TW201727281A - Polarizing plate, image display device, and method for manufacturing polarizing plate - Google Patents

Abstract

A polarizing plate comprises a polarizer 2, and protective films 3, 3 that laminated on both sides thereof. Both of the protective films 3, 3 are formed into a predetermined shape. Protective films 3, 3 are laminated respectively on whole surface of single side of the polarizer 2, and at least a part of the end portions 2a of the polarizer 2 is positioned at the inner side of an end portion 3a of at least one protective film 3.

Description

Polarizing plate, image display device, and manufacturing method of polarizing plate

The present invention relates to a polarizing plate, an image display device, and a method of manufacturing a polarizing plate.

Conventionally, a polarizing plate has been known as one of optical components constituting a liquid crystal display device or the like. The polarizing plate is generally applied to a single-sided or two-layer protective film of the polarizer to reinforce the mechanical strength, thermal stability, water resistance and the like of the polarizer. For example, in Patent Document 1, an application layer of a polymer coating layer or a film is provided as a transparent protective layer (protective film) on one surface or both surfaces of a polarizing plate.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-303730

However, the desired protective effect can be obtained for the main surface of the polarizer in which the protective film is laminated, but for the end portion (side surface side) of the polarizer Then the protection is insufficient. Actually, at the time of or after the polarizing plate is attached to the liquid crystal cell, scratches or cracks may occur at the end portions of the polarizer.

Accordingly, an object of the present invention is to provide a polarizing plate that sufficiently protects an end portion of a polarizer, and a method of manufacturing the polarizing plate. Further, it is an object of the invention to provide an image display device including the polarizing plate.

The present invention provides a polarizing plate comprising a polarizer and a protective film laminated on both sides thereof, wherein any one of the protective films is formed into a predetermined shape, and the protective film is laminated on the entire surface of one side of the polarizer, and the polarized film is polarized. The end of at least a portion of the sheet is located further inside the end of at least one of the protective films.

In the polarizing plate, the end portion of the polarizer is located at the inner side of the end portion of at least one of the protective films, so that the end portion of the polarizer is physically protected. Therefore, in the operation of the polarizing plate, when the side surface of the polarizing plate is subjected to punching, damage or cracking of the end portion of the polarizing plate can be prevented.

In the present invention, the end portion of at least a portion of the polarizer may be located further inside than the end portions of the protective films of both sides. At this time, since the end portions of the polarizers are protected from both sides of the polarizer, it is possible to further prevent scratches or cracks at the ends of the polarizers.

Further, all of the ends of the polarizer may be located further inside than the end of at least one of the protective films. At this time, all the ends of the polarizer can be protected.

The polarizing plate of the present invention may have a shape in which the shape of the planar view conforms to the shape of the region in which the polarizing plate is bonded, and may be, for example, a quadrangular shape in plan view. If In such a shape, it is easy to apply to various items such as a liquid crystal display device.

In the polarizing plate of the present invention, a separation film may be laminated on the side of the unprotected film of the polarizer to pass through the adhesive layer, and a temporary protective film may be laminated on the other side of the uncovered protective film of the polarizer. In this case, the protective film can be prevented from being damaged or worn, and the separation film can be peeled off during use of the polarizing plate to expose the adhesive layer, and the polarizing plate can be attached to another article by the adhesive force.

The present invention provides an image display device including the above polarizing plate. For example, when the polarizing plate is bonded to a liquid crystal display device such as a liquid crystal cell, the end portion of the polarizer can be physically protected.

Moreover, the present invention provides a method of producing a polarizing plate in which a first protective film having a predetermined shape is formed, and a polarizing film is laminated so as to cover a first protective film over a single surface, and the polarizing plate is coated with a polarizing film. A method of laminating a second protective film on the one surface of the other side, wherein the polarizer is located further inside the end portion of at least a part of the protective film of at least one of the first protective film and the second protective film The first protective film, the polarizer, and the second protective film are laminated.

By the above manufacturing method, the above polarizing plate can be manufactured.

