JP6700964B2 - Polarizer - Google Patents

Description

  The present invention relates to a polarizing plate that can be used for various optical applications.

  2. Description of the Related Art In recent years, mobile terminals such as smartphones are rapidly becoming larger and slimmer in terms of design and portability. In order to realize driving for a long time with a limited thickness, polarizing plates used are also required to have higher brightness and thinner thickness.

  In order to solve such a demand, there has been proposed a polarizing plate in which a protective film made of a transparent resin, which is attached to both surfaces of a polarizer, is usually disposed on only one side, and a brightness enhancement film is further attached. For example, Patent Document 1 discloses a thin, high-brightness polarizing plate in which a protective film made of a transparent resin, a polarizer in which iodine is adsorbed and oriented on a polyvinyl alcohol film, a pressure-sensitive adhesive layer, and a brightness enhancement film are laminated in this order. It is disclosed.

JP, 2010-039458, A

However, as a result of the progress of thinning the polarizer, when the polarizing plate described in the cited document 1 is used in an environment where high temperature and low temperature are repeated, the polarizer is cracked.
Such cracking of the polarizer may be caused by, for example, the inclusion of foreign matter in the surface of the protective film during the manufacturing process of the polarizing plate, the foreign matter during lamination of the protective film, and handling of the polarizing plate. This may occur due to a scratch that has occurred near the part.

  With the thinning of polarizing plates in recent years, cracks in the polarizer are more likely to occur, and therefore a solution is required.

  Therefore, an object of the present invention is to provide a thin polarizing plate in which cracking of the polarizer is unlikely to occur. Another object of the present invention is to provide a polarizing plate in which occurrence of defective appearance such as cracking of a polarizer and light leakage is suppressed even when used in an environment where high temperature and low temperature are repeated.

The present invention includes the following.
[1]
A polarizing plate in which a first pressure-sensitive adhesive layer, a polarizer having a thickness of 10 μm or less, and a first protective film containing a cellulosic resin are laminated,
The first protective film has a scratch on at least one of the surface of the first protective film opposite to the polarizer and the surface of the first protective film on the polarizer side,
The scratches have a length of 0.001 to 500 μm, a width of 0.001 to 500 μm, and a depth of 0.001 to 10 μm, and a depth of 0.001 to 10 μm and an area of 0.001 to 1.0 mm ^2. A polarizing plate having at least one of the scratches.
[2]
The polarizing plate according to [1], wherein the first pressure-sensitive adhesive layer, the polarizer, and the first protective film are laminated in this order.
[3]
The said 1st protective film is a polarizing plate as described in [1] or [2] which has a surface on the opposite side to the said polarizer in the said 1st protective film.

  The polarizing plate of the present invention exhibits good polarization characteristics without causing light leakage or cracking of the polarizer even in an environment where high temperature and low temperature are repeated.

  Moreover, the polarizing plate of the present invention is a thin plate and is excellent in strength and durability.

FIG. 1 illustrates a schematic cross-sectional view of the layer structure of the polarizing plate of the present invention.

  Hereinafter, the polarizing plate according to the present invention will be described with reference to the drawings as appropriate, but the present invention is not limited to these embodiments.

  In the present invention, the polarizing plate is formed by laminating the first pressure-sensitive adhesive layer, the polarizer having a thickness of 10 μm or less, and the first protective film, and the order of laminating these is not particularly limited. In one embodiment, as shown in FIG. 1, the polarizing plate 100 of the present invention may have a configuration in which a first adhesive layer 11, a polarizer 12 and a first protective film 13 are laminated in this order. Thus, when the protective film is provided on only one side of the polarizer, cracking of the polarizer is likely to occur in an environment where high temperature and low temperature are repeated, but according to the present invention, cracking of the polarizer is effectively suppressed. obtain.

The polarizer of the present invention has a thickness of 10 μm or less and is a member having a function of converting light such as natural light into linearly polarized light. For example, the polarizer has a thickness of 8 μm or less. Moreover, the polarizer in the present invention may have a thickness of 2 μm or more. In one embodiment, the polarizer can have a thickness of 2 μm to 8 μm.
Conventionally, the thinner the polarizer, the more easily the influence of scratches present on the polarizing plate on the cracking of the polarizer is likely to occur. However, the present invention solves such a problem, and even a thin polarizer in the above range can exhibit excellent optical characteristics without causing cracks in the polarizing plate.

The first protective film in the present invention has a scratch on at least one of the surface of the first protective film opposite to the polarizer and the surface of the first protective film on the polarizer side. The scratch has a length of 0.001 to 500 μm, a width of 0.001 to 500 μm, and a depth of 0.001 to 10 μm, and a depth of 0.001 to 10 μm and an area of 0.001 to 1.0 mm ² . At least one of the wounds.
Since the first protective film has a scratch of such a size, the polarizing plate of the present invention has good polarization characteristics without causing light leakage or cracking even in an environment where high temperature and low temperature are repeated. Can be shown. Although the reason is not clear, the first protective film has the above-mentioned scratches, and thus the difference between the behavior of the first protective film and the behavior of the polarizer in an environment where high temperature and low temperature are repeated becomes small, The force applied to the polarizer can be reduced. Furthermore, when the first protective film in the polarizing plate has a scratch in the above range on the surface thereof, when a thermal shock is applied in an environment where high temperature and low temperature are repeated, the scratch inside the polarizing plate causes the scratch. It is considered that this is because the stress can easily escape.
When the first protective film contains a cellulose resin, the polarizing plate of the present invention can further exhibit good polarization characteristics without causing light leakage or cracking. On the other hand, a scratch exceeding the above range may itself cause deterioration of visibility.

  Here, the shape of the “scratch” in the present invention is not limited as long as the size of the scratch is included in the above range. Examples include linear scratches, polygonal scratches, curved scratches, scratches that have multiple scratches (for example, scratches), and dents (for example, cylinders, polygonal prisms, cones, polygonal cones, and taper shapes). Be done.

  Further, in the “wound” in the present invention, the dimensions such as the depth and the width of the flaw may vary as long as the dimension of the flaw is included in the above range. For example, the wound may have a depth of 6 μm and another wound may have a depth of 7 μm.

  A conventional method is used to measure the size of such a scratch, and examples thereof include measurement with a laser beam and measurement with a microscope.

  The size of the scratch according to the present invention is the maximum value of each side in the largest scratch existing on the first protective film. For example, in the present invention, the flaw having the maximum total value of the length, width, and thickness of the flaw is assumed to be the largest flaw.

  Further, the area of scratches means the area within a plane parallel to the plane of the first protective film. That is, the area of the scratch does not need to consider the depth of the scratch, and the area of the scratch observed on the plane of the first protective film may be simply measured. Moreover, the area of the scratch can be calculated using a conventional method.

  The position where the scratch is present is not particularly limited. For example, scratches may be randomly present on the entire surface of the film. For example, the scratch is present on the surface end portion of the first protective film.

  For example, the scratch is present on the surface of the first protective film opposite to the polarizer. In this case, the scratch has, for example, a length of 0.001 to 500 μm, a width of 0.001 to 500 μm, and a depth of 0.001 to 10 μm.

