JP2001221917A - Linearly polarizing plate adhered with protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linearly polarizing plate adhered with a protective film in which only the defects in the linearly polarizing plate can be efficiently and visually inspected while defects in the protective film are hardly visible. SOLUTION: The linearly polarizing plate 60 adhered with a protective film is prepared by adhering a protective film 20 on at least one face of a linearly polarizing plate 10. When linearly polarized light 8 having the oscillation plane 7 parallel to the absorption axis 101 of the linearly polarizing plate 10 enters through the protective film 20, the luminous transmittance or the transmittance for rays of the linearly polarizing plate with the protective film is >=0.1% and <=5%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear polarizing plate having a protective film and a protective film attached to the surface of the linear polarizing plate.

[0002]

2. Description of the Related Art Generally, a linear polarizing plate has a function of absorbing linearly polarized light having a vibration plane parallel to its absorption axis and transmitting linearly polarized light having a vibration plane parallel to its transmission axis. An optical member that has been widely used as one of the optical components constituting a liquid crystal display device. In the linear polarizing plate, the absorption axis and the transmission axis cross each other at an angle of 90 °. The absorption axis and the transmission axis are also collectively called an optical axis.

As shown in FIGS. 1 and 2, such a linear polarizing plate 10 has a protective film 2 on at least one surface, preferably both surfaces, for the purpose of preventing damage.
0 and 30 are stuck and provided for inspection, transportation, storage and the like. When the protective films 20 and 30 are incorporated in a liquid crystal display device, they are peeled off from the linear polarizer 10 and discarded. FIG. 1A shows an example in which protective films 20 and 30 are directly adhered to both surfaces of a linear polarizing plate 10 to form a protective film-attached linear polarizing plate 60.
As shown in (B), an adhesive layer 40 is disposed on at least one surface of the linear polarizing plate 10, and the protective film 30 is attached via the adhesive layer 40, and the protective film-attached linear polarizing plate is attached. It may be 60. When the adhesive layer 40 is present, the protective film 30 also serves to protect the adhesive layer 40 and prevent foreign substances such as dust and dirt from adhering thereto. The protective film 30 attached on the adhesive layer 40 is also called a release film, a separate film, or the like.

[0004] In addition, as shown in FIG.
0, a compensating plate 50 is laminated on at least one surface thereof,
Preferably, the protective films 20 and 30 may be adhered to both sides to form the protective film-attached linear polarizing plate 60 (such a laminated linear polarizing plate and compensating plate is hereinafter referred to as It may be called "composite polarizing plate"). The compensator 50 used here is used to improve the viewing angle by aligning the orientation axis with the optical axis of the linear polarizer 10. In this case, as shown in FIG. 2A, the protective films 20 and 30 may be directly adhered to a composite polarizing plate including the linear polarizing plate 10 and the compensating plate 50, or as shown in FIGS. As shown in C), an adhesive layer 40 is provided on at least one surface of the composite polarizing plate including the linear polarizing plate 10 and the compensating plate 50.
The protective films 20 and 30 may be adhered through the interface. Of course, the adhesive layer 40 may be present on both sides.

[0005] The linear polarizing plate 10 shown in these examples is used.
Usually, as shown in FIG. 3, a protective layer 13 is laminated on one or both surfaces of a polarizer film 12.

If the linear polarizing plate 10 constituting the protective film-attached linear polarizing plate 60 has a defect such as a foreign matter or a scratch, the defect becomes a display defect of the liquid crystal display device. When incorporating into a display device, it is necessary to inspect for defects. In the inspection, for example, as shown in FIG. 4, the linear polarizer 10 to be inspected is crossed Nicols, that is, the absorption axes 101 of the linear polarizers 10 are 90 ° with respect to the analyzer 5 which is a standard linear polarizer for inspection. While illuminating the analyzer 5 from the light source 6 disposed on the back side of the analyzer 5 while arranging them so as to intersect at an angle, the method is performed by observing with the human eye 9 on the side opposite to the light source 6. Will be In this inspection method, since the analyzer 5 is crossed with the linear polarizer 10 to be inspected, of the light from the light source 6, the transmission axis 10 of the analyzer 5 is included.
Since only the light having a vibration plane parallel to 2 transmits through this analyzer 5, the linearly polarized light 8 having the vibration plane 7 parallel to the absorption axis 101 is applied to the linear polarizing plate 10 to be inspected. Incident.

