 20 to 40°C. On the other hand, with regard to the dyeing process performed by the dichroic organic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic organic dye is generally adopted. The aqueous solution containing the dichroic organic dye may contain inorganic salts such as sodium sulfate as a dyeing auxiliary. The content of the dichroic organic dye in the aqueous solution is usually 1×10 ^-4 to 10 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution is usually 20 to 80°C.

Regarding the boric acid treatment after dyeing with a dichroic dye, a method of immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid is generally adopted. When iodine is used as a dichroic dye, the aqueous solution containing boric acid preferably 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 the aqueous solution is usually 0.1 to 15 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution may be 50°C or higher, for example, 50 to 85°C.

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

After washing with water, a drying process is applied to obtain a polarizer 10. The drying process 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 beneficial to the thinning of the polarizer 100 and even the image display device. The thickness of the polarizer 10 is usually 2 μm or more (for example, 5 μm or more).

Through the drying process, the moisture content of the polarizer 10 is reduced to a practical level. The moisture 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 polarizer 10 will lose flexibility, and the polarizer 10 may be damaged or cracked after it dries. In addition, when the moisture content is higher than 20% by weight, the thermal stability of the polarizer 10 may deteriorate.

(4) Protective film

The protective films 21, 22, which can be laminated on one or both sides of the polarizer 10, can be made of a thermoplastic resin having translucency (preferably optically transparent), for example: chain polyolefin resin (polypropylene Resin, etc.), cyclic polyolefin resin (norbornene resin, etc.) polyolefin resin; such as cellulose triacetate and cellulose diacetate; such as polyethylene terephthalate , Polybutylene terephthalate polyester resin; polycarbonate resin; (meth)acrylic resin such as methyl methacrylate resin; polystyrene resin; polyvinyl chloride resin; Acrylonitrile/butadiene/styrene resin; acrylonitrile/styrene resin; polyvinyl acetate resin; polyvinylidene chloride resin; polyamide resin; polyacetal resin; modified poly Phenylene ether-based resin; polyether-based resin; polyether-based resin; polyarylate-based resin; polyimide-based resin; polyimide-based resin and other films. Among them, polyolefin-based resins and cellulose-based resins are preferably used. In addition, in this specification, the "(meth)acrylic resin" refers to at least one selected from the group consisting of acrylic resins and methacrylic resins. The same applies to other terms in the note "(methyl)".

In addition to homopolymers of chain olefins such as polyethylene resins and polypropylene resins, the chain polyolefin resins may also include copolymers containing two or more chain olefins.

Cyclic polyolefin resin is a general term for resins polymerized with cyclic olefin as a polymerization unit. 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. (Representatively random copolymers), and graft polymers modified with unsaturated carboxylic acids or derivatives thereof, and hydrogenated products thereof. Among them, it is preferable to use a norbornene-based resin obtained by using a norbornene-based monomer such as a norbornene or a polycyclic norbornene-based monomer as a cyclic olefin.

The so-called cellulose resin is obtained from raw cellulose such as cotton linter or wood pulp (hardwood pulp, conifer pulp), and is part or all of the hydrogen atoms in the hydroxyl groups of cellulose. And/or cellulose organic acid ester or cellulose mixed organic acid ester after butyryl group substitution. For example, those containing cellulose acetate, propionate, butyrate, and these mixed esters, etc. are mentioned. Among them, cellulose triacetate, cellulose diacetate, cellulose acetate propionate, and cellulose acetate butyrate.

The (meth)acrylic resin is a polymer containing structural units derived from a (meth)acrylic monomer. The polymer is usually a methacrylate-containing polymer. It is preferably a polymer containing a ratio of structural units derived from methacrylate of 50% by weight or more with respect to all structural units. The (meth)acrylic resin may be a homopolymer of methacrylate or a copolymer containing structural units derived from other polymerizable monomers. In this case, the ratio of structural units derived from other polymerizable monomers is preferably 50% or less with respect to all structural units.

The methacrylate that can constitute the (meth)acrylic resin is preferably an alkyl methacrylate. Examples of alkyl methacrylates include: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, Tertiary butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, alkyl methacrylate whose alkyl group has 1 to 8 carbon atoms . The carbon number of the alkyl group contained in the alkyl methacrylate is preferably 1 to 4. Among (meth)acrylic resins, methacrylate may be used alone or in combination of two or more.

The above-mentioned other polymerizable monomers that can constitute the (meth)acrylic resin include acrylates and other compounds having polymerizable carbon-carbon double bonds in the molecule. The other polymerizable monomers can be used singly or in combination of two or more. The acrylate is preferably an alkyl acrylate. Examples of alkyl acrylates include: 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, alkyl acrylate having 1 to 8 carbon atoms, etc. The carbon number of the alkyl group contained in the alkyl acrylate is preferably 1 to 4. Among (meth)acrylic resins, acrylate may be used alone or in combination of two or more.

Other compounds having polymerizable carbon-carbon double bonds in the molecule include vinyl compounds such as ethylene, propylene, and styrene, or vinyl cyanide compounds such as acrylonitrile. Other compounds having polymerizable carbon-carbon double bonds in the molecule can be used alone or in combination of two or more.

