TWI701468B - Polarizing plate and method for inspecting the same - Google Patents

Abstract

An objective of this invention is to provide a thin polarizing plate in which crack of polarizer is difficult to occur. Furthermore, an objective of this invention is to provide a polarizing plate in which poor appearance such as crack of a polarizer is suppressed in an environment with repeated high and low temperatures.

The polarizing plate of this invention is laminated with a first adhesive layer, a first protective film including a cellulose ester resin, a polarizer with a thickness of 10 μm or thinner, a second adhesive layer, and a second protective film, wherein the second protective film has scratches on at least one of the surface at a side of the second protective film opposite to the second adhesive layer and the surface at the second adhesive layer side of the second protective film, and the scratch is at least one of a scratch having a length of 0.001 to 500 μm, a width of 0.001 to 500 μm and a depth of 0.001 to 10 μm, and a scratch having a depth of 0.001 to 10 μm and an area of 0.001 to 1.0 mm².

Description

Polarizing plate and inspection method of polarizing plate

The present invention relates to a polarizing plate that can be used for various optical applications. Moreover, the present invention relates to an inspection method of a polarizing plate.

In recent years, mobile terminals such as smart phones have rapidly progressed toward larger screens and thinner designs from the aspect of design or portability. In order to achieve long-term driving with a limited thickness, high brightness and thinner polarizers are also desired.

In order to solve such expectations, generally, a protective film composed of transparent resin bonded to both sides of the polarizer is arranged on one side, and the polarizer with the brightness enhancement film is further bonded. For example, Patent Document 1 has disclosed a thin and high-profile protective film composed of a transparent resin, a polarizer that adsorbs and orients iodine on a polyvinyl alcohol film, a pressure-sensitive adhesive layer, and a brightening film. Brightness polarizer.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2010-039458 A

However, as a result of the progress of the thinning of the polarizer, in the polarizer described in Cited Document 1, if the polarizer is used under repeated high and low temperature environments, cracks will occur in the polarizer.

Such cracking of the polarizer is caused by foreign matter being bitten into the surface of the protective film during the manufacturing process of the polarizer, foreign matter biting into the protective film when the protective film is laminated, and processing of the polarizer, etc., caused near the end of the polarizer surface. Caused by the scars.

With the thinning of polarizers in recent years, cracking of polarizers is more likely to occur, so a solution is sought.

Therefore, the purpose of the present invention is to provide a thin polarizer that is not prone to cracks in the polarizer. Furthermore, the object of the present invention is to provide a polarizing plate that can suppress the appearance of poor appearance such as cracks and light leakage of the polarizer even when used in an environment that is repeatedly high and low temperature.

The present invention includes the following.

[1] A polarizing plate that is laminated with: a first adhesive layer, a first protective film containing cellulose ester resin, a polarizer with a thickness of 10 μm or less, a second adhesive layer, and a second protective film, Wherein, at least one of the second protective film on the side opposite to the second adhesive layer in the second protective film and the surface on the second adhesive layer side in the second protective film has The scar, the aforementioned scar is at least one of a length of 0.001 to 500 μm, a width of 0.001 to 500 μm, and a depth of 0.001 to 10 μm, and a depth of 0.001 to 10 μm and an area of 0.001 to 1.0 mm ² .

[2] The polarizing plate described in [1], which is laminated in this order: the first adhesive layer, the first protective film, the polarizer, the second adhesive layer, and the second protection membrane.

[3] The polarizing plate according to [1] or [2], in which the second protective film has a scratch on the surface of the second protective film opposite to the second adhesive layer.

[4] The polarizing plate according to any one of [1] to [3], wherein the second protective film is a brightness enhancement film.

[5] A method of inspecting a polarizing plate, the polarizing plate is laminated with: a first adhesive layer, a first protective film containing cellulose ester resin, a polarizer with a thickness of 10 μm or less, a second adhesive layer, and For the second protective film, it includes the following steps: (1) the step of measuring the maximum size of the scar in the second protective film; (2) attaching the maximum size of the scar in the second protective film to the second protective film At least one of the surface of the film on the opposite side to the second adhesive layer and the surface of the second protective film on the side of the second adhesive layer has a length of 0.001 to 500 μm, a width of 0.001 to 500 μm, and The maximum size of the polarizing plate with a depth of 0.001 to 10 μm and/or the scar in the second protective film is on the surface of the second protective film opposite to the second adhesive layer and in the second protective film At least one of the surfaces on the side of the second adhesive layer is a polarizing plate with a depth of 0.001 to 10 μm and an area of 0.001 to 1.0 mm ² and a step of judging as a good product.

The polarizing plate of the present invention does not cause light leakage, cracking, etc. of the polarizer even under repeated high and low temperature environments, and exhibits good polarization characteristics.

In addition, the polarizing plate of the present invention is a thin polarizing plate with excellent strength and durability.

11‧‧‧Polarizer

12‧‧‧The first protective film

13‧‧‧The first adhesive layer

22‧‧‧Second protective film

23‧‧‧Second adhesive layer

100‧‧‧Polarizer

Fig. 1 is a schematic cross-sectional view illustrating a preferable layer structure in the polarizing plate of the present invention.

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

In the present invention, the polarizing plate is laminated with: a first adhesive layer, a first protective film, a polarizer with a thickness of 10 μm or less, a second adhesive layer, and a second protective film. The laminated layers are not special limited. In a preferred aspect, as shown in FIG. 1, the polarizing plate 100 of the present invention may have a layer of sequentially laminated: a first adhesive layer 13, a first protective film 12, a polarizer 11, and a second adhesive layer 23. The structure of the second protective film 22.

The polarizer in the present invention has a thickness of 10 μm or less and has a function of converting light such as natural light into linear polarized light. Preferably, the polarizer has a thickness of 8 μm or less. In addition, the polarizer in the present invention usually has a thickness of 2 μm or more.

The second protective film in the present invention is that the surface of the second protective film opposite to the second adhesive layer and/or the surface of the second protective film on the side of the second adhesive layer has a scar, and the scar is the length At least one of 0.001 to 500 μm, 0.001 to 500 μm in width, and 0.001 to 10 μm in depth, and at least one of 0.001 to 10 μm in depth and 0.001 to 1.0 mm ² in area.

Because the second protective film has such a size scar, even in the repeated high and low temperature environment, the polarizing plate of the present invention does not cause light leakage, cracks, etc. and can show good polarization characteristics. The reason is uncertain, but the first protective film contains cellulose ester resin, the difference between the behavior of the first protective film and the behavior of the polarizer under repeated high and low temperature environments is reduced, so that it can be applied to polarized light. The power of the film is reduced. Moreover, it is believed that the second protective film in the polarizing plate has scars in the above range on its surface. When thermal shock is applied under repeated high and low temperature environments, the scars are used as the starting point and the stress inside the polarizing plate can easily escape. Therefore. On the other hand, scars exceeding the above-mentioned range may themselves cause deterioration of visibility.

Therefore, the "scar" in the present invention is not limited in shape as long as the size of the scar is included in the above range. For example, including linear scars, polygonal scars, curved scars, plural scars and divergent scars (such as scratches), depressions (such as cylinders, polygonal columns, cones, polygonal cones, and tapers) Wait.

