JP6808372B2 - Optical film, its manufacturing method and display device - Google Patents

Description

The present invention relates to an optical film, a manufacturing method thereof, and a display device.

Currently mainly used flat plate display devices are divided into light emitting display devices that emit light by themselves and light receiving type display devices that require a separate light source, and as a method for improving the image quality of these, compensation films and the like are used. Optical films are often used.

In the case of a light emitting display device, for example, an organic light emitting diode display, the visibility and contrast ratio may decrease due to the reflection of external light by a metal such as an electrode. The liquid crystal display device (liquid crystal display, LCD) of the light receiving type display device may reflect external light and have a sunglasses effect depending on the type such as a transmissive type, a transflective type, and a reflective type.

In this regard, the use of optical films is being considered.

However, the currently developed optical film is thick, which hinders the thinning of the display device. In addition, the thickness and optical durability of the optical film make it difficult to apply to flexible display devices.

One embodiment provides an optical film that can achieve a thin thickness and is applicable to flexible display devices.

Another embodiment provides a method for producing the optical film.

Yet another embodiment provides a display device that includes the optical film.

According to one embodiment, a polarizing film containing a polyolefin and a dichroic dye, a first photoalignment film located on one surface of the polarizing film, and a first liquid crystal layer located on one surface of the first photoalignment film. The polarizing film, the first photoalignment film, and the first liquid crystal layer provide an optical film having an integrated structure in close contact with each other.

The first photo-alignment film is preferably coated from a photo-alignment film solution containing a photoreactive compound and a solvent, and the reaction product of the photoreactive compound is directed in a predetermined direction with respect to the surface of the polarizing film. The solubility parameters of the polyolefin and the solvent are oriented so that the solubility parameters of the following relational expressions 1 to 3 can be satisfied.

[Relationship formula 1]
_{0.9 ≦ │H D (P) -H} D (S) │ ≦ 1.7
[Relational expression 2]
_{1.9 ≦ │H P (P) -H} P (S) │ ≦ 4.1
[Relational expression 3]
4.9 ≤ │ _{H H} (P) -H _H (S) │ ≤ 10.8
In the relational expressions 1 to 3,
H _D (P) is the Hansen solubility parameter for dispersion force of the polyolefin (Hansen solubility parameter),
H D _(S) is the Hansen solubility parameter for dispersion force of said solvent,
H P _(P) is the Hansen solubility parameter for polarity of the polyolefin,
H P _(S) is the Hansen solubility parameter for polarity of the solvent,
H H _(P) is the Hansen solubility parameter for hydrogen bonding of the polyolefin,
H H _(S) is a Hansen solubility parameter for hydrogen bonding of the solvent.

The polyolefin may contain polypropylene, and the solvent contains any one of propylene glycol monomethyl ether, a mixed solvent of propylene glycol monomethyl ether and toluene, and a mixed solvent of propylene glycol monomethyl ether and cyclohexanone. be able to.

It is not necessary to include an adhesive or an adhesive between the polarizing film and the first photoalignment film, and between the first photoalignment film and the first liquid crystal layer.

The first liquid crystal layer may be a phase delay layer.

The optical film may be a flexible film having a radius of curvature of 1 mm to 10 mm.

The optical film can have a thickness of about 50 μm or less.

The optical film may further include an auxiliary layer located on another surface of the polarizing film or one surface of the first liquid crystal layer.

The auxiliary layer can include a vertically oriented liquid crystal.

The optical film further includes a second photoalignment film located on one surface of the first liquid crystal layer and a second liquid crystal layer located on one surface of the second photoalignment film, and the polarizing film and the first light. The alignment film, the first liquid crystal layer, the second photoalignment film, and the second liquid crystal layer can have an integrated structure in close contact with each other.

The second photoalignment film is preferably coated from a solution for a photoalignment film containing a photoreactive compound and a solvent, and the reaction product of the photoreactive compound is predetermined with respect to the surface of the first liquid crystal layer. It should be oriented in the direction.

The first liquid crystal layer and the second liquid crystal layer may be phase delay layers, respectively, and the first liquid crystal layer and the second liquid crystal layer may have different phase delays from each other.

Any one of the first liquid crystal layer and the second liquid crystal layer may have an in-plane phase difference with respect to a wavelength of 550 nm of about 230 nm to 300 nm, and the first liquid crystal layer and the second liquid crystal layer. The other one may have an in-plane phase difference of about 110 nm to 160 nm with respect to a wavelength of 550 nm.

The optical film may further include an auxiliary layer located on another surface of the polarizing film or one surface of the second liquid crystal layer.

The auxiliary layer can include a vertically oriented liquid crystal.

According to another embodiment, a display device including the optical film is provided.

According to still another embodiment, a step of preparing a polarizing film by melting and mixing polyolefin and a dichroic dye, and coating one surface of the polarizing film with a solution for a photoalignment film containing a photoreactive compound and a solvent. The polyolefin includes a step, a step of drying the coated solution for a photoalignment film to form a first photoalignment film, and a step of forming a first liquid crystal layer on one surface of the first photoalignment film. And the solubility parameters of the solvent provide a method for producing an optical film that satisfies the solubility parameters of the following relational expressions 1 to 3.

[Relationship formula 1]
_{0.9 ≦ │H D (P) -H} D (S) │ ≦ 1.7
[Relational expression 2]
_{1.9 ≦ │H P (P) -H} P (S) │ ≦ 4.1
[Relational expression 3]
4.9 ≤ │ _{H H} (P) -H _H (S) │ ≤ 10.8
In the relational expressions 1 to 3,
H _D (P) is the Hansen solubility parameter for dispersion force of the polyolefin (Hansen solubility parameter),
H D _(S) is the Hansen solubility parameter for dispersion force of said solvent,
H P _(P) is the Hansen solubility parameter for polarity of the polyolefin,
H P _(S) is the Hansen solubility parameter for polarity of the solvent,
H H _(P) is the Hansen solubility parameter for hydrogen bonding of the polyolefin,
H H _(S) is a Hansen solubility parameter for hydrogen bonding of the solvent.