The thickness of the protective films 21 and 22 is usually 1 to 100 μm, but from the viewpoint of strength, handleability, etc., it is preferably 5 to 60 μm, and more preferably 5 to 50 μm. If the thickness is within this range, the polarizer 10 can be mechanically protected, even if the polarizer 10 is exposed to a humid and hot environment, it will not shrink, and stable optical characteristics can be maintained.

From the viewpoint of thinning, the polarizing plate 100 may have a configuration that does not have either or both of the pellicle films 21 and 22. In addition, in terms of not having the structure of the protective film 21, the optical film (C) described later can also be made to have the function of the protective film 21.

When the protective film is layered on only one area of the polarizer 10, it is also possible to provide the polarizer 10 on the side opposite to the surface on which the protective film is laminated, with the same active energy ray hardening as the active energy ray curable adhesive described later. A protective layer formed by a sexual resin composition. By providing the protective layer, even if it is a structure having a protective film on only one side of the polarizer 10, curling due to humidity changes or deterioration of the polarizer 10 can be further effectively suppressed. In this specification, such a protective layer also serves as a constituent element of the polarizing film (A).

When the protective film is attached to both sides of the polarizer 10, the protective film may be composed of the same type of thermoplastic resin, or may be composed of different types of thermoplastic resins. In addition, the thickness may be the same or different. Furthermore, they may have the same phase difference characteristics or have different phase difference characteristics.

At least any one of the protective films 21 and 22 may be provided with a hard coat layer, an anti-glare layer, a light diffusion layer, a retardation layer (having 1/4 The retardation layer of the retardation value of the wavelength, etc.), the surface treatment layer (coating layer) or the optical layer of the anti-reflection layer, antistatic layer, and antifouling layer.

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, and antioxidants.

(5) Adhesive layer

The protective films 21 and 22 can be bonded to the polarizer 10 via an adhesive layer, for example. As the adhesive for forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and a water-based adhesive or an active energy ray-curable adhesive is preferable.

Examples of the water-based adhesive include an adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin, and an aqueous two-component urethane-based emulsion adhesive. Among them, an aqueous adhesive containing a polyvinyl alcohol-based resin aqueous solution is suitably used. In addition to the vinyl alcohol homopolymer obtained by saponifying the polyvinyl acetate which is a homopolymer of vinyl acetate, the polyvinyl alcohol resin can also use vinyl acetate and other monomers that can be copolymerized with the vinyl acetate. The polyvinyl alcohol-based copolymer obtained by the saponification treatment of the copolymer, or the modified polyvinyl alcohol-based polymer after the hydroxyl part is modified. The aqueous adhesive may contain crosslinking agents such as aldehyde compounds (glyoxal, etc.), epoxy compounds, melamine compounds, methylol compounds, isocyanate compounds, amine compounds, and polyvalent metal salts.

When a water-based adhesive is used, it is preferable to perform a drying step for removing water contained in the water-based adhesive after bonding the polarizer 10 and the protective films 21 and 22. After the drying step, an aging step for aging may be provided. The temperature during maturation is usually 20 to 45°C.

The above-mentioned 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, and a curable composition containing photoreactive Curable composition of resin, curable composition containing binder resin and photoreactive crosslinking agent, etc. Preferably, it is an ultraviolet curable adhesive. Examples of polymerizable compounds include photocurable epoxy monomers, photocurable (meth)acrylic monomers, photocurable urethane monomers, or photopolymerizable monomers derived from photocurable monomers. Body oligomers. Examples of the photopolymerization initiator include those containing active species that generate neutral radicals, anionic radicals, and cationic radicals due to irradiation of active energy rays. The active energy ray curable adhesive containing a polymerizable compound and a photopolymerization initiator, preferably a curable composition containing a photocurable epoxy monomer and a photocationic polymerization initiator, or a photocurable A curable composition of a (meth)acrylic monomer and a photoradical polymerization initiator, or a mixture of these curable compositions.

The photocurable epoxy-based monomer is preferably an alicyclic epoxy compound. The so-called alicyclic epoxy compound refers to a compound having at least one structure in the molecule that forms an oxirane ring together with the carbon atoms of the alicyclic ring. The alicyclic epoxy compound can be used individually by 1 type or in combination of 2 or more types. The so-called "the structure forming an oxirane ring together with the carbon atoms of the alicyclic ring" refers to a group obtained by removing one or more hydrogen atoms from _{(CH 2} ) _{m in the structure shown below.} In the following formula, m is an integer from 2 to 5.

Therefore, _{the group from which one or more hydrogen atoms in (CH 2} ) _m is removed is bonded to a compound of other chemical structure to form an alicyclic epoxy compound. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted by a linear alkyl group such as a methyl group or an ethyl group. Among the alicyclic epoxy compounds, the alicyclic ring has an oxabicyclohexane ring (m=4 in the above formula) or an oxabicycloheptane ring (m=5 in the above formula) Epoxy compounds are preferred because they exhibit excellent adhesiveness. Specific examples of alicyclic epoxy compounds that can be preferably used are listed below.