The linearly polarized light 8 is completely blocked by the linearly polarizing plate 10 if there is no defect in the linearly polarizing plate 10 to be inspected. When the linear polarizing plate 10 is viewed from the eyes 9, it looks completely black. On the other hand, the linear polarizing plate 1 to be inspected
If there is a defect on the side of the analyzer 5 of 0, the incident linearly polarized light rotates its vibration plane or is depolarized due to this defect, so that it passes through the linearly polarizing plate 10 to be inspected. Therefore, this defect is observed as a bright spot,
Thereby, inspection can be performed. The defect on the opposite side of the linear polarizing plate 10 to be inspected is inspected by turning over the linear polarizing plate 10 on which the protective film 20 is stuck and performing the same operation. The observation direction in the inspection is usually the normal direction of the linear polarizing plate 10 to be inspected, and the position of the observer's eye 9 is on the direction of the linearly polarized light 8 from the light source 6.

In general, inspection, transportation, storage, and the like are performed on the linear polarizing plate 10 as the protective film-attached linear polarizing plate 60 having the protective film 20 adhered to the surface thereof, as described above. ing. When the protection film 20 with the protective film 20 attached to the surface thereof is to be inspected with the protective film 20 side facing the analyzer 5 side, the analyzer 5 and the linear polarizer 10
Even if they are arranged in crossed Nicols, light is transmitted over the entire surface of the linear polarizing plate 10 due to the retardation of the protective film 20, so-called light leakage occurs, or coloring due to interference is observed. In particular, there is a tendency that it is difficult to detect a minute defect by visual inspection.

In order to solve this problem, for example, FIG.
As shown in (1), a uniaxially or biaxially oriented film is used as the protective film 20, and the film may be stuck so that the slow axis 200 intersects the optical axis 100 of the linear polarizer at a specific angle. Can be Here, the optical axis 100 of the linear polarizing plate is the absorption axis 101 or the transmission axis 102. For example, using a uniaxially stretched film as the protective film 20,
If the slow axis 200 is arranged so as to be parallel to the optical axis 100 of the linear polarizing plate, that is, at an angle of 0 °,
Light leakage due to the retardation of the protective film 20 can be almost completely prevented, and the light is completely blocked over the entire surface of the linearly polarizing plate 10, so that the observer's eyes 9 shown in FIG. Therefore, a small bright spot caused by a minute defect can be easily visually observed, so that a visual inspection can be easily performed.

However, according to this inspection method, the defect of the protective film 20 also appears as a bright spot.
There was a tendency that it was difficult to distinguish the defect from the linear polarizing plate 10.

[0011]

Therefore, the present inventor has proposed:
Defects of the protective film 20 are hardly visible, and as a result of intensive research to develop a protective film-attached linear polarizer capable of efficiently visually inspecting only the defects of the linear polarizer 10, the absorption of the linear polarizer 10 was found. If the luminous transmittance or the light transmittance when the linearly polarized light 8 having the vibrating surface 7 parallel to the axis 101 is incident from the protective film 20 side is within a specific range, the protective film is inspected in crossed Nicols. The present inventors have found that small defects of the linear polarizing plate can be easily visually inspected with almost no visible defects, and the present invention has been accomplished.