The step of drying the coated solution for a photoalignment film can be performed at about 25 to 100 ° C.

The photoreactive compound can include a photodimerized compound.

The polyolefin may contain polypropylene, and the solvent contains any one of propylene glycol monomethyl ether, a mixed solvent of propylene glycol monomethyl ether and toluene, and a mixed solvent of propylene glycol monomethyl ether and cyclohexanone. be able to.

The manufacturing method can further include a step of forming a second photoalignment film on one surface of the first liquid crystal layer and a step of forming a second liquid crystal layer on one surface of the second photoalignment film.

The manufacturing method can further include a step of forming an auxiliary layer on another surface of the polarizing film or one surface of the first liquid crystal layer.

By providing an optical film having strong durability and a thin thickness, a thin display device having good display quality can be realized. In addition, the folded or bent portion has strong durability and can be applied to a flexible display device.

It is the schematic sectional drawing of the optical film which concerns on one Embodiment. It is a schematic cross-sectional view which shows the polarizing film used in the optical film of FIG. It is the schematic which shows the external light reflection prevention principle of an optical film. It is the schematic sectional drawing of the optical film which concerns on another embodiment. It is a schematic cross-sectional view of the optical film which concerns on still another embodiment. It is a schematic cross-sectional view of the optical film which concerns on still another embodiment. It is sectional drawing which shows schematically the organic light emission display device which concerns on one Embodiment. It is sectional drawing which shows schematically the liquid crystal display device which concerns on one Embodiment.

Hereinafter, embodiments will be described in detail so that those having ordinary knowledge in the technical field can easily carry out the embodiments. However, embodiments are feasible in a variety of different embodiments and are not limited to the embodiments described herein.

In the drawings, the thickness is enlarged to clearly represent the various layers and regions. The same drawing reference numerals are given to similar parts throughout the specification. When a part such as a layer, a film, an area, or a plate is "above" another part, this is not only when it is "directly above" the other part, but there is another part in the middle. Including the case. Conversely, when one part is "directly above" another part, it means that there is no other part in the middle.

Hereinafter, the optical film according to the embodiment will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of an optical film according to an embodiment, and FIG. 2 is a schematic cross-sectional view showing a polarizing film used in the optical film of FIG.

Referring to FIG. 1, the optical film 100 according to one embodiment includes a polarizing film 110, a first photoalignment film 120, and a first liquid crystal layer 130.

Referring to FIG. 2, the polarizing film 110 may be an integrally stretched film made of a melt blend of a polyolefin 71 and a dichroic dye 72.

The polyolefin 71 may be, for example, polyethylene (PE), polypropylene (PP), a copolymer of polyethylene and polypropylene (PE-PP), or a mixture thereof.

Polypropylene (PP) can have, for example, a melt flow index (MFI) of about 0.1 g / 10 min to about 5 g / 10 min. Here, the melt flow index (MFI) indicates the amount of the polymer in the melted state flowing per 10 minutes, and is related to the viscosity of the polyolefin in the melted state. That is, it can be seen that the smaller the melt flow index (MFI), the higher the viscosity of the polyolefin, and the larger the melt flow index (MFI), the lower the viscosity of the polyolefin. When the melt flow index (MFI) of the polypropylene is within the above range, the workability can be effectively improved and the physical characteristics of the final product can be effectively improved. Specifically, polypropylene can have a melt flow index (MFI) of about 0.5 g / 10 min to about 5 g / 10 min.

The polyethylene-polypropylene copolymer (PE-PP) can contain about 1% by weight to about 50% by weight of ethylene groups based on the total content of the copolymer. When the content of ethylene groups in the polyethylene-polypropylene copolymer (PE-PP) is within the above range, the phase separation between polypropylene and the polyethylene-polypropylene copolymer (PE-PP) is effectively prevented or mitigated. Can be done. In addition, while having excellent light transmittance and orientation, the stretching ratio at the time of stretching can be increased, and improved polarization characteristics can be realized. Specifically, the polyethylene-polypropylene copolymer (PE-PP) can contain about 1% by weight to about 25% by weight of ethylene groups with respect to the total content of the copolymer.

The polyethylene-polypropylene copolymer (PE-PP) can have a melt flow index (MFI) of about 5 g / 10 min to about 15 g / 10 min. When the melt flow index (MFI) of the polyethylene-polypropylene copolymer (PE-PP) is within the above range, the processability can be effectively improved and the physical properties of the final product can be effectively improved. .. Specifically, the polyethylene-polypropylene copolymer (PE-PP) can have a melt flow index (MFI) of about 10 g / 10 min to about 15 g / 10 min.

The polyolefin 71 can have a haze of about 5% or less. When the polyolefin 71 has a haze in the above range, the transmittance is increased and excellent optical properties can be obtained. Specifically, the polyolefin 71 can have a haze of about 2% or less, and more specifically, a haze of about 0.5% to about 2%.

The polyolefin 71 can have a crystallinity of about 50% or less. When the polyolefin 71 has the crystallinity in the above range, the haze can be lowered and excellent optical characteristics can be achieved. Specifically, the polyolefin 71 can have a crystallinity of about 30% to about 50%.

The polyolefin 71 may have a transmittance of about 85% or more in the wavelength region of about 400 to 780 nm. The polyolefin 71 is uniaxially stretched. The uniaxial direction can be the same as the length direction of the dichroic dye 72 described later.

