JP7018272B2 - Polarizing plate and liquid crystal display device - Google Patents

Description

The present invention relates to a polarizing plate and a liquid crystal display device.

In recent years, liquid crystal panels for liquid crystal displays have been required to be thinner. Since the polarizing element used in the liquid crystal panel is generally brittle and easily torn, protective films are attached to both sides of the polarizing element to form a polarizing plate, and this is attached to the liquid crystal cell. At this time, it is common to polish the end portion of the polarizing plate in order to improve the dimensional accuracy of the polarizing plate (see, for example, Patent Document 1).

A pressure-sensitive adhesive is usually used to attach the polarizing plate to the liquid crystal cell. That is, a separator (release film) is attached to the unused polarizing plate via a pressure-sensitive pressure-sensitive adhesive layer (see, for example, Patent Document 2), and the separator is peeled off when the polarizing plate is used to obtain a pressure-sensitive pressure-sensitive adhesive. The layer is exposed, and the polarizing plate is attached to the liquid crystal cell with the surface facing the liquid crystal cell.

Further, the polarizing plate may be provided with an optical functional film other than the polarizing element, and a pressure-sensitive pressure-sensitive adhesive may be used for bonding the polarizing element to the other optical functional film (for example, Patent Document). 3).

Japanese Patent No. 5743291 Japanese Unexamined Patent Publication No. 11-254550 Japanese Patent No. 3875331

Due to the demand for further thinning of the liquid crystal panel, a polarizing plate in which a protective film is bonded to only one side of the polarizing element is being developed. However, a polarizing plate having a protective film bonded to only one side of the polarizing element tends to have cracks in the polarizing element during a durability test.

Further, from the viewpoint of design, it is desirable that the liquid crystal display has a narrow frame, and therefore, the polarizing plate is required to have high dimensional accuracy. When polishing the end of a polarizing plate to obtain high dimensional accuracy, a polarizing plate in which a protective film is attached to only one side of the polarizing element causes a large amount of damage to the polarizing element during polishing, and the end face of the polarizing element becomes rough. There is a tendency for cracks to easily form in the polarizing element during the durability test.

Therefore, an object of the present invention is to provide a polarizing plate having a protective film on only one side of the polarizing element, which is less likely to crack during a durability test. Another object of the present invention is to provide a liquid crystal display device provided with the polarizing plate.

The present invention is a polarizing plate including a polarizing element and a protective film laminated on only one surface of the polarizing element, and the end face of the polarizing element and the end face of the protective film are in the thickness direction of the polarizing plate. The end face of the polarizing element provides a polarizing plate located inside the end face of the protective film.

In this polarizing plate, the end face of the polarizing element and the end face of the protective film are inclined with respect to the thickness direction of the polarizing plate, and the end face of the polarizing element is located inside the end face of the protective film. Therefore, the end face of the polarizing element is less likely to be exposed to physical stimuli from the external environment. Therefore, this polarizing plate is less likely to crack during the durability test.

This polarizing plate may be further provided with a pressure-sensitive pressure-sensitive adhesive layer laminated on the surface opposite to the side on which the protective film for the polarizing element is laminated, and further via the pressure-sensitive pressure-sensitive adhesive layer. It may further include a laminated optical functional film. According to this, it is possible to obtain a polarizing plate having a further optical function with respect to a polarizing plate provided with a polarizing element and a protective film.

The end face of the optical functional film is preferably located outside the end face of the polarizing element. According to this, the end face of the stator is further protected from physical stimuli from the external environment.

The optical functional film may be a reflective polarizing element.

The present invention also provides a liquid crystal display device provided with the above-mentioned polarizing plate. Even when a liquid crystal display device in which the above-mentioned polarizing plate is attached to a liquid crystal cell or the like is configured, the end face of the polarizing element is less likely to be exposed to physical stimuli from the external environment.

According to the present invention, it is possible to provide a polarizing plate having a protective film on only one side of the polarizing element, which is less likely to crack during a durability test. Further, it is possible to provide a liquid crystal display device provided with the polarizing plate.

