TW201726395A - 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 DEG C) of the protective film and the dimensional change rate (30 DEG C) 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 DEG C and 5% relative humidity in the direction parallel to the transmission axis direction of the polarizer being defined as the dimensional change rate (85 DEG C) of the protective film, and the dimensional change rate of the protective film after 0.5 hours under conditions of 30 DEG C and 95% relative humidity in the direction parallel to the transmission axis direction of the polarizer being defined as the dimensional change rate (30 DEG C) of the protective film.

Description

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

The present invention relates to polarizing plates that can be used in a variety of optical applications. Further, the present invention relates to a liquid crystal display device and an organic electroluminescence display device including the polarizing plate.

The polarizing plate is widely used as a polarizing supply element of a display device such as a liquid crystal display device, and as a polarized sensing element. For such a polarizing plate, a polarizer obtained by stretching and dyeing a polyvinyl alcohol film is suitably used.

A polarizing plate is disclosed in which the linear expansion of the protective film is smaller than the linear expansion of the polarizing plate in the direction of the transmission axis, and the more the crack (crack) of the polarizer is, the more the polarizing plate is disclosed. less. According to Patent Document 1, the crack (crack) of the polarizer is evaluated by repeating the test of the step of simply raising and lowering the temperature between -40 ° C and 85 ° C (thermal shock acceleration test). The evaluation of the linear expansion described in Patent Document 1 is generally a parameter of temperature dependence.

Moreover, in recent years, thin polarizing plates and polarizers have been required. Was required to be thinned.

[Previous Technical Literature] [Patent Literature]

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

However, the polarizer produced by stretching has a problem that cracking (cracking) is likely to occur along the direction of the extension axis. For example, if the polarizing plate is exposed to an environment having a severe temperature change, the polarizer may be cracked. An optical defect such as an appearance defect or light leakage occurs. With the thinning of the polarizing plate in recent years, the polarizing plate is more likely to be broken, and a solution has been sought.

Further, since the polarizer containing polyvinyl alcohol has low resistance to humidity, its use under high humidity conditions is limited.

For example, in the invention described in Patent Document 1, evaluation is performed based on linear expansion. However, generally, the evaluation method based on the linear expansion is represented by the parameter of the temperature dependency. Therefore, in the cited document 1, the relationship between the crack (crack) of the polarizer and the humidity is not considered.

Further, in order to satisfy the demand for thinning the polarizing plate, when the polarizing plate is thinned, for example, when the surface of the protective film is scratched, the film-shaped polarizing plate is also broken.

SUMMARY OF THE INVENTION An object of the present invention is to provide a polarizing plate which does not leak light even under conditions of exposure to high temperature and high humidity. Furthermore, the object of the present invention is Provided is a polarizing plate that suppresses occurrence of appearance defects such as rupture of a polarizer in an environment where high temperature and low temperature are repeated.

The invention includes the following.

[1] A polarizing plate comprising a polarizer, a protective film, and an adhesive layer; wherein, when the protective film is in a direction parallel to a direction of a transmission axis of the polarizer, a relative humidity of 5% is 85° C. The dimensional change rate after one hour elapsed is set to a dimensional change ratio (85 ° C) of the protective film, and the protective film has a relative humidity of 95% in a direction parallel to the transmission axis direction of the polarizing plate at 30 ° C. The dimensional change rate after the lapse of 0.5 hours is the dimensional change rate (30 ° C) of the protective film, and the dimensional change rate (85 ° C) of the protective film and the dimensional change rate (30 ° C) of the protective film. The absolute value of the difference is 0.02 to 0.50.

[2] The polarizing plate according to the above [1], wherein a dimensional change ratio of the polarizer after one hour has elapsed in a direction of a penetration axis of 85 ° C and a relative humidity of 5% is set as a size change of the polarizer. Rate (85 ° C), the dimensional change rate of the polarizer after 0.5 hours in the direction of the transmission axis at 30 ° C relative humidity of 95% is set as the dimensional change rate (30 ° C) of the polarizer, and the polarized light is used. The absolute value of the difference between the dimensional change ratio (85 ° C) of the sheet and the dimensional change ratio (30 ° C) of the polarizer is F _PZ , the dimensional change ratio (85 ° C) of the protective film and the dimensional change of the protective film. The absolute value of the difference of the rate (30 ° C) is set to F _PF , and the difference between the F _PZ minus the aforementioned F _PF is set to 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], wherein the polarizer, the protective film, and the adhesive layer are arranged in this order.

[4] The polarizing plate according to [1], 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], wherein the protective film is a cellulose ester resin, a polyester resin, a polycarbonate resin, or a (meth)acrylic resin. A resin or a transparent resin film composed of at least two or more kinds of mixtures.

[6] A liquid crystal display device in which a polarizing plate according to any one of the above [1] to [5] is laminated on a liquid crystal cell via a pressure-sensitive adhesive layer.

[7] An organic electroluminescence display device, which is obtained by laminating a polarizing plate according to any one of the above [1] to [5] on an organic electroluminescence display via a pressure-sensitive adhesive layer.

According to the present invention, it is possible to provide a polarizing plate which is excellent in durability by suppressing cracking and cracking of the polarizer even under high temperature conditions and high humidity conditions. Further, in the environment where high temperature and low temperature are repeated, even in the environment where condensation occurs, the polarizing plate of the present invention does not cause light leakage, rupture of the polarizer, and the like, and exhibits good polarization characteristics. Therefore, the polarizing plate of the present invention can be suitably used without causing light leakage, cracking, or the like under various conditions such as high temperature conditions and high humidity conditions which are not conventionally applicable.

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

11‧‧‧ polarizer

12‧‧‧Protective film (first protective film)

13‧‧‧Adhesive layer (1st adhesive layer)

22‧‧‧2nd protective film

23‧‧‧2nd adhesive layer

40‧‧‧ glass substrate

100, 110‧‧‧ polarizing plate

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

Fig. 2(a) is a schematic plan view showing the axial angle of the transmission axis and the absorption axis in the polarizing plate having the transmission axis (solid line) in the width direction, and Fig. 2(b) shows the wear in the longitudinal direction. A schematic plan view of the axis of the transmission axis and the absorption axis in the polarizing plate of the through-axis (solid line).

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

Hereinafter, although the polarizing plate of the present invention will be described using a suitable diagram, the present invention is not limited to the embodiments.

Fig. 1 is a schematic cross-sectional view showing an example of a preferred layer configuration of a polarizing plate of the present invention. In the first diagram (a), the polarizing plate 100 is formed by laminating the polarizer 11, the protective film 12, and the adhesive layer 13. Similarly, in the first drawing (b), the polarizing plate 110 is formed by laminating the protective film 12, the polarizing plate 11, and the adhesive layer 13. As described above, 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 has a function of converting light such as natural light into linear polarized light, and the polarizer generally has a transmission axis and an absorption axis. The direction of the transmission axis of such a polarizer is understood to be the direction of vibration 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 absorption axis direction of the polarizer is consistent with the direction in which it extends.