According to the present invention, it is possible to provide a polarizing plate that sufficiently protects an end portion of a polarizer, and a method of manufacturing the polarizing plate. Further, an image display device including the polarizing plate can be provided.

1A, 1B‧‧‧ polarizing plate

2‧‧‧ polarizer

2a‧‧‧End of polarizer

3‧‧‧Protective film

3a‧‧‧End of protective film

4‧‧‧Separation membrane

4a‧‧‧End of separation membrane

5‧‧‧Adhesive layer

5a‧‧‧End of the adhesive layer

6‧‧‧ Temporary protective film

6a‧‧‧Temporary protective film at the end

8‧‧‧Liquid Crystal Unit

9‧‧‧LCD panel

10‧‧‧Liquid crystal display device (image display device)

Fig. 1 is a perspective view of a polarizing plate according to a first embodiment of the present invention.

Fig. 2(a) is a cross-sectional view taken along line IIa-IIa of Fig. 1, and Fig. 2(b) is a cross-sectional view taken along line IIb-IIb of Fig. 1.

Fig. 3 is a cross-sectional view showing a polarizing plate according to a second embodiment of the present invention.

Fig. 4 is a cross-sectional view showing a liquid crystal display device.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals will be given to the same or corresponding parts, and the description will not be repeated. The dimensional ratio of each drawing is not necessarily the same as the actual one, and in particular, the thickness is exaggeratedly depicted.

<First embodiment>

As shown in FIG. 1 and FIG. 2, the polarizing plate 1A of the present embodiment is formed of the entire surface layer protective films 3 and 3 formed on both surfaces of the film-shaped polarizing film 2. Any of the protective films 3 and 3 is formed into the same shape as a rectangular shape in plan view, and this shape is the outer shape of the polarizing plate 1A. That is, the polarizing plate 1A is configured to have a rectangular shape in plan view.

The size of the main surface of the polarizing plate 1A, that is, the size of the protective films 3, 3 can be arbitrarily set in accordance with the application target of the polarizing plate 1A. For example, the length of the diagonal may be, for example, 5 to 250 cm, 10 to 150 cm, or 12 to 100 cm. Further, the ratio of the lengths of the adjacent sides, that is, the aspect ratio of the polarizing plate 1A is preferably 1:9 to 5:5, more preferably 2:8 to 5:5, and 3:7 to 5: 5 is even better.

The end portion 2a of the polarizer 2 covers the entire circumference of the polarizer 2 The end portions 3a, 3a of the protective films 3, 3 are further recessed inside. That is, in the cross-sectional view shown in Fig. 2, the side faces of the polarizing plate 1A are formed in a concave shape in which the side faces of the polarizing plates 2 are recessed with respect to the side faces of the protective films 3, 3. Here, the end portion 2a of the polarizer 2 is preferably 1 to 500 μm on the inner side of the end portions 3a, 3a of the protective film 3, 3, more preferably 1 to 300 μm on the inner side, and 1 to 50 μm on the inner side. good. When the end portion 2a of the polarizer 2 is in the above range, the effect of physically protecting the end portion 2a of the polarizer 2 is particularly high, and the display surface can be broadly ensured when the image display device is constructed.

The polarizer 2 preferably covers the entire end thereof with respect to the end portion 3a of the protective film 3, and the end portion 2a of the polarizer 2 is located inside with the same length. If the length is different for the whole circumference, the polarizing plate 1A is different in the laminated state in various places, and it is predicted that complicated warpage will be formed when the polarizing plate 1A is warped. Therefore, the side of the polarizing plate 1A preferably covers the entire circumference thereof, and the side faces of the polarizing plate 2 are recessed by the same length with respect to the side faces of the protective films 3, 3.

Further, the polarizer 2 may be a stretched film, and at the same time, the end portion 2a of the polarizer 2 which is preferably on the side perpendicular to the direction of the optical axis (absorption axis) is located at the end portions 3a, 3a of the protective film 3, 3. More inside. Generally, the side surface parallel to the optical axis is highly resistant to punching, but the side surface perpendicular to the optical axis or having a side inclined with respect to the optical axis (for example, 40° or more and 140° or less) is low in impact resistance. Therefore, when the end portion 2a of the polarizer 2 is located inside the end portions 3a, 3a of the protective films 3, 3 on the side perpendicular to the optical axis, the effect of protecting the end portion 2a of the polarizer 2 is particularly exhibited.

