JP2020160461A - Flexible polarizing film, manufacturing method therefor, and image display device - Google Patents

Abstract

To provide a flexible polarizing film which employs a polyvinyl alcohol-based polarizer and yet offers superior flexibility.SOLUTION: A flexible polarizing film of the present invention comprises a polyvinyl alcohol-based polarizer containing a polyvinyl alcohol-based resin aligned in one direction and iodine or dichroic pigment adsorbed and aligned in the polyvinyl alcohol-based resin, and having a thickness of 10 μm or less, and does not exhibit cracks, creases, and light leakage in either direction after going through a U-shape flexing test involving repetitive flexing of the film into a U-shape in an alignment direction of the polyvinyl alcohol-based resin and in a direction perpendicular to the alignment direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a flexible polarizing film and a method for producing the same. The flexible polarizing film can form an image display device such as a liquid crystal display device (LCD) or an organic EL display device alone or as an optical film obtained by laminating the flexible polarizing film.

In a liquid crystal display device, it is indispensable to arrange polarizers on both sides of a glass substrate forming a liquid crystal panel surface according to the image forming method. As the polarizer, a polyvinyl alcohol-based polarizer in which a polyvinyl alcohol-based resin is generally oriented in one direction and iodine or a dichroic dye is adsorbed or oriented on the polyvinyl alcohol-based resin is used. .. However, the polyvinyl alcohol-based polarizer has a problem that it is brittle and easily torn by itself. In particular, the polyvinyl alcohol-based polarizer is likely to tear in parallel with the direction in which the polyvinyl alcohol-based resin is oriented (absorption axis direction), and for example, when an external force that causes contraction in the absorption axis direction is applied, the polyvinyl alcohol-based polarizing element is easily torn. ..

Therefore, the polyvinyl alcohol-based polarizing element is generally used as a polarizing film in which a transparent protective film is attached to one side or both sides thereof.

As other polarizers, in addition to polyvinyl alcohol-based polarizers, grid polarizers are known (Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2005-316495 JP-A-2007-232792

However, a general polarizing film using a polyvinyl alcohol-based polarizing element has rigidity (stiffness) because a transparent protective film is bonded to the polarizing film, and lacks flexibility (flexibility). Therefore, when the polarizing film is twisted, the entire film may be cracked, broken marks (break marks) may remain, or light may escape from the polarizing element. It was constrained. On the other hand, the grid polarizer has flexibility but lacks versatility.

An object of the present invention is to provide a flexible polarizing film having a high degree of flexibility and a method for producing the same, despite the use of a polyvinyl alcohol-based polarizer.

Another object of the present invention is to provide an image display device having the flexible polarizing film.

As a result of diligent studies, the inventors of the present application have found that the above problems can be solved by the following flexible polarizing film and the like, and have reached the present invention.

That is, the present invention has a polyvinyl alcohol-based polarizer having a thickness of 10 μm or less in which the polyvinyl alcohol-based resin is oriented in one direction and iodine or a dichroic dye is adsorbed and oriented on the polyvinyl alcohol-based resin. After performing a U-shaped expansion and contraction test that repeats expansion and contraction in a U-shape in the orientation direction in which the polyvinyl alcohol-based resin is oriented and in the direction orthogonal to the orientation direction, cracks, creases, and light leakage occur in either direction. With respect to a flexible polarizing film, which is characterized by the absence of.

It is preferable that the flexible polarizing film has no cracks, creases, or light escape after being subjected to a twisting test in which the polyvinyl alcohol-based resin is twisted in the orientation direction.

After the flexible polarizing film is subjected to a bending holding test in which the polyvinyl alcohol-based resin is bent and held in the orientation direction in which the polyvinyl alcohol-based resin is oriented and in a direction orthogonal to the orientation direction, the bent shape is maintained in either direction. At the same time, it is preferable that cracks do not occur.

In the flexible polarizing film, in the flexibility test in the orientation direction in which the polyvinyl alcohol-based resin is oriented and in the direction orthogonal to the orientation direction, the rigidity (mm) is preferably 60 mm or less.

In the flexible polarizing film, it is preferable that the tensile strength in the direction orthogonal to the orientation direction in which the polyvinyl alcohol-based resin is oriented in the tensile test is 5 N / 10 mm or more.

In the flexible polarizing film, the polyvinyl alcohol-based polarizer has an optical characteristic represented by a simple substance transmittance T and a degree of polarization P of the following formula P>-(10 ^{0.929T-42.4-1} ) × 100 ( However, T <42.3) or
It is preferable that the structure is configured to satisfy the condition of P ≧ 99.9 (however, T ≧ 42.3).

In the flexible polarizing film, it is preferable to have reinforcing films in close contact with the polyvinyl alcohol-based polarizer on both sides of the polyvinyl alcohol-based polarizer. It is preferable that the thickness of the reinforcing film on at least one side is 15 μm or less.

In the flexible polarizing film, it is preferable that the first one side of the polyvinyl alcohol-based polarizing element has a first reinforcing film having a thickness of 15 μm or less, and the other second side has a second reinforcing film having a thickness of 15 μm or less. .. The thickness difference between the first reinforcing film and the second reinforcing film is preferably 10 μm or less.

In the flexible polarizing film, the ratio of the thickness of the reinforcing film to the thickness of the polyvinyl alcohol-based polarizer is preferably 0.4 or more.

In the flexible polarizing film, the reinforcing film preferably has a compressive elastic modulus of 1 MPa or more at 23 ° C.

In the flexible polarizing film, the reinforcing film may be one that is not substantially oriented.

In the flexible polarizing film, a resin film can be used as the reinforcing film. The resin film is preferably a product of a thermosetting resin or an active energy ray-curable resin.

Further, the present invention is a method for manufacturing the flexible polarizing film.
Step (1) of preparing a polyvinyl alcohol-based polarizer having a thickness of 10 μm or less, in which the polyvinyl alcohol-based resin is oriented in one direction and iodine or a dichroic dye is adsorbed and oriented on the polyvinyl alcohol-based resin.
A reinforcing film is formed by applying a liquid material containing a resin component or a curable component capable of forming a resin film on both sides of the polyvinyl alcohol-based polarizer, and then solidifying or curing the liquid material. The present invention relates to a method for producing a flexible polarizing film, which comprises a step (2) of forming.

The present invention also relates to an image display device having the flexible polarizing film.

The flexible polarizing film of the present invention uses a polyvinyl alcohol-based polarizer, and can satisfy versatility. Further, the polyvinyl alcohol-based polarizer is suitable in that the thickness is 10 μm or less and the thickness is reduced.

Further, the flexible polarizing film of the present invention has a high degree of flexibility despite the fact that it uses a polyvinyl alcohol-based polarizer that is brittle and easily torn by itself, and is deformed into a shape by twisting. Even in this case, cracks do not occur in the entire film, break marks (break marks) remain, and light leakage does not occur in the polarizer. Further, the flexible polarizing film of the present invention can have flexibility against various deformations such as expansion and contraction and bending. As described above, in the flexible polarizing film of the present invention, the polarizing film itself has flexibility, and the tensile breaking stress becomes remarkably small when a normal polyvinyl alcohol-based polarizer is used alone, and it is practically impossible to handle. On the other hand, it is thin and easy to handle.

In addition, the flexible polarizing film of the present invention has flexibility even when it is used in combination with other members or in combination with other members by taking advantage of its flexibility, and it is possible to suppress cracks in the polarizer. Yes, it can be used for various purposes. Therefore, the applications of the flexible polarizing film alone will be greatly expanded due to the expansion of the applications and the expansion of the tolerance during the process. Therefore, the flexible polarizing film of the present invention can be used as an alternative to the polarizing element, for example, in a design that cannot be applied due to brittleness and easiness of tearing in the conventional polarizer, and the polarizing film (transparent protection to the polarizer). As an alternative to the one provided with a film), for example, it is possible to deal with various deformed shapes that could not be applied due to the rigidity of the conventional polarizing film, and it is possible to expand the application development.

This is an example of a schematic cross-sectional view of the flexible polarizing film of the present invention. It is the schematic which shows the state of the U shape in the U shape expansion and contraction test. It is a schematic diagram which shows the state of twisting in a twisting test. It is the schematic which shows the state of bending in the bending holding test. It is the schematic which shows the stiffness in a stiffness test. It is the schematic which shows the tensile test.

The flexible polarizing film of the present invention will be described below. The flexible polarizing film of the present invention has a polyvinyl alcohol-based polarizer.

<Polyvinyl alcohol-based polarizer>
In the polyvinyl alcohol-based polarizer, the polyvinyl alcohol-based resin is oriented in one direction (absorption axis direction), and iodine or a dichroic dye is adsorbed or oriented on the polyvinyl alcohol-based resin. Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol, partially formalized polyvinyl alcohol, ethylene-vinyl acetate copolymer system partially saponified product, and the like. The polarizer can be obtained by adsorbing a dichroic dye such as iodine or a dichroic dye on a polyvinyl alcohol film using the polyvinyl alcohol resin and uniaxially stretching the film.

A uniaxially stretched polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine or a dichroic dye is produced by, for example, dyeing by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching it to 3 to 7 times the original length. can do. If necessary, boric acid, zinc sulfate, zinc chloride and the like may be contained, or the mixture may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. In addition to being able to clean the surface of the polyvinyl alcohol film and blocking inhibitors by washing the polyvinyl alcohol film with water, it also has the effect of preventing non-uniformity such as uneven dyeing by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine or a dichroic dye, stretching while dyeing, or stretching and then dyeing with iodine or a dichroic dye. It can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

It is preferable that the polyvinyl alcohol-based polarizer contains boric acid from the viewpoint of stretch stability and optical durability. Further, the boric acid content contained in the polarizer is preferably 25% by weight or less, more preferably 20% by weight or less, based on the total amount of the polarizer, from the viewpoint of suppressing the occurrence of light leakage. Further, it is preferably 18% by weight or less, more preferably 16% by weight or less. On the other hand, from the viewpoint of stretching stability and optical durability of the polarizer, the boric acid content with respect to the total amount of the polarizer is preferably 10% by weight or more, more preferably 12% by weight or more.

In the present invention, a polyvinyl alcohol-based polarizer having a thickness of 10 μm or less is used. When the thickness of the polyvinyl alcohol-based polarizer exceeds 10 μm, it is difficult to obtain sufficient flexibility. The thickness of the polarizer is preferably 8 μm or less, more preferably 7 μm or less, and further preferably 6 μm or less from the viewpoint of thinning and flexibility. On the other hand, the thickness of the polarizer is preferably 2 μm or more, more preferably 3 μm or more. Such a thin polarizing element has less uneven thickness, excellent visibility, and less dimensional change, so that it has excellent durability against thermal shock.

As a thin polarizer, typically
Japanese Patent No. 4751486,
Japanese Patent No. 4751481
Patent No. 4815544,
Japanese Patent No. 5048120,
International Publication No. 2014/07759 Pamphlet,
International Publication No. 2014/077636 Pamphlet,
Etc., or the thin polarizing element obtained from the manufacturing method described in these.

The polarizer has optical characteristics represented by a simple substance transmittance T and a degree of polarization P of the following equation P> − (10 ^0.929 T ^-42.4 -1) × 100 (where T <42.3). Or,
It is configured to satisfy the condition of P ≧ 99.9 (however, T ≧ 42.3). A polarizer configured to satisfy the above conditions primarily has the performance required for a display for a liquid crystal television using a large display element. Specifically, the contrast ratio is 1000: 1 or more and the maximum brightness is 500 cd / m ² or more. As another application, for example, it is bonded to the visual side of an organic EL display device.

On the other hand, a polarizer configured to satisfy the above conditions has a thickness of 10 μm or less because the constituent polymer (for example, a polyvinyl alcohol-based molecule) exhibits high orientation. The tensile breaking stress in the direction orthogonal to the absorption axis direction (transmission axis direction) is significantly reduced. As a result, for example, in a general polarizing film, there is an extremely high possibility that light leakage occurs in the absorption axis direction of the polarizer. The flexible polarizing film of the present invention has excellent flexibility even though it uses a polyvinyl alcohol-based polarizing element having a thickness of 10 μm or less and is weak against impact.

The thin polarizer is patented in Patent No. 4751486, in that it can be stretched at a high magnification and the polarization performance can be improved even in a manufacturing method including a step of stretching in a laminated state and a step of dyeing. Those obtained by a production method including a step of stretching in an aqueous boric acid solution as described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544 are preferable, and particularly described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544. It is preferably obtained by a production method including a step of auxiliary stretching in the air before stretching in a certain boric acid aqueous solution. These thin polarizers can be obtained by a production method including a step of stretching a polyvinyl alcohol-based resin (hereinafter, also referred to as PVA-based resin) layer and a resin base material for stretching in a laminated state and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching because it is supported by the stretching resin base material.