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

In the present invention, the dimensional change rate after one hour elapsed at 85 ° C and a relative humidity of 5% was measured according to the following formula. In addition, the dimensional change rate after one hour of the condition of 85 ° C and a relative humidity of 5% is described as a dimensional change rate (85 ° C).

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

Further, the dimensional change ratio after one hour of the direction of the transmission axis of the polarizer at 850 ° C and the relative humidity of 5% is described as the dimensional change ratio (85 ° C) of the polarizer.

Hereinafter, in order to explain, the dimensional change rate (85 ° C) of the protective film and the dimensional change ratio (85 ° C) of the polarizer are only described as the dimensional change ratio (85 ° C).

Dimensional change rate (85 ° C) = [(L0-L85) / L0] × 100 [wherein, L0 represents a film size of a film which is cut in a direction parallel to the direction of the transmission axis of the polarizer (longitudinal direction or width direction), and L85 represents a condition of 5% under the condition of a relative humidity of 85 ° C; After the hour, the film size is in a direction (longitudinal direction or width direction) parallel to the direction of the transmission axis of the polarizer. ]

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

The dimensional change rate (85 ° C) thus calculated can be expressed as either a positive value (i.e., shrinkage) or a negative value (i.e., expansion). A protective film having a positive dimensional change rate (85 ° C) is, for example, a polyolefin resin selected from the group consisting of a chain polyolefin resin and a cyclic polyolefin resin; A cellulose ester-based resin of an acid ester or cellulose diacetate; a (meth)acrylic resin selected from polymethyl methacrylate resin (PMMA resin) or the like.

In the present invention, in the present invention, the calculation of the dimensional change rate after 0.5 hours under the condition of a relative humidity of 95% at 30 ° C is based on the following formula for the film after the dimensional change rate (85 ° C) has been measured. The measurement was carried out. In addition, under the condition of 30 ° C relative humidity of 95%, 0.5 small The dimensional change rate after the time is described as the dimensional change rate (30 ° C).

For example, in the present invention, the dimensional change rate of the protective film after 0.5 hours in a direction parallel to the direction of the transmission axis of the polarizer at 30 ° C and a relative humidity of 95% is described as a protective film. The case of dimensional change rate (30 ° C). On the other hand, the dimensional change rate after 0.5 hours in a direction parallel to the direction of the transmission axis 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, in order to explain, the dimensional change rate (30 ° C) of the protective film and the dimensional change rate (30 ° C) of the polarizing film may be described only as the dimensional change ratio (30 ° C).

Dimensional change rate (30 ° C) = [(L030 - L30) / L0] × 100 [wherein L030 represents a change in the dimension in a direction parallel to the direction of the transmission axis of the polarizer (longitudinal direction or width direction) The size of the film after the rate (85 ° C), and L30 represents a film in a direction (longitudinal direction or width direction) parallel to the direction of the transmission axis of the polarizing plate after 0.5 hour at 30 ° C and a relative humidity of 95%. size of. ]

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

The dimensional change rate (30 ° C) thus calculated can be expressed as either a positive value (ie, contraction) or a negative value (ie, expansion). The protective film having a positive dimensional change rate (30° C.) is, for example, a polyolefin resin such as a chain polyolefin resin or a cyclic polyolefin resin; or a polyester resin; For example, polyethylene terephthalate.

On the other hand, a protective film having a negative dimensional change (expansion) of a dimensional change rate (30 ° C) is, for example, a cellulose ester resin such as cellulose triacetate or cellulose diacetate, And a (meth)acrylic resin, such as a 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 range of the present invention, the sign of the dimensional change rate (85 ° C) and the dimensional change rate (30) The symbols of °C) can all be the same symbol (positive, negative or zero) or different symbols.

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

In the polarizing plate of the present invention, by having an absolute value of the difference in dimensional change ratio in such a range, it is possible to provide a polarizing plate which is excellent in durability by suppressing occurrence of cracking of the polarizing plate under high temperature conditions and high humidity conditions and suppressing light leakage. . Further, even in the environment where high temperature and low temperature are repeated, the polarizing plate of the present invention does not cause light leakage, cracking, or the like, and exhibits good polarization characteristics.

Further, the polarizing plate having the protective film having such characteristics can thin the polarizing plate and suppress cracking of the polarizing film even when scratches occur on the surface of the protective film.

In a preferred embodiment, the polarizing plate of the present invention has a dimensional change rate of the polarizer after one hour of passing through the polarizing plate at a relative humidity of 5% at 85 ° C. The change rate (85 ° C), the dimensional change rate of the polarizer after 0.5 hours in the direction of the transmission axis at 30 ° C relative humidity of 95% is set as the dimensional change rate (30 ° C) of the polarizer, The absolute value of the difference between the dimensional change ratio (85 ° C) of the polarizer and the dimensional change ratio (30 ° C) of the polarizer is F _PZ , and the dimensional change ratio (85 ° C) of the protective film and the size of the protective film. The absolute value of the difference of the rate of change (30 ° C) is F _PF , and when the difference from the aforementioned F _PZ minus the aforementioned F _PF is ΔF _TD , it is expressed by _{ΔF TD} =F _PZ -F _PF , the size The method of calculating the rate of change 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 from 0.55 to 0.95, and more preferably from 0.60 to 0.95.

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

Since the polarizer and the protective film have such a relationship, it is possible to provide a polarizing plate which is excellent in durability without causing light leakage or cracking under high temperature conditions and high humidity conditions. Further, even in the environment where high temperature and low temperature are repeated, the polarizing plate of the present invention does not cause light leakage, cracking, or the like, and exhibits good polarization characteristics. Furthermore, there is a bias of the protective film having such characteristics. The light plate can thin the polarizer and suppress cracking of the polarizer even when scratches on the surface of the protective film.

In a preferred embodiment, the polarizing plate of the present invention is a polarizing plate in which the polarizer, the protective film and the adhesive layer are arranged in this order. In other preferred embodiments, the polarizing plate of the present invention is a polarizing plate in which the protective film, the polarizer, and the adhesive layer are 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 subsequent layer is, for example, 0.01 μm to 5 μm. The layer of the agent can be used in the art.

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

For example, Fig. 2(a) shows an outline of the axial angle of the transmission shaft 11a and the absorption axis 11b in the polarizing plate 100 having the transmission axis 11a of the polarizer in the width direction and the absorption axis 11b having the polarizer in the longitudinal direction. Floor plan. Fig. 2(b) is a schematic plan view showing the axial angle of the transmission shaft 11a and the absorption axis 11b in the polarizing plate 100 having the transmission axis 11a of the polarizer in the longitudinal direction and the absorption axis 11b having the polarizer in the width direction. .

