TWI763577B - Polarizing plate, liquid crystal display device and organic electroluminescence display device - Google Patents

Abstract

An object of the present invention is to provide a thin polarizing plate excellent in strength which does not occur light leakage even when exposed to high temperature and humidity conditions, and further suppresses occurrence of poor appearance such as cracking in the polarizer under an environment where high temperature and low temperature are repeated.

The polarizing plate having a polarizer, a protective film and an adhesive layer, wherein the absolute value of the difference between the dimensional change rate (85℃) of the protective film and the dimensional change rate (30℃) of the protective film is 0.02 to 0.50, with the dimensional change rate of the protective film after one hour under the condition of 85℃ and 5% relative humidity in the direction parallel to the transmission axis direction of the polarizer being defined as the dimensional change rate (85℃) of the protective film, and the dimensional change rate of the protective film after 0.5 hours under conditions of 30℃ and 95% relative humidity in the direction parallel to the transmission axis direction of the polarizer being defined as the dimensional change rate (30 ℃) of the protective film.

Description

Polarizing plate, liquid crystal display device and organic electroluminescent display device

The present invention relates to a polarizing plate that can be used for various optical applications. Furthermore, the present invention relates to a liquid crystal display device and an organic electroluminescence display device provided with the polarizing plate.

Polarizing plates are widely used as polarized light supply elements in display devices such as liquid crystal display devices, and as polarized light sensing elements. For such a polarizing plate, a polarizer obtained by stretching and dyeing a polyvinyl alcohol film is suitable.

In Patent Document 1 (Japanese Patent Laid-Open No. 2012-145645 ), a polarizing plate is disclosed, in which the smaller the linear expansion of the protective film is than the linear expansion in the transmission axis direction of the polarizer, the greater the cracking (cracking) of the polarizer. few. According to Patent Document 1, the cracking (cracking) of the polarizing plate is evaluated by repeating the test (thermal shock acceleration test) in which the polarizing plate is simply raised and lowered between -40°C and 85°C. As described above, the evaluation of linear expansion described in Patent Document 1 is generally a temperature-dependent parameter.

Moreover, in recent years, thin polarizers have been demanded, and polarizers are also required to be thinned.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2012-145645

However, polarizers produced by stretching have a problem that cracks (cracks) easily occur along the extension axis. For example, if the polarizer is exposed to an environment with severe temperature changes, the polarizer will crack. , and optical defects such as appearance defects and light leakage occur. With the thinning of polarizers in recent years, cracks in polarizers have become more likely to occur, and a solution has been sought.

Furthermore, polarizers containing polyvinyl alcohol are limited in their use under high humidity conditions due to their low resistance to humidity.

For example, in the invention described in Patent Document 1, evaluation is performed based on linear expansion. However, an evaluation method based on linear expansion is generally expressed as a temperature-dependent parameter, and therefore, in Citation 1, the relationship between cracking (cracking) of the polarizer and humidity is not considered.

Furthermore, in order to satisfy the requirement of thinning the polarizing plate, when the polarizing plate is thinned, for example, when scratches occur on the surface of the protective film, the thin-film polarizing plate is also broken.

An object of the present invention is to provide a polarizing plate that does not leak light even when exposed to high temperature and high humidity conditions. Furthermore, the object of the present invention is to Provides a polarizing plate that suppresses appearance defects such as cracking of polarizers in an environment where high and low temperatures are repeated.

The present invention includes the following.

[1] A polarizer comprising a polarizer, a protective film, and an adhesive layer; wherein, when the protective film is parallel to the transmission axis direction of the polarizer under conditions of 85° C. relative humidity of 5% The dimensional change rate after 1 hour is set as the dimensional change rate (85°C) of the protective film, and the direction parallel to the transmission axis direction of the polarizer of the protective film is 95% relative humidity at 30°C. When the dimensional change rate after 0.5 hours has passed under the same conditions as the dimensional change rate of the protective film (30℃)

The absolute value of the difference between the dimensional change rate (85° C.) of the aforementioned protective film and the dimensional change rate (30° C.) of the aforementioned protective film is 0.02 to 0.50.

[2] The polarizing plate according to [1], wherein the dimensional change rate of the polarizer after 1 hour has passed under the conditions of 85° C. relative humidity of 5% in the transmission axis direction of the polarizer is defined as the dimensional change of the polarizer rate (85℃),

The dimensional change rate of the above-mentioned polarizer in the transmission axis direction under the condition of 95% relative humidity at 30°C for 0.5 hours is set as the dimensional change rate of the polarizer (30°C),

The absolute value of the difference between the dimensional change rate (85°C) of the polarizer and the dimensional change rate (30°C) of the polarizer is set as F _PZ ,

The absolute value of the difference between the dimensional change rate (85°C) of the protective film and the dimensional change rate (30°C) of the protective film is set as F _PF ,

The difference between the aforementioned F _PZ minus the aforementioned F _PF is set as ΔF _TD , and

The ratio of ΔF _TD to F _PZ (ΔF _TD /F _PZ ) is in the range of 0.5 to 0.95.

[3] The polarizing plate according to [1] or [2], wherein the polarizer, the protective film, and the adhesive layer are arranged in this order.

[4] The polarizing plate according to [1] or [2], wherein the protective film, the polarizer, and the adhesive layer are arranged in this order.

[5] The polarizing plate according to any one of [1] to [4], wherein the protective film is made of cellulose ester-based resin, polyester-based resin, polycarbonate-based resin, (meth)acrylic-based resin A transparent resin film composed of a resin or a mixture of at least two or more of these.

[6] A liquid crystal display device obtained by laminating the polarizing plate according to any one of the above [1] to [5] on a liquid crystal cell with the adhesive layer interposed therebetween.

[7] An organic electroluminescence display device obtained by laminating the polarizing plate according to any one of the above [1] to [5] on an organic electroluminescence display with the adhesive layer interposed therebetween.

According to the present invention, even under high temperature conditions and high humidity conditions, it is possible to suppress the occurrence of cracks and cracks in the polarizer, and to provide a polarizing plate with excellent durability. In addition, even in an environment where high temperature and low temperature are repeated, and even in an environment where dew condensation occurs, the polarizing plate of the present invention does not cause light leakage, cracking of the polarizer, and the like, and can exhibit good polarizing properties. Therefore, the polarizing plate of the present invention is suitable for use even under various conditions such as high temperature conditions and high humidity conditions, which are not conventionally applicable, without causing light leakage, cracking, and the like.

Furthermore, according to the present invention, the polarizer can be thinned, and even when scratches occur on the surface of the protective film, cracking of the polarizer can be suppressed. Therefore, the polarizing plate of the present invention is thin, and has excellent strength and durability.

11: Polarizer

12: Protective film (1st protective film)

13: Adhesive layer (1st adhesive layer)

22: The second protective film

23: Second Adhesive Layer

40: glass substrate

100, 110: polarizer

Fig. 1(a) is a schematic cross-sectional view showing an example of the layer structure of the polarizing plate of the present invention, and Fig. 1(b) is a schematic cross-sectional view showing another example of the layer structure of the polarizing plate of the present invention.

Fig. 2(a) is a schematic plan view showing the axis angle between the transmission axis and the absorption axis in a polarizing plate having a transmission axis (solid line) in the width direction, and Fig. 2(b) is a diagram showing a transmission axis in the longitudinal direction A schematic plan view of the axis angle between the transmission axis and the absorption axis in the polarizer of the transmission axis (solid line).

Fig. 3 is a schematic cross-sectional view showing an example of the layer structure of the polarizing plate of the present invention and the glass substrate to which the polarizing plate is bonded.

Hereinafter, although the polarizing plate of the present invention will be described using appropriate drawings, the present invention is not limited to these embodiments.

FIG. 1 is a schematic cross-sectional view showing an example of a preferable layer structure of the polarizing plate of the present invention. In FIG. 1( a ), the polarizing plate 100 is formed by laminating the polarizer 11 , the protective film 12 and the adhesive layer 13 . Similarly, in FIG. 1( b ), the polarizing plate 110 is formed by laminating the protective film 12 , the polarizer 11 and the adhesive layer 13 . In this way, in the present invention, the order of lamination of the polarizer, the protective film, and the adhesive layer is not particularly limited.

