KR20170134220A - Polarizing plate and liquid crystal display device - Google Patents

Abstract

Provided is a polarizing plate which includes a protection film on one side of a polarizer and prevents a crack from occurring in an endurance test. The polarizing plate (1) includes the polarizer (2) and the protection film (3) stacked on any one side of the polarizer (2). An end side (2a) of the polarizer (2) and an end side (3a) of the protection film (3) have a slope with regard to a thickness direction of the polarizing plate (1). The end side (2a) of the polarizer (2) is located to be inner than the end side (3a) of the protection film (3). The end side (2a) of the polarizer (2) is difficult to be exposed to a physical stimulus from an external environment by the shape of the end side.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a polarizing plate,

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

In recent years, liquid crystal panels for liquid crystal displays have been required to be thinner. Polarizers used in liquid crystal panels are generally fragile and prone to tearing. To protect them, a polarizing plate is formed by bonding a protective film to both surfaces of a polarizer, and the polarizer is bonded to the liquid crystal cell. In this case, in order to increase the dimensional accuracy of the polarizing plate, the end of the polarizing plate is generally polished (see, for example, Patent Document 1).

A pressure-sensitive adhesive is usually used to adhere the polarizing plate to the liquid crystal cell. That is, a separator (peeling film) is bonded to an unused polarizing plate through a pressure sensitive adhesive layer (see, for example, Patent Document 2), and when the polarizing plate is used, the separator is peeled off to expose the pressure sensitive adhesive layer, The polarizing plate is bonded to the liquid crystal cell.

The polarizing plate may have another optical function film other than the polarizer, and a pressure sensitive adhesive may be used for bonding the polarizer and another optical function film (see, for example, Patent Document 3).

Patent Document 1: Japanese Patent No. 5743291 Patent Document 2: JP-A-11-254550 Patent Document 3: Japanese Patent No. 3875331

In response to a demand for making the liquid crystal panel thinner, a polarizing plate in which a protective film is bonded to only one side of the polarizer has been developed. However, a polarizing plate in which a protective film is bonded to only one side of the polarizer tends to cause cracks in the polarizer during the endurance test.

In view of design, the liquid crystal display preferably has a narrow frame, and therefore, a high dimensional accuracy is required for the polarizing plate. In the case of polishing the end portion of the polarizing plate to obtain high dimensional accuracy, in the polarizing plate formed by bonding a protective film to only one side of the polarizing plate, the damage to the polarizing plate at the time of polishing is large and the end face of the polarizing plate is rough, There is a tendency that cracks tend to occur.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a polarizing plate having a protective film on only one side of a polarizer, and which is less prone to cracking during the endurance test. Another object of the present invention is to provide a liquid crystal display device having the polarizing plate.

The present invention relates to a polarizing plate comprising a polarizer and a protective film laminated on only one side of the polarizer, wherein the end face of the polarizer and the end face of the protective film have a slope with respect to the thickness direction of the polarizer, Is provided inside the end face of the protective film.

In this polarizing plate, since the end face of the polarizer and the end face of the protective film have an inclination with respect to the thickness direction of the polarizing plate, and the end face of the polarizing film is located inside the end face of the protective film, It is difficult to be exposed to physical stimulation from the environment. Therefore, the polarizing plate is hardly cracked during the endurance test. It is preferable that the polarizing plate is a piece of product (sheet product) having an area of 100 square millimeters to 96000 square millimeters cut off from a long polarizing plate roll.

The polarizing plate may further include a pressure sensitive adhesive layer laminated on a surface opposite to the side where the protective film of the polarizer is laminated or may further include an optical function film laminated through the pressure sensitive adhesive layer . According to this, the polarizing plate having the polarizer and the protective film can be made a polarizing plate to which an optical function is further imparted.

It is preferable that the end face of the optical function film is located outside the end face of the polarizer.

According to this, the end face of the polarizer is further protected from physical stimulation from the external environment.

The optical function film may be a reflection type polarizer.

Further, the present invention provides a liquid crystal display device comprising the polarizing plate. Even when a liquid crystal display device in which the polarizing plate is adhered to a liquid crystal cell or the like is formed, the end face of the polarizer is hardly exposed to physical stimulation 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 a polarizer, which is less prone to cracking during the endurance test. Further, a liquid crystal display device having the polarizing plate can be provided.