In addition, as for the "scar" in the present invention, as long as the size of the scar is included in the above range, the size of the scar, such as the depth and width, can vary. For example, a spot with a scar has a depth of 6 μm, and another spot with a scar may have a depth of 7 μm.

The measurement system of the size of such scars can use commonly used methods, such as laser light measurement and microscope measurement.

The size of the scar in the present invention is determined by measuring the maximum size of the largest scar in the second protective film.

In addition, the area of the scar means the area in a plane parallel to the plane of the second protective film.

That is, the area of the scar does not need to consider the depth of the scar, and only the area of the scar where the plane of the second protective film is observed is measured. In addition, the area of the scar can be calculated using common methods.

The location of the scar is not particularly limited. For example, in the entire area of the film surface, there may be scars randomly. It is preferable that scars exist on the surface end of the second protective film.

It is preferable that the surface of the second protective film on the opposite side to the second adhesive layer has scratches.

At this time, the scar has a size of 0.001 to 500 μm in length, 0.001 to 500 μm in width, and 0.001 to 10 μm in depth, for example.

In addition, it is sufficient that at least one flaw exists on the surface of the second protective film, and it exists at a density of 0.0001 to 0.001 per mm ² . For example, in the case of a polarizing plate with a size of 65mm×130mm, there may be about 0.8 to about 8.5 scratches. If the number of scars exceeds such a range, the haze value of the polarizing plate will increase, and the optical properties of the polarizing plate will become insufficient.

In addition, the shape of the scars formed in the depth direction of the second protective film may be formed in a vertical direction with respect to the plane of the second protective film, or may be formed in an oblique direction with respect to the plane of the second protective film, also It can be a combination of these shapes.

The method for forming scars is not particularly limited. For example, it is also possible to use the foreign matter bitten into the surface of the protective film during the manufacturing process of the polarizer, the bite of foreign matter when the protective film is laminated, and the treatment of the polarizer. Scars generated near the end of the surface. Moreover, when manufacturing the polarizing plate, for example, a predetermined flaw may be provided on the surface end of the second protective film. At this time, a scratch-type hardness tester or the like is used to provide scratches on the surface end of the second protective film.

As long as the size of the scar in the present invention is included in the above range, it may be a scar with a combination of dimensions described below.

The length of the scar is preferably 0.001 to 500 μm, more preferably 0.001 to 400 μm. In addition, when it is a scar that has been bent, the length of the scar is expressed as the total length of the scar.

The width of the scar is preferably 0.001 to 500 μm, more preferably 0.001 to 400 μm.

The depth of the scar is 0.001 to 10 μm, more preferably 1 to 10 μm.

For example, a concave scar has an area of 0.01 to 1.0 mm ² , preferably has an area of 0.1 to 0.50 mm ² , and more preferably has an area of 0.1 to 0.25 mm ² .

In a preferred embodiment, the scar has a length of 0.001 to 500 μm, a width of 0.001 to 500 μm, and a depth of 0.001 to 10 μm.

In a more preferred embodiment, the scar has a depth of 0.001 to 10 μm and an area of 0.001 to 1.0 mm ² .

[Polarizer]

The polarizer in the present invention generally has a transmission axis and an absorption axis. The direction of the transmission axis of such a polarizer can be understood as the vibration direction of the transmitted light when the polarizer transmits natural light. On the other hand, the absorption axis of the polarizer is orthogonal to the penetration axis of the polarizer. In addition, the polarizer can generally be a stretched film, and the direction of the absorption axis of the polarizer is consistent with its extension direction.

In the present invention, the term "direction parallel to the direction of the transmission axis of the polarizer" refers to the direction of the transmission axis of the above-mentioned polarizer, and a direction that is parallel or slightly parallel (the angle of formation is within ±7 degrees).

The polarizer may be formed by absorbing and orientating the dichroic dye on a polyvinyl alcohol resin layer that is uniaxially stretched.

As the polyvinyl alcohol-based resin, a polyvinyl acetate-based resin saponified can be used. In addition to polyvinyl acetate which is a homopolymer of vinyl acetate, the polyvinyl acetate-based resin may be a copolymer of vinyl acetate and other monomers copolymerizable therewith. Examples of other single systems that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and amide acrylates having ammonium groups.

The saponification degree of the polyvinyl alcohol-based resin may be in the range of 80 mol% or more, but is preferably in the range of 90 mol% or more, and more preferably in the range of 95 mol% or more. The polyvinyl alcohol-based resin may be partially modified polyvinyl alcohol, such as polyvinyl alcohol-based resin using olefins such as ethylene and propylene; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; Unsaturated Modified ones such as carboxylic acid alkyl ester and amide acrylate. The average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 to 10,000, more preferably 1,500 to 8,000, and more preferably 2,000 to 5,000.

For example, the polarizing film can be uniaxially stretched on the embryonic membrane composed of polyvinyl alcohol resin, dyed with dichroic pigment (dyeing treatment), treated with boric acid aqueous solution (boric acid treatment), washed with water (washed treatment), and finally made Manufactured by drying.

The uniaxial stretching system of the polyvinyl alcohol-based resin film may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or may be performed after dyeing with a dichroic dye. When the uniaxial stretching is dyed with a dichroic dye, the uniaxial stretching can be performed before the boric acid treatment or during the boric acid treatment. Also, of course, uniaxial extension can also be performed at these plural stages. The uniaxial stretching system can be stretched through rollers with different peripheral speeds, and can also be stretched by a method of nipping by hot rollers. In addition, it can also be dry stretching in the atmosphere, or wet stretching in a state where the solvent is swollen. The final stretching ratio of the polyvinyl alcohol resin film is usually about 4 to 8 times.

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

When iodine is used as a dichroic dye, a method of immersing a polyvinyl alcohol resin film in an aqueous solution containing iodine and potassium iodide for dyeing is usually adopted. The content of iodine in this aqueous solution is per 100 parts by weight of water. It is usually about 0.01 to 0.5 parts by weight, and the content of potassium iodide is about 0.5 to 10 parts by weight per 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 a dichroic dye, a method of immersing a polyvinyl alcohol resin film in an aqueous solution containing a water-soluble dichroic dye for dyeing is usually adopted. The content of the dichroic dye in this aqueous solution is about 1×10 ^-3 to 1×10 ^-2 parts by weight per 100 parts by weight of water. This aqueous solution may 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 resin film in a boric acid aqueous solution. The content of boric acid in the boric acid aqueous solution is per 100 parts by weight of water, usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight. When iodine is used as the dichroic dye, the boric acid aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid aqueous solution is per 100 parts by weight of water, usually about 2 to 20 parts by weight, preferably 5 to 15 parts by weight. The immersion time of the film in the boric acid aqueous solution is usually about 100 to 1200 seconds, preferably 150 seconds or more, more preferably 200 seconds or more, still more preferably 600 seconds or less, and most preferably 400 seconds or less. The temperature of the boric acid aqueous solution is usually above 50°C, preferably 50 to 85°C. The boric acid aqueous solution can be added with sulfuric acid, hydrochloric acid, acetic acid, ascorbic acid, etc. as a pH adjusting agent.

