JP4218102B2 - Protective film attached linear polarizing plate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a protective film-attached linear polarizing plate in which protective films are attached to both sides of a linear polarizing plate.
[0002]
[Prior art]
Linear polarizing plate is useful as a single one of the optical components constituting the liquid crystal display device. Such a linear polarizing plate has a defect in the display of the liquid crystal display device if foreign matter adheres to it, so that inspection is indispensable at the time of shipment or incorporation into the liquid crystal display device. For example, as shown in FIG. 3 , the inspection is performed by arranging the linearly polarizing plate (1) to be inspected with respect to the inspection linearly polarizing plate (7) in a crossed Nicol state. It carried out by a method of visually observed while illuminating from the back side. Since both linear polarizing plates (7, 1) are crossed Nicols, the light transmitted through the inspection linear polarizing plate (7) is completely blocked by the linear polarizing plate (1) to be inspected. as the foreign matter when the inspection linearly polarizing plate side of the linear polarizer (1) to be examined is foreign matter is observed as bright points, thereby Ru can be inspected. The opposite side of the foreign substance is inspected similarly turned over linear polarizer (1) to be examined. The observation direction in the inspection is usually the normal direction (L0) of the linearly polarizing plate (1) to be inspected, and the position of the operator's eyes (6) is on this normal (L0).
[0003]
On the other hand, as shown in FIG. 1 and FIG. 2 , the linear polarizing plate (1) is a protective film adhering straight line in which protective films (2, 3) for preventing scratches are adhering to both surfaces. as polarizing plate (4), inspection, transportation, Ru is subjected to such storage. Protection film (2, 3) is peeled off from the linear polarizing plate when incorporated in a liquid crystal display device is to be discarded. In order to linearly polarizing plate, such as incorporation into the liquid crystal display device, when a number of the adhesive layer is provided on a surface or both surfaces of its one, therefore dust to the adhesive layer, foreign matter adhesion of dust In many cases, a protective film for preventing this is stuck on the adhesive layer. Here, the protective film stuck on the adhesive layer is also called a release film, a separate film, or the like.
[0004]
However, when trying to visually inspect the protective film-attached linear polarizing plate in which the protective film is attached on both sides in this way, coloring due to interference due to retardation of the protective film is observed, and foreign matter is confirmed. Tended to be difficult. This tendency was particularly remarkable when inspecting minute foreign matters of 70 μm or less. The presence of such minute foreign matters is particularly a problem in recent high-definition liquid crystal display devices with high resolution.
[0005]
In order to solve this problem, a method of sticking the biaxially oriented protective film so that the slow axis direction and the direction of the absorption axis of the linear polarizing plate are at a specific angle is also conceivable. In such a protective film-attached linear polarizing plate with a biaxially oriented protective film attached, coloring is not observed and inspection is easy when inspecting from the normal direction (L0) of the linear polarizing plate. It becomes.
[0006]
However, in this method, an attempt to inspect and observe obliquely even slightly, coloration will appear, the position of the eyes of the test products operation skill, attitude, etc. is restricted arrangement of the linear polarizing plate for inspection End up. Further, for example, when you try to inspect a large linear polarizing plate of 10 inches or more in size, as shown in FIG. 3, the peripheral portion of the linear polarizing plate is visible from an oblique direction (L1, L2) when overlooking the entire DOO Ri name to be observed is colored, confirmation of the foreign matter of this portion there is a problem that it is not still easy.
[0007]
[Problems to be solved by the invention]
The present inventor has intensively studied to develop an oblique inspection be observed from the direction for ease protective film sticking linear polarizer cross nicol, the direction of the slow axis of the protective film that is uniaxially oriented It has been found that such a problem can be solved by using in a specific direction, and the present invention has been achieved.