1 is a perspective view of a polarizing plate according to an embodiment of the present invention.
2 (A) is a cross-sectional view taken along line IIa-IIa of FIG. (B) is a cross-sectional view taken along line IIb-IIb of FIG.
3 is an enlarged view of an end portion of the polarizing film and the protective film.
4 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.
5 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.
6 is a cross-sectional view of the liquid crystal display device.
7 is a side view of the cutting tool.
8 is a front view of the cutting tool.
9 is a view showing an end shape of the polarizing plate produced in Example 1. Fig.
10 is a view showing an end shape of the polarizing plate produced in Example 2. Fig.
11 is a view showing an end shape of the polarizing plate produced in Comparative Example 1. Fig.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios of the respective drawings do not always coincide with actual ones, and in particular, the thickness ratios are exaggerated.

<Polarizer>

As shown in Figs. 1 to 3, the polarizing plate 1 of the present embodiment has a protective film 3 laminated on one side of a polarizing film (polarizer) 2 formed in a thin film shape, And the reflective polarizer 4 is laminated via the pressure-sensitive adhesive layer 5. The polarizing film 2, the protective film 3 and the reflective polarizer 4 are all formed into a rectangular shape in plan view, and this shape also serves as an outer shape of the polarizing plate 1. [

The polarizing plate 1 is bonded to one surface or both surfaces of a display cell (image display device) such as a liquid crystal cell. It is preferable that the polarizing plate 1 is bonded to the back side of the display cell. The polarizing plate on the back side tends to cause condensation and the like more easily than the polarizing plate on the viewing side and cracks easily occur in the polarizing film. Therefore, according to the polarizing plate 1 of the present embodiment, the occurrence of cracks in the polarizing film 2 is remarkably suppressed .

The end face 2a of the polarizer 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, The end face 2a of the polarizing film 2 is located inside the end face 3a of the protective film 3 (the center side of the main face of the polarizing plate 1). 3) perpendicular to the thickness direction of the polarizing plate 1 (refer to FIG. 3), which is located farther from the protective film 3 than the side constituting the end face 2a of the polarizing film 2, Of the polarizing plate 1 is positioned on the side farther from the polarizing film 2 than the side constituting the end face 3a of the protective film 3 and the side 3b perpendicular to the thickness direction of the polarizing plate 1 (Hereinafter referred to simply as &quot; end side 3b &quot;) (see Fig.

The end face 2a of the polarizing film 2 and the end face 3a of the protective film 3 constitute substantially the same plane as each other As shown in Fig. The angle? (See FIG. 3) between the plane and the plane of the polarizing plate 1 is preferably 45 to 88 degrees. Here, the angle? Can be obtained from the cross-sectional shape of the polarizing plate 1 obtained by a laser microscope. More specifically, the angle? Is a tangential line which is in contact with both the end face 3a of the protective film and the end face 2a of the polarizing film And the angle formed by the surface perpendicular to the thickness direction of the protective film 3 (see Fig. 9).

The distance L (see FIG. 3) between the both sides of the polarizing plate 1 when the polarizing plate 1 is viewed from a plane is preferably 1 to 100 占 퐉 with respect to the case where the polarizing plate 1 is located on the inner side with respect to the end side 3b, More preferably from 3 to 50 mu m, and even more preferably from 5 to 10 mu m. When the end side 2b and the end side 3b are in this positional relationship, the effect of physically protecting the end face 2a of the polarizing film 2 is particularly high, and even when the liquid crystal display is constituted, can do.

It is preferable that the end face 2a of the polarizing film 2 and the end face 3a of the protective film 3 are in the above-described relationship over the entire circumference of the polarizing plate 1. [ If the above relationship is established over the entire periphery 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, known materials conventionally used in the production of a polarizing plate can be used, and examples thereof include a polyvinyl alcohol resin, a polyvinyl acetate resin, an ethylene / vinyl acetate (EVA) resin, And polyester-based resins.

Among them, a polyvinyl alcohol-based resin is preferable. In the case of molding in the form of 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 탆, more preferably 2 to 15 탆, and even more preferably 2 to 10 탆. Generally, a thinner polarizing film tends to cause a crack. In the present embodiment, however, even if the polarizing film 2 is 10 m or less, it is possible to prevent a significant crack.

The protective film 3 is a film for preventing cracks or damage on the main surface or the end of the polarizing film 2. Here, "protective film" refers to a film that is physically laminated at a position closest to the polarizing film 2 for the purpose of protecting the polarizing film 2, among the films that can be variously laminated on the polarizing film 2 .