The polyvinyl alcohol 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 polyvinyl alcohol-based resin film treated with boric acid in water. After washing and drying, a polarizer can be obtained. The temperature of the water in the washing treatment is usually about 5 to 40°C, and the immersion time is usually about 2 to 120 seconds. The drying performed after that is usually performed using a hot air dryer and a 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]

In a preferred embodiment, the first protective film and the polarizer are attached through the adhesive layer. The thickness of the adhesive layer is, for example, 0.001 μm to 10 μm. For the adhesive layer system, those known in the technical field can be used. By bonding the first protective film and the polarizer through the adhesive layer, even in an environment where high and low temperatures are repeated, light leakage and cracking of the polarizer can be suppressed.

In a preferred embodiment, the dimensional change of the first protective film containing cellulose ester resin in the direction parallel to the direction of the transmission axis of the polarizer at 85°C and 5% relative humidity for 1 hour As the dimensional change rate of the protective film (85℃), the dimensional change rate of the protective film in the direction parallel to the transmission axis of the polarizer under the condition of 30℃ and 95% relative humidity for 0.5 hours is used as protection In the case of the dimensional change rate of the film (30°C), the absolute value of the difference between the dimensional change rate of the protective film (85°C) and the dimensional change rate (30°C) of the protective film is, for example, 0.00 to 0.50.

In the present invention, the dimensional change rate after 1 hour under the condition of 85°C and 5% relative humidity is measured according to the following formula.

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

The dimensional change rate of the protective film (85℃)=[(L0-L85)/L0]×100[where, L0 means the direction parallel to the transmission axis of the polarizer (length direction or width direction) The film size of the cut film, L85 means the film size in the direction parallel to the transmission axis of the polarizer (length direction or width direction) after 1 hour at 85°C and 5% relative humidity . ]

For example, when measuring the widthwise dimension (L0) during film cutting, even after standing for 1 hour at 85°C and 5% relative humidity, measure the widthwise dimension (L85) of the film to calculate the dimensional change rate. In addition, after manufacturing the polarizing plate, when measuring the dimension (L0) in the direction parallel to the transmission axis direction of the polarizer in the protective film obtained by removing the polarizer and the like from the polarizing plate, statically at 85°C and 5% relative humidity After setting 1, measure the dimension (L85) in the direction parallel to the transmission axis of the polarizer, and calculate the dimensional change rate.

The dimensional change rate (85°C) calculated in this way can represent either a positive value (that is, shrinkage) or a negative value (that is, expansion). The first protective film containing cellulose ester resin whose dimensional change rate (85°C) is a positive value is composed of, for example, cellulose ester resin selected from cellulose triacetate and cellulose diacetate. .

In the same way as above, in the present invention, the calculation of the dimensional change rate after 0.5 hours under the conditions of 30°C and 95% relative humidity is measured according to the following formula for the film after the measurement of the dimensional change rate (85°C).

For example, in the present invention, in the direction parallel to the transmission axis of the polarizer of the protective film, the dimensional change rate after 0.5 hours under the condition of 30°C and 95% relative humidity may be described as the dimensional change of the protective film Rate (30°C).

Dimensional change rate (30℃)=[(L0 ₃₀ -L30)/L0]×100[In the formula, L0 ₃₀ means measuring in the direction parallel to the transmission axis of the polarizer (length direction or width direction) The film size after the dimensional change rate (85℃), L30 means the direction parallel to the transmission axis of the polarizer (length direction or width direction) after 0.5 hours at 30℃ and 95% relative humidity ) Of the film size. ]

For example, after measuring the dimensional change rate (85°C) and leaving it at a temperature of 23°C and a humidity of 55% for 15 minutes, L0 ₃₀ can be measured.

The dimensional change rate (30°C) calculated in this way can represent either a positive value (that is, shrinkage) or a negative value (that is, expansion).

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

In the present invention, the absolute value of the difference between the dimensional change rate (85°C) of the first protective film and the dimensional change rate (30°C) of the first protective film is preferably 0.00 to 0.50. More preferably, the absolute value of the difference between the dimensional change rate (85°C) of the first protective film and the dimensional change rate (30°C) of the first protective film is 0.02 to 0.30.

The polarizing plate of the present invention is the first protective film in such a range It has the absolute value of the difference in the rate of dimensional change, so that it can further control the cracks and light leakage of the polarizer under high temperature and high humidity conditions, and it can have better durability. Furthermore, a polarizer with a protective film with such characteristics can make the polarizer thinner, and even if the surface of the protective film is scratched, the polarizer can be prevented from cracking.

The first protective film system contains cellulose ester resin. The second protective film may be a transparent resin film composed of a thermoplastic resin. Thermoplastic resins include, for example, polypropylene resins such as chain polyolefin resins and cyclic polyolefin resins and other polyolefin resins; cellulose resins such as cellulose triacetate and cellulose Cellulose ester resins such as diacetate; polyester resins such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; polycarbonate resins; optional (Meth) acrylic resin from polymethacrylate resin; or a mixture of at least two or more of these. In addition, 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 polymerization units. Examples include Japanese Patent Application Publication No. 1-240517, Japanese Patent Application Publication No. 3-14882, Japanese Patent Application Publication No. 3-122137 Resins recorded in bulletins, etc. Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of chain olefins such as ethylene and propylene and cyclic olefins ( Representatives are random copolymers), and graft polymers modified with unsaturated carboxylic acids, their derivatives, and their hydrogenated products. Among them, the use of norbornene, polycyclic norbornene-based monomers, etc. as the ring Norbornene-based resins such as olefins are preferred.

Cyclic polyolefin resins are commercially available as various products. Examples of commercially available products of cyclic polyolefin resins are all under the trade name, TOPAS ADVANCED POLYMERS GmbH, and in Japan, they are "TOPAS" (registered trademark) sold by Polyplastics Co., Ltd., and JSR shares "Arton" (registered trademark) sold by Co., Ltd., "ZEONOR" (registered trademark) and "ZEONEX" (registered trademark) sold by ZEON Co., Ltd., and "Apelle" sold by Mitsui Gakuin Co., Ltd. (Registered trademark) etc.

In addition, a commercially available product of the cyclic polyolefin-based resin film of the produced film can be used as the protective film. Examples of commercially-available products are all products under the trade name, "Arton film" ("Arton" is a registered trademark of the same company) sold by JSR Co., Ltd., "Escena" sold by Sekisui Chemical Industry Co., Ltd. "(Registered trademark) and "SCA40", "ZEONOR film" (registered trademark) sold by ZEON Co., Ltd., etc.

The cellulose ester resin is usually an ester of cellulose and fatty acid. Specific examples of cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. In addition, these copolymers and those in which a part of the hydroxyl group is modified with other substituents can also be used. Among these, cellulose triacetate (triacetyl cellulose: TAC) is particularly preferred. Many products of cellulose triacetate are sold, which are advantageous in terms of ease of acquisition and cost. Examples of commercially available products of cellulose triacetate are "Fijitac (registered trademark) TD80" and "Fujitac (registered trademark) sold by Fuji Film Co., Ltd. under the trade name. Trademark) TD80UF", "Fujitac (registered trademark) TD80UZ" and "Fujitac (registered trademark) TD40UZ", TAC film "KC8UX2M", "KC2UA" and "KC4UY" manufactured by Konica Minolta Co., Ltd.