[0012]

That is, according to the present invention, a protective film 2 is provided on at least one surface of a linear polarizing plate 10.
The linearly polarized light 8 having a vibrating surface 7 parallel to the absorption axis 101 of the linearly polarizing plate 10
Is a protective film-attached linear polarizing plate 60 having a luminous transmittance or a light transmittance of 0.1% or more and 5% or less when the light is incident from the protective film 20 side.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the layer structure of a linear polarizing plate 60 with a protective film adhered thereto is basically the same as that described above with reference to FIGS. That is, the linear polarizing plate 10 may be one in which a protective layer 13 is laminated on one or both surfaces of a polarizer film 12, as shown in FIG. 3, for example. As the polarizer film 12, for example, a film in which a dichroic dye such as iodine or a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin film can be used, and its thickness is usually about 10 to 30 μm. As the protective layer 13, for example, a film made of a cellulose resin such as triacetyl cellulose or diacetyl cellulose, an acrylic resin such as polymethyl methacrylate, or an ester resin such as polyethylene terephthalate is used. Usually 1
It is about 0 to 180 μm. Normally, the polarizer film 12 and the protective layer 13 are adhered by an adhesive layer. For this adhesive layer, for example, a polyvinyl alcohol-based adhesive is used.

As shown in FIGS. 1 and 2, protective films 20, 30 are adhered to at least one surface, preferably both surfaces, of the linear polarizing plate 10. Examples of the protective films 20 and 30 include ester resins such as polyethylene terephthalate, polyolefin resins such as polyethylene and polypropylene, acrylic resins such as polymethyl methacrylate, and cellulose resins such as triacetyl cellulose and diacetyl cellulose. A transparent polymer film made of a resin or the like is used. The thickness of the protective films 20 and 30 is usually 10 to
It is about 100 μm, preferably 20 μm or more, more preferably 30 μm or more, and 60 μm or less. The protective films 20 and 30 may be non-oriented polymer films or stretched polymer films. In the case of a stretched film, it may be a uniaxially stretched film or a biaxially stretched film. When the protective films 20 and 30 have in-plane retardation (R
₀ ), the value is, for example, 30 nm or more,
000 nm or less. As the protective films 20 and 30,
Those having antistatic properties can also be used. The protective films 20, 30 are transparent, and their total light transmittance is usually 80% or more.

The linear polarizing plate 10 and the protective films 20 and 30
As shown in FIG. 1 (B), an adhesive layer 40 may be interposed in one or both of them. When the adhesive layer 40 is provided in this manner, the adhesive is not particularly limited as long as it is a transparent and optically isotropic adhesive, but is usually a pressure-sensitive adhesive because it can be easily incorporated into a liquid crystal display device. Agent (adhesive) is used. As a pressure-sensitive adhesive (adhesive),
For example, acrylic pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives and the like can be mentioned. The thickness of the adhesive layer 40 is usually 10 to
It is about 50 μm.

Further, as shown in FIG. 2, a compensator 50 can be laminated on the linear polarizer 10. The compensator 50 is used with its alignment axis aligned with the optical axis of the linear polarizer 10, and is, for example, "Wide View" manufactured by Fuji Photo Film Co., Ltd., or "NH Film" manufactured by Nisseki Liquid Crystal Co., Ltd. And a viewing angle compensation film such as "VAC film" manufactured by Sumitomo Chemical Co., Ltd., and an unstretched film.
Its thickness is usually about 10 to 500 μm. The linear polarizing plate 10 and the compensator 50 are usually laminated via an adhesive layer, but the layer of the compensator 50 may be formed directly on the linear polarizer 10. In the case where a linear polarizing plate 10 having a protective layer 13 laminated on only one surface of a polarizer film 12 as shown in FIG. 3A is used, the compensator 50 usually includes a polarizer. It is laminated on the surface on the film 12 side. When the compensator 50 has an orientation axis, the angle between its optical axis and the absorption axis of the linear polarizer 10 is either 0 ° or 90 °.

As described above, the compensator 50 is attached to the linear polarizer 10.
When using a composite polarizing plate on which is laminated, the protective film on the compensating plate 50 side is adhered on the adhesive layer if the surface on the compensating plate 50 side has an adhesive layer. Will be. When the composite polarizing plate has an adhesive layer on the surface on the side of the linear polarizing plate 10, the protective film on the side of the linear polarizing plate 10 is stuck on the adhesive layer.
The protective film stuck on the adhesive layer is also called a release film, a separate film, or the like.