Moreover, at least one scratch may be present on the surface of the first protective film, and may be present at a density of 0.0001 to 0.001 per 1 mm ² . For example, in the case of a 65 mm×130 mm size polarizing plate, there may be about 0.8 to about 8.5 scratches. If the number of scratches exceeds the above range, the haze value of the polarizing plate becomes high, and the optical characteristics of the polarizing plate may become insufficient.

  Further, the shape of the scratch formed in the depth direction of the first protective film may be one formed in a direction perpendicular to the plane of the first protective film, and may be formed with respect to the plane of the first protective film. It may be formed in an oblique direction, or may be a combination of these.

  The method for forming the scratch is not particularly limited, and for example, the inclusion of foreign matter on the surface of the protective film in the process of manufacturing the polarizing plate, the foreign matter during the lamination of the protective film, and the handling of the polarizing plate may affect the surface of the polarizing plate. It is also possible to use a scratch generated near the end. In addition, when manufacturing the polarizing plate, for example, a predetermined scratch may be provided on the surface end portion of the first protective film. In this case, a scratch may be provided on the surface end of the first protective film by using a scratch type hardness meter or the like.

  The size of the scratches in the present invention may be a combination of the sizes described below as long as they fall within the above range.

  The length of the scratch is 0.001 to 500 μm, and in another aspect, 0.001 to 400 μm. In the case of a bent scratch or a curved scratch, the length of the scratch is indicated by the total length of the scratches.

  The width of the scratch is 0.001 to 500 μm, and in another aspect, 0.001 to 400 μm.

  The depth of the scratch is 0.001 to 10 μm, and in another aspect, 1 to 10 μm.

For example, in the case of a concave scratch, the size of the scratch may be calculated by the area of the scratch without measuring the length, width, etc. of the scratch. In this case, scratches, has an area of 0.01 to 1.0 mm ^2, for example, it has an area of 0.1～0.50Mm ^2, the area of 0.1～0.30Mm ² in another embodiment Have.

  In another embodiment, the wound has dimensions of 0.001 to 500 μm in length, 0.001 to 500 μm in width, and 0.001 to 10 μm in depth.

In yet another embodiment, the wound is 0.001-10 μm deep and has an area of 0.01-1.0 mm ² .

[Polarizer]
The polarizer according to the present invention generally has a transmission axis and an absorption axis. The transmission axis direction of such a polarizer is understood as a vibration direction of transmitted light when natural light is transmitted through the polarizer. On the other hand, the absorption axis of the polarizer is orthogonal to the transmission axis of the polarizer. In addition, the polarizer may generally be a stretched film, and the absorption axis direction of the polarizer coincides with the stretching direction.

  In the present invention, the term “direction parallel to the transmission axis direction of the polarizer” indicates a direction that is parallel or substantially parallel (with an angle of ±7 degrees or less) to the transmission axis direction of the polarizer described above. ..

  The polarizer may be a uniaxially stretched polyvinyl alcohol resin layer in which a dichroic dye is adsorbed and oriented.

  As the polyvinyl alcohol resin, saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable therewith. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamide having an ammonium group.

  The saponification degree of the polyvinyl alcohol resin may be in the range of 80 mol% or more. For example, it is in the range of 90 mol% or more, and in another embodiment, 95 mol%. The polyvinyl alcohol-based resin may be a modified polyvinyl alcohol that is partially modified. For example, the polyvinyl alcohol-based resin may be an olefin such as ethylene and propylene; an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, and crotonic acid. Those which are modified with an alkyl ester of unsaturated carboxylic acid, acrylamide or the like. The average degree of polymerization of the polyvinyl alcohol-based resin is, for example, 100 to 10000, 1500 to 8000 in another aspect, and 2000 to 5000 in yet another aspect.

  For the polarizer, for example, a raw film made of polyvinyl alcohol resin is uniaxially stretched, dyed with a dichroic dye (dyeing treatment), treated with an aqueous solution of boric acid (boric acid treatment), and washed with water (washing with water). Treatment), and finally dried to produce.

  The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before dyeing with the dichroic dye, simultaneously with dyeing with the dichroic dye, or after dyeing with the dichroic dye. Good. When uniaxial stretching is performed after dyeing with a dichroic dye, this uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. Of course, it is also possible to carry out uniaxial stretching in these plural stages. In order to carry out uniaxial stretching, stretching may be carried out between rolls having different peripheral speeds, or stretching may be carried out by a method of sandwiching by hot rolls. Further, it may be dry stretching in which the stretching is performed in the atmosphere, or wet stretching in which the stretching is performed in a state swollen with a solvent. The final draw ratio of the polyvinyl alcohol-based resin film is usually about 4 to 8 times.

  In the dyeing treatment, the polyvinyl alcohol resin film is dyed with a dichroic dye, and the dichroic dye is adsorbed on the film. For the dyeing treatment, for example, the polyvinyl alcohol-based resin film may be immersed in an aqueous solution containing a dichroic dye. Specifically, iodine or a dichroic dye is used as the dichroic dye.

  When iodine is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide and dyeing is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 0.5 parts by mass per 100 parts by mass of water, and the content of potassium iodide is usually 0.5 to 10 parts by mass per 100 parts by mass of water. It is about a part. The temperature of this aqueous solution is usually about 20 to 40° C., and the immersion time in this aqueous solution is usually about 30 to 300 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye and dyeing is usually employed. The content of the dichroic dye in this aqueous solution is usually about 1×10 ⁻³ to 1×10 ⁻² parts by mass per 100 parts by mass of water. This aqueous solution may contain an inorganic salt such as sodium sulfate. The temperature of this aqueous solution is usually about 20 to 80° C., and the immersion time in this aqueous solution is usually about 30 to 300 seconds.

  The boric acid treatment is performed, for example, by immersing the dyed polyvinyl alcohol-based resin film in an aqueous boric acid solution. The content of boric acid in the boric acid aqueous solution is usually about 2 to 15 parts by mass, for example, 5 to 12 parts by mass, per 100 parts by mass of water. When iodine is used as the dichroic dye, the aqueous boric acid solution may contain potassium iodide. The content of potassium iodide in the aqueous boric acid solution is usually about 2 to 20 parts by mass, for example, 5 to 15 parts by mass, per 100 parts by mass of water. The immersion time of the film in the aqueous boric acid solution is usually about 100 to 1200 seconds, for example, 150 seconds or more, and in another embodiment, 200 seconds or more. On the other hand, the immersion time is, for example, 600 seconds or less, and in another aspect, 400 seconds or less. The temperature of the boric acid aqueous solution is usually 50°C or higher, for example, 50 to 85°C. Sulfuric acid, hydrochloric acid, acetic acid, ascorbic acid, etc. may be added to the aqueous boric acid solution as pH adjusters.