The dichroic dye 72 is dispersed in the polyolefin 71 and is arranged in one direction along the stretching direction of the polyolefin 71. The dichroic dye 72 can transmit only one polarization orthogonal component of the two polarization orthogonal components with respect to a predetermined wavelength region.

The dichroic dye 72 may be contained in an amount of about 0.01 to 5 parts by weight based on 100 parts by weight of the polyolefin 71. By being included in the above range, when the polarizing film is formed, it is possible to exhibit sufficient polarizing characteristics without lowering the transmittance. Within the above range, about 0.05 to 1 part by weight may be contained with respect to 100 parts by weight of the polyolefin 71.

The polarizing film 110 may have a dichroic ratio of about 2 to 14 at the maximum absorption wavelength (λ _max ) in the visible light region. It may be about 3 to 10 within the above range. Here, the two-color ratio is a value obtained by dividing the plane polarization absorption in the direction perpendicular to the axis (axis) of the polymer by the polarization absorption in the horizontal direction, and is obtained by the following mathematical formula 1.

[Formula 1]
DR = Log (1 / T _⊥ ) / Log (1 / T _‖ )
In the above formula 1,
DR is the two-color ratio of the polarizing film,
T _‖ is the light transmittance of the polarizing film with respect to the light incident parallel to the transmission axis of the polarizing film.
T _⊥ is the light transmittance of the polarizing film with respect to the light incident perpendicular to the transmission axis of the polarizing film.

The dichroic ratio can indicate the degree to which the dichroic dyes 72 are arranged side by side in one direction in the polarizing film 110, and by having the dichroic ratio in the above range in the visible light wavelength region, the polyolefin The orientation of the dichroic dye 72 can be induced according to the orientation of the chain, and the polarization characteristics can be improved.

The polarizing film 110 can have a polarization efficiency of about 80% or more, and can have a polarization efficiency of about 83 to 99.9% within the above range. Here, the polarization efficiency is obtained by the following mathematical formula 2.

[Formula 2]
PE (%) = [(T _‖ −T _⊥ ) / (T _‖ + T _⊥ )] ^1/2 × 100

In the above formula 2,
PE is polarization efficiency,
T _‖ is the transmittance of the polarizing film with respect to the light incident parallel to the transmission axis of the polarizing film.
T _⊥ is the transmittance of the polarizing film with respect to the light incident perpendicular to the transmission axis of the polarizing film.

The polarizing film 110 can have a relatively thin thickness of about 50 μm or less, and can have, for example, a thickness of about 10 μm to about 50 μm. By having a thickness in the above range, the thickness can be significantly reduced as compared with a polyvinyl alcohol polarizing plate that requires a protective layer such as triacetyl cellulose (TAC), thereby making a thin display device. It can be realized.

The first photoalignment film 120 is a thin film that can be oriented in a predetermined direction by light irradiation, and can contain, for example, a reaction product obtained by cross-linking, polymerization, and / or dimerization of a photoreactive compound. The photoreactive compound can have, for example, at least one photoreactive functional group and at least one crosslinked functional group. For example, the photoreactive compound may be a photodimerized compound.

The photoreactive functional group is, for example, a cinnamate-based functional group represented by the following chemical formula D, a chalcone-based functional group represented by the following chemical formula E, or a coumarin represented by the following chemical formula F. ) System functional group may be used, but the present invention is not limited to this.

In the chemical formulas D to F,
R ₁ is a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C3 alkyl group, a substituted or unsubstituted C1 to C3 alkoxy group or a cyano group.
R ₂ may be a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, or a substituted or unsubstituted cyclohexyl group.

The first photo-alignment film 120 imparts a pretilt angle to the liquid crystal of the first liquid crystal layer 130, which will be described later, so that the first photo-alignment film 120 can be oriented in a predetermined direction. For example, the reaction product of the photoreactive compound of the first photoalignment film 120 may be oriented in a predetermined direction with respect to the surface of the polarizing film 110, and is oriented in the orientation direction of the reaction product of the photoreactive compound. The liquid crystal of the first liquid crystal layer 130 can be oriented accordingly. Here, the predetermined direction may be more than 0 degrees with respect to the surface of the polarizing film 110, or may be, for example, more than 0 degrees and less than 180 degrees. For example, when irradiating polarized ultraviolet rays to impart orientation, the predetermined direction may be a direction substantially parallel to or substantially perpendicular to the direction of the irradiated polarization.

The first photoalignment film 120 may be formed by coating directly above the polarizing film 110, whereby the polarizing film 110 and the first photoalignment film 120 can adhere to each other without the intervention of an adhesive or an adhesive.

The first photoalignment film 120 can be formed, for example, by coating one surface of the polarizing film 110 with a solution for a photoalignment film containing a photoreactive compound and a solvent and drying.

The solvent may be selected from those capable of dissolving the photoreactive compound, for example, toluene, cyclohexanone, cyclopentanone, n-butyl acetate, or Examples thereof include propylene glycol methyl ether (propyrene glycol methyl ether), and two or more mixed solvents selected from these may be used. In addition, any solvent that can be effectively dissolved and applied onto the substrate can be used depending on the type of each component.

At this time, the coating property of the first photoalignment film 120 can be determined according to the degree of interaction between the polarizing film 110 and the solution for the photoalignment film, and specifically, it is included in the polarizing film 110. It can be determined according to the degree of interaction between the polyolefin 71 and the solvent contained in the photoalignment film solution.

The interaction between the polyolefin 71 and the solvent contained in the solution for the photoalignment film is represented by the solubility parameter (solubility parameter). The solubility parameter is a numerical value indicating the degree of interaction between compounds. The smaller the difference in solubility parameter between compounds, the larger the interaction, and the larger the difference in solubility parameter between compounds, the smaller the interaction. Means.