When using an active energy ray curable adhesive, after bonding the polarizer 10 and the protective films 21, 22, a drying step is performed as necessary, and then the active energy ray curable adhesive is cured by irradiating the active energy ray. Hardening step. Therefore, when an active energy ray-curable adhesive is used, the adhesive layer is a cured product layer. The light source of the active energy ray is not particularly limited. It is preferably ultraviolet light having a luminous distribution below the wavelength of 400nm. Specifically, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, and microwaves can be used. Exciting mercury lamps, metal halide lamps, etc.

When attaching the polarizer 10 to the protective films 21 and 22, in order to improve adhesiveness, a saponification treatment, a corona treatment, a plasma treatment, etc. may be applied to the bonding surface of at least any one of these.

When the protective film is attached to both sides of the polarizer 10, the adhesive used for attaching the protective film may be the same type of adhesive or different types of adhesives.

(6) Optical film (C)

The polarizing plate 100 has an optical film (C) laminated on the polarizer 10 via the third adhesive layer 32 (corresponding to the 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 also be a protective film as described above.

The brightness enhancement film 50 is also called a reflective polarizing film, and a polarization conversion element having the function of separating light emitted from a light source (backlight) into penetrating polarized light and reflecting polarized light or scattering polarized light can be used. By disposing the brightness enhancement film 50 on the polarizer 10, the return light belonging to the reflected polarized light or the scattered polarized light can be utilized to improve the emission efficiency of the linearly polarized light emitted from the polarizer 10.

The brightness enhancement film 50 may be, for example, an anisotropic reflective polarizer. An example of anisotropic reflective polarizer is an anisotropic multilayer film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in another vibration direction. A specific example is "DBEF" made by 3M (see Japanese Patent Laid-Open No. 4-268505, etc.). Another example of anisotropic reflective polarizer is a composite of a cholesterol liquid crystal layer and a quarter-wave plate. A specific example is "PCF" manufactured by Nitto Denko (refer to Japanese Patent Application Publications). Bulletin 11-231130, etc.). Another example of the anisotropic reflective polarizer is the reflective barrier polarizer. The specific example is a metal lattice reflective polarizer that emits reflected polarized light even in the visible light region if fine processing is applied to the metal (refer to US Patent No. 6288840 No. Specification, etc.), a film formed by adding metal fine particles to a polymer matrix and stretching (refer to Japanese Patent Application Laid-Open No. 8-184701, etc.).

The bonding surface of the brightness enhancement film 50 and the third adhesive layer 32 may be surface-activated in advance. Thereby, the polarizing plate 100 with excellent wet and heat durability, which is unlikely to be peeled off between the third adhesive layer 32 and the brightness enhancement film 50 in a hot and humid environment, can be manufactured.

Surface activation treatment can include: corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionizing active ray treatment (ultraviolet treatment, electron beam treatment, etc.) and other dry treatments; Wet treatments such as ultrasonic treatment, alkaline treatment, and anchor coating treatment using solvents such as water or acetone. These treatments can be performed individually or in combination of two types. Among them, when the roll-shaped film is to be processed continuously, corona treatment and plasma treatment are preferred.

The outer surface of the brightness enhancement film 50 can be provided with a hard coat layer, an anti-glare layer, a light diffusion layer, a retardation layer (a retardation layer with a retardation value of 1/4 wavelength, etc.), an anti-reflection layer, and an antistatic layer. , Surface treatment layer (coating layer) or optical layer of anti-fouling layer. By forming this layer, the adhesion to the backlight tape or the uniformity of the displayed image can be improved. The thickness of the brightness enhancement 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 adhesive layer 31 is an adhesive layer disposed on the outermost surface of the polarizing plate 100, and can be used to bond the polarizing plate with a protective film to an image display element (such as a liquid crystal cell) or other optical components. The third adhesive layer 32 is used to bond the optical films constituting the polarizer 100 (for example, the optical film such as the brightness enhancement film 50 and the polarizer 10 or the protective film 21). The first adhesive layer 31 and the third adhesive layer 32 can be composed of (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resins as main components. It is composed of adhesive composition. Among them, an adhesive composition having a (meth)acrylic resin as a base polymer, which is excellent in transparency, weather resistance, and heat resistance, is preferable. The adhesive composition can be of active energy ray hardening type or thermosetting type.

Regarding the (meth)acrylic resin (base polymer) used in the adhesive composition, for example, one kind or two or more kinds such as butyl (meth)acrylate and (meth)acrylic acid can be suitably used. Ethyl, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate (meth)acrylate as a polymer or copolymer of monomers. It is preferable to copolymerize a polar monomer in the base polymer. Examples of polar monomers include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, (meth)acrylic acid N, N -Dimethylaminoethyl and glycidyl (meth)acrylate monomers having carboxyl group, hydroxyl group, amide group, amino group, epoxy group, etc.

The adhesive composition may only contain the above-mentioned base polymer, but usually contains a crosslinking agent. The crosslinking agent may include metal ions with a valence of 2 or higher, and a metal salt of carboxylic acid is formed between the carboxyl group; those that are polyamine compounds and an amide bond is formed between the carboxyl group, and those that are polyepoxy compounds or polyvalents. Alcohol, and the ester bond is formed between the carboxyl group; belongs to the polyisocyanate compound, and the amide bond is formed between the carboxyl group. Among them, polyisocyanate compounds are preferred.