The polarizing plate of the present invention is a member having the function of converting light such as natural light into linearly polarized light, and the polarizing plate generally has a transmission axis and an absorption axis. The direction of the transmission axis of such a polarizer is understood as the vibration direction of the transmitted light when natural light is transmitted through the polarizer. On the other hand, the absorption axis of the polarizer is perpendicular to the transmission axis of the polarizer. Furthermore, the polarizer can generally be a stretched film, and the direction of the absorption axis of the polarizer is consistent with its extending direction.

In the present invention, the term "direction parallel to the transmission axis direction of the polarizer" means a direction parallel or slightly parallel (within an angle of ±7°) to the transmission axis direction of the polarizer. .

In the present invention, the dimensional change rate after 1 hour has elapsed under the condition of 85°C relative humidity of 5% is measured according to the following formula. In addition, the dimensional change rate after a lapse of 1 hour under the condition of 85 degreeC relative humidity of 5% is described as a dimensional change rate (85 degreeC).

For example, in the present invention, the dimensional change rate of the protective film in the direction parallel to the transmission axis direction of the polarizer under the condition of 85° C. and 5% relative humidity after 1 hour has elapsed is described as the size of the protective film Rate of change (85°C).

In addition, the dimensional change rate of the direction of the transmission axis of the polarizer under the condition of 85° C. relative humidity of 5% after 1 hour has elapsed is described as the dimensional change rate of the polarizer (85° C.).

Hereinafter, for the sake of explanation, the dimensional change rate (85° C.) of the protective film and the dimensional change rate (85° C.) of the polarizer may only be described as the dimensional change rate (85° C.).

Dimensional change rate (85℃)=[(L0-L85)/L0]×100

[In the formula, L0 represents the film size of the cut film in the direction (length direction or width direction) parallel to the transmission axis direction of the polarizer,

L85 represents the film size in the direction (length direction or width direction) parallel to the transmission axis direction of the polarizer after 1 hour at 85°C with a relative humidity of 5%. ]

For example, in the case where the dimension (L0) in the width direction of the cut film has been measured, the dimension (L85) in the width direction of the film is also measured after standing for 1 hour at 85°C under the condition of 5% relative humidity, and Calculate the dimensional change rate. In addition, after manufacturing the polarizing plate, when the dimension (L0) in the direction parallel to the transmission axis direction of the polarizing plate of the protective film obtained by removing the polarizing plate and the like from the polarizing plate has been measured, the relative humidity at 85°C is measured. After standing for 1 hour under the conditions of 5%, the dimension (L85) in the direction parallel to the transmission axis direction of the polarizer was also measured, and the dimensional change rate was calculated.

The dimensional change rate (85° C.) calculated in this way can be expressed as either a positive value (that is, shrinkage) or a negative value (that is, expansion). The protective film whose dimensional change rate (85°C) is a positive value is, for example, composed of the following: a polyolefin-based resin selected from chain polyolefin-based resins and cyclic polyolefin-based resins; Cellulose ester resins of acid esters and cellulose diacetate; (meth)acrylic resins selected from polymethyl methacrylate resins (PMMA resins) and the like.

In the same manner as above, in the present invention, the calculation of the dimensional change rate after 0.5 hours has passed under the condition of 30°C relative humidity of 95% is based on the following formula for the film after the dimensional change rate (85°C) has been measured. to measure. In addition, after 0.5 hours at 30°C and 95% relative humidity The dimensional change rate after time may be described as the dimensional change rate (30°C).

For example, in the present invention, the dimensional change rate of the protective film in the direction parallel to the transmission axis direction of the polarizer under the condition of 30°C and 95% relative humidity after 0.5 hours has elapsed is described as the protective film. Dimensional change rate (30°C). On the other hand, the dimensional change rate after 0.5 hours in a direction parallel to the transmission axis direction of the polarizer at 30°C and a relative humidity of 95% is described as the dimensional change rate of the polarizer (30°C )Case.

Hereinafter, for the sake of explanation, the dimensional change rate (30° C.) of the protective film and the dimensional change rate (30° C.) of the polarizer may only be described as the dimensional change rate (30° C.).

Dimensional change rate (30℃)=[(L030-L30)/L0]×100[In the formula, L030 represents the measured dimensional change in the direction (length direction or width direction) parallel to the transmission axis direction of the polarizer the size of the film after the rate (85°C),

L30 represents the size of the film in the direction (length direction or width direction) parallel to the transmission axis direction of the polarizer after 0.5 hours has passed under the condition of 30° C. relative humidity of 95%. ]

For example, after measuring the dimensional change rate (85° C.), the L030 can be measured after standing at a temperature of 23° C. and a humidity of 55% for 15 minutes.

The dimensional change rate (30° C.) calculated in this way can be expressed as either a positive value (that is, shrinkage) or a negative value (that is, expansion). The protective film whose dimensional change rate (30° C.) is a positive value is, for example, composed of the following: polyolefin-based resins such as chain polyolefin-based resins and cyclic polyolefin-based resins; polyester-based resins; For example polyethylene terephthalate.

On the other hand, the protective film whose dimensional change rate (30° C.) is a negative value (swelling) is composed of, for example, cellulose ester-based resins such as cellulose triacetate and cellulose diacetate, And (meth)acrylic resins such as polymethyl methacrylate resin (PMMA resin).

In the protective film of the present invention, as long as the absolute value of the difference between the dimensional change rate (85°C) and the dimensional change rate (30°C) is within the scope of the present invention, the sign of the dimensional change rate (85°C) and the dimensional change rate (30°C) The signs of ℃) may all be the same sign (positive, negative or zero), or may be different signs.

In the present invention, the absolute value of the difference between the dimensional change rate (85° C.) of the protective film and the dimensional change rate (30° C.) of the protective film is 0.02 to 0.50. The absolute value of the difference between the dimensional change rate (85° C.) of the protective film and the dimensional change rate (30° C.) of the protective film is preferably 0.03 to 0.30, and more preferably 0.03 to 0.20.

Since the polarizing plate of the present invention has the absolute value of the difference in the dimensional change rate in such a range, the polarizing plate of the present invention can be provided with excellent durability while suppressing cracking of the polarizing plate and suppressing light leakage under high temperature conditions and high humidity conditions. . Moreover, even in an environment where high temperature and low temperature are repeated, the polarizing plate of the present invention does not cause light leakage, cracking, etc., and can exhibit good polarizing properties.

Furthermore, the polarizer provided with the protective film having such characteristics can reduce the thickness of the polarizer and suppress the cracking of the polarizer even when scratches occur on the surface of the protective film.

In a preferred embodiment, the polarizing plate of the present invention,

The dimensional change rate of the aforementioned polarizer in the transmission axis direction under the condition of 85°C relative humidity of 5% after 1 hour is set as the dimensional change rate of the polarizer (85°C),

The dimensional change rate of the above-mentioned polarizer in the transmission axis direction under the condition of 95% relative humidity at 30°C for 0.5 hours is set as the dimensional change rate of the polarizer (30°C),

The absolute value of the difference between the dimensional change rate (85°C) of the polarizer and the dimensional change rate (30°C) of the polarizer is set as F _PZ ,

The absolute value of the difference between the dimensional change rate (85°C) of the protective film and the dimensional change rate (30°C) of the protective film is set as F _PF ,

When the difference between the aforementioned F _PZ minus the aforementioned F _PF is set as ΔF _TD ,

It is represented by △F _TD =F _PZ -F _PF ,

The calculation method of the dimensional change rate can be calculated based on the above.

The ratio of ΔF _TD to F _PZ (ΔF _TD /F _PZ ) is preferably in the range of 0.5 to 0.95. More preferably, ΔF _TD /F _PZ is 0.55 to 0.95, still more preferably 0.60 to 0.95.

When ΔF _TD /F _PZ exceeds 0.95, the shrinkage and/or expansion of the protective film is smaller than that of the polyvinyl alcohol film, and polymerization may occur due to the deformation between the polyvinyl alcohol film and the protective film. Rupture of vinyl alcohol film.

Since the polarizer and the protective film have such a relationship, a polarizer with excellent durability can be provided without light leakage and cracking under high temperature conditions and high humidity conditions. Moreover, even in an environment where high temperature and low temperature are repeated, the polarizing plate of the present invention does not cause light leakage, cracking, etc., and can exhibit good polarizing properties. Furthermore, the partiality of a protective film having such characteristics The polarizer can be thinned, and the cracking of the polarizer can be suppressed even when the surface of the protective film is scratched.