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

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

[Polarizer]

The polarizer may be a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and aligned on one axis. When the thickness of the polarizer is usually 20 μm or less, the polarizing plate can be thinned. In the present invention, for example, a polarizer having a thickness of 10 μm or less, preferably a polarizer of 8 μm or less can be used. Moreover, the polarizer of the present invention usually has a thickness of 2 μm or more.

As the polyvinyl alcohol-based resin, those obtained by saponifying a polyvinyl acetate-based resin can be used. The polyvinyl acetate-based resin may, for example, be a polyvinyl acetate which is a homopolymer of vinyl acetate, and may be a copolymer of, for example, vinyl acetate and another monomer copolymerizable therewith. Other monomers copolymerizable with vinyl acetate may, for example, be an unsaturated carboxylic acid, an olefin, a vinyl ether, an unsaturated sulfonic acid, or an acrylamide having an ammonium group.

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 polyvinyl alcohol, and for example, the polyvinyl alcohol may be modified by an olefin such as ethylene or propylene; acrylic acid, methacrylic acid or crotonic acid; A saturated carboxylic acid; an alkyl ester of an unsaturated carboxylic acid; and acrylamide. 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, still more preferably from 2,000 to 5,000.

Polarized sheet, for example, by polyvinyl alcohol The raw material film composed of the fat is subjected to one-axis stretching, 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 one-axis extension of the polyvinyl alcohol-based resin film can be carried out before the dyeing of the dichroic dye, or simultaneously with the dyeing of the dichroic dye, or after the dyeing of the dichroic dye. When the one-axis extension is performed after the dyeing of the dichroic dye, the one-axis extension may be performed before the boric acid treatment or in the boric acid treatment. Of course, one-axis extension can also be performed in the plurality of stages. To implement one-axis extension, it can be extended by rollers with different rotation speeds, or by being clamped by hot rollers. Further, it may be a dry stretching which is extended in the atmosphere, or may be a wet stretching which is extended in a state of being expanded by a solvent. The final stretching 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 to adsorb the dichroic dye to the film. In the dyeing treatment, for example, a polyvinyl alcohol-based resin film may be immersed in an aqueous solution containing a dichroic dye. The dichroic dye system specifically uses iodine or a dichroic dye.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine and potassium iodide and dyed is usually used. The content of iodine in the aqueous solution is usually about 0.01 to 0.5 parts by weight based on 100 parts by weight of water; and the content of potassium iodide is usually about 0.5 to 10 parts by weight based on 100 parts by weight of water. The temperature of the aqueous solution is usually about 20 to 40 ° C, and the immersion time for 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 in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing a water-soluble dichroic dye and dyed is usually used. The content of the dichroic dye in the aqueous solution is usually about 1 × 10 ^-3 to 1 × 10 ^-2 parts by weight based on 100 parts by weight of water. The aqueous solution may also contain an inorganic salt such as sodium sulfate. The temperature of the aqueous solution is usually about 20 to 80 ° C, and the immersion time for the aqueous solution is usually about 30 to 300 seconds.

The boric acid treatment is carried out, for example, by immersing the dyed polyvinyl alcohol-based resin film in an aqueous boric acid solution. The content of boric acid in the aqueous boric acid solution is usually from about 2 to 15 parts by weight, preferably from 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, the aqueous boric acid solution preferably contains potassium iodide. The content of potassium iodide in the aqueous boric acid solution is usually from about 2 to 20 parts by weight, preferably from 5 to 15 parts by weight, per 100 parts by weight of water. The immersion time for the aqueous boric acid solution is usually about 100 to 1200 seconds, preferably 150 seconds or longer, more preferably 200 seconds or longer, and is preferably 600 seconds or shorter, more preferably 400 seconds or shorter. The temperature of the aqueous boric acid solution is usually 50 ° C or higher, preferably 50 to 85 ° C. As the pH adjuster, sulfuric acid, hydrochloric acid, acetic acid, ascorbic acid or the like may be added to the aqueous boric acid solution.

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

[protective film]

As described above, the protective film of the present invention has an absolute value of a difference between a dimensional change ratio (85 ° C) of the protective film and a dimensional change ratio (30 ° C) of the protective film of 0.02 to 0.50.

The protective film is laminated on at least one side of the polarizer. Further, it is also possible to use a single-layer protective film (first protective film) of the polarizer and another protective film (second protective film) in another area. It is preferably a single-layer protective film (first protective film) of the polarizer. The first protective film and the second protective film may be a single layer, or may be formed by laminating a plurality of films by an adhesive or an adhesive.

Each of the protective film (first protective film) and the second protective film may be a transparent resin film made of a thermoplastic resin. Examples of the thermoplastic resin include a polyolefin resin such as a chain polyolefin resin and a cyclic polyolefin resin, and a cellulose such as cellulose triacetate or 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. Further, a copolymer of at least two or more kinds of monomers constituting the above resin may also be used.

The cyclic polyolefin-based resin is generally a general term for a resin obtained by polymerizing a cyclic olefin as a polymerization unit, and for example, JP-A: A resin described in, for example, Japanese Laid-Open Patent Publication No. Hei. No. Hei. Specific examples of the cyclic polyolefin-based resin include a ring-opened (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, and a chain olefin such as ethylene or propylene and a cyclic olefin. The copolymer (representatively referred to as a random copolymer), and a graft copolymer modified with an unsaturated carboxylic acid or a derivative thereof, and the like, and the like. Among them, a norbornene-based resin having a norbornene-based monomer such as a norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is preferably used.

Cyclic polyolefin resins are sold in various commercial products. An example of a commercially available product of a cyclic polyolefin-based resin is sold under the trade name "TOPAS" (registered trademark) and JSR Co., Ltd., which are produced by TOPAS ADVANCED POLYMERS GmbH and sold by Polyplastics Co., Ltd. in Japan. "ARTON" (registered trademark) sold by the company, "ZEONOR" (registered trademark) and "ZEONEX" (registered trademark) sold by Japan ZEON Co., Ltd., "APEL" (registered trademark) sold by Mitsui Chemicals Co., Ltd., etc. .

Further, a film-formed cyclic polyolefin-based resin film can be used as the protective film. An example of the commercial product is "ARTON FILM" sold by JSR Co., Ltd. ("ARTON" is a registered trademark of the company), and "ESCENA" sold by Sekisui Chemical Industry Co., Ltd. (registered) "Trademark" and "SCA40", "ZEONOR FILM" (registered trademark) sold by Japan ZEON Co., Ltd., etc.