The protective film 3 can be composed of various transparent resin films known in the field of polarizing plate. Examples thereof include cellulose resins typified by triacetylcellulose, polyolefin-based resins exemplified by polypropylene-based resins, cyclic olefin-based resins exemplified by norbornene-based resins, and polymethylmethacrylate-based resins Acrylic resin, polyethylene terephthalate resin, polyester resin, and the like. Among them, a cellulose-based resin is typical. The term &quot; transparent &quot; means that the visible light transmittance is 80% or more.

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

The lamination of the polarizing film 2 and the protective film 3 may be carried out by bonding the polarizing film 2 and the protective film 3 formed in the form of a film to each other through an adhesive, Or may be formed by coating a solution of a material constituting the coating layer (for example, an adhesive described below) on the polarizing film 2 and drying or irradiating an active energy ray. In Figs. 1 to 3, the adhesive layer is not shown.

When an adhesive is used in the lamination of the polarizing film 2 and the protective film 3, various adhesives conventionally used in the production of a polarizing plate can be used as the adhesive. For example, from the viewpoints of weatherability, refractive index, cationic polymerizability, and the like, an epoxy resin containing no aromatic ring in the molecule is preferable. Further, it is preferable to cure by irradiation with an active energy ray (ultraviolet ray or heat ray).

As the epoxy resin, for example, a hydrogenated epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin and the like are preferable. (For example, a cationic polymerization initiator for polymerization by irradiation with ultraviolet rays, a thermal cationic polymerization initiator for polymerization by irradiation of heat rays) and other additives (such as a sensitizer) are further added to the epoxy resin to prepare an epoxy A resin composition may be prepared and used.

As the adhesive, a composition containing an acrylic resin such as acrylamide, acrylate, urethane acrylate, and epoxy acrylate, or an aqueous adhesive including a polyvinyl alcohol resin may be used.

The pressure-sensitive adhesive layer (5) can be composed of acrylic resin, silicone resin, polyester, polyurethane, polyether, or the like.

The thickness of the pressure-sensitive adhesive layer (5) is preferably 2 to 500 占 퐉, more preferably 2 to 200 占 퐉, and still more preferably 2 to 50 占 퐉.

As a method for laminating the pressure-sensitive adhesive layer 5 on the polarizing film 2, for example, a method of applying a solution containing the resin or an arbitrary additive component to the polarizing film 2 may be applied, Pressure sensitive adhesive layer 5 may be formed of a solution and then transferred onto the polarizing film 2. [

The separator is generally a peelable film adhered for the purpose of protecting the pressure-sensitive adhesive layer or preventing adhesion of foreign matter, etc., and is peeled off when the polarizing plate 1 is used to expose the pressure-sensitive adhesive layer. The separator can be composed of, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate. Among them, a stretched film of polyethylene terephthalate is preferable.

The thickness of the separator is preferably 2 to 500 占 퐉, more preferably 2 to 200 占 퐉, and still more preferably 2 to 100 占 퐉.

The separator may be temporarily used in the manufacturing process of the polarizing plate 1 as described above or may remain as a part of the polarizing plate 1 until immediately before the polarizing plate 1 is bonded to the liquid crystal cell or the like.

As the reflective polarizer 4, any one can be used. The end face 4a of the reflection type polarizing element 4 is inclined with respect to the thickness direction of the polarizing plate 1 and is substantially at the same angle as the end face 2a of the polarizing film 2 It is inclined in the same direction. The end side closer to the polarizer 2 in the reflection type polarizing element 4 is located outside the end side 2b of the polarizing film 2 so as to protrude outward from the end of the polarizing film 2 . That is, the end face 4a of the reflection type polarizing element 4 does not have the same plane as the end face 2a of the polarizing film 2. It is preferable that the reflection type polarizing element 4 covers the entire surface of the polarizing film 2 in plan view. This type of end face can be achieved by integrally performing the cutting as described below, for example, when the reflective polarizer 4 is laminated on the polarizing film 2 through the pressure sensitive adhesive layer 5.

The total thickness of the polarizing plate 1 including the polarizing film 2, the protective film 3 and the reflective polarizer 4 is preferably 10 to 500 占 퐉, more preferably 10 to 300 占 퐉, And more preferably 200 m.