In a preferred embodiment, the polarizing plate of the present invention is a polarizing plate formed by a polarizer, a protective film and an adhesive layer arranged in this order. In other preferred embodiments, the polarizing plate of the present invention is a polarizing plate formed by a protective film, a polarizer and an adhesive layer arranged in this order. In a preferred embodiment, the polarizer of the present invention and the protective film are bonded together via an adhesive layer. The thickness of the adhesive layer is, for example, 0.01 μm to 5 μm. The adhesive layer can be used by those skilled in the art.

For example, the polarizing plate of the present invention may have an absorption axis and a transmission axis of the polarizer as shown in FIG. 2 .

For example, FIG. 2(a) shows a schematic diagram of the axial angle between the transmission axis 11a and the absorption axis 11b in the polarizer 100 having the transmission axis 11a of the polarizer in the width direction and the absorption axis 11b of the polarizer in the longitudinal direction floor plan. Fig. 2(b) is a schematic plan view showing the axial angle between the transmission axis 11a and the absorption axis 11b in the polarizer 100 having the transmission axis 11a of the polarizer in the longitudinal direction and the absorption axis 11b of the polarizer in the width direction .

In a preferred embodiment, as shown in FIG. 2( a ), the external shape of the polarizing plate 100 can be, for example, a rectangle with long sides and short sides. In this case, the transmission axis 11 a of the polarizer 100 (polarizer 11 ) and the short side of the polarizer 100 may be parallel or slightly parallel (the angle formed is within ±7 degrees). On the other hand, the absorption axis 11b is perpendicular to the penetration axis 11a.

Moreover, in other preferred embodiments, as shown in FIG. 2(b), the transmission axis 11a of the polarizer 100 (polarizer 11 ) and the polarizer The long sides of 100 can be parallel or slightly parallel (the angle formed is within ±7 degrees). On the other hand, the absorption axis 11b is perpendicular to the penetration axis 11a.

[Polarizer]

The polarizer may be formed by adsorbing and aligning a dichroic dye to a polyvinyl alcohol-based resin layer extending uniaxially. Generally, when the thickness of the polarizer is 20 μm or less, the thinning of the polarizer can be achieved. In the present invention, for example, a polarizer having a thickness of 10 μm or less can be used, and preferably a polarizer having a thickness of 8 μm or less. Also, the polarizer of the present invention usually has a thickness of 2 μm or more.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, for example, a copolymer of vinyl acetate and other monomers that can be copolymerized therewith may be exemplified. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamides having an ammonium group, and the like.

The degree of saponification of the polyvinyl alcohol-based resin may be in the range of 80 mol % or more, preferably 90 mol % or more, and more preferably 95 mol % or more. The polyvinyl alcohol-based resin may be a partially modified modified polyvinyl alcohol, for example, polyvinyl alcohol modified by the following: olefins such as ethylene and propylene; acrylic acid, methacrylic acid, and crotonic acid, etc. Saturated carboxylic acids; alkyl esters of unsaturated carboxylic acids and acrylamides, etc. The average degree of polymerization of the polyvinyl alcohol-based resin is preferably from 100 to 10,000, more preferably from 1,500 to 8,000, and even more preferably from 2,000 to 5,000.

Polarizers, for example, can be made of polyvinyl alcohol-based trees The raw material film composed of grease is uniaxially stretched, dyed with a dichroic dye (dyeing treatment), then treated with an aqueous boric acid solution (boric acid treatment), washed with water (water washing treatment), and finally dried to produce.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before the dyeing of the dichroic dye, simultaneously with the dyeing of the dichroic dye, or after the dyeing of the dichroic dye. When the uniaxial stretching is performed after the dyeing of the dichroic dye, the uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. Of course, one-axis extension can also be performed in these multiple stages. To implement one-axis extension, the extension can be performed between rollers with different rotational speeds, or the extension can be performed by clamping with hot rollers. In addition, it may be dry stretching in which stretching is performed in the atmosphere, or wet stretching in which stretching is performed in a state of being swollen by 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-based resin film is dyed with a dichroic dye, and the dichroic dye is adsorbed to the film. The dyeing treatment may be performed by, for example, immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. Specifically, a dichroic dye system uses iodine or a dichroic dye.

When iodine is used as a dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film by immersing it in an aqueous solution containing iodine and potassium iodide is generally employed. The content of iodine in the aqueous solution is usually about 0.01 to 0.5 parts by weight relative to 100 parts by weight of water; the content of potassium iodide is usually about 0.5 to 10 parts by weight relative to 100 parts by weight of water. The temperature of the aqueous solution is usually about 20 to 40°C, and the immersion time in the 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 dyeing a polyvinyl alcohol-based resin film by immersing it in an aqueous solution containing a water-soluble dichroic dye is generally employed. The content of the dichroic dye in the aqueous solution is usually about 1×10 ^-3 to 1×10 ^-2 parts by weight with respect to 100 parts by weight of water. The aqueous solution may also contain inorganic salts such as sodium sulfate. The temperature of the aqueous solution is usually about 20 to 80°C, and the immersion time in the 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 a boric acid aqueous solution. The content of boric acid in the boric acid aqueous solution is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight, relative to 100 parts by weight of water. When iodine is used as a dichroic dye, it is preferable that the boric acid aqueous solution contains potassium iodide. The content of potassium iodide in the boric acid aqueous solution is usually about 2 to 20 parts by weight, preferably 5 to 15 parts by weight, relative to 100 parts by weight of water. The immersion time in the boric acid aqueous solution is usually about 100 to 1200 seconds, preferably 150 seconds or more, more preferably 200 seconds or more, and preferably 600 seconds or less, more preferably 400 seconds or less. The temperature of the boric acid aqueous solution is usually 50°C or higher, preferably 50 to 85°C. In the boric acid aqueous solution, sulfuric acid, hydrochloric acid, acetic acid, ascorbic acid, etc. can be added as a pH adjuster.

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

[protective film]

As described above, the protective film of the present invention is one where the absolute value of the difference between the dimensional change rate (85°C) of the protective film and the dimensional change rate (30°C) of the protective film is 0.02 to 0.50.

The protective film is laminated on at least one side of the polarizer. Furthermore, a protective film (1st protective film) may be layered on one area of the polarizer, and another protective film (2nd protective film) may be layered on the other area. It is preferably a single-area layer protective film (first protective film) for a polarizer. The first protective film and the second protective film may be a single layer, or a plurality of films may be laminated with an adhesive or an adhesive.

The protective film (the first protective film) and the second protective film may each be a transparent resin film made of a thermoplastic resin. Examples of thermoplastic resins include polyolefin-based resins such as chain polyolefin-based resins and cyclic polyolefin-based resins such as polypropylene-based resins; cellulose such as cellulose triacetate and cellulose diacetate Ester resin; polyester resin such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; polycarbonate resin; selected from polymethyl methacrylate resin (meth)acrylic resin; or a mixture of at least two or more of these. Furthermore, a copolymer of at least two or more monomers constituting the above-mentioned resin may also be used.

Cyclic polyolefin-based resins are generally a general term for resins polymerized with cyclic olefins as polymerized units, for example, Japanese Patent Application Laid-Open Resins described in Japanese Patent Laid-Open No. 1-240517, Japanese Patent Laid-Open No. 3-14882, Japanese Patent Laid-Open No. 3-122137, and the like. Specific examples of cyclic polyolefin-based resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, and those composed of chain olefins such as ethylene and propylene and cyclic olefins. Copolymers (representative examples are random copolymers), graft copolymers modified with unsaturated carboxylic acids or derivatives thereof, and hydrogenated products thereof. Among them, norbornene-based resins using norbornene-based monomers such as norbornene or polycyclic norbornene-based monomers as cyclic olefins are suitable.

Cyclic polyolefin-based resins are sold in various commercial products. Examples of commercially available cyclic polyolefin-based resins include "TOPAS" (registered trademark) manufactured by TOPAS ADVANCED POLYMERS GmbH and sold by Polyplastics Co., Ltd. in Japan, and JSR Co., Ltd. "ARTON" (registered trademark) sold by Japan ZEON Co., Ltd., "ZEONOR" (registered trademark) and "ZEONEX" (registered trademark), sold by Mitsui Chemicals Co., Ltd. "APEL" (registered trademark), etc. .