Polymethacrylate and polyacrylate (hereinafter, aggregate polymethacrylate and polyacrylate may be referred to as (meth)acrylic resin.) series can be easily obtained from the market.

The (meth)acrylic resin system includes, for example, homopolymers of alkyl methacrylate or alkyl acrylate, copolymers of alkyl methacrylate and alkyl acrylate, and the like. Specific examples of alkyl methacrylate include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and the like, and specific examples of alkyl acrylate include methyl methacrylate. Acrylate, ethyl acrylate, propyl acrylate, etc. Such a (meth)acrylic resin system can use a commercially available (meth)acrylic resin for general use. The (meth)acrylic resin system can use what is called an impact-resistant (meth)acrylic resin.

The (meth)acrylic resin is usually a polymer mainly composed of methacrylate. The methacrylic resin may be a homopolymer of one type of methacrylate, or a copolymer of methacrylate and other methacrylates, acrylates, etc. Examples of the methacrylate series 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. In addition, cyclopentyl methacrylate, cyclohexyl methacrylate, cycloalkyl methacrylate such as methacrylic acid, aryl methacrylate such as phenyl methacrylate, cyclohexyl methyl methacrylate, etc. can also be used Cycloalkylalkyl methacrylate, Aralkyl methacrylates such as benzyl methacrylate.

The above-mentioned other polymerizable monomer systems that can constitute the (meth)acrylic resin include, for example, polymerizable monomers other than acrylate, methacrylate, and acrylate. Acrylate-based alkyl acrylates can be used, and specific examples include: methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate and other alkyl acrylates whose alkyl groups have 1 to 8 carbon atoms. The carbon number of the alkyl group is preferably 1 to 4. Among (meth)acrylic resins, acrylic esters may be used alone or in combination of two or more.

Examples of polymerizable monomer systems other than methacrylate and acrylate include monofunctional monomers having one polymerizable carbon-carbon double bond in the molecule, and at least two polymerizable carbons in the molecule. -Multifunctional monomers with carbon double bonds, but it is preferable to use monofunctional monomers. Specific examples of monofunctional monomers include: styrene monomers such as styrene, α-methylstyrene, vinyl toluene, halogenated styrene, and hydroxystyrene; vinyl cyanide such as acrylonitrile and methacrylonitrile; Acrylic acid, methacrylic acid, maleic anhydride, itaconic anhydride and other unsaturated acids; N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, etc. Leximine; Allyl alcohol such as methacrylic alcohol and allyl alcohol; Vinyl acetate, vinyl chloride, ethylene, propylene, 4-methyl-1-pentene, 2-hydroxymethyl-1- Other monomers such as butene, methyl ketene, N-vinylpyrrolidone, and N-vinylcarbazole.

In addition, specific examples of multifunctional monomers include: ethylene glycol dimethacrylate, butanediol dimethacrylate, trimethylolpropane tri Polyunsaturated carboxylic acid esters of polyhydric alcohols such as acrylates; allyl acrylate, allyl methacrylate, allyl cinnamate and other unsaturated carboxylic acid esters; diallyl phthalate, dimaleic acid Polyalkenyl esters of polybasic acids such as allyl ester, triallyl cyanurate, triallyl cyanurate, and aromatic polyene compounds such as divinylbenzene. Polymerizable single systems other than methacrylate and acrylate may be used alone or in combination of two or more.

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

In addition, the (meth)acrylic resin system may have a ring structure in the polymer main chain in terms of improving the durability of the film. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imine structure, and a lactone ring structure. Specifically, cyclic acid anhydride structures such as glutaric anhydride structure and succinic anhydride structure, cyclic anhydride structures such as glutaric anhydride structure and succinimide structure, butyrolactone, valerolactone, etc. Ester ring structure. The more the content of the ring structure in the main chain increases, the more the glass transition temperature of the (meth)acrylic resin can be increased. Cyclic acid anhydride structure and cyclic imine structure can be introduced by copolymerizing monomers with cyclic structure such as maleic anhydride, maleimide, etc., and by dehydration/demethanol condensation after polymerization It is introduced by a method of introducing a cyclic acid anhydride structure by reaction, a method of introducing a cyclic imine structure by reacting an amino compound, and the like. The resin (polymer) with a lactone ring structure is prepared in high After a polymer with a hydroxyl group and an ester group in the molecular chain, the hydroxyl group and the ester group in the resulting polymer are cyclized and condensed in the presence of a catalyst such as an organophosphorus compound by heating to form a lactone ring structure. To make.

For the polymer system having a hydroxyl group and an ester group in the polymer chain, for example, methyl 2-(hydroxymeth)acrylate, ethyl 2-(hydroxymeth)acrylate, isopropyl 2-(hydroxymeth)acrylate, 2-(hydroxymeth)acrylate n-butyl, 2-(hydroxymeth) tertiary butyl acrylate and other (meth)acrylates having hydroxyl and ester groups are prepared as part of the monomer. A more specific preparation method of a polymer having a lactone ring structure is described in, for example, JP 2007-254726 A.

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

The (meth)acrylic resin may contain resins other than the above-mentioned (meth)acrylic resin. The content 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 may be olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly(4-methyl-1-pentene), etc.; halogen-containing polymers such as vinyl chloride and vinyl chloride resins ; Polystyrene, styrene-methacrylic acid methyl copolymer, styrene-acrylonitrile copolymer and other styrene polymers; polyethylene terephthalate, polybutylene terephthalate, poly Polyester such as ethylene naphthalate; polyallylate composed of aromatic diol and aromatic dicarboxylic acid; biodegradable polyester such as polylactic acid and polybutylene succinate; polycarbonate; Nailun 6, Nailun 66, Nailun 610 and other polyamides; poly Acetal; polyphenoxy ether; polyphenylene sulfide; polyether ether ketone; polyether nitrile; poly sulfide; polyether sulfide; polyphenoxy; polyamide imide, etc.

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

The acrylic elastic polymer may be a polymer mainly composed of alkyl acrylate, that is, a polymer containing more than 50% by weight of structural units derived from alkyl acrylate based on the total monomer amount. The acrylic elastomeric polymer may be a homopolymer of alkyl acrylate, or may be 50% by weight or more of structural units derived from alkyl acrylate and 50% by weight of structural units derived from other polymerizable monomers. The following copolymers.

The acrylic alkyl group constituting the acrylic elastic polymer is usually one having 4 to 8 carbon atoms in the alkyl group. Examples of other polymerizable monomers mentioned above, such as methyl methacrylate, ethyl methacrylate and other alkyl methacrylate; styrene, alkyl styrene and other styrene monomers; acrylonitrile, methyl methacrylate Monofunctional monomers such as unsaturated nitriles such as acrylonitrile, and further are allyl (meth)acrylate, methallyl (meth)acrylate and other unsaturated carboxylic acid; diallyl maleate Dienyl esters of other diprotic acids; unsaturated carboxylic acid diesters of glycols, such as alkanediol di(meth)acrylate, etc. body.

The rubber particles containing the acrylic elastic polymer are preferably particles with a multilayer structure having a layer 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 acrylic elastic polymer layer, or further on the inner side of the acrylic elastic polymer layer It has a 3-layer structure with a hard polymer layer mainly composed of alkyl methacrylate.