The so-called active energy ray curable adhesive composition refers to the property of being cured by the irradiation of active energy rays such as ultraviolet rays or electron beams, and it has adhesiveness even before the active energy rays are irradiated and can adhere to the film. It can be cured by irradiation of active energy rays to adjust the properties of adhesion. The active energy ray curable adhesive composition is preferably an ultraviolet curable adhesive composition. The active energy ray curable adhesive composition contains an active energy ray polymerizable compound in addition to a base polymer and a crosslinking agent. Furthermore, a photopolymerization initiator, photosensitizer, etc. may be contained as needed.

The adhesive composition may contain fine particles, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, adhesiveness imparting agents, fillers (metal powder or other Inorganic powder, etc.), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, defoamers, corrosion inhibitors, photopolymerization initiators and other additives.

The first adhesive layer 31 and the third adhesive layer 32 can be formed by applying an organic solvent dilution of the above-mentioned adhesive composition on a substrate and drying it. The substrate may be other optical films such as polarizer 10, protective films 21, 22, brightness enhancement film 50, separation film (for example, separation film 70), and the like. When an active energy ray curable adhesive composition is used, by irradiating the formed adhesive layer with active energy rays, a cured product having a desired degree of curing can be made.

The thickness of the first adhesive layer 31 and the third adhesive layer 32 may be 1 to 40 μm, but from the viewpoint of thinning the polarizing plate 100, and the viewpoint of controlling the dimensional change of the polarizing plate 100 while maintaining good workability From a point of view, it is preferably set to 3 to 25 μm (for example, 3 to 20 μm, or even 3 to 15 μm).

(8) Separation membrane

The separation film 70 is a film to be temporarily attached in order to protect the surface of the image display element (for example, a liquid crystal cell) or another optical member before bonding the first adhesive layer 31 to the image display element (for example, a liquid crystal cell) or other optical members. The separation film 70 is usually composed of a thermoplastic resin film with a release treatment on one side, and the release treatment surface is attached to the first adhesive layer 31. The thermoplastic resin constituting the separation membrane 70 may be, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, and a polyester resin such as polyethylene terephthalate or polyethylene naphthalate. Wait. Before bonding to the optical film such as the brightness enhancement film 50, in order to temporarily protect the surface of the third adhesive layer 32, the same separation film as described above may be pasted on the surface of the third adhesive layer 32 in advance. The thickness of the separation membrane 70 is, for example, 10 to 50 μm.

製造方法 (9) Polarizing plate with protective film

Production method

The method of manufacturing a polarizing plate with a protective film of the present invention is performed in such a way that at least one end of the direction orthogonal to the layering direction in at least one cross-section of the layering direction satisfies any one of the above-mentioned relationships (i) to (iii) After layering or layering, the end face is processed. An embodiment of the method for manufacturing a polarizing plate with a protective film having a sawtooth-shaped end surface of the present invention will be described. The method of manufacturing a polarizing plate with a protective film of this embodiment includes the following steps: [a] The first step of laminating a polarizing film (A) and an optical film (C) to obtain a polarizing plate; [b] In the first step The second step of laminating a protective film on the polarizing plate obtained in step 1 to obtain a film laminate; [c] the third step of stacking a plurality of film laminates obtained in the second step to obtain a polarizing plate laminate; and [d ] A polishing tool with a grinding knife and rotating along the longitudinal axis of the end face of the obtained polarizing plate laminate is relatively moved with respect to the polarizing plate laminate, thereby moving at least one of the polarizing plate laminates The fourth step of grinding the end face. The steps are described in detail below.

[Step 1]

This step is a step of laminating at least the polarizing film (A) and the optical film (C) to obtain a polarizing plate. In this step, the end positions of the polarizing film (A) and the optical film (C) are adjusted, and they are laminated so that they have an end satisfying any one of the conditions (i) to (iii) above, Thereby, the polarizing plate with protective film of the present invention can also be obtained at the end of the second step.

[Step 2]

This step is a step of laminating a protective film (D) on the polarizing plate obtained in the first step to obtain a film laminate in which a polarizing film (A), an optical film (C), and a protective film (D) are sequentially laminated.

[Step 3]

This step is a step of stacking the film laminate obtained in the second step in which the end faces of a plurality of sheets are not polished to obtain a polarizing plate laminate. The film laminate has a square shape. The so-called "square" is a square or a rectangle, and its size is not particularly limited. The number of laminated film laminates is also not particularly limited. The thin film laminate used in this step is usually obtained by cutting a long film laminate.

With reference to Figure 7 of the drawing for explaining the fourth step of polishing the end surface of the polarizing plate laminate, the polarizing plate laminate W obtained by superimposing a plurality of film laminates has 4 exposed Each of the end surfaces is constituted by the exposed end surfaces of the overlapped film laminates. The film stacking system of plural sheets overlaps so that these four sides become uniform. The overlapping direction of the film laminates is not limited. The film laminates can be overlapped so that the protective film 60 is located on the upper side, and then set in the end surface processing device while maintaining this direction, or the film laminates can be protected The film 60 is overlapped so that it is located on the lower side, and then it is installed in the end surface processing device while maintaining the orientation. The overlap of the film laminate can be performed automatically or manually.