Further, the flexible polarizing film of the present invention is characterized in that, specifically, after performing the U-shaped expansion / contraction test shown in the examples, there is no cracking, creases, and light leakage. The U-shaped expansion / contraction test is an index showing flexibility related to bendability in a U-shape with no load in the orientation direction (absorption axis direction) in which the polyvinyl alcohol resin is oriented and in the orthogonal direction (transmission axis direction). .. The flexible polarizing film of the present invention has excellent bendability with no load in both the absorption axis direction and the transmission axis direction by suppressing the occurrence of cracks, creases and light leakage in the U-shaped expansion and contraction test. It turns out that it has the flexibility to be involved.

Specifically, it is preferable that the flexible polarizing film of the present invention can suppress cracks in the polyvinyl alcohol-based polarizing element, generation of creases, and light loss after the twisting test shown in the examples. The twist test is an index showing flexibility in a twisted state in the orientation direction (absorption axis direction) in which a polyvinyl alcohol-based resin, which is prone to cracking, creases, and light leakage, is oriented. In the twisting test, the flexible polarizing film of the present invention is found to have excellent flexibility in a twisted state without cracking, creases, and light leakage.

Further, it is preferable that the flexible polarizing film of the present invention retains its bent shape and suppresses cracking after the bending holding test shown in the examples. In the bending retention test, the flexible polarizing film maintains its original state even when it is bent and bent in the orientation direction (absorption axis direction) in which the polyvinyl alcohol resin is oriented and in the orthogonal direction (transmission axis direction). It is an index showing the flexibility related to the retention that can be performed. It can be seen that the flexible polarizing film of the present invention has excellent retention in both the absorption axis direction and the transmission axis direction by retaining the bent shape and suppressing cracking in the bending holding test.

Further, it is preferable that the flexible polarizing film of the present invention satisfies the rigidity (mm) of 60 mm or less in the rigidity test shown in the examples. The rigidity test is an index showing flexibility related to bending followability (low resistance to bending) in the orientation direction (absorption axis direction) in which the polyvinyl alcohol resin is oriented and in the orthogonal direction (transmission axis direction). It can be seen that the flexible polarizing film of the present invention has the rigidity and softness of 60 mm or less, and has flexibility related to bending followability (low resistance to bending). It is an index showing the flexibility of the rigidity (mm), and is preferably 50 mm or less, more preferably 40 mm or less. On the other hand, there is no particular limitation on the lower limit of the rigidity (mm).

Further, the flexible polarizing film of the present invention preferably satisfies a tensile strength of 5 N / 10 mm or more in a tensile test shown in Examples. The tensile test is an index showing the strength in the direction orthogonal to the orientation direction (absorption axis direction) in which the polyvinyl alcohol-based resin is oriented (transmission axis direction). It can be seen that the flexible polarizing film of the present invention has strength in the transmission axis direction when the tensile strength satisfies 5N / 10 mm or more. From the viewpoint of strength, the tensile strength is preferably 7 N / 10 mm or more, and more preferably 10 N / 10 mm or more.

An example of the flexible polarizing film of the present invention will be described below with reference to FIG.
As the flexible polarizing film of the present invention, for example, one having reinforcing films on both sides of a polyvinyl alcohol-based polarizer can be used. The flexible polarizing film 1 of FIG. 1 has a first reinforcing film b1 on the first side of the polyvinyl alcohol-based polarizing element 1 and a second reinforcing film b2 on the other second side. In the flexible polarizing film 1 of the present invention, the first reinforcing film b1 and the second reinforcing film b2 are directly provided on the polyvinyl alcohol-based polarizing element 1.

The flexible polarizing film 1 of the present invention has flexibility in the U-shaped expansion / contraction test, and has a transparent protective film or the like on one side or both sides of the polyvinyl alcohol-based polarizing element a to satisfy the flexibility. It is clearly distinguished from ordinary polarizing films that cannot be used.

<Reinforcing membrane>
The thickness of the reinforcing film is preferably 15 μm or less, more preferably 10 μm or less, and further preferably 7 μm or less from the viewpoint of thinning and flexibility. On the other hand, the thickness of the reinforcing film is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 5 μm or more from the viewpoint of flexibility and strength.

Further, the ratio (t2 / t1) of the thickness (t2) of the reinforcing film to the thickness (t1) of the polyvinyl alcohol-based polarizer is preferably 0.4 or more from the viewpoint of flexibility and strength, and further 0. It is preferably 6.6 or more, and more preferably 0.8 or more. On the other hand, the ratio (t2 / t1) is preferably 2.0 or less, more preferably 1.5 or less, and further preferably 1.2 or less from the viewpoint of thinning. preferable.

When the reinforcing film has the first reinforcing film b1 and the second reinforcing film b2 on both sides of the polyvinyl alcohol-based polarizer 1, the U-shaped expansion / contraction test and the twisting test are performed as compared with the case where the reinforcing film is provided on only one side. It is preferable from the viewpoint that the flexibility in the above can be more satisfied and the strength in the tensile test can be satisfied.

The thickness of each reinforcing film of the first reinforcing film b1 and the second reinforcing film b2 on both sides of the polyvinyl alcohol-based polarizer 1 may be the same or different, but the first reinforcing film b1 and the second reinforcing film b1 The difference in the thickness of b2 makes the stress in the flexible polarizing film uniform (symmetrical) in the normal state (state where only the flexible polarizing film is left unattended) and the flexibility test (various tests such as the U-shaped expansion and contraction test). The thickness is preferably 10 μm or less, more preferably 7 μm or less, further preferably 5 μm or less, and particularly preferably the same thickness, because it is easy to secure strength and flexibility.

The reinforcing film preferably has a compressive elastic modulus at 23 ° C. of 1 MPa or more from the viewpoint of strength. Further, the compressive elastic modulus of the reinforcing film is preferably 10 MPa or more, and more preferably 100 MPa or more. On the other hand, when the compressive elastic modulus of the reinforcing film layer becomes large, it tends to become too hard and the flexibility tends to deteriorate. Therefore, the compressive elastic modulus is preferably 10 GPa or less, and more preferably 1 GPa or less.

The reinforcing film can be formed from various forming materials. The reinforcing film can be formed, for example, by applying a resin material to a polyvinyl alcohol-based polarizer, or by depositing an inorganic oxide such as SiO ₂ on a polyvinyl alcohol-based polarizer by a sputtering method or the like. You can also do it. The reinforcing film is preferably a resin film formed from a resin material from the viewpoint of easy formation.

The reinforcing film may or may not be oriented, and either of them can be used. If the reinforcing film is oriented, a phase difference will occur and the optical characteristics of the polyvinyl alcohol-based polarizer will change. Therefore, when maintaining the optical characteristics of the polarizer, the reinforcing film is not substantially oriented. Is preferable. The term "substantially not oriented" means a state in which the reinforcing film is not positively oriented even though the reinforcing film is oriented due to the orientation of the polarizer. The reinforcing film that is not practically oriented can be formed, for example, by applying a resin film forming material to a polyvinyl alcohol-based polarizer. On the other hand, as the reinforcing film, an oriented one can be used. The oriented reinforcing film exhibits a phase difference and can also be used as an optical compensation film or the like.

The material for forming the reinforcing film is not particularly limited as long as it is a material capable of adhering to a polyvinyl alcohol-based polarizer, and for example, a polyester resin, a polyether resin, a polycarbonate resin, a polyurethane resin, or a silicone resin. Examples thereof include resins, polyamide-based resins, polyimide-based resins, PVA-based resins, acrylic-based resins, and epoxy-based resins. One of these resin materials can be used alone or in combination of two or more, and among these, one or more selected from the group consisting of polyurethane resin, PVA resin, acrylic resin, and epoxy resin. Is preferable, and polyurethane-based resins and acrylic-based resins are more preferable.

The reinforcing film is formed by applying a liquid material containing the surface of the polarizer, the resin component or a curable component capable of forming the resin, and then solidifying or curing the liquid material. Can be done. The form of the coating liquid, which is a liquid substance, is not particularly limited as long as it is liquid, and may be water-based, water-dispersed, solvent-based, or solvent-free.

The forming material may contain an additive as long as the function of the reinforcing film is not impaired. For example, silane coupling agents, polyether compounds of polyalkylene glycols such as polypropylene glycol, powders such as colorants and pigments, dyes, surfactants, plasticizers, tackifiers, antistatic agents, surface lubricants, etc. Depending on the application using leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particulates, foils, etc. It can be added as appropriate. Further, a redox system to which a reducing agent is added may be adopted within a controllable range.

It is advantageous that the liquid material (coating liquid) has a low viscosity. The viscosity measured at 25 ° C. is preferably 2000 mPa · s or less, more preferably 1000 mPa · s or less, further preferably 500 mPa · s or less, and further 100 mPa · s. It is preferably as follows.

In forming the reinforcing film, after applying a liquid material containing the resin component, the resin component is solidified according to the type. The liquid substance containing the resin component is a solution in which the resin component is dissolved or dispersed in a solvent, and is used as, for example, an aqueous solution, an aqueous dispersion-based dispersion, or a solvent-based solution. The solidification means forming a resin layer by removing a solvent from the liquid material.

An aqueous resin emulsion can be used as the dispersion liquid of the aqueous dispersion system. The aqueous resin emulsion contains emulsion resin particles emulsified in water (dispersion medium). The reinforcing film of the present invention can be formed by directly applying a forming material containing the aqueous resin emulsion to a polarizer and drying it.

The resin constituting the emulsion resin is not particularly limited, and examples thereof include acrylic resin, silicone resin, polyurethane resin, and fluorine resin. Among these, polyurethane resins and acrylic resins are preferable in the present invention because they are excellent in optical transparency, weather resistance, heat resistance, and the like.

Examples of the water-based resin emulsion include trade names: SE-2915E (acrylic emulsion containing UV absorber) manufactured by Taisei Fine Chemical Co., Ltd., trade names: Aron A-104, Aron A-106, etc. manufactured by Toagosei Co., Ltd. Be done.

On the other hand, in forming the transparent resin layer, after applying a liquid substance containing a curable component capable of forming the resin, the curable component forms the resin according to the type of the curable component. Can be cured. The liquid material containing a curable component that can form the resin can be used in a solvent-free system as long as the curable component exhibits a liquid material. Further, as the liquid substance, a solution in which the curable component is dissolved in a solvent can be used. It can also be used as a solution when the curable component presents a liquid substance. The solvent can be appropriately selected depending on the curable component used. For example, when an acrylic monomer forming an acrylic resin is used as the curable component, or when an epoxy monomer forming an epoxy resin is used, the liquid material containing the curable component is irradiated with active energy rays (ultraviolet rays). It can be cured by irradiation) or the like.

The reinforcing film will be described with respect to a curable forming material containing a curable component capable of forming a resin. The curable component can be roughly classified into an active energy ray-curable type such as an electron beam curable type, an ultraviolet curable type, and a visible light curable type, and a thermosetting type. Further, the ultraviolet curable type and the visible light curable type can be classified into a radical polymerization curable type and a cationic polymerization curable type. In the present invention, active energy rays having a wavelength range of 10 nm to less than 380 nm are referred to as ultraviolet rays, and active energy rays having a wavelength range of 380 nm to 800 nm are referred to as visible light. The radical polymerization curing type curable component can be used as a thermosetting type curable component.

≪Radical polymerization curing type forming material≫
Examples of the curable component include radically polymerizable compounds. Examples of the radically polymerizable compound include compounds having a radically polymerizable functional group of a carbon-carbon double bond such as a (meth) acryloyl group and a vinyl group. As these curable components, either a monofunctional radical polymerizable compound or a bifunctional or higher polyfunctional radical polymerizable compound can be used. In addition, these radically polymerizable compounds may be used alone or in combination of two or more. As these radically polymerizable compounds, for example, compounds having a (meth) acryloyl group are suitable. In addition, in this invention, (meth) acryloyl means acryloyl group and / or methacryloyl group, and "(meth)" has the same meaning below.