The solubility parameter is represented by, for example, the Hansen solubility parameter. The Hansen solubility parameter can indicate the degree of interaction in consideration of dispersion force, polarity and hydrogen bonding between compounds.

As an example, the solvent contained in the polyolefin 71 and the solution for the photoalignment film can satisfy the solubility parameters of the following relational expressions 1 to 3.

[Relationship formula 1]
_{0.9 ≦ │H D (P) -H} D (S) │ ≦ 1.7
[Relational expression 2]
_{1.9 ≦ │H P (P) -H} P (S) │ ≦ 4.1
[Relational expression 3]
4.9 ≤ │ _{H H} (P) -H _H (S) │ ≤ 10.8
In the relational expressions 1 to 3,
H D _(P) is the Hansen solubility parameter for dispersion force of the polyolefin,
H D _(S) is the Hansen solubility parameter for distributed power of the solvent,
H P _(P) is the Hansen solubility parameter for polarity polyolefin,
H P _(S) is the Hansen solubility parameter for the polar solvent,
H H _(P) is the Hansen solubility parameter for hydrogen bonding polyolefins,
H H _(S) is a Hansen solubility parameter for hydrogen bonding solvents.

By satisfying the solubility parameters of the above relational expressions 1 to 3, the solution for the first photoalignment film can be satisfactorily coated on the polarizing film 110 without dewetting, whereby the polarizing film 110 and the first The photoalignment film 120 can be brought into close contact with each other.

As an example, the polyolefin may contain polypropylene, and the solvent may be any one of propylene glycol monomethyl ether, a mixed solvent of propylene glycol monomethyl ether and toluene, and a mixed solvent of propylene glycol monomethyl ether and cyclohexanone. Can include, but is not limited to.

The first photoalignment film 120 can have a thickness of about 500 nm or less, and within the above range, for example, about 5 nm to 300 nm, and within the above range, about 10 nm to 200 nm. Can have.

The first liquid crystal layer 130 can include at least one type of liquid crystal.

The liquid crystal may be in the shape of a rigid-rod extending in one direction or in the shape of a flat disc, or may be, for example, a monomer, an oligomer and / or a polymer. The liquid crystal can have, for example, a positive or negative birefringence value. The liquid crystal can be oriented in one direction along the optical axis.

The liquid crystal may be a reactive mesogenic liquid crystal, and may have, for example, one or more reactive cross-linking groups. The reactive mesogen liquid crystal is, for example, a rod-shaped aromatic derivative having one or more reactive cross-linking groups, propylene glycol 1-methyl, propylene glycol 2-acetate, and P1-A1- (Z1-A2) n-P2. Compounds represented by (where, at least one of P1 and P2 is an acrylate, a methyllate, a vinyl, a vinyloxy, an epoxy, or a combination thereof. A1 and A2 may contain 1,4-phenylene, 1,4-phenylene, -2,6-diyl group, or a combination thereof, respectively, and Z1 Can include a single bond, -COO-, -OCO-, or a combination thereof, where n can be 0, 1 or 2), although It is not limited to this.

As an example, the first liquid crystal layer 130 may be a phase delay layer.

Phase delay, plane retardation _{(in-plane retardation, R e} ) can be represented by in-plane retardation _{(R e) is} represented by _{R e = (n x -n y} ) d. Here, n _x is the refractive index in the direction in which the in-plane refractive index of the first liquid crystal layer 130 is the largest (hereinafter, referred to as “slow axis”), and n _y is the refractive index of the first liquid crystal layer 130. It is the refractive index in the direction in which the in-plane refractive index is the smallest (hereinafter, referred to as “fast axis”), and d is the thickness of the first liquid crystal layer 130.

The refractive index and / or thickness of the first liquid crystal layer 130 at the slow axis and / or the advance axis can be changed so as to have an in-plane phase difference within a predetermined range. According to an example, 550 nm wavelength (hereinafter, referred to as "reference wavelength") plane retardation of the first liquid crystal layer 130 with respect to _{(R e)} may be about 110Nm～160nm, for example, lambda / 4 plate It may be. In this case, the first liquid crystal layer 130 can circularly polarize the light that has passed through the polarizing film 110 to generate a phase difference, and can affect the reflection and / or absorption of the light.

On the other hand, the phase difference includes an in-plane phase difference ( _Re ) and a thickness direction phase difference (R _th ). The thickness direction phase difference (R _th ) is the phase difference generated in the thickness direction of the first liquid crystal layer 130, and the thickness direction phase difference (R _th ) of the first liquid crystal layer 130 is R _th = {[(((). It is represented by n _x + n _y ) / 2] -n _z } d. Here, n _x is the refractive index on the slow axis of the first liquid crystal layer 130, n _y is the refractive index on the advance axis of the first liquid crystal layer 130, and n _z is perpendicular to n _x and n _y . Refractive index in any direction. As an example, the thickness direction retardation of the first liquid crystal layer 130 with respect to the reference wavelength _{(R th)} may be about -250Nm～250nm.

The first liquid crystal layer 130 may be an anisotropic liquid crystal layer and may have a positive or negative birefringence value.

The first liquid crystal layer 130 can have, for example, a refractive index that satisfies any one of the following relational expressions 4 to 6.

[Relational expression 4]
n _x > n _y = n _z
[Relational expression 5]
n _x < _ny = n _z
[Relational formula 6]
n _x > n _z > n _y
In the equation 4 to 6, _{n x} is the refractive index in the slow axis of the first liquid crystal layer 130, _{n y} is the refractive index at Susumujiku of the first liquid crystal layer 130, _{n z} is _{n x} it is the refractive index in the direction perpendicular to and n _y.