In the present invention, at least one surface of the linear polarizing plate 10 or at least one surface of the compensating plate 50 when the compensating plate 50 is laminated on the linear polarizing plate 10,
Protective films 20, 30 have been applied and FIG.
This will be described with reference to FIG.
When the linearly polarized light 8 having the vibrating surface 7 parallel to 01 is incident from one of the protective films 20, the light transmittance or the luminous transmittance is adjusted to be 0.1% or more and 5% or less. .

As shown in FIG. 4, the light transmittance can be measured by irradiating the linearly polarized light 8 from above the protective film 20 of the linearly polarizing plate 60 with the protective film adhered thereto. The linearly polarized light 8 to be irradiated has its vibration surface 7 parallel to the absorption axis 101 of the linearly polarizing plate 10. Such linearly polarized light 8 can be obtained by the analyzer 5 arranged in a crossed Nicols between the light source 6 and the linearly polarizing plate 10. Of such linearly polarized light 8, by measuring the intensity of light that passes through the protective film-attached linearly polarizing plate 60, for example, with a haze computer,
Light transmittance can be determined. Further, the intensity of the transmitted light is obtained for each wavelength, and the luminous transmittance can be calculated from this. The luminous transmittance is a transmittance obtained by adding a correction based on human luminosity to the transmittance of each wavelength in the visible light wavelength range when the standard light (C light source) is used.
It can be calculated from the transmittance at each wavelength according to the provisions of 701. It is preferable to adopt the latter for the light transmittance and the luminosity transmittance, but the light transmittance may be used for convenience.

If the luminous transmittance or light transmittance measured as described above falls below 0.1%, the protective film 2
Since a defect such as a scratch or a foreign matter tends to be noticeable, and this tendency becomes stronger as the transmittance becomes smaller, the luminous transmittance or the light transmittance is preferably 0.2% or more, and more preferably 0.2% or more. It is better to be more than .5%.
On the other hand, if the luminous transmittance or light transmittance exceeds 5%,
Foreign matter on the linear polarizing plate 10 becomes difficult to see, and the inspection time tends to be longer. This tendency becomes stronger as the transmittance increases, so that the luminous transmittance or the light transmittance is preferably 3% or less. To be.

In order for the protective film-attached linear polarizing plate 60 to satisfy such luminous transmittance or light transmittance, for example, a polymer film containing fine particles is stretched as the protective films 20 and 30. What is necessary is just to use the film obtained. Examples of the fine particles contained in the polymer film include an anti-blocking agent such as silica fine particles. The anti-blocking agent is an additive that is usually added to the polymer film to prevent the laminated polymer films from fusing together (blocking). When a polymer film containing such fine particles is stretched, a region in which the orientation of the polymer is disordered locally occurs near each fine particle. Such a region in which the orientation is disturbed rotates or depolarizes the vibration plane of the linearly polarized light incident on the film, so that the linearly polarizing plate to which the film is adhered vibrates parallel to its absorption axis. It is considered that linearly polarized light having a plane is slightly transmitted.

In the protective films 20 and 30, when the number and the area of the regions in which the orientation is disturbed are increased, the luminous transmittance or the light transmittance is also increased. And the luminous transmittance tends to increase. Further, when the polymer film containing fine particles is biaxially stretched, the area of the region in which the orientation is disordered is more likely to be larger than that in the case of uniaxially stretching, so that the luminous transmittance or the light transmittance is increased. There is a tendency. It is necessary that the area of the region in which the orientation is disordered is smaller than the size of the defect to be inspected.

As shown in FIG. 6, when such a stretched film is used as at least one protective film 20, the slow axis 200 of the protective film 20 is aligned with the optical axis 100 of the linear polarizing plate 10. It is stuck so as to intersect at an angle θ between 0 ° and 15 °. The optical axis 100 of the linear polarizing plate 10 may be the absorption axis 101 shown in FIG. In FIG. 6,
Although the linear polarizing plate 10 and the protective film 20 are shown separately for convenience of explanation, they are actually in close contact with each other or in close contact with each other via an adhesive layer and / or a compensator.