A cellulose ester resin is usually an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include, for example, cellulose triacetic acid. Ester, cellulose diacetate, cellulose tripropionate, cellulose dipropionate, and the like. Further, those copolymers or a part of a hydroxyl group may be modified by other substituents. Among these, cellulose triacetate (triethyl fluorenyl cellulose: TAC) is particularly preferred. Many products of cellulose triacetate are commercially available, and it is also advantageous from the viewpoint of availability and cost. An example of a commercial product of cellulose triacetate is represented by a trade name, such as "Fujitac (registered trademark) TD80", "Fujitac (registered trademark) TD80UF", "Fujitac (registered trademark) sold by Fujifilm Co., Ltd. ) TD80UZ" and "Fujitac (registered trademark) TD40UZ", TAC film "KC8UX2M", "KC2UA" and "KC4UY" manufactured by Konica Minolta Co., Ltd.

Polymethacrylate and polyacrylate (hereinafter, a case where polymethacrylate and polyacrylate are collectively referred to as a (meth)acrylic resin) can be easily obtained from the market.

Examples of the (meth)acrylic resin include a homopolymer of an alkyl methacrylate or an alkyl acrylate, a copolymer of an alkyl methacrylate and an alkyl acrylate, and the like. Specific examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and the like; and, as the alkyl acrylate, specifically, for example, methyl acrylate , ethyl acrylate, propyl acrylate, and the like. Further, as such a (meth)acrylic resin, a commercially available general-purpose (meth)acrylic resin can be used, and a (meth)acrylic resin can also be referred to as an impact-resistant (meth)acrylic resin.

The (meth)acrylic resin is usually a polymer mainly composed of methacrylate. Methacrylate, which can be a methacrylic acid The homopolymer of the ester may also be a copolymer of methacrylate and other methacrylate or acrylate. The methacrylate may, for example, be an alkyl methacrylate such as methyl methacrylate, ethyl methacrylate or butyl methacrylate, and the alkyl group has a carbon number of usually about 1 to 4. Further, a cycloalkyl methacrylate such as cyclopentyl methacrylate or cyclohexyl methacrylate; an aryl methacrylate such as phenyl methacrylate; or a methyl group such as cyclohexylmethyl methacrylate; A cycloalkyl acrylate; an aryl methacrylate such as benzyl methacrylate.

The other polymerizable monomer which can constitute the (meth)acrylic resin may, for example, be an acrylate or a polymerizable monomer other than methacrylate or acrylate. The acrylate type may use an alkyl acrylate, and specific examples thereof include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, and acrylic acid 2 An alkyl acrylate having 1 to 8 carbon atoms in an alkyl group such as ethylhexyl ester, cyclohexyl acrylate or 2-hydroxyethyl acrylate. The alkyl group preferably has 1 to 4 carbon atoms. In the (meth)acrylic resin, one type of the acrylate may be used alone or two or more types may be used in combination.

The polymerizable monomer other than the methacrylate and the acrylate may, for example, be a monofunctional monomer having one polymerizable carbon-carbon double bond in the molecule or have at least two polymerizable carbon-carbon double bonds in the molecule. A polyfunctional monomer is preferred, and a monofunctional monomer is preferred. Specific examples of the monofunctional monomer include styrene monomers such as styrene, α-methylstyrene, vinyltoluene, halogenated styrene, and hydroxystyrene; and vinyl cyanide such as acrylonitrile or methacrylonitrile. Acrylic acid, methacrylic acid, maleic anhydride, An unsaturated acid such as methylene succinic anhydride; N-methyl maleimide, N-cyclohexyl maleimide, N-phenyl maleimide, etc. Dimerimide; allyl alcohol such as methacryl alcohol, allyl alcohol; vinyl acetate, ethylene chloride, ethylene, propylene, 4-methyl-1-pentene, 2- Other monomers such as hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, N-vinyl carbazole.

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 ester of unsaturated carboxylic acid such as allyl acrylate, allyl methacrylate, allyl cinnamate; diallyl phthalate, diallyl maleate, melamine An aromatic polyalkenyl compound such as a polyalkenic acid such as a triallyl ester or a trially isocyanuric acid or a divinylbenzene. The polymerizable monomer other than the methacrylate and the acrylate may be used alone or in combination of two or more.

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

Further, since the (meth)acrylic resin can improve the durability of the film, it has a ring structure in the polymer main chain. The ring structure is preferably a heterocyclic structure such as a cyclic anhydride structure, a cyclic quinone imine structure, or a lactone ring structure. Made. Specific examples thereof include a glutaric anhydride structure, a cyclic acid anhydride structure such as succinic anhydride, a cyclic quinone imine structure such as a glutarylene imine structure or a succinimide structure; butyrolactone and valerolactone; Ester ring structure. The more the content of the ring structure in the main chain, the higher the glass transition temperature of the (meth)acrylic resin. The cyclic acid anhydride structure and the cyclic quinone imine structure can be introduced by a method of copolymerizing a monomer having a cyclic structure such as maleic acid or maleimide, and dehydrating after polymerization. ‧ A method in which a methanol anhydride condensation reaction is introduced to introduce a cyclic acid anhydride structure, a method in which an amine compound is introduced into a cyclic quinone imine structure, or the like is introduced. A resin (polymer) having a lactone ring structure can be prepared by using a polymer having a hydroxyl group and an ester group in a polymer chain, and then a hydroxyl group and an ester group of the obtained polymer are used as a catalyst such as an organic phosphorus compound. There is a method in which condensation condensation is performed by heating to form a lactone ring structure.

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

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

(meth)acrylic resin, which may also contain the above (meth) Other resins than acrylic resins. The content ratio of the other resin is preferably from 0 to 70% by weight, more preferably from 0 to 50% by weight, still more preferably from 0 to 30% by weight. The resin may be, for example, an olefin-based polymer such as polyethylene, polypropylene, an ethylene-propylene copolymer or poly(4-methyl-1-pentene); a halogen-containing polymer such as a vinyl chloride or a vinyl chloride resin; ; styrene-based 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 or polybutyl succinate; polycarbonate; , nylon 66, nylon 610 and other polyamines; polyacetal; polyphenylene ether; polyphenylene sulfide; polyether ether ketone; polyether nitrile; polyfluorene; polyether oxime; polyoxybenzylene (polyoxybenzylene); Amidoxime and the like.

The (meth)acrylic resin may contain rubber particles from the viewpoint of improving impact resistance and film forming properties 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 of a layer exhibiting rubber elasticity and other layers. Examples of the rubber elastic system include an olefin-based elastic polymer, a diene-based elastic polymer, a styrene-diene-based elastic polymer, and an acrylic elastomeric polymer. Among them, from the viewpoint of light resistance and transparency, it is preferred to use an acrylic elastomer.