[0008]
[Means for Solving the Problems]
That is, the present invention is the onto the adhesive layer (5), the slow axis of to our resources oriented uniaxially linear linear polarizer (1) having on one surface an adhesive layer (5) has a first protective film composed of polyethylene terephthalate, which is adhered at an angle of for the absorption axis 0 ° ± 15 ° or 90 ° ± 15 ° of the polarizer (1), linear polarizer ( The other surface of 1) is oriented uniaxially and its slow axis has an angle in the range of 0 ° ± 15 ° or 90 ° ± 15 ° with respect to the absorption axis of the linearly polarizing plate (1). Provided is a protective film-attached linearly polarizing plate (4) having a second protective film made of polyethylene terephthalate that is attached as it is. The laminated structural example of the protective film sticking linear polarizing plate of this invention is shown in FIG.1 and FIG.2.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The linearly polarizing plate (1) applied to the protective film-attached linearly polarizing plate of the present invention is a normal linearly polarizing plate . For example , as shown in FIG. 1 and FIG. one or both surfaces protective film) (13) Ru include those are laminated. Polarizer film (12), for example, vinyl alcohol-based resin film such as polyvinyl alcohol is dyed Ri by the iodine or dichroic dye (PVA) is used, its thickness is usually about 10 to 30 [mu] m. As the protective film (13), for example, triacetyl cellulose (TAC) and diacetyl cellulose (DAC) cellulose resins such as acrylic resin, is made of poly ester-based resin films such as polyethylene terephthalate (PET) is used, its thickness is usually about 10~180μm. Polarizer and the film (12) and the protective film (13) are more adhesive to the adhesive, this adhesive, for example polyvinyl alcohol-based adhesive and the like are used.
[0010]
An adhesive layer (5) is provided on one surface of the linearly polarizing plate (1), and a first protective film (3) is adhered thereon . Moreover, the 2nd protective film (2) is stuck on the other surface of the linearly-polarizing plate (1). And these 1st protective films (3) and 2nd protective films (2) are comprised by what is orientated uniaxially , respectively . In the case of not being uniaxially oriented, for example, biaxially oriented, coloring occurs even when observed slightly obliquely with crossed Nicols.
[0011]
As material for the protection film, such as PET and poly ester resins, polyethylene (PE) and polypropylene (PP) polyolefin resins such as an acrylic resin, a cellulose-based resin such as TAC or DAC are known In the present invention, PET is adopted as the protective film (2, 3) . Moreover, the thickness of a protective film (2, 3) is about 10-100 micrometers normally , Preferably it is about 30-60 micrometers.
[0012]
In order to align such a film uniaxially, for example, it may be stretched uniaxially. The method for stretching in the uniaxial direction is not particularly limited. A commercially available film can be used as the uniaxially oriented film thus stretched in a uniaxial direction, and a film imparted with antistatic performance can also be used. The in-plane retardation (R0) of the uniaxially oriented protective film is, for example , 30 nm or more and 6000 nm or less.
[0013]
Each of the protective films (2, 3) oriented in the same axis has a slow axis in the range of 0 ° ± 15 ° or 90 ° ± 15 ° with respect to the absorption axis of the linearly polarizing plate (1) . Affixed to form an angle . Example of relationship between absorption axis (11) of linearly polarizing plate (1), slow axis (31) of first protective film (3), and slow axis (21) of second protective film (2) Is shown in a schematic perspective view in FIG . The If Ru beyond the scope of this angle is 0 ° the range of ± 15 ° or 90 ° ± 15 °, it tends to easily colored occurs when observed from an oblique direction in a crossed Nicol state. This angle is preferably in the range of 0 ° ± 10 ° or in the range of 90 ° ± 10 °, more preferably in the range of 0 ° ± 5 ° or in the range of 90 ° ± 5 °, particularly preferably substantially. 0 ° or 90 °.
[0014]
Adhesive layer disposed on one surface of the linear polarizer (1) (5), such limited particularly as long as isotropic adhesive transparent Iga, set only to the liquid crystal display device In general, a pressure-sensitive adhesive (adhesive) is used because it is easy to insert. Examples of such pressure-sensitive adhesives include acrylic pressure-sensitive adhesives and urethane-based pressure sensitive adhesives.
[0015]
As linear polarizer (1), in the case of using those shown in FIG. 2, one side only protective film of the polarizer film (12) (13) is laminated, contact Chakuzaiso (5) usually, Ru is provided on the polarizer film (12).
[0016]
Thus, the protective film sticking linear polarizer of the present invention, possess an adhesive layer (5) on one side of the linear polarizer (1), on which the adhesive layer (5), a uniaxial It is oriented and its slow axis is in the range of 0 ° ± 15 ° or 90 ° ± 15 °, preferably in the range of 0 ° ± 10 ° or 90 ° ± with respect to the absorption axis of the linearly polarizing plate (5) . First protection applied to form an angle of 10 °, more preferably 0 ° ± 5 ° or 90 ° ± 5 °, particularly preferably substantially 0 ° or 90 °. It has a film (3) , and the other surface of the linearly polarizing plate (1) is also uniaxially oriented and its slow axis is in the range of 0 ° ± 15 ° with respect to the absorption axis of the linearly polarizing plate or 90 In the range of ± 15 °, preferably in the range of 0 ° ± 10 ° or in the range of 90 ° ± 10 °, more preferably in the range of 0 ° ± 5 ° or in the range of 90 ° ± 5 °, particularly preferred Properly the Ru Monodea having a second protective film is affixed at an angle of substantially 0 ° or 90 ° (2).