[Step 4]

This step is a step of using a polishing tool to polish the end face of the polarizing plate laminate obtained in the third step to satisfy any one of the relationships (i) to (iii) above to obtain a polarizing plate with a polished end face with a protective film. Fig. 7 is a schematic perspective view for explaining the fourth step of polishing the end surface of the polarizing plate laminate of the present invention and an example of the end surface processing device used in this step.

With reference to Fig. 7, first, the end surface processing device used in the polishing processing of the end surface of the polarizing plate laminate will be described. As shown in Fig. 7, the end surface processing device may be provided with the following: the polarizing plate laminate W is pressed from above and below to be fixed so that the polarizing plate laminate W itself will not move and not move during the polishing process. The overlapped polarizers are offset from the upper pressing tool 420 and the lower pressing tool 421; the lower pressing tool 421 is supported and the rotating table 431 is capable of rotating around a central axis parallel to the stacking direction z of the polarizing plate as the center; A pressing tool 430 attached to the upper pressing tool 420 and capable of rotating in the same direction as the rotating table 431 at the same time as the rotating table 431; 2 grinding tools for grinding the end surface of the polarizing plate laminate W Body) 410,411.

In the end surface processing device shown in Fig. 7, the grinding tools 410 and 411, which are disk-shaped rotating bodies of cutting blades protruding toward the end surface of the laminated body, are provided on the circumferential portion. In the fixed state, it rotates around the axis of rotation stretched along the vertical direction of the end face of the polarizing plate laminate to move the polarizing plate laminate in the x direction to cut the end face of the laminate. The moving speed of the polarizing plate laminate with respect to the polishing tools 410 and 411 can be set to, for example, 100 to 5000 mm/min. The cutting amount of the end faces of the polarizing plate laminate can be set to be 0.5 to 10 mm on average for each end face, for example. The rotation speed of the grinding tools 410 and 411 can be set to, for example, 1,000 to 10,000 rpm.

Regarding the film laminate composed of the protective film 60 on the top and the separation film 70 on the bottom as shown in Figures 1 to 6, there will be a polished product depending on the direction of rotation of the polishing tools 410 and 411. When the cross-sectional shapes of the end faces are different. For example, in a film laminate, the polishing tools 410 and 411 first enter the blades of the protective film 60, and then the blades enter the directions of the optical film 50, the polarizing film 20, and the separation film 70 in order to perform the polishing process. In the case (hereinafter referred to as "protective film first polishing"), as shown in FIG. 3, the angle of the end surface with respect to the surface of the protective film 60 tends to become obtuse. On the other hand, in the case where the grinding tools 410 and 411 first enter the separation film 70 with the blade, and then the blade enters the polarizing film 20, the optical film 50, and the protective film 60 in order to rotate to perform the polishing process ( When referred to as "protective film post-polishing" below), as shown in Fig. 4, the angle of the end surface relative to the surface of the protective film 60 tends to become an acute angle.

<LCD panel>

The liquid crystal panel of the present invention includes a liquid crystal cell and the polarizing plate with a protective film of the present invention laminated on the liquid crystal cell. In the liquid crystal panel, the polarizing plate with a protective film is arranged so that the first adhesive layer 31 becomes (after peeling and removing it when it has the separation film 70) on the liquid crystal cell side. In the liquid crystal panel, a liquid crystal cell, a polarizing film (A), an adhesive layer (B), an optical film (C), and a protective film (D) are laminated in this order. The liquid crystal panel is used after the protective film 60 is peeled off. The polarizing plate with a protective film of the present invention is preferably laminated on the back side of the liquid crystal cell.

Figure 8 (a) and (b) are schematic diagrams showing the peeling method of the protective film. As shown in Figure 8(a), from the state where the polarizer 110 with the protective film laminated with the polarizer 100 and the protective film 60 is attached to the liquid crystal cell 200, a pulling force is applied to the protective film 60, as shown in Section 8. As shown in Figure (a), the protective film 60 is pulled up in the direction of arrow A to start peeling. Then, 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 Figure 8 (a) and (b), the force applied to the protective film 60 can be applied when holding the end of the protective film (hereinafter referred to as the "peeling start end"). It can also be performed through the tape while holding the peeling tape attached to the area including the peeling start end of the protective film. In addition, the force applied to the protective film 60 may be manual or automatic directly performed by the operator.