Examples of the monomer composition in the polymer mainly composed of alkyl methacrylate that constitute the hard polymer layer formed on the outer side or the inner side of the acrylic elastic polymer layer include (meth)acrylic resins The example of the monomer composition of the polymer mainly composed of alkyl methacrylate is the same, and it is particularly preferable to use the monomer composition mainly composed of methyl methacrylate.

The acrylic rubber elastomer particle system of such a multilayer structure can be manufactured according to the method described in Japanese Patent Publication No. 55-27576, for example.

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

The average particle size of the rubber elastomer layer (acrylic elastic polymer layer) in the rubber particles can be measured in the following manner. That is, if such rubber particles are mixed with (meth)acrylic resin, the film The cross section was dyed with an aqueous solution of ruthenium oxide. Only the rubber elastic body layer was colored and observed to be approximately round, and the (meth)acrylic resin of the mother layer was not dyed. Therefore, the section of the film dyed in this way is prepared using a microtome or the like to prepare a slice, and then observed with an electron microscope. Then, after extracting any 100 dyed rubber particles and calculating the respective particle diameters (to the diameter of the rubber elastomer layer), the number average value is used as the average particle diameter. The measurement is carried out in this way, so the average particle diameter obtained above is the average particle diameter coefficient.

The outermost layer is a hard polymer with methyl methacrylate as the main body. When the rubber particles of the rubber elastomer layer (acrylic elastic polymer layer) are encapsulated, it is mixed with the (meth)acrylic resin of the matrix. The outermost layer of the rubber particles will be mixed with the (meth)acrylic resin of the matrix. Therefore, when the cross section was dyed with ruthenium oxide and observed with an electron microscope, the rubber particles were observed as particles with the outermost layer removed. Specifically, when the inner layer is an acrylic elastic polymer and the outer layer is a two-layer structure rubber particle of a hard polymer mainly composed of methyl methacrylate, the acrylic elastic polymer part of the inner layer is dyed and observed as Single layer structure of particles. In addition, when the innermost layer is a hard polymer mainly composed of methyl methacrylate, the middle layer is an acrylic elastic polymer, and the outermost layer is a three-layer structure rubber particle of a hard polymer mainly composed of methyl methacrylate , The central part of the innermost layer of particles is not dyed, but is observed as a two-layer structure particle in which only the acrylic elastic polymer part of the middle layer is dyed.

From the viewpoints of film-forming properties of (meth)acrylic resin, impact resistance of the film, and smoothness of the film surface, the rubber particles are the sum of the (meth)acrylic resin constituting the (meth)acrylic resin film Quantity as a base Standardly, it is better to blend at a ratio of 3% by weight or more and 60% by weight or less, more preferably 45% by weight or less, and 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 becomes larger and the heat resistance decreases. 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 winding property during film formation may be poor, and the productivity may decrease. Furthermore, in the present invention, in the case of the rubber elastomer particles, when a layer exhibiting rubber elasticity and particles with a multilayer structure having other layers are used, the part composed of the layer exhibiting rubber elasticity and the layer inside The weight is taken as the weight of the rubber elastomer particles. For example, when the acrylic rubber elastomer particles with the above three-layer structure are used, the total weight of the acrylic rubber elastic polymer part of the middle layer and the hard polymer part mainly composed of methyl methacrylate in the innermost layer As the weight of rubber elastomer particles. When the acrylic rubber elastomer particles with the above three-layer structure are dissolved in acetone, the acrylic rubber elastic polymer part of the middle layer and the hard polymer part mainly composed of methyl methacrylate in the innermost layer remain as Insoluble content, so the total weight ratio of the middle layer and the innermost layer occupied by the three-layer acrylic rubber elastomer particles can be easily obtained.

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 mixed with the (meth)acrylic resin and rubber by melt kneading, etc. In addition to particles, it can also be obtained by first preparing rubber particles, and polymerizing the monomer composition used as the raw material of the (meth)acrylic resin in the presence of rubber particles.

、2,4-二苯基-6-(2-羥基-4-乙氧基苯基)-1,3,5-三

、2,4-二苯基-(2-羥基-4-丙氧基苯基)-1,3,5-三

、2,4-二苯基-(2-羥基-4-丁氧基苯基)-1,3,5-三

、2,4-二苯基-6-(2-羥基-4-丁氧基苯基)-1,3,5-三

、2,4-二苯基-6-(2-羥基-4-己基氧苯基)-1,3,5-三

、2,4-二苯基-6-(2-羥基-4-辛基氧苯基)-1,3,5-三

、2,4-二苯基-6-(2-羥基-4-十二碳基氧苯基)-1,3,5-三

、2,4-二苯基-6-(2-羥基-4-苯甲基氧苯基)-1,3,5-三

、2-(2-羥基-4-[1- 辛基氧羰基乙氧基]苯基)-4,6-雙(4-苯基苯基)-1,3,5-三

、4-雙[2-羥基-4-丁氧基苯基]-6-(2,4-二丁氧基苯基)-1,3,5-三

、2-[4-[(2-羥基-3-(2’-乙基)己基氧]-2-羥基苯基]-4,6-雙(2,4-二甲基苯基)-1,3,5-三

、2-(4,6-雙(2,4-二甲基苯基)-1,3,5-三

-2-基)-5-羥基苯基、2-[4,6-雙(2,4-二甲基苯基)-1,3,5-三

-2-基]-5-(辛基氧)酚、2-[2,6-二(2,4-二甲苯基)-1,3,5-三

-2-基]-5-辛基氧酚、2-(4,6-二苯基-1,3,5-三

-2-基)-5-[2-(2-乙基己醯基)乙氧基]酚、2,4,6-參(2-羥基-4-己基氧-3-甲氧基苯基)-1,3,5三

等三

系紫外線吸收劑等，亦可依需要而使用其等之2種以上。 The protective film may also contain usual additives, such as ultraviolet absorbers, organic dyes, pigments, inorganic pigments, antioxidants, antistatic agents, surfactants, etc. Among them, ultraviolet absorbers are more suitable for improving weather resistance. Examples of ultraviolet absorbers include 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl) )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-benzene Triazole, 2-(3,5-di-tertiary pentyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(2'-hydroxy-5'-tertiary octylphenyl) -2H-benzotriazole and other benzotriazole ultraviolet absorbers; 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2,4-di Hydroxybenzophenone, 2-hydroxy-4-methoxy-4'-chlorobenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy -4,4'-Dimethoxybenzophenone and other 2-hydroxybenzophenone UV absorbers; p-tertiary butyl phenyl salicylate, p-octyl phenyl salicylate Phenyl salicylate-based ultraviolet absorbers; 2,4-diphenyl-6-(2-hydroxy-4-methoxyphenyl)-1,3,5-tri

, 2,4-Diphenyl-6-(2-hydroxy-4-ethoxyphenyl)-1,3,5-tri

, 2,4-Diphenyl-(2-hydroxy-4-propoxyphenyl)-1,3,5-tri

, 2,4-Diphenyl-(2-hydroxy-4-butoxyphenyl)-1,3,5-tri

, 2,4-Diphenyl-6-(2-hydroxy-4-butoxyphenyl)-1,3,5-tri

, 2,4-Diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-tri

, 2,4-Diphenyl-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-tri

, 2,4-Diphenyl-6-(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-tri

, 2,4-Diphenyl-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-tri

, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-tri

, 4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-tri

, 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyloxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-three

, 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-tri

-2-yl)-5-hydroxyphenyl, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-tri

-2-yl]-5-(octyloxy)phenol, 2-[2,6-bis(2,4-xylenyl)-1,3,5-tri

-2-yl]-5-octyloxyphenol, 2-(4,6-diphenyl-1,3,5-tri

-2-yl)-5-[2-(2-ethylhexyl)ethoxy]phenol, 2,4,6-ginseng(2-hydroxy-4-hexyloxy-3-methoxyphenyl )-1,3,5

Wait three

It is an ultraviolet absorber, etc., and two or more of them may be used as needed.

