KR102219925B1 - Flexible polarizing film, manufacturing method thereof, and image display device - Google Patents

Abstract

The present invention has a polyvinyl alcohol-based polarizer having a thickness of 10 μm or less formed by adsorbing and orienting a polyvinyl alcohol-based resin in one direction and iodine or a dichroic dye on the polyvinyl alcohol-based resin, and the polyvinyl alcohol-based resin It is a flexible polarizing film characterized in that there are no cracks, creases, and light leakage after performing a twist test in which the vinyl alcohol-based resin is twisted in the orientation direction in which it is oriented. The flexible polarizing film of the present invention has a high degree of flexibility (flexibility) despite the use of a polyvinyl alcohol-based polarizer.

Description

Flexible polarizing film, manufacturing method thereof, and image display device

The present invention relates to a flexible polarizing film and a method of manufacturing the same. The flexible polarizing film may be used alone or as an optical film laminated thereon to form an image display device such as a liquid crystal display (LCD) or an organic EL display.

In a liquid crystal display device, it is indispensable to arrange polarizers on both sides of the glass substrate forming the liquid crystal panel surface from the image forming method. As a polarizer, a polyvinyl alcohol-based polarizer is generally used in which a polyvinyl alcohol-based resin is oriented in one direction, and iodine or a dichroic dye is adsorbed and oriented to the polyvinyl alcohol-based resin. . However, polyvinyl alcohol-based polarizers have a problem in that they are easily fragile and torn by themselves. In particular, the polyvinyl alcohol-based polarizer is easily torn in parallel in the direction in which the polyvinyl alcohol-based resin is oriented (the direction of the absorption axis), and, for example, it is very easily torn when an external force to shrink in the direction of the absorption axis is applied.

Therefore, it is common that a polyvinyl alcohol-based polarizer is used as a polarizing film obtained by bonding a transparent protective film on one or both sides thereof.

As other polarizers, grid polarizers other than polyvinyl alcohol polarizers are known (Patent Documents 1 and 2).

Japanese Patent Laid-Open Publication No. 2005-316495 Japanese Unexamined Patent Publication No. 2007-232792

However, a general polarizing film using a polyvinyl alcohol-based polarizer has rigidity (elasticity) and lacks flexibility (flexibility) because a transparent protective film is attached thereto. Therefore, when twisting is applied to the polarizing film, the use of the polarizing film is restricted due to the occurrence of cracks, fold marks (fold marks), and light leakage in the polarizer. 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 manufacturing 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.

The inventors of the present application found that the above problems can be solved by the following flexible polarizing films or the like as a result of intensive examination and came to the present invention.

That is, the present invention has a polyvinyl alcohol-based polarizer having a thickness of 10 μm or less obtained by adsorbing and orienting a polyvinyl alcohol-based resin in one direction and iodine or a dichroic dye to the polyvinyl alcohol-based resin. It relates to a flexible polarizing film, characterized in that there are no cracks, creases, and leakage of light after performing a twist (salt ash) test in which the polyvinyl alcohol-based resin is twisted in the orientation direction.

In the flexible polarizing film, after performing a U-shaped stretching test in which the polyvinyl alcohol-based resin is oriented and stretched in a U-shape in a direction orthogonal to the orientation direction, cracking in any direction It is preferable that there are no folds and leakage of light.

In the flexible polarizing film, after performing a bending maintenance test in which the polyvinyl alcohol-based resin is bent and held in an orientation direction in which the polyvinyl alcohol-based resin is oriented and a direction orthogonal to the orientation direction, the bending shape is maintained in any direction. At the same time, it is desirable that no cracking occurs.

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

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

In the flexible polarizing film, the polyvinyl alcohol-based polarizer has optical properties represented by a single transmittance (T) and a polarization degree (P), by the following formula:

P>-(10 ^0.929T-42.4 -1)×100 (however, T<42.3), or

It is preferable to be configured to satisfy the condition of P≥99.9 (however, T≥42.3).

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

In the flexible polarizing film, it is preferable to have a first reinforcing film having a thickness of 15 μm or less on a first side of the polyvinyl alcohol-based polarizer and a second reinforcing film having a thickness of 15 μm or less on the other second side of the polyvinyl alcohol polarizer. It is preferable that the thickness difference between the first reinforcing layer and the second reinforcing layer is 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 modulus of 1 MPa or more at 23°C.

In the flexible polarizing layer, the reinforcing layer may be substantially unoriented.

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

In addition, the present invention is a method of manufacturing the flexible polarizing film,

Step (1) of preparing a polyvinyl alcohol-based polarizer having a thickness of 10 μm or less obtained by adsorbing orienting a polyvinyl alcohol-based resin in one direction and iodine or a dichroic dye on the polyvinyl alcohol-based resin,

A step of forming a reinforcing film by coating a liquid material containing a resin component or a curable component capable of constituting a resin film on at least one side of the polyvinyl alcohol polarizer, and then solidifying or curing the liquid material (2) It relates to a method of manufacturing a flexible polarizing film comprising ).

Further, the present invention 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 has a thickness of 10 µm or less, and is also preferable in terms of being thinner.

In addition, the flexible polarizing film of the present invention has a high degree of flexibility despite the fact that the polyvinyl alcohol polarizer is used as a simple substance, and even when the shape is deformed by applying a twist, a crack may occur in the entire film or Folded marks (folded marks) are not left or light leakage does not occur in the polarizer. In addition, the flexible polarizing film of the present invention may have flexibility for various deformations such as stretching and bending. As described above, the flexible polarizing film of the present invention has the flexibility of the polarizing film itself, and the tensile rupture stress of a conventional polyvinyl alcohol polarizer is remarkably small, so that it is practically impossible to handle. great.

In addition, the flexible polarizing film of the present invention has flexibility when used in combination with or in combination with other members by utilizing flexibility, and cracks of the polarizer can be suppressed, and can be used for various purposes. Accordingly, the use of the flexible polarizing film is greatly expanded due to the expansion of the application to a single flexible polarizing film or the expansion of the allowance in the process. Therefore, the flexible polarizing film of the present invention can cope with a design that could not be applied as a replacement for a polarizer, for example, because it was soft and easily torn by a conventional polarizer, and a polarizing film (a transparent protective film provided on the polarizer As an alternative to ), for example, it is possible to cope with various deformed shapes that could not be applied due to the rigidity of the conventional polarizing film, and it is possible to expand application development.

1 is an example of a schematic cross-sectional view of a flexible polarizing film of the present invention.
2 is a schematic diagram showing a state of torsion in a torsion test.
Fig. 3 is a schematic diagram showing a state of a U-shape in a U-shape stretch test.
4 is a schematic diagram showing a bending state in a bending holding test.
5 is a schematic diagram showing the degree of stiffness in a stiffness test.
6 is a schematic diagram showing a tensile test.

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

<Polyvinyl alcohol polarizer>

The polyvinyl alcohol-based polarizer is formed by oriented polyvinyl alcohol-based resin in one direction (absorption axis direction) and iodine or dichroic dye adsorbed and aligned to the polyvinyl alcohol-based resin. Examples of the polyvinyl alcohol resin include polyvinyl alcohol, partially formalized polyvinyl alcohol, and partially saponified ethylene/vinyl acetate copolymer. The polarizer can be obtained by uniaxial stretching by adsorbing a dichroic dye of iodine or a dichroic dye to a polyvinyl alcohol-based film using the polyvinyl alcohol-based resin.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine or a dichroic dye and uniaxially stretched can be produced by, for example, dyeing by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching to 3 to 7 times the original length. If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, and may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, before dyeing, the polyvinyl alcohol-based film may be immersed in water and washed with water. By washing the polyvinyl alcohol-based film with water, it is possible to wash the surface of the polyvinyl alcohol-based film with an anti-contamination or blocking agent, and by expanding the polyvinyl alcohol-based film, there is an effect of preventing unevenness such as staining of dyeing. Stretching may be performed after dyeing with iodine or a dichroic dye, or stretching may be performed while dyeing, or may be dyed with iodine or a dichroic dye after stretching. It can also be stretched in an aqueous solution such as boric acid or potassium iodide or in a water bath.

The polyvinyl alcohol polarizer containing boric acid is preferable from the viewpoint of stretching stability and optical durability. In addition, the content of boric acid contained in the polarizer is preferably 25% by weight or less, further preferably 20% by weight or less, further 18% by weight or less, further 16% by weight, based on the total amount of the polarizer from the viewpoint of suppressing the occurrence of leakage light. It is preferable that it is the following. 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, and further preferably 12% by weight or more.

In the present invention, a polyvinyl alcohol polarizer having a thickness of 10 μm or less is used. When the thickness of the polyvinyl alcohol polarizer exceeds 10 µm, it is difficult to obtain sufficient flexibility. The thickness of the polarizer is preferably 8 µm or less, further preferably 7 µm or less, and further 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, and further 3 µm or more. Such a thin polarizer is excellent in durability against thermal shock because it has little thickness unevenness, excellent visibility, and little dimensional change.

As a thin polarizer, representatively, Japanese Patent No. 4771486 Specification, Japanese Patent No. 44751481 Specification, Japanese Patent No. 4815544 Specification, Japanese Patent No. 5048120 Specification, International Publication No. 2014/077599 Pamphlet, International Publication No. 2014/077636 The thin polarizer described in the pamphlet or the like or the thin polarizer obtained from the manufacturing method described therein may be mentioned.

The polarizer has an optical characteristic represented by a single transmittance (T) and a polarization degree (P) in the following formula: P>-(10 ^0.929T-42.4 -1)×100 (however, T<42.3), or P≥99.9 (However, it is configured to satisfy the condition of T≥42.3). The polarizer configured to satisfy the above condition has a performance required as a display for a liquid crystal TV using a large display element, in a sense. Specifically, it has a contrast ratio of 1000:1 or more and a maximum luminance of 500 cd/m2 or more. As another application, for example, it is pasted on the viewer side of an organic EL display device.

On the other hand, the polarizer configured to satisfy the above conditions has a thickness of 10 μm or less, and a direction perpendicular to the direction of the absorption axis of the polarizer (transmission axis) because the constituting polymer (for example, polyvinyl alcohol-based molecule) exhibits high orientation. Direction), the tensile breaking stress becomes remarkably small. As a result, for example, in a general polarizing film, the possibility that light leakage occurs in the direction of the absorption axis of the polarizer is extremely high. The flexible polarizing film of the present invention has excellent flexibility despite the use of a polyvinyl alcohol-based polarizer that is weak against impacts having a thickness of 10 μm or less.

As the thin polarizer, among the manufacturing methods including the step of stretching and dyeing in the state of a laminate, it can be stretched at a high magnification and thus the polarization performance can be improved. , It is preferably obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in the specification of Japanese Patent No. 4815544, and in particular, in an aqueous boric acid solution described in the specification of Japanese Patent No. 44751481 and Specification of Japanese Patent No. 4815544. It is preferably obtained by a manufacturing method including a step of auxiliary aerial stretching before stretching. These thin polarizers can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin (hereinafter, also referred to as a PVA-based resin) layer and a resin substrate for stretching in a laminated state and a step of dyeing. In this manufacturing method, even if the PVA-based resin layer is thin, it is supported by the resin substrate for stretching, so that it is possible to stretch without problems such as fracture due to stretching.