The peeling start end of the protective film 60 satisfies any one of the relationships (i) to (iii) described above. When a force is applied to the protective film through the release tape, the release tape is applied to the area including the peeling start end so that the peeling tape protrudes from the outside. 9 and 10 are plan views schematically showing an example of the attaching direction of the release tape on the surface of the protective film 60. The peeling tape 310 only needs to be attached so as to include the peeling start end portion of the protective film 60, and it can be attached to the area including the center portion of the end surface of the protective film 60 as shown in Fig. 9 or as shown in Fig. 10. It is attached to an area including a corner of the protective film 60 as shown in the figure. As shown in Figure 10, it is easier to stick to the area including the corner of the protective film 60 than when it is attached to the center of the one end surface of the protective film 60 as shown in Figure 9. Achieve balance during peeling, so there is a tendency to further reduce the pull-up force and in-plane peeling force. When peeling the protective film 60, the protruding end of the peeling tape 310 is held directly or with a jig or the like, and force is applied to the protective film to peel the protective film 60. The peeling tape 310 can be attached to the protective film 60 before or after attaching the polarizing plate 110 with the protective film to the liquid crystal cell 200.

The in-plane peeling force of the protective film 60 can also be adjusted by the peeling angle of the protective film 60. The so-called peeling angle of the protective film 60, as shown in FIG. 11, means the angle θ between the protective film 60 and the polarizing plate 100 in the peeled portion. Since the peeling angle of the protective film 60 can set the in-plane peeling force to an appropriate range, it is preferably 0° or more and 90° or less, and more preferably 0° or more and 30° or less.

In the present invention, by making the peeling start end of the protective film 60 satisfy any of the relationships (i) to (iii) above, the force required to pull up the protective film can be reduced.

(Example)

Examples and comparative examples are listed below to explain the present invention more specifically, but the present invention is not limited to these examples.

<Example 1>

(1) Production of polarizer

A polyvinyl alcohol film with an average degree of polymerization of about 2400, a saponification rate of 99.9 mol% or more, and a thickness of 20 μm was uniaxially stretched to about 4 times in dry form, and then immersed in pure water at 40°C for 1 minute while maintaining the stretched state. , Immersed in an aqueous solution with a weight ratio of iodine/potassium iodide/water of 0.1/5/100 at 28°C for 60 seconds. Then, it was immersed in an aqueous solution with a weight ratio of potassium iodide/boric acid/water of 10.5/7.5/100 at 68°C for 300 seconds. Then, it was washed with pure water at 5°C for 5 seconds and then dried at 70°C for 180 seconds to obtain a polarizer with iodine adsorbed and aligned on a uniaxially stretched polyvinyl alcohol film. The thickness of the polarizer is 7 μm.

(2) Preparation of water-based adhesive

Polyvinyl alcohol powder (trade name "KL-318" manufactured by Kuraray Co., Ltd., average polymerization degree 1800) was dissolved in 95°C hot water to prepare a polyvinyl alcohol aqueous solution with a concentration of 3% by weight. The crosslinking agent (trade name "Sumirez Resin 650" manufactured by Taoka Chemical Industry Co., Ltd.) was mixed in the obtained aqueous solution at a ratio of 1 part by weight to 2 parts by weight of the polyvinyl alcohol powder to prepare an aqueous adhesive.

(3) Production of single-sided protective polarizing plate

The single-sided protective polarizing plate with release film was produced in the following procedure.

The polarizer obtained in (1) above is continuously transported, while the protective film is continuously rolled out from the protective film [acrylic resin film, manufactured by Sumitomo Chemical Co., Ltd., thickness 20μm] and subjected to corona treatment. The release film was continuously rolled out from a roll of release film (trade name "KC8UX2MW" of TAC film manufactured by Konica Minolta Opto 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, and at the same time inject pure water between the polarizer and the release film, and pass it through the bonding rollers to form a protective film/water-based adhesive Laminated film of agent layer/polarizer/pure water/release film. Next, the laminated film is transported and heated at 80°C for 300 seconds through a drying device to dry the water-based adhesive layer and at the same time volatilize and remove the pure water existing between the polarizer and the release film to obtain a release film The single-sided protection polarizer. 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) Production of single-sided protective polarizer with brightness enhancement film

Acrylic pressure-sensitive adhesive sheet (manufactured by Printec Co., Ltd., thickness 15μm, storage modulus of elasticity at 20°C: 0.031MPa) is used to add brightness enhancement film (product name of reflective polarizer manufactured by 3M Co., Ltd.) "APF") is bonded to the polarizer surface of the single-sided protective polarizer obtained in (3) above in a manner parallel to the stretching axis of the reflective polarizer in the stretching direction of the polarizer to obtain a single-sided with brightness enhancement film Protect the polarizer.

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

On the protective film surface of the single-sided protective polarizer with brightness enhancement film obtained in the above (4), an acrylic pressure-sensitive adhesive sheet with a separation film (manufactured by Printec Co., Ltd., thickness of the adhesive layer 20μm) is attached, Obtain a single-sided protective polarizer with a separation film.

(6) Production of polarizing plate with protective film

A protective film (manufactured by Fujimori Industrial Co., Ltd., thickness 58 μm) was attached to the single-sided protective polarizer with a separation film obtained in (5) above to obtain a polarizer with a protective film.