In the present invention, the protective film 2
As 0 and 30, a uniaxially or biaxially oriented film can also be used. A protective film 20 comprising such an oriented film and substantially free of fine particles as described above.
Is that the slow axis 200 is the optical axis 100 of the linear polarizer 10
Is attached to the linear polarizing plate 10 so as to intersect at an angle θ of more than 0 ° and 15 ° or less (see FIG. 6). Is set so that the luminous transmittance or light transmittance of the linear polarizing plate to which the protective film is attached is 0.1% or more and 5% or less.

As the uniaxially or biaxially oriented film, a uniaxially stretched film or a biaxially stretched film can be used. When a film to which only such an orientation is applied is used as the protective film 20 and its slow axis 200 is arranged so as to cross the optical axis 100 of the linear polarizing plate 10 at an angle of 0 °, the luminous transmittance or light transmittance When it is arranged to intersect at an angle exceeding 15 °, the luminous transmittance or the light transmittance tends to exceed 5%. The optical axis 100 of the linear polarizer is
1 or the transmission axis 102.

When a composite polarizing plate in which a compensating plate 50 is laminated on the linear polarizing plate 10 as shown in FIG. 2 is used, as shown in FIG. 0 ° or 90 ° with respect to the optical axis 100 of the plate 10
Are arranged at an angle. In this figure, the optical axis 5 of the compensator 50 is
Although 00 is displayed to intersect at an angle of 90 °,
Since the optical axis 100 of the linear polarizing plate 10 may be the absorption axis 101 or the transmission axis 102, the meaning is the same whether it is 0 ° or 90 °. Then, the protective films 20, 30 are stuck so that the slow axes 200, 300 of the protective films 20, 30 intersect with the optical axis of the linear polarizing plate 10 at an angle θ of 0 ° or more and 15 ° or less, respectively. You. When a polymer film containing no fine particles and uniaxially or biaxially oriented is used as the protective films 20 and 30, the angle θ is more than 0 ° and 15 ° or less as described above. In FIG. 7, the linear polarizer 10 and the compensator 5
Although 0 and the protective films 20 and 30 are shown separately for convenience of explanation, they are actually in close contact with each other via an adhesive layer as necessary.

In the present invention, the protective films 20, 30
May be attached to one surface of the linear polarizing plate 10 or a laminate of the linear polarizing plate 10 and the compensator 50, or may be attached to both surfaces. When the protective films 20 and 30 are attached to both surfaces, the luminous transmittance or the light transmittance for the linearly polarized light incident from at least one of the protective films 20 or 30 may satisfy the above relationship. If the luminous transmittance or the light transmittance for the linearly polarized light incident from the other protective film 30 or 20 side also satisfies the above relationship, the defect inspection on both surfaces of the linearly polarizing plate can be easily performed. Is more preferable.

The protective film-attached linear polarizing plate 60 of the present invention
In order to visually inspect the linear polarizing plate 10 for defects,
For example, as shown in FIG. 4, the linearly polarized light 8 may be irradiated from the protective film 20 side of the protective film-attached linearly polarizing plate 60. The linearly polarized light 8 to be irradiated has a vibrating surface 7 parallel to the absorption axis 101 of the linearly polarizing plate. The linearly polarized light 8 can be obtained by transmitting the light from the light source 6 through the linearly polarizing plate 10 and the analyzer 5 arranged in crossed Nicols. From the position of the eyes 9 of the observer located on the side opposite to the light source 6,
0 was observed, this protective film-attached linear polarizing plate 6
If there is no defect in 0, it looks black over the entire surface. On the other hand, if the linear polarizing plate 10 has a defect on the protective film 20 side (light source side), the defective portion is observed as a bright spot. In the case of the protective film-attached linear polarizing plate 60 according to the present invention, only the defects existing on the linear polarizing plate 10 are actually observed. It can be inspected for defects and remove defective products.

[0029]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention.

Example 1 A film obtained by biaxially stretching a polyethylene terephthalate film containing silica particles having a particle diameter of 1 to 5 μm as an anti-blocking agent, wherein the size of the region in which the orientation was disordered was 20 μm × One having a thickness of about 70 μm was used as a protective film. This protective film is attached to both sides of a 14-inch linear polarizing plate such that the slow axis of the protective film and the absorption axis of the linear polarizing plate intersect at 90 °,
A linear polarizing plate with a protective film attached was used.