It is a perspective view of the polarizing plate of one Embodiment of this invention. (A) is a cross-sectional view taken along the line IIa-IIa of FIG. (B) is a cross-sectional view taken along the line IIb-IIb of FIG. It is an enlarged view of the edge part of a polarizing film and a protective film. It is sectional drawing of the polarizing plate of another embodiment of this invention. It is sectional drawing of the polarizing plate of another embodiment of this invention. It is sectional drawing of the liquid crystal display device. It is a side view of a cutting tool. It is a front view of a cutting tool. It is a figure which shows the end shape of the polarizing plate produced in Example 1. FIG. It is a figure which shows the end shape of the polarizing plate produced in Example 2. FIG. It is a figure which shows the end shape of the polarizing plate produced in the comparative example 1. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same parts or corresponding parts are designated by the same reference numerals, and duplicate description will be omitted. In addition, the dimensional ratio of each drawing does not always match the actual one, and in particular, the thickness is exaggerated.

<Polarizer>
As shown in FIGS. 1 to 3, in the polarizing plate 1 of the present embodiment, the protective film 3 is laminated on one side of the polarizing film (polarizer) 2 formed in the form of a thin film, and the protective film 3 is laminated on the other side. Is laminated with a reflective polarizing element 4 via a pressure-sensitive pressure-sensitive adhesive layer 5. The polarizing film 2, the protective film 3, and the reflective polarizing element 4 are all formed into a rectangular shape in a plan view, and this shape is also the external shape of the polarizing plate 1.

The polarizing plate 1 is attached to one side or both sides of a display cell (image display element) such as a liquid crystal cell. The polarizing plate 1 is preferably attached to the back surface side of the display cell. The polarizing plate on the back side is more likely to cause dew condensation than the polarizing plate on the visual recognition side, and cracks are more likely to occur in the polarizing film. However, according to the polarizing plate 1 of the present embodiment, cracks are significantly suppressed in the polarizing film 2. can do.

The end face 2a of the polarizing element 2 and the end face 3a of the protective film 3, which are components of the end face 1a of the polarizing plate 1, are inclined with respect to the thickness direction of the polarizing plate 1, and the end face 2a of the polarizing film 2 is the protective film 3. It is located inside the end surface 3a of the polarizing plate 1 (center side of the main surface of the polarizing plate 1). In other words, of the sides constituting the end surface 2a of the polarizing film 2, the side 2b located on the side far from the protective film 3 and perpendicular to the thickness direction of the polarizing plate 1 (see FIG. 3; hereinafter, simply "end side 2b"". The side 3b (see FIG. 3; hereinafter, simply "end side") is located on the side far from the polarizing film 2 and perpendicular to the thickness direction of the polarizing plate 1 among the sides constituting the end surface 3a of the protective film 3. It is located inside "3b".

The end surface 2a of the polarizing film 2 and the end surface 3a of the protective film 3 form substantially the same plane (so-called flush state), and the plane is in the thickness direction of the polarizing plate 1. It is tilted. The angle α (see FIG. 3) formed by the plane and the surface of the polarizing plate 1 is preferably 45 to 88 degrees. Here, the angle α can be obtained from the cross-sectional shape of the polarizing plate 1 obtained by a laser microscope, and more specifically, the tangent line and the protective film in contact with both the end face 3a of the protective film and the end face 2a of the polarizing film. It refers to the largest angle formed by the plane perpendicular to the thickness direction of No. 3 (see also FIG. 9).

Regarding the fact that the end side 2b is located inside the end side 3b, the distance L (see FIG. 3) between the two when the polarizing plate 1 is viewed in a plan view is preferably 1 to 100 μm. It is more preferably ~ 50 μm, and even more preferably 5-10 μm. When the end side 2b and the end side 3b have such a positional relationship, the effect of physically protecting the end surface 2a of the polarizing film 2 is particularly high, and a wide display surface can be secured even when a liquid crystal display is configured. can.

It is preferable that the end face 2a of the polarizing film 2 and the end face 3a of the protective film 3 have the above-mentioned relationship over the entire circumference of the polarizing plate 1. When the above relationship is established over the entire circumference of the polarizing plate 1, all the ends of the polarizing plate 1 are protected from physical stimuli.