As an example, the first liquid crystal layer 130 may be a protective layer of the polarizing film 110.

The first liquid crystal layer 130 protects the surface of the polarizing film 110 and prevents the dichroic dye 72 contained in the polarizing film 110 from moving to another layer, for example, in a high temperature and high humidity environment. can do. This makes it possible to prevent the optical properties of the optical film from deteriorating in a high temperature and high humidity environment.

The first liquid crystal layer 130 may be coated on the first photoalignment film 120.

The first liquid crystal layer 130 can have a thickness of about 10 μm or less. It can have a thickness of about 1 μm to 10 μm within the range and can have a thickness of about 1 μm to 5 μm within the range.

The optical film 100 may be provided on one side or both sides of the display device, and in particular, is arranged on the screen portion side of the display device and reflects light flowing in from the outside (hereinafter, referred to as “external light”). Can be prevented. Therefore, it is possible to prevent a decrease in visibility due to external light reflection.

FIG. 3 is a schematic view showing the principle of preventing external light reflection of the optical film.

Referring to FIG. 3, the incident unpolarized light passes through the polarizing film 110, and only one of the two polarized orthogonal components, that is, the first polarized orthogonal component, is present. The transmitted and polarized light can change to circularly polarized light while passing through the first liquid crystal layer 130. The circularly polarized light changes its circularly polarized direction while being reflected by the display panel 50 including the substrate, electrodes, etc., and the circularly polarized light passes through the first liquid crystal layer 130 again, and the two polarized lights are orthogonal to each other. Only one other polarization orthogonal component of the components, that is, the second polarization orthogonal component, can pass through. Since the second polarized light orthogonal component cannot pass through the polarizing film 110 and light is not emitted to the outside, it can have an effect of preventing external light reflection.

As described above, the polarizing film 110, the first photoalignment film 120, and the first liquid crystal layer 130 are in close contact with each other by a coating, whereby they have an integrated structure without a separate adhesive or adhesive. Can be done. Thereby, the thickness of the optical film 100 can be reduced, and the optical film 100 can have a thickness of, for example, about 50 μm or less, and within the above range, for example, a thickness of about 35 μm or less. be able to. For example, the optical film 100 can have a thickness of about 10-35 μm.

By having such a thin thickness, it can be effectively applied to a flexible display device such as a foldable display device or a bendable display device. For example, the optical film 100 may be a flexible film having a radius of curvature of about 10 mm or less. Here, the fact that the optical film 100 has flexibility with a radius of curvature of about 10 mm or less means that the optical film 100 is folded and fixed so as to have a radius of curvature of about 10 mm or less, and is left at room temperature for 240 hours for static bending. It means that there is virtually no change in the unfolded and folded part after the test. For example, the optical film 100 has a radius of curvature of about 9 mm or less, about 8 mm or less, about 7 mm or less, about 6 mm or less, about 5 mm or less, about 4 mm or less, about 3 mm or less, about 2 mm or less, or about 1 mm or less. be able to. For example, the optical film 100 has a radius of curvature of about 1 nm to 10 mm, about 1 nm to 9 mm, about 1 nm to 8 mm, about 1 nm to 7 mm, about 1 nm to 6 mm, about 1 nm to 5 mm, about 1 nm to 4 mm, about 1 nm to 3 mm, and about. It can have a flexibility of 1 nm to 2 mm. Hereinafter, optical films according to other embodiments will be described.

FIG. 4 is a schematic cross-sectional view of the optical film according to another embodiment.

Referring to FIG. 4, the optical film 200 according to the present embodiment includes a polarizing film 110, a first photoalignment film 120, and a first liquid crystal layer 130, as in the above-described embodiment.

However, unlike the above-described embodiment, the optical film 200 according to the present embodiment further includes an auxiliary layer 140. In the drawings, for convenience of explanation, it is shown that the auxiliary layer 140 is located on one surface of the polarizing film 110, but the present invention is not limited to this, and the auxiliary layer 140 is located on one surface of the first liquid crystal layer 130. You may be.

As an example, the auxiliary layer 140 can enhance the compensation function in combination with the first liquid crystal layer 130 used as the phase delay layer. The auxiliary layer 140 can include, for example, an isotropic liquid crystal layer. The auxiliary layer 140 can include, for example, a vertically oriented liquid crystal.

For example, the auxiliary layer 140 can have a refractive index that satisfies the following relational expression 7.

[Relational expression 7]
n _z > n _x = n _y

In the relational expression 7, n _x is the refractive index on the slow axis of the auxiliary layer 140, n _y is the refractive index on the advance axis of the auxiliary layer 140, and n _z is perpendicular to n _x and n _y. Refractive index in the direction.

For example, the in-plane phase difference of the auxiliary layer 140 may be 0 nm ≤ R ₀ ≤ 1 nm, and within the above range, for example, 0 nm ≤ R ₀ ≤ 0.5 nm, which is substantially 0. There may be.

As an example, the auxiliary layer 140 may be a protective layer. The auxiliary layer 140 can protect the surface of the polarizing film 110 and prevent, for example, the dichroic dye 72 contained in the polarizing film 110 from moving to another layer in a high temperature and high humidity environment.

The auxiliary layer 140 may be coated on the polarizing film 110 or the first liquid crystal layer 130.

Hereinafter, the optical film according to still another embodiment will be described.

FIG. 5 is a schematic cross-sectional view of the optical film according to still another embodiment.

Referring to FIG. 5, the optical film 300 according to the present embodiment includes a polarizing film 110, a first photoalignment film 120, and a first liquid crystal layer 130, as in the above-described embodiment.