The acrylic elastomeric polymer is mainly composed of an alkyl acrylate, that is, a polymer containing 50% by weight or more of a constituent unit derived from an alkyl acrylate based on the total amount of monomers. The acrylic elastomeric polymer may be a homopolymer of an alkyl acrylate, or may comprise 50% by weight. A copolymer derived from a constituent unit of an alkyl acrylate and 50% by weight or less of a constituent unit derived from another polymerizable monomer.

The alkyl acrylate constituting the acrylic elastomer polymer is usually an alkyl group having 4 to 8 carbon atoms. Examples of the other polymerizable monomer described above include, for example, alkyl methacrylate such as methyl methacrylate or ethyl methacrylate; styrene monomers such as styrene and alkyl styrene; and acrylonitrile. a monofunctional monomer such as an unsaturated nitrile such as methacrylonitrile; or an ester of an unsaturated carboxylic acid such as allyl (meth)acrylate or methacrylic acid (meth)acrylate; a difunctional ester of a dibasic acid such as diallyl acid; a polyfunctional monomer such as an unsaturated carboxylic acid diester of a diol such as an alkanediol di(meth)acrylate.

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

An example of a monomer composition of a polymer mainly composed of an alkyl methacrylate which is a "hard polymer layer formed on the outer side or the inner side of the layer of the acrylic elastomer polymer" is a (meth)acrylic acid system. Examples of the monomer composition of the polymer mainly composed of an alkyl methacrylate listed as an example of the resin are the same, and a monomer composition mainly composed of methyl methacrylate is preferably used. The acrylic rubber elastomer particles having such a multilayer structure can be described, for example, in Japanese Patent Publication No. 55-27576. Method of manufacture.

From the viewpoint of the film formability of the (meth)acrylic resin, the impact resistance of the film, and the smoothness of the surface of the film, the rubber particles are preferably bonded to the rubber elastomer layer (the layer of the acrylic elastic polymer) contained therein. The average particle diameter up to 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, and still more preferably 300 nm or less, still more preferably 280 nm or less.

The average particle diameter until the rubber elastic layer (layer of the acrylic elastic polymer) in the rubber particles was measured by the following method. In other words, when such a rubber particle is mixed with a (meth)acrylic resin and thinned, and when the cross section is dyed with an aqueous solution of cerium oxide, only the rubber elastic layer is colored, and a slightly round shape is observed, but the mother layer is observed. The methacrylic resin was not dyed. Then, from the cross section of the film thus dyed, a sheet was prepared using a microtome or the like and observed under an electron microscope. Then, 100 dyed rubber particles were randomly selected, and the respective particle diameters (diameters up to the rubber elastic layer) were calculated, and the average value thereof was used as the average particle diameter. Since the measurement was carried out by such a method, the obtained average particle diameter was 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 (a layer of an acrylic elastic polymer) is wrapped therein, if it is mixed with a methyl group of the precursor In 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 cerium oxide and observed under 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 inner layers, acrylic When the elastic polymer and the outer layer are rubber particles of a two-layer structure of a hard polymer mainly composed of methyl methacrylate, the acrylic elastic polymer portion of the inner layer is dyed, and particles having a single layer structure are observed. Further, when the rubber particles are the innermost layer, the 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 the rubber particles of the layer structure, the central portion of the innermost layer of the particles is not dyed, and only the acrylic elastic polymer portion of the intermediate layer is dyed, and the particles having the two-layer structure are observed.

From the viewpoint of the film formability of the (meth)acrylic resin, the impact resistance of the film, and the smoothness of the surface of the film, the blending ratio of the rubber particles is the same as that of the (meth)acrylic resin film. The basis of the total amount of the acrylic resin is preferably 3% by weight or more and 60% by weight or less, more preferably 45% by weight or less, still more preferably 35% by weight or less. When the rubber elastomer particles are more than 60% by weight, the dimensional change of the film is increased, and the heat resistance is lowered. On the other hand, when the rubber elastomer particles are less than 3% by weight, the heat resistance of the film is good, but the windability at the time of film formation is poor, and the productivity is low. Further, in the present invention, when the rubber elastic particles are particles having a multilayer structure having a layer exhibiting rubber elasticity and other layers, the weight of a portion composed of a layer exhibiting rubber elasticity and a layer inside thereof is regarded as It is the weight of the rubber elastomer particles. For example, when the acrylic rubber elastomer particles having the above three-layer structure are used, the total weight of the acrylic polymer portion of the intermediate layer and the hard polymer portion of the innermost layer mainly composed of methyl methacrylate is regarded. It is the weight of the rubber elastomer particles. When the acrylic rubber elastomer particles having the above three-layer structure are dissolved in acetone, The acrylic elastomeric polymer portion of the intermediate layer and the hard polymer portion mainly composed of methyl methacrylate in the innermost layer remain as insoluble components, so that the acrylic rubber particles having a three-layer structure can be easily obtained. The total weight ratio of the intermediate layer to the innermost layer.

When the (meth)acrylic resin film contains rubber particles, the (meth)acrylic resin composition containing rubber particles used in the production of the film can be made of (meth)acrylic resin and rubber. The particles are obtained by mixing by melt-kneading or the like, and may be obtained by polymerizing a monomer composition which is a raw material of a methacrylic resin in the presence of rubber particles.

A usual additive such as an ultraviolet absorber, an organic dye, a pigment, an inorganic dye, an antioxidant, an antistatic agent, a surfactant, or the like may be contained in the protective film. Among them, the ultraviolet absorber is preferred because it improves weather resistance. Examples of the ultraviolet absorber include, for example, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2- Phenol], 2-(5-methyl-2-hydroxyphenyl)-2H-benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl Phenyl]-2H-benzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(3-tert-butyl-5 -methyl-2-hydroxyphenyl)-5-chloro-2H-benzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)-5-chloro-2H-benzo Triazole, 2-(3,5-di-third-pentyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(2'-hydroxy-5'-trioctylphenyl)-2H a benzotriazole-based ultraviolet absorber such as benzotriazole; 2-hydroxy-4-methoxydiphenyl ketone, 2-hydroxy-4-octyloxydiphenyl ketone, 2,4-di Hydroxydiphenyl ketone, 2-hydroxy-4-methoxy-4'-chlorodiphenyl ketone, 2-hydroxydiphenyl ketone such as 2,2'-dihydroxy-4-methoxydiphenyl ketone or 2,2'-dihydroxy-4,4'-dimethoxydiphenyl ketone UV absorber; phenylphenyl salicylate-based UV absorber such as p-tert-butylphenyl salicylate or p-octylphenyl salicylate; 2,4-diphenyl-6-(2- Hydroxy-4-methoxyphenyl)-1,3,5-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-three Oxazine, 2,4-diphenyl-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-[1-octyloxy Carboxycarbonylethoxy]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) Oxy]-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-triazin-2-yl]-5-(octyloxy)phenol, 2-[2,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl ]-5-octyloxyphenol, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexyl)ethoxy A triazine-based ultraviolet absorber such as phenol or 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methoxyphenyl)-1,3,5-triazine. Two or more of these may be used as needed.