≪Monofunctional radical polymerizable compound≫
Examples of the monofunctional radically polymerizable compound include (meth) acrylamide derivatives having a (meth) acrylamide group. The (meth) acrylamide derivative is preferable in terms of ensuring adhesion to the polarizer and in terms of high polymerization rate and excellent productivity. Specific examples of the (meth) acrylamide derivative include N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, and N. N-alkyl group-containing (meth) acrylamide derivatives such as -butyl (meth) acrylamide, N-hexyl (meth) acrylamide; N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-methylol-N- N-Hydroxyalkyl group-containing (meth) acrylamide derivatives such as propane (meth) acrylamide; N-aminoalkyl group-containing (meth) acrylamide derivatives such as aminomethyl (meth) acrylamide and aminoethyl (meth) acrylamide; N-methoxymethyl N-alkoxy group-containing (meth) acrylamide derivatives such as acrylamide and N-ethoxymethylacrylamide; N-mercaptoalkyl group-containing (meth) acrylamide derivatives such as mercaptomethyl (meth) acrylamide and mercaptoethyl (meth) acrylamide; Be done. Examples of the heterocyclic (meth) acrylamide derivative in which the nitrogen atom of the (meth) acrylamide group forms a heterocycle include N-acrylloylmorpholine, N-acrylloylpiperidin, N-methacryloylpiperidin, and N-acrylloylpyrrolidine. And so on.

Among the (meth) acrylamide derivatives, an N-hydroxyalkyl group-containing (meth) acrylamide derivative is preferable, and N-hydroxyethyl (meth) acrylamide is particularly preferable, from the viewpoint of adhesion to a polarizer.

In addition, examples of the monofunctional radically polymerizable compound include various (meth) acrylic acid derivatives having a (meth) acryloyloxy group. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl ( Meta) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, t-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2,2-Dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl ( Examples thereof include (meth) acrylic acid (1-20 carbon atoms) alkyl esters such as meta) acrylate and n-octadecyl (meth) acrylate.

Further, as the (meth) acrylic acid derivative, for example, cycloalkyl (meth) acrylate such as cyclohexyl (meth) acrylate and cyclopentyl (meth) acrylate;
Aralkyl (meth) acrylates such as benzyl (meth) acrylate;
2-Isobornyl (meth) acrylate, 2-norbornylmethyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornylmethyl (meth) acrylate, dicyclo Polycyclic (meth) acrylates such as pentenyl (meth) acrylicate, dicyclopentenyloxyethyl (meth) acrylicate, dicyclopentanyl (meth) acrylicate, etc.;
2-Methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) Alkoxy groups such as acrylate and alkylphenoxy polyethylene glycol (meth) acrylate or phenoxy group-containing (meth) acrylate; and the like can be mentioned.

Examples of the (meth) acrylic acid derivative include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-. Hydroxyalkyl (meth) acrylates such as hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate Or, hydroxyl group-containing (meth) acrylates such as [4- (hydroxymethyl) cyclohexyl] methyl acrylate, cyclohexanedimethanol mono (meth) acrylate, and 2-hydroxy-3-phenoxypropyl (meth) acrylate;
Epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether;
2,2,2-Trifluoroethyl (meth) acrylate, 2,2,2-trifluoroethyl ethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) ) Halogen-containing (meth) acrylates such as acrylates, heptadecafluorodecyl (meth) acrylates, 3-chloro-2-hydroxypropyl (meth) acrylates;
Alkylaminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate;
3-Oxetanylmethyl (meth) acrylate, 3-methyl-oxetanylmethyl (meth) acrylate, 3-ethyl-oxetanylmethyl (meth) acrylate, 3-butyl-oxetanylmethyl (meth) acrylate, 3-hexyluoxetanylmethyl (meth) ) Oxetane group-containing (meth) acrylate such as acrylate;
(Meta) acrylates having a heterocycle such as tetrahydrofurfuryl (meth) acrylate and butyrolactone (meth) acrylate, neopentyl glycol (meth) acrylic acid adduct of hydroxypivalate, p-phenylphenol (meth) acrylate, etc. Can be mentioned.

Examples of the monofunctional radically polymerizable compound include carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

Examples of the monofunctional radically polymerizable compound include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazin, and vinylpyrazine. Examples thereof include vinyl-based monomers having a nitrogen-containing heterocycle such as vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholin.

Further, as the monofunctional radically polymerizable compound, a radically polymerizable compound having an active methylene group can be used. A radically polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth) acrylic group at the terminal or in the molecule and having an active methylene group. Examples of the active methylene group include an acetoacetyl group, an alkoxymalonyl group, a cyanoacetyl group and the like. It is preferable that the active methylene group is an acetoacetyl group. Specific examples of the radically polymerizable compound having an active methylene group include 2-acetoacetoxyethyl (meth) acrylate, 2-acetoacetoxypropyl (meth) acrylate, 2-acetacetoxy-1-methylethyl (meth) acrylate and the like. Acetacetoxyalkyl (meth) acrylate; 2-ethoxymalonyloxyethyl (meth) acrylate, 2-cyanoacetoxyethyl (meth) acrylate, N- (2-cyanoacetoxyethyl) acrylamide, N- (2-propionylacetoxybutyl) Examples thereof include acrylamide, N- (4-acetoacetoxymethylbenzyl) acrylamide, and N- (2-acetoacetylaminoethyl) acrylamide. The radically polymerizable compound having an active methylene group is preferably acetoacetoxyalkyl (meth) acrylate.

≪Multifunctional radical polymerizable compound≫
Examples of the bifunctional or higher polyfunctional radical polymerizable compound include tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and 1,9. -Nonandiol di (meth) acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di (meth) acrylate, bisphenol A di (meth) acrylate, bisphenol A ethylene oxide adduct di (meth) ) Acrylate, bisphenol A propylene oxide adduct di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, neopentyl glycol di (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, cyclic tri Methylolpropanformal (meth) acrylate, dioxane glycol di (meth) acrylate, trimethylpropantri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate , Dipentaerythritol hexa (meth) acrylate, esterified product of (meth) acrylic acid such as EO-modified diglycerin tetra (meth) acrylate and polyhydric alcohol, 9,9-bis [4- (2- (meth) acryloyl) Oxyethoxy) phenyl] Fluorene can be mentioned. Specific examples include Aronix M-220, M-306 (manufactured by Toagosei Co., Ltd.), Light Acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), Light Acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), Light Acrylate DCP- Examples thereof include A (manufactured by Kyoeisha Chemical Co., Ltd.), SR-531 (manufactured by Sartomer), and CD-536 (manufactured by Sartomer). Further, if necessary, various epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, various (meth) acrylate-based monomers and the like can be mentioned.

As the radically polymerizable compound, it is preferable to use a monofunctional radically polymerizable compound and a polyfunctional radically polymerizable compound in combination from the viewpoint of achieving both adhesion to a polarizer and optical durability. Usually, it is preferable to use the monofunctional radical polymerizable compound in an amount of 3 to 80% by weight and the polyfunctional radical polymerizable compound in an amount of 20 to 97% by weight based on 100% by weight of the radically polymerizable compound.

<< Aspects of radical polymerization curing type forming material >>
The radical polymerization curing type forming material can be used as an active energy ray curing type or thermosetting type forming material. When an electron beam or the like is used for the active energy ray, the active energy ray-curable forming material does not need to contain a photopolymerization initiator, but when ultraviolet rays or visible light are used for the active energy ray, it is necessary. It preferably contains a photopolymerization initiator. On the other hand, when the curable component is used as a thermosetting component, the forming material preferably contains a thermopolymerization initiator.

≪Photopolymerization initiator≫
When a radically polymerizable compound is used, the photopolymerization initiator is appropriately selected by the active energy ray. When curing by ultraviolet rays or visible light, a photopolymerization initiator that cleaves ultraviolet rays or visible light is used. Examples of the photopolymerization initiator include benzophenone compounds such as benzyl, benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2). Aromatic ketone compounds such as -propyl) ketone, α-hydroxy-α, α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, α-hydroxycyclohexylphenylketone; methoxyacetophenone, 2,2-dimethoxy- Acetphenone compounds such as 2-phenylacetophenylone, 2,2-diethoxyacetophenone, 2-methyl-1- [4- (methylthio) -phenyl] -2-morpholinopropane-1; benzoine methyl ether, Benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, anisoin methyl ether; aromatic ketal compounds such as benzyl dimethyl ketal; aromatic sulfonyl chlorides such as 2-naphthalene sulfonyl chloride. System compounds; Photoactive oxime compounds such as 1-phenone-1,1-propanedione-2- (o-ethoxycarbonyl) oxime; thioxanson, 2-chlorothioxanson, 2-methylthioxanson, 2,4- Thioxanson compounds such as dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone; camphorquinone; halogenated Examples thereof include ketones; acylphosphinoxides; and acylphosphonates.

The blending amount of the photopolymerization initiator is 20 parts by weight or less with respect to 100 parts by weight of the total amount of the curable component (radical polymerizable compound). The blending amount of the photopolymerization initiator is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight, and further preferably 0.1 to 5 parts by weight.

When the curable type forming material is used in a visible light curable type containing a radically polymerizable compound as a curable component, it is particularly preferable to use a photopolymerization initiator having high sensitivity to light of 380 nm or more. A photopolymerization initiator having high sensitivity to light of 380 nm or more will be described later.

（式中、Ｒ^１およびＲ^２は−Ｈ、−ＣＨ_２ＣＨ_３、−ｉＰｒまたはＣｌを示し、Ｒ^１およびＲ^２は同一または異なっても良い）を単独で使用するか、あるいは一般式（１）で表される化合物と後述する３８０ｎｍ以上の光に対して高感度な光重合開始剤とを併用することが好ましい。一般式（１）で表される化合物を使用した場合、３８０ｎｍ以上の光に対して高感度な光重合開始剤を単独で使用した場合に比べて密着性に優れる。一般式（１）で表される化合物の中でも、Ｒ^１およびＲ^２が−ＣＨ_２ＣＨ_３であるジエチルチオキサントンが特に好ましい。当該形成材中の一般式（１）で表される化合物の組成比率は、硬化性成分の全量１００重量部に対して、０．１〜５重量部であることが好ましく、０．５〜４重量部であることがより好ましく、０．９〜３重量部であることがさらに好ましい。 The photopolymerization initiator is a compound represented by the following general formula (1);

(In the formula, R ¹ and R ² indicate -H, -CH ₂ CH ₃ , -iPr or Cl, and R ¹ and R ² may be the same or different), or the general formula (in the formula) may be used alone. It is preferable to use the compound represented by 1) in combination with a photopolymerization initiator having high sensitivity to light of 380 nm or more, which will be described later. When the compound represented by the general formula (1) is used, the adhesion is excellent as compared with the case where a photopolymerization initiator having high sensitivity to light of 380 nm or more is used alone. Among the compounds represented by the general formula (1), diethylthioxanthone in which R ¹ and R ² are −CH ₂ CH ₃ is particularly preferable. The composition ratio of the compound represented by the general formula (1) in the forming material is preferably 0.1 to 5 parts by weight, preferably 0.5 to 4 parts by weight, based on 100 parts by weight of the total amount of the curable component. It is more preferably parts by weight, and even more preferably 0.9 to 3 parts by weight.

In addition, it is preferable to add a polymerization initiation aid as needed. Examples of the polymerization initiator include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and isoamyl 4-dimethylaminobenzoate. , And ethyl 4-dimethylaminobenzoate is particularly preferable. When a polymerization initiation aid is used, the amount added is usually 0 to 5 parts by weight, preferably 0 to 4 parts by weight, and most preferably 0 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable component. is there.

In addition, a known photopolymerization initiator can be used in combination if necessary. As the photopolymerization initiator, it is preferable to use a photopolymerization initiator having high sensitivity to light of 380 nm or more. Specifically, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 , 2- (Dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine Oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (η5-2,4-cyclopentadiene-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole-) 1-yl) -phenyl) titanium and the like can be mentioned.

（式中、Ｒ^３、Ｒ^４およびＲ^５は−Ｈ、−ＣＨ_３、−ＣＨ_２ＣＨ_３、−ｉＰｒまたはＣｌを示し、Ｒ^３、Ｒ^４およびＲ^５は同一または異なっても良い）を使用することが好ましい。一般式（２）で表される化合物としては、市販品でもある２−メチル−１−（４−メチルチオフェニル）−２−モルフォリノプロパン−１−オン（商品名：ＩＲＧＡＣＵＲＥ９０７ メーカー：ＢＡＳＦ）が好適に使用可能である。その他、２−ベンジル−２−ジメチルアミノ−１−（４−モルフォリノフェニル）−ブタノン−１（商品名：ＩＲＧＡＣＵＲＥ３６９ メーカー：ＢＡＳＦ）、２−（ジメチルアミノ）−２−［（４−メチルフェニル）メチル］−１−［４−（４−モルホリニル）フェニル］−１−ブタノン（商品名：ＩＲＧＡＣＵＲＥ３７９ メーカー：ＢＡＳＦ）が感度が高いため好ましい。 In particular, as the photopolymerization initiator, in addition to the photopolymerization initiator of the general formula (1), a compound represented by the following general formula (2);

(In the formula, R ³ , R ⁴ and R ⁵ indicate -H, -CH ₃ , -CH ₂ CH ₃ , -iPr or Cl, and R ³ , R ⁴ and R ⁵ may be the same or different). It is preferable to use it. As the compound represented by the general formula (2), 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one (trade name: IRGACURE907 manufacturer: BASF), which is also a commercially available product, is preferable. Can be used for. In addition, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (trade name: IRGACURE369 manufacturer: BASF), 2- (dimethylamino) -2-[(4-methylphenyl) Methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone (trade name: IRGACURE379 manufacturer: BASF) is preferable because of its high sensitivity.