The flexible polarizing film of the present invention is specifically characterized in that the polyvinyl alcohol-based polarizer does not have cracks, creases, and leakage of light after performing the torsion test shown in Examples. The torsion test is an index showing the flexibility in a twisted state in the orientation direction (absorption axis direction) in which the polyvinyl alcohol-based resin, which tends to generate cracks, creases, and leakage, is oriented. It can be seen that the flexible polarizing film of the present invention does not generate cracks, folds, and leaks in the torsion test, and has excellent flexibility in a twisted state.

In addition, it is preferable that the flexible polarizing film of the present invention can suppress the occurrence of cracks, creases, and leakage of light after specifically performing the U-shaped stretching test shown in Examples. The U-shaped stretch test is an index showing the flexibility related to the bendability under no load in the U-shape in the orientation direction (absorption axis direction) and the orthogonal direction (transmission axis direction) in which the polyvinyl alcohol-based resin is oriented. It can be seen that the flexible polarizing film of the present invention suppresses the occurrence of cracks, folds, and leakage of light in the U-shaped stretch test, so that it has excellent flexibility related to bendability at no load in either direction of the absorption axis and the transmission axis. have.

In addition, it is preferable that the flexible polarizing film of the present invention maintains the bent shape and suppresses cracking at the same time after performing the bending maintenance test shown in the examples. In the bending maintenance test, even when the polyvinyl alcohol-based resin is bent in the orientation direction (absorption axis direction) and its orthogonal direction (transmission axis direction) and placed in a bent state, the flexible polarizing film can maintain its original shape. It is an indicator of flexibility related to maintainability. It can be seen that the flexible polarizing film of the present invention maintains the bending shape in the bending maintenance test and suppresses cracking, and thus has excellent retention in both the absorption axis direction and the transmission axis direction.

In addition, it is preferable that the flexible polarizing film of the present invention has a stiffness (mm) of 60 mm or less in the stiffness test specifically shown in Examples. The stiffness test is an index showing flexibility related to the bending followability (low resistance to bending) in the orientation direction (absorption axis direction) in which the polyvinyl alcohol-based resin is oriented and its orthogonal direction (transmission axis direction). It can be seen that the flexible polarizing film of the present invention has the stiffness of 60 mm or less, and has flexibility related to bending followability (low resistance to bending). Further, the stiffness (mm) is an index indicating the flexibility, and is preferably 50 mm or less, and further preferably 40 mm or less. On the other hand, there is no particular limitation on the lower limit of the strength (mm).

In addition, it is preferable that the flexible polarizing film of the present invention has a tensile strength of 5 N/10 mm or more in a tensile test specifically shown in Examples. The tensile test is an index showing the strength in a direction (transmission axis direction) orthogonal to the orientation direction (absorption axis direction) in which the polyvinyl alcohol-based resin is oriented. It can be seen that the flexible polarizing film of the present invention has strength in the direction of the transmission axis by satisfying the tensile strength of 5N/10mm or more. In addition, the tensile strength is preferably 7N/10mm or more, further preferably 10N/10mm or more from the viewpoint of strength.

Hereinafter, an example of the flexible polarizing film of the present invention will be described with reference to FIG. 1.

As the flexible polarizing film of the present invention, for example, one having a reinforcing film on at least one side of a polyvinyl alcohol-based polarizer can be used. The flexible polarizing film 1 of FIG. 1A is a case in which the first reinforcing film b1 is provided only on the first side of the polyvinyl alcohol-based polarizer a. In addition, the flexible polarizing film 1 of FIG. 1(B) has a first reinforcing film b1 on the first one side of the polyvinyl alcohol-based polarizer 1, and a second reinforcing film (b1) on the second one side of the other side. b2). In the flexible polarizing film 1 of the present invention, the first reinforcing film b1 and/or the second reinforcing film b2 is provided directly on the polyvinyl alcohol-based polarizer 1.

The flexible polarizing film 1 of the present invention has flexibility in the torsion test, and has a transparent protective film on one or both sides of a polyvinyl alcohol polarizer (a), and a general polarizing film that cannot satisfy the flexibility. It is clearly distinguished from.

<Reinforcement membrane>

The thickness of the reinforcing film is preferably 15 µm or less, further 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, further preferably 3 µm or more, further preferably 5 µm or more from the viewpoint of flexibility and strength.

In addition, the ratio (t2/t1) of the thickness (t2) of the reinforcing film to the thickness (t1) of the polyvinyl alcohol polarizer is preferably 0.4 or more from the viewpoint of flexibility and strength, further preferably 0.6 or more, and further 0.8 It is preferable that it is above. On the other hand, the ratio (t2/t1) is preferably 2.0 or less, further preferably 1.5 or less, and further preferably 1.2 or less from the viewpoint of thinning.

The reinforcing film is a polyvinyl alcohol-based polarizer, as shown in Fig. 1 (B), rather than having the first reinforcing film (b1) only on one side of the polyvinyl alcohol-based polarizer 1, as shown in Fig. 1(A). In the case of having the first reinforcing film (b1) and the second reinforcing film (b2) on both sides of (1), the flexibility in the torsion test, U-shaped stretch test, etc. can be more satisfied, and the strength in the tensile test is increased. It is preferable in that it can be satisfied.

In the case of having the first reinforcing film (b1) and the second reinforcing film (b2) on both sides of the polyvinyl alcohol-based polarizer 1 as shown in FIG. 1(B), the thickness of each reinforcing film may be the same or different. However, the difference in the thickness of the first reinforcing film (b1) and the second reinforcing film (b2) is normal (a state in which only the flexible polarizing film is left alone) and in a flexibility test (various tests such as a twist test). From the viewpoint of uniform (symmetrical) stress in the flexible polarizing film and easy to secure strength and flexibility, it is preferably 10 μm or less, further preferably 7 μm or less, further preferably 5 μm or less, and particularly the same thickness. desirable.

It is preferable from the viewpoint of strength that the reinforcing film has a compressive elastic modulus of 1 MPa or more at 23°C. Further, the compressive modulus of the reinforcing film is preferably 10 MPa or more, and further preferably 100 MPa or more. On the other hand, when the compressive elastic modulus of the reinforcing film layer is increased, the compressive elastic modulus is preferably 10 GPa or less, and further preferably 1 GPa or less, since it tends to become too stiff and poor flexibility.

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, and can also be formed by depositing an inorganic oxide such as _{SiO 2 on a polyvinyl alcohol-based polarizer by a sputtering method or the like.} It is preferable that the reinforcing film is a resin film formed of a resin material from the viewpoint of simply forming.

The reinforcing film may or may not be oriented, and either of them may be used. When the reinforcing film is oriented, a phase difference occurs and the optical properties of the polyvinyl alcohol-based polarizer change. Therefore, when the optical properties of the polarizer are maintained, it is preferable that the reinforcing film is not substantially oriented. The fact that the reinforcing layer is not substantially aligned means that the alignment exists inside the reinforcing layer due to the orientation of the polarizer, but the treatment for actively aligning the reinforcing layer is not performed. A reinforcing film that is not substantially oriented can be formed, for example, by applying a material for forming a resin film to a polyvinyl alcohol-based polarizer. On the other hand, what is oriented as the reinforcing film can be used. The oriented reinforcing film has 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 being in close contact with a polyvinyl alcohol-based polarizer, and for example, a polyester-based resin, a polyether-based resin, a polycarbonate-based resin, a polyurethane-based resin, a silicone-based resin, And polyamide resins, polyimide resins, PVA resins, acrylic resins, and epoxy resins. These resin materials may be used alone or in combination of two or more, but among them, at least one selected from the group consisting of polyurethane-based resins, PVA-based resins, acrylic resins, and epoxy resins is preferable. Resin and acrylic resin are more preferable.

The reinforcing film can be formed by coating a liquid product including the surface of the polarizer, the resin component, or a curable component capable of constituting the resin, and then solidifying or curing the liquid product. In addition, the form of the coating liquid, which is a liquid, is not particularly limited as long as it represents a liquid, and any of aqueous, water-dispersible, solvent, and non-solvent may be used.

In addition, the forming material may contain an additive within a range that does not impair the function of the reinforcing film. For example, silane coupling agents, polyether compounds of polyalkylene glycol such as polypropylene glycol, powders such as colorants, pigments, dyes, surfactants, plasticizers, tackifiers, antistatic agents, surface lubricants, leveling agents, softeners, Antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, thin materials, etc. can be appropriately added depending on the intended use. Further, a redox system to which a reducing agent is added within a controllable range may be employed.

The liquid material (coating solution) is advantageous if the viscosity is low. The viscosity, as measured at 25°C, is preferably 2000 mPa·s or less, further preferably 1000 mPa·s or less, further preferably 500 mPa·s or less, and further preferably 100 mPa·s or less.

In the formation of the reinforcing film, after the liquid material containing the resin component is applied, the resin component is solidified according to the type. The liquid substance containing the resin component is a solution or dispersion obtained by dissolving the resin component in a solvent, and is used, for example, as an aqueous solution, an aqueous dispersion, or a solvent-based solution. The solidification refers to forming a resin layer by removing a solvent from the liquid.

An aqueous resin emulsion can be used as the aqueous dispersion liquid. The aqueous resin emulsion is one containing 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 resins, silicone resins, polyurethane resins, and fluorine resins. Among these, in the present invention, polyurethane resins and acrylic resins are preferable because of excellent optical transparency and excellent weather resistance and heat resistance.

As the water-based resin emulsion, for example, a brand name manufactured by Taisei Fine Chemicals: SE-2915E (acrylic emulsion containing a UV absorber), and a brand name manufactured by Toagosei: Aaron A-104, Aaron A-106, and the like can be mentioned. have.

Meanwhile, in the formation of the transparent resin layer, after coating a liquid product containing a curable component capable of constituting the resin, curing is performed so that the curable component can form a resin according to the type of the curable component. . A liquid product containing a curable component capable of constituting the resin can be used in a solvent-free system as long as the curable component represents a liquid product. In addition, the liquid material may be a solution in which the curable component is dissolved in a solvent. Further, even when the curable component represents a liquid, it can be used as a solution. As the solvent, it can be appropriately selected depending on the curable component to be 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, an active energy ray irradiation (ultraviolet irradiation) to a liquid product containing the curable component Hardening by etc. can be performed.

With respect to the reinforcing film, a curable forming material containing a curable component capable of constituting a resin will be described. As the curable component, it can be broadly classified into an active energy ray curing type such as an electron beam curing type, an ultraviolet curing type, and a visible ray curing type and a thermal curing type. In addition, the ultraviolet curing type and the visible ray curing type can be classified into a radical polymerization curing type and a cationic polymerization curing 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 rays. The radical polymerization curable curable component can be used as a thermosetting curable component.

≪Radical polymerization curable forming material≫

As said curable component, a radical polymerizable compound is mentioned, for example. The radical polymerizable compound includes a compound having a radically polymerizable functional group of a carbon-carbon double bond such as a (meth)acryloyl group and a vinyl group. As for 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 radical polymerizable compounds, compounds having a (meth)acryloyl group are preferable, for example. In addition, in the present invention, (meth)acryloyl means an acryloyl group and/or a methacryloyl group, and "(meth)" has the same meaning as follows.