As the material of the polarizing film 2, a known material conventionally used for producing a polarizing plate can be used. For example, a polyvinyl alcohol-based resin, a polyvinyl acetate resin, an ethylene / vinyl acetate (EVA) resin, and a polyamide can be used. Examples thereof include resins and polyester resins. Of these, polyvinyl alcohol-based resins are preferable. When the film is formed into a film for bonding with the protective film 3, it is preferable that the uniaxially stretched film is dyed with iodine or a dichroic dye, and then treated with boric acid.

The thickness of the polarizing film 2 is preferably 2 to 30 μm, more preferably 2 to 15 μm, and even more preferably 2 to 10 μm. Generally, the thinner the polarizing film, the easier it is for cracks to occur, but in the present embodiment, even if the polarizing film 2 is 10 μm or less, cracks can be significantly prevented.

The protective film 3 is a film that prevents cracks and scratches on the main surface and edges of the polarizing film 2. Here, the "protective film" refers to a film physically laminated at a position closest to the polarizing film 2 for the purpose of protecting the polarizing film 2, among various films that can be laminated on the polarizing film 2.

The protective film 3 can be made of various transparent resin films known in the field of polarizing plates. For example, a cellulose-based resin typified by triacetyl cellulose, a polyolefin-based resin typified by a polypropylene-based resin, a cyclic olefin-based resin typified by a norbornene-based resin, and an acrylic typified by a polymethylmethacrylate-based resin. Examples thereof include polyester-based resins and polyester-based resins typified by polyethylene terephthalate-based resins. Of these, cellulosic resins are typical. Here, "transparent" means that the visible light transmittance is 80% or more.

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

The lamination of the polarizing film 2 and the protective film 3 may be configured by laminating the polarizing film 2 and the protective film 3 formed in a film shape via an adhesive, and the protective film 3 may be laminated by a coating layer. It may be formed, or a solution of a material constituting the coating layer (for example, an adhesive described later) may be applied onto the polarizing film 2 and dried, or it may be formed by irradiating with active energy rays. The adhesive layer is not shown in FIGS. 1 to 3.

When an adhesive is used in laminating the polarizing film 2 and the protective film 3, various adhesives conventionally used for producing a polarizing plate can be used as the adhesive. For example, an epoxy resin containing no aromatic ring in the molecule is preferable from the viewpoint of weather resistance, refractive index, cationic polymerization, and the like. Further, those that are cured by irradiation with active energy rays (ultraviolet rays or heat rays) are preferable.

As the epoxy resin, for example, a hydrogenated epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin and the like are preferable. For epoxy resins, polymerization initiators (for example, photocationic polymerization initiators for polymerizing by ultraviolet irradiation, thermal cationic polymerization initiators for polymerization by heat ray irradiation), and other additives (sensitizers, etc.) Can be added to prepare and use an epoxy resin composition for coating.

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

The pressure-sensitive pressure-sensitive adhesive layer 5 can be made of an acrylic resin, a silicone-based resin, polyester, polyurethane, polyether, or the like.

The thickness of the pressure-sensitive pressure-sensitive adhesive layer 5 is preferably 2 to 500 μm, more preferably 2 to 200 μm, and even more preferably 2 to 50 μm.

As a method of laminating the pressure-sensitive adhesive layer 5 on the polarizing film 2, for example, a method of applying a solution containing the above resin or an arbitrary additive component to the polarizing film 2 may be used, and the solution may be felt on a separately prepared separator. A method of forming the pressure pressure-sensitive adhesive layer 5 and then transferring it onto the polarizing film 2 may also be used.

The separator is generally a peelable film that is attached for the purpose of protecting the pressure-sensitive adhesive layer and preventing the adhesion of foreign substances, and is peeled off when the polarizing plate 1 is used to expose the pressure-sensitive adhesive layer. .. The separator can be made of, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate, or the like. Of these, a stretched film of polyethylene terephthalate is preferable.

The thickness of the separator is preferably 2 to 500 μm, more preferably 2 to 200 μm, and even more preferably 2 to 100 μm.

As described above, the separator may be temporarily used in the manufacturing process of the polarizing plate 1, and remains as a part of the polarizing plate 1 until immediately before the polarizing plate 1 is attached to the liquid crystal cell or the like. You may.