The polarizing plate 1 described above has a configuration in which the end face 2a of the polarizer 2 and the end face 3a of the protective film 3 are inclined with respect to the thickness direction of the polarizing plate 1, The end face 2a of the polarizing film 2 is located inside the end face 3a of the protective film 3 so that the end face 2a of the polarizing film 2 is hardly exposed to a physical stimulus from the external environment . Therefore, the polarizing plate 1 is hardly cracked at the endurance test.

The polarizing plate 1 further comprises a reflective polarizer 4 through a pressure sensitive adhesive layer 5 laminated on a surface of the polarizing film 2 opposite to the side on which the protective film 3 is laminated Since the end face 4a of the polarizing film 2 is located outside the end face 2a of the polarizing film 2, Lt; / RTI &gt;

The polarizing plate 1 of the present embodiment can be changed to another mode by changing its configuration. For example, the end face 4a of the reflection type polarizing element 4 may not be inclined with respect to the thickness direction of the polarizing plate 1 as in the polarizing plate 1A shown in Fig. 4, The polarizing plate 1B may be provided with no reflective polarizer 4 as in the polarizing plate 1B.

6, for example, the polarizing plate 1 is placed on the back side (lower side) of the liquid crystal cell 8 with a pressure-sensitive adhesive layer 5, which is separate from the pressure-sensitive adhesive layer 5 constituting the polarizing plate 1, Sensitive adhesive layer 5 and a polarizing plate 1B having a pressure sensitive adhesive layer 5 on the polarizing film 2 side is adhered to the viewing side (upper side in the drawing) of the liquid crystal cell 8 The liquid crystal display device 100 can be manufactured by constructing the liquid crystal panel 9 and combining a backlight (a planar light source device; not shown) and other members. Although two polarizing plates are normally inserted into a liquid crystal display device, at least one polarizing plate may be provided as the liquid crystal display device of the present embodiment.

&Lt; Cutting method of the end portion of the polarizing plate &

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

First, about 100 polarizing plates were prepared by laminating the polarizing film 2, the protective film 3, the pressure-sensitive adhesive layer 5, and the reflective polarizer 4 as described above and cut in the same manner, Direction to form a polarizing plate laminate. Then, the end portion of the polarizing plate laminate is cut using a cutting tool described below.

As shown in Figs. 7 and 8, the cutting tool 10 is a rotatable body fixed to a support table 10a and rotatable about an axis of rotation A as an axis. In Figs. 7 and 8, the cutting tool 10 is depicted as a disk, but the shape is not limited thereto. The rotating shaft A extends in a direction orthogonal to the end face of the polarizing plate laminate to be cut.

The cutting tool 10 has an installation surface S perpendicular to the rotation axis A (and thus parallel to the end surface of the polarizing plate laminate to be cut). On the mounting surface S, there are provided a first cutting portion group composed of the cutting portions 11a, 11b and 11c and a second cutting portion group composed of the cutting portions 11d, 11e and 11f, And a cutting edge (B) for cutting off the cutting edge (B). Each cutting portion is disposed around the rotation axis A. Each cutting portion protrudes from the mounting surface S toward the end face of the polarizing plate laminate to be cut and the cutting edge B is disposed on the top face of the protruding cut portion. The cutting edge B of each cutting portion is normally arranged so as to extend in parallel to the mounting surface S (and thus the end face of the polarizing plate laminate to be cut).

As shown in Fig. 8, the cutting portions 11a, 11b, and 11c constituting the first cutting portion group are configured such that when the cutting tool 10 is rotated in the rotating direction (the arrow direction shown in Fig. 8) The end face of the polarizing plate laminate is contacted in this order to cut the end face. The cutting portions 11a, 11b, and 11c are formed such that the distance from the mounting surface S to the cutting edge B (the cutting edge B (I.e., the protruding height of the protruding portion). That is, the protruding height of the cutting edge B of the cutting portion 11b is larger than the protruding height of the cutting edge B of the cutting portion 11a and the protruding height of the cutting edge B of the cutting portion 11c is larger than the protruding height of the cutting edge 11b Is greater than the projecting height of the cutting edge (B) of the portion (11b).