  The polyvinyl alcohol-based resin film after the boric acid treatment is usually washed with water. The water washing treatment is performed, for example, by immersing the polyvinyl alcohol-based resin film treated with boric acid in water. After washing with water, it is dried to obtain a polarizer. The temperature of water in the water washing treatment is usually about 5 to 40°C, and the immersion time is usually about 2 to 120 seconds. Drying performed thereafter is usually performed using a hot air dryer or a far infrared heater. The drying temperature is usually 40 to 100° C., and the drying time is usually 120 to 600 seconds.

[Protective film]
In one embodiment, the first protective film and the polarizer are attached via an adhesive layer. The thickness of the adhesive layer is, for example, 0.001 μm to 10 μm. As the adhesive layer, those known in the art can be used. As the adhesive forming the adhesive layer, a water-based adhesive or an active energy ray-curable adhesive can be used. By sticking the first protective film and the polarizer via the adhesive layer, light leakage and cracking of the polarizer can be suppressed even in an environment where high temperature and low temperature are repeated.

  The thickness of the first protective film is 5 to 90 μm, for example, 60 μm or less, and in another aspect, 30 μm or less. By having the thickness in such a range, the polarizing plate of the present invention can have excellent mechanical properties and optical properties.

For example, the first protective film may have a dimensional change rate within a predetermined range in the absorption axis direction and the transmission axis direction of the polarizer.
(Rate of dimensional change in the absorption axis direction of the polarizer)
For example, in the direction parallel to the absorption axis direction of the polarizer (may be described as MD direction) of the first protective film, the dimensional change rate after 1 hour under the condition of 85° C. relative humidity 5%, When the MD direction dimensional change rate (85° C.) of the protective film is set, the MD direction dimensional change rate (85° C.) of the protective film is preferably 0.06 to 0.25, and 0.06 to 0. It is more preferably 20 and even more preferably 0.06 to 0.15.
By having the dimensional change rate in such a range, cracking of the polarizer in an environment where high temperature and low temperature are repeated can be more effectively suppressed.

  On the other hand, in the direction parallel to the absorption axis direction of the polarizer (MD direction) of the protective film, the rate of dimensional change after 0.5 hours under the condition of 30° C. and 95% relative humidity is the MD direction dimension of the protective film. When the rate of change (30° C.) is set, the dimensional change rate (30° C.) in the MD direction of the protective film is preferably −0.25 to 0.00, and is −0.15 to 0.00. Is more preferable. By having the dimensional change rate in such a range, cracking of the polarizer in an environment where high temperature and low temperature are repeated can be more effectively suppressed.

In the present invention, the dimensional change rate in the MD direction after 1 hour has been measured under the conditions of 85° C. and 5% relative humidity according to the following formula.
Here, for example, in the present invention, the dimensional change rate after 1 hour has passed in the direction parallel to the absorption axis direction of the polarizer of the protective film under the condition of 85° C. and 5% relative humidity as the MD direction of the protective film. It may be described as a dimensional change rate (85°C).

MD direction dimensional change rate of protective film (85° C.)=[(L0-L85)/L0]×100
[In the formula, L0 means a film size of the cut film in a direction (MD direction) parallel to the absorption axis direction of the polarizer (long direction or width direction,
L85 means the film size in the direction (MD direction) (longitudinal direction or width direction) parallel to the absorption axis direction of the polarizer after 1 hour under the condition of 85° C. and 5% relative humidity. ]
For example, when the MD direction dimension (L0) is measured at the time of film cutting, the MD direction dimension (L85) of the film is measured even after standing for 1 hour under the condition of 85° C. and 5% relative humidity. Calculate the rate of change. Moreover, when the dimension (L0) in the direction parallel to the absorption axis direction of the polarizer (MD direction) in the protective film obtained by removing the polarizer and the like from the polarizing plate is measured after producing the polarizing plate, the relative humidity is 85° C. Even after standing for 1 hour under the condition of 5%, the dimension (L85) in the direction (MD direction) parallel to the absorption axis direction of the polarizer is measured, and the dimensional change rate is calculated.

The dimensional change rate (85° C.) calculated in this manner means a contraction if it is a positive value, and an expansion if it is a negative value.
In one aspect, the direction (MD direction) in the first protective film, which is parallel to the absorption axis direction of the polarizer, may be the stretching direction of the first protective film, or may be the lengthwise direction. Good.

Similarly to the above, in the present invention, the calculation of the dimensional change rate after 0.5 hours under the condition of 30° C. and 95% relative humidity is as follows. It is measured according to the following formula.
For example, in the present invention, in the direction parallel to the absorption axis direction of the polarizer (MD direction) of the protective film, the MD dimensional change rate after 0.5 hours under the condition of 30° C. relative humidity 95%, It may be referred to as the MD direction dimensional change rate (30° C.) of the protective film.

MD dimensional change rate (30° C.)=[(L0 ₃₀ −L30)/L0]×100
[In the formula, L0 ₃₀ means a film dimension after measuring a dimensional change rate (85° C.) in a direction (MD direction) parallel to the absorption axis direction of the polarizer (longitudinal direction or width direction),
L30 means the film size in the direction (MD direction) (longitudinal direction or width direction) parallel to the absorption axis direction of the polarizer after 0.5 hour under the condition of 30° C. and 95% relative humidity. ]
For example, after measuring the dimensional change rate (85 ° C.), the temperature 23 ° C., after standing for 15 minutes at 55% humidity may measure _{L0 30.}
The MD-direction dimensional change rate (30° C.) calculated in this manner has a positive value, which means contraction, and a negative value, which means expansion.

  In the protective film of the present invention, the dimensional change rate (85° C.) and the dimensional change rate (30° C.) may have the same sign (positive, negative or zero) or different signs. Good. In one aspect, the sign of the dimensional change rate (85° C.) and the sign of the dimensional change rate (30° C.) are different signs.

  In the polarizing plate of the present invention, since the first protective film has a dimensional change rate in such a range, cracks and light leakage that occur in the polarizer under high temperature and high humidity conditions can be further suppressed, and the durability is further improved. Can have In addition, a polarizing plate having a protective film having such characteristics can make the polarizer thin, and even when a physical change such as a dent occurs on the surface of the protective film, cracking of the polarizer is caused. Can be suppressed.

(Rate of dimensional change in the direction perpendicular to the absorption axis of the polarizer)
For example, the condition of 85% relative humidity 5% in the direction perpendicular to the absorption axis direction of the polarizer of the first protective film, that is, in the direction parallel to the transmission axis direction of the polarizer (may be described as TD direction). When the dimensional change rate after one hour has passed is the TD dimensional change rate (85° C.) of the protective film, the TD dimensional change rate (85° C.) of the protective film is 0.05 to 0.25. Is preferable, and 0.05 to 0.20 is more preferable. By having the dimensional change rate in such a range, cracking of the polarizer in an environment where high temperature and low temperature are repeated can be more effectively suppressed.

  On the other hand, in the direction parallel to the transmission axis direction of the polarizer (TD direction) of the protective film, the dimensional change rate after 0.5 hours under the condition of 30° C. and 95% relative humidity is the TD direction dimension of the protective film. When the rate of change (30° C.) is set, the rate of dimensional change in the TD direction (30° C.) of the protective film is preferably −0.25 to 0.00, and is −0.20 to 0.00. Is more preferable. By having the dimensional change rate in such a range, cracking of the polarizer in an environment where high temperature and low temperature are repeated can be more effectively suppressed.