<< monofunctional radical polymerizable compound >>

As a monofunctional radical polymerizable compound, a (meth)acrylamide derivative which has a (meth)acrylamide group is mentioned, for example. The (meth)acrylamide derivative is preferred in that it secures adhesion to a polarizer and also has a high polymerization rate and is excellent in productivity. Specific examples of the (meth)acrylamide derivative include, for example, N-methyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, and N-isopropyl ( N-alkyl group-containing (meth)acrylamide derivatives such as meth)acrylamide, N-butyl (meth)acrylamide, and N-hexyl (meth)acrylamide; N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as N-methylol (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, and N-methylol-N-propane (meth)acrylamide; N-aminoalkyl group-containing (meth)acrylamide derivatives such as aminomethyl (meth)acrylamide and aminoethyl (meth)acrylamide; N-alkoxy group-containing (meth)acrylamide derivatives such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide; N-mercaptoalkyl group-containing (meth)acrylamide derivatives such as mercaptomethyl (meth)acrylamide and mercaptoethyl (meth)acrylamide; And the like. In addition, as a heterocycle-containing (meth)acrylamide derivative in which the nitrogen atom of the (meth)acrylamide group forms a heterocycle, for example, N-acryloylmorpholine, N-acryloylpiperidine, N-metha Acryloyl piperidine, N-acryloyl pyrrolidine, and the like.

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

Moreover, as a monofunctional radical polymerizable compound, various (meth)acrylic acid derivatives which have a (meth)acryloyloxy group are mentioned, for example. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylic Rate, n-butyl (meth)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 , (Meth)acrylic acid (carbon number 1-20) alkyl esters such as 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate Can be mentioned.

In addition, examples of the (meth)acrylic acid derivative include cycloalkyl (meth)acrylates 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 Polycyclic (meth)acrylates such as (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and dicyclopentanyl (meth)acrylate;

2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethylcarbitol ( Alkoxy group or phenoxy group-containing (meth)acrylates such as meth)acrylate, phenoxyethyl (meth)acrylate, and alkylphenoxypolyethylene glycol (meth)acrylate; And the like.

In addition, examples of the (meth)acrylic acid derivative include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. )Acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12- Hydroxyalkyl(meth)acrylates such as hydroxylauryl(meth)acrylate, [4-(hydroxymethyl)cyclohexyl]methylacrylate, cyclohexane dimethanolmono(meth)acrylate, 2-hydro Hydroxyl group-containing (meth)acrylates such as oxy-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-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth) Halogen-containing (meth)acrylates such as acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate;

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) ) Oxetane group-containing (meth)acrylates such as acrylate and 3-hexyl-oxetanylmethyl (meth)acrylate;

(Meth) acrylates having heterocycles such as tetrahydrofurfuryl (meth) acrylate, butyrolactone (meth) acrylate, hydroxypivalic acid neopentyl glycol (meth) acrylic acid adduct, p-phenylphenol ( And meth)acrylate.

Further, examples of the monofunctional radical 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.

Further, examples of the monofunctional radical polymerizable compound include lactam vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; Vinyl-based monomers having nitrogen-containing heterocycles such as vinylpyridine, vinylpiperidine, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine. .

Further, as the monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group can be used. The radically polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth)acryl group at the terminal or in the molecule and further having an active methylene group. As an active methylene group, an acetoacetyl group, an alkoxymalonyl group, a cyanoacetyl group, etc. are mentioned, for example. It is preferable that the active methylene group is an acetoacetyl group. Specific examples of the radical polymerizable compound having an active methylene group include, for example, 2-acetoacetoxyethyl (meth)acrylate, 2-acetoacetoxypropyl (meth)acrylate, and 2-acetoacetoxy-1-methylethyl ( Acetoacetoxyalkyl (meth)acrylate such as meth)acrylate; 2-Ethoxymalonyloxyethyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxy Butyl)acrylamide, N-(4-acetoacetoxymethylbenzyl)acrylamide, N-(2-acetoacetylaminoethyl)acrylamide, and the like. The radically polymerizable compound having an active methylene group is preferably acetoacetoxyalkyl (meth)acrylate.

≪Multifunctional radical polymerizable compound≫

In addition, as a bifunctional or higher polyfunctional radical polymerizable compound, for example, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 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, tricyclodecane Dimethanol di(meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, dioxane glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate , Pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, EO-modified diglycerin tetra (meth) acrylate and other (meth) acrylic acids An esterified product with a polyhydric alcohol, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene is mentioned. Specific examples include Aronix M-220, M-306 (manufactured by Toagosei), light acrylate 1,9ND-A (manufactured by Kyoa Chemical), light acrylate DGE-4A (manufactured by Kyoa Chemical), light acrylate DCP-A (manufactured by Kyoa Chemical), SR-531 (manufactured by Sartomer), CD-536 (manufactured by Sartomer), and the like. Moreover, various types of epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, and various (meth)acrylate-based monomers may be mentioned as needed.

As for the radical polymerizable compound, it is preferable to use a monofunctional radical polymerizable compound and a polyfunctional radical polymerizable compound together from the viewpoint of making the adhesiveness with a polarizer and optical durability compatible. Usually, it is preferable to use it together in the ratio of 3 to 80 weight% of a monofunctional radically polymerizable compound and 20 to 97 weight% of a polyfunctional radically polymerizable compound with respect to 100 weight% of a radical polymerizable compound.

≪Mode of radical polymerization curable forming material≫

The radical polymerization curable forming material can be used as an active energy ray-curable or thermally curable forming material. When an electron beam or the like is used for an active energy ray, the active energy ray-curable forming material does not need to contain a photopolymerization initiator, but when an ultraviolet ray or visible ray is used for an active energy ray, it is preferable to contain a photopolymerization initiator. On the other hand, when the curable component is used as a thermosetting component, it is preferable that the forming material contains a thermal polymerization initiator.

≪Photo polymerization initiator≫

In the case of using a radical polymerizable compound, the photopolymerization initiator is appropriately selected by active energy rays. In the case of curing by ultraviolet or visible light, a photopolymerization initiator of ultraviolet or visible light cleavage 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-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, α -Aromatic ketone compounds such as hydroxycyclohexylphenyl ketone; Methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane Acetophenone compounds such as -1; Benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether; Aromatic ketal compounds such as benzyl dimethyl ketal; Aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; Photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; Thioxanthone, 2-chloro thioxanthone, 2-methyl thioxanthone, 2,4-dimethyl thioxanthone, isopropyl thioxanthone, 2,4-dichloro thioxanthone, 2,4-diethyl thioxanthone Thioxanthone compounds such as santon, 2,4-diisopropyl thioxanthone, and dodecyl thioxanthone; Camphorquinone; Halogenated ketones; Acylphosphine oxide; Acyl phosphonate, etc. are mentioned.

The blending amount of the photopolymerization initiator is 20 parts by weight or less based on 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, further preferably 0.05 to 10 parts by weight, further preferably 0.1 to 5 parts by weight.

In the case of using the curable forming material as a visible light curing type containing a radical polymerizable compound as a curable component, it is particularly preferable to use a photopolymerization initiator that is highly sensitive to light of 380 nm or more. A photoinitiator that is highly sensitive to light of 380 nm or more will be described later.

Examples of the photopolymerization initiator include compounds represented by the following general formula (1);

[Formula (1)]

(Wherein, R ¹ and R ² represent -H, -CH ₂ CH ₃ , -iPr or Cl, and R ¹ and R ² may be the same or different), or the formula (1) It is preferable to use the compound represented by and a photoinitiator with high sensitivity to light of 380 nm or more to be described later. When the compound represented by the formula (1) is used, adhesion is excellent compared to 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 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 formula (1) in the forming material is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, and more preferably 0.9 to 3 parts by weight based on 100 parts by weight of the total amount of the curable component. It is more preferable to deny it.

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

Moreover, a known photoinitiator can be used together as needed. As a photoinitiator, it is preferable to use a photoinitiator which is highly sensitive to light of 380 nm or more. Specifically, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-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-cyclopentadien-1-yl)-bis(2,6-difluoro -3-(1H-pyrrol-1-yl)-phenyl) titanium and the like.

In particular, as a photoinitiator, in addition to the photoinitiator of formula (1), a compound further represented by the following formula (2);

[Formula (2)]

(In the formula, R ³ , R ⁴ and R ⁵ represent -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. As the compound represented by the formula (2), 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (brand name: IRGACURE907, manufacturer: BASF), which is also a commercial product, is preferably used. It is possible. 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 (brand name: IRGACURE379, manufacturer: BASF) is preferable because of its high sensitivity.

<Radically polymerizable compound having an active methylene group and radical polymerization initiator with hydrogen abstraction>

In the above active energy ray-curable forming material, when a radical polymerizable compound having an active methylene group is used as the radical polymerizable compound, it is preferably used in combination with a radical polymerization initiator having a hydrogen extraction function.

Examples of the radical polymerization initiator having a hydrogen drawing action include a thioxanthone radical polymerization initiator, a benzophenone radical polymerization initiator, and the like. The radical polymerization initiator is preferably a thioxanthone radical polymerization initiator. Examples of the thioxanthone radical polymerization initiator include compounds represented by the general formula (1). Specific examples of the compound represented by the general formula (1) include thioxanthone, dimethyl thioxanthone, diethyl thioxanthone, isopropyl thioxanthone, and chloro thioxanthone. Among the compounds represented by the formula (1), diethylthioxanthone in which ^{R 1} and R ² are -CH ₂ CH _{3 is particularly preferable.}

In the case where the active energy ray-curable forming material contains a radically polymerizable compound having an active methylene group and a radical polymerization initiator having a hydrogen drawing action, the active methylene group is obtained when the total amount of the curable component is 100% by weight. It is preferable to contain 1 to 50 parts by weight of the radical polymerizable compound and 0.1 to 10 parts by weight of the radical polymerization initiator based on 100 parts by weight of the total amount of the curable component.

≪Thermal polymerization initiator≫

As a thermal polymerization initiator, it is preferable that polymerization does not start by thermal cleavage when forming a reinforcing film. For example, as a thermal polymerization initiator, it is preferable that the 10-hour half-life temperature is 65 degreeC or more, and further 75-90 degreeC. In addition, this half-life is an index showing the decomposition rate of the polymerization initiator, and refers to the time until the residual amount of the polymerization initiator becomes half. The decomposition temperature for obtaining a half-life at an arbitrary time or the half-life at an arbitrary temperature is described in the manufacturer's catalog, for example, "Organic Peroxide Catalog 9th Edition (May 2003) of Nippon Yushi Co., Ltd." And the like.

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), 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-hexylperoxypivalate, t-butylperoxy Pivalate, dilauroyl peroxide (10 hours half-life temperature: 64°C), di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (10 hours Half-life temperature: 66°C), di(4-methylbenzoyl)peroxide, dibenzoyl peroxide (10 hour half-life temperature: 73°C), t-butylperoxyisobutyrate (10 hour half-life temperature: 81°C), 1, Organic peroxides, such as 1-di(t-hexylperoxy)cyclohexane, are mentioned.