Furthermore, a film-formed cyclic polyolefin-based resin film can be used as a protective film. Examples of commercially available products include "ARTON FILM" sold by JSR Co., Ltd. ("ARTON" is a registered trademark of the company), and "ESCENA" (registered trademark) sold by Sekisui Chemical Industry Co., Ltd. trademark) and "SCA40", "ZEONOR FILM" (registered trademark) sold by ZEON Co., Ltd., Japan, etc.

Cellulose ester resins are usually esters of cellulose and fatty acids. Specific examples of cellulose ester-based resins include cellulose triacetic acid Esters, cellulose diacetate, cellulose tripropionate, cellulose dipropionate, etc. In addition, these copolymers, or a part of the hydroxyl group modified with other substituents can be used. Among these, cellulose triacetate (triacetoxycellulose: TAC) is particularly preferred. There are many products of cellulose triacetate on the market, and they are advantageous from the viewpoints of availability and cost. Examples of commercially available products of cellulose triacetate are represented by trade names, such as "Fujitac (registered trademark) TD80", "Fujitac (registered trademark) TD80UF", "Fujitac (registered trademark) TD80UF" sold by Fujifilm Co., Ltd. ) TD80UZ" and "Fujitac (registered trademark) TD40UZ", TAC films "KC8UX2M", "KC2UA" and "KC4UY" manufactured by Konica Minolta Co., Ltd., and the like.

Polymethacrylates and polyacrylates (hereafter, polymethacrylates and polyacrylates may be collectively referred to as (meth)acrylic resins) are readily available on the market.

The (meth)acrylic resin type includes, for example, a homopolymer of an alkyl methacrylate or an alkyl acrylate, or a copolymer of an alkyl methacrylate and an alkyl acrylate. Specific examples of alkyl methacrylates include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and the like; and specific examples of alkyl acrylates include methyl acrylate. , ethyl acrylate, propyl acrylate, etc. And as such a (meth)acrylic-type resin, a commercially available general-purpose (meth)acrylic-type resin can be used, and what is called an impact-resistant (meth)acrylic-type resin can also be used for a (meth)acrylic-type resin.

(Meth)acrylic resins are generally polymers mainly composed of methacrylates. Methacrylate, can be 1 methacrylate The ester homopolymer may be a copolymer of methacrylate and other methacrylates or acrylates. Examples of methacrylates include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate, and the number of carbon atoms in the alkyl group is usually about 1 to 4. Furthermore, cycloalkyl methacrylates such as cyclopentyl methacrylate and cyclohexyl methacrylate; aryl methacrylates such as phenyl methacrylate; methyl methacrylates such as cyclohexylmethyl methacrylate can also be used Cycloalkyl acrylate; aralkyl methacrylate such as benzyl methacrylate.

The said other polymerizable monomer which can comprise a (meth)acrylic-type resin is mentioned, for example, an acrylate, a methacrylate, and a polymerizable monomer other than an acrylate. As the acrylate system, alkyl acrylate can be used, and specific examples thereof include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, and 2-butyl acrylate. - Alkyl acrylate having 1 to 8 carbon atoms in the alkyl group such as ethylhexyl, cyclohexyl acrylate, and 2-hydroxyethyl acrylate. The carbon number of the alkyl group is preferably 1 to 4. Among the (meth)acrylic resins, the acrylate may be used alone or in combination of two or more.

The polymerizable monomers other than methacrylates and acrylates include, for example, monofunctional monomers having one polymerizable carbon-carbon double bond in the molecule, or at least two polymerizable carbon-carbon double bonds in the molecule. multifunctional monomers, and it is better to use monofunctional monomers. 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, maleic anhydride, Unsaturated acids such as methylene succinic anhydride; N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide and other maleic butenes Diimide; allyl alcohols such as methacryl alcohol and allyl alcohol; vinyl acetate, ethylene chloride, ethylene, propylene, 4-methyl-1-pentene, 2- Hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, N-vinyl carbazole and other monomers.

Further, specific examples of the polyfunctional monomer include polyunsaturated carboxylic acids of polyhydric alcohols such as ethylene glycol dimethacrylate, butanediol dimethacrylate, and trimethylolpropane trimethacrylate. Ester; allyl acrylate, allyl methacrylate, allyl cinnamate and other allyl unsaturated carboxylic acid; diallyl phthalate, diallyl maleate, melamine Aromatic polyalkenyl compounds such as polyvinyl esters of polybasic acids such as triallyl acid and triallyl triisocyanate, and divinyl benzene. Polymerizable monomers other than methacrylates and acrylates may be used alone or in combination of two or more.

The composition of the preferred monomers of the (meth)acrylic resin is based on the total monomer amount, and the alkyl methacrylate is 50 to 100% by weight, the alkyl acrylate is 0 to 50% by weight, and other than these The polymerizable monomer is 0 to 50% by weight; more preferably, the alkyl methacrylate is 50 to 99.9% by weight, the alkyl acrylate is 0.1 to 50% by weight, and the polymerizable monomers other than these are 0 to 49.9% by weight %By.

Moreover, since the (meth)acrylic resin can improve the durability of the film, it can have a ring structure in the polymer main chain. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure, and a lactone ring structure. make. Specifically, for example, cyclic acid anhydride structures such as glutaric anhydride structures and succinic anhydrides; cyclic imide structures such as glutarimide structures and succinimide structures; Ester ring structure. The higher the content of the ring structure in the main chain, the higher the glass transition temperature of the (meth)acrylic resin can be. Cyclic acid anhydride structure and cyclic imide structure can be introduced by copolymerizing monomers having a cyclic structure such as maleic acid or maleimide, and dehydration after polymerization - The method of introducing a cyclic acid anhydride structure by a demethanol condensation reaction, a method of introducing a cyclic imide structure by reacting an amine compound, and the like. Resins (polymers) with a lactone ring structure can be prepared by preparing a polymer with hydroxyl groups and ester groups in the polymer chain, and then the hydroxyl groups and ester groups of the obtained polymer can be mixed with catalysts such as organophosphorus compounds as required. It is obtained by a method of forming a lactone ring structure by cyclization and condensation by heating.

For polymers having hydroxyl groups and ester groups in the polymer chain, for example, methyl 2-(hydroxymeth)acrylate, ethyl 2-(hydroxymeth)acrylate, isopropyl 2-(hydroxymeth)acrylate can be used. Esters, n-butyl 2-(hydroxymeth)acrylate, 3-butyl 2-(hydroxymeth)acrylate, etc. are obtained as a part of monomers, and (meth)acrylate which has a hydroxyl group and an ester group. A more specific preparation method of a polymer having a lactone ring structure is described in, for example, Japanese Patent Laid-Open No. 2007-254726.

A (meth)acrylic resin can be prepared by radically polymerizing the monomer composition containing the above-mentioned monomers. The monomer composition system may contain a solvent or a polymerization initiator as required.

(meth)acrylic resin may contain the above-mentioned (methyl) Resins other than acrylic resins. The content ratio of the other resin is preferably 0 to 70% by weight, more preferably 0 to 50% by weight, and still more preferably 0 to 30% by weight. The resin can be, for example, olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, and poly(4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and vinyl chloride resin ; Styrenic polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer; polyethylene terephthalate, polybutylene terephthalate, polynaphthalene Polyester such as ethylene dicarboxylate; polyarylate composed of aromatic diol and aromatic dicarboxylic acid; biodegradable polyester such as polylactic acid and polybutylene succinate; polycarbonate; nylon 6 , nylon 66, nylon 610 and other polyamides; polyacetal; polyphenylene ether; polyphenylene sulfide; polyether ether ketone; polyether nitrile; Amide imide, etc.

The (meth)acrylic resin may contain rubber particles from the viewpoint of improving the impact resistance and film formability of the film. The rubber particles may be particles composed of only a layer exhibiting rubber elasticity, or may be particles having a multilayer structure including a layer exhibiting rubber elasticity and other layers. The rubber elastic system includes, for example, an olefin-based elastic polymer, a diene-based elastic polymer, a styrene-diene-based elastic polymer, an acrylic-based elastic polymer, and the like. Among them, it is preferable to use an acrylic elastic polymer from the viewpoint of light resistance and transparency.

The acrylic elastic polymer is mainly composed of an alkyl acrylate, that is, a polymer containing 50% by weight or more of structural units derived from an alkyl acrylate based on the total amount of monomers. Acrylic elastic polymer, which may be a homopolymer of alkyl acrylate, or may contain 50% by weight or more A copolymer of the constituent unit derived from the alkyl acrylate above and the constituent unit derived from other polymerizable monomers in an amount of 50 wt % or less.