<Radical polymerizable compound having an active methylene group and a radical polymerization initiator having a hydrogen abstraction action>
When a radical polymerizable compound having an active methylene group is used as the radical polymerizable compound in the above active energy ray-curable forming material, it is preferably used in combination with a radical polymerization initiator having a hydrogen abstraction action.

Examples of the radical polymerization initiator having a hydrogen abstraction action include a thioxanthone-based radical polymerization initiator and a benzophenone-based radical polymerization initiator. The radical polymerization initiator is preferably a thioxanthone-based radical polymerization initiator. Examples of the thioxanthone-based radical polymerization initiator include compounds represented by the above general formula (1). Specific examples of the compound represented by the general formula (1) include thioxanthone, dimethylthioxanthone, diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone and the like. Among the compounds represented by the general formula (1), diethylthioxanthone in which R ¹ and R ² are −CH ₂ CH ₃ is particularly preferable.

When the above active energy ray-curable forming material contains a radical polymerizable compound having an active methylene group and a radical polymerization initiator having a hydrogen abstraction action, when the total amount of the curable component is 100% by weight, It is preferable to contain 1 to 50% by weight of the radically polymerizable compound having an active methylene group and 0.1 to 10 parts by weight of the radical polymerization initiator with respect to 100 parts by weight of the total amount of the curable component.

≪Thermal polymerization initiator≫
As the thermal polymerization initiator, it is preferable that the polymerization is not initiated by thermal cleavage when the reinforcing film is formed. For example, the thermal polymerization initiator preferably has a 10-hour half-life temperature of 65 ° C. or higher, more preferably 75 to 90 ° C. The half-life is an index showing the decomposition rate of the polymerization initiator, and means the time until the residual amount of the polymerization initiator is halved. The decomposition temperature for obtaining a half-life at an arbitrary temperature and the half-life time at an arbitrary temperature are described in the manufacturer's catalog, etc. For example, "Organic peroxide catalog 9th edition" of Nippon Oil & Fats Co., Ltd. (May 2003) ”and so on.

Examples of the thermal polymerization initiator include lauroyl peroxide (10-hour half-life temperature: 64 ° C.), benzoyl peroxide (10-hour half-life temperature: 73 ° C.), and 1,1-bis (t-butylperoxy) -3. , 3,5-trimethylcyclohexane (10-hour half-life temperature: 90 ° C.), di (2-ethylhexyl) peroxydicarbonate (10-hour half-life temperature: 49 ° C.), di (4-t-butylcyclohexyl) Peroxydicarbonate, di-sec-butylperoxydicarbonate (10-hour half-life temperature: 51 ° C.), t-butylperoxyneodecanoate (10-hour half-life temperature: 48 ° C.), t-hexylperoxy Pivalate, t-butylperoxypivalate, dilauroyl peroxide (10-hour half-life temperature: 64 ° C.), di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2 -Ethylhexanoate (10-hour half-life temperature: 66 ° C.), di (4-methylbenzoyl) peroxide, dibenzoyl peroxide (10-hour half-life temperature: 73 ° C.), t-butylperoxyisobutyrate (10) Time half-life temperature: 81 ° C.), organic peroxides such as 1,1-di (t-hexylperoxy) cyclohexane.

Examples of the thermal polymerization initiator include 2,2'-azobisisobutyronitrile (10-hour half-life temperature: 67 ° C.) and 2,2'-azobis (2-methylbutyronitrile) (10-hour). Examples thereof include azo compounds such as half-life temperature: 67 ° C.) and 1,1-azobis-cyclohexane-1-carbonitrile (10-hour half-life temperature: 87 ° C.).

The blending amount of the thermal polymerization initiator is 0.01 to 20 parts by weight with respect to 100 parts by weight of the total amount of the curable component (radical polymerizable compound). The blending amount of the thermal polymerization initiator is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 3 parts by weight.

≪Cynic polymerization sclerotherapy type forming material≫
Examples of the curable component of the cationic polymerization curable forming material include compounds having an epoxy group and an oxetanyl group. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various generally known curable epoxy compounds can be used. Preferred epoxy compounds include compounds having at least two epoxy groups and at least one aromatic ring in the molecule (aromatic epoxy compounds) and at least one of them having at least two epoxy groups in the molecule. Examples thereof include a compound (alicyclic epoxy compound) formed between two adjacent carbon atoms constituting an alicyclic ring.

≪Photocationic polymerization initiator≫
The cationic polymerization curable forming material contains the epoxy compound and the oxetane compound described above as curable components, and since these are both cured by cationic polymerization, a photocationic polymerization initiator is blended. This photocationic polymerization initiator generates a cationic species or Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates a polymerization reaction of an epoxy group or an oxetanyl group.

<Other ingredients>
The curable forming material according to the present invention preferably contains the following components.

<Acrylic oligomer>
The active energy ray-curable forming material according to the present invention can contain an acrylic oligomer obtained by polymerizing a (meth) acrylic monomer in addition to the curable component according to the radically polymerizable compound. By containing an acrylic oligomer in the active energy ray-curable forming material, the curing shrinkage when the reinforcing film is irradiated with the active energy ray and cured is reduced, and the interfacial stress between the reinforcing film and the polarizer is reduced. can do. In order to sufficiently suppress curing shrinkage, the content of the acrylic oligomer is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, based on 100 parts by weight of the total amount of the curable component. preferable. If the content of the acrylic oligomer in the forming material is too large, the reaction rate when the forming material is irradiated with active energy rays is drastically reduced, which may result in poor curing. On the other hand, it is preferable to contain 3 parts by weight or more of the acrylic oligomer, and more preferably 5 parts by weight or more, based on 100 parts by weight of the total amount of the curable component.

Since the active energy ray-curable forming material preferably has a low viscosity in consideration of workability and uniformity during coating, an acrylic oligomer obtained by polymerizing a (meth) acrylic monomer also has a low viscosity. Is preferable. The acrylic oligomer having a low viscosity and capable of preventing the curing shrinkage of the reinforcing film preferably has a weight average molecular weight (Mw) of 15,000 or less, more preferably 10,000 or less, and particularly preferably 5,000 or less. .. On the other hand, in order to sufficiently suppress the curing shrinkage of the reinforcing film, the weight average molecular weight (Mw) of the acrylic oligomer is preferably 500 or more, more preferably 1000 or more, and preferably 1500 or more. Especially preferable. Specific examples of the (meth) acrylic monomer constituting the acrylic oligomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and 2-methyl-. 2-Nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, S-butyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, t-pentyl (Meta) acrylate, 3-pentyl (meth) acrylate, 2,2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl ( (Meta) acrylic acid (1-20 carbon atoms) alkyl esters such as meta) acrylates, 4-methyl-2-propylpentyl (meth) acrylates, N-octadecyl (meth) acrylates, and more, for example, cycloalkyl (meth). ) Acrylate (eg, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.), aralkyl (meth) acrylate (eg, benzyl (meth) acrylate, etc.), polycyclic (meth) acrylate (eg, 2-isobornyl (meth) acrylate, etc.) ) Acrylate, 2-norbornylmethyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornylmethyl (meth) acrylate, etc.), hydroxyl group-containing (meth) ) Acrylate esters (eg, hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2,3-dihydroxypropylmethyl-butyl (meth) acrylate, etc.), alkoxy group- or phenoxy group-containing (meth) acrylic Acid esters (2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxy Ethyl (meth) acrylate, etc.), epoxy group-containing (meth) acrylic acid esters (eg, glycidyl (meth) acrylate, etc.), halogen-containing (meth) acrylic acid esters (eg, 2,2,2-trifluoroethyl) (Meta) acrylate, 2,2,2-to Refluoroethyl ethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, etc.), alkylaminoalkyl (meth) Acrylate (eg, dimethylaminoethyl (meth) acrylate, etc.) and the like can be mentioned. These (meth) acrylates can be used alone or in combination of two or more. Specific examples of the acrylic oligomer include "ARUFON" manufactured by Toagosei Co., Ltd., "Actflow" manufactured by Soken Chemical Co., Ltd., and "JONCRYL" manufactured by BASF Japan Ltd.

<Photoacid generator>
The active energy ray-curable forming material can contain a photoacid generator. When the active energy ray-curable forming material contains a photoacid generator, the water resistance and durability of the reinforcing film can be dramatically improved as compared with the case where the photoacid generator is not contained. The photoacid generator can be represented by the following general formula (3).

（ただし、Ｌ^＋は、任意のオニウムカチオンを表す。また、Ｘ⁻は、ＰＦ_６ ⁻、ＳｂＦ_６ ⁻、ＡｓＦ_６ ⁻、ＳｂＣｌ_６ ⁻、ＢｉＣｌ_５ ⁻、ＳｎＣｌ_６ ⁻、ＣｌＯ_４ ⁻、ジチオカルバメートアニオン、ＳＣＮ−よりからなる群より選択されるカウンターアニオンを表す。） General formula (3)

(However, L ⁺ represents an arbitrary onium cation. X ⁻ is PF ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ ⁻ , SbCl ₆ ⁻ , BiCl ₅ ⁻ , SnCl ₆ ⁻ , ClO ₄ ⁻ , dithiocarbamate. Represents a counter anion selected from the group consisting of anions and SCN-).

Specific examples of preferred onium salts constituting the photoacid ^{_{generator, PF 6 -, SbF 6 -}} , AsF 6 -, SbCl 6 -, BiCl 5 -, SnCl 6 -, ClO 4 -, dithiocarbamate anion, SCN ^- It is an onium salt composed of more selected anions.

Specifically, "Cyracure UVI-6992", "Cyracure UVI-6974" (above, manufactured by Dow Chemical Japan Co., Ltd.), "Adeka Putmer SP150", "Adeka Putmer SP152", "Adeka Putmer" SP170 "," ADEKA PUTMER SP172 "(above, ADEKA Corporation)," IRGACURE250 "(manufactured by Ciba Specialty Chemicals)," CI-5102 "," CI-2855 "(above, manufactured by Nippon Soda), "Sun Aid SI-60L", "Sun Aid SI-80L", "Sun Aid SI-100L", "Sun Aid SI-110L", "Sun Aid SI-180L" (all manufactured by Sanshin Chemical Co., Ltd.), "CPI-100P", "CPI-100A" (manufactured by Sun Appro Co., Ltd.), "WPI-069", "WPI-113", "WPI-116", "WPI-041", "WPI-044", "WPI-054", "WPI-055", "WPAG-281", "WPAG-567", and "WPAG-596" (all manufactured by Wako Pure Chemical Industries, Ltd.) are mentioned as preferable specific examples of the photoacid generator.

The content of the photoacid generator is 10 parts by weight or less, preferably 0.01 to 10 parts by weight, and 0.05 to 5 parts by weight with respect to 100 parts by weight of the total amount of the curable component. It is more preferable, and it is particularly preferable that it is 0.1 to 3 parts by weight.

The reinforcing film is formed by the curing type forming material by applying a curing type forming material on the surface of the polarizer and then curing.

The polarizer may be subjected to a surface modification treatment before applying the curable forming material. Specific treatments include corona treatment, plasma treatment, and saponification treatment.

The coating method of the curable forming material is appropriately selected depending on the viscosity of the curable forming material and the target thickness. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse and offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater and the like. In addition, a method such as a dipping method can be appropriately used for coating.

<Hardening of forming material>
The curable type forming material is used as an active energy ray curable type forming material or a thermosetting type forming material. The active energy ray-curable forming material can be used in the form of electron beam-curable type, ultraviolet-curable type, and visible light-curable type.

≪Active energy ray sclerotherapy type≫
In the active energy ray-curable forming material, after coating the polarizer with the active energy ray-curable forming material, the active energy ray-curable forming material is irradiated with active energy rays (electron beam, ultraviolet rays, visible light, etc.) to obtain the active energy ray-curable forming material. It hardens to form a reinforcing film. The irradiation direction of the active energy ray (electron beam, ultraviolet ray, visible light, etc.) can be any suitable direction. Preferably, the irradiation is performed from the reinforcing film side.