The cutting sections 11d, 11e and 11f constituting the second cutting section group are arranged in the order of the rotation of the cutting tool 10 in the rotating direction thereof, And the end face is cut by contacting the end face. The cutting portions 11d, 11e, and 11f are arranged so that the projecting height of the cutting edge B becomes larger as the cutting portion located on the downstream side in the rotational direction of the cutting tool 10 becomes larger. That is, the protruding height of the cutting edge B of the cutting portion 11e is larger than the protruding height of the cutting edge B of the cutting portion 11d, and the protruding height of the cutting edge B of the cutting portion 11f is larger than the protruding height of the cutting edge B, Is larger than the projecting height of the cutting edge (B) of the portion (11e).

As shown in Fig. 8, the cutting portions 11a, 11b and 11c constituting the first cutting portion group are arranged such that the cutting portion located on the downstream side in the rotational direction of the cutting tool 10, The distance from the rotation axis A to the cutting edge B in the cutting portion 11b is set so that the distance from the cutting edge 11a to the cutting edge 11a is shorter than the distance from the cutting edge 11a to the cutting edge B, And the distance from the rotation axis A to the cutting edge B at the cutting portion 11c is shorter than that at the cutting portion 11b. The cutting portions 11d, 11e and 11f constituting the second cutting portion group are arranged such that the cutting portions located on the downstream side in the rotational direction of the cutting tool 10 are arranged so that the rotational axis A ) To the cutting edge B is shortened. That is, the distance from the rotation axis A to the cutting edge B in the cutting portion 11e is shorter than that in the cutting portion 11d, and the distance from the rotation axis A in the cutting portion 11f to the cutting edge B Is shorter than that at the cutting portion 11e.

The cutting portions arranged on the mounting surface S are preferably arranged around the rotating shaft A at equal intervals.

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

The size of the cutting tool 10 is set such that the diameter (shortest diameter) of the cut portion drawn by the rotation of the cutting tool 10 (the shortest diameter) is the same as that of the polarizer plate laminate And is not particularly limited as long as it is equal to or greater than the height.

When the end of the polarizing plate laminate is cut, the cutting tool 10 is rotated in the direction of the arrow in FIG. 8 so that the direction perpendicular to the stacking direction of the polarizing plate stacks is the approach direction and the both are relatively moved . At this time, in the direction of the up-and-down direction 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 cutting can be performed from the upper side of the drawing to the lower side in the rotation in the direction of the arrow in Fig. 8, and the cutting tool 10 can not be cut from the lower side toward the upper side. As a result, the polarizing plate laminate always carries out cutting of the end portion from the polarizing film 2 side toward the protective film 3 side.

During cutting, an urging force by the rotation of the cutting tool 10 acts on the end portion of the polarizing plate laminate, thereby tilting the end portion of the polarizing plate laminate so as to be drained toward the lower side. By cutting off the end portion in this state, each of the polarizing plates becomes a polarizing plate 1 whose end face is inclined as shown in Figs. 2 and 3.

In order to make it easier for the pressing force by the rotation of the cutting tool 10 to be inclined toward the lower side of the polarizing plate laminate during cutting, the pressure of the clamp for sandwiching the polarizing plate laminate may be lowered, And a method of reducing the area of the clamping portion.

According to the cutting process, not only the end face of the polarizing plate can be inclined but also the dimensional accuracy is higher than that of cutting the polarizing plate laminate by the laser, which has been conventionally done.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments at all.

In the above embodiment, the reflective polarizer 4 is shown as an optical function film laminated to the polarizing film 2 through the pressure-sensitive adhesive layer 5. Instead of this, another film, for example, Films with antiglare function; A film having a surface antireflection function; A reflecting film having a reflecting function on the surface; A transflective film having both a reflective function and a transmissive function; It may be a viewing angle compensation film.

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

In the above embodiment, the cutting tool 10 is used to form the end portion 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 obliquely cutting a flat blade may be adopted.

[Example]

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. The present invention is not limited to the following examples.

(1) Production of polarizing film

A polyvinyl alcohol film having an average degree of polymerization of about 2,400, a degree of saponification of 99.9 mol% or more and a thickness of 20 탆 was uniaxially stretched by about 4 times in a dry manner. Immersed in pure water at 40 DEG C for 1 minute while maintaining the stretched state, and then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.1 / 5/100 at 28 DEG C for 60 seconds. Thereafter, 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 占 폚 for 5 seconds and then dried at 70 占 폚 for 180 seconds to obtain a polarizing film (polarizer) in which iodine was adsorbed and oriented on the uniaxially stretched polyvinyl alcohol film. The thickness of the polarizing film was 7 탆.