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-mentioned other polymerizable monomers include: alkyl methacrylates such as methyl methacrylate and ethyl methacrylate; styrene-based monomers such as styrene and alkyl styrene; acrylonitrile , Monofunctional monomers such as unsaturated nitrile such as methacrylonitrile; in addition, allyl (meth)acrylate, ethylenic ester of unsaturated carboxylic acid such as methacrylate (meth)acrylate; maleic Diene esters of dibasic acids such as diallyl acid; polyfunctional monomers such as unsaturated carboxylic acid diesters of diols such as alkanediol di(meth)acrylates.

The rubber particles containing the acrylic elastic polymer are preferably particles having a multilayer structure of layers of the acrylic elastic polymer. Specifically, for example, a two-layer structure having a hard polymer layer mainly composed of alkyl methacrylate on the outer side of the layer of the acrylic elastic polymer, or the inner side of the layer of the acrylic elastic polymer can be mentioned. A three-layer structure with a rigid polymer layer mainly composed of alkyl methacrylate.

An example of the monomer composition of the polymer mainly composed of alkyl methacrylate constituting the "hard polymer layer formed on the outer or inner side of the layer of the acrylic elastic polymer" is the same as that of the (meth)acrylic polymer. The examples of the monomer composition of the polymer mainly composed of alkyl methacrylate are the same as the examples of the resin, and the monomer composition system mainly composed of methyl methacrylate is suitable. The acrylic rubber elastomer particles of such a multilayer structure can be obtained, for example, by the method described in Japanese Patent Publication No. Sho 55-27576. method of manufacture.

From the viewpoints of the film formability of the (meth)acrylic resin, the impact resistance of the film, and the smoothness of the film surface, the rubber particles are preferably attached to the rubber elastomer layer (layer of the acrylic elastic polymer) contained therein. ) to have an average particle diameter in the range of 10 to 350 nm. The average particle diameter is more preferably 30 nm or more, still more preferably 50 nm or more, more preferably 300 nm or less, and still more preferably 280 nm or less.

The average particle diameter of the rubber particles to the rubber elastic body layer (layer of the acrylic elastic polymer) is measured in the following manner. That is, when such rubber particles are mixed with a (meth)acrylic resin to form a thin film, and the cross section is dyed with an aqueous solution of ruthenium oxide, only the rubber elastic body layer is colored, and a slightly circular shape is observed, but the parent layer has a The methacrylic resin was not dyed. Then, from the cross section of the membrane dyed in this way, thin sections are prepared using a microtome or the like, and observed with an electron microscope. Next, 100 dyed rubber particles were randomly selected, and the particle diameter (diameter up to the rubber elastic body layer) of each particle was calculated, and the average value of the number was used as the above-mentioned average particle diameter. Since it is measured by such a method, the said average particle diameter obtained is a number average particle diameter.

When the rubber particles are rubber particles in which the outermost layer is a hard polymer mainly composed of methyl methacrylate and a rubber elastomer layer (layer of acrylic elastic polymer) is wrapped therein, if it is mixed with the methyl methacrylate of the parent For the acrylic resin, the outermost layer of the rubber particles is mixed with the parent methacrylic resin. Therefore, when the cross section was dyed with an aqueous solution of ruthenium oxide and observed with an electron microscope, the rubber particles were observed to be particles in a state in which the outermost layer was removed. Specifically, when the rubber particles are the inner layer of acrylic When the outer layer is an elastic polymer and the outer layer is a rubber particle with a two-layer structure of a rigid polymer mainly composed of methyl methacrylate, the acrylic elastic polymer part of the inner layer is dyed, and particles with a single-layer structure are observed. Moreover, when the rubber particle is the innermost layer is a rigid polymer mainly composed of methyl methacrylate, the middle layer is an acrylic elastic polymer, and the outermost layer is a rigid polymer mainly composed of methyl methacrylate. In the case of the rubber particles of the layered structure, the particle center part of the innermost layer was not dyed, but only the acrylic elastic polymer part of the intermediate layer was dyed, and the particles of the two-layered structure were observed.

From the viewpoints of the film formability of the (meth)acrylic resin, the impact resistance of the film, and the smoothness of the film surface, the compounding ratio of the rubber particles is based on the (meth)acrylic resin film (meth)acrylic resin film. Based on the total amount of the acrylic resin, it is preferably 3% by weight or more and 60% by weight or less, more preferably 45% by weight or less, and more preferably 35% by weight or less. When the amount of the rubber elastic body particles is more than 60% by weight, the dimensional change of the film becomes large, and the heat resistance decreases. On the other hand, when the amount of the rubber elastic body particles is less than 3% by weight, the film has good heat resistance, but has poor windability and low productivity during film formation. Furthermore, in the present invention, when the rubber elastic body particles are particles having a multilayer structure having a layer exhibiting rubber elasticity and other layers, the weight of the portion constituted by the layer exhibiting rubber elasticity and the inner layer is regarded as the weight. is the weight of the rubber elastomer particle. For example, when using the acrylic rubber elastomer particles having the above-mentioned three-layer structure, the total weight of the acrylic elastic polymer portion of the intermediate layer and the rigid polymer portion mainly composed of methyl methacrylate in the innermost layer is calculated as the total weight. is the weight of the rubber elastomer particle. When dissolving the acrylic rubber elastomer particles with the above three-layer structure in acetone, Since the acrylic elastic polymer part of the middle layer and the hard polymer part mainly composed of methyl methacrylate in the innermost layer remain as insoluble components, it is possible to easily obtain the content of the acrylic rubber particles with the three-layer structure. The total weight ratio of the middle layer to the innermost layer.

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 can be obtained by combining the (meth)acrylic resin with the rubber. The particles can be obtained by mixing by melt kneading or the like, and can also be obtained by a method of first producing rubber particles and polymerizing a monomer composition serving as a raw material of a methacrylic resin in the presence of the particles.

Common additives, such as ultraviolet absorbers, organic dyes, pigments, inorganic pigments, antioxidants, antistatic agents, surfactants, etc., may also be contained in the protective film. Among them, an ultraviolet absorber is preferable because it improves the weather resistance. Examples of ultraviolet absorbers include 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2- base) phenol], 2-(5-methyl-2-hydroxyphenyl)-2H-benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl) ) phenyl]-2H-benzotriazole, 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(3-tert-butyl-5 -Methyl-2-hydroxyphenyl)-5-chloro-2H-benzotriazole, 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chloro-2H-benzo Triazole, 2-(3,5-di-tert-pentyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)-2H - Benzotriazole-based UV absorbers such as benzotriazole; Hydroxybenzophenone, 2-Hydroxy-4-methoxy-4'-chlorobenzophenone, 2,2'-Dihydroxy-4-methoxydiphenyl ketone, 2,2'-dihydroxy-4,4'-dimethoxydiphenyl ketone, etc. 2-hydroxy benzophenone UV absorbers; phenyl salicylate UV absorbers such as p-tert-butylphenyl salicylate and p-octylphenyl salicylate; 2,4-diphenyl-6-(2- Hydroxy-4-methoxyphenyl)-1,3,5-triazine (triazine), 2,4-diphenyl-6-(2-hydroxy-4-ethoxyphenyl)-1,3 ,5-triazine, 2,4-diphenyl-(2-hydroxy-4-propoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-(2-hydroxy- 4-Butoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine , 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4 -Octyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine oxazine, 2,4-diphenyl-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-[1-octyloxy] ylcarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine, 4-bis[2-hydroxy-4-butoxyphenyl]- 6-(2,4-Dibutoxyphenyl)-1,3,5-triazine, 2-[4-[2-hydroxy-3-(2'-ethyl)hexyloxy]-2- Hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(4,6-bis(2,4-dimethylphenyl) -1,3,5-Triazin-2-yl)-5-hydroxyphenyl, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine- 2-yl]-5-(octyloxy)phenol, 2-[2,6-bis(2,4-xylyl)-1,3,5-triazin-2-yl]-5-octyloxy phenol, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexyl)ethoxy]phenol, 2, Triazine-based ultraviolet absorbers such as 4,6-tris(2-hydroxy-4-hexyloxy-3-methoxyphenyl)-1,3,5-triazine, and the like. These 2 or more types can be used as needed.