A commercially available product can be used as the ultraviolet absorber, and for example, a triazine-based ultraviolet absorber is manufactured by CHEMPRO Chemical Co., Ltd. "Kemisorb 102" (registered trademark), "ADEKA STAB (registered trademark) LA46", "ADEKA STAB (registered trademark) LAF70" manufactured by ADEKA Co., Ltd., "TINUVIN (registered trademark) 460", "TINUVIN", manufactured by BASF Corporation (registered trademark) 405", "TINUVIN (registered trademark) 400" and "TINUVIN (registered trademark) 477", "CYASORB (registered trademark) UV-1164" (all of which are trade names) manufactured by Sun Chemical Co., Ltd., etc. . For the benzotriazole-based ultraviolet absorbers, for example, "ADEKA STAB LA31" and "ADEKA STAB LA36" manufactured by ADEKA Co., Ltd., "SUMISORB (registered trademark) 200" and "SUMISORB" (registered by Chem Chemical Co., Ltd.) "Kemisorb 74" (registered trademark), "Kemisorb", manufactured by CHEMPRO Chemical Co., Ltd., and "Kemisorb (registered trademark) 340", "SUMISORB (registered trademark) 340" and "SUMISORB (registered trademark) 350" 79" (registered trademark) and "Kemisorb 279" (registered trademark), "TINUVIN (registered trademark) 99-2", "TINUVIN (registered trademark) 900" and "TINUVIN (registered trademark) 928" (above) All are product names) and so on. When the (meth)acrylic resin film contains an ultraviolet absorber, the amount thereof is usually 0.1% by weight or more, preferably 0.3% by weight or more, based on 100% by weight of the (meth)acrylic resin. Preferably it is 3% by weight or less.

In the production of a (meth)acrylic resin film, a conventional film forming method can be employed. The (meth)acrylic resin film may have a multilayer structure, and the (meth)acrylic resin film of a multilayer structure may be a method using a feed block, using a multi-manifold die. Various methods of the conventional methods such as methods. Among them, for example, a product is laminated via a feed module and multi-layer melt extrusion molding is performed from a T-die to obtain a product. A method of forming a film by contacting at least one side of a film with a roller or a belt is preferred because a film having a good surface property can be obtained. In particular, from the viewpoint of improving the surface smoothness and surface gloss of the (meth)acrylic resin film, it is preferred that both sides of the laminated film obtained by the above-described multilayer melt extrusion molding contact the surface of the roller or the surface of the belt. A method of thinning. In the roller or the belt used at this time, the surface of the roller or the surface of the belt which is in contact with the (meth)acrylic resin film is smoothed to the surface of the (meth)acrylic resin film, and the surface is mirrored. Preferably.

The (meth)acrylic resin film can be obtained by subjecting the film produced as described above to an extension treatment. In order to obtain a film having desired optical characteristics and mechanical properties, an extension treatment is sometimes required. The stretching treatment may be, for example, one-axis extension, two-axis extension, or the like. The direction of extension may be, for example, a 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 two-axis extension may be a two-axis extension extending simultaneously in two extending directions, or may be a two-axis extension extending in a specified direction and then extending in other directions.

The first protective film and the second protective film may be protective films having optical functions such as a retardation film and a brightness enhancement film as long as they are included in the scope of the present invention. For example, a retardation film can be formed by extending a transparent resin film made of the above material (one-axis stretching or biaxial stretching or the like) or forming a liquid crystal layer or the like on the film.

The first protective film and the second protective film can form 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 on the surface opposite to the polarizer. ). Surface shape of the protective film As a method of treating the surface layer, a conventional method can be used.

The first protective film and the second protective film may be the same protective film or may be different protective films. Examples of the case where the protective film is different are a combination of at least different types of thermoplastic resins constituting the protective film; presence or absence of an optical function of the protective film or a combination of at least different kinds thereof; and a surface treatment layer formed on the surface The presence or absence of a combination of at least different types or the like.

The thickness of the first protective film and the second protective film is preferably thinner from the viewpoint of thinning of the polarizing plate, but when it is too thin, the strength is lowered and the workability is deteriorated. 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 (first protective film) can easily obtain the effects of the present invention as long as it has an appropriate dimensional change by water absorption. It is preferably a transparent resin film composed of a cellulose ester resin, a polyester resin, a polycarbonate resin, a (meth)acrylic resin, or a mixture of at least two or more thereof, and more preferably a fiber. A transparent resin film comprising a sol-ester resin, a (meth)acrylic resin, or a mixture of at least two of these.

(adhesive)

The adhesive for forming the adhesive layer can be appropriately selected as long as it is conventionally used, and is not affected by peeling or the like in a high-temperature environment, a moist heat environment, or a repeated high-temperature and low-temperature environment in which the polarizing plate is exposed. Sexuality can be. Specific examples thereof include an acrylic adhesive, a silicone adhesive, and a rubber adhesive. From the viewpoint of transparency, weather resistance, heat resistance, and processability, an acrylic adhesive is used. Very good.

In the adhesive, a filler, a plasticizer, a glass fiber, a glass bead, a metal powder, a filler composed of other inorganic powder, a pigment, a colorant, a filler, an antioxidant, and the like may be appropriately formulated as needed. Various additives such as an ultraviolet absorber, an antistatic agent, and a decane coupling agent.

The adhesive layer is usually formed by applying a solution of the adhesive to the release sheet and drying it. The coating on the release sheet may be, 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, or a dip coating method. , spraying method, etc. The release sheet provided with the adhesive layer is utilized by a method of transferring it or the like. The thickness of the adhesive layer is usually from about 3 to 100 μm, preferably from 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, shrinkage of the polarizing plate at the time of high-temperature test cannot be suppressed, and appearance defects such as peeling tend to occur. Further, when the storage elastic modulus of the adhesive layer is more than 1 MPa, the adhesive does not relax the deformation between the glass and the polarizing plate during the thermal shock test, and the polarizing plate tends to be cracked.

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

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

According to the polarizing plate of the present invention, a polarizing plate which is thin and excellent in strength can be provided.

(Example)

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the examples. In the examples, the % and the parts indicating the content or the amount used are based on weight unless otherwise specified.

[Manufacture of polarizer]

A polyvinyl alcohol film having a thickness of 20 μm (average degree of polymerization 2,400, average saponification degree: 99.9 mol% or more) was stretched to about 5 times by dry stretching, and then immersed in pure water at 60 ° C for 1 minute while maintaining tension. Thereafter, it was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.05/5/100 at 28 ° C for 60 seconds. Then, it was immersed at 72 ° C for 300 seconds in an aqueous solution of potassium iodide / boric acid / water in a weight ratio of 8.5 / 8.5 / 100. Then, 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 which was obtained by iodine adsorption to a polyvinyl alcohol film.