Any one can be used as the reflective polarizing element 4. The end surface 4a of the reflective polarizing element 4 is inclined with respect to the thickness direction of the polarizing plate 1, and is inclined in the same direction at substantially the same angle (for example, within a range of ± 20 degrees) with the end surface 2a of the polarizing film 2. The edge of the reflective polarizing element 4 on the side close to the polarizing element 2 is located outside the edge 2b of the polarizing film 2 so as to protrude outward from the end of the polarizing film 2. That is, the end surface 4a of the reflective polarizing element 4 does not form the same plane as the end surface 2a of the polarizing film 2. In a plan view, the reflective polarizing element 4 preferably covers the entire surface of the polarizing film 2. The end face of such a form can be achieved, for example, by integrally laminating a reflective polarizing element 4 on a polarizing film 2 via a pressure-sensitive adhesive layer 5 and performing cutting described later. can.

The total thickness of the polarizing plate 1 including the polarizing film 2, the protective film 3, and the reflective polarizing element 4 is preferably 10 to 500 μm, more preferably 10 to 300 μm, and more preferably 10 to 200 μm. More preferred.

In the polarizing plate 1 described above, the end face 2a of the polarizing element 2 and the end face 3a of the protective film 3 are inclined with respect to the thickness direction of the polarizing plate 1, and the end face 2a of the polarizing film 2 is protected. Since it is located inside the end surface 3a of the film 3, the end surface 2a of the polarizing film 2 is less likely to be exposed to physical stimuli from the external environment. Therefore, the polarizing plate 1 is less likely to crack during the durability test.

Further, the polarizing plate 1 further includes a reflective polarizing element 4 via a pressure-sensitive pressure-sensitive adhesive layer 5 laminated on a surface opposite to the side on which the protective film 3 of the polarizing film 2 is laminated. Moreover, since the end surface 4a of the reflective polarizing element 4 is located outside the end surface 2a of the polarizing film 2, the end surface 2a of the polarizing film 2 is further protected from physical stimuli from the external environment.

The polarizing plate 1 of the present embodiment can be changed in configuration to another aspect. For example, as in the polarizing plate 1A shown in FIG. 4, the end face 4a of the reflective polarizing element 4 may not be tilted with respect to the thickness direction of the polarizing plate 1, and is shown in FIG. As in the case of the polarizing plate 1B, the embodiment may not include the reflective polarizing element 4.

Further, as shown in FIG. 6, for example, the polarizing plate 1 is placed on the back surface side (lower side in the drawing) of the liquid crystal cell 8 and is pressure-sensitive adhesive different from the pressure-sensitive pressure-sensitive adhesive layer 5 constituting the polarizing plate 1. A polarizing plate 1B having a pressure-sensitive pressure-sensitive adhesive layer 5 on the surface of the polarizing film 2 is attached to the visible side (upper side in the drawing) of the liquid crystal cell 8 to be attached using the agent layer 5. The liquid crystal display device 100 can be manufactured by combining the above with a backlight (surface light source device; not shown) and other members. The liquid crystal display device usually incorporates two polarizing plates, but the liquid crystal display device of the present embodiment may include at least one polarizing plate.

<How to cut the end of the polarizing plate>
The shape of the end portion of the polarizing plate 1 described above can be formed by cutting (polishing) the end portion of the polarizing plate as follows, for example.

First, about 100 polarizing plates obtained by laminating the polarizing film 2, the protective film 3, the pressure-sensitive pressure-sensitive adhesive layer 5, and the reflective polarizing element 4 as described above and cutting them into the same shape are prepared, and these are placed on the same surface in the same direction. Laminate them so that they face each other to form a polarizing plate laminate. Then, the end portion of this polarizing plate laminate is cut using the cutting tool described below.

As shown in FIGS. 7 and 8, the cutting tool 10 is a rotating body fixed to the support base 10a and rotatable about the rotation axis A. Although the cutting tool 10 is drawn as a disk shape in FIGS. 7 and 8, the cutting tool 10 is not limited to the shape. The rotation axis A extends in a direction orthogonal to the end face of the polarizing plate laminate to be machined.