In addition, as the thermal polymerization initiator, for example, 2,2'-azobisisobutyronitrile (10 hour half-life temperature: 67°C), 2,2'-azobis(2-methylbutyronitrile) (10 hour half-life Temperature: 67°C), 1,1-azobis-cyclohexane-1-carbonitrile (10 hour half-life temperature: 87°C), and other azo compounds.

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

≪Cationic polymerization curable forming material≫

Examples of the curable component of the cationic polymerization curable forming material include compounds having an epoxy group or 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. As a preferred epoxy compound, a compound having at least two epoxy groups and at least one aromatic ring in the molecule (aromatic epoxy compound), or a compound having at least two epoxy groups in the molecule, and at least one of which is adjacent to 2 constituting an alicyclic ring And compounds (alicyclic epoxy compounds) formed between two carbon atoms.

≪Photo cationic polymerization initiator≫

The cationic polymerization curable forming material contains the above-described epoxy compound and oxetane compound as a curable component, and both of these are cured by cationic polymerization, and thus a photocationic polymerization initiator is blended. This photo cationic 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 to initiate a polymerization reaction of an epoxy group or an oxetanyl group.

<Other ingredients>

It is preferable that the curable forming material according to the present invention contains the following components.

<Acrylic oligomer>

The active energy ray-curable forming material according to the present invention may contain an acrylic oligomer obtained by polymerizing a (meth)acrylic monomer in addition to the curable component related to the radical polymerizable compound. By containing the acrylic oligomer in the active energy ray-curable forming material, curing shrinkage when irradiating and curing the reinforcing film with active energy rays can be reduced, and the interfacial stress between the reinforcing film and the polarizer can be reduced. In order to sufficiently suppress cure shrinkage, the content of the acrylic oligomer is preferably 20 parts by weight or less, and more preferably 15 parts by weight or less, based on 100 parts by weight of the total amount of the curable component. If the content of the acrylic oligomer in the forming material is too large, the reaction rate when the forming material is irradiated with an active energy ray is severely lowered, resulting in poor curing. On the other hand, it is preferable to contain 3 parts by weight or more of the acrylic oligomer, 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 is preferably of low viscosity in consideration of workability and uniformity at the time of coating, it is preferable that the acrylic oligomer obtained by polymerizing a (meth)acrylic monomer is also of low viscosity. As an acrylic oligomer having a low viscosity and capable of preventing cure shrinkage of the reinforcing film, the weight average molecular weight (Mw) is preferably 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 1,000 or more, and particularly preferably 1,500 or more. As the (meth)acrylic monomer constituting the acrylic oligomer, specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 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 (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylic (Meth)acrylic acid such as acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and N-octadecyl (meth)acrylate (Carbon number 1-20) Alkyl esters, and, for example, cycloalkyl (meth) acrylic acid (for example, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.), aralkyl (meth) acrylic (E.g., benzyl (meth) acrylate), polycyclic (meth) acrylate (e.g. 2-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5 -Norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, etc.), hydroxyl group-containing (meth)acrylic acid esters (e.g., hydroxy Ethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)methacrylate, 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, phenoxyethyl (meth)acrylate, etc.), epoxy group-containing (meth)acrylic acid esters (eg glycidyl (meth)acrylate, etc.), halogen-containing (meth)acrylic acid esters (eg For example, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl ( Meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, etc.), alkylamino Alkyl (meth)acrylate (for example, dimethylaminoethyl (meth)acrylate), etc. are 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, "Actflow" manufactured by Soken Chemical, and "JONCRYL" manufactured by BASF Japan.

<Mine generator>

The active energy ray-curable forming material may 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 to the case where the photoacid generator is not contained. The photoacid generator can be represented by the following formula (3):

[Formula 3]

L ⁺ X ^-

(Where, L ⁺ is representative of any of the onium cations addition, X ^-. Is _{^{PF 6 -, SbF 6 -,}} AsF 6 -, SbCl 6 -, BiCl 5 -, SnCl 6 -, ClO 4 -, dithiocarbamate It represents a counter anion selected from the group consisting of ^a) an anion, SCN.

Specific preferred onium salts that make up the photo-acid generator examples include _{^{PF 6 -, SbF 6 -,}} AsF 6 -, SbCl 6 -, BiCl 5 -, SnCl 6 -, ClO 4 -, dithiocarbamate anion, SCN ^- is selected from It is an onium salt composed of an anion.

Specifically, "Syracure UVI-6992", "Syracure UVI-6974" (above, manufactured by Dow Chemical Japan Co., Ltd.), "Adeka Optoma-SP150", "Adeka Optoma-SP152", "Ah Deka Optoma SP170'', ``Adeka Optoma SP172'' (above, manufactured by ADEKA Co., Ltd.), ``IRGACURE250'' (manufactured by Ciba Specialty Chemicals), ``CI-5102'', ``CI-2855'' (above, manufactured by Nippon Soda), `` San-Aid SI-60L", "San-Aid SI-80L", "San-Aid SI-100L", "San-Aid SI-110L", "San-Aid SI-180L" (above, manufactured by Sanshin Chemical), "CPI- 100P", "CPI-100A" (above, manufactured by San Apro Co., Ltd.), "WPI-069", "WPI-113", "WPI-116", "WPI-041", "WPI-044", "WPI- 054", "WPI-055", "WPAG-281", "WPAG-567", and "WPAG-596" (above, manufactured by Wako Pure Chemical Industries, Ltd.) are mentioned as preferred 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, more preferably 0.05 to 5 parts by weight, particularly preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable component. .

The formation of the reinforcing film using the curable forming material is performed by coating a curable forming material on the surface of a polarizer and then curing it.

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 desired thickness. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse or 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 the forming material>

The curable forming material is used as an active energy ray-curable forming material or a thermosetting forming material. The active energy ray-curable forming material can be used in an electron beam-curable type, an ultraviolet-curable type, or a visible ray-curable type.

≪Active energy ray curing type≫

In the active energy ray-curable forming material, a reinforcing film is formed by applying an active energy ray-curable forming material to a polarizer, irradiating an active energy ray (electron beam, ultraviolet ray, visible light, etc.), and curing the active energy ray-curing forming material. The irradiation direction of the active energy ray (electron ray, ultraviolet ray, visible ray, etc.) can be irradiated from any suitable direction. Preferably, it is irradiated from the side of the reinforcing film.

≪Electron beam hardening type≫

In the electron beam curing type, any suitable conditions may be employed as long as the irradiation condition of the electron beam is a condition capable of curing the active energy ray curing type forming material. For example, in electron beam irradiation, the acceleration voltage is preferably 5 kV to 300 kV, more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5kV, there is a risk that the electron beam does not reach the deepest part of the reinforcing film, resulting in insufficient curing. If the acceleration voltage exceeds 300kV, the penetration force passing through the sample is too strong, and there is a risk of damaging the polarizer. . 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 becomes insufficient in curing, and when it exceeds 100 kGy, the polarizer is damaged, resulting in a decrease in mechanical strength or yellowing, so that predetermined optical properties cannot be obtained.

Electron beam irradiation is usually carried out in an inert gas, but if necessary, it may be carried out in the atmosphere or under a condition in which oxygen is slightly introduced.

≪Ultraviolet ray curing type, visible ray curing type≫

As the active energy ray, it is preferable to use an active energy ray containing visible light having a wavelength range of 380 nm to 450 nm, and particularly, an active energy ray having the highest irradiation amount of visible light having a wavelength range of 380 nm to 450 nm. As the active energy ray, a gallium-encapsulated metal halide lamp and an LED light source emitting light in a wavelength range of 380 to 440 nm are preferable. Or 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, excimer laser, or sunlight. The included light source may be used, and a band pass filter may be used to block ultraviolet rays having a wavelength shorter than 380 nm.

≪Heat curing type≫

On the other hand, the thermosetting forming material is applied to a polarizer and then heated to initiate polymerization with a thermal polymerization initiator to form a cured product layer (reinforcing film). The heating temperature is set depending on the thermal polymerization initiator, but is about 60 to 200°C, preferably 80 to 150°C.

In addition, as a 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 such as methyl-α-cyanoacrylate, ethyl-α-cyanoacrylate, butyl-α-cyanoacrylate, and octyl-α-cyanoacrylate. -α-cyanoacrylate, cyclohexyl-α-cyanoacrylate, methoxy-α-cyanoacrylate, and the like. As the cyanoacrylate-based forming material, for example, what is 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 an epoxy resin is used alone, it is cured by adding a photoinitiator and irradiating an active energy ray. In the case of adding an epoxy curing agent as an epoxy-based forming material, for example, one used as an epoxy-based adhesive can be used. The use type of the epoxy-based forming material may be used as a one-component type containing an epoxy resin and a curing agent thereof, but can be used as a two-component type in which a curing agent is mixed with an epoxy resin. The epoxy-based forming material is usually used as a solution. The solution may be a solvent system or an aqueous system such as an emulsion, a colloidal dispersion, or an aqueous solution.

As the epoxy resin, various compounds containing two or more epoxy groups in the molecule can be exemplified. For example, a bisphenol type epoxy resin, an aliphatic type epoxy resin, an aromatic type epoxy resin, a halogenated bisphenol type epoxy resin, and a biphenyl type epoxy resin And the like. Further, the epoxy resin can be appropriately determined according to the epoxy equivalent or the number of functional groups, but from the viewpoint of durability, those having an epoxy equivalent of 500 or less are preferably used.

The curing agent for the epoxy resin is not particularly limited, and various types of phenol resins, acid anhydrides, carboxylic acids, and polyamines can be used. As the phenol resin-based curing agent, for example, a phenol novolac resin, a bisphenol novolac resin, a xylylene phenol resin, a cresol novolac resin, or the like is used. As an acid anhydride type hardening agent; Maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic anhydride, and the like, and examples of the carboxylic acid-based curing agent include carboxylic acids such as pyromellitic acid and trimellitic acid, and block carboxylic acids added with vinyl ether. have. As the epoxy-based two-liquid forming material, for example, one composed of two liquids of an epoxy resin and polythiol, one composed of two liquids of an epoxy resin and polyamide, and the like can be used.

The blending amount of the curing agent varies depending on the equivalent of the epoxy resin, but is preferably 30 to 70 parts by weight, and further 40 to 60 parts by weight based on 100 parts by weight of the epoxy resin.

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

As an isocyanate-type forming material, what is used as a crosslinking agent in formation of an adhesive layer is mentioned. As the isocyanate crosslinking 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-bisisocyanate methylcyclohexane, hexamethylene diisocyanate, tetramethylxylylene diisocyanate, m- Isopropenyl-α,α-dimethylbenzyl isocyanate, methylenebis4-phenyl isocyanate, p-phenylenediisocyanate or dimers thereof or trimers such as tris isocyanuric acid (6-isocyanate hexyl), and further biurets thereof (biuret), a polyhydric alcohol such as trimethylolpropane, and a reaction with a polyvalent amine, etc. are mentioned. Moreover, as an isocyanate-type crosslinking agent, it is preferable to have 3 or more isocyanate groups, such as tris (6-isocyanate hexyl) of isocyanate. As an isocyanate-type forming material, what is used as an isocyanate-type adhesive agent is mentioned, for example.