Commercially available UV absorbers can be used. For example, triazine-based UV absorbers are manufactured by Chempro Chemicals Co., Ltd. "Kemisorb 102" (registered trademark), "ADEKA STAB (registered trademark) LA46" by ADEKA Co., Ltd., "ADEKA STAB (registered trademark) LAF70", "TINUVIN (registered trademark) 460" by BASF Corporation, "TINUVIN" (registered trademark) 405", "TINUVIN (registered trademark) 400" and "TINUVIN (registered trademark) 477", "CYASORB (registered trademark) UV-1164" manufactured by Sun Chemical Co., Ltd. (all of the above are trade names), etc. . Benzotriazole-based ultraviolet absorbers include, for example, "ADEKA STAB LA31" and "ADEKA STAB LA36" manufactured by ADEKA Co., Ltd., "SUMISORB (registered trademark) 200" manufactured by Sumika Chemtex Co., Ltd., "SUMISORB (registered trademark)" trademark) 250", "SUMISORB (registered trademark) 300", "SUMISORB (registered trademark) 340" and "SUMISORB (registered trademark) 350", "Kemisorb 74" (registered trademark) by CHEMPRO Chemical Co., Ltd., "Kemisorb 79" (registered trademark) and "Kemisorb 279" (registered trademark), "TINUVIN (registered trademark) 99-2", "TINUVIN (registered trademark) 900" and "TINUVIN (registered trademark) 928" (above) manufactured by BASF are all trade names), etc. When the (meth)acrylic resin film contains an ultraviolet absorber, the amount thereof is usually 0.1 wt % or more, preferably 0.3 wt % or more, relative to 100 wt % of the (meth)acrylic resin. Preferably it is 3 weight% or less.

When producing a (meth)acrylic resin film, a conventionally known film forming method can be used. The (meth)acrylic resin film may have a multilayer structure, and the (meth)acrylic resin film of the multilayer structure may adopt a method using a feed block, a method using a multi-manifold die Methods, etc., various methods of general well-known. Among them, for example, the layers are stacked through the feeding module, and the multi-layer melt extrusion molding is performed from the T-die to make the obtained layer The method of forming a film by contacting at least one side of the layered film with a roller or a belt is preferable because a film with good surface properties and shape can be obtained. In particular, from the viewpoint of improving the surface smoothness and surface glossiness of the (meth)acrylic resin film, it is preferable that both surfaces of the laminated film obtained by melt extrusion molding of the above-mentioned multilayers are brought into contact with the surface of the roller or the surface of the belt. A method of thinning. The roller or belt used at this time has a surface of the roller or belt that is in contact with the (meth)acrylic resin film, and in order to impart smoothness to the surface of the (meth)acrylic resin film, the surface is a mirror surface. better.

The (meth)acrylic resin film may be obtained by subjecting the film produced as described above to a stretching treatment. In order to obtain a film having desired optical properties and mechanical properties, stretching treatment may be necessary. The stretching treatment system includes, for example, uniaxial stretching, biaxial stretching, and the like. The extending direction system includes, for example, the mechanical flow direction (MD) of the unstretched film, a direction perpendicular thereto (TD), a direction oblique to the mechanical flow direction (MD), and the like. The biaxial extension can be simultaneous biaxial extension extending in two extending directions simultaneously, or successive biaxial extension extending in a specified direction and then extending in other directions.

The first protective film and the second protective film may be a protective film having both optical functions such as a retardation film and a brightness enhancement film, as long as they are within the scope of the present invention. For example, a retardation film can be prepared by extending a transparent resin film made of the above-mentioned materials (uniaxial stretching or biaxial stretching, etc.), or forming a liquid crystal layer on the film, etc., to give an arbitrary retardation value.

The first protective film and the second protective film can form surface treatment layers (coating layers such as hard coat layer, anti-glare layer, anti-reflection layer, anti-static layer and anti-fouling layer) on the surface opposite to the polarizer. ). on the surface of the protective film As the method of forming the surface treatment layer, a known method can be used.

The first protective film and the second protective film may be the same protective film or different protective films. Examples of the case where the protective film is different include the following combinations: a combination in which the type of thermoplastic resin constituting the protective film is at least different; the presence or absence of the optical function of the protective film or a combination in which the type is at least different; the surface treatment layer formed on the surface. The presence or absence of or a combination of at least different types, etc.

The thickness of the first protective film and the second protective film is preferably thin from the viewpoint of thinning the polarizing plate, but when too thin, the strength decreases and the workability deteriorates. Therefore, the thickness of the first protective film and the second protective film is preferably 5 to 90 μm or less, more preferably 60 μm or less, still more preferably 50 μm or less, and particularly preferably 30 μm or less.

The protective film (1st protective film) can easily obtain the effect of the present invention as long as it has an appropriate dimensional change due to water absorption. It is preferably a transparent resin film composed of a cellulose ester-based resin, a polyester-based resin, a polycarbonate-based resin, a (meth)acrylic-based resin, or a mixture of at least two or more of these, more preferably a fiber A transparent resin film composed of a plain ester resin, a (meth)acrylic resin, or a mixture of at least two or more of these.

(adhesive)

The adhesive for forming the adhesive layer may be appropriately selected from those known in the past, and the adhesive should be bonded to such an extent that peeling does not occur in a high-temperature environment to which the polarizing plate is exposed, a humid-heat environment, or an environment where high and low temperatures are repeated. Those who are sexual can do it. Specifically, for example, acrylic adhesives, silicone adhesives, rubber adhesives, etc. are mentioned. From the viewpoints of transparency, weather resistance, heat resistance, and processability, acrylic adhesives are used as the Excellent.

In the adhesive, adhesion-imparting agents, plasticizers, glass fibers, glass beads, metal powders, fillers composed of other inorganic powders, pigments, colorants, fillers, antioxidants, Various additives such as UV absorbers, antistatic agents, and silane coupling agents.

The adhesive layer is usually formed by applying an adhesive solution on a release sheet and drying it. For coating on the release sheet, for example, roll coating methods such as reverse coating and gravure coating methods, spin coating methods, screen coating methods, fountain coating methods, and dip coating methods can be used. , spray method, etc. The release sheet provided with an adhesive bond layer is used by the method of transcribe|transferring it, or the like. The thickness of the adhesive layer is usually about 3 to 100 μm, preferably 5 to 50 μm.

The storage elastic modulus of the adhesive layer at 23° C. is preferably 0.01 MPa to 1 MPa. When the storage elastic modulus of the adhesive layer is less than 0.01 MPa, the shrinkage of the polarizing plate during a high temperature test cannot be suppressed, and appearance defects such as peeling tend to occur easily. Moreover, when the storage elastic modulus of the adhesive layer is greater than 1MPa, the adhesive cannot alleviate the deformation between the glass and the polarizer during the thermal shock test, and the polarizer tends to crack.

In a preferred embodiment, the storage elastic modulus of the adhesive layer at 80° C. is 0.01 MPa to 1 MPa.

A liquid crystal panel can be obtained by bonding a polarizing plate to a liquid crystal cell via an adhesive layer. And an organic electroluminescent display device can be obtained by bonding a polarizing plate to an organic electroluminescent display via an adhesive layer. For example, a liquid crystal panel and an organic electroluminescent display, as shown in FIG. 3, may have a glass substrate 40, a first adhesive layer 13, a first protective film 12, a polarizer 11, a second adhesive layer 23, a 2. Configuration of the protective film 22.

According to the polarizing plate of the present invention, a thin polarizing plate with excellent strength can be provided.

(Example)

Hereinafter, although an Example is shown and this invention is demonstrated more concretely, this invention is not limited to these Examples. In the example, the % and part indicating the content or usage amount are based on weight unless otherwise specified.

[Manufacture of polarizers]

A polyvinyl alcohol film with a thickness of 20 μm (average degree of polymerization 2,400, average degree of saponification 99.9 mol% or more) was monoaxially stretched to about 5 times by dry stretching, and then immersed in pure water at 60°C for 1 minute while maintaining tension Then, the weight ratio of iodine/potassium iodide/water was immersed in the aqueous solution of 0.05/5/100 at 28 degreeC for 60 second. Then, it was immersed at 72 degreeC for 300 second in the aqueous solution whose weight ratio of potassium iodide/boric acid/water is 8.5/8.5/100. Then, after washing with pure water at 26° C. for 20 seconds, it was dried at 65° C. to obtain a polarizer having a thickness of 7 μm in which iodine was adsorbed and aligned on a polyvinyl alcohol film.