(2) Preparation of waterborne adhesives

A polyvinyl alcohol aqueous solution having a concentration of 3% by weight was prepared by dissolving polyvinyl alcohol powder (trade name "KL-318" manufactured by Kuraray Co., Ltd., average degree of polymerization: 1800) in hot water at 95 ° C. A crosslinking agent (trade name "SUMIRESIN 650" manufactured by DAOKA CHEMICAL INDUSTRIES, LTD.) Was mixed at a ratio of 1 part by mass with respect to 2 parts by mass of polyvinyl alcohol powder to obtain an aqueous adhesive.

(3) Production of single-sided polarizer

A one-side protective polarizer with a peeling film was produced in the following order. The polarizing film obtained in the above (1) was continuously conveyed, and a protective film was continuously loosened from a roll of a protective film (Zeonoa Film ZF14-023, thickness 23 占 퐉, manufactured by Nippon Zeon Co., Ltd.) . Further, the release film was continuously released from the roll of a release film (trade name "KC8UX2MW", thickness 80 μm, not saponified) produced by TAC film manufactured by Konica Minolta Opto Co., Ltd.

Subsequently, the water-based adhesive obtained in the above (2) was injected between the polarizing film and the protective film, and pure water was injected between the polarizing film and the peeling film and passed between the pair of bonding rolls to form a protective film / water- / Polarizing film / pure water / release film. Subsequently, the laminated film was conveyed, passed through a drying device, and heat-treated at 80 DEG C for 300 seconds to dry the water-based adhesive layer, and the pure water interposed between the polarizing film and the release film was removed by volatilization, Thereby obtaining a one-side protective polarizing plate with a peeling film. The peeling film was peeled from the one-side protective polarizing plate with the peeling film to obtain a one-side protective polarizing plate.

(4) Fabrication of one side protective polarizer with brightness enhancement film

A brightness enhancement film (trade name "APF", a reflection type polarizer manufactured by 3M) was bonded to the polarizing film side of the one-side polarizing plate obtained in the above (3) through an acrylic pressure sensitive adhesive to obtain a one side polarizing plate with a brightness enhancement film. At this time, the stretching shafts of the brightness enhancement films were bonded in parallel to the stretching direction of the polarizing film.

(5) Production of polarizer with acrylic pressure-sensitive adhesive

An acrylic pressure sensitive adhesive with a separator film was bonded to the brightness enhancement film side of the one side protective polarizing plate with the brightness enhancement film obtained in the above (4) to obtain a polarizing plate with an acrylic pressure sensitive adhesive.

(6) End face cutting

The polarizing plate with acrylic pressure sensitive adhesive (hereinafter simply referred to as "polarizing plate") obtained in the above (5) was cut into a size of 120 mm × 70 mm, and 100 sheets of the polarizing plate after the cutting were laminated by aligning four sides to obtain a polarizing plate laminate . The polarizer plate laminate was sandwiched between clamps having a major surface area smaller by one step than the area of the main surface of the polarizer plate laminate. The pressure of the clamp was also adjusted when the polarizing plate laminate was sandwiched. Next, all of the end faces of the four sides were cut using a cutting tool such as the cutting tool shown in Figs. 7 and 8, except that the first cutting group and the second cutting group had five cutting portions, respectively Polishing treatment). The cutting conditions of the end faces of the four sides were all the same.

The cutting tool used is arranged such that the projecting height of the cutting edge B becomes larger as the cutting portion located on the downstream side in the rotational direction of the cutting tool in the five cutting portions in each cutting portion group. The five cutting portions are disposed so that the distance from the rotational axis A to the cutting edge B becomes shorter as the cutting portion located on the downstream side in the rotational direction of the cutting tool becomes shorter. The cutting sections constituting the first cutting section group and the second cutting section group are arranged at equal intervals around the rotation axis and are arranged at positions opposed to each other through the rotation axis so that the protrusion height of the cutting edge and the height from the rotation axis to the cutting edge Two cutting sections having the same distance are arranged.

Specifically, the polarizing plate laminate is horizontally moved in a state in which the position of the cutting tool is fixed while the cutting tool is rotated about the rotation axis A thereof, thereby moving the polarizing plate laminate in parallel with the longitudinal direction of the end face of the polarizing plate laminate, The cutting tool was relatively moved with respect to the laminate so that the cutting edges of the respective cut portions were brought into contact with the two end faces facing each other and the end faces were simultaneously cut out. The relative movement was performed from one end of the end face to the other end. With this one-time relative movement, five kinds of cutting processes were performed by five kinds of cutting portions having different projecting heights of the cutting edge.