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

In addition, the isocyanate-based crosslinking agent may be used in which a protecting group is provided to the terminal isocyanate group. Examples of the protecting group include oxime and lactam. What has protected the isocyanate group dissociates the protecting group from the isocyanate group by heating, and the isocyanate group reacts.

In addition, a reaction catalyst may 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 or two or more reaction catalysts can be used. The amount of the reaction catalyst is usually 5 parts by weight or less based on 100 parts by weight of the isocyanate-based crosslinking agent. When the amount of the reaction catalyst is large, the crosslinking reaction speed is accelerated, resulting in foaming of the forming material. Even if a forming material after foaming is used, sufficient adhesiveness cannot be obtained. Usually, in the case of using a reaction catalyst, 0.01 to 5 parts by weight and further 0.05 to 4 parts by weight are preferable.

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

In addition, it does not specifically limit as an amine catalyst. It is preferable to have at least one organic group such as an alicyclic group such as quinuclidine, amidine, and diazabicyclodecene. In addition, triethylamine, etc. are mentioned as an amine catalyst. Further, examples of the reaction catalyst 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 system such as an emulsion, a colloidal dispersion, or an aqueous solution. As the organic solvent, there is no particular limitation as long as the components constituting the forming material are uniformly dissolved. As an organic solvent, toluene, methyl ethyl ketone, ethyl acetate, etc. are mentioned, for example. In addition, even in the case of using an aqueous system, for example, alcohols such as n-butyl alcohol and isopropyl alcohol, and ketones such as acetone may be blended. In the case of water-based, it can be carried out by using a dispersing agent or by introducing a functional group having low reactivity with an isocyanate group such as a carboxylic acid salt, a sulfonic acid salt, or a quaternary ammonium salt, or a water-dispersible component such as polyethylene glycol to the isocyanate-based crosslinking agent.

Formation (curing) of a reinforcing film using a cyanoacrylate-based forming material, an epoxy-based forming material, or an isocyanate-based forming material can be appropriately selected depending on the type of the forming material, but is usually about 30 to 100°C, preferably Is achieved by drying at 50 to 80°C for about 0.5 to 15 minutes. In addition, in the case of the cyanoacrylate-based forming material, since curing is quick, a reinforcing film can be formed in a shorter time than the above time.

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

The polymeric polyol compound has a weight average molecular weight of 100 to 4,000, preferably having two or more hydroxyl groups in one molecule, and polyether polyol, polyester polyol, polycarbonate polyol, and the like are used. As the polymer polyol compound, the weight average molecular weight is preferably 500 to 4,000, further preferably 600 to 3,500, and more preferably 1,000 to 3,000.

Examples of the polyether polyol include aliphatic polyether polyols and aromatic polyether polyols. More specifically, for example, dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, and hexamethylene glycol, trihydric alcohols such as trimethylolpropane, glycerin, pentaerythritol, etc. Polyether obtained by addition polymerization of ethylene oxide, propylene oxide, tetrahydrofuran or the like is used. These may be used alone or in combination of two or more.

Examples of the polyester polyol include aliphatic polyester polyols and aromatic polyester polyols. More specifically, the dihydric alcohol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and other alcohols and dibasic acids such as adipic acid, azelaic acid, and sebacic acid. Polyester made of a polycondensate is used. These may be used alone, or two or more may be mixed and used.

In addition, polybutadiene having hydroxyl groups at both ends of the molecule, butadiene acrylonitrile copolymer, polydiene-based polyols such as polyisoprene, polybutadiene hydrogenated products having hydroxyl groups at both ends of the molecule, poly And polyolefin-based polyols such as isoprene hydrogenated products and polyisobutylene.

Further, examples of the polyamino compound used as the chain extender include aliphatic polyamino compounds and aromatic polyamino compounds. More specifically, for example, ethylenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), diethyltoluenediamine (DETDA), 4,4'-bis-(sec- Butyl) diphenylmethane, 2,4-tolylenediamine, 2,6-tolylenediamine, xylylenediamine, hexanediamine, isophoronediamine, and the like. In particular, ethylenediamine and the like are preferred. These may be used alone, or two or more may be mixed and used.

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

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 even more preferably 1 to 5 parts by weight based on 100 parts by weight of the polymer polyol compound. Durability can be improved by sufficiently raising the molecular weight by using a chain extender.

The isocyanate compound is a polyisocyanate (isocyanate compound) having two or more isocyanate groups, and the same material 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 by the polyester polyol and the isocyanate compound exemplified in advance.

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

Formation (curing) of a reinforcing film using polyurethane may be performed by applying a liquid (coating solution) of polyurethane prepared in advance to a polarizer, or a composition containing the polymer polyol compound and an isocyanate compound. A reinforcing film may be formed of polyurethane as a reactant cured after being applied to a polarizer. The reinforcing film may be formed by drying at about 30 to 100°C, preferably at 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 can be carried out for the purpose of accelerating the reaction, particularly in an isocyanate-based forming material, a polyurethane-based forming material, and the like, when the isocyanate does not sufficiently react even after initial curing (a state in which a reactor remains in the reinforcing film). The annealing treatment can be carried out in either a dry or humidified atmosphere. The annealing treatment temperature is about 30 to 100°C, preferably 50 to 80°C, similar to the conditions at the time of the initial curing. There is no specific limitation on the annealing time.

Further, the weight average molecular weight of the polyurethane is preferably 30,000 to 200,000, more preferably 4 to 150,000, and still more preferably 50,000 to 130,000.

(Measurement of weight average molecular weight)

The weight average molecular weight of the high molecular polyol compound and polyurethane was measured under the following conditions by GPC (gel permeation chromatography).

Analysis device: HLC-8120GPC manufactured by Tosoh Corporation.

Column: Tosoh Corporation make, G7000HXL + GMHXL + GMHXL.

Column size: each 7.8 mm Φ × 30 cm total 90 cm.

Column temperature: 40°C.

Flow rate: 0.8 ml/min.

Injection volume: 100 μl.

Eluent: Tetrahydrofuran.

Detector: differential refractometer.

Standard sample: polystyrene.

In addition, 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 radically polymerizable functional group of a carbon-carbon double bond such as a (meth)acryloyl group and a vinyl group. Compounds can be used. Examples of the compound include 2-isocyanatoethyl acrylate (made by Showa Denko, product name Karenz AOI), 1,1-(bisacryloyloxymethyl) ethyl isocyanate (made by Showa Denko, Ka Lens BEI), and the like. In addition, as the compound, a reaction product of a polymer having a diisocyanate compound as a constituent component and a hydroxyl group-containing (meth)acrylate can be used. Examples of such a reactant include a reaction product of a polymer containing 2-hydroxyethyl acrylate and 1,6-diisocyanatohexane as a constituent component (manufactured by BASF, product name Laroma LR9000).

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

Further, the reinforcing film may be formed from a forming material that does not contain a curable component, or, for example, may be formed from a forming material containing 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".

As said polyvinyl alcohol resin, polyvinyl alcohol is mentioned, for example. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. Further, examples of the polyvinyl alcohol-based resin include saponified products of a copolymer of vinyl acetate and a copolymerizable monomer. When the copolymerizable monomer is ethylene, an ethylene-vinyl alcohol copolymer can be obtained. Further, examples of the copolymerizable monomer include unsaturated carboxylic acids such as (anhydride) maleic acid, fumaric acid, crotonic acid, itaconic acid, and (meth)acrylic acid, and esters thereof; Α-olefins such as ethylene and propylene, (meth)allylsulfonic acid (soda), sulfonic acid soda (monoalkyl maleate), disulfonic acid sodaalkyl maleate, N-methylolacrylamide, acrylamide alkylsulfonic acid alkali salt, N- Vinylpyrrolidone, N-vinylpyrrolidone derivatives, and the like. These polyvinyl alcohol-based resins may be used alone or in combination of two or more. Polyvinyl alcohol obtained by saponifying polyvinyl acetate is preferred from the viewpoint of satisfying moisture and heat resistance and water resistance by controlling the heat of fusion of crystals of the reinforcing film to 30 mj/mg or more.

The saponification degree of the polyvinyl alcohol-based resin may be, for example, 95% or more, but from the viewpoint of satisfying moist heat resistance and water resistance by controlling the heat of fusion of crystals of the reinforcing film to 30 mj/mg or more, the saponification degree is 99.0. % Or more is preferable, and further, 99.7% or more is preferable. The degree of saponification indicates the ratio of units that are actually saponified into vinyl alcohol units among units that can be converted into vinyl alcohol units by saponification, and the residue is a vinyl ester unit. The degree of saponification can be obtained according to JIS K 6726-1994.

The average degree of polymerization of the polyvinyl alcohol-based resin may be, for example, 500 or more, but the average degree of polymerization is 1,000 or more from the viewpoint of satisfying moist heat resistance and water resistance by controlling the heat of crystal melting of the reinforcing film to 30 mj/mg or more. It is preferable, more preferably 1,500 or more, and further preferably 2,000 or more. The average degree of polymerization of the polyvinyl alcohol-based resin is measured according to JIS-K 6726.

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 its copolymer can be used. As said hydrophilic functional group, an acetoacetyl group, a carbonyl group, etc. are mentioned, for example. In addition, a modified polyvinyl alcohol obtained by acetalization, urethanization, etherification, grafting, phosphoric acid esterification, etc. of a polyvinyl alcohol-based resin may be used.

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

As the crosslinking agent, a compound having at least two functional groups having reactivity with polyvinyl alcohol-based resin can be used. Alkylene diamines having an alkylene group and two amino groups, such as ethylenediamine, triethylenediamine, and hexamethylenediamine; Tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane torylene diisocyanate adduct, triphenylmethane triisocyanate, methylenebis(4-phenylmethane triisocyanate, isophorone diisocyanate and ketone oxime blocks or phenol blocks thereof, etc. Isocyanates of; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, digly Epoxys such as cidyaniline and diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, and butylaldehyde; glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleindialdehyde , Dialdehydes such as phthaldialdehyde; amino-formaldehyde resins such as methylolurea, methylolmelamine, alkylated methylolurea, alkylated methylolated melamine, acetoguanamine, condensates of benzoguanamine and formaldehyde; Adipic acid dihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, isophthalic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid di Dicarboxylic acid dihydrazide such as hydrazide and itaconic acid dihydrazide; water-soluble dihydrazine such as ethylene-1,2-dihydrazine, propylene-1,3-dihydrazine, butylene-1,4-dihydrazine Among these, amino-formaldehyde resins and water-soluble dihydrazines are preferred As amino-formaldehyde resins, compounds having a methylol group are preferred, and among them, methylolmelamine, a compound having a methylol group, is particularly preferred. .

The curable component (crosslinking agent) may be used from the viewpoint of improving water resistance, but the ratio thereof is preferably 20 parts by weight or less, 10 parts by weight or less, and 5 parts by weight or less based on 100 parts by weight of the polyvinyl alcohol-based resin.