On the side of the polarizing plate 1A, the side faces of the polarizing plate 2 are recessed portions with respect to the side faces of the protective films 3, 3, so as not to be embedded in other structures. The piece is preferred. That is, it is preferable that the side surface of the polarizer 2 is opened and in contact with the outside air. In the case where the adhesive or the like described later is oozing out in the portion, the other portion of the polarizing plate 1A is contaminated or the peripheral device of the polarizing plate 1A is applied. Further, if the protective film 3 and the polarizer 2 or the like are formed by heat during processing (laser cutting, heat cutting, etc.), or the protective film 3, 3 which protrudes, the end portion of the polarizing plate 1A itself. When the recessed portion (the portion) is embedded, the degree of freedom of the end portion of the polarizing plate 1A is reduced, which is considered to be the cause of the end wave warpage defect. Further, since the portion of the interference portion for the punching disappears, the direct transfer of the side surface of the polarizer 2 is generated. Further, when the molten material such as the protective film 3 or the polarizing plate 2 is oozing out at the portion due to heat, the polarizing performance of the end portion of the polarizing plate 1A is lowered.

The polarizer 2 and the protective film 3 may be laminated, and the polarizer 2 and the protective film 3 formed into a film may be bonded to each other through an adhesive. The first and second figures are not shown as an adhesive layer.

The material of the polarizer 2 can be a known material which has been conventionally used for the production of a polarizing plate, and examples thereof include a polyvinyl alcohol resin, a polyvinyl acetate resin, an ethylene/vinyl acetate (EVA) resin, a polyamide resin, and a poly Ester resin or the like. Among them, a polyvinyl alcohol-based resin is preferred. When it is formed into a film shape by bonding to the protective film 3, it is preferable to perform dyeing of the film extending through one axis by iodine or a dichroic dye, followed by boric acid treatment. As will be described later, the film-shaped polarizer can be used by cutting out an arbitrary size when manufacturing a polarizing plate. The film-shaped polarizer 2 produced from such materials has low mechanical strength, thermal stability, and water resistance, and is particularly low at the end of the film. Therefore, cracks are likely to occur at the end of the polarizer 2 by the treatment at the time of manufacture of the polarizing plate. Scratch.

The thickness of the polarizer 2 is preferably 2 to 75 μm, more preferably 2 to 50 μm, still more preferably 2 to 30 μm.

The protective film 3 is a film that prevents cracking or scratching of the main surface or the end portion of the polarizing plate 2. Here, the "protective film" refers to a film which can be laminated on the film of the polarizer 2 and physically laminated at the position closest to the polarizer 2.

The protective film 3 is composed of various transparent resin films known in the field of polarizing plates. For example, a cellulose resin represented by triethyl fluorenyl cellulose, a polyolefin resin represented by a polypropylene resin, a cyclic olefin resin represented by a norbornene resin, and a poly The methyl methacrylate resin is a representative example of an acrylic resin, and a polyethylene terephthalate resin is a polyester resin represented by a representative example. Among them, cellulose-based resins are representative.

The protective film 3 may be a film having no optical function, or may be a film having an optical function of a so-called retardation film or a brightness enhancement film.

The thickness of the protective film 3 is preferably 5 to 90 μm, more preferably 5 to 80 μm, still more preferably 5 to 50 μm.

When an adhesive is used for the laminate of the polarizer 2 and the protective film 3, various adhesives used in the production of the conventional polarizing plate can be used as the adhesive. For example, from the viewpoints of weather resistance, inflection rate, cationic polymerizability and the like, an epoxy resin which does not contain an aromatic ring in the molecule is preferable. Further, it is preferred to perform hardening by irradiation with an active energy ray (ultraviolet rays or hot wires).