However, unlike the above-described embodiment, the optical film 300 according to the present embodiment further includes a second photoalignment film 150 and a second liquid crystal layer 160.

The second photo-alignment film 150 is a thin film that can be oriented in a predetermined direction by light irradiation, and can contain, for example, a reaction product obtained by cross-linking, polymerization, and / or dimerization of a photo-reactive compound. The photoreactive compound can have, for example, at least one photoreactive functional group and at least one crosslinked functional group. For example, the photoreactive compound may be a photodimerized compound.

The photoreactive functional group may be, for example, a synnamate-based functional group represented by the following chemical formula D, a chalcone-based functional group represented by the following chemical formula E, or a coumarin-based functional group represented by the following chemical formula F. Good, but not limited to this.

In the chemical formulas D to F,
R ₁ is a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C3 alkyl group, a substituted or unsubstituted C1 to C3 alkoxy group or a cyano group.
R ₂ may be a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, or a substituted or unsubstituted cyclohexyl group.

The second photoalignment film 150 imparts a pretilt angle to the liquid crystal of the second liquid crystal layer 160, which will be described later, so that it can be oriented in a predetermined direction.

The second photoalignment film 150 can be formed by coating directly above the first liquid crystal layer 130, whereby the first liquid crystal layer 130 and the second photoalignment film 150 can be formed without the intervention of an adhesive or an adhesive. Can be in close contact with each other.

The second photoalignment film 150 can be formed, for example, by coating one surface of the first liquid crystal layer 130 with a solution for a photoalignment film containing a photoreactive compound and a solvent and drying it.

The solvent may be selected from those capable of dissolving the photoreactive compound, for example, toluene, cyclohexanone, cyclopentanone, n-butyl acetate, or Examples thereof include propylene glycol methyl ether (propyrene glycol methyl ether), and two or more mixed solvents selected from these may be used. In addition, any solvent that can be effectively dissolved and applied onto the substrate can be used depending on the type of each component.

The second photoalignment film 150 imparts a pretilt angle to the liquid crystal of the second liquid crystal layer 160, which will be described later, so that it can be oriented in a predetermined direction. For example, the reaction product of the photoreactive compound of the second photoorientation film 150 is preferably oriented in a predetermined direction with respect to the surface of the first liquid crystal layer 130, and the orientation of the reaction product of the photoreactive compound. The liquid crystal of the second liquid crystal layer 160 can be oriented according to the direction. Here, the predetermined direction may be more than 0 degrees with respect to the surface of the first liquid crystal layer 130, or may be more than 0 degrees to less than 180 degrees, for example. For example, when irradiating polarized ultraviolet rays to impart orientation, the predetermined direction may be a direction substantially parallel to or substantially perpendicular to the direction of the irradiated polarization.

The second photoalignment film 150 can have a thickness of about 500 nm or less, and within the above range, for example, about 5 nm to 300 nm, and within the above range, about 10 nm to 200 nm. Can have.

The second liquid crystal layer 160 can include at least one type of liquid crystal.

The liquid crystal may be in the shape of a steel rod or a flat disc extending in one direction, or may be, for example, a monomer, an oligomer, and / or a polymer. The liquid crystal can have, for example, a positive or negative birefringence value. The liquid crystal can be oriented in one direction along the optical axis.

The liquid crystal may be a reactive mesogen liquid crystal, and may have, for example, one or more reactive cross-linking groups. The reactive mesogen liquid crystal is, for example, a rod-shaped aromatic derivative having one or more reactive cross-linking groups, propylene glycol 1-methyl, propylene glycol 2-acetate, and P1-A1- (Z1-A2) n-P2. Compounds represented by (where, at least one of P1 and P2 is an acrylate, a methyllate, a vinyl, a vinyloxy, an epoxy, or a combination thereof. A1 and A2 may contain 1,4-phenylene, 1,4-phenylene, -2,6-diyl group, or a combination thereof, respectively, and Z1 Can include a single bond, -COO-, -OCO-, or a combination thereof, where n can be 0, 1 or 2), although It is not limited to this.

As an example, the second liquid crystal layer 160 may be a phase delay layer.

As an example, the first liquid crystal layer 130 and the second liquid crystal layer 160 may be phase delay layers, respectively.

As an example, the first liquid crystal layer 130 and the second liquid crystal layer 160 can have different phase delays from each other. For example, any one of the first liquid crystal layer 130 and the second liquid crystal layer 160 may have an in-plane phase difference of about 230 nm to 300 nm with respect to a wavelength of 550 nm, and the first liquid crystal layer 130 and the second liquid crystal The other one of the layers 160 may have an in-plane phase difference of about 110 nm to 160 nm with respect to a wavelength of 550 nm. For example, any one of the first liquid crystal layer 130 and the second liquid crystal layer 160 may be a λ / 2 phase delay layer, and the other of the first liquid crystal layer 130 and the second liquid crystal layer 160. One may be a λ / 4 phase delay layer.

The first liquid crystal layer 130 and the second liquid crystal layer 160 may be anisotropic liquid crystal layers, respectively, and can independently have positive or negative birefringence values.

The first liquid crystal layer 130 and the second liquid crystal layer 160 can independently have a refractive index that satisfies, for example, any one of the following relational expressions 4 to 6.

[Relational expression 4]
n _x > n _y = n _z
[Relational expression 5]
n _x < _ny = n _z
[Relational formula 6]
n _x > n _z > n _y

In the equation 4 to 6, _{n x} is the refractive index in the slow axis of the first liquid crystal layer 130 and the second liquid crystal layer 160, _{n y} is the first liquid crystal layer 130 and the second liquid crystal layer 160 Susumujiku N _z is the refractive index in the direction perpendicular to n _x and n _y .