≪Electron beam curing type≫
In the electron beam curing type, any appropriate conditions can be adopted as the electron beam irradiation conditions as long as the active energy ray curing type forming material can be cured. For example, in electron beam irradiation, the acceleration voltage is preferably 5 kV to 300 kV, and more preferably 10 kV to 250 kV. If the accelerating voltage is less than 5 kV, the electron beam may not reach the deepest part of the reinforcing film and curing may be insufficient. If the accelerating voltage exceeds 300 kV, the penetrating force through the sample is too strong and damages the polarizer. There is a risk. The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy. When the irradiation dose is less than 5 kGy, the adhesive is insufficiently cured, and when it exceeds 100 kGy, the polarizer is damaged, the mechanical strength is lowered and yellowing occurs, and the predetermined optical characteristics cannot be obtained.

The electron beam irradiation is usually performed in an inert gas, but if necessary, it may be performed in the atmosphere or under the condition that a small amount of oxygen is introduced.

≪UV curable type, visible light curable type≫
As the active energy ray, it is preferable to use one containing visible light having a wavelength range of 380 nm to 450 nm, particularly an active energy ray having the largest irradiation amount of visible light having a wavelength range of 380 nm to 450 nm. As the active energy ray, a gallium-filled metal halide lamp and an LED light source that emits a wavelength range of 380 to 440 nm are preferable. Alternatively, with ultraviolet rays such as low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high pressure mercury lamp, incandescent lamp, xenon lamp, halogen lamp, carbon arc lamp, metal halide lamp, fluorescent lamp, tungsten lamp, gallium lamp, excima laser or sunlight. A light source containing visible light can be used, and a bandpass filter can be used to block ultraviolet rays having a wavelength shorter than 380 nm.

≪Thermosetting type≫
On the other hand, in the thermosetting type forming material, after applying it to a polarizer, it is heated to initiate polymerization with a thermal polymerization initiator to form a cured product layer (reinforcing film). The heating temperature is set according to the thermal polymerization initiator, but is about 60 to 200 ° C., preferably 80 to 150 ° C.

Further, as the material for forming the reinforcing film, for example, a cyanoacrylate-based forming material, an epoxy-based forming material, or an isocyanate-based forming material can be used.

Examples of the cyanoacrylate-based forming material include alkyl-α-cyanoacrylate such as methyl-α-cyanoacrylate, ethyl-α-cyanoacrylate, butyl-α-cyanoacrylate, and octyl-α-cyanoacrylate, and cyclohexyl-α-. Examples thereof include cyanoacrylate and methoxy-α-cyanoacrylate. As the cyanoacrylate-based forming material, for example, a material used as a cyanoacrylate-based adhesive can be used.

The epoxy-based forming material may be used as an epoxy resin alone, or may contain an epoxy curing agent. When the epoxy resin is used alone, it is cured by adding a photopolymerization initiator and irradiating it with active energy rays. When an epoxy curing agent is added as the epoxy-based forming material, for example, one used as an epoxy-based adhesive can be used. The epoxy-based forming material can be used as a one-component type containing an epoxy resin and a curing agent thereof, but is also used as a two-component type in which a curing agent is mixed with an epoxy resin. Epoxy-based forming materials are usually used as a solution. The solution may be a solvent system or an aqueous solution such as an emulsion, a colloidal dispersion, or an aqueous solution.

Examples of the epoxy resin include various compounds containing two or more epoxy groups in the molecule. For example, bisphenol type epoxy resin, aliphatic epoxy resin, aromatic epoxy resin, halogenated bisphenol type epoxy resin, biphenyl Examples include based epoxy resins. The epoxy resin can be appropriately determined according to the epoxy equivalent and the number of functional groups, but from the viewpoint of durability, an epoxy resin having an epoxy equivalent of 500 or less is preferably used.

The curing agent for the epoxy resin is not particularly limited, and various types such as phenol resin type, acid anhydride type, carboxylic acid type, and polyamine type can be used. As the phenolic resin-based curing agent, for example, phenol novolac resin, bisphenol novolac resin, xylylene phenol resin, cresol novolac resin and the like are used. Examples of the acid anhydride-based curing agent include maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and succinic anhydride, and examples of the carboxylic acid-based curing agent include carboxylic acids such as pyromellitic acid and trimellitic acid. Examples thereof include block carboxylic acids to which acids and vinyl ether are added. Further, as the epoxy-based two-component forming material, for example, a material composed of two liquids of epoxy resin and polythiol, a material composed of two liquids of epoxy resin and polyamide, and the like can be used.

The amount of the curing agent to be blended varies depending on the equivalent amount with the epoxy resin, but is preferably 30 to 70 parts by weight, more preferably 40 to 60 parts by weight, based on 100 parts by weight of the epoxy resin.

Further, as the epoxy-based forming material, various curing accelerators can be used in addition to the epoxy resin and its curing agent. Examples of the curing accelerator include various imidazole compounds and derivatives thereof, dicyandiamide and the like.

Examples of the isocyanate-based forming material include those used as a cross-linking agent in the formation of the pressure-sensitive adhesive layer. As the isocyanate-based cross-linking agent, a compound having at least two isocyanate groups can be used. For example, the polyisocyanate compound can be used as an isocyanate-based forming material. Specifically, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, 1,3-bisisocyanatomethylcyclohexane, hexamethylene diisocyanate, tetramethylxylylene diisocyanate, m-isopropenyl-α, α-Dimethylbenzyl isocyanate, methylenebis4-phenylisocyanate, p-phenylenediisocyanate or dimer of these, trimeric such as trisisocyanurate (6-incyanate hexyl), and these biurets and trimethylolpropane. Examples thereof include those reacted with polyhydric alcohol and polyhydric amine. Further, as the isocyanate-based cross-linking agent, those having three or more isocyanate groups such as trisisocyanurate (6-incyanate hexyl) are preferable. Examples of the isocyanate-based forming material include those used as an isocyanate-based adhesive.

Among the isocyanate-based forming materials, in the present invention, it is preferable to use a material having a rigid structure in which a cyclic structure (benzene ring, cyanurate ring, isocyanurate ring, etc.) occupies a large proportion in the structure. As the isocyanate-based forming material, for example, trimethylolpropane-tri-tolylene isocyanate, tris (hexamethylene diisocyanate) isocyanurate and the like are preferably used.

As the isocyanate-based cross-linking agent, one in which a protecting group is added to a terminal isocyanate group can also be used. Protecting groups include oxime and lactam. When the isocyanate group is protected, the protecting group is dissociated from the isocyanate group by heating, and the isocyanate group reacts.

Further, a reaction catalyst can be used to increase the reactivity of the isocyanate group. The reaction catalyst is not particularly limited, but a tin catalyst or an amine catalyst is preferable. One kind or two or more kinds of reaction catalysts can be used. The amount of the reaction catalyst used is usually 5 parts by weight or less with respect to 100 parts by weight of the isocyanate-based cross-linking agent. When the amount of the reaction catalyst is large, the crosslinking reaction rate becomes high and the forming material foams. Sufficient adhesiveness cannot be obtained even if the foamed forming material is used. Generally, when a reaction catalyst is used, 0.01 to 5 parts by weight, more preferably 0.05 to 4 parts by weight.

As the tin catalyst, either an inorganic catalyst or an organic catalyst can be used, but an organic catalyst is preferable. Examples of the inorganic tin-based catalyst include stannous chloride and stannic chloride. The organic tin catalyst preferably has at least one organic group such as an aliphatic group having a skeleton such as a methyl group, an ethyl group, an ether group or an ester group, and an alicyclic group. For example, tetra-n-butyltin, tri-n-butyltin acetate, n-butyltin trichloride, trimethyltin hydroxide, dimethyltin dichloride, dibutyltin dilaurate, etc. can be mentioned.

The amine-based catalyst is not particularly limited. For example, those having at least one organic group such as an alicyclic group such as quinoclydin, amidine, and diazabicycloundecene are preferable. Other examples of the amine-based catalyst include triethylamine and the like. Examples of reaction catalysts other than the above include cobalt naphthenate, benzyltrimethylammonium hydroxide and the like.

The isocyanate-based forming material is usually used as a solution. The solution may be a solvent system or an aqueous solution such as an emulsion, a colloidal dispersion, or an aqueous solution. The organic solvent is not particularly limited as long as the components constituting the forming material are uniformly dissolved. Examples of the organic solvent include toluene, methyl ethyl ketone, ethyl acetate and the like. In the case of an aqueous system, for example, alcohols such as n-butyl alcohol and isopropyl alcohol, and ketones such as acetone can be blended. When making it aqueous, a dispersant is used, or a functional group with low reactivity with isocyanate groups such as carboxylates, sulfonates, and quaternary ammonium salts, and aqueous dispersion of polyethylene glycol and the like are used in isocyanate-based cross-linking agents. This can be done by introducing a sex component.

The formation (curing) of the reinforcing film by the cyanoacrylate-based forming material, the epoxy-based forming material, or the isocyanate-based forming material can be appropriately selected depending on the type of the forming material, but is usually 30 to 100 ° C. It is carried out by drying at about 50 to 80 ° C. for about 0.5 to 15 minutes. In the case of a cyanoacrylate-based forming material, since it cures quickly, the reinforcing film can be formed in a time shorter than the above time.

Further, polyurethane can be used as the material for forming the reinforcing film. As the polyurethane, it is preferable to use a high molecular weight polyol compound and / or a reaction product of a low molecular weight polyol and an isocyanate compound, and a reaction product of an isocyanate compound. In addition to the high molecular weight polyol compound and the isocyanate compound, the polyurethane can be further reacted with a low molecular weight polyamino compound and / or a polyol compound as a chain extender.

The polymer polyol compound preferably has a weight average molecular weight of 100 to 4000 and has two or more hydroxyl groups in one molecule, and a polyether polyol, a polyester polyol, a polycarbonate polyol, or the like is used. The polymer polyol compound preferably has a weight average molecular weight of 500 to 4000, more preferably 600 to 3500, and even more preferably 1000 to 3000.

Examples of the polyether polyol include an aliphatic polyether polyol and an aromatic polyether polyol. More specifically, for example, ethylene oxide is added to low molecular weight polyols such as dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol and hexamethylene glycol, and trihydric alcohols such as trimethylolpropane, glycerin and pentaerythritol. , Propylene oxide, tetrahydrofuran and the like are added and polymerized to form a polyether. These may be used alone or in combination of two or more.

Examples of the polyester polyol include an aliphatic polyester polyol and an aromatic polyester polyol. More specifically, the above alcohols such as dihydric alcohol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol and neopentyl glycol, and two bases such as adipic acid, azelaic acid and sebatic acid Polyester composed of a polycondensate with an acid is used. These may be used alone or in combination of two or more.

In addition, polydiene-based polyols such as polybutadiene, butadiene-acrylonitrile copolymer, and polyisobutylene having hydroxyl groups at both ends of the molecule, polybutadiene hydrogenated products, polyisobutylene hydrogenated products, and poly having hydroxyl groups at both ends of the molecule. Polyolefin-based polyols such as isobutylene can also be mentioned.

In addition, examples of the polyamino compound used as the chain extender include an aliphatic polyamino compound and an aromatic polyamino compound. More specifically, for example, ethylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), diethyltoluenediamine (DETDA), 44'-bis- (sec-butyl) diphenylmethane, 2,4. Examples thereof include -tolylenediamine, 2,6-tolylenediamine, xylylenediamine, hexanediamine and isophoronediamine. Of these, ethylenediamine and the like are preferable. These may be used alone or in combination of two or more.

Further, examples of the polyol compound used as the low molecular weight polyol and the chain extender include low molecular weight polyols exemplified as polyether polyols and polyester polyols.

The chain extender is preferably used in an amount of 0.1 to 10 parts by weight, more preferably 0.5 to 7 parts by weight, and 1 to 5 parts by weight, based on 100 parts by weight of the polymer polyol compound. It is more preferable to be. By using the chain extender, the molecular weight can be sufficiently increased and the durability can be improved.

The isocyanate compound is a polyisocyanate (isocyanate compound) having two or more isocyanate groups, and the same one as the isocyanate-based forming material can be used. Further, the isocyanate compound can also be used as a urethane prepolymer obtained by reacting the low molecular weight polyol exemplified in the polyester polyol with the isocyanate compound exemplified above in advance.

Further, in order to react the isocyanate group of these polyisocyanates with the hydroxyl group, it is desirable to use dibutyltin dilaurate, tin octoate, 1,4-diazabicyclo (2,2,2) octane or the like as a catalyst.

The formation (curing) of the reinforcing film by polyurethane may be usually carried out by applying a liquid material (coating liquid) of polyurethane prepared in advance to a polarizer, or contains the above-mentioned polymer polyol compound and isocyanate compound. After applying the composition to the polarizer, a reinforcing film may be formed of polyurethane as a cured reaction product. The reinforcing film can be formed by drying at about 30 to 100 ° C., preferably 50 to 80 ° C. for about 0.5 to 15 minutes.