The forming material is prepared by dissolving the polyvinyl alcohol-based resin in a solvent. Examples of the solvent include water, dimethylsulfoxide, dimethylformamide, dimethylacetamide N-methylpyrrolidone, various glycols, polyhydric alcohols such as alcohols, and amines such as ethylenediamine and diethylenetriamine. I can. 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 (e.g., aqueous solution) is not particularly limited, but in consideration of coating properties and standing stability, 0.1 to 15% by weight, preferably 0.5 to 10% by weight to be.

Further, examples of additives that can be blended into the above forming material (eg, aqueous solution) include plasticizers and surfactants. As a plasticizer, polyhydric alcohols, such as ethylene glycol and glycerin, are mentioned, for example. As a surfactant, a nonionic surfactant is mentioned, for example.

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

<Surface treatment layer>

A surface treatment layer may be provided on one or both surfaces of the flexible polarizing film of the present invention. Examples of the surface treatment layer include a hard coat layer, an anti-glare treatment layer, an antireflection layer, and an anti-sticking layer. It is preferable that it is a hard coat layer as said surface treatment layer. As the material for forming the hard coat layer, for example, a thermoplastic resin, a material cured by heat or radiation can be used. Examples of the material include radiation curable resins such as thermosetting resins, ultraviolet curing resins, and electron beam curing resins. Among these, an ultraviolet-curable resin capable of efficiently forming a cured resin layer by a simple processing operation by curing treatment by ultraviolet irradiation is preferable. Examples of these curable resins include various types of polyester, acrylic, urethane, amide, silicone, epoxy, melamine, and other monomers, oligomers, and polymers.

In addition, as the surface treatment layer, an antiglare treatment layer or an antireflection layer for the purpose of improving visibility can be provided. Further, an anti-glare layer or an anti-reflection layer can be provided on the hard coat layer. The constituent material of the anti-glare 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, or the like is used. Multiple layers may be provided for the antireflection layer. In addition, as a surface treatment layer, a sticking prevention layer etc. are mentioned.

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

<Adhesive layer>

A pressure-sensitive adhesive layer may be provided on one or both sides of the flexible polarizing film of the present invention. For the formation of the pressure-sensitive adhesive layer, an appropriate pressure-sensitive adhesive may be used, and there is no particular limitation on the kind. Examples of the adhesive include rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, vinylalkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives.

Among these pressure-sensitive adhesives, those having excellent optical transparency, appropriate wettability, cohesiveness and adhesive properties, and excellent weather resistance and heat resistance are preferably used. As exhibiting these characteristics, an acrylic pressure-sensitive adhesive is preferably used.

As a method of forming the pressure-sensitive adhesive layer, for example, a method of applying the pressure-sensitive adhesive to a peel-treated separator and drying and removing a polymerization solvent to form a pressure-sensitive adhesive layer, and then transferring the pressure-sensitive adhesive to a flexible polarizing film. It is produced by a method of forming a pressure-sensitive adhesive layer on a polarizer by applying and drying the polymerization solvent or the like. Further, in applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be appropriately added.

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 still more preferably 5 to 35 µm.

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a peel-treated sheet (separator) until it is provided for practical use.

<surface protection film>

In addition, a surface protection film can be provided on the flexible polarizing film of the present invention. The surface protection film usually has a base film and an adhesive layer, and protects a flexible polarizing film through the said adhesive layer.

As the base film of the surface protection film, a film material having isotropic property or close to isotropic property is selected from the viewpoint of inspection property and manageability. Examples of the film material include polyester resins such as polyethylene terephthalate films, cellulose resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, and polyolefin resins. Transparent polymers such as resin and acrylic resin are mentioned. Among these, polyester resins are preferred. The base film may be used as a laminate of one or two or more film materials, or a stretched product of the film may be used. The thickness of the base film is generally 500 µm or less, and preferably 10 to 200 µm.

As the pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer of the surface protection film, a pressure-sensitive adhesive made of a (meth)acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as the base polymer can be appropriately selected and used. have. From the viewpoint of transparency, weather resistance, heat resistance, and the like, an acrylic pressure-sensitive adhesive having 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 adhesion. It is usually about 1 to 100 µm, preferably 5 to 50 µm.

In addition, in the surface protective film, a peeling treatment layer can be provided on the surface opposite to the side on which the pressure-sensitive adhesive layer is provided in the base film using a low-adhesion material such as silicone treatment, long chain alkyl treatment, or fluorine treatment.

<Other optical layers>

The flexible polarizing film of the present invention is a replacement for a polarizer or a polarizing film (a transparent protective film is installed on the polarizer), and it is possible to expand the development of various uses that could not be applied in the conventional polarizer or polarizing film, for example It can also be used as an optical film laminated with other optical layers. The optical layer is not particularly limited, but for example, in the case of using the flexible polarizing film of the present invention as a substitute for the polarizer, a protective film (including a phase difference film, a brightness enhancing film, a diffusion film, etc.) used to protect the polarizer is used. In the case of using as a substitute for a polarizing film, a reflective plate, a transflective plate, a retardation film (including a wavelength plate such as 1/2 or 1/4), a visual compensation film, a liquid crystal display device or an organic EL display device, etc. One or two or more optical layers, which may be used for the formation of an image display device or the like, may be used.

<Intervening layer>

The optical layer and the flexible polarizing film may be laminated through an intervening layer such as an adhesive layer, an adhesive layer, and an undercoat layer (primer layer). At this time, it is preferable to stack both with an intervening layer without an air gap.

The flexible polarizing film of the present invention or an optical film using the same can be suitably used for the formation of various image display devices such as a liquid crystal display device and an organic EL display device. The liquid crystal display device may be formed according to the conventional method. That is, a liquid crystal display device is generally formed by properly assembling a liquid crystal cell, a flexible polarizing film of the present invention or an optical film using the same, and constituent parts such as a lighting system as necessary to embed a driving circuit, but the present invention Except for the use of the flexible polarizing film of, it is not particularly limited, and is similar to the prior art. Also for the liquid crystal cell, any kind of IPS type, VA type, or the like can be used, but it is particularly preferable for the IPS type.

[Example]

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, both parts and% in each example are based on weight. The room temperature standing conditions which are not specifically limited below are all 23 degreeC and 65% RH.

<Production of the polarizer (A0)>

An amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having an absorption rate of 0.75% and a Tg of 75°C was subjected to corona treatment on one side of the substrate, and polyvinyl alcohol (polymerization degree 4,200, saponification) on the corona treated side 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1,200, acetoacetyl modification degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon Kosei Chemical Industry Co., Ltd., brand name ``Kosefimer Z200'') at a ratio of 9:1 An aqueous solution containing as was applied and dried at 25° C. to form a PVA-based resin layer having a thickness of 11 μm, and a laminate was prepared.

The obtained laminate was uniaxially stretched at the free end 2.0 times in the longitudinal direction (length direction) between rolls having different circumferential speeds in an oven at 120°C (air auxiliary stretching treatment).

Next, the laminate was immersed for 30 seconds in an insolubilization bath having a liquid temperature of 30°C (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment).

Subsequently, the polarizing plate was immersed in a dyeing bath having a liquid temperature of 30° C. while adjusting the iodine concentration and immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 parts by weight of iodine was blended with respect to 100 parts by weight of water, and 1.0 part by weight of potassium iodide was blended and immersed in an aqueous solution of iodine for 60 seconds (dyeing treatment).

Next, it was immersed for 30 seconds in a crosslinking bath having a liquid temperature of 30°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid) (crosslinking treatment).

Thereafter, the laminate was immersed in an aqueous solution of boric acid at a liquid temperature of 70°C (an aqueous solution obtained by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide) with respect to 100 parts by weight of water. Uniaxial stretching was performed so that the total stretching ratio was 5.5 times in the direction (longitudinal direction) (underwater stretching treatment)

Thereafter, 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 respect to 100 parts by weight of water) (washing treatment).

By the above, an optical film layered product including a polarizer having a thickness of 5 μm was obtained.

<Production of polarizer (A1-A2)>

In the production of the polarizer A0 described above, the polarizers A1-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 of the polarizers (A0 to A2), optical properties (single transmittance, polarization degree), and boric acid concentration.

[Table 1]

<Preparation of a polarizer (B1) (a 12 μm-thick polarizer)>

A polyvinyl alcohol film having an average polymerization degree of 2,400 and a saponification degree of 99.9 mol% and a thickness of 30 µm was immersed in hot water at 30° C. for 60 seconds to swell. Then, it was immersed in an aqueous solution having a concentration of 0.3% of iodine/potassium iodide (weight ratio = 0.5/8), and the film was dyed while stretching to 3.5 times. Then, it stretched so that the total draw ratio might become 6 times in 65 degreeC boric acid ester aqueous solution. 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 properties of the obtained polarizer (B1) were 42.8% in transmittance and 99.99% in polarization degree.

<Production of a polarizer (B2) (a polarizer having a thickness of 23 μm)>

A 75-micrometer-thick polyvinyl alcohol film with an average degree of polymerization of 2,400 and a saponification degree of 99.9 mol% was immersed in hot water at 30° C. for 60 seconds to swell. Then, the film was dyed while immersing in an aqueous solution having a concentration of 0.3% of iodine/potassium iodide (weight ratio = 0.5/8) and stretching to 3.5 times. Then, it stretched so that the total draw ratio might become 6 times in 65 degreeC boric acid ester aqueous solution. 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 properties of the obtained polarizer (B2) were 42.8% in transmittance and 99.99% in polarization degree.

<Material for forming the reinforcing film>

(1) polyurethane-based material

50 parts of a urethane prepolymer composed of tolylene isocyanate and trimethylolpropane (manufactured by Tosoh Corporation, Coronate L) 50 parts of polycarbonate polyol (manufactured by Sumica Bayer Urethane, Desmo Fan C3100XP) 50 parts, dioctyl tin dilaurate catalyst (Tokyo Fine Chemical Co., Ltd. make, Enviizer OL-1) 0.1 part was added, and a coating liquid adjusted to 35% of solid content concentration was obtained using methyl isobutyl ketone as a solvent.

(2) UV curing material

A reaction product of a polymer consisting of 2-hydroxyethyl acrylate and 1,6-diisocyanatohexane in 50 parts of urethane acrylate oligomer (manufactured by Nippongo Seigaku Co., Ltd., magnetic UV1700TL) (manufactured by BASF, product name) Roma LR9000) 50 parts and 3 parts of a photoinitiator (manufactured by BASF, IRGACURE907) were added, and a coating solution adjusted to a solid content concentration of 35% was obtained using methyl isobutyl ketone as a solvent.

(3) Water-based resin emulsion material

Pure water was added as a solvent to an acrylic emulsion (trade name: SE-2915E manufactured by Taisei Fine Chemical) to obtain a coating solution adjusted to a solid content concentration of 30%.

<Protective film (acrylic) and adhesive>

Corona treatment was applied to the easily-adhesion-treated surface of a (meth)acrylic resin film having a lactone ring structure having a thickness of 20 μm and used.