After cutting, the end portion of the polarizing plate was observed using a 3D measurement laser microscope (OLS4100, manufactured by Olympus Corporation), and the degree of inclination of the end face was checked.

(7) Heat shock test

As a durability test, a heat shock test was performed. Samples for heat shock test were prepared in the following order.

The end face abrasive sample obtained in the above (6) was adhered to a non-alkali glass plate ("Eagle-XG" manufactured by Corning Incorporated) and then subjected to a pressure treatment in an autoclave at a temperature of 50 ° C. and a pressure of 5 MPa for 20 minutes, Subsequently, the sample was allowed to stand for one day in an atmosphere at a temperature of 23 캜 and a relative humidity of 60%. After that, the temperature and the temperature were kept at -40 ° C (holding time 30 minutes), room temperature 23 ° C (holding time 5 minutes) and high temperature side 85 ° C (holding time 30 Minute] for 12 cycles under conditions set so that the test tank was changed. Thereafter, a sample was taken out, and the presence or absence of a crack-type appearance problem was confirmed using an optical microscope (VHX-5000, manufactured by KYOSEN Co., Ltd.) on the end sides of the sample. The number of cracks .

(8) Examples and Comparative Examples

(6) End face cutting processing &quot; and &quot; (7) Heat shock test &quot; are performed on the polarizing plate produced according to the procedure of the above (1) to (5).

[Example 1]

100 sheets of the polarizing plates were stacked and the protective film was set on the cutting device so that the polarizing film was on the upper side so that cutting was performed on the end face from the polarizing film side toward the protective film side. As a result of the cutting, the end face of the polarizing plate is inclined with respect to the thickness direction of the polarizing plate, and the edge portion on the opposite side to the joining face of the polarizing film on the side opposite to the protective film, Mu m inward.

Fig. 9 shows the end shape of the polarizing plate confirmed by the 3D measurement laser microscope. When the heat shock test was performed, the number of cracks observed in the polarizing film was zero.

[Example 2]

Except that triacetylcellulose (manufactured by Konica Minolta Opto Co., Ltd., Zero-tack, thickness: 20 占 퐉) in which a protective film was saponified was used. As a result of the cutting, the end face of the polarizing plate is inclined with respect to the thickness direction of the polarizing plate, and the end portion of the polarizing film opposite to the joining face with the protective film is 9 Mu m inward. Fig. 10 shows the end shape of the polarizing plate confirmed by the 3D measurement laser microscope. When the heat shock test was performed, the number of cracks observed in the polarizing film was zero.

[Comparative Example 1]

A polarizing plate having a cutting process was produced in the same manner as in Example 1 except that the polarizing film was set on the lower side of the protective film. That is, the cutting of the end face from the protective film side toward the polarizing film side is performed. As a result of the cutting, the end face of the polarizing plate is inclined with respect to the thickness direction of the polarizing plate, and the end side on the opposite side of the polarizing film from the side to be bonded with the protective film is 11 Mu m outside. Fig. 11 shows the end shape of the polarizing plate confirmed by the 3D measurement laser microscope. The heat shock test was conducted, and 71 cracks were observed in the polarizing film.

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

A polarizing plate, 2a: polarizing film end face, 2b: polarizing film end edge, 3: protective film, 3a: protective film edge, 4a: an end face of the reflective polarizer; 5: a pressure sensitive adhesive layer; and 100: a liquid crystal display device.

Claims (6)

A polarizing plate comprising a polarizer and a protective film laminated on only one side of the polarizer,
The end face of the polarizer and the end face of the protective film have a slope with respect to the thickness direction of the polarizer,
And the end face of the polarizer is located inside the end face of the protective film. The polarizer according to claim 1, further comprising a pressure sensitive adhesive layer laminated on a surface of the polarizer opposite to the side on which the protective film is laminated. The polarizing plate according to claim 2, further comprising an optical function film laminated through the pressure sensitive adhesive layer. The polarizing plate according to claim 3, wherein the end face of the optical function film is located outside the end face of the polarizer. The polarizing plate according to claim 3 or 4, wherein the optically functional film is a reflective polarizer. A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 5.

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