Further, after the formation of the reinforcing film (curing: this is referred to as initial curing), an annealing treatment may be performed. The annealing treatment accelerates the reaction, especially in an isocyanate-based forming agent, a polyurethane-based forming material, etc., when the isocyanate has not sufficiently reacted even after the initial curing (a state in which reactive groups remain in the reinforcing film). Can be implemented for the purpose. The annealing treatment can be performed in any atmosphere under dry or humid conditions. The annealing treatment temperature is about 30 to 100 ° C., preferably 50 to 80 ° C., similar to the conditions at the time of initial curing. There is no particular limitation on the annealing treatment time.

The weight average molecular weight of polyurethane is preferably 30,000 to 200,000, more preferably 40 to 150,000, and even more preferably 50,000 to 130,000.

(Measurement of weight average molecular weight)
The weight average molecular weights of the high molecular weight polyol compound and polyurethane were measured under the following conditions by GPC (gel permeation chromatography).
Analyzer: HLC-8120GPC manufactured by Tosoh.
Column: Made by Tosoh, G7000HXL + GMHXL + GMHXL.
Column size: 7.8 mm φ x 30 cm each, 90 cm in total.
Column temperature: 40 ° C.
Flow velocity: 0.8 ml / min.
Injection volume: 100 μl.
Eluent: tetrahydrofuran.
Detector: Suggested refractometer.
Standard sample: polystyrene.

Further, as a material for forming the reinforcing film, it has a functional group capable of forming a covalent bond with PVA such as an isocyanate group and an epoxy group, and also has a carbon-carbon double bond such as a (meth) acryloyl group and a vinyl group. A compound having a radically polymerizable functional group of can be used. Examples of the compound include 2-isocyanatoethylacrylate (manufactured by Showa Denko, product name Karenz AOI), 1,1- (bisacryloyloxymethyl) ethyl isocyanate (manufactured by Showa Denko, Karenz BEI) and the like. Be done. Further, as the compound, a reaction product of a polymer containing a diisocyanate compound as a constituent component and a hydroxyl group-containing (meth) acrylate can be used. Examples of such a reaction product include a reaction product of 2-hydroxyethyl acrylate and a polymer containing 1,6-diisocyanatohexane as a constituent component (manufactured by BASF, product name: Laromar LR9000).

Since the compound has a functional group such as an isocyanate group and an epoxy group, a reinforcing film can be formed by thermosetting in the same manner as the isocyanate-based forming agent, and further, an annealing treatment can be performed. Further, since the compound has a radically polymerizable functional group, it can be used as an active energy ray-curable type or thermosetting type forming material related to a radical polymerization curing type forming material. When used as a radical polymerization curable forming material, the compound may be used in combination with other radical polymerizable compounds.

Further, the reinforcing film may be formed of a forming material that does not contain a curable component, or may be formed of, for example, a forming material that contains the polyvinyl alcohol-based resin as a main component. The polyvinyl alcohol-based resin forming the reinforcing film may be the same as or different from the polyvinyl alcohol-based resin contained in the polarizer as long as it is a “polyvinyl alcohol-based resin”.

Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol. Polyvinyl alcohol is obtained by saponification of polyvinyl acetate. Examples of the polyvinyl alcohol-based resin include a saponified product of a copolymer of vinyl acetate and a monomer having copolymerizability. When the copolymerizable monomer is ethylene, an ethylene-vinyl alcohol copolymer can be obtained. Examples of the copolymerizable monomer include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, and (meth) acrylic acid and esters thereof; ethylene, propylene and the like. α-olefin, (meth) allylsulfonic acid (soda), sodium sulfonic acid (monoalkylmalate), sodium disulfonic acid alkylmalate, N-methylolacrylamide, acrylamidealkylsulfonic acid alkali salt, N-vinylpyrrolidone, N- Examples include vinylpyrrolidone derivatives. These polyvinyl alcohol-based resins may be used alone or in combination of two or more. From the viewpoint of controlling the amount of heat of crystal melting of the reinforcing film to 30 mj / mg or more to satisfy the heat resistance to moisture and water, polyvinyl alcohol obtained by saponifying polyvinyl acetate is preferable.

For example, a polyvinyl alcohol-based resin having a saponification degree of 95% or more can be used, but the amount of heat of crystal melting of the reinforcing film is controlled to 30 mj / mg or more to satisfy moist heat resistance and water resistance. From the viewpoint, the degree of saponification is preferably 99.0% or more, more preferably 99.7% or more. The degree of saponification represents the ratio of units that are actually saponified to vinyl alcohol units among the units that can be converted to vinyl alcohol units by saponification, and the residue is a vinyl ester unit. The degree of saponification can be determined according to JIS K 6726-1994.

As the average degree of polymerization of the polyvinyl alcohol-based resin, for example, one having a degree of polymerization of 500 or more can be used, but from the viewpoint of controlling the amount of heat of crystal melting of the reinforcing film to 30 mj / mg or more to satisfy moist heat resistance and water resistance. From the above, the average degree of polymerization is preferably 1000 or more, more preferably 1500 or more, and further preferably 2000 or more. The average degree of polymerization of the polyvinyl alcohol-based resin is measured according to JIS-K6726.

Further, as the polyvinyl alcohol-based resin, a modified polyvinyl alcohol-based resin having a hydrophilic functional group in the side chain of the polyvinyl alcohol or a copolymer thereof can be used. Examples of the hydrophilic functional group include an acetoacetyl group and a carbonyl group. In addition, modified polyvinyl alcohol obtained by acetalizing, urethanizing, etherifying, grafting, or phosphoric acid esterifying a polyvinyl alcohol-based resin can be used.

The forming material containing the polyvinyl alcohol-based resin as a main component may contain a curable component (crosslinking agent) or the like. The ratio of the polyvinyl alcohol-based resin in the reinforcing film or the forming material (solid content) is preferably 80% by weight or more, more preferably 90% by weight or more, and further preferably 95% by weight or more. However, it is preferable that the forming material does not contain a curable component (crosslinking agent) from the viewpoint that the amount of heat of crystal melting of the reinforcing film can be easily controlled to 30 mj / mg or more.

As the cross-linking agent, a compound having at least two functional groups reactive with the polyvinyl alcohol-based resin can be used. For example, alkylenediamines having two alkylene groups and two amino groups such as ethylenediamine, triethylenediamine and hexamethylenediamine; tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropan tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylenebis (Isocyanates such as 4-phenylmethane triisocyanate, isophorone diisocyanate and their ketooxime block products or phenol block products; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerinji or triglycidyl ether, 1,6-hexane Epoxys such as diol diglycidyl ether, trimethylpropan triglycidyl ether, diglycidyl aniline, diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butylaldehyde; Dialdehydes such as dialdehyde, malein dialdehyde, and phthaldialdehyde; amino-formaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetguanamine, and condensates of benzoguanamine and formaldehyde; Adipic acid dihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinate dihydrazide, glutarate dihydrazide, isophthalic acid dihydrazide, sebacic acid dihydrazide, maleate dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide, etc. Examples thereof include water-soluble dihydrazines such as −dihydrazine, propylene-1,3-dihydrazine, butylene-1,4-dihydrazine. Among these, amino-aldehyde resin and water-soluble dihydrazine are preferable. Amino-aldehyde As the resin, a compound having a methylol group is preferable, and among them, methylol melamine, which is a compound having a methylol group, is particularly preferable.

The curable component (crosslinking agent) can be used from the viewpoint of improving water resistance, and the ratio thereof is 20 parts by weight or less, 10 parts by weight or less, and 5 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol-based resin. It is preferably as follows.

The forming material is prepared as a solution in which the polyvinyl alcohol-based resin is dissolved in a solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide N-methylpyrrolidone, various glycols, polyhydric alcohols such as alcohols, and amines such as ethylenediamine and diethylenetriamine. These can be used alone or in combination of two or more. Among these, it is preferable to use it as an aqueous solution using water as a solvent. The concentration of the polyvinyl alcohol-based resin in the forming material (for example, an aqueous solution) is not particularly limited, but is 0.1 to 15% by weight, preferably 0.5, in consideration of coatability, standing stability, and the like. It is 10% by weight.

Examples of the additive that can be blended in the forming material (for example, an aqueous solution) include a plasticizer, a surfactant, and the like. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactant include nonionic surfactants.

The reinforcing film can be formed by applying the forming material to a polarizer and drying it. The coating operation is not particularly limited, and any suitable method can be adopted. For example, various means such as a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, and a knife coating method (comma coating method, etc.) can be adopted.

<Surface treatment layer>
A surface treatment layer can be provided on one side or both sides of the flexible polarizing film of the present invention. Examples of the surface treatment layer include a hard coat layer, an antiglare treatment layer, an antireflection layer, and a sticking prevention layer. The surface treatment layer is preferably a hard coat layer. As the material for forming the hard coat layer, for example, a thermoplastic resin or a material that is cured by heat or radiation can be used. Examples of the material include radiation curable resins such as thermosetting resins, ultraviolet curable resins, and electron beam curable resins. Among these, an ultraviolet curable resin that can efficiently form a cured resin layer by a simple processing operation by a curing treatment by ultraviolet irradiation is preferable. Examples of these curable resins include various types such as polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, epoxy-based, and melamine-based resins, and include these monomers, oligomers, and polymers.

Further, as the surface treatment layer, an antiglare treatment layer or an antireflection layer for the purpose of improving visibility can be provided. Further, an antiglare treatment layer and an antireflection layer can be provided on the hard coat layer. The constituent material of the antiglare treatment layer is not particularly limited, and for example, a radiation-curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used. As the antireflection layer, titanium oxide, zirconium oxide, silicon oxide, magnesium fluoride and the like are used. A plurality of antireflection layers can be provided. In addition, examples of the surface treatment layer include a sticking prevention layer and the like.

The thickness of the surface-treated layer can be appropriately set depending on the type of the surface-treated layer, but is generally preferably 0.1 to 100 μm. For example, the thickness of the hard coat layer is preferably 0.5 to 20 μm.

<Adhesive layer>
An adhesive layer can be provided on one or both sides of the flexible polarizing film of the present invention. An appropriate adhesive can be used for forming the pressure-sensitive adhesive layer, and the type thereof is not particularly limited. As adhesives, rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone adhesives, polyacrylamide adhesives, Examples include cellulose-based adhesives.

Among these adhesives, those having excellent optical transparency, exhibiting appropriate wettability, cohesiveness and adhesiveness, and excellent weather resistance and heat resistance are preferably used. Acrylic adhesives are preferably used to exhibit such characteristics.

As a method of forming the pressure-sensitive adhesive layer, for example, a method of applying the pressure-sensitive adhesive to a separator or the like that has been peeled off, drying and removing a polymerization solvent or the like to form a pressure-sensitive adhesive layer, and then transferring the pressure-sensitive adhesive layer to a flexible polarizing film, or flexible It is produced by a method of applying the pressure-sensitive adhesive to a polarizing film and drying and removing a polymerization solvent or the like to form a pressure-sensitive adhesive layer on a polarizing element. When applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be newly added as appropriate.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm. It is preferably 2 to 50 μm, more preferably 2 to 40 μm, and even more preferably 5 to 35 μm.

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected by a sheet (separator) that has been peeled off until it is put into practical use.

<Surface protection film>
Further, a surface protective film can be provided on the flexible polarizing film of the present invention. The surface protective film usually has a base film and an adhesive layer, and protects the flexible polarizing film through the adhesive layer.

As the base film of the surface protective film, a film material having or isotropic is selected from the viewpoint of inspectability and controllability. Examples of the film material include polyester resins such as polyethylene terephthalate films, cellulose resins, acetate resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and acrylic resins. Examples include transparent polymers such as resins. Of these, polyester-based resins are preferable. The base film can be used as a laminate of one or more film materials, or a stretched product of the film can also be used. The thickness of the base film is generally 500 μm or less, preferably 10 to 200 μm.

As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the surface protective film, a pressure-sensitive adhesive based on a polymer such as (meth) acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer. Can be appropriately selected and used. From the viewpoint of transparency, weather resistance, heat resistance and the like, an acrylic pressure-sensitive adhesive using an acrylic polymer as a base polymer is preferable. The thickness of the pressure-sensitive adhesive layer (dry film thickness) is determined according to the required adhesive strength. It is usually about 1 to 100 μm, preferably 5 to 50 μm.

The surface protective film may be provided with a peeling treatment layer by a low adhesive material such as silicone treatment, long chain alkyl treatment, or fluorine treatment on the opposite surface of the base film to which the pressure-sensitive adhesive layer is provided. ..