(7) Grinding processing

The long polarizing plate with protective film obtained in (6) above is cut with a super cutter (manufactured by Ogino Seiki Seisakusho Co., Ltd. by cutting from the top of the film with a knife) to make a square When using a polarizing plate with a protective film and using the polishing device shown in Figure 7 to make the clamp pressure between the upper clamp 420 and the lower clamp 421 shown in Figure 7 become 0.15 MPa The 4 end faces are first polished with a protective film to be polished. The end of the polarizing plate with protective film obtained after polishing is schematically shown in the shape shown in Figure 3 (the relative thickness of each layer is not consistent with that in Figure 3). 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 enhancement film 50 satisfy the relationship (i) above, and the width L distance between the position P1 and the position P2 is 3 μm . The polarizing plate with protective film is square, and the longest length of the short side is 6cm, and the longest length of the long side is 21.6cm. The distance L in the width direction between the position P1 and the position P2 was measured using LEXT (registered trademark) OLS4100 manufactured by Olympus Co., Ltd. Specifically, the distance L is measured in a non-contact manner by laser scanning the end surface of the polarizing plate with a protective film.

<Example 2>

Except that a cycloolefin polymer film (COP) [trade name: ZF-14, manufactured by Japan Zeon Co., Ltd., thickness 13μm] was used as the protective film in (3) above, the rest was obtained by the same method as in Example 1. The above (6) polarizing plate with protective film.

The polishing process was performed in the same manner as in Example 1, except that in the case where the clamping pressure was set to 0.1 MPa in the above (7), the polishing process was performed by the protective film post polishing. The end of the polarizing plate with protective film obtained after the polishing process is schematically shown in the shape shown in Figure 4 (the relative thickness of each layer is not consistent with that in Figure 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 enhancement film 50 satisfy the relationship of (i) above, and the widthwise distance L between the position P1 and the position P2 is 5.5 μm.

The polarizing plate with protective film is square, and the longest length of the short side is 6cm, and the longest length of the long side is 11cm.

<Example 3>

The polarizing plate with a protective film was obtained in the same manner as in Example 2 except that the polishing process of (7) was not performed. The end of the obtained polarizing plate with a protective film is schematically shown in the shape shown in Fig. 1 (the relative thickness of each layer is not consistent with that in 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 enhancement film 50 satisfy the above relationship (iii), and the widthwise distance L between the position P1 and the position P2 is less than 1μm. The polarizing plate with protective film is square, and the longest length of the short side is 6cm, and the longest length of the long side is 11cm.

<Comparative Example 1>

In addition to the above (4), the brightness enhancement film is attached to the protective film surface of the single-sided polarizer to produce a single-sided polarizer with a brightness enhancement film, and the acrylic pressure sensitive film with a separation film is used in the above (5) The type adhesive sheet was attached to the polarizer surface of the single-sided protective polarizer with a brightness enhancement film, and the rest was the same as in Example 1 to obtain the above-mentioned (6) polarizer with a protective film.

Except that the clamping pressure was 0.1 MP in the above (7), the grinding process was performed in the same manner as in Example 1. The end of the polarizing plate with protective film obtained after the polishing process is schematically shown in the shape shown in Figure 12 (the relative thickness of each layer is not consistent with that in Figure 12). The outermost position P1 in the width direction of the polarizing film 20 is located inside the outermost position P2 in the width direction of the brightness enhancement film 50, and the widthwise distance L between the position P1 and the position P2 is 3.5 μm, none of which satisfies the above Any relationship from (i) to (iii). The polarizing plate with protective film is square, and the longest length of the short side is 6cm, and the longest length of the long side is 11cm.

<Comparative Example 2>

Except for setting the clamping pressure to 0.05 MPa in (7) above, the same method as in Example 2 was used to obtain a polarizing plate with a protective film. The end of the obtained polarizing plate with protective film is schematically shown in Fig. 13 (the relative thickness of each layer is not consistent with that in Fig. 13). The outermost position P1 in the width direction of the polarizing film 20 is located inside the outermost position P2 of the brightness enhancement film 50, and the widthwise distance L between the position P1 and the position P2 is 2 μm, and none of the above (i) to (iii) any relationship.

The polarizing plate with protective film is square, and the longest length of the short side is 6cm, and the longest length of the long side is 11cm.

<Comparative Example 3>

Except that in the above (7), the protective film was first polished and polished, the same method as in Example 2 was used to obtain a polarizing plate with a protective film. The end portion of the center section of the short side of the obtained polarizing plate with protective film is schematically shown in the shape shown in Fig. 14 (the relative thickness of each layer is not consistent with that in Fig. 14). The outermost position P1 in the width direction of the polarizing film 20 is located inside the outermost position P2 of the brightness enhancement film 50, and the widthwise distance L between the position P1 and the position P2 is 5 μm, none of which satisfies the above (i) to (iii) any relationship. The polarizing plate with protective film is square, and the longest length of the short side is 6cm, and the longest length of the long side is 11cm.