  For example, the absolute value of the difference between the TD dimensional change rate of the protective film (85° C.) and the TD dimensional change rate of the protective film (30° C.) is preferably 0.20 to 0.50, It is more preferably 0.03 to 0.30. By having the absolute value of the difference in the dimensional change rate in such a range, cracking of the polarizer in an environment where high temperature and low temperature are repeated can be suppressed more effectively.

  In the polarizing plate of the present invention, since the first protective film has the dimensional change rate and the absolute value of the difference in the dimensional change rate in such a range, cracks and light leakage that occur in the polarizer under high temperature and high humidity conditions can be prevented. It can be further suppressed and can have further excellent durability. In addition, a polarizing plate having a protective film having such characteristics can make the polarizer thin, and even when a physical change such as a dent occurs on the surface of the protective film, cracking of the polarizer is caused. Can be suppressed.

The first protective film is a film containing a cellulosic resin. In one aspect, the first protective film is a film containing a cellulosic resin as a main component, as described below. The first protective film may be a single layer film containing a resin such as a cellulosic resin as a main component or a multilayer film having a layer containing a resin such as a cellulosic resin as a main component.
Here, the term “main component” means an amount of more than 50 parts by mass, 80 parts by mass or more in another embodiment, and 90 parts by mass or more in another embodiment, with respect to 100 parts by mass of the resin component in the first protective film. It means a resin component contained in the first protective film.
The monolayer film or the multilayer film may be surface-treated on both sides or one side.
This surface treatment may be surface modification by corona treatment, saponification treatment, heat treatment, ultraviolet irradiation, electron beam irradiation or the like. Alternatively, a thin film may be formed by coating or vapor deposition of polymer or metal.

  For example, the first protective film may be formed with a surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer and an antifouling layer. As a method for forming the surface treatment layer on the surface of the protective film, a known method can be used. For example, the first protective film may have a hard coat layer on the surface opposite to the polarizer. For example, when the first protective film has the hard coat layer, it is possible to suppress the occurrence of scratches and the like on the surface of the polarizing plate. In the present invention, the polarizing plate is not affected as long as the dimension such as scratches is within the range of the present invention. However, usually, scratches often extend over a wide range, and it is preferable that the occurrence of scratches can be suppressed.

In one embodiment, the hard coat layer provided on the surface of the first protective film opposite to the polarizer has a thickness of 1 to 10 µm. For example, the thickness of the hard coat layer is smaller than the thickness of the first protective film.
In another aspect, the ratio of the thickness of the hard coat layer to the thickness of the first protective film is in the range of 0.9:1 to 0.01:1.
When the ratio of the thickness of the hard coat layer to the thickness of the first protective film is in the above range, the obtained polarizing plate is in an environment where high temperature conditions and low temperature conditions are repeated (for example, under a thermal shock environment). Since the protective film suppresses the stress such as shrinkage that occurs in the polarizer and cracks are less likely to occur in the polarizer, the polarizing plate has further excellent durability.

When the first protective film has a surface treatment layer such as a hard coat layer, the first protective film is, for example, on the surface treatment layer surface disposed on the surface of the first protective film opposite to the polarizer, For example, a scratch having a length of 0.001 to 500 μm, a width of 0.001 to 500 μm and a depth of 0.001 to 10 μm, and a depth of 0.001 to 10 μm and an area of 0 on the visible side surface of the surface treatment layer. It may have at least one of the scratches being 0.001 to 1.0 mm ² .

  When the first protective film has a surface treatment layer such as a hard coat layer, a commercially available protective film that has been subjected to a hard coat treatment may be used. In this case, the scratch according to the present invention may be provided in the surface treatment layer, and for example, the scratch may be provided on the visible side surface of the surface treatment layer.

The first protective film may be a transparent resin film composed of a thermoplastic resin containing a cellulosic resin. The cellulose-based resin is, for example, a cellulose ester-based resin such as cellulose triacetate, cellulose diacetate, cellulose tripropionate, or cellulose dipropionate.
In addition to the cellulose resin, the first protective film is made of another thermoplastic resin, for example, a chain polyolefin resin such as a polypropylene resin and a polyolefin resin such as a cyclic polyolefin resin; polyethylene terephthalate, polyethylene. A polyester resin such as naphthalate and polybutylene terephthalate; a polycarbonate resin; a (meth)acrylic resin selected from a polymethylmethacrylate resin; or a mixture of at least two or more thereof may be included. Moreover, you may use the copolymer of at least 2 or more types of monomers which comprise the said resin. In one aspect, the mass ratio of the cellulose resin in the entire protective film is 50% by mass or more as an example, 70% by mass or more in another aspect, and 90 in still another aspect, when the entire protective film is 100% by mass. It is at least mass%.

  The cellulose ester resin is usually an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, it is also possible to use a copolymerized product thereof or a product in which a part of the hydroxyl groups is modified with another substituent. Among these, for example, cellulose triacetate (triacetyl cellulose:TAC) can be selected. Many products of cellulose triacetate are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of cellulose triacetate are trade names of "Fujitac (registered trademark) TD80", "Fujitac (registered trademark) TD80UF", and "Fujitac (registered trademark) TD80UZ" sold by Fuji Film Co., Ltd. And "Fujitac (registered trademark) TD40UZ", TAC films "KC8UX2M", "KC2UA" and "KC4UY" manufactured by Konica Minolta Co., Ltd.

  For example, the first protective film containing a cellulosic resin may be obtained by subjecting the produced film to a stretching treatment. Stretching may be required to obtain a film having desired optical properties and mechanical properties. Examples of the stretching treatment include uniaxial stretching and biaxial stretching. Examples of the stretching direction include the machine direction (MD) of the unstretched film, the direction (TD) orthogonal to the machine direction, and the direction oblique to the machine direction (MD). The biaxial stretching may be simultaneous biaxial stretching in which two stretching directions are simultaneously performed, or sequential biaxial stretching in which the stretching is performed in a predetermined direction and then in another direction.

  Cyclic polyolefin resin is a general term for resins polymerized with cyclic olefin as a polymerization unit, and is described in, for example, JP-A 1-240517, JP-A 3-14882, and JP-A 3-122137. Examples of the resin include Specific examples of the cyclic polyolefin-based resin include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of chain olefins such as ethylene and propylene and cyclic olefins (typically Random copolymers), graft polymers obtained by modifying these with unsaturated carboxylic acids or their derivatives, and their hydrides. Above all, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer as the cyclic olefin is preferably used.

  Various products of cyclic polyolefin resins are commercially available. Examples of commercially available cyclic polyolefin resins are "TOPAS" (registered trademark), which is manufactured by TOPAS ADVANCED POLYMERS GmbH under the trade name and sold by Polyplastics Co., Ltd. in Japan, JSR Corporation. "Arton" (registered trademark) sold by Zeon Corporation, "Zeonoa" (registered trademark) and "Zeonex" (registered trademark) sold by Zeon Corporation, and "Apel" sold by Manabu Mitsui Co., Ltd. (Registered trademark).