The luminous transmittance when the linearly polarized light having a vibration plane parallel to the absorption axis from one surface side of the linearly polarizing plate was incident was 0.5%. The luminous transmittance when the linearly polarized light having a vibration plane parallel to the absorption axis of the linear polarizing plate was incident from the other surface side was also 0.5%. FIG. 8 shows a transmittance spectrum when linearly polarized light having a vibration plane parallel to the absorption axis of the linear polarizing plate is incident from one surface side of the linear polarizing plate with the protective film attached thereto.

FIG. 4 shows the linear polarizing plate having the protective film adhered thereto.
And the linear polarizing plate was inspected for defects.
That is, the analyzer 5 is arranged on the linear polarizer 10 and the cross Nicol, and the light source 6 is arranged on the opposite side of the analyzer 5 from the linear polarizer 10, and the light from the light source 6 passes through the analyzer 5. The thus obtained linearly polarized light 8 was irradiated from one surface side of the protective film-attached linearly polarizing plate 60 and visually inspected by the eyes 9 of the observer located on the opposite side to the light source 6. As a result, the linear polarizing plate 10 could be inspected for defects such as foreign matter and scratches without being affected by defects such as foreign matter and scratches on the protective film 20. At this time, the time required for inspection of one linear polarizing plate was 11 seconds.

Example 2 As a protective film, a polyethylene terephthalate film containing the same silica particles as used in Example 1, but a film obtained by uniaxially stretching the same, and having A protective film-attached linear polarizing plate was produced in the same manner as in Example 1 except that a size of about 5 μm × 70 μm was used. The luminous transmittance at the time when linearly polarized light having a vibrating plane parallel to the absorption axis from one surface side of the linearly polarizing plate was incident was 0.2%. The luminous transmittance when the linearly polarized light having a vibration plane parallel to the absorption axis of the linear polarizing plate was incident from the other surface side was also 0.2%.

When the linear polarizing plate with the protective film adhered thereto was visually inspected in the same manner as in Example 1, it was found that the linear polarizing plate was not affected by defects such as foreign particles and scratches on the protective film. Inspection of defects could be performed. At this time, the time required for inspection of one linear polarizing plate was 11
Seconds.

Comparative Example 1 A protective film was adhered in the same manner as in Example 1 except that a film obtained by uniaxially stretching a polyethylene terephthalate film produced without adding silica particles was used as the protective film. A linear polarizing plate was produced. In the protective film used here, a region with disordered orientation could not be confirmed. The luminous transmittance when the linearly polarized light having the vibration plane parallel to the absorption axis was incident from one surface side of the linearly polarizing plate was 0.05%. The luminous transmittance when the linearly polarized light having a vibration plane parallel to the absorption axis of the linear polarizing plate was incident from the other surface side was also 0.05%. FIG. 9 shows a transmittance spectrum when linearly polarized light having a vibration plane parallel to the absorption axis of the linearly polarizing plate is incident from one surface side of the linearly polarizing plate with the protective film attached thereto.

The linear polarizing plate having the protective film adhered thereto is 255
Sheets were prepared and all were inspected in the same manner as in Example 1. As a result, the time required for the inspection was 11 seconds / sheet. In this inspection, 23 sheets were determined to be defective, of which 16 sheets had no defects in the linear polarizing plate and had defects in the protective film.

Comparative Example 2 The protective film used in Example 1 was placed on both sides of a 14-inch linear polarizing plate such that the slow axis of the protective film and the absorption axis of the linear polarizing plate crossed at an angle of 65 °. Stick it on,
A linear polarizing plate with a protective film attached was prepared. The luminous transmittance when the linearly polarized light having a vibration plane parallel to the absorption axis of the linearly polarizing plate was incident from one surface side of the linearly polarizing plate was 20%. The luminous transmittance when the linearly polarized light having a vibration plane parallel to the absorption axis of the linear polarizing plate was incident from the other surface side was also 20%.

When the linear polarizing plate with the protective film adhered thereto was visually inspected in the same manner as in Example 1, it was difficult to confirm any foreign matter or scratch on the linear polarizing plate, and the time required for inspection of one linear polarizing plate was 15 minutes. Seconds.