The cutting tool 10 has an installation surface S perpendicular to the axis of rotation A (and thus parallel to the end face of the polarizing plate laminate to be machined). On the installation surface S, a first cutting portion group consisting of cutting portions 11a, 11b and 11c and a second cutting portion group consisting of cutting portions 11d, 11e and 11f are provided, and each cutting portion is provided. It has a cutting blade B for scraping off the end face. Each cutting portion is arranged around the axis of rotation A. Each cutting portion protrudes from the installation surface S toward the end surface of the polarizing plate laminate to be machined, and the cutting blade B is arranged on the top surface of the protruding cutting portion. The cutting blade B included in each cutting portion is usually arranged so as to extend parallel to the installation surface S (hence, the end surface of the polarizing plate laminate to be machined).

As shown in FIG. 8, when the cutting tools 11a, 11b and 11c constituting the first cutting section group are rotated in the rotation direction thereof (direction of the arrow shown in FIG. 8), the cutting tool 10 is rotated. In this order, it abuts on the end face of the polarizing plate laminate and cuts the end face. The cutting portions 11a, 11b and 11c are arranged so that the distance from the installation surface S to the cutting blade B (protruding height of the cutting blade B) becomes larger as the cutting portion is located on the downstream side in the rotation direction of the cutting tool 10. Have been placed. That is, the protruding height of the cutting blade B of the cutting portion 11b is larger than the protruding height of the cutting blade B of the cutting portion 11a, and the protruding height of the cutting blade B of the cutting portion 11c is the protruding height of the cutting blade B of the cutting portion 11b. Greater than height.

The same applies to the second cutting section group, and the cutting sections 11d, 11e and 11f constituting the second cutting section group are polarizing plates in this order when the cutting tool 10 is rotated in the rotation direction thereof. It abuts on the end face of the laminate and cuts the end face. The cutting portions 11d, 11e and 11f are arranged so that the protruding height of the cutting blade B becomes larger as the cutting portion is located on the downstream side in the rotation direction of the cutting tool 10. That is, the protruding height of the cutting blade B of the cutting portion 11e is larger than the protruding height of the cutting blade B of the cutting portion 11d, and the protruding height of the cutting blade B of the cutting portion 11f is the protruding height of the cutting blade B of the cutting portion 11e. Greater than height.

Further, as shown in FIG. 8, the cutting portions 11a, 11b and 11c constituting the first cutting portion group are located closer to the downstream side in the rotation direction of the cutting tool 10 from the rotation axis A. It is arranged so that the distance to the cutting blade B is short, that is, the distance from the rotation axis A to the cutting blade B in the cutting portion 11b is shorter than that in the cutting portion 11a, and the rotation axis A in the cutting portion 11c. The distance from the cutting blade B to the cutting blade B is shorter than that in the cutting portion 11b. The same applies to the second cutting section group, and the cutting sections 11d, 11e and 11f constituting the second cutting section group are such that the cutting section located on the downstream side in the rotation direction of the cutting tool 10 is the rotation axis A. It is arranged so that the distance from the cutting tool B to the cutting blade B is short. That is, the distance from the rotating shaft A to the cutting blade B in the cutting portion 11e is shorter than that in the cutting portion 11d, and the distance from the rotating shaft A to the cutting blade B in the cutting portion 11f is smaller than that in the cutting portion 11e. short.

It is preferable that the cutting portions arranged on the installation surface S are arranged around the rotation axis A at equal intervals from each other.

In the cutting tool 10, the cutting portions 11a, 11b, 11d, 11e other than the last cutting portion (cutting portion on the most downstream side in the rotation direction) in each cutting portion group are for rough cutting, and their cutting blades B are, for example, It can be composed of polycrystalline diamond. The final cutting portions 11c and 11f in each cutting portion group are for finishing, and the cutting blades B thereof can be made of, for example, single crystal diamond. However, the material of the cutting blade B is not limited to these.

The size of the cutting tool 10 is such that the diameter (shortest diameter) of the circle drawn by the cutting part by the rotation of the cutting tool 10 is the height of the polarizing plate laminate so that the end faces of all the stacked polarizing plates can be cut together. There are no particular restrictions as long as it is the same as or longer than.

When cutting the end portion of the polarizing plate laminate, the cutting tool 10 is rotated in the direction of the arrow in FIG. Move to make contact. At this time, as the vertical orientation of the polarizing plate laminate, the polarizing film 2 is oriented upward with respect to the protective film 3. The cutting tool 10 is designed so that it can cut from the upper side in the drawing toward the lower side and cannot cut from the lower side in the drawing toward the upper side in the rotation in the direction of the arrow in FIG. As a result, the edge of the polarizing plate laminate is always cut from the polarizing film 2 side toward the protective film 3 side.