[1st adhesive]

A commercially available adhesive sheet was used in a release-treated area of a polyethylene terephthalate film (release film) having a thickness of 38 μm subjected to release treatment, and an acrylic adhesive layer having a thickness of 20 μm was used. . In the acrylic adhesive, no urethane acrylate oligomer is formulated. 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.

[2nd adhesive layer]

An organic solvent solution obtained by adding an amine ester acrylate oligomer and an isocyanate crosslinking agent to a copolymer of butyl acrylate and acrylic acid, and applying it to a thickness of 38 μm subjected to release treatment by a knife coater The release-treated surface of the ethylene terephthalate film (release film) was dried to have a thickness of 5 μm after drying to obtain an adhesive sheet in which an adhesive layer was laminated. 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.

[First Protective Film-1]

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

[First Protective Film-2]

Use the trade name "KC2UA" made by Konica Minolta Co., Ltd., An unstretched TAC film having a thickness of 25 μm.

[First Protective Film-3]

A cycloolefin resin film (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 13 μm was used. The in-plane retardation value (Re(590)) at a wavelength of 590 nm = 0.8 nm, the thickness difference in the thickness direction at a wavelength of 590 nm (Rth(590)) = 3.4 nm, and the retardation value in the thickness direction at a wavelength of 483 nm (Rth ( 483)) = 3.5 nm, phase difference value (Rth (755)) = 2.8 nm in the thickness direction at a wavelength of 755 nm.

[First Protective Film-4]

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

[First Protective Film-5]

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

[First Protective Film-6]

The first protective film-1 was dissolved in 1,3-dioxolane to prepare 12% by weight, and was applied onto a glass substrate using a bar coater (No. 60) to After drying in an oven at 60 ° C for 3 minutes so that the thickness after drying became 10 μm, the coating film was peeled off from the glass to obtain a first protective film-6.

[2nd protective film]

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

[Preparation of water-based adhesive]

3 parts of a carboxyl group-modified polyvinyl alcohol (KL-318, manufactured by Kuraray Co., Ltd.) was dissolved in 100 parts of water, and a polyamine amine epoxy-based additive belonging to a water-soluble epoxy compound was added to the aqueous solution ( SUMIREZ RESIN (registered trademark) 650 (30) manufactured by CHEMITEX Co., Ltd., and an aqueous solution having a solid concentration of 30%, 1.5 parts, was used as a water-based adhesive.

[Production of Polarizing Plate Precursor A]

The first protective film-1 is laminated on one surface of the polarizer via a water-based adhesive. After lamination, the first protective film-1 and the polarizer were bonded by drying at 80 ° C for 5 minutes. The second adhesive layer laminated on the release film is bonded to the surface of the polarizer opposite to the bonding surface of the first protective film-1. The first adhesive layer laminated on the release film is bonded to the surface of the first protective film-1 opposite to the bonding surface of the polarizer.

Further, the direction in which the transmission axis of the polarizer is parallel to the width direction of the protective film is bonded.

In this manner, the polarizing plate precursor A-1 in which the first adhesive layer, the protective film, the polarizer, and the second adhesive layer were laminated in this order was produced.

Similarly, the first protective film-2 was used instead of the first protective film-1, and a polarizing plate precursor was used as the polarizing plate precursor A-2. A polarizing plate precursor was also produced in the same manner for other protective films.

[Production of Polarizing Plate A]

The release film on the second adhesive layer of the polarizing plate precursor is peeled off. The second adhesive layer of the polarizing plate precursor A is bonded to the brightness enhancement film to obtain a first adhesive layer, a protective film (first protective film), a polarizer, a second adhesive layer, and a brightness enhancement film (No. 2 protective film) The polarizing plate A laminated in this order. For example, a polarizing plate made of the first protective film-1 is a polarizing plate A1. Similarly, the polarizing plate A2 having the thus configured configuration using the first protective film-2 is a polarizing plate A2.

[Production of Polarizing Plate B]

The polarizing plate B1 was produced in the same manner as the polarizing plate A1 except that the laminated position of the polarizer and the protective film in the polarizing plate precursor A-1 was interchanged. The obtained polarizing plate B1 is a polarizing plate in which the first adhesive layer, the polarizer, the protective film (first protective film), the second adhesive layer, and the brightness enhancement film (second protective film) are laminated in this order. .

[Production of Polarizing Plate C]

The first protective film-1 is laminated on one surface of the polarizer via a water-based adhesive. After lamination, the first protective film was bonded to the polarizer by drying at 80 ° C for 5 minutes. The opposite of the bonding surface of the polarizer and the first protective film On the side surface, the first adhesive layer laminated on the release film was bonded, and then the release film was peeled off to obtain a polarizing plate C. The obtained polarizing plate is a polarizing plate in which the first adhesive layer, the polarizer, and the protective film (first protective film) are laminated in this order. In the polarizing plate C, the polarizing plate using the first protective film-1 is the polarizing plate C1, and for example, the polarizing plate using the first protective film-5 is the polarizing plate C5.

[Calculation of dimensional change rate]

With respect to the above protective film, the dimensional change rate difference was measured by the following method.

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

First, each of the long protective films was cut into a square having a length of 100 mm × a width of 100 mm. After the protective film was cut, 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 allowed 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 above.

The dimensional change rate (%) was determined by 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 ° C) = [(L0-L85) / L0] × 100

Further, after calculating the dimensional change rate in an environment of 85 ° C, the same sample was allowed to stand at a temperature of 23 ° C and a humidity of 55% for 15 minutes, and then allowed to stand at 30 ° C and a relative humidity of 95% for 0.5 hour. After this step, the dimension (L30) and length of the protective film in the width direction were measured in the same manner as above. The size of the dimension. The dimensional change rate (%) was determined by the following formula, and the dimensional change rate in the width direction of the protective film and the dimensional change rate in the longitudinal direction were calculated. In addition, "L030" means that the dimensional change rate (85 ° C) is measured in a direction (longitudinal direction or width direction) parallel to the direction of the transmission axis of the polarizer, and then 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 ° C) = [(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. The results are shown in Table 1. In addition, "F _TD " in the table indicates an abbreviation of the absolute value of the difference between the dimensional change rate (85 ° C) and the dimensional change rate (30 ° C). Further, the F _{PZ of the} polarizer was also measured by the same method as described above.

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

[Cold and hot shock environment test and condensation condensation thermal shock environment test]

The polarizing plate with the adhesive layer prepared as described above was cut into 100 mm × 60 mm, and the release film was peeled off from the side of the first adhesive layer, and bonded to the glass plate via the exposed adhesive layer. The obtained evaluation sample was subjected to a thermal shock environmental test and a dew condensation thermal shock environment test which will be described later.