Epoxy resin is, for example, hydrogenated epoxy resin, alicyclic An epoxy resin, an aliphatic epoxy resin or the like is preferred. A polymerization initiator (for example, a photocationic polymerization initiator for polymerization by ultraviolet irradiation, a thermal cationic polymerization initiator for polymerization by heat irradiation) or further additives may be added to the epoxy resin. A sensitizer or the like is prepared by preparing an epoxy resin composition for coating.

Further, as the adhesive agent, an acrylic resin such as acrylamide, acrylate, urethane acrylate or epoxy acrylate; or a polyvinyl alcohol-based water-based adhesive can be used.

The polarizing plate 1A is bonded to one side or both sides of a display unit (image display element) such as a liquid crystal cell. The polarizing plate 1A may further contain other optical layers laminated on the protective film 3. The other optical layer may be, for example, a reflective polarizing film that transmits polarized light or a polarized light having opposite properties, a film having an anti-glare function having a concave-convex shape on the surface, and a film having a surface reflection preventing function; A reflective film having a reflective function on the surface; a semi-transmissive reflective film having a reflecting function and a transmitting function; a viewing angle compensation film.

The thickness of the polarizing plate 1A composed of the polarizer 2 and the three layers of the protective films 3, 3 is preferably 10 to 500 μm, more preferably 10 to 300 μm, still more preferably 10 to 200 μm.

The polarizing plate 1A can be manufactured, for example, in the following manner. First, the two protective film 3, 3 are cut out from the long film roll formed of the material constituting the protective film 3. The size and aspect ratio of the cut rectangle are determined according to the application target of the polarizing plate 1A. An adhesive is applied to one side of one of the protective films (first protective films) 3. The area where the adhesive is applied is not guaranteed. The entire surface of the film 3 is a region in which the film-shaped polarizer 2 is laminated.

Next, the polarizer 2 is cut into a rectangular shape from the long film roll formed of the material constituting the polarizer 2. The size of the cut rectangle is smaller than the size of the protective film 3. The reduced component is such that the end portion 2a of the polarizer 2 is recessed more inward than the end portion 3a of the protective film 3. The cut film-shaped polarizer 2 was laminated on the surface of the protective film 3 coated with the adhesive. Here, the laminate is formed such that the entire surface of one side of the polarizer 2 is placed inside the surface of the protective film 3. Here, the polarizer 2 is coated on the protective film as seen from the protective film 3 side. When an active energy ray-curable resin is used as an adhesive, the active energy ray is irradiated here to cure the adhesive.

Then, a further protective film (second protective film) 3 is laminated on the entire surface of the other side of the polarizer. The laminate of the protective film 3 here is carried out by covering the single surface of the polarizer 2 by the surface of the protective film 3. When an active energy ray-curable resin is used as the adhesive, the active energy ray is also irradiated here to harden the adhesive.

The polarizing plate 1A was fabricated in the above order.

The end portion 2a of the polarizing plate 1A as described above is located inside the end portion 3a of the protective film 3, so that the end portion of the polarizing plate 2 is physically protected. Therefore, in the operation when the polarizing plate 1A is attached to, for example, a liquid crystal cell, when the side surface of the polarizing plate 1A is subjected to punching, only the end portion 3a of the protective film 3 is washed, and scratching at the end portion of the polarizing plate 2 can be prevented. Or cracked. This effect can be exerted even in a further operation after the polarizing plate 1A is bonded to the liquid crystal cell or the like. Moreover, it is also helpful in improving the durability of the thermal shock test of the polarizing plate 1A.

Further, since the polarizing plate 1A protects the end portion 2a of the polarizing plate 2 by the end portions 3a, 3a of the protective films 3, 3 laminated on both surfaces of the polarizing plate 2, in particular, in the narrow frame-like tendency of the liquid crystal cell in recent years, It can exert its effects well. That is, when the frame of the liquid crystal cell to which the polarizing plate 1A is attached has a general width, the liquid crystal cell itself has a function of protecting the polarizer 2 from physical protection. However, if the liquid crystal cell has a narrow frame, the effect of protection is small. At this time, the end portion 3a of the protective film 3 on the liquid crystal cell side contributes to a large ratio of protection of the end portion 2a of the polarizing plate 2. Further, when the end portion 2a of the polarizer 2 is positioned at a length of 500 μm or less inside the end portions 3a and 3a of the protective films 3 and 3, it is applied to a screen of a television screen or a mobile terminal (mobile phone, smart phone, etc.). It is easy to ensure a wide display surface.