The second liquid crystal layer 160 may be coated on the second photoalignment film 150.

The second liquid crystal layer 160 can have a thickness of about 10 μm or less. It can have a thickness of about 1 μm to 10 μm within the above range.

In the optical film 300 according to the present embodiment, the polarizing film 110, the first photoalignment film 120, the first liquid crystal layer 130, the second photoalignment film 150, and the second liquid crystal layer 160 are in close contact with each other by coating. Allows you to have an integral structure without a separate adhesive or adhesive.

Hereinafter, the optical film according to still another embodiment will be described.

FIG. 6 is a schematic cross-sectional view of the optical film according to still another embodiment.

Referring to FIG. 6, the optical film 400 according to the present embodiment has the same as the above-described embodiment, that is, the polarizing film 110, the first photoalignment film 120, the first liquid crystal layer 130, and the second photoalignment film. Includes 150 and a second liquid crystal layer 160.

However, the optical film 400 according to the present embodiment further includes an auxiliary layer 140, unlike the above-described embodiment. In the drawings, for convenience of explanation, it is shown that the auxiliary layer 140 is located on one surface of the polarizing film 110, but the present invention is not limited to this, and the auxiliary layer 140 is located on one surface of the second liquid crystal layer 160. You may be.

As an example, the auxiliary layer 140 can enhance the compensation function in combination with the first liquid crystal layer 130 and the second liquid crystal layer 160 used as the phase delay layer. The auxiliary layer 140 can include, for example, an isotropic liquid crystal layer. The auxiliary layer 140 can include, for example, a vertically oriented liquid crystal.

For example, the auxiliary layer 140 can have a refractive index that satisfies the following relational expression 7.

[Relational expression 7]
n _z > n _x = n _y

In the relational expression 7, n _x is the refractive index on the slow axis of the auxiliary layer 140, n _y is the refractive index on the advance axis of the auxiliary layer 140, and n _z is perpendicular to n _x and n _y. Refractive index in the direction.

For example, the in-plane phase difference of the auxiliary layer 140 may be 0 nm ≤ R ₀ ≤ 1 nm, and within the above range, for example, 0 nm ≤ R ₀ ≤ 0.5 nm, which is substantially 0. There may be.

As an example, the auxiliary layer 140 may be a protective layer. The auxiliary layer 140 protects the surface of the polarizing film 110 and prevents the dichroic dye 72 contained in the polarizing film 110 from moving to another layer in an environment such as high temperature and high humidity. Can be done.

The auxiliary layer 140 may be coated on the polarizing film 110 or the second liquid crystal layer 160.

Hereinafter, a manufacturing method according to an embodiment of the above-mentioned optical film will be described.

The method for producing an optical film according to an embodiment includes a step of preparing a polarizing film 110, a step of forming a first photoalignment film 120, and a step of forming a first liquid crystal layer 130.

The steps of preparing the polarizing film 110 include a step of melt-mixing a composition containing a polyolefin 71 and a dichroic dye 72, a step of putting the melt mixture in a mold and pressurizing it to produce a sheet, and a step of producing the sheet. It can include a step of uniaxial stretching.

The polyolefin 71 and the dichroic dye 72 may each be contained in a solid form such as powder, or melt-mixed at a temperature equal to or higher than the melting point (Tm) of the polyolefin 71, stretched, and stretched. It can be manufactured on the polarizing film 110.

In the melt-mixing step, the composition can be melt-mixed at, for example, about 300 ° C. or lower, specifically about 130 to 300 ° C. The step of producing the sheet can be formed by putting the molten mixture in the mold and pressurizing it with a high-pressure press, or by discharging it to a chill roll through a T-die. The uniaxial stretching step can be performed at a temperature of about 25 to 200 ° C. and a stretching rate of about 400% to about 1000%. Here, the stretching ratio refers to the ratio of the length of the sheet before stretching to the length after stretching, and means the degree to which the sheet is stretched after uniaxial stretching.

The steps of forming the first photoalignment film 120 are a step of preparing a solution containing a photoreactive compound and a solvent, a step of applying the solution to one surface of the polarizing film 110, a step of drying, and a step of irradiating light. And include.

The photoreactive compound can have, for example, at least one photoreactive functional group and at least one crosslinked functional group. For example, the photoreactive compound may be a photodimerized compound. For example, the photoreactive compound may be a photodimerized compound having a cinnamoyl group.

As described above, the solvent may be selected from the solvents that can be coated in close contact with one surface of the polarizing film 110, or as an example, among the solvents that satisfy the solubility parameters of the above-mentioned relational expressions 1 to 3. May be selected from.

As an example, the polyolefin may contain polypropylene, and the solvent may be any one of propylene glycol monomethyl ether, a mixed solvent of propylene glycol monomethyl ether and toluene, and a mixed solvent of propylene glycol monomethyl ether and cyclohexanone. Can include, but is not limited to.

The step of applying the solution to one surface of the polarizing film 110 may be, for example, spin coating, slit coating, dip coating, inkjet coating, or the like, but is not limited thereto.

The drying step may be performed at about 100 ° C. or lower, or may be performed, for example, at about 25 to 100 ° C.

The light irradiation may be, for example, ultraviolet irradiation, or may be, for example, polarized ultraviolet irradiation, but is not limited thereto. For example, when the first photoalignment film 120 is irradiated with polarized ultraviolet rays to impart orientation, the reaction product of the photoreactive compound is in a direction substantially parallel to or substantially parallel to the direction of the irradiated polarization. Can be oriented in the vertical direction. The step of forming the first liquid crystal layer 130 may include a step of applying a liquid crystal solution containing a liquid crystal and a solvent on the first photoalignment film 120, a step of drying the liquid crystal solution, and a step of curing. it can.