During cutting, the pressing force due to the rotation of the cutting tool 10 acts on the end portion of the polarizing plate laminate, whereby the end portion of the polarizing plate laminate is tilted downward. By cutting the end portion in this state, each polarizing plate becomes a polarizing plate 1 having an inclined end face as shown in FIGS. 2 and 3.

In order to make it easier for the pressing force due to the rotation of the cutting tool 10 to tilt downward so that the end of the polarizing plate laminate hangs downward during cutting, a method of reducing the pressure of the clamp that sandwiches the polarizing plate laminate or polarization is used. A method of reducing the area of the clamp that sandwiches the plate laminate can be mentioned.

According to the above-mentioned cutting process, not only the end face of the polarizing plate can be tilted, but also there is an advantage that the dimensional accuracy is higher than that of the conventional cutting of the polarizing plate laminate by a laser.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

In the above embodiment, the reflective polarizing element 4 is shown as an optical functional film laminated on the polarizing film 2 via the pressure-sensitive pressure-sensitive adhesive layer 5, but instead of this, another film, for example, an uneven shape on the surface is shown. A film having an antiglare function; a film having a surface antireflection function; a reflection film having a reflection function on the surface; a semitransmissive reflection film having both a reflection function and a transmission function; a viewing angle compensating film may be used.

Further, an optical functional film may be provided on the protective film 3 side via a pressure-sensitive adhesive layer.

Further, in the above embodiment, the cutting tool 10 is used to form the end shape of the polarizing plate laminate, but other processing methods may be used as long as the end face of the polarizing plate can be inclined. For example, a method of cutting by hitting a flat plate-shaped blade diagonally may be adopted.

Hereinafter, the contents of the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

(1) Preparation of Polarizing Film A polyvinyl alcohol film having an average degree of polymerization of about 2400, a saponification degree of 99.9 mol% or more and a thickness of 20 μm was uniaxially stretched about 4 times by a dry method. After immersing in pure water at 40 ° C. for 1 minute while maintaining the tension of stretching, the mixture was immersed in an aqueous solution having 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 having a weight ratio of potassium iodide / boric acid / water of 10.5 / 7.5 / 100 at 68 ° C. for 300 seconds. Subsequently, the film was washed with pure water at 5 ° C. for 5 seconds and then dried at 70 ° C. for 180 seconds to obtain a polarizing film (polarizer) in which iodine was adsorbed and oriented on a uniaxially stretched polyvinyl alcohol film. The thickness of the polarizing film was 7 μm.

(2) Preparation of water-based adhesive Polyvinyl alcohol powder (trade name "KL-318" manufactured by Kuraray Co., Ltd., average degree of polymerization of 1800) is dissolved in hot water at 95 ° C. to prepare a polyvinyl alcohol aqueous solution having a concentration of 3% by weight. did. A cross-linking agent (trade name "Smiley's Resin 650" manufactured by Taoka Chemical Industry Co., Ltd.) was mixed with the obtained aqueous solution at a ratio of 1 part by mass with 2 parts by mass of polyvinyl alcohol powder to obtain a water-based adhesive.

(3) Preparation of single-sided protective polarizing plate A single-sided protective polarizing plate with a release film was prepared by the following procedure. The polarizing film obtained in (1) above is continuously conveyed, and the protective film is continuously unwound from a roll of a protective film (Zeon Corporation, Zeonoa film ZF14-023, thickness 23 μm). Was treated with corona. Further, the release film was continuously unwound from the roll of the release film (trade name "KC8UX2MW", which is a TAC film manufactured by Konica Minolta Opto Co., Ltd., thickness 80 μm, no saponification treatment).

Next, the water-based adhesive obtained in (2) above is injected between the polarizing film and the protective film, and pure water is injected between the polarizing film and the release film, and these are placed between a pair of bonding rolls. A laminated film composed of a protective film / water-based adhesive layer / polarizing film / pure water / release film was obtained. Subsequently, the laminated film is conveyed and heat-treated at 80 ° C. for 300 seconds through a drying device to dry the water-based adhesive layer and volatilize and remove the pure water interposed between the polarizing film and the release film. Then, a single-sided protective polarizing plate with a release film was obtained. The release film was peeled off from the single-sided protective polarizing plate with the release film to obtain a single-sided protective polarizing plate.