As an adhesive applied to the above protective film (acrylic), 40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloylmorpholine (ACMO), and a photoinitiator "IRGACURE 819" (manufactured by BASF) 3 By mixing parts by weight, an ultraviolet curable adhesive was prepared.

Example 1 (Manufacture of flexible polarizing film)

The thickness after curing of the polyurethane-based material (1) of the reinforcing film on the polarizer (first side) of the polarizer (A0) obtained above (the optical film laminate including a polarizer having a thickness of 5 μm) was 5 using a wire bar coater. After coating so as to be µm, the first reinforcing film was formed by initial curing under conditions of 60°C and 10 minutes, and then further annealing under conditions of 60°C and 12 hours. Next, after bonding a surface protective film (manufactured by Nitto Denko, RP301) on the first reinforcing film, the amorphous PET substrate of the optical film laminate was peeled off. After that, apply the polyurethane material (1) of the reinforcing film to a polarizer (the second side that is the peeling surface) using a wire bar coater so that the thickness after curing becomes 5 μm, and then initially cured under conditions of 60°C and 10 minutes. Then, the second reinforcing film was formed by further performing an annealing treatment at 60° C. for 12 hours. Thereafter, a flexible polarizing film having a reinforcing film on both surfaces of the polarizer was obtained by removing the surface protection film that has been attached to the first reinforcing film.

Examples 2 to 4

In Example 1, a flexible polarizing film having a reinforcing film on both surfaces of a polarizer was manufactured in the same manner as in Example 1 except that the type of polarizer and the thickness of the reinforcing film were changed as shown in Table 2.

Example 5 (Manufacture of flexible polarizing film)

The thickness after curing of the UV curing material (2) of the reinforcing film on the polarizer (first side) of the polarizer (A0) obtained above (the optical film laminate including a polarizer having a thickness of 5 μm) was cured using a wire bar coater. After coating so as to be 5 μm, it was heated at 60° C. for 1 minute. A first reinforcing film was formed by irradiating the coated film after heating with ultraviolet rays having an accumulated light quantity of 300 mJ/cm ^{2 with a high pressure mercury lamp.} Next, after bonding a surface protective film (manufactured by Nitto Denko, RP301) on the first reinforcing film, the amorphous PET substrate of the optical film laminate was peeled off. Thereafter, the UV curing material (2) of the reinforcing film was coated on a polarizer (the second surface as a peeling surface) to a thickness of 5 μm after curing using a wire bar coater, followed by heating at 60° C. for 1 minute. A second reinforcing film was formed by irradiating the heated coating film with ultraviolet rays having an accumulated light quantity of 300 mJ/cm 2 with a high pressure mercury lamp. Thereafter, a flexible polarizing film having a reinforcing film on both surfaces of the polarizer was obtained by removing the surface protection film that has been attached to the first reinforcing film.

Example 6 (Manufacture of flexible polarizing film)

The thickness after curing of the water-based resin emulsion material 3 of the reinforcing film on the polarizer (first side) of the polarizer (A0) obtained above (the optical film laminate including a polarizer having a thickness of 5 μm) was cured using a wire bar coater. After coating so as to be 5 μm, it was cured under conditions of 80° C. and 5 minutes to form a first reinforcing film. Next, after bonding a surface protective film (manufactured by Nitto Denko, RP301) on the first reinforcing film, the amorphous PET substrate of the optical film laminate was peeled off. After that, apply the water-based resin emulsion material (3) of the reinforcing film to a polarizer (the second side that is the peeling surface) using a wire bar coater so that the thickness after curing becomes 5 μm, and then cured under conditions of 80° C. To form a second reinforcing film. Thereafter, a flexible polarizing film having a reinforcing film on both surfaces of the polarizer was obtained by removing the surface protection film that has been attached to the first reinforcing film.

Example 7

In Example 1, in the same manner as in Example 1, except that the first reinforcing film was not provided, a flexible polarizing film having a second reinforcing film on only one side of the polarizer was manufactured.

Example 8

In Example 1, in the same manner as in Example 1 except that the second reinforcing film was not provided, a flexible polarizing film having the first reinforcing film only on one side of the polarizer was manufactured.

Comparative Examples 1 to 3

In Example 1, a polarizing film having a reinforcing film on both sides of a polarizer was prepared 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 a single protective polarizing film)

The UV-curable adhesive was applied to the polarizer (first side) of the polarizer (A0) obtained above (the optical film laminate including a polarizer having a thickness of 5 μm) so that the thickness of the cured adhesive layer became 1 μm, and the protective film After bonding (acrylic), ultraviolet rays were irradiated as active energy rays to cure the adhesive. Ultraviolet irradiation is performed using a gallium-enclosed metal halide lamp, irradiation device: Light HAMMER10 valve manufactured by Fusion UV Systems, Inc.: V valve, peak illuminance: 1600mW/cm2, accumulated irradiation dose of 1000/mJ/cm2 (wavelength 380 to 440nm). , The irradiance of ultraviolet rays was measured using a Sola-Check system manufactured by Solatell. Subsequently, the amorphous PET substrate of the optical film laminate was peeled off to obtain an unprotected polarizing film.

Samples were prepared with respect to the flexible polarizing film obtained in the above examples, the polarizing film having the reinforcing film obtained in the comparative example, and the piece protective polarizing film, and the following evaluation was performed. The results are shown in Table 2. In addition, in Comparative Examples 5 to 7, the single polarizers A0, A1, and B1 were evaluated. The polarizers (A0, A1) having a thin film thickness were retired, and evaluation in a single body was impossible to measure except for rigidity. Evaluation was carried out at 23° C. and 65% RH.

<Single transmittance (T) and polarization degree (P) of a polarizer>

The single transmittance (T) and polarization degree (P) of the obtained polarizing film were measured using a spectral transmittance meter with an integrating sphere (Dot-3c of Murakami Color Technology Research Institute).

In addition, the degree of polarization (P) is the transmittance (parallel transmittance: Tp) when two identical polarizing films are stacked so that their transmission axes are parallel to each other, and the transmittance (orthogonal transmittance: It can be calculated by applying Tc) to the following equation.

Polarization degree (P)(%)={(Tp-Tc)/(Tp+Tc)} ^1/2 ×100

Each transmittance is expressed as a Y value obtained by correcting the visibility by a 2 degree field of view (C light source) of JIS Z8701 with 100% of the perfect polarization obtained through a Glan Taylor prism.

<Measurement of compressive elastic modulus>

TI900 TriboIndenter (manufactured by Hysitron) was used to measure the compressive modulus. The obtained polarizer (polarizing film) with a reinforcing film was cut into a size of 10 mm×10 mm, fixed to the support of the Tribolndenter device, and the compressive modulus was measured by a nanoindentation method. At this time, the position was adjusted so that the indenter used was press-fit in the vicinity of the center of the transparent layer. Measurement conditions are shown below.

Indenter used: Berkovich (trigonal pyramid)

Measurement method: single indentation measurement

Measurement temperature: 23℃

Indentation depth setting: 100 nm

<Torsion (salt ash) test>

It was carried out using a planar body no-load torsion tester manufactured by Yuasa Systems Co., Ltd. (Product name: main body TCDM111LH and jig: planar body no-load torsion test jig).

After fixing both short sides of a 100mm (absorption axis direction)×150mm (transmission axis direction) rectangular object (1, 矩形物) (sample) with the twisting clips (11, 12) of the tester, one short side is clipped. While fixing with (12), the clip 11 on the short side of the other side was twisted under the following conditions. Fig. 2 shows the twisted state.

Torsion speed: 10rpm

Torsion angle: 45 degrees

Number of twists: 100

The state of the sample after the torsion test was visually evaluated according to the following criteria.

(Circle): Cracks and leakage did not occur. Also, no fold marks remained.

?: Cracks and leakage did not occur. However, fold marks remained.

×: Cracks and leakage occurred. Also, fold marks remained.

<U-shaped extension test>

It was carried out using a U-shaped stretch tester (product name: main body DLDM111LH and jig: planar body no-load U-shaped stretch test jig) manufactured by Yuasa Systems Co., Ltd.

Double-sided tape (not shown) on both ends (x, y) (50 mm) of a rectangular object 1 (sample) of 50 mm (absorption axis direction) x 100 mm (transmission axis direction) to the support portions 21 and 22 of the tester ), the rectangular object 1 was stretched and contracted so that the one side (the first side) of the rectangular object 1 becomes U-shaped inward, and the rectangular object was bent (the first side of the transmission axis direction). Of bending). Fig. 3 shows the state of one process of U-shaped expansion and contraction. In the U-shaped extension, the bend R (bending radius) was set to be 0, and the rectangular object 1 (sample) was folded in two from a flat state and bent until contacted. In the bending, both ends (x, y) are brought into contact with both ends (x, y) by the operation of the support, and at the same time, the other parts of the rectangular object (1) (sample) are separately installed plate portions (23, 24). ) To be inserted from the outside with no load to make contact.

In addition, the bending by the stretching was performed in the same manner as above in which the other side of the rectangular object (the second surface) became a U-shaped inward (bending on the second surface side in the transmission axis direction).

In addition, the bending by stretching is performed in the same manner as above so that the first and second surfaces are U-shaped inward for a rectangular object (sample) of 50 mm (transmission axis direction) × 100 mm (absorption axis direction). (Bending on the first side and the second side in the absorption axis direction).

Stretching speed: 30rpm

Bending (R): 0

Number of expansions: 100

The state of the U-shaped stretching test sample was evaluated by visual observation according to the following criteria.

(Circle): No cracking and leakage of light occurred in any of the bending of the first and second surfaces in the transmission axis direction and the first and second surfaces in the absorption axis direction. Also, no fold marks were left.

×: A crack or leakage occurred in any one of the bending of the first and second surfaces in the transmission axis direction and the first and second surfaces in the absorption axis direction. Or a crease was identified.

Criteria of cracks, fold marks, and leakage in the torsion test and U-shaped stretch test are as follows.

"Crack" indicates that a sample (a flexible polarizing film, a polarizing film having a reinforcing film, or the entire layer constituting a single-protective polarizing film, or a part of the layer) is penetrated, and tearing or cracking has occurred.

"Fold marks" are visible marks that remain after the load is removed due to bending or local load on the sample (a flexible polarizing film, a polarizing film having a reinforcing film, or the entire layer constituting a single-protective polarizing film or a partial layer thereof) Indicates that this has occurred.

"Leakage" indicates that a torn or crack has occurred in the polarizer itself. To confirm the leakage, the sample after the test (a flexible polarizing film, a polarizing film having a reinforcing film, or the entire layer constituting a single-protective polarizing film) and another conventional polarizing film were bonded to both sides of the glass in a cross-Nichol state, and This was done by shining light.

<Bending maintenance test>

A 200 mm (absorption axis direction) x 300 mm (transmission axis direction) rectangular object 1 (sample) was placed on a horizontal stand 31. Subsequently, after folding the rectangular object 1 in three in the transmission axis direction (long axis direction), a load 32 of 100 g was applied so that a load was applied to the front of the top portion, and left for 5 minutes. Fig. 4 shows the bending state. After that, the load 32 was removed.