[0017]
In addition, the 1st protective film (3) stuck on an adhesive bond layer (5) is also called a peeling film, a release film, and a separate film.
[0018]
In the protective film sticking linear polarizer of the present invention (4), if the linear polarizer (1) has an adhesive layer on the other surface, the second protection which is adhered to the other surface A film will be stuck on the said adhesive bond layer.
[0019]
Te protective film sticking linear polarizer (4) smell of the present invention, first and second protective films are oriented in a uniaxial (2, 3) is made to FIG. 4, which shows as a representative with a protective film (2) Referring to the in- plane retardation, that is, the retardation (R0) measured from the normal direction (L0) of the protective film (2) , and tilted by 30 ° around the fast axis (22) from the normal direction direction ratio of letters and retardation (R30) measured from (L30) (R0 / R30) is 1.5 or less, more have preferably be 1.3 or less. When this ratio (R0 / R30) exceeds 1.5, there is a tendency that the angle region in which coloring easily occurs when observed from an oblique direction under crossed Nicols. Usually, the fast axis (22) is orthogonal to the slow axis (21).
[0020]
【The invention's effect】
According to the protective film-attached linear polarizing plate of the present invention, coloring does not occur even when observed in an oblique direction with crossed Nicols, so even if the protective film is attached , only from the normal direction. It not, by observing from an oblique Me direction, can be easily inspected foreign matter can Rukoto improve the workability of inspection.
[0021]
【Example】
EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated in detail, this invention is not limited to these Examples.
[0022]
Example 1
TAC film adhesive layer on one surface of the linear polarizer (1) consisting of three layers (thickness: 80 [mu] m) / iodine stained PVA film (thickness 20 [mu] m) / TAC film (thickness 80 [mu] m) [Acrylic A pressure-sensitive adhesive] (5) was prepared. On the adhesive layer (5) , a uniaxially oriented protective film (separate film) [PET film produced by uniaxial stretching, R0 = 3900 nm, R0 / R30 = 1.12, thickness 40 μm] ( 3 ) Was attached so that its slow axis ( 31 ) was at an angle of 90 ° with respect to the absorption axis (11) of the linearly polarizing plate (1) . Adhesive layer (5) in face to face in opposition side which is provided, [PET film produced by uniaxial stretching, R0 = 3900nm, R0 / R30 = 1.12, thickness 40μm] protective film (2) Was stuck so that its slow axis ( 21 ) forms an angle of 90 ° with respect to the absorption axis (11) of the linearly polarizing plate . Confucius give the protective film sticking linear polarizer (4) [the size 210 mm × 300 mm] (see FIGS. 1 and 5).
[0023]
This protective film-attached linearly polarizing plate (4) is placed above the inspection linearly polarizing plate (7) as shown in FIG. 3 and visually inspected from the position 200 mm above the center as a crossed Nicol. Went. Inspection of this protective film-attached linearly polarizing plate can be carried out satisfactorily over the entire surface of the linearly polarizing plate without changing the position of the eyes, and the time required to inspect both surfaces is about 20 seconds per sheet. Met.
[0024]
The transmittance spectrum of transmitted light measured from the normal direction with the adhesive film (5) side of the protective film-attached linearly polarizing plate (4) on the bottom , that is, the inspection linearly polarizing plate side , and the linearly polarizing plate FIG. 6 shows transmittance spectra of transmitted light measured from a direction (oblique direction) tilted by 30 ° from the normal direction with an in-plane reference line forming an angle of 45 ° with respect to the absorption axis (11) of FIG. Show. When measured not only in the normal direction but also in an oblique direction , it can be seen that the transmissivity is 1.5% or less over almost the entire visible light region and a black color is exhibited.
[0025]
In addition, the transmittance | permeability spectrum at the time of measuring with the protective film sticking linear polarizing plate upside down and the adhesive layer side up is also the same.