Example 3 A linear polarizing plate composed of a triacetyl cellulose film having a thickness of 80 μm / a polyvinyl alcohol film having a thickness of 20 μm on which iodine was adsorbed / aligned / a triacetyl cellulose film having a thickness of 80 μm, and a compensator “Wide View” having a thickness of 100 μm (Manufactured by Fuji Photo Film Co., Ltd.) using a composite polarizing plate laminated so that the orientation axis of the latter forms an angle of 0 ° with the absorption axis of the former. On the other hand, a film obtained by biaxially stretching a polyethylene terephthalate film containing silica particles having a particle size of 1 to 5 μm as an anti-blocking agent, and having a disordered orientation region of about 20 μm × 70 μm Was used as a protective film (also called a separate film). Then, an adhesive layer is provided on the surface of the compensator of the composite polarizing plate, and the protective film is formed on the adhesive layer such that the slow axis has an angle of 90 ° with respect to the absorption axis of the linear polarizing plate. The composite polarizing plate was adhered so as to form a protective film-attached composite polarizing plate. From the protective film side of this composite polarizing plate, the light transmittance when linearly polarized light having a vibration plane parallel to the absorption axis of the linear polarizing plate was incident was measured by a haze computer manufactured by Suga Test Instruments Co., Ltd. , 0.4%.

FIG. 4 shows the composite polarizing plate having the protective film adhered thereto.
And the linear polarizing plate was inspected for defects.
That is, the analyzer 5 is arranged on the linear polarizing plate 10 and crossed Nicols, and the light source 6 is located on the opposite side of the analyzer 5 from the linear polarizing plate 10.
And the linearly polarized light 8 obtained by the light from the light source 6 passing through the analyzer 5 is irradiated from the protective film 20 side, and visually observed by the observer's eyes 9 located on the opposite side to the light source 6. Inspected. As a result, it was possible to inspect the composite polarizing plate for defects such as foreign matters and scratches without being affected by defects such as foreign matters and scratches of the protective film 20. At this time,
The time required to inspect one composite polarizing plate was 11 seconds.

Example 4 As a protective film, a polyethylene terephthalate film containing the same silica particles as used in Example 3 was used. The film was obtained by uniaxially stretching the film, and was used in a region where the orientation was disordered. A protective film-attached composite polarizing plate was prepared in the same manner as in Example 3, except that a size of about 5 μm × 70 μm was used. From the protective film side of this composite polarizing plate, the light transmittance when linearly polarized light having a vibration plane parallel to the absorption axis of the linear polarizing plate is incident,
0.8%.

The composite polarizing plate with the protective film adhered thereto was visually inspected in the same manner as in Example 3. As a result, it was found that the composite polarizing plate was not affected by foreign substances and scratches. Inspection of defects could be performed. At this time, the time required to inspect one composite polarizing plate was 11
Seconds.

Comparative Example 3 A protective film was adhered in the same manner as in Example 3 except that a film obtained by uniaxially stretching a polyethylene terephthalate film produced without adding silica particles was used as the protective film. A composite polarizing plate was produced. When linearly polarized light having a vibration plane parallel to the absorption axis of the linear polarizing plate was incident from the protective film side of the composite polarizing plate, the light transmittance was 0.0%.

This protective film-attached composite polarizing plate was coated with 255
When all the sheets were prepared and inspected in the same manner as in Example 3, the time required for the inspection was 11 seconds / sheet. In this inspection, 23 sheets were determined to be defective, of which 16 sheets had no defects in the linear polarizing plate and had defects in the protective film.

Comparative Example 4 The protective film used in Example 3 was attached to the compensator surface of the composite polarizing plate such that the slow axis of the protective film and the absorption axis of the linear polarizing plate crossed at an angle of 65 °. Thus, a protective film-attached composite polarizing plate was produced. The transmittance when linearly polarized light having a vibration plane parallel to the absorption axis of the linear polarizing plate was incident from the protective film side of the composite polarizing plate was 10%.