[Evaluation Test 1]

Using the polarizing plates with protective films of Examples 1 to 3 and Comparative Examples 1 to 3, an evaluation test for confirming the peelability of the protective film was performed. Figure 15 is a diagram schematically showing the method of this evaluation test. In this evaluation test, first, the lowermost separation film 70 is peeled off, and then the polarizing plate 110 with a protective film is bonded to the glass plate 330 via the adhesive layer 31 to prepare an evaluation sample. Then, on the surface of the protective film, the peeling tape 310 (trade name: Nitto No. 31B, width 25mm) is attached so that the position (the center of the short side) where the distance L is measured above becomes the peeling start point. The position and the end protruding outside. The length of the part attached to the protective film of the peeling tape 310 is about 3 cm, and the length of the part attached to the protruding part is about 3 cm. Then, the part protruding from the outer side of the peeling tape 310 is held with a jig 320 so that it becomes an angle (peeling angle) of about 90° with respect to the surface direction. The holding position of the clamp 320 is set to a position about 2 cm away from the surface of the protective film. Finally, the glass plate 330 bonded to the polarizing plate was moved in the surface direction at a speed of 1.2 m/min without moving the jig, and the protective film was peeled off. The force required to peel off the protective film at this time is measured with a dynamometer. The measured value at the point when the peeling started was taken as the pull-up force, and the subsequent measured value was taken as the in-plane peeling force. Table 1 shows the measurement results.

From the results shown in Table 1, it can be seen that, compared to the polarizing plates with protective films of Comparative Examples 1 and 2, the protective films of Examples 1 to 3 have lower pull-up force of the protective film, and the protective film The peelability is excellent. In the polarizing plate with a protective film of Comparative Example 3, the protective film could not be peeled off.

[Evaluation Test 2]

Using the polarizing plates with protective films of Examples 1 to 3 and Comparative Examples 1 to 3, the evaluation sample was produced by the same method as the evaluation test 1. Use peeling tape (trade name: Cellotape (registered trademark), manufactured by Nichiban Co., Ltd., width 24mm) instead of the peeling tape used in Evaluation Test 1, and hold it with a jig so that the peeling angle becomes approximately 180°. In a state where the glass plate 330 is fixed so as not to move, the jig is moved at a speed of 1.0 m/min to peel off the protective film. The protective film-attached polarizing plates of Examples 1 to 3 can peel off the protective film, but the release tape of the protective film-attached polarizing plates of Comparative Examples 1 to 3 peeled off from the surface of the protective film and the protective film could not be peeled off.

10‧‧‧Polarizer

20‧‧‧Polarizing film

22‧‧‧Protective film

31‧‧‧The first adhesive layer

32‧‧‧The third adhesive layer

50‧‧‧Brightening film

60‧‧‧Protective film

61‧‧‧Base film

62‧‧‧Second adhesive layer

70‧‧‧Separation membrane

100‧‧‧Polarizer

113‧‧‧Polarizing plate with protective film

P1‧‧‧Location

P2‧‧‧Location

L‧‧‧Distance

Claims (8)

A polarizing plate with a protective film, which is to be attached to an image display element. The polarizing plate with a protective film includes: a polarizing plate with a polarizing film and an optical film, and a protective film laminated on the surface of the aforementioned polarizing plate , And the polarizing film, the optical film, and the protective film are laminated in this order from the image display element side; wherein, in at least one cross-section of the laminated direction of the polarizing plate with the protective film, it is aligned with the laminated direction. In at least one end of the crossing direction, the outermost position P1 of the polarizing film and the outermost position P2 of the optical film satisfy the following (i) to (iii) with respect to the direction orthogonal to the laminated direction. Any relationship: (i) position P1 is located outside of position P2; (ii) position P1 is the same as position P2; (iii) position P1 is located inside position P2, and the distance between position P1 and position P2 is less than 1 μm. The polarizing plate with a protective film as described in claim 1, wherein the polarizing film includes a polarizer and a protective film. For the polarizing plate with protective film described in item 1 or 2 of the scope of patent application, the aforementioned polarizing plate further has an adhesive layer, and the polarizing plate with protective film is laminated with the aforementioned polarized light sequentially from the image display element side Sexual film, the adhesive layer, the optical film, and the protective film. The polarizing plate with protective film as described in item 1 or 2 of the scope of patent application, wherein the aforementioned end portion is present on the polished end surface. The polarizing plate with protective film described in claim 4, wherein the polished end surface is a shape in which V-shaped grooves and pointed parts are alternately formed. The polarizing plate with protective film as described in item 4 of the scope of patent application, wherein the position P1 and the position P2 satisfy the relationship of (i) above. A liquid crystal panel is provided with an image display element and a polarizing plate with a protective film described in item 3 of the scope of patent application. The image display element is a liquid crystal cell, and the polarizing plate with a protective film is sequentially laminated with the aforementioned The liquid crystal cell, the polarizing film, the adhesive layer, the optical film, and the protective film. A manufacturing method of a polarizing plate with a protective film, the polarizing plate with a protective film is to be attached to an image display element, and the manufacturing method has the following steps: obtaining a layer of polarized light sequentially from the image display element side The step of a film laminate of a transparent film, an optical film, and a protective film; at least one end surface of the film laminate is polished so that the polarizing film is the most polarized film in the direction orthogonal to the laminate direction among the end surfaces. Steps where the outer position P1 and the outermost position P2 of the aforementioned optical film satisfy any one of the following relationships (i) to (iii): (i) the position P1 is located outside of the position P2; (ii) the position P1 and the position P2 is the same; (iii) The position P1 is located inside the position P2, and the distance between the position P1 and the position P2 is 1 μm or less.

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