  Moreover, you may use the commercial item of the cyclic polyolefin resin film formed into a film as a protective film. Examples of commercially available products are "Arton Film" ("Arton" is a registered trademark of the company) sold by JSR Corporation and "ESCINA" (marketed by Sekisui Chemical Co., Ltd.) Registered trademark) and "SCA40", "Zeonor film" (registered trademark) sold by Nippon Zeon Co., Ltd., and the like.

  Polymethacrylic acid ester and polyacrylic acid ester (hereinafter, polymethacrylic acid ester and polyacrylic acid ester may be collectively referred to as (meth)acrylic resin) are easily available from the market.

  Examples of the (meth)acrylic resin include homopolymers of methacrylic acid alkyl ester or acrylic acid alkyl ester, and copolymers of methacrylic acid alkyl ester and acrylic acid alkyl ester. Specific examples of the methacrylic acid alkyl ester include methyl methacrylate, ethyl methacrylate and propyl methacrylate, and specific examples of the acrylic acid alkyl ester include methyl acrylate, ethyl acrylate and propyl acrylate. As such a (meth)acrylic resin, a commercially available general-purpose (meth)acrylic resin can be used. As the (meth)acrylic resin, a so-called impact resistant (meth)acrylic resin may be used.

  The (meth)acrylic resin is usually a polymer mainly composed of methacrylic acid ester. The methacrylic resin may be a homopolymer of one kind of methacrylic acid ester, or a copolymer of methacrylic acid ester and other methacrylic acid ester or acrylic acid ester. Examples of the methacrylic acid ester include alkyl methacrylate such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, and the number of carbon atoms of the alkyl group is usually about 1 to 4. Also, use cycloalkyl methacrylate such as cyclopentyl methacrylate, cyclohexyl methacrylate, and methacryl, aryl methacrylate such as phenyl methacrylate, cycloalkyl alkyl methacrylate such as cyclohexylmethyl methacrylate, and aralkyl methacrylate such as benzyl methacrylate. You can also

  Examples of the other polymerizable monomer that can form the (meth)acrylic resin include acrylic acid ester, and polymerizable monomers other than methacrylic acid ester and acrylic acid ester. As the acrylate ester, an acrylate alkyl ester can be used, and specific examples thereof include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and acrylic. It includes acrylic acid alkyl esters in which the alkyl group has 1 to 8 carbon atoms such as t-butyl acid, 2-ethylhexyl acrylate, cyclohexyl acrylate, and 2-hydroxyethyl acrylate. The alkyl group has, for example, 1 to 4 carbon atoms. In the (meth)acrylic resin, one type of acrylic acid ester may be used alone, or two or more types may be used in combination.

  Examples of the polymerizable monomer other than the methacrylic acid ester and the acrylic acid ester include a monofunctional monomer having one polymerizable carbon-carbon double bond in the molecule and a polymerizable carbon-carbon double bond in the molecule. Examples thereof include polyfunctional monomers having at least two, but monofunctional monomers are preferably used. Specific examples of monofunctional monomers include styrene-based monomers such as styrene, α-methylstyrene, vinyltoluene, halogenated styrene, and hydroxystyrene; vinyl cyanide such as acrylonitrile and methacrylonitrile; acrylic acid, methacrylic acid, and anhydrous. Unsaturated acids such as maleic acid and itaconic anhydride; maleimides such as N-methylmaleimide, N-cyclohexylmaleimide and N-phenylmaleimide; allyl alcohols such as methacrylic alcohol and allyl alcohol; vinyl acetate, vinyl chloride, ethylene, propylene, Other monomers such as 4-methyl-1-pentene, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, N-vinyl carbazole are included.

  Specific examples of polyfunctional monomers include polyunsaturated carboxylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate, butanediol dimethacrylate, and trimethylolpropane triacrylate; allyl acrylate, allyl methacrylate, allyl cinnamate. Alkenyl esters of unsaturated carboxylic acids such as; polyalkenyl esters of polybasic acids such as diallyl phthalate, diallyl maleate, triallyl cyanurate, triallyl isocyanurate, and aromatic polyalkenyl compounds such as divinylbenzene. The polymerizable monomers other than the methacrylic acid ester and the acrylic acid ester may be used alone or in combination of two or more.

  The preferred monomer composition of the (meth)acrylic resin is, based on the total amount of monomers, methacrylic acid alkyl ester of 50 to 100% by mass, acrylic acid alkyl ester of 0 to 50% by mass, and other polymerizable monomers of 0 to 100% by mass. 50% by mass, and in another embodiment, 50 to 99.9% by mass of methacrylic acid alkyl ester, 0.1 to 50% by mass of acrylic acid alkyl ester, and 0 to 49.9% by mass of polymerizable monomer other than these. Is.

  Further, the (meth)acrylic resin may have a ring structure in the polymer main chain since it can enhance the durability of the film. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure or a lactone ring structure. Specific examples thereof include cyclic acid anhydride structures such as glutaric anhydride structure and succinic anhydride structure, cyclic imide structures such as glutarimide structure and succinimide structure, and lactone ring structures such as butyrolactone and valerolactone. The glass transition temperature of the (meth)acrylic resin can be increased as the content of the ring structure in the main chain is increased. The cyclic acid anhydride structure and the cyclic imide structure are introduced by copolymerizing a monomer having a cyclic structure such as maleic anhydride and maleimide, and the cyclic acid anhydride structure is introduced by dehydration/demethanol condensation reaction after polymerization. It can be introduced by a method, a method of reacting an amino compound to introduce a cyclic imide structure, or the like. A resin (polymer) having a lactone ring structure is prepared by preparing a polymer having a hydroxyl group and an ester group in a polymer chain, and then heating the hydroxyl group and the ester group in the obtained polymer to a necessary amount. Accordingly, it can be obtained by a method of forming a lactone ring structure by cyclocondensation in the presence of a catalyst such as an organic phosphorus compound.

  The polymer having a hydroxyl group and an ester group in the polymer chain is, for example, 2-(hydroxymethyl)methyl acrylate, 2-(hydroxymethyl)ethyl acrylate, 2-(hydroxymethyl)isopropyl acrylate, 2- It can be obtained by using (meth)acrylic acid ester having a hydroxyl group and an ester group such as n-butyl (hydroxymethyl)acrylate and t-butyl 2-(hydroxymethyl)acrylate as a part of the monomer. .. A more specific method for preparing a polymer having a lactone ring structure is described in, for example, JP-A 2007-254726.

  A (meth)acrylic resin can be prepared by radically polymerizing a monomer composition containing the above monomers. The monomer composition can contain a solvent and a polymerization initiator as needed.