[1st adhesive layer]

A commercially available adhesive sheet having an acrylic pressure-sensitive adhesive layer of 20 μm in thickness on the release-treated area of a 38 μm-thick polyethylene terephthalate film (release film) subjected to release treatment was used . In the acrylic adhesive, no urethane acrylate oligomer was prepared. The storage elastic modulus of the adhesive layer after removing the release film from the adhesive sheet was 0.05 MPa at 23°C and 0.04 MPa at 80°C.

[Second adhesive layer]

An organic solvent solution obtained by adding an urethane acrylate oligomer and an isocyanate-based crosslinking agent to a copolymer of butyl acrylate and acrylic acid was applied by a knife coater to a 38-μm-thick polymer having undergone mold release treatment. The mold release process surface of the ethylene terephthalate film (release film) was dried so that the thickness after drying might be 5 micrometers, and the adhesive sheet in which the adhesive layer was laminated|stacked was obtained. The storage elastic modulus of the adhesive layer after removing the release film from the adhesive sheet was 0.40 MPa at 23°C and 0.18 MPa at 80°C.

[1st protective film-1]

A triacetate-based cellulose film (thickness 20 μm, in-plane retardation value at wavelength 590 nm=1.2 nm, thickness direction retardation value at wavelength 590 nm=1.3 nm) manufactured by Konica Minolta Co., Ltd. was used.

[1st protective film-2]

Use the brand name "KC2UA" manufactured by Konica Minolta Co., Ltd., Unextended TAC film with a thickness of 25 μm.

[1st protective film-3]

A cycloolefin resin film (manufactured by ZEON Co., Ltd.) with a thickness of 13 μm was used. In-plane retardation value at wavelength 590nm (Re(590))=0.8nm, thickness direction retardation value at wavelength 590nm (Rth(590))=3.4nm, thickness direction retardation value at wavelength 483nm (Rth( 483))=3.5nm, the retardation value in the thickness direction at a wavelength of 755nm (Rth(755))=2.8nm.

[1st Protective Film-4]

The trade name "ZEONOR FILM (registered trademark) ZF14-023" manufactured by Japan ZEON Co., Ltd., and a cyclic polyolefin-based resin film having a thickness of 23 μm was used.

[1st protective film-5]

A triacetate-based cellulose film (manufactured by Toppan TOMOEGAWA Optical Film Co., Ltd., 25KCHC-TC, thickness 32 μm) whose surface was hard-coated (thickness: 7 μm) was used.

[1st Protective Film-6]

The first protective film-1 was dissolved in 1,3-dioxolane (1,3-dioxolane) to prepare 12 wt %, and applied on a glass substrate using a bar coater (number: 60) to obtain a After drying in an oven at 60° C. for 3 minutes so that the thickness after drying might be 10 μm, the coating film was peeled off from the glass to obtain a first protective film-6.

[Second protective film]

A brightness enhancement film (manufactured by 3M, trade name Advanced Polarized Film, Version 3) with a thickness of 26 μm was used.

[Preparation of water-based adhesive]

With respect to 100 parts of water, 3 parts of carboxyl-modified polyvinyl alcohol (KL-318, manufactured by Kuraray Co., Ltd.) was dissolved, and a polyamide epoxy-based additive ( 1.5 parts of SUMIREZ RESIN (registered trademark) 650 (30), an aqueous solution with a solid content concentration of 30%, manufactured by Sumika Chemtex Co., Ltd. was prepared as a water-based adhesive.

[Production of Polarizer Precursor A]

The first protective film-1 was laminated on one side of the above-mentioned polarizer with an aqueous adhesive interposed therebetween. After lamination, the 1st protective film-1 and the polarizer were bonded together by drying at 80 degreeC for 5 minutes. The 2nd adhesive bond layer laminated|stacked on the mold release film is bonded to the surface on the opposite side to the bonding surface of the polarizer and the 1st protective film-1. The 1st adhesive bond layer laminated|stacked on the mold release film is bonded to the surface on the opposite side of the bonding surface with the polarizer of 1st protective film-1.

Furthermore, it is bonded so that the transmission axis direction of a polarizer and the width direction of a protective film may become parallel.

Thus, the polarizing plate precursor A-1 in which the 1st adhesive bond layer, the protective film, the polarizer, and the 2nd adhesive bond layer were laminated|stacked in this order was produced.

Similarly, the first protective film-2 was used instead of the first protective film-1, and the polarizing plate precursor was prepared as the polarizing plate precursor A-2. A polarizing plate precursor was similarly prepared for other protective films.

[Production of polarizing plate A]

The release film on the 2nd adhesive bond layer of the said polarizing plate precursor was peeled. The second adhesive layer of the polarizing plate precursor A is bonded to the brightness enhancement film to obtain the first adhesive layer, the protective film (the first protective film), the polarizer, the second adhesive layer, and the brightness enhancement film (the first protective film). 2 protective film) The polarizing plate A laminated|stacked in this order. For example, the polarizing plate produced using the first protective film-1 is polarizing plate A1. Similarly, the polarizing plate with such a structure made using the 1st protective film-2 is polarizing plate A2.

[Production of polarizing plate B]

A polarizing plate B1 was produced in the same manner as the polarizing plate A1 described above, except that the positions of the polarizers and the protective films in the polarizing plate precursor A-1 were replaced. The obtained polarizing plate B1 is a polarizing plate formed by laminating a first adhesive layer, a polarizer, a protective film (first protective film), a second adhesive layer and a brightness enhancement film (second protective film) in this order .

[Production of polarizing plate C]

The first protective film-1 was laminated on one side of the above-mentioned polarizer with an aqueous adhesive interposed therebetween. After lamination, the 1st protective film and the polarizer were bonded together by drying at 80 degreeC for 5 minutes. The polarizer and the bonding surface of the first protective film are opposite On the side surface, the 1st adhesive bond layer laminated|stacked on the mold release film was bonded, and the mold release film was peeled off, and the polarizing plate C was obtained. The obtained polarizing plate is a polarizing plate in which a 1st adhesive bond layer, a polarizer, and a protective film (1st protective film) are laminated|stacked in this order. In addition, regarding the polarizing plate C, the polarizing plate using the 1st protective film-1 is polarizing plate C1, for example, the polarizing plate using the 1st protective film-5 is polarizing plate C5.

[Calculation of dimensional change rate]

About the said protective film, the dimensional change rate difference was measured by the following method.

In addition, in the protective film used in an Example and a comparative example, the width direction is a direction parallel to the transmission axis direction of a polarizer.

First, each long protective film was cut out into a square of 100 mm in the longitudinal direction×100 mm in the width direction. After cutting the protective film, the dimension (L0) in the width direction was measured using a two-dimensional measuring device "NEXIV VMR-12072" (manufactured by Nikon Corporation). Similarly, the dimension in the longitudinal direction was also measured.

Then, the protective film was left to stand at 85° C. for 1 hour (humidity: 5%). After this step, the dimension (L85) in the width direction and the dimension in the longitudinal direction of the protective film were measured in the same manner as described above.

The dimensional change rate (%) was obtained from the following formula, and the dimensional change rate (85° C.) in the width direction of the protective film and the dimensional change rate in the longitudinal direction were calculated.

Dimensional change rate (85℃)=[(L0-L85)/L0]×100

Furthermore, after calculating the dimensional change rate in an environment of 85°C, the same sample was left at a temperature of 23°C and a humidity of 55% for 15 minutes, and then at 30°C and a relative humidity of 95% for 0.5 hours. After this step, the dimension (L30) and the length in the width direction of the protective film were measured in the same manner as described above. dimension in degrees. The dimensional change rate (%) was obtained from the following formula, and the dimensional change rate in the width direction and the dimensional change rate in the longitudinal direction of the protective film were calculated. In addition, "L030" means that after measuring the dimensional change rate (85°C) in the direction parallel to the transmission axis direction of the polarizer (the longitudinal direction or the width direction), it is left at a temperature of 23°C and a humidity of 55% for 15 minutes. The size of the film after.

Dimensional change rate (30℃)=[(L030-L30)/L0]×100

The absolute value of the difference between the obtained dimensional change rate (85°C) and the dimensional change rate (30°C) was calculated. These results are shown in Table 1. In addition, "FTD" in a table|surface is an abbreviation which shows the absolute value of the difference of a dimensional change rate (85 _degreeC ) and a dimensional change rate (30 degreeC). In addition, the F _PZ of the polarizer was also measured by the same method as above.