系紫外線吸收劑、Chemipro化成股份有限公司製之「Kemisorb 102」(註冊商標)、ADEKA股份有限公司製之「Adekastab(註冊商標)LA46」、「Adekastab(註冊商標)LAF70」、BASF公司製之「TINUVIN(註冊商標)460」、「TINUVIN(註冊商標)405」、「TINUVIN(註冊商標)400」及「TINUVIN(註冊商標)477」、Sun-chemical股份有限公司製之「CYASORB(註冊商標)UV-1164」(以上，任一者皆為商品名)等。苯并三唑系紫外線吸收劑係可舉例如ADEKA股份有限公司製之「Adekastab LA31」及「Adekastab LA36」、住化Chemtex股份有限公司製之「Sumisorb(註冊商標)200」、「Sumisorb(註冊商標)250」、「Sumisorb(註冊商標)300」、「Sumisorb(註冊商標)340」及「Sumisorb(註冊商標)350」、Chemipro化成股份有限公司製之「Kemisorb 74」(註 冊商標)、「Kemisorb 79」(註冊商標)及「Kemisorb 279」(註冊商標)、BASF公司製之「TINUVIN(註冊商標)99-2」、「TINUVIN(註冊商標)900」及「TINUVIN(註冊商標)928」(以上，任一者皆為商品名)等。於(甲基)丙烯酸系樹脂膜含有紫外線吸收劑時，其量係相對於(甲基)丙烯酸系樹脂100重量%，通常為0.1重量%以上，較佳係0.3重量%以上，又更佳係3重量%以下。 UV absorbers can also use commercially available products, such as three

It is a UV absorber, "Kemisorb 102" (registered trademark) manufactured by Chemipro Chemical Co., Ltd., "Adekastab (registered trademark) LA46" manufactured by ADEKA Co., Ltd., "Adekastab (registered trademark) LAF70", "Adekastab (registered trademark) LAF70" manufactured by BASF Corporation TINUVIN (registered trademark) 460", "TINUVIN (registered trademark) 405", "TINUVIN (registered trademark) 400" and "TINUVIN (registered trademark) 477", "CYASORB (registered trademark) UV manufactured by Sun-chemical Co., Ltd. -1164" (any one of the above is a product name), etc. Benzotriazole-based ultraviolet absorbers include, for example, "Adekastab LA31" and "Adekastab LA36" manufactured by ADEKA Co., Ltd., "Sumisorb (registered trademark) 200" manufactured by Sumika Chemtex Co., Ltd., and "Sumisorb (registered trademark) )250", "Sumisorb (registered trademark) 300", "Sumisorb (registered trademark) 340" and "Sumisorb (registered trademark) 350", "Kemisorb 74" (registered trademark) manufactured by Chemipro Chemical Co., Ltd., and "Kemisorb 79 "(Registered trademark)" and "Kemisorb 279" (registered trademark), "TINUVIN (registered trademark) 99-2", "TINUVIN (registered trademark) 900" and "TINUVIN (registered trademark) 928" (above, Any one is a product name) etc. When the (meth)acrylic resin film contains an ultraviolet absorber, its amount is relative to 100% by weight of the (meth)acrylic resin, usually 0.1% by weight or more, preferably 0.3% by weight or more, and more preferably 3% by weight or less.

The production system of the (meth)acrylic resin film can adopt a conventionally known film production method. The (meth)acrylic resin film can also have a multi-layer structure, and the multi-layer structure of the (meth)acrylic resin film can use the method of the feed block, the method of using the multi-manifold die, etc., and the commonly known methods can be used Various methods. Among them, for example, by laminating through the feed block, multi-layer melt extrusion molding is performed from the T die, and at least one side of the resulting laminated film is brought into contact with a roller or a conveyor belt to form a film, a good surface texture can be obtained The point of the film is better. In particular, from the viewpoint of improving the surface smoothness and surface gloss of the (meth)acrylic resin film, it is preferable that both sides of the laminated film obtained by the above-mentioned multi-layer melt extrusion molding contact the surface of the roller or the surface of the conveyor belt. The method of filming. Among the rollers or conveyor belts used at this time, the surface of the roller or conveyor belt that is in contact with the (meth)acrylic resin is the one whose surface becomes a mirror surface in order to impart smoothness to the surface of the (meth)acrylic resin film Better.

The (meth)acrylic resin film system may be one that performs stretching treatment on the film produced in the above manner. In order to obtain a film with desired optical or mechanical properties, extension processing is necessary. Extension Processing Department Examples include uniaxial stretching or biaxial stretching. The stretching direction can include, for example, the mechanical flow direction (MD) of the unstretched film, the direction orthogonal to this (TD), and the direction oblique to the mechanical flow direction (MD). The two-axis extension system can be simultaneous two-axis extension while extending in two extension directions, or it can be a sequential two-axis extension that extends in a specific direction and then extends in other directions.

As long as the second protective film is included in the scope of the present invention, it may also be a protective film having optical functions such as a retardation film and a brightness enhancement film. For example, a transparent resin film composed of the above-mentioned material is stretched (uniaxially stretched or biaxially stretched, etc.), and a liquid crystal layer or the like is formed on the film, thereby forming a retardation film that gives an arbitrary retardation value.

The first protective film and the second protective film can form surface treatment layers (coating layers) such as a hard coat layer, an anti-glare layer, an anti-reflection layer, an antistatic layer, and an antifouling layer on the surface opposite to the polarizer. The method of forming the surface treatment layer on the surface of the protective film can use a known method.

The first protective film and the second protective film may be the same protective film or different protective films. Examples of when the protective film is different are: a combination of at least different types of thermoplastic resins constituting the protective film; a combination of whether or not the optical function of the protective film is at least different; a surface treatment layer formed on the surface The presence or absence or the combination of at least different in its kind.

The thickness of the first protective film and the second protective film is from the viewpoint of thinning of the polarizing plate, and the thinner is preferable. If it is too thin, the strength will decrease and the workability will be poor. 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, and even more preferably It is 50μm or less, particularly preferably 30μm or less.

(Adhesive)

The adhesive system that forms the first adhesive layer and the second adhesive layer can be appropriately selected from those known in the past. The polarizing plate does not peel off in a higher temperature environment, a humid environment, or a high and low temperature environment. Those who follow the sex are fine. Specifically, for example, acrylic adhesives, silicone adhesives, rubber adhesives, etc., are particularly preferred in terms of transparency, weather resistance, heat resistance, and processability. .