  The (meth)acrylic resin may contain a resin other than the above-mentioned (meth)acrylic resin. The content of the other resin is, for example, 0 to 70% by mass, 0 to 50% by mass in another embodiment, and 0 to 30% by mass in yet another embodiment. The resin is, for example, an olefin polymer such as polyethylene, polypropylene, an ethylene-propylene copolymer, or poly(4-methyl-1-pentene); a halogen-containing polymer such as vinyl chloride or a chlorinated vinyl resin; polystyrene, styrene. -Styrene-based polymers such as methyl methacrylate copolymer and styrene-acrylonitrile copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyarylate composed of aromatic diol and aromatic dicarboxylic acid; polylactic acid, Biodegradable polyester such as polybutylene succinate; polycarbonate; polyamide such as nylon 6, nylon 66, nylon 610; polyacetal; polyphenylene oxide; polyphenylene sulfide; polyether ether ketone; polyether nitrile; polysulfone; polyether sulfone; poly It can be oxypentylene; polyamideimide and the like.

  The (meth)acrylic resin may contain rubber particles from the viewpoint of improving impact resistance and film-forming property of the film. The rubber particles may be particles composed only of a layer exhibiting rubber elasticity, or may be particles having a multilayer structure having a layer exhibiting rubber elasticity and another layer. Examples of the rubber elastic body include an olefin elastic polymer, a diene elastic polymer, a styrene-diene elastic copolymer, and an acrylic elastic polymer. Among them, an acrylic elastic polymer is preferably used from the viewpoint of light resistance and transparency.

  The acrylic elastic polymer may be a polymer mainly composed of alkyl acrylate, that is, a polymer containing 50% by mass or more of structural units derived from alkyl acrylate based on the total amount of monomers. The acrylic elastic polymer may be a homopolymer of alkyl acrylate, and contains 50% by mass or more of structural units derived from alkyl acrylate and 50% by mass or less of structural units derived from other polymerizable monomers. It may be a copolymer.

  As the alkyl acrylate constituting the acrylic elastic polymer, one having an alkyl group having 4 to 8 carbon atoms is usually used. Examples of the above other polymerizable monomers include, for example, alkyl methacrylate such as methyl methacrylate and ethyl methacrylate; styrene-based monomers such as styrene and alkylstyrene; unsaturated nitrile such as acrylonitrile and methacrylonitrile. Monofunctional monomers, and alkenyl esters of unsaturated carboxylic acids such as allyl (meth)acrylate and methacrylic (meth)acrylate; dialkenyl esters of dibasic acids such as diallyl maleate; alkylene glycol di(meth) It is a polyfunctional monomer such as unsaturated carboxylic acid diester of glycol such as acrylate.

  The rubber particles containing the acrylic elastic polymer are preferably particles having a multi-layer structure having a layer of the acrylic elastic polymer. Specifically, a two-layer structure having a hard polymer layer mainly containing alkyl methacrylate on the outside of the acrylic elastic polymer layer, or an alkyl methacrylate on the inside of the acrylic elastic polymer layer. A three-layer structure having a hard polymer layer mainly composed of

  The example of the monomer composition in the polymer mainly composed of alkyl methacrylate constituting the hard polymer layer formed outside or inside the acrylic elastic polymer layer is given as an example of the (meth)acrylic resin. This is the same as the example of the monomer composition of the polymer mainly containing alkyl methacrylate, and particularly, the monomer composition mainly containing methyl methacrylate is preferably used. Such acrylic rubber elastic particles having a multilayer structure can be produced, for example, by the method described in JP-B-55-27576.

  From the viewpoint of the film-forming property of the (meth)acrylic resin, the impact resistance of the film, and the slipperiness of the film surface, the rubber particles have a rubber elastic layer (acrylic elastic polymer layer) included therein. The average particle size is preferably in the range of 10 to 350 nm. The average particle size is, for example, 30 nm or more, and in another aspect, 50 nm or more. On the other hand, the particle size is, for example, 300 nm or less, and in another aspect, 280 nm or less.

  The average particle size of the rubber particles up to the rubber elastic layer (the layer of the acrylic elastic polymer) is measured as follows. That is, when such rubber particles are mixed with a (meth)acrylic resin to form a film, and the cross section thereof is dyed with an aqueous solution of ruthenium oxide, only the rubber elastic layer is colored and observed in a substantially circular shape. No (meth)acrylic resin is dyed. Therefore, a thin section is prepared from a cross section of the film thus dyed using a microtome or the like, and this is observed with an electron microscope. Then, 100 randomly dyed rubber particles are extracted, the particle diameter of each (diameter up to the rubber elastic layer) is calculated, and the number average value thereof is taken as the average particle diameter. Since the measurement is performed by such a method, the obtained average particle size is a number average particle size.

  When the outermost layer is a hard polymer mainly composed of methyl methacrylate and the rubber elastic layer (the layer of the acrylic elastic polymer) is encased therein, the outermost layer is a rubber particle. ) When mixed with the acrylic resin, the outermost layer of the rubber particles is mixed with the matrix (meth)acrylic resin. Therefore, when the cross section is dyed with ruthenium oxide and observed with an electron microscope, the rubber particles are observed as particles excluding the outermost layer. Specifically, when the inner layer is an acrylic elastic polymer and the outer layer is a rubber particle having a two-layer structure which is a hard polymer mainly containing methyl methacrylate, the acrylic elastic polymer portion of the inner layer is used. Are stained and observed as particles having a monolayer structure. In addition, the innermost layer is a hard polymer mainly composed of methyl methacrylate, the intermediate layer is an acrylic elastic polymer, and the outermost layer is a hard polymer mainly composed of methyl methacrylate. In the case of rubber particles, the center portion of the particles in the innermost layer is not dyed, and only the acrylic elastic polymer portion of the intermediate layer is observed as a two-layer structure particle.

  From the viewpoint of the film-forming property of the (meth)acrylic resin, the impact resistance of the film, and the slipperiness of the film surface, the rubber particles are the total amount of the (meth)acrylic resin constituting the (meth)acrylic resin film. Can be blended in a proportion of 3% by mass or more and 60% by mass or less. If the rubber elastic body particles are more than 60% by mass, the dimensional change of the film becomes large and the heat resistance deteriorates. On the other hand, when the rubber elastic body particles are less than 3% by mass, the heat resistance of the film is good, but the winding property during film formation is poor and the productivity may be reduced. In the present invention, when a particle having a multi-layered structure having a layer showing rubber elasticity and another layer is used as the rubber elastic body particle, the mass of the portion consisting of the layer showing rubber elasticity and the layer inside thereof is used. , And the mass of the rubber elastic particles. For example, when the above-mentioned acrylic rubber elastic particles having a three-layer structure are used, the total mass of the acrylic rubber elastic polymer portion of the intermediate layer and the hard polymer portion mainly composed of methyl methacrylate of the innermost layer Is the mass of the rubber elastic particles. When the above acrylic rubber elastic particles having a three-layer structure are dissolved in acetone, the acrylic rubber elastic polymer portion of the intermediate layer and the hard polymer portion mainly composed of methyl methacrylate of the innermost layer are insoluble. Therefore, the total mass ratio of the intermediate layer and the innermost layer in the acrylic rubber elastic particle having a three-layer structure can be easily obtained.