When the composite polarizing plate with the protective film adhered thereto was visually inspected in the same manner as in Example 3, it was difficult to confirm foreign substances and scratches on the composite polarizing plate, and the time required for testing one composite polarizing plate was 15 minutes. Seconds.

[0047]

According to the linear polarizing plate to which the protective film is adhered according to the present invention, the defect of the linear polarizing plate can be visually inspected efficiently without being substantially affected by the defect of the protective film. Further, its optical performance is equivalent to that of a conventional product.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a linear polarizing plate having a protective film attached thereto.

FIG. 2 is a schematic cross-sectional view showing another example of the protective film-attached linear polarizing plate, in which a compensator is laminated.

FIG. 3 is a schematic cross-sectional view illustrating an example of a layer configuration of a linear polarizing plate itself.

FIG. 4 is a perspective view schematically showing a positional relationship between a protective film adhered linear polarizing plate and an analyzer in a visual inspection.

FIG. 5 is a perspective view schematically showing the relationship between the slow axis of the protective film and the optical axis of the linear polarizing plate in a conventional protective film-attached linear polarizing plate using a uniaxially stretched film as the protective film.

FIG. 6 is a perspective view schematically showing the relationship between the slow axis of the protective film and the optical axis of the linear polarizing plate in the linear polarizing plate with a protective film adhered thereto of the present invention.

FIG. 7 schematically shows the relationship among the slow axis of the protective film, the optical axis of the linear polarizing plate, and the optical axis of the compensating plate when the present invention is applied to a linear polarizing plate on which a compensating plate is laminated. FIG.

FIG. 8 is a transmittance spectrum when linearly polarized light having a vibration plane parallel to the absorption axis of the linearly polarizing plate is incident from one surface side of the linearly polarizing plate to which the protective film is attached in Example 1. It is.

FIG. 9 shows a transmittance spectrum when linearly polarized light having a vibration plane parallel to the absorption axis of the linearly polarizing plate is incident from one surface side of the linearly polarizing plate to which the protective film is attached in Comparative Example 1. It is.

[Explanation of symbols]

 Reference numeral 5: analyzer, 6: light source, 7: vibration plane of linearly polarized light, 8: linearly polarized light, 9: eyes of the observer, 10: linearly polarizing plate, 100: linearly polarizing plate Optical axis, 101: Absorption axis of linear polarizing plate, 102: Transmission axis of linear polarizing plate, 12: Polarizer film, 13: Protective layer, 20: One protective film, 200: One protection Slow axis of film, 30: The other protective film, 300: Slow axis of the other protective film, 40: Adhesive layer, 50: Compensating plate, 500: Optical axis of the compensating plate, 60: ... Protective film attached linear polarizer.

Claims (7)

[Claims] 1. A protection film is attached to at least one surface of a linear polarizing plate, and linearly polarized light having a vibration plane parallel to an absorption axis of the linear polarizing plate is incident from the protection film side. A luminous transmittance or a light transmittance of 0.1% or more and 5% or less when the protective film is applied. 2. The linear polarizing plate according to claim 1, wherein the protective film is a film obtained by stretching a polymer film containing fine particles. 3. The protective film according to claim 2, wherein the protective film is attached such that its slow axis forms an angle of 0 ° to 15 ° with respect to the optical axis of the linear polarizing plate. Wearable linear polarizer. 4. The protective film is oriented uniaxially or biaxially, and is adhered so that its slow axis crosses the optical axis of the linear polarizing plate at an angle of more than 0 ° and 15 ° or less. The protective film-attached linear polarizing plate according to claim 1. 5. A linearly polarizing protective film according to claim 1, wherein a compensating plate is laminated on the linearly polarizing plate, and a protective film is bonded on at least one surface side. Board. 6. The protective film-attached linear polarizing plate according to claim 5, wherein a protective film is attached via an adhesive layer to at least the compensating plate side of the laminate of the linear polarizing plate and the compensating plate. 7. The protective film-attached linearly polarized light according to claim 5, wherein a protective film is adhered via an adhesive layer to the side of the linearly polarizing plate of the laminate of the linearly polarizing plate and the compensating plate. Board.