In addition, the same operation (however, the sample was folded in three in the absorption axis direction (major axis direction)) was performed on a rectangular object (sample) of 200 mm (transmission axis direction) x 300 mm (absorption axis direction).

After the bending maintenance test, it was visually checked whether the sample was kept folded in three, and when the folded shape in three was maintained, the sample was returned to its original state (plane), and the sample was visually evaluated according to the following criteria. The evaluation was performed three times for each of the samples on the long side in the direction of the transmission axis and the long side in the direction of the absorption axis.

(Circle): In any sample, the shape folded into three was maintained, and at the same time, there was no crack and the original state was maintained (retention property).

×: The shape folded into three was not maintained in any one sample. Alternatively, the shape folded into three was maintained, but a crack occurred at the time of load (no retention).

In addition, the judgment of "crack" is the same as the torsion test and U-shaped stretch test.

<Stiffness test>

Yasuda Seiki Manufacturing No. A 476 cantilever type softness tester was used. In addition, in this test, in order to exclude the influence of static electricity, a sample or the like used for the test was appropriately discharged.

A rectangular object 1 (sample) of 50 mm (absorption axis direction) × 150 mm (transmission axis direction) has a flat surface (50 mm × 150 mm: the same size as the sample) and has a 45° inclined surface at one end of the long side. , It was installed to be located in front of the smooth SUS plate 41 having a trapezoidal cross section (see FIG. 5). The sample was installed so that there was an inclined surface in the direction of the transmission axis.

The sample was moved by sliding it quietly toward the inclined surface 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 contacted the inclined surface (2). The government measured the distance (L) (mm) the sample traveled in the plane.

For a rectangular object 1 (a sample of a flexible polarizing film) of 50 mm (transmission axis direction) x 150 mm (absorption axis direction), the same operation (however, the installation of the sample is to have an inclined surface in the absorption axis direction) was performed. .

The stiffness (mm) is 3 for each of the two patterns of the long side in the transmission axis direction and the long side in the absorption axis direction, the first side as the upper side and the second side as the upper side, respectively. Times, the shortest linear distance (L) (mm) was measured (a total of 12 samples), and it was set as the arithmetic average value of them.

In addition, in one or more measurements of any one of the 12 samples, when there was a sample that could not be measured due to deformation or curl of the sample, the sample was judged as impossible to measure.

<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) x 150 mm (transmission axis direction) with a multipurpose test piece cutting machine (dumbell).

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 performed by fixing the sides of both sides in the transmission axis direction with clamps 51 and 52 (the distance 53 between the initial clamps was 50 mm), and pulling the side of the clamp 52 on one side (see FIG. 6 ). ). The point at which the sample started breaking or plastic deformation was evaluated as "tensile strength".

The tensile strength was taken as the arithmetic mean value of the result of measuring three times.

[Table 2]

1 flexible polarizing film
a transparent protective film
b1 first reinforcing membrane
b2 second reinforcing film

Claims (17)

A polyvinyl alcohol-based polarizer having a thickness of 10 μm or less formed by adsorbing orienting a polyvinyl alcohol-based resin in one direction and iodine or a dichroic dye on the polyvinyl alcohol-based resin. There are no cracks, creases, and leakage of light after performing the following twist (salt ash) test in which the polyvinyl alcohol-based resin is twisted in the orientation direction,
Having a reinforcing film in close contact with the polyvinyl alcohol polarizer on at least one side of the polyvinyl alcohol polarizer,
The flexible polarizing film, characterized in that the thickness of the reinforcing film is 15㎛ or less.
<Torsion test>
It was carried out using a planar body no-load torsion tester manufactured by Yuasa Systems Co., Ltd. (Product name: main body TCDM111LH and jig: planar body no-load torsion test jig).
After fixing both short sides of a 100mm (absorption axis direction) x 150mm (transmission axis direction) rectangular object (flexible polarizing film) with the twisting clip of the tester, one short side is fixed with a clip and the other short side The clip on the side was twisted under the following conditions.
Torsion speed: 10rpm
Torsion angle: 45 degrees
Number of twists: 100 The method of claim 1,
After the following U-shaped stretching test in which the polyvinyl alcohol-based resin is oriented and stretched in a U-shape in a direction orthogonal to the orientation direction, cracks, creases, and leakage in any direction Flexible polarizing film, characterized in that there is no.
<U-shaped extension test>
It was carried out using a U-shaped stretch tester (product name: main body DLDM111LH and jig: planar body no-load U-shaped stretch test jig) manufactured by Yuasa Systems Co., Ltd.
After fixing both ends (50 mm) of a rectangular object (flexible polarizing film) of 50 mm (absorption axis direction) x 100 mm (transmission axis direction) to the support of the tester with double-sided tape, one side of the rectangular object (first side) Stretching so as to form a U-shaped inward was performed under the following conditions, and the rectangular object was bent (bending on the first surface side in the direction of the transmission axis). In the U-shape extension, the bending (R) (bending radius) was set to be 0, and the rectangular object (flexible polarizing film) was folded in two from a flat state and bent until contacted. In the bending, both ends are brought into contact with both ends by the operation of the support unit, and at the same time, the other part of the rectangular object (flexible polarizing film) is inserted into contact with no load from both outer sides by a separately installed plate part.
In addition, the bending by the stretching was performed in the same manner as the above in which the other side of the rectangular object (the second surface) became a U-shaped inward (bending on the second surface side in the transmission axis direction).
In addition, the bending due to the stretching is the same as above so that the first side and the second side are U-shaped inward for a rectangular object (flexible polarizing film) of 50 mm (transmission axis direction) × 100 mm (absorption axis direction). (Bending on the first side and the second side in the absorption axis direction).
Stretching speed: 30rpm
Bending (R): 0
Number of expansions: 100 The method of claim 1,
After performing the following bending maintenance test in which the polyvinyl alcohol-based resin is bent and held in an orientation direction in which the polyvinyl alcohol-based resin is oriented and a direction orthogonal to the orientation direction, the bending shape is maintained in either direction and no cracking occurs. Flexible polarizing film, characterized in that.
<Bending maintenance test>
A 200 mm (absorption axis direction) x 300 mm (transmission axis direction) rectangular object (flexible polarizing film) was placed on a horizontal stand. Subsequently, after folding the rectangular object into three pieces in the transmission axis direction (long axis direction), a load of 100 g was applied so that a load was applied to the front of the uppermost portion, and left for 5 minutes. After that, the load was removed.
In addition, the same operation (however, the sample was folded in three in the absorption axis direction (long axis direction)) was performed on a rectangular object (flexible polarizing film) of 200 mm (transmission axis direction) x 300 mm (absorption axis direction).
After the bending maintenance test, it was visually checked whether or not the sample remained folded in three, and when the folded shape in three was maintained, the sample was returned to its original state (plane) and evaluated visually. The evaluation was performed three times for each of the samples on the long side in the direction of the transmission axis and the long side in the direction of the absorption axis. The method of claim 1,
In the following stiffness test in an orientation direction in which the polyvinyl alcohol-based resin is oriented and a direction orthogonal to the orientation direction, a stiffness degree (mm) is 60 mm or less.
<Stiffness test>
Yasuda Seiki Manufacturing No. A 476 cantilever type softness tester was used. In addition, in this test, in order to exclude the influence of static electricity, a flexible polarizing film used for the test was appropriately discharged and performed.
A rectangular object (flexible polarizing film) of 50 mm (absorption axis direction) × 150 mm (transmission axis direction) has a flat top (50 mm × 150 mm: the same size as the flexible polarizing film) and has a 45° inclined surface at one end of the long side. It was installed to be located in front of this trapezoidal smooth SUS plate. Installation of the flexible polarizing film was performed to have an inclined surface in the direction of the transmission axis.
The flexible polarizing film was moved by sliding it quietly toward the inclined surface at an extrusion speed of 10 mm/sec. The movement of the flexible polarizing film was stopped at a location where the tip of the flexible polarizing film first contacted the inclined surface. The government measured the distance (L) (mm) the sample traveled in the plane. For a rectangular object (flexible polarizing film) of 50 mm (transmission axis direction) x 150 mm (absorption axis direction), the same operation (however, in the case of installing the flexible polarizing film, an inclined surface was performed in the absorption axis direction).
The stiffness (mm) is 3 times and the shortest for each of the two patterns of the long side in the transmission axis direction and the long side in the absorption axis direction, with the first side as the upper side and the second side as the upper side, respectively. The linear distance (L) (mm) was measured (a total of 12 samples), and it was set as the arithmetic mean value. In addition, in one or more measurements of any one of the 12 samples, when there was a sample that could not be measured due to deformation or curl of the sample, the sample was judged as impossible to measure. The method of claim 1,
In the following tensile test, a flexible polarizing film having a tensile strength of 5 N/10 mm or more in a direction orthogonal to the orientation direction in which the polyvinyl alcohol-based resin is oriented.
<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) x 150 mm (transmission axis direction) with a multipurpose test piece cutting machine (dumbell).
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 carried out while fixing both sides in the transmission axis direction with a clamp (the distance between the initial clamps was 50 mm), and pulling one of the clamp sides. The point at which the sample started breaking or plastic deformation was evaluated as "tensile strength".
The tensile strength was taken as the arithmetic mean value of the result of measuring three times. The method of claim 1,
The polyvinyl alcohol-based polarizer has optical properties represented by a single transmittance (T) and a polarization degree (P), by the following formula:
P>-(10 ^0.929T-42.4 -1)×100 (however, T<42.3), or
A flexible polarizing film configured to satisfy a condition of P≥99.9 (however, T≥42.3). delete delete The method of claim 1,
A flexible polarizing film comprising: a first reinforcing film having a thickness of 15 μm or less on a first side of the polyvinyl alcohol-based polarizer, and a second reinforcing film having a thickness of 15 μm or less on the other second side of the polyvinyl alcohol polarizer. The method of claim 9,
A flexible polarizing film, characterized in that a difference in thickness between the first and second reinforcing films is 10 μm or less. The method of claim 1,
The flexible polarizing film, characterized in that the ratio of the thickness of the reinforcing film to the thickness of the polyvinyl alcohol-based polarizer is 0.4 or more. The method of claim 1,
The reinforcing film is a flexible polarizing film, characterized in that the compressive elastic modulus at 23 °C is 1 MPa or more. The method of claim 1,
The reinforcing layer is a flexible polarizing layer, wherein the reinforcing layer is not substantially oriented. The method of claim 1,
The flexible polarizing film, characterized in that the reinforcing film is a resin film. The method of claim 14,
The resin film is a flexible polarizing film, characterized in that the formed product of a thermosetting resin or an active energy ray-curable resin. As the manufacturing method of the 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 obtained by adsorbing orienting a polyvinyl alcohol-based resin in one direction and iodine or a dichroic dye on the polyvinyl alcohol-based resin,
Including a step (2) of forming a reinforcing film by coating a liquid material containing a resin component or a curable component capable of constituting a resin film on at least one side of the polyvinyl alcohol-based polarizer, and then solidifying or curing the liquid material. A method of manufacturing a flexible polarizing film, characterized in that. An image display device comprising the flexible polarizing film according to any one of claims 1 to 6 and 9 to 15.

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