The end portion 2a of the polarizer 2 covers the entire circumference of the end portion 3a of the protective film 3, so that the above-described effect can be exhibited by covering the entire circumference of the polarizing plate 1A.

Further, since the polarizing plate 1A has a rectangular shape in plan view, it is easily applied to various articles such as a liquid crystal display device.

<Second embodiment>

As shown in FIG. 3, the polarizing plate of the present invention may further laminate the separation film 4 or the temporary protective film 6 to the laminated body of the polarizing plate 2 and the protective film 3.

The polarizing plate 1B of the second embodiment is formed by laminating the separation film 4 through the adhesive layer 5 on one surface of the polarizing plate 1A of the first embodiment (that is, the surface of the protective film 3 which is not laminated with the polarizing film 2). Moreover, on the other side of the polarizing plate 1A (that is, the other laminated protective film 3 is not laminated) The surface of the temporary protective film 6 is laminated.

The adhesive layer 5 is a layer that functions as a polarizing plate 1B when it is bonded to another article (for example, a liquid crystal cell). The adhesive layer 5 may be composed of an acrylic resin, a polyoxymethylene resin, a polyester, a polyurethane, a polyether or the like.

The thickness of the adhesive layer 5 is preferably 2 to 500 μm, more preferably 2 to 200 μm, still more preferably 2 to 50 μm.

The method of laminating the adhesive layer 5 on the protective film 3 may be, for example, a method of applying a solution containing the above resin or an optional component to the protective film 3, or forming the adhesive layer 5 on the separation film 4 with the solution. Then, a method of laminating the protective film 3 is carried out. The end portion 5a of the adhesive layer 5 preferably covers the entire circumference of the end portion 3a of the protective film 3.

The separation membrane 4 is a peelable film which is bonded to protect the pressure-sensitive adhesive layer 5 or prevent adhesion of foreign matter or the like, and is peeled off when the polarizing plate 1B is used to expose the pressure-sensitive adhesive layer 5 . The separation membrane 4 can be composed of, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin of polypropylene, or a polyester-based resin of polyethylene terephthalate. Among them, a stretch film of polyethylene terephthalate is preferred.

The end portion 4a of the separation membrane 4 preferably covers the entire circumference in conformity with the position of the end portion 5a of the adhesive layer 5. Moreover, the separation membrane 4 can be easily peeled off when the polarizing plate 1B is used, and the release treatment can be carried out by a polyphthalocyanine resin or the like on the surface contacting the adhesive layer 5.

The thickness of the separation membrane 4 is preferably 5 to 200 μm, more preferably 5 to 150 μm, still more preferably 5 to 100 μm.

The temporary protective film 6 is a film which can be peeled off, and is a film for protecting the surface of the protective film 3 in which the temporary protective film 6 is laminated from being damaged or worn. The material of the temporary protective film 6 can be the same as that of the protective film 3, wherein polyethylene terephthalate, polyethylene naphthalate, polyethylene phthalate, polyterephthalic acid A polyester resin such as butadiene ester is preferred.

The temporary protective film 6 may have a weak adhesive layer laminated on the surface of the film in addition to the film of the substrate. After the temporary protective film 6 is laminated on the protective film 3, it is bonded to the protective film 3 until the polarizing plate 1B is used, and is peeled off from the protective film 3 at the time of use. It is preferable that the end portion 6a of the temporary protective film 6 conforms to the position of the end portion 3a of the protective film 3 over the entire circumference.

The thickness of the temporary protective film 6 is preferably 5 to 200 μm, more preferably 5 to 150 μm, still more preferably 5 to 100 μm.