[Cold and hot shock environment test]

In the cold and hot shock environment test, a thermal shock test device (product name "TSA-71L-A-3" sold by ESPEC Co., Ltd.) is used in a state where the polarizing plate is attached to the glass plate, and the temperature is high (85 °C) The holding time was 30 minutes and the low temperature condition (-40 ° C) was maintained for 30 minutes in 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 0 minute, it was set as the condition which does not introduce an external air, and does not decondense an optical member. A test that repeats the cycle for 400 cycles is performed.

[Condensation cold and hot shock environment test]

The condensation condensation thermal shock environment test was carried out in the above-mentioned thermal shock environmental test under the condition that the external air was introduced into the apparatus for 5 minutes while the temperature was moving, and the optical member was intended to be dew condensation. A test that repeats the cycle for 40 cycles is carried out.

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

[determination]

After the thermal shock environmental test (cycle number: 400 times) and the condensation thermal shock environment test (cycle number: 400 times), the presence or absence of cracks was visually confirmed. There was no change before the test. If the light leakage did not occur under crossed Nichol after the test, it was "○"; after the test, the light leakage occurred under the cross Nikoel was "X".

Moreover, the maximum length of cracking of the sample was measured under crossed Nichols in the sample after the condensation condensation thermal shock environment test. The results obtained in the thermal shock environmental test and the condensation thermal shock environmental test are shown in Table 2.

From the results, it is understood that the polarizing plate of the present invention has a good effect in both the thermal shock environmental test and the condensation thermal shock environment test. That is, according to the present invention, it is possible to provide a polarizing plate in which the polarizer does not leak light under high temperature conditions and high humidity conditions and has excellent durability. And even if In the environment where high temperature and low temperature are repeated, the polarizing plate of the present invention does not cause light leakage, cracking, etc., and exhibits good polarization characteristics.

Further, in the polarizing plate of the present invention, the maximum length of the crack generated by the condensation thermal shock environmental test was significantly shorter than that of the polarizing plate of the comparative example. Therefore, the polarizing plate of the present invention can suppress the growth of the crack of the polarizer even under high humidity conditions in which dew condensation occurs, and can maintain good polarizing characteristics.

[Cold and hot shock environment test after spurs]

A crushing was formed on the surface of the polarizing plate, and the polarizing plate was subjected to a thermal shock environmental test to confirm the presence or absence of cracking of the polarizing plate. Specifically, the evaluation is performed through the following steps.

The polarizing plate prepared as described above was cut into 100 mm × 60 mm, and the release film on the first adhesive layer was peeled off, and the polarizing plate was bonded to the alkali-free glass via the first adhesive layer (manufactured by Corning Incorporated) , EAGLE XG (registered trademark)). A load of 3N was applied to the surface of the polarizing plate by a scratch hardness tester (manufactured by Erichsen, Germany, model 318, ball diameter 0.75 mm) at a distance of 1.0 mm from the end of the polarizing plate attached to the glass. , giving crush injuries. The depth of the crush is 1 μm or less and the size is 0.2 mm in diameter.

Further, a sample was prepared by applying a thickness of 1.0 N from the end portion of the other polarizing plate bonded to the glass by a scratch type durometer and applying a load of 10 N to the other polarizing plate.

The injury caused by the operation of imparting weight to the surface of the polarizing plate can be assumed to be generally used for the protective film laminated on the polarizing plate. When the sharp device such as a child is peeled off, or when the backlight is bonded to the polarizing plate, the wound is caused when the foreign matter is bonded.

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

[determination]

When any of the load was applied, after the thermal shock environmental test, the light leakage of the polarizer did not occur under the cross Nikoel was "○". When any load is applied, the polarizer is broken after the thermal shock environment test, and the "X" is confirmed under cross Nikon or visually.

(industrial use possibility)

According to the present invention, it is possible to provide a polarizing plate which is less likely to cause light leakage even under high temperature conditions and high humidity conditions and has excellent durability. And that is In the environment where the high temperature and low temperature are repeated, the polarizing plate of the present invention does not cause light leakage, cracking, or the like, and exhibits good polarization characteristics. Further, according to the present invention, the polarizer can be thinned, and even if the surface of the protective film is scratched, the crack of the polarizer can be suppressed.

The priority of the Japanese Patent Application No. 2015- 223 443, filed on Nov. 13, 2015, and the Japanese Patent Application No. 2016-079655, filed on Apr. 12, 2015, is hereby incorporated by reference.

11‧‧‧ polarizer

12‧‧‧Protective film (first protective film)

13‧‧‧Adhesive layer (1st adhesive layer)

100, 110‧‧‧ polarizing plate

Claims (7)

A polarizing plate comprising a polarizer, a protective film and an adhesive layer; wherein, when the protective film is in a direction parallel to the transmission axis direction of the polarizer, the relative humidity of 5% is 85° C. The dimensional change rate after the hour is set to the dimensional change rate (85 ° C) of the protective film, and the protective film is in a direction parallel to the transmission axis direction of the polarizing plate at a relative humidity of 95% at 30 ° C. When the dimensional change rate after 0.5 hours is the dimensional change rate (30 ° C) of the protective film, the difference between the dimensional change ratio (85 ° C) of the protective film and the dimensional change ratio (30 ° C) of the protective film is absolute. The value is 0.02 to 0.50. The polarizing plate according to the first aspect of the invention, wherein the dimensional change rate of the polarizer after 1 hour in a direction of a penetration axis of 85 ° C and a relative humidity of 5% is set as a size of the polarizer. The change rate (85 ° C), the dimensional change rate of the polarizer after 0.5 hours in the direction of the transmission axis at 30 ° C relative humidity of 95% is set as the dimensional change rate (30 ° C) of the polarizer, The absolute value of the difference between the dimensional change ratio (85 ° C) of the polarizer and the dimensional change ratio (30 ° C) of the polarizer is F _PZ , and the dimensional change ratio (85 ° C) of the protective film and the size of the protective film. The absolute value of the difference of the rate of change (30 ° C) is set to F _PF , and the difference between the F _PZ minus the F _PF is set to 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 polarizer, the protective film, and the adhesive layer are arranged in this order. The polarizing plate according to claim 1 or 2, wherein the protective film, the polarizer, and the adhesive layer are arranged in this order. The polarizing plate according to any one of the preceding claims, wherein the protective film is a cellulose ester resin, a polyester resin, a polycarbonate resin, or a (meth)acrylic acid. A resin or a transparent resin film comprising at least two or more of these mixtures. A liquid crystal display device in which a polarizing plate according to any one of claims 1 to 5 is laminated on a liquid crystal cell via the pressure-sensitive adhesive layer. An organic electroluminescence display device according to any one of claims 1 to 5, wherein the polarizing plate is laminated on the organic electroluminescent display device via the adhesive layer.