(4) Fabrication of Single-sided Protective Polarizing Plate with Brightness-Improved Film Brightness-enhancing film (reflective type manufactured by 3M) via an acrylic pressure-sensitive adhesive on the polarizing film surface of the single-sided protective polarizing plate obtained in (3) above. A single-sided protective polarizing plate with a brightness-improving film was obtained by laminating a polarizing element (trade name “APF”). At this time, the stretching axis of the luminance improving film was parallel to the stretching direction of the polarizing film and bonded.

(5) Manufacture of a polarizing plate with an acrylic pressure-sensitive adhesive The acrylic pressure-sensitive adhesive with a separator film is attached to the brightness-improving film surface of the single-sided protective polarizing plate with a brightness-improving film obtained in (4) above. A polarizing plate with an acrylic pressure-sensitive adhesive was obtained.

(6) End face cutting processing The acrylic pressure-sensitive pressure-sensitive adhesive-attached polarizing plate (hereinafter, simply referred to as “polarizing plate”) obtained in (5) above is cut into a size of 120 mm × 70 mm, and the polarizing plate after cutting is cut. 100 sheets were laminated with their four sides aligned to obtain a polarizing plate laminate. The polarizing plate laminate was sandwiched by a clamp having a main surface having an area slightly smaller than the area of the main surface of the polarizing plate laminate. When sandwiching the polarizing plate laminate, the pressure of the clamp was also adjusted. Next, all the end faces of all four sides are cut using the same cutting tool as the cutting tools shown in FIGS. 7 and 8 except that the first cutting part group and the second cutting part group each have five cutting parts. Processed (polishing). The cutting conditions for the end faces of the four sides were all the same.

The cutting tools used were arranged so that the protruding height of the cutting blade B became larger as the cutting parts located on the downstream side in the rotation direction of the cutting tool had five cutting parts in each cutting part group. Is. Further, the five cutting portions are arranged so that the distance from the rotation axis A to the cutting blade B becomes shorter as the cutting portion is located on the downstream side in the rotation direction of the cutting tool. Each of the cutting portions constituting the first cutting portion group and the second cutting portion group is arranged around the rotation axis at equal intervals, and cuts at positions facing each other via the rotation axis. Two cutting portions having the same protrusion height of the blade and the distance from the rotation to the cutting blade are arranged.

Specifically, by rotating the cutting tool around their rotation axis A and horizontally moving the polarizing plate laminate while the position of the cutting tool is fixed, the length direction of the end face of the polarizing plate laminate is obtained. The cutting tool was relatively moved with respect to the laminated body of the polarizing plate, and the cutting blades of each cutting portion were brought into contact with the two facing end faces, and these end faces were simultaneously scraped off. The relative movement was performed from one end to the other end of the end face. By this one relative movement, five stages of cutting were performed by five types of cutting portions having different protrusion heights of the cutting blades.

After cutting, a 3D measuring laser microscope (OLS4100 manufactured by Olympus Corporation) was used to observe the end portion of the polarizing plate, and the degree of inclination of the end face was confirmed.

(7) Heat shock test A heat shock test was conducted as a durability test. A sample for the heat shock test was prepared by the following procedure.

After attaching the end face polishing sample obtained in (6) above to a non-alkali glass plate (“Eagle-XG” manufactured by Corning Inc.), pressurize for 20 minutes under the conditions of a temperature of 50 ° C. and a pressure of 5 MPa in an autoclave. The treatment was continued, and the mixture was left to stand for one day in an atmosphere having a temperature of 23 ° C. and a relative humidity of 60%. After that, using a cold shock tester "TSA-301L-W" manufactured by ESPEC CORPORATION, the low temperature side was -40 ° C [holding time 30 minutes], the room temperature was 23 ° C [holding time 5 minutes], and the high temperature side was 85 ° C [holding time]. A durability test was conducted in which the inside of the test tank was stored for 12 cycles under the conditions set to change in the order of [30 minutes]. After that, the sample was taken out, and the edge of the sample was confirmed by using an optical microscope (VHX-5000, manufactured by KEYENCE CORPORATION) to check for crack-like appearance defects, and the polarizing film existing around the edge of the polarizing plate 10 mm was confirmed. The number of cracks was calculated.