  When the (meth)acrylic resin film contains rubber particles, the (meth)acrylic resin composition containing the rubber particles used in the production of the film is melt-kneaded with the (meth)acrylic resin and the rubber particles. It can be obtained by a method in which rubber particles are first produced and then a monomer composition as a raw material of a (meth)acrylic resin is polymerized in the presence of the rubber particles.

  A conventionally known film forming method can be adopted for producing the (meth)acrylic resin film. The (meth)acrylic resin film may have a multi-layered structure, and the (meth)acrylic resin film having a multi-layered structure may be variously known methods such as a method using a feed block and a method using a multi-manifold die. Can be used. Among them, for example, a method of laminating via a feed block, multi-layer melt extrusion molding from a T die, and contacting at least one surface of the obtained laminated film-like material with a roll or a belt to form a film, a film having a good surface property It is preferable because it can be obtained. In particular, from the viewpoint of improving the surface smoothness and the surface gloss of the (meth)acrylic resin film, the film is obtained by bringing both surfaces of the laminated film-like product obtained by the multilayer melt extrusion molding into contact with the roll surface or the belt surface. Is preferred. In the roll or belt used at this time, the roll surface or the belt surface in contact with the (meth)acrylic resin has a mirror surface in order to impart smoothness to the (meth)acrylic resin film surface. Is preferred.

  The protective film may contain usual additives such as an ultraviolet absorber, an organic dye, a pigment, an inorganic dye, an antioxidant, an antistatic agent and a surfactant. Of these, ultraviolet absorbers are often used to improve weather resistance.

A layer made of a cured product of the curable resin composition may be provided on the surface of the polarizer opposite to the surface on which the first protective film is attached. The curable resin composition is not particularly limited, but examples thereof include solvent-soluble, water-soluble, water-dispersed, solventless resin compositions. Moreover, as a curing method of the curable resin composition, a thermosetting type or an activation energy ray curing type can be mentioned. When it has a layer formed of a cured product of the curable resin composition, it is possible to more effectively suppress polarizer cracking in an environment in which high temperature and low temperature are repeated.
In one aspect, the polarizing plate of the present invention may have a layer made of a cured product of the curable resin composition between the polarizer and the first pressure-sensitive adhesive layer.

  The thickness of the layer formed of the cured product of the curable resin composition is preferably 0.1 μm to 10 μm or less, and more preferably 0.5 μm to 5 μm.

(Adhesive layer)
As a pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer, a conventionally known pressure-sensitive adhesive may be appropriately selected, such as peeling under a high temperature environment to which the polarizing plate is exposed, a wet heat environment, or an environment in which high and low temperatures are repeated. Any adhesive may be used as long as the adhesiveness does not occur. Specific examples thereof include an acrylic pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, and the like. In terms of transparency, weather resistance, heat resistance, and processability, for example, an acrylic pressure-sensitive adhesive can be used. .

  The pressure-sensitive adhesive may include, if necessary, a tackifier, a plasticizer, a glass fiber, glass beads, a metal powder, a filler made of other inorganic powder, a pigment, a colorant, a filler, an antioxidant, an ultraviolet absorber. , Various additives such as antistatic agents, silane coupling agents, etc. may be appropriately blended.

  The pressure-sensitive adhesive layer is usually formed by applying a pressure-sensitive adhesive solution on a release sheet and drying the solution. The release sheet can be applied by, for example, a roll coating method such as reverse coating or gravure coating, a spin coating method, a screen coating method, a fountain coating method, a dipping method, or a spray method. The release sheet provided with the adhesive layer is used by a method of transferring the release sheet or the like. The thickness of the pressure-sensitive adhesive layer is usually about 3 to 100 μm, for example 5 to 50 μm.

For example, the storage elastic modulus at 23° C. of the adhesive layer is 0.01 MPa to 1 MPa. If the storage elastic modulus of the pressure-sensitive adhesive layer is less than 0.01 MPa, shrinkage of the polarizing plate during the high temperature test cannot be suppressed, and defective appearance such as peeling tends to occur. When the storage elastic modulus of the pressure-sensitive adhesive layer is more than 1 MPa, the pressure-sensitive adhesive cannot relax the strain generated between the glass and the polarizing plate during the thermal shock test, and the polarizing plate tends to be cracked.
In one embodiment, the adhesive layer has a storage elastic modulus at 80° C. of 0.01 MPa to 1 MPa.

  A liquid crystal panel in which the polarizing plate of the present invention is bonded to a liquid crystal cell via the first pressure-sensitive adhesive layer can be obtained. Moreover, an organic electroluminescent display device can be obtained by laminating the polarizing plate on the organic electroluminescent display via the first adhesive layer. The polarizing plate of the present invention is preferably attached to the viewing side of the liquid crystal cell.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples,% and parts indicating the content or the amount used are based on mass unless otherwise specified.

[Production of polarizer]
A polyvinyl alcohol film having a thickness of 20 μm (average degree of polymerization: about 2,400, saponification degree: 99.9 mol% or more) was uniaxially stretched by a dry stretch ratio of about 5 times, and at 60° C. while maintaining a tension state After immersing in pure water for 1 minute, it was immersed in an aqueous solution having a mass ratio of iodine/potassium iodide/water of 0.05/5/100 at 28° C. for 60 seconds. Then, it was immersed in an aqueous solution having a mass ratio of potassium iodide/boric acid/water of 8.5/8.5/100 at 72° C. for 300 seconds. Subsequently, it was washed with pure water at 26° C. for 20 seconds and then dried at 65° C. to obtain a polarizer having a thickness of 7 μm and having iodine adsorbed and oriented on the polyvinyl alcohol film.

[First adhesive layer]
A commercially available pressure-sensitive adhesive sheet was used in which a 20 μm-thick acrylic pressure-sensitive adhesive layer was laminated on the release-treated surface of a polyethylene terephthalate film (release film) having a thickness of 38 μm that had been subjected to a release treatment. Urethane acrylate oligomer is not mixed in the acrylic adhesive. The storage elastic modulus of the pressure-sensitive adhesive layer obtained by removing the release film from the pressure-sensitive adhesive sheet was 0.05 MPa at 23°C and 0.04 MPa at 80°C.

[First protective film-1]
A triacetyl cellulose film (thickness 20 μm) manufactured by Konica Minolta Co., Ltd. was prepared.

[First protective film-2]
A triacetyl cellulose film (made by Toppan TOMOEGAWA Optical Film, 25KCHC-TC, thickness 32 μm) having a hard coat layer (thickness 7 μm) on the surface was prepared.

[First protective film-3]
A cycloolefin resin film (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 13 μm was prepared.

[First protective film-4]
A cycloolefin resin film (Zeon Corporation, Japan) having a thickness of 23 μm was prepared.