[0026]
Comparative Example 1
Instead of the uniaxially oriented protective film (separate film) ( 3 ), the biaxially oriented protective film (separate film) [PET film produced by biaxial stretching, R0 = 1380 nm, R0 / R30 = 2.6, except that the slow axis and the thickness 38μm] (31) is attached at an angle of 90 ° to the absorption axis (11) of the linear polarizer, as in embodiment 1 operation Thus, a protective film-attached linear polarizing plate [size 210 mm × 300 mm] was obtained.
[0027]
This protective film-attached linearly polarizing plate was placed above the inspection linearly polarizing plate (7) according to FIG. 3 and inspected by visual observation from the position 200 mm above the center as a crossed Nicol. The inspection of the protective film-attached linearly polarizing plate could be performed without changing the position of the eyes in the central part, but the surrounding four sides, particularly the four corners, were colored by interference, and the eyes It was not easy to perform inspection without changing the position, and inspection could not be performed satisfactorily over the entire surface of the linear polarizing plate. For this reason, the time required to inspect both surfaces was about 35 seconds per sheet.
[0028]
Under the adhesive layer side of the protective film sticking linear polarizing plate, that is, the inspection linear polarizer side, the transmittance spectrum of the transmitted light measured from the normal direction, and for the absorption axis of the linear polarizer FIG. 7 shows transmittance spectra of transmitted light measured from a direction (oblique direction) inclined by 30 ° from the normal direction with a reference line in a plane forming an angle of 45 ° as an axis. While the almost complete black transmittance over substantially the entire region is approximately 1% or less of the visible light in the normal direction, when measured from the tilted direction, there is a wavelength transmittance that Do 3% or more Thus, it can be seen that coloring by the interference color occurs.
[Brief description of the drawings]
1 is a schematic sectional view showing an example of a protective film sticking linear polarizing plate according to the present invention.
It is a cross-sectional schematic view showing another example of the protective film sticking linear polarizing plate according to the present invention; FIG.
FIG. 3 is a schematic diagram showing an observation state in inspection of a linearly polarizing plate .
FIG. 4 is a schematic cross-sectional view showing a normal direction, a fast axis, and a direction tilted by 30 ° around the fast axis from the normal direction of the protective film that is uniaxially oriented .
FIG. 5 is a perspective view schematically showing an example of the relationship between the direction of the absorption axis of the linear polarizing plate and the direction of the slow axis of the protective film in the protective film-bonded linear polarizing plate according to the present invention .
6 is a diagram showing a transmittance spectrum of the protective film-attached linearly polarizing plate obtained in Example 1, wherein the horizontal axis represents wavelength and the vertical axis represents transmittance . FIG.
7 is a graph showing the transmittance spectrum of the protective film-attached linearly polarizing plate obtained in Comparative Example 1, wherein the horizontal axis indicates the wavelength and the vertical axis indicates the transmittance . FIG.
[Explanation of symbols]
1: linearly polarizing plate 11: linear polarizer absorption axis 12 of: polarizer film 13: protective film 2: a second protective film 21: second protective film in the slow axis 22: phase-advancing of the second protective film Axis 3: First protective film 31: Slow axis 4 of first protective film 4: Protective film-attached linear polarizing plate 5: Adhesive layer 6: Eye position 7 in inspection product: Inspection linear polarizing plate L0: Method linear direction L30: direction L1 tilted 30 ° from the normal direction to the phase advance axis, L 2: the oblique direction at the time of inspection

Claims (3)

On the adhesive layer of the linearly polarizing plate having an adhesive layer on one side, the slow axis is oriented in the range of 0 ± 15 ° with respect to the absorption axis of the linearly polarizing plate or 90 Having a first protective film made of polyethylene terephthalate that is attached to form an angle in the range of ± 15 °;
The other surface of the linearly polarizing plate is uniaxially oriented, and its slow axis forms an angle of 0 ° ± 15 ° or 90 ° ± 15 ° with respect to the absorption axis of the linearly polarizing plate. A protective film-attached linearly polarizing plate having a second protective film made of polyethylene terephthalate attached to the substrate. The protective film-attached linearly polarizing plate according to claim 1 , wherein the linearly polarizing plate has an adhesive layer on the other surface, and the second protective film is attached on the adhesive layer. First and second protective film is oriented uniaxially was measured from a direction inclined 30 ° retardation measured in the normal direction and (R0) from the normal direction to the phase advance axis of the protective film Letter The protective film-attached linearly polarizing plate according to claim 1 or 2 , wherein the ratio (R0 / R30) to the foundation (R30) is 1.5 or less.

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