Then, ΔF _TD (the difference between the absolute value F _PZ of the difference in the dimensional change rate of the polarizer and the absolute value F _PF of the difference in the dimensional change rate of the protective film) was calculated. Furthermore, the ratio of ΔF _TD to F _PZ (ΔF _TD /F _PZ ) was calculated. The results are shown in Table 1.

[Table 1]

[Cold and heat shock environment test and condensation cold and heat shock environment test]

The polarizing plate with the adhesive layer prepared as described above was cut out to 100 mm×60 mm, the release film was peeled off from the first adhesive layer side, and the adhesive layer was bonded to a glass plate via the exposed adhesive layer. The obtained samples for evaluation were subjected to a thermal shock environment test and a dew condensation thermal shock environment test described later.

[Cold and heat shock environmental test]

The thermal shock environment test is performed with a thermal shock test device (product name "TSA-71L-A-3" sold by ESPEC Co., Ltd.) under high temperature conditions (85 °C) holding time of 30 minutes and low temperature conditions (-40 °C) holding time of 30 minutes as one cycle. In addition, when the temperature transition time was set to 1 minute, and the temperature transition time at the time of temperature transition was set to 0 minutes, the conditions were set so that no outside air was introduced and dew condensation did not occur on the optical member. A test in which this cycle was repeated for 400 cycles was performed.

[Condensation cold and heat shock environmental test]

The dew condensation thermal shock environment test was carried out in the above-mentioned thermal shock environment test, and was conducted under the condition that condensation occurred on the optical member by introducing external air into the device for 5 minutes during temperature transition. A test in which this cycle was repeated for 40 cycles was performed.

In this test, the temperature of the outside air was 23°C and the relative humidity was 55%.

[determination]

After the thermal shock environment test (number of cycles: 400 times) and the dew condensation thermal shock environment test (number of cycles: 400 times), the presence or absence of cracks was visually confirmed. No change before the test, no light leakage under the crossed Nichol after the test is "○"; after the test, the light leakage under the crossed Nichol is "X".

In addition, the maximum length of cracks that occurred in the sample after the dew condensation thermal shock environment test was performed was measured under crossed Nicols. The results obtained in the thermal shock environmental test and the condensation thermal shock environmental test are shown in Table 2.

[Table 2]

It can be seen from the results that the polarizing plate of the present invention has good effects in both the cold-heat shock environment test and the dew condensation cold-heat shock environment test. That is, according to the present invention, it is possible to provide a polarizing plate with good durability without the occurrence of light leakage from the polarizer under high temperature conditions and high humidity conditions. Moreover, even if In the environment of repeated high temperature and low temperature, the polarizing plate of the present invention will not cause light leakage, cracking, etc., and can exhibit good polarizing properties.

Furthermore, the polarizing plate of the present invention has a significantly shorter maximum length of cracks caused by dew condensation and thermal shock environmental testing than that of the polarizing plate of the comparative example. Therefore, the polarizing plate of the present invention can suppress the growth of cracks in the polarizing plate even under high humidity conditions where dew condensation occurs, and can maintain good polarization characteristics.

[Environmental test of thermal shock after thrusting]

Pressure wounds were formed on the surface of the polarizer, and the polarizer was subjected to a thermal shock environment test to confirm whether the polarizer was cracked. Specifically, the evaluation was performed through the following steps.

The polarizing plate prepared as described above was cut into 100 mm × 60 mm, the release film on the first adhesive layer was peeled off, and the polarizing plate was bonded to an alkali-free glass (manufactured by Corning, Inc.) through the first adhesive layer. , EAGLE XG (registered trademark)). At 1.0 mm from the end of the polarizing plate attached to the glass, a load of 3 N was applied to the surface of the polarizing plate using a scratch hardness tester (manufactured by Erichsen, Germany, model 318, ball diameter 0.75 mm). , imparts crushing. The depth of the pressure wound was 1 μm or less, and the size was 0.2 mm in diameter.

Then, 1.0 mm from the end of the other polarizing plate attached to the glass was applied with a scratch hardness tester of 5 N, and a load of 10 N was applied to the surface of the other polarizing plate to prepare a sample.

The injury caused by the so-called operation of applying a load to the surface of the polarizing plate can be assumed to be usually caused by using tweezers on the protective film laminated on the polarizing plate. Injuries that occur when a sharp tool such as a child is peeled off, or when a backlight and a polarizing plate are bonded together in a state where foreign objects are intertwined.

For the polarizing plate whose surface was crushed by applying a load of 3N, 5N, or 10N, a thermal shock environment test (250 cycles) at temperatures of 85°C and -40°C (each 30 minutes as one cycle) was performed. The determination is performed as follows. The results are shown in Table 3.

[determination]

When any kind of load is applied, the case where no light leakage of the polarizer occurs under the cross-Nicol after the thermal shock environment test is "○". When any kind of load is applied, the polarizer is broken after the thermal shock environment test, and the light leakage can be confirmed under the crossed Nicole or visually as "X".

[table 3]

(industrial availability)

According to the present invention, it is possible to provide a polarizing plate that is less likely to leak light and has excellent durability even under high temperature conditions and high humidity conditions. And, namely Even in the environment of repeated high temperature and low temperature, the polarizing plate of the present invention does not produce light leakage, cracks, etc., and can exhibit good polarizing properties. Furthermore, according to the present invention, the polarizer can be thinned, and even when scratches occur on the surface of the protective film, cracking of the polarizer can be suppressed.

This case claims priority based on Japanese Patent Application No. 2015-223443 filed on November 13, 2015 and Japanese Patent Application No. 2016-079655 filed on April 12, 2016, and the entire contents of the description are incorporated herein by reference.

11: Polarizer

12: Protective film (1st protective film)

13: Adhesive layer (1st adhesive layer)

100, 110: polarizer

Claims (6)

A polarizing plate comprising a polarizer, a protective film and an adhesive layer; wherein, the protective film, the polarizer and the adhesive layer are arranged in this order, and the adhesive layer is in direct contact with the polarizer to be laminated, When the dimensional change rate of the protective film in the direction parallel to the transmission axis direction of the polarizer under the condition of 85°C and a relative humidity of 5% for 1 hour is set as the dimensional change rate of the protective film (85°C ), and the dimensional change rate of the protective film after 0.5 hours under the condition of 30°C relative humidity of 95% in a direction parallel to the transmission axis direction of the polarizer is set as the dimensional change rate of the protective film ( 30°C), the absolute value of the difference between the dimensional change rate (85°C) of the protective film and the dimensional change rate (30°C) of the protective film was 0.02 to 0.50, and the storage elastic modulus of the adhesive layer at 23°C was 0.02 to 0.50. The number is 0.01MPa to 1MPa. The polarizing plate according to claim 1, wherein the polarizing plate has a thickness of 10 μm or less. The polarizing plate according to claim 1 or 2, wherein the dimensional change rate of the polarizer in the transmission axis direction under the condition of 85°C relative humidity of 5% for 1 hour after 1 hour is set as the dimensional change of the polarizer rate (85°C), the dimensional change rate of the aforementioned polarizer in the transmission axis direction at 30°C and a relative humidity of 95% after 0.5 hours is set as the dimensional change rate of the polarizer (30°C), the aforementioned polarizer The absolute value of the difference between the dimensional change rate (85°C) of the sheet and the dimensional change rate (30°C) of the polarizer is set as F _PZ , and the dimensional change rate (85°C) of the protective film and the dimensional change of the protective film are set as F PZ . The absolute value of the difference in rate (30°C) is set as F _PF , the difference between the aforementioned F _PZ minus the aforementioned F _PF is set as ΔF _TD , and the ratio of ΔF _TD to F _PZ (ΔF _TD /F _PZ ) is in the range of 0.5 to 0.95. The polarizing plate according to claim 1 or 2, wherein the protective film is made of cellulose ester-based resin, polyester-based resin, polycarbonate-based resin, (meth)acrylic resin, or at least two of these. A transparent resin film composed of a mixture of more than one species. A liquid crystal display device obtained by laminating the polarizing plate according to any one of claims 1 to 4 on a liquid crystal cell with the adhesive layer interposed therebetween. An organic electroluminescent display device, which is obtained by laminating the polarizing plate according to any one of claims 1 to 4 on an organic electroluminescent display via the adhesive layer.

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