(Measurement of dimensional change rate)
The dimensional change rate (85° C.) in the MD direction of the protective film was measured according to the following formula.
MD direction dimensional change rate of protective film (85° C.)=[(L0-L85)/L0]×100
[In the formula, L0 means the film size of the cut film in the direction parallel to the absorption axis direction of the polarizer (MD direction, long direction of the protective film),
L85 means the film size in the direction parallel to the absorption axis direction of the polarizer (MD direction, longitudinal direction of the protective film) after 1 hour under the condition of 85° C. and 5% relative humidity. ]

In addition, the MD dimensional change rate (30° C.) of the protective film was measured according to the following formula.
MD dimensional change rate (30° C.)=[(L0 ₃₀ −L30)/L0]×100
[In the formula, L0 ₃₀ means the film size after measuring the dimensional change rate (85° C.) in the direction parallel to the absorption axis direction of the polarizer (MD direction, long direction of the protective film),
L30 means the film size in the direction parallel to the absorption axis direction of the polarizer (MD direction, longitudinal direction of the protective film) after 0.5 hours under the condition of 30° C. and 95% relative humidity. ]
Further, after measuring the dimensional change rate (85 ° C.), the temperature 23 ° C., after standing for 15 minutes at humidity of 55% was measured _{L0 30.}

  Similarly, the TD dimensional change rate (85° C.) of the protective film was measured. In Examples and Comparative Examples, the dimensional change rate (85° C.) in the width direction of the protective film (direction parallel to the transmission axis direction of the polarizer) was measured. Similarly, the TD dimensional change rate (30° C.) of the protective film was measured.

  Table 1 shows the results of the dimensional change rates obtained for the protective films 1 to 4.

[Preparation of water-based adhesive]
In 100 parts of water, 3 parts of a carboxyl group-modified polyvinyl alcohol (KL-318 manufactured by Kuraray Co., Ltd.) was dissolved, and in its aqueous solution, a polyamide epoxy-based additive that was a water-soluble epoxy compound (manufactured by Sumika Chemtex Co., Ltd.) 1.5 parts of Sumirez Resin (registered trademark) 650 (30), an aqueous solution having a solid content of 30%) was added to prepare an aqueous adhesive.

[Production of Polarizing Plate A]
The first protective film-1 was laminated on one surface of the above-mentioned polarizer via an aqueous adhesive. After the lamination, the first protective film and the polarizer were attached by drying at 80° C. for 5 minutes. A first pressure-sensitive adhesive layer laminated on a release film is laminated on the surface of the polarizer opposite to the surface laminated with the first protective film, and the first protective film, the polarizer, and the first pressure-sensitive adhesive layer. A polarizing plate A-1 was manufactured by laminating in this order.
In addition, it stuck so that the transmission axis direction of a polarizer and the width direction (TD direction) of a protective film might become parallel.

Similarly, a polarizing plate prepared by using the first protective film-2 instead of the first protective film-1 was used as a polarizing plate A-2.
Further, a polarizing plate prepared by using the first protective film-3 instead of the first protective film-1 will be referred to as a polarizing plate A-3, and a polarizing plate prepared by using the first protective film-4 will be a polarizing plate A-. It was set to 4.

The produced polarizing plate was cut into 100 mm×60 mm. The release film on the first pressure-sensitive adhesive layer was peeled off, and the polarizing plate was attached to non-alkali glass (EAGLE XG (registered trademark) manufactured by Corning Incorporated) via the first pressure-sensitive adhesive layer. A 5N load was applied to the surface of the polarizing plate by a scratch-type hardness meter (Model 318 ball diameter 0.75 mm, manufactured by Erichsen, Germany) at a location 1.0 mm from the end of the polarizing plate attached to this glass. Scratched. That is, the surface of the first protective film opposite to the polarizer was pressed. The depth of the press flaws are 2~5μ m, had a diameter of 0.3 mm (the area of the wound was approximately 0.071 ^2).

Further, samples were also prepared by applying a load of 10 N and 20 N to the surface of the polarizing plate by a scratch type hardness meter at a location 1.0 mm from the end of another polarizing plate attached to glass. The depth of the scratches produced by applying a load of 10 N was 5 to 8 μm, and the diameter was 0.4 mm (the scratch area was about 0.13 mm ² ). The depth of the scratches produced by applying a load of 20 N was 11 to 15 μm and the diameter was 0.6 mm (the scratch area was about 0.28 mm ² ).

  A cold thermal shock environment test (250 cycles) at a temperature of 85° C. and −40° C. (1 cycle for each 30 minutes) was carried out on a polarizing plate having a surface with a scratch applied by applying a load of 5 N, 10 N or 20 N.

[Cold and heat shock environment test]
The thermal shock environment test uses a thermal shock tester (product name "TSA-71L-A-3" sold by ESPEC Corporation) with a polarizing plate attached to a glass plate under high temperature conditions ( A holding time of 30 minutes at 85° C. and a holding time of 30 minutes at low temperature (-40° C.) were set as one cycle. The temperature transition time was set to 1 minute, and the conditions were set such that no external air was introduced and no dew condensation was generated on the optical member at the temperature transition time of 0 minutes during the temperature transition. The test was carried out by repeating this cycle for 250 cycles. The judgment was as follows. The results are shown in Table 2.

[Judgment]
After conducting a thermal shock environment test (cycle number: 250 times), the presence or absence of light leakage was visually confirmed. When there was no change from before the test and no light leakage occurred under the crossed Nicols after the test, "○" was given, and when light leakage occurred under the crossed Nicols after the test was given as "x".

  From these results, it is found that the polarizing plate of the present invention has an excellent effect in the thermal shock environment test. That is, according to the present invention, even under an environment where high temperature and low temperature are repeated, the polarizing plate of the present invention maintains a good appearance without causing cracks in the polarizer, and the polarizing plate of the present invention The liquid crystal display device incorporated on the viewing side does not cause light leakage.

  According to the present invention, the polarizing plate of the present invention can exhibit good polarization characteristics without causing light leakage or cracking even in an environment where high temperature and low temperature are repeated. Moreover, the polarizing plate of the present invention is a thin plate and is excellent in strength and durability.

11 First adhesive layer 12 Polarizer 13 First protective film 100 Polarizing plate

Claims (4)

A polarizing plate in which a first pressure-sensitive adhesive layer, a polarizer having a thickness of 10 μm or less, and a first protective film containing a cellulosic resin are laminated,
The first protective film has a dimensional change rate of 0.06 to 0.25 after 1 hour under conditions of 85° C. and 5% relative humidity in a direction parallel to the absorption axis direction of the polarizer.
The first protective film has a scratch on at least one of a surface of the first protective film opposite to the polarizer and a surface of the first protective film on the polarizer side,
The scratches have a length of 0.3 to 0.4 mm, a width of 0.3 to 0.4 mm, and a depth of 2 to 8 μm, and a depth of 2 to 8 μm and an area of 0.071 to 0. A polarizing plate having at least one of scratches of 13 mm ² .   The polarizing plate according to claim 1, wherein the first pressure-sensitive adhesive layer, the polarizer, and the first protective film are laminated in this order.   The polarizing plate according to claim 1, wherein the first protective film has a scratch on a surface of the first protective film opposite to the polarizer. The first protective film has a dimensional change rate of −0.25 to 0.00 after 0.5 hour under conditions of 30° C. and 95% relative humidity in a direction parallel to the absorption axis direction of the polarizer. The polarizing plate according to any one of claims 1 to 3.

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