In addition, the same type of adhesive may be used for the first adhesive layer and the second adhesive layer, or different types of adhesives may be used.

In the adhesive system, fillers, pigments, colorants, fillers, antioxidants, ultraviolet rays, etc., composed of tackifiers, plasticizers, glass fibers, glass beads, metal powders, and other inorganic powders can be formulated according to needs. Various additives such as absorbents, antistatic agents, and silane coupling agents.

Usually the adhesive solution is applied to the release sheet and dried to form an adhesive layer. The coating system on the release sheet can adopt roll coating methods such as reverse coating, gravure coating, spin coating, screen coating, fountain coating, dipping, spraying, etc. The release sheet provided with the adhesive layer can be used by the transfer method. The thickness of the adhesive layer is usually about 3 to 100 μm, preferably 5 to 50 μm.

Preferably, the storage elastic modulus of the adhesive layer at 23° C. is 0.01 MPa to 1 MPa. When the storage elasticity of the adhesive layer is less than 0.01 MPa, the shrinkage of the polarizing plate during the high temperature test cannot be suppressed, and it is easy to produce The tendency to have poor appearance such as peeling. In addition, when the storage elastic modulus of the adhesive layer is greater than 1 MPa, the adhesive cannot alleviate the deformation between the glass and the polarizer during the thermal shock test, and there is a tendency for cracks to occur in the polarizer.

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

[Inspection method of polarizing plate]

The present invention further provides an inspection method of the polarizing plate. In the inspection method of the present invention, a first adhesive layer, a first protective film containing cellulose ester resin, a polarizer with a thickness of 10 μm or less, a second adhesive layer, and a second protective film are laminated, including : (1) The step of measuring the maximum size of the scar in the second protective film; (2) The maximum size of the scar in the second protective film is the opposite side to the second adhesive layer in the second protective film And at least one of the surfaces on the second adhesive layer side in the second protective film is 0.001 to 500 μm in length, 0.001 to 500 μm in width, and 0.001 to 10 μm in depth, and/or scratches in the second protective film The largest dimension of the second protective film is at least one of the surface on the opposite side to the second adhesive layer and the surface on the second adhesive layer side of the second protective film, and is a depth of 0.001 to A step of judging a polarizing plate of 10 μm and an area of 0.001 to 1.0 mm ² as good.

In the inspection method of the present invention, in step (1), the injury is measured The maximum size of the mark.

In step (1), the measurement of the maximum size of the polarizing plate that can have scars is performed by a common method, such as an electron microscope or a laser microscope.

Then, the step (2) includes: for the polarizing plate with the largest size measured in the step (1), the maximum size of the scar in the second protective film is on the opposite side of the second adhesive layer in the second protective film At least one of the surface of the second protective film and the surface of the second adhesive layer side is 0.001 to 500 μm in length, 0.001 to 500 μm in width, and 0.001 to 10 μm in depth, and/or

The maximum size of the scar in the second protective film is in at least one of the surface opposite to the second adhesive layer in the second protective film and the surface on the second adhesive layer side in the second protective film. A polarizing plate with a depth of 0.001 to 10 μm and an area of 0.001 to 1.0 mm ² is judged as a good product.

Here, when the maximum size of the scar in the second protective film is included in the above range, such a polarizing plate is judged to be a good product. In the inspection method of the present invention, the polarizing plate system judged to be a good product can be used without being discarded. In addition, the size of the scar may have the above-mentioned preferable range.

The polarizing plate selected as a good product in the aforementioned step (2) can be used for various optical applications. The polarizing plate selected as a good product in step (2) can be used in its original state, and further processing can also be performed as needed.

The polarizing plate obtained through such inspection steps can show good polarization characteristics without light leakage, cracks, etc. even under repeated high and low temperature environments. In addition, it can contribute to the thinning of the polarizer.

According to the inspection method of the polarizing plate of the present invention, for example, the polarizing plate after bonding the panel can also be inspected. When inspecting the polarizing plate after bonding the panel, for example, when bonding the panel, after bonding the panel, and when the backlight unit is bonded, the scars and dents that are generated during the bonding can be included in the scars of the present invention as long as they have a specific size.

The present invention can further obtain a liquid crystal panel obtained by bonding the polarizing plate of the present invention to a liquid crystal cell through an adhesive layer. In addition, the organic electroluminescence display device can be obtained by bonding the polarizing plate to the organic electroluminescence display through the adhesive layer.

[Example]

Hereinafter, examples are shown to describe the present invention more specifically, but the present invention is not limited to these examples. In the examples, the% and parts that indicate the content or usage amount are based on weight unless otherwise stated.

[Manufacturing of Polarizer]

A polyvinyl alcohol film with a thickness of 20μm (average degree of polymerization is about 2,400, saponification degree of 99.9 mol% or more) is uniaxially stretched to about 5 times by dry stretching, and the tension is directly maintained and immersed in pure water at 60°C1 Minutes later, it was immersed in an aqueous solution with a weight ratio of iodine/potassium iodide/water of 0.05/5/100 at 28°C for 60 seconds. Thereafter, it was immersed in an aqueous solution with a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 at 72°C for 300 seconds. Then, after washing with pure water at 26°C for 20 seconds, it was dried at 65°C to prepare a polarizer with a thickness of 7 μm with a polyvinyl alcohol film adsorbing iodine.

[First Adhesive Layer]

A commercially available adhesive sheet with a release treatment area layer of a polyethylene terephthalate film (release film) with a thickness of 38 μm and an acrylic adhesive layer with a thickness of 20 μm was used. No urethane acrylate oligomer is formulated in acrylic adhesives. The storage elastic modulus of the adhesive layer from which the release film was removed from the adhesive sheet was 0.05 MPa at 23°C and 0.04 MPa at 80°C.

[Second Adhesive Layer]

Add the organic solvent solution of urethane acrylate oligomer and isocyanate-based bridging agent to the copolymer of butyl acrylate and acrylic acid, and then apply the release treatment to the 38μm thick polyethylene terephthalate The release surface of the ester film (release film) is coated with a die slit coater to a thickness of 5μm after drying, and then dried to obtain an adhesive sheet laminated with an adhesive layer. The storage elastic modulus of the adhesive layer from which the release film was removed from the adhesive sheet was 0.40 MPa at 23°C and 0.18 MPa at 80°C.

[3rd Adhesive Layer]

Add an organic solvent solution of urethane acrylate oligomer and isocyanate-based bridging agent to the copolymer of butyl acrylate and acrylic acid, and then apply the release treatment to the 38μm thick polyethylene terephthalate The release surface of the ester film (release film) is coated with a die slit coater to a thickness of 5μm after drying, and then dried to obtain an adhesive sheet. The storage elastic modulus of the adhesive layer after removing the release film from the adhesive sheet is 0.40 MPa at 23°C. It is 0.18 MPa at 80°C.

[第1保护膜-1]

Triacetyl cellulose film manufactured by Konical Minolta Co., Ltd. (thickness 20μm, in-plane retardation value at a wavelength of 590nm = 1.2nm, retardation value in the thickness direction at a wavelength of 590nm = 1.3nm)

[第1保护膜-2]

A cycloolefin resin film (manufactured by ZEON Co., Ltd., Japan) having a thickness of 13 μm was used.