(8) Examples and Comparative Examples The results of performing "(6) end face cutting" and "(7) heat shock test" on the polarizing plates manufactured according to the above procedures (1) to (5) are shown below. show.

[Example 1]
100 polarizing plates are laminated, and the polarizing film is placed on the upper side of the protective film and set in a cutting machine. Cutting is performed so that the end face is cut from the polarizing film side to the protective film side. Processing was performed. As a result of cutting, the end face of the polarizing plate is tilted with respect to the thickness direction of the polarizing plate, and the end surface of the polarizing film opposite to the bonding surface with the protective film is on the side far from the polarizing film of the protective film. It was 6 μm inside the edge of the. FIG. 9 shows the shape of the end of the polarizing plate confirmed by the 3D measurement laser microscope. When the heat shock test was carried out, no cracks were observed on the polarizing film.

[Example 2]
The end face cutting process was carried out in the same manner as in Example 1 except that triacetyl cellulose (manufactured by Konica Minolta Opto Co., Ltd., zero tack, thickness 20 μm) obtained by saponifying the protective film was used. As a result of cutting, the end face of the polarizing plate is tilted with respect to the thickness direction of the polarizing plate, and the end surface of the polarizing film opposite to the bonding surface with the protective film is on the side far from the polarizing film of the protective film. It was 9 μm inside from the edge of. The shape of the end of the polarizing plate confirmed by the 3D measurement laser microscope is shown in FIG. When the heat shock test was carried out, no cracks were observed on the polarizing film.

[Comparative Example 1]
A polarizing plate was cut in the same manner as in Example 1 except that the polarizing film was placed on the lower side of the protective film and the polarizing film was set in the cutting device. That is, the end face is cut from the protective film side toward the polarizing film side. As a result of cutting, the end face of the polarizing plate is tilted with respect to the thickness direction of the polarizing plate, and the end surface of the polarizing film opposite to the bonding surface with the protective film is on the side far from the polarizing film of the protective film. It was 11 μm outside the edge of. FIG. 11 shows the shape of the end of the polarizing plate confirmed by the 3D measurement laser microscope. When the heat shock test was carried out, 71 cracks were observed in the polarizing film.

The present invention can be used, for example, as a component of a liquid crystal panel.

1,1A, 1B ... Polarizing plate, 1a ... End face of polarizing plate, 2 ... Polarizing film (polarizer), 2a ... End face of polarizing film, 2b ... Edge edge of polarizing film, 3 ... Protective film, 3a ... Protective film End face, 3b ... End edge of protective film, 4 ... Reflective polarizing element (optical functional film), 4a ... End face of reflective polarizing element, 5 ... Pressure-sensitive pressure-sensitive adhesive layer, 100 ... Liquid crystal display device.

Claims (4)

A polarizing plate comprising a polarizing element and a protective film laminated on only one surface of the polarizing element.
The end face of the polarizing element and the end face of the protective film have an inclination with respect to the thickness direction of the polarizing plate.
The end face of the stator is located inside the end face of the protective film.
Further provided with a pressure-sensitive adhesive layer laminated on the surface of the polarizing element opposite to the side on which the protective film is laminated is provided.
Further, an optical functional film laminated via the pressure-sensitive adhesive layer is further provided.
The end face of the optical functional film is located outside the end face of the polarizing element.
A polarizing plate having a thickness of 2 to 10 μm. A polarizing plate comprising a polarizing element and a protective film laminated on only one surface of the polarizing element.
The end face of the polarizing element and the end face of the protective film have an inclination with respect to the thickness direction of the polarizing plate.
The end face of the stator is located inside the end face of the protective film.
Further provided with a pressure-sensitive adhesive layer laminated on the surface of the polarizing element opposite to the side on which the protective film is laminated is provided.
Further, an optical functional film laminated via the pressure-sensitive adhesive layer is further provided.
The optical functional film is a reflective polarizing element and is
A polarizing plate having a thickness of 2 to 10 μm. The polarizing plate according to claim 2, wherein the end face of the optical functional film is located outside the end face of the polarizing element. A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 3.

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