<Other optical layers>
The flexible polarizing film of the present invention is intended to expand various applications that cannot be applied to conventional polarizers and polarizing films as an alternative to a polarizer or a polarizing film (a polarizing element provided with a transparent protective film). For example, it can be used as an optical film laminated with another optical layer. The optical layer is not particularly limited, but for example, when the flexible polarizing film of the present invention is used as a substitute for a polarizer, a protective film (phase difference film, brightness improving film, diffusion) used for protecting the polarizer is used. (Including films, etc.) can be used, and when used as a substitute for polarizing films, reflectors, transflective plates, retardation films (including wave plates such as 1/2 and 1/4), and viewing angle compensation films. For example, one or two or more optical layers that may be used for forming an image display device such as a liquid crystal display device or an organic EL display device can be used.

<Intervening layer>
The optical layer and the flexible polarizing film can be laminated via an intervening layer such as an adhesive layer, an adhesive layer, and an undercoat layer (primer layer). At this time, it is desirable that both are laminated without an air gap by an intervening layer.

The flexible polarizing film of the present invention or an optical film using the same can be preferably used for forming various image display devices such as a liquid crystal display device and an organic EL display device. The liquid crystal display device can be formed according to the conventional method. That is, the liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell, a flexible polarizing film of the present invention or an optical film using the same, and components such as a lighting system as needed, and incorporating a drive circuit. However, there is no particular limitation except that the flexible polarizing film of the present invention is used, and the conventional method can be applied. As the liquid crystal cell, any type such as IPS type and VA type can be used, but the IPS type is particularly suitable.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the examples shown below. In addition, each part and% in each example is based on weight. All the conditions for leaving at room temperature, which are not specified below, are 23 ° C. and 65% RH.

<Preparation of polarizer A0>
Amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a water absorption rate of 0.75% and a Tg of 75 ° C. One side of the base material is subjected to corona treatment, and the corona treated surface is made of polyvinyl. Alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (degree of polymerization 1200, degree of acetoacetyl modification 4.6%, degree of saponification 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. , Trade name "Gosefimer Z200") at a ratio of 9: 1 was applied and dried at 25 ° C. to form a PVA-based resin layer having a thickness of 11 μm to prepare a laminate.
The obtained laminate was uniaxially stretched at the free end in the longitudinal direction (longitudinal direction) 2.0 times between rolls having different peripheral speeds in an oven at 120 ° C. (aerial auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 30 ° C. (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, the polarizing plate was immersed in a dyeing bath having a liquid temperature of 30 ° C. while adjusting the iodine concentration and the immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 parts by weight of iodine was mixed with 100 parts by weight of water, and 1.0 part by weight of potassium iodide was mixed and immersed in the obtained iodine aqueous solution for 60 seconds (dyeing treatment). ..
Next, it was immersed in a cross-linked bath at a liquid temperature of 30 ° C. (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds. (Crossing treatment).
Then, the laminate is immersed in an aqueous solution of boric acid having a liquid temperature of 70 ° C. (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water). However, uniaxial stretching was performed between rolls having different peripheral speeds so that the total stretching ratio was 5.5 times in the longitudinal direction (longitudinal direction) (underwater stretching treatment).
Then, the laminate was immersed in a washing bath having a liquid temperature of 30 ° C. (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
From the above, an optical film laminate containing a polarizer having a thickness of 5 μm was obtained.

<Preparation of polarizers A1 to A2>
In the above-mentioned production of the polarizer A0, the polarizers A1 to A2 were produced in the same manner as in the production of the polarizer A0 except that the production conditions were changed as shown in Table 1. Table 1 shows the thickness, optical characteristics (single transmittance, degree of polarization), and boric acid concentration of the polarizers A0 to A2.

<Preparation of Polarizer B1 (polarizer with a thickness of 12 μm)>
A polyvinyl alcohol film having an average degree of polymerization of 2400 and a saponification degree of 99.9 mol% and a thickness of 30 μm was immersed in warm water at 30 ° C. for 60 seconds to swell. Then, the film was dyed by immersing it in an aqueous solution having a concentration of iodine / potassium iodide (weight ratio = 0.5 / 8) at a concentration of 0.3% and stretching it up to 3.5 times. Then, stretching was carried out in a boric acid ester aqueous solution at 65 ° C. so that the total stretching ratio was 6 times. After stretching, it was dried in an oven at 40 ° C. for 3 minutes to obtain a polarizer B1. The thickness of the obtained polarizer B1 was 12 μm. The optical characteristics of the obtained polarizer B1 were a transmittance of 42.8% and a degree of polarization of 99.99%.

<Preparation of Polarizer B2 (polarizer with a thickness of 23 μm)>
A polyvinyl alcohol film having an average degree of polymerization of 2400 and a saponification degree of 99.9 mol% and a thickness of 75 μm was immersed in warm water at 30 ° C. for 60 seconds to swell. Then, the film was dyed by immersing it in an aqueous solution having a concentration of iodine / potassium iodide (weight ratio = 0.5 / 8) at a concentration of 0.3% and stretching it up to 3.5 times. Then, stretching was carried out in a boric acid ester aqueous solution at 65 ° C. so that the total stretching ratio was 6 times. After stretching, it was dried in an oven at 40 ° C. for 3 minutes to obtain a polarizer B2. The thickness of the obtained polarizer B2 was 23 μm. The optical characteristics of the obtained polarizer B2 were a transmittance of 42.8% and a degree of polarization of 99.99%.

<Reinforcing film forming material>
(1) Polyurethane-based material 50 parts of urethane prepolymer (Tosoh, Coronate L) composed of tolylene diisocyanate and trimethylolpropane, 50 parts of polycarbonate polyol (Desmophen C3100XP, manufactured by Sumika Bayer Urethane), dioctyltin dilaurate 0.1 part of a catalyst (Envirizer OL-1 manufactured by Tokyo Fine Chemicals Co., Ltd.) was added, and methyl isobutyl ketone was used as a solvent to obtain a coating liquid adjusted to a solid content concentration of 35%.

(2) UV curable material A reaction product of 2-hydroxyethyl acrylate and a polymer containing 1,6-diisocyanatohexane in 50 parts of a urethane acrylate oligomer (manufactured by Nippon Synthetic Chemical Co., Ltd., Shikou UV1700TL) ( 50 parts of BASF, product name Laromar LR9000) and 3 parts of photoinitiator (BASF, IRGACURE907) were added to obtain a coating solution adjusted to a solid content concentration of 35% using methylisocyanate ketone as a solvent. ..

(3) Water-based Resin Emulsion Material A coating liquid adjusted to a solid content concentration of 30% was obtained by adding pure water as a solvent to an acrylic emulsion (trade name: SE-2915E manufactured by Taisei Fine Chemicals Co., Ltd.).

<Protective film (acrylic) and adhesive>
A corona-treated surface of a (meth) acrylic resin film having a lactone ring structure having a thickness of 20 μm was used.

As an adhesive to be applied to the above protective film (acrylic), 40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloylmorpholin (ACMO), and 3 parts by weight of the photoinitiator "IRGACURE 819" (manufactured by BASF). Was mixed to prepare an ultraviolet curable adhesive.

Example 1 (Preparation of Flexible Polarizing Film)
The polyurethane material (1) of the reinforcing film was cured on the polarizer (first surface) of the polarizer A0 (optical film laminate containing a polarizer having a thickness of 5 μm) obtained above by using a wire bar coater. After coating to a thickness of 5 μm, the first reinforcing film is formed by initial curing at 60 ° C. for 10 minutes and then annealing under the conditions of 60 ° C. for 12 hours. did. Next, a surface protective film (manufactured by Nitto Denko, RP301) was attached onto the first reinforcing film, and then the amorphous PET base material of the optical film laminate was peeled off. Then, the polyurethane material (1) of the reinforcing film is coated on the polarizer (the second surface which is the peeling surface) using a wire bar coater so that the thickness after curing becomes 5 μm, and then 60 ° C. The second reinforcing film was formed by initial curing under the condition of 10 minutes and then annealing treatment under the conditions of 60 ° C. for 12 hours. Then, by removing the surface protective film bonded on the first reinforcing film, a flexible polarizing film having reinforcing films on both sides of the polarizer was obtained.

Examples 2-4
A flexible polarizing film having reinforcing films on both sides of the polarizing film was produced in the same manner as in Example 1 except that the type of the polarizer and the thickness of the reinforcing film were changed as shown in Table 2 in Example 1. ..

Example 5 (Preparation of Flexible Polarizing Film)
The UV curable material (2) of the reinforcing film was applied to the polarizer (first surface) of the polarizer A0 (optical film laminate containing a polarizer having a thickness of 5 μm) obtained above by using a wire bar coater. After coating so that the thickness after curing was 5 μm, the mixture was heated at 60 ° C. for 1 minute. The coated film after heating was irradiated with ultraviolet rays having an integrated light intensity of 300 mJ / cm ^{2 with} a high-pressure mercury lamp to form a first reinforcing film. Next, a surface protective film (manufactured by Nitto Denko, RP301) was attached onto the first reinforcing film, and then the amorphous PET base material of the optical film laminate was peeled off. Then, the UV curable material (2) of the reinforcing film is applied to the polarizer (the second surface which is the peeling surface) using a wire bar coater so that the thickness after curing becomes 5 μm, and then 60. It was heated at ° C. for 1 minute. A second reinforcing film was formed by irradiating the coated film after heating with ultraviolet rays having an integrated light intensity of 300 mJ / cm ^{2 with} a high-pressure mercury lamp. Then, by removing the surface protective film bonded on the first reinforcing film, a flexible polarizing film having reinforcing films on both sides of the polarizer was obtained.

Example 6 (Preparation of Flexible Polarizing Film)
The water-based resin emulsion material (3) of the reinforcing film was applied to the polarizer (first surface) of the polarizer A0 (optical film laminate containing a polarizer having a thickness of 5 μm) obtained above by using a wire bar coater. After coating so that the thickness after curing was 5 μm, it was cured under the conditions of 80 ° C. for 5 minutes to form a first reinforcing film. Next, a surface protective film (manufactured by Nitto Denko, RP301) was attached onto the first reinforcing film, and then the amorphous PET base material of the optical film laminate was peeled off. Then, the water-based resin emulsion material (3) of the reinforcing film is applied to the polarizer (the second surface which is the peeling surface) using a wire bar coater so that the thickness after curing becomes 5 μm, and then 80. It was cured under the conditions of ° C. for 5 minutes to form a second reinforcing film. Then, by removing the surface protective film bonded on the first reinforcing film, a flexible polarizing film having reinforcing films on both sides of the polarizer was obtained.

Comparative Examples 1-3
A polarizing film having reinforcing films on both sides of the polarizing film was produced in the same manner as in Example 1 except that the type of the polarizer and the thickness of the reinforcing film were changed as shown in Table 2.

Comparative Example 4 (Preparation of Single Protective Polarizing Film)
The thickness of the adhesive layer after curing the ultraviolet curable adhesive on the polarizer (first surface) of the polarizer A0 (optical film laminate containing a polarizer having a thickness of 5 μm) obtained above becomes 1 μm. After the protective film (acrylic) was attached, the adhesive was cured by irradiating it with ultraviolet rays as active energy rays. For ultraviolet irradiation, gallium-filled metal halide lamp, irradiation device: Fusion UV Systems, Light HAMMER10 manufactured by Inc., valve: V valve, peak illuminance: 1600 mW / cm ² , cumulative irradiation amount 1000 / mJ / cm ² (wavelength 380 to 440 nm). ), And the illuminance of ultraviolet rays was measured using a Solar-Check system manufactured by Solartell. Next, the amorphous PET base material of the optical film laminate was peeled off to obtain a single-protective polarizing film.

Comparative Example 5
A flexible polarizing film having a second reinforcing film on only one side of the polarizer was produced in the same manner as in Example 1 except that the first reinforcing film was not provided in Example 1.

Comparative Example 6
A flexible polarizing film having the first reinforcing film on only one side of the polarizer was produced in the same manner as in Example 1 except that the second reinforcing film was not provided in Example 1.

Samples were prepared for the flexible polarizing film obtained in the above example, the polarizing film having the reinforcing film obtained in the comparative example, and the one-sided protective polarizing film, and the following evaluation was performed. The results are shown in Table 2. In Comparative Examples 7 to 9, simple substances A0, A1 and B1 of the polarizers were evaluated. Polarizers A0 and A1 having a thin film thickness were brittle, and evaluation by themselves could not be measured except for rigidity. The evaluation was performed under the conditions of 23 ° C. and 65% RH.