The in-plane retardation value (Re(590)) at a wavelength of 590nm (Re(590))=0.8nm, the retardation value in the thickness direction at a wavelength of 590nm (Rth(590))=3.4nm, the retardation value in the thickness direction at a wavelength of 483nm (Rth (483))=3.5nm, the retardation value in the thickness direction at a wavelength of 755nm (Rth(755))=2.8nm.

[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, dissolve 3 parts of carboxyl modified polyvinyl alcohol (KL-318 manufactured by Kuraray Co., Ltd.), and add water-soluble epoxy compound polyamide epoxy additives (Sumitomo Chemtex Sumirez resin (registered trademark) 650 (30), solid content 30% aqueous solution] 1.5 parts as water-based adhesive.

[Production of Polaroid Precursor A]

The first protective film-1 is laminated through the water-based adhesive on one side of the polarizer. After the lamination, it was dried at 80°C for 5 minutes to bond the first protective film and the polarizer. The bonding surface of the polarizer and the first protective film is the opposite side, and the second adhesive layer laminated on the release film is bonded. The bonding surface of the polarizer in the first protective film is the opposite side, and the first adhesive layer laminated on the release film is bonded.

In addition, they were attached so that the direction of the penetration axis of the polarizer and the width direction of the protective film became parallel.

In this way, a polarizing plate precursor A-1 in which a first adhesive layer, a protective film, a polarizer, and a second adhesive layer are sequentially laminated is produced.

In the same manner, the polarizing plate precursor made using the first protective film-2 is set as the polarizing plate precursor A-2. For other protective films, the polarizing plate precursor is made in the same way.

[Production of Polarizing Plate A]

Peel off the release film on the second adhesive layer in the polarizer precursor. The second adhesive layer in the polarizing plate precursor A and the brightness enhancement film are laminated to obtain a first adhesive layer, a first protective film, a polarizer, a second adhesive layer, and a brightness enhancement film (the first 2 protective film), the polarizing plate A. For example, a polarizing plate made using the first protective film-1 (polarizing plate precursor A-1) is set as the polarizing plate A1. Similarly, use the first protective film-2 (polarizing plate precursor A-2) The finished polarizing plate with such a structure is set as polarizing plate A2.

Cut the produced polarizer into 100mm×60mm. The peeling film on the first adhesive layer is peeled, and a polarizing plate is attached to alkali-free glass (made by Corning, EAGLE XG (registered trademark)) through the first adhesive layer. A scratch-type hardness tester (made by Erichsen, Germany, type 318 ball diameter 0.75mm) was used to apply a load of 5N to the surface of the polarizing plate from a distance of 1.0mm from the end of the polarizing plate to which the glass was laminated, giving a pressing scar . That is, the surface of the second protective film opposite to the second adhesive layer is provided with a pressing scratch. The depth of the scar is 2-5μm or less, and the diameter is 0.3mm (the area of the scar is about 0.071mm ² ).

In addition, samples were produced in which loads of 10N and 20N were applied to the surface of the polarizing plate by a scratch-type hardness tester at a distance of 1.0 mm from the end of another polarizing plate bonded to the glass. The depth of the scar made by applying a load of 10N is 5 to 8 μm, and the diameter is 0.4mm (the area of the scar is about 0.13mm ² ). The depth of the scar made by applying a load of 20N is 11 to 15 μm and the diameter is 0.6mm (the area of the scar is about 0.28mm ² ).

For the polarizing plate with a load of 5N, 10N, or 20N and a scratch on the surface, a cold and heat shock environmental test (250 cycles) at a temperature of 85°C and -40°C (each 30 minutes is a cycle) is performed.

[Cold and heat shock environmental test]

The thermal shock environmental test is based on the state where the polarizing plate is attached to the glass plate, using the thermal shock test device [product name "TSA-71L-A-3" sold by Espec Co., Ltd.], and high temperature conditions (85℃) ) Hold time 30 minutes and 30 minutes of holding time under low temperature conditions (-40°C) are performed as one cycle. In addition, the temperature movement time is set to 1 minute, and the temperature movement time at the time of temperature movement is 0 minutes, no outside air is introduced, and conditions are set to prevent condensation on the optical member. This cycle was repeated 250 cycles to implement the test. The judgment is as follows. The results are shown in Table 1.

[determination]

After conducting a thermal shock environment test (number of cycles: 250 times), visually confirm whether there is light leakage. Before the test, there was no change. After the test, the light leakage under the cross Nicol prism was marked as "○", and the light leakage under the cross Nicol prism after the test was marked as "×".

From this result, it can be seen that the polarizing plate of the present invention has an excellent effect in the thermal shock environmental test. That is, according to the present invention, even under repeated high and low temperature environments, the polarizing plate of the present invention does not cause light leakage, cracks, etc., and can show good polarization characteristics.

[Possibility of industrial use]

According to the present invention, even in the repeated high temperature and low temperature Under the environment, the polarizing plate of the present invention does not cause light leakage, cracks, etc., and can show good polarization characteristics. In addition, the polarizing plate of the present invention is thin and has excellent strength and durability.

11‧‧‧Polarizer

12‧‧‧The first protective film

13‧‧‧The first adhesive layer

22‧‧‧Second protective film

23‧‧‧Second adhesive layer

100‧‧‧Polarizer

Claims (4)

A polarizing plate which is laminated in sequence: a first adhesive layer, a first protective film containing cellulose ester resin, a polarizer with a thickness of 10 μm or less, a second adhesive layer, and a second protective film, wherein The first protective film and the polarizer are laminated through the aqueous adhesive layer, and the absolute value of the difference between the dimensional change rate (85°C) and the dimensional change rate (30°C) of the first protective film is 0.00 to 0.50, The second protective film has a scratch on at least one of the surface of the second protective film opposite to the second adhesive layer and the surface of the second protective film on the second adhesive layer side, The aforementioned scar is at least one of a length of 0.001 to 500 μm, a width of 0.001 to 500 μm, and a depth of 0.001 to 10 μm, and a depth of 0.001 to 10 μm and an area of 0.001 to 1.0 mm ² . The polarizing plate described in claim 1, wherein the second protective film has a flaw on the surface of the second protective film opposite to the second adhesive layer. The polarizing plate described in item 1 or 2 of the scope of patent application, wherein the aforementioned second protective film is a brightness enhancement film. A method for inspecting a polarizing plate, the polarizing plate is laminated with: a first adhesive layer, a first protective film containing cellulose ester resin, a polarizer with a thickness of 10 μm or less, a second adhesive layer, and a second protective film For film, it includes the following steps: (1) the step of measuring the maximum size of the scar in the second protective film; (2) the maximum size of the scar in the second protective film and the sum of the maximum size of the scar in the second protective film At least one of the surface on the opposite side of the second adhesive layer and the surface on the side of the second adhesive layer in the second protective film has a length of 0.001 to 500 μm, a width of 0.001 to 500 μm, and a depth of 0.001 to 10 μm The polarizing plate and/or the maximum size of the scar in the second protective film is on the side opposite to the second adhesive layer in the second protective film and the second adhesive in the second protective film In at least one of the surfaces on the side of the agent layer, a polarizing plate having a depth of 0.001 to 10 μm and an area of 0.001 to 1.0 mm ² is judged as a good product.

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