According to the polarizing plate 1B, the protective film 3 can prevent damage and abrasion, and when the polarizing plate 1B is used, the separation film 4 is peeled off to expose the adhesive layer 5, and the polarizing plate 1B is bonded to other articles such as liquid crystal cells and organic by the adhesive force thereof. On the EL device, an image display device can be constructed.

For example, as shown in FIG. 4, for example, the polarizing plate 1B of the peeling separation film 4 is bonded to both surfaces of the liquid crystal cell 8 to form the liquid crystal panel 9, and the backlight is combined thereon (surface light source device; The liquid crystal display device 10 can be manufactured by showing the same and other members. On the other hand, a touch panel or the like can be provided on the surface on which the temporary protective film 6 is peeled off.

In the above, a description will be given of a suitable embodiment of the present invention. However, the present invention is not limited to the above embodiments. For example, in the above embodiment, the end portion 2a of the polarizing plate 2 is shown to be located on the inner side of the end portions 3a, 3a of the protective films 3, 3 of the two sides, but the inner portion may not be located. Covers the entire week of polarizer 2. At this time, the end portion 2a of the polarizer 2 protects only the portion located further inside the end portions 3a, 3a of the protective films 3, 3. In an example, the end portion 2a of the polarizer 2 (the opposite sides of the polarizer 2) having only the side perpendicular to the optical axis direction of the polarizer 2 may be located at the end of the protective film 3, 3 3a, 3a are more inside.

Further, in the above-described embodiment, the entire circumference of the polarizer 2 is covered so as to be inside with the same length. However, the degree of depression of the polarizer 2 may be changed depending on the location. For example, when the polarizing plate is operated in advance to know the portion which is susceptible to punching, it is preferable to increase the width of the recess of the end portion of the polarizer in advance for the object having the above-described complicated warpage.

Further, one of the protective films 3 may have the same shape as the polarizer 2. That is, the end portion 3a of one of the protective films 3 may coincide with the position of the end portion 2a of the polarizer 2.

Further, in the above-described embodiment, the polarizing plates 1A and 1B are rectangular in plan view, but may be other square shapes such as a trapezoid, a parallelogram, a square, or the like, or may be circular or round. In other words, the polarizing plates 1A and 1B can be formed into any shape in accordance with the shape of the articles to which the polarizing plates 1A and 1B are bonded, and in particular, the shape in plan view may be the same as the shape of the curved regions of the bonded polarizing plates 1A and 1B. The shape.

1A‧‧‧Polar plate

2‧‧‧ polarizer

2a‧‧‧End of polarizer

3‧‧‧Protective film

3a‧‧‧End of protective film

Claims (8)

A polarizing plate comprising a polarizer and a protective film laminated on both surfaces thereof, wherein any one of the protective films is formed into a predetermined shape, and the protective film is laminated on a whole surface of one surface of the polarizer, The end portion of at least a portion of the polarizer is located further inward of the end portion of the protective film of at least one of the polarizing plates. The polarizing plate according to claim 1, wherein an end portion of at least a part of the polarizer is located further inward than an end portion of the protective film. The polarizing plate according to claim 1 or 2, wherein all of the end portions of the polarizer are located at the inner side of at least one of the ends of the protective film. The polarizing plate according to any one of claims 1 to 3, wherein the polarizing plate has a shape in plan view that matches a shape of a region in which the polarizing plate is bonded. The polarizing plate according to any one of claims 1 to 4, which is a quadrangular shape in plan view. The polarizing plate according to any one of claims 1 to 5, wherein a separation film is laminated on the side of the protective film on which the polarizer is not laminated, and another protective film is laminated on the adhesive film. The side of the polarizer is not laminated, and a temporary protective film is laminated. An image display device comprising the polarizing plate according to any one of claims 1 to 5. In a method of producing a polarizing plate, a polarizer is laminated on a first protective film formed into a predetermined shape so that a whole surface of one surface is covered by the first protective film, and the polarizer is coated on the polarizer The second protective film is laminated on the inner side of at least a part of the protective film of at least one of the first protective film and the second protective film. In the embodiment, the first protective film, the polarizer, and the second protective film are laminated.