<Simple substance transmittance T and degree of polarization P of the polarizer>
The single transmittance T and the degree of polarization P of the obtained polarizing film were measured using a spectral transmittance measuring device with an integrating sphere (Dot-3c of Murakami Color Technology Laboratory).
The degree of polarization P is the transmittance (parallel transmittance: Tp) when two identical polarizing films are overlapped so that their transmission axes are parallel, and the two transmission axes are overlapped so as to be orthogonal to each other. It is obtained by applying the combined transmittance (orthogonal transmittance: Tc) to the following equation. Polarization degree P (%) = {(Tp-Tc) / (Tp + Tc)} ^1/2 × 100
Each transmittance is shown by a Y value adjusted for luminosity factor by a 2 degree field of view (C light source) of JIS Z8701 with 100% of completely polarized light obtained through a Granteller prism.

<Measurement of compressive elastic modulus>
A TI900 TriboIndenter (manufactured by Hisiron) was used for measuring the compressive elastic modulus. The obtained polarizing film with a reinforcing film (polarizing film) was cut into a size of 10 mm × 10 mm, fixed to a support equipped with a TriboIndenter, and the compressive elastic modulus was measured by a nanoindentation method. At that time, the position was adjusted so that the indenter used pushed in the vicinity of the center of the transparent layer. The measurement conditions are shown below.
Indenter used: Berkovic (trigonal pyramid type)
Measurement method: Single push measurement Measurement temperature: 23 ° C
Push-in depth setting: 100 nm

<U-shaped expansion and contraction test>
This was performed using a planar unloaded U-shaped expansion / contraction tester (product name: main body DLDM111LH and jig: planar unloaded U-shaped expansion / contraction test jig) manufactured by Yuasa System Co., Ltd.
Both ends x and y (50 mm) of a rectangular object 1 (sample) of 50 mm (absorption axis direction) x 100 mm (transmission axis direction) are fixed to the support portions 21 and 22 of the testing machine with double-sided tape (not shown). After that, the rectangular object 1 was expanded and contracted so that one side (first surface) of the rectangular object 1 became U-shaped inward under the following conditions, and the rectangular object was bent (bending of the first surface side in the transmission axis direction). .. The state of one process of U-shaped expansion and contraction is shown in FIG. In the U-shaped expansion and contraction, the bending R (bending radius) was set to be 0, and the rectangular object 1 (sample) was bent from the flat state until it touched in the folded state. In the bending, both ends x and y are brought into contact with both ends x and y by the operation of the support portion, and the other parts of the rectangular object 1 (sample) are both outer sides by plate portions 23 and 24 separately installed. The contact was made by sandwiching it with no load.
Further, in the bending due to the expansion and contraction, the other one side (second surface) of the rectangular object was also expanded and contracted inward so as to form a U shape (bending on the second surface side in the transmission axis direction). ).
Further, the bending by the expansion and contraction is performed so that the first surface and the second surface are U-shaped inward even for a rectangular object (sample) of 50 mm (transmission axis direction) × 100 mm (absorption axis direction). The same procedure was performed (bending of the first surface side and the second surface side in the absorption axis direction).
Expansion and contraction speed: 30 rpm
Bending R: 0
Number of expansion and contraction: 100 times The state of the sample in the U-shaped expansion and contraction test was visually evaluated according to the following criteria.
〇: No cracking or light loss occurs in any of the bending of the first surface side and the second surface side in the transmission axis direction and the bending of the first surface side and the second surface side in the absorption axis direction. It was. Moreover, there were no creases left.
X: Cracking or light loss occurred in any of the bending of the first surface side and the second surface side in the transmission axis direction and the bending of the first surface side and the second surface side in the absorption axis direction. Or, a crease was confirmed.

<Twisting test>
This was performed using a planar body no-load twisting tester (product name: main body TCDM111LH and jig: planar no-load twisting test jig) manufactured by Yuasa System Co., Ltd.
After both short sides of a rectangular object 1 (sample) of 100 mm (absorption axis direction) x 150 mm (transmission axis direction) are sandwiched and fixed by the twisting clips 11 and 12 of the testing machine, one short side is clip 12 The clip 11 on the other short side was twisted under the following conditions while being fixed with. The state of twisting is shown in FIG.
Twisting speed: 10 rpm
Twisting angle: 45 degrees Twisting number: 100 times The state of the sample after the twisting test was visually evaluated according to the following criteria.
〇: No cracking or light loss occurred. Moreover, there were no creases left.
Δ: No cracking or light loss occurred. However, creases remained. X: Cracking and light leakage occurred. Moreover, there were creases left.

The cracks, creases, and light escape criteria in the U-shaped expansion and contraction test and twist test are as follows.
A "crack" means that a tear or crack has occurred through a sample (a flexible polarizing film, a polarizing film having a reinforcing film, or all or a part of the layers constituting the single protective polarizing film). Shown.
"Break marks" are formed on the sample (flexible polarizing film, polarizing film having a reinforcing film, or all or a part of the layers constituting the single protective polarizing film) even after the load is removed by bending or local loading. Indicates that there are residual visible traces.
“Light loss” indicates that the polarizer itself is torn or cracked. To check for light leakage, apply the sample after the test (flexible polarizing film, polarizing film with a reinforcing film, or all layers constituting the single protective polarizing film) and other ordinary polarizing films in a cross-nicoled state on both sides of the glass. It was done by pasting it on the surface and letting light from a backlight or the like pass through.

<Bending holding test>
A rectangular object 1 (sample) of 200 mm (absorption axis direction) × 300 mm (transmission axis direction) was placed on a horizontal table 31. Next, after folding the rectangular object 1 in three in the transmission axis direction (semi-major axis direction), a load 32 of 100 g was applied so that a load was applied to the entire upper surface, and the mixture was left for 5 minutes. The bent state is shown in FIG. After that, the load 32 was removed.
Further, the same operation as described above (however, the sample was folded in three in the absorption axis direction (long axis direction)) was performed on a rectangular object (sample) of 200 mm (transmission axis direction) × 300 mm (absorption axis direction). ..
After the folding holding test, visually check whether the sample is in the tri-folded state, and if the tri-folded shape is maintained, return the sample to the original state (flat surface) and visually check according to the following criteria. evaluated. The evaluation was performed three times for each of the samples on the long side in the transmission axis direction and the long side in the absorption axis direction.
〇: In all the samples, the tri-fold shape was maintained and the original state was maintained without cracking (with retention).
X: The tri-fold shape was not retained in any of the samples. Alternatively, the tri-fold shape was retained, but cracks occurred under load (no retention).
The judgment of "cracking" is the same as the U-shaped expansion / contraction test and the twisting test.

<Rigidity test>
No. made by Yasuda Seiki Seisakusho A 476 cantilever type flexibility tester was used. In addition, in this test, in order to eliminate the influence of static electricity, the samples used in the test were appropriately statically eliminated.
A rectangular object 1 (sample) of 50 mm (absorption axis direction) x 150 mm (transmission axis direction) with a flat top (50 mm x 150 mm: the same size as the sample), a 45 ° slope at one end of the long side, and a cross section. Was installed so as to fit on the top surface of the trapezoidal smooth SUS plate base 41 (see FIG. 5). The sample was installed so that there was a slope in the transmission axis direction.
The sample was gently slid and moved to the slope side at an extrusion speed of 10 mm / sec (1). The movement of the sample was stopped at the point where the tip of the sample first touched the slope (2). The distance L (mm) that the sample moved on a flat top was measured.
For a rectangular object (flexible polarizing film sample) of 50 mm (transmission axis direction) x 150 mm (absorption axis direction), the same operation as described above (however, the sample was installed so that there was a slope in the absorption axis direction) was performed. ..
The rigidity (mm) is the shortest linear distance three times for each of the two patterns when the first surface is on the upper side and the second surface is on the upper side for the samples on the long side in the transmission axis direction and the long side in the absorption axis direction. L (mm) was measured (12 samples in total) and used as the arithmetic average value. If there was a sample that could not be measured due to sample deformation or curl in any one or more of the 12 samples. , The sample was judged to be unmeasurable.

<Tensile test>
A sample (a sample of a flexible polarizing film) was prepared by cutting into a predetermined shape of 10 mm (absorption axis direction) × 150 mm (transmission axis direction) with a multipurpose test piece cutting machine (dumbbell).
The sample was subjected to a tensile test at a tensile speed of 50 mm / min using an Autograph AG-IS manufactured by Shimadzu Corporation.
The sample was prepared by fixing both sides in the transmission axis direction to the clamps 51 and 52 (distance 53 between the initial clamps is 50 mm) and pulling one clamp 52 side (see FIG. 6). The point at which the sample started fracture or plastic deformation was evaluated as "tensile strength".
The tensile strength was the arithmetic mean value of the results of three measurements.

1 Flexible polarizing film a Transparent protective film b1 First reinforcing film b2 Second reinforcing film

Claims (17)

The polyvinyl alcohol-based resin has a polyvinyl alcohol-based polarizer having a thickness of 10 μm or less in which the polyvinyl alcohol-based resin is oriented in one direction and iodine or a dichroic dye is adsorbed and oriented on the polyvinyl alcohol-based resin, and the polyvinyl alcohol-based resin is oriented. After performing a U-shaped expansion and contraction test that repeats expansion and contraction in a U-shape in the orientation direction in which the plastic is oriented and in the direction orthogonal to the orientation direction, there are no cracks, creases, or light leakage in either direction. Flexible polarizing film. The flexible polarizing film according to claim 1, wherein there are no cracks, creases, or light leakage after a twisting test in which the polyvinyl alcohol-based resin is twisted in the orientation direction. After performing a bending holding test in which the polyvinyl alcohol-based resin is bent and held in the orientation direction in which the polyvinyl alcohol-based resin is oriented and in a direction orthogonal to the orientation direction, the bent shape is maintained and cracks occur in either direction. The flexible polarizing film according to claim 1 or 2, wherein the flexible polarizing film is not provided. Any of claims 1 to 3 characterized in that the rigidity (mm) is 60 mm or less in the rigidity test in the orientation direction in which the polyvinyl alcohol-based resin is oriented and in the direction orthogonal to the orientation direction. The flexible polarizing film described in. The flexible polarizing film according to any one of claims 1 to 4, wherein in the tensile test, the tensile strength in the direction orthogonal to the orientation direction in which the polyvinyl alcohol-based resin is oriented is 5 N / 10 mm or more. The polyvinyl alcohol-based polarizer has optical characteristics represented by a simple substance transmittance T and a degree of polarization P of the following formula P>-(10 ^{0.929T-42.4-1} ) × 100 (where T <42. 3) or
The flexible polarizing film according to any one of claims 1 to 5, wherein the flexible polarizing film is configured to satisfy the condition of P ≧ 99.9 (however, T ≧ 42.3). The flexible polarizing film according to any one of claims 1 to 6, wherein a reinforcing film in close contact with the polyvinyl alcohol-based polarizer is provided on both sides of the polyvinyl alcohol-based polarizer. The flexible polarizing film according to claim 7, wherein the reinforcing film on at least one surface has a thickness of 15 μm or less. 8. The eighth aspect of the present invention, wherein the first one side of the polyvinyl alcohol-based polarizer has a first reinforcing film having a thickness of 15 μm or less, and the other second side has a second reinforcing film having a thickness of 15 μm or less. Flexible polarizing film. The flexible polarizing film according to claim 9, wherein the thickness difference between the first reinforcing film and the second reinforcing film is 10 μm or less. The flexible polarizing film according to any one of claims 7 to 10, wherein the ratio of the thickness of the reinforcing film to the thickness of the polyvinyl alcohol-based polarizer is 0.4 or more. The flexible polarizing film according to any one of claims 7 to 11, wherein the reinforcing film has a compressive elastic modulus at 23 ° C. of 1 MPa or more. The flexible polarizing film according to any one of claims 7 to 12, wherein the reinforcing film is not substantially oriented. The flexible polarizing film according to any one of claims 7 to 13, wherein the reinforcing film is a resin film. The flexible polarizing film according to claim 14, wherein the resin film is a product of a thermosetting resin or an active energy ray-curable resin. The method for producing a flexible polarizing film according to claim 14 or 15.
Step (1) of preparing a polyvinyl alcohol-based polarizer having a thickness of 10 μm or less, in which the polyvinyl alcohol-based resin is oriented in one direction and iodine or a dichroic dye is adsorbed and oriented on the polyvinyl alcohol-based resin.
A reinforcing film is formed by applying a liquid material containing a resin component or a curable component capable of forming a resin film on both sides of the polyvinyl alcohol-based polarizer, and then solidifying or curing the liquid material. A method for producing a flexible polarizing film, which comprises the step (2) of forming. An image display device having the flexible polarizing film according to any one of claims 1 to 15.

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