The step of applying the liquid crystal solution may be, for example, spin coating, slit coating, dip coating, inkjet coating, or the like, but is not limited thereto.

The step of drying the liquid crystal solution may be carried out at about 100 ° C. or lower, or may be carried out, for example, at about 25 to 100 ° C.

The curing step may be photocuring and / or thermosetting, and may be, for example, UV irradiation, but is not limited thereto.

According to the above-described embodiment, the step of forming the auxiliary layer 140 can be further included.

The auxiliary layer 140 can include a step of applying a liquid crystal solution containing a liquid crystal and a solvent on the polarizing film 110 or the first liquid crystal layer 130, a step of drying the liquid crystal solution, and a step of curing.

The step of applying the liquid crystal solution may be, for example, spin coating, slit coating, dip coating, inkjet coating, or the like, but is not limited thereto.

The step of drying the liquid crystal solution may be carried out at about 100 ° C. or lower, or may be carried out, for example, at about 25 to 100 ° C.

The curing step may be photocuring and / or thermosetting, and may be, for example, UV irradiation, but is not limited thereto.

According to the above-described embodiment, the step of forming the second photoalignment film 150 and the second liquid crystal layer 160 can be further included. The steps of forming the second photoalignment film 150 and the second liquid crystal layer 160 can be the same as the steps of forming the first photoalignment film 120 and the first liquid crystal layer 130.

According to the above-described embodiment, the steps of forming the second photoalignment film 150, the second liquid crystal layer 160, and the auxiliary layer 140 can be further included.

The optical films 100, 200, 300, 400 can be applied to various display devices. In particular, as described above, the optical films 100, 200, 300, 400 have a thin thickness and are effective for flexible display devices such as foldable display devices or bendable display devices. Applicable.

The display device according to one embodiment includes a display panel and an optical film located on one surface of the display panel. The display panel may be a liquid crystal display panel or an organic light emitting display panel, but is not limited thereto.

Hereinafter, an organic light emitting display device will be described as an example of the display device.

FIG. 7 is a cross-sectional view schematically showing an organic light emitting display device according to an embodiment.

Referring to FIG. 7, the organic light emitting display device according to the embodiment includes an organic light emitting panel 400 and an optical film 100 located on one surface of the organic light emitting panel 400.

The organic light emitting panel 400 can include a base substrate 410, a lower electrode 420, an organic light emitting layer 430, an upper electrode 440, and a sealing substrate 450.

The base substrate 410 may be made of glass or plastic.

One of the lower electrode 420 and the upper electrode 440 may be an anode and the other one may be a cathode. The anode is an electrode into which holes are injected and is made of a transparent conductive material that has a high work function and allows the emitted light to go out, for example, ITO or IZO. May be good. The cathode is an electrode into which electrons are injected and is made of a conductive material that has a low work function and does not affect organic substances, for example from aluminum (Al), calcium (Ca), and barium (Ba). It may be selected.

The organic light emitting layer 430 contains an organic substance capable of emitting light when a voltage is applied to the lower electrode 420 and the upper electrode 440.

Ancillary layers (not shown) can be further included between the lower electrode 420 and the organic light emitting layer 430, and between the upper electrode 440 and the organic light emitting layer 430. Ancillary layers include a hole transporting layer for balancing electrons and holes, a hole injecting layer, an electron injecting layer, and an electron transporting layer. Layer) can be included.

The encapsulating substrate 450 may be made of glass, metal, or polymer, and may encapsulate the lower electrode 420, the organic light emitting layer 430, and the upper electrode 440 to allow moisture and / or oxygen to flow in from the outside. Can be prevented.

The optical film 100 may be arranged on the side where light is emitted. For example, in the case of a back emission (bottom mechanism) structure in which light is emitted to the base substrate 410 side, it may be arranged outside the base substrate 410, and in the case of a front emission (top emission) structure in which light is emitted to the sealing substrate 450 side. , It may be arranged outside the sealing substrate 450.

As described above, the optical film 100 has an integrated structure in which the polarizing film 110, the first photoalignment film 120, and the first liquid crystal layer 130 are in close contact with each other by coating, and the light passing through the polarizing film 110 is an organic light emitting panel. It is possible to prevent the light from being reflected by a metal such as the electrode of 400 and coming out of the display device, and to prevent the visibility from being lowered by the light flowing in from the outside. Therefore, the display characteristics of the organic light emitting display device can be improved.

Here, the optical film 100 is shown for convenience of explanation, but the above-mentioned optical films 200, 300, and 400 can also be applied in the same manner.

Hereinafter, a liquid crystal display device will be described as an example of the display device.

FIG. 8 is a cross-sectional view schematically showing a liquid crystal display device according to an embodiment.

Referring to FIG. 8, the liquid crystal display device according to the embodiment includes a liquid crystal display panel 500 and an optical film 100 located on one or both sides of the liquid crystal display panel 500.

The liquid crystal display panel 500 has a twisted nematic (TN) mode, a vertically oriented vertical alignment (PVA) mode, a plane alignment switching (inspane switching, IPS) mode, an OCB (optically compensated mode, etc.) and a bend. May be good.

The liquid crystal display panel 500 includes a first display board 510, a second display board 520, and a liquid crystal layer 530 interposed between the first display board 510 and the second display board 520.

The first display plate 510 may include, for example, a thin film transistor (not shown) formed on a substrate (not shown) and a first electric field generating electrode (not shown) connected to the thin film transistor (not shown). The second display plate 520 can include, for example, a color filter (not shown) formed on a substrate (not shown) and a second electric field generating electrode (not shown). However, the present invention is not limited to this, and the color filter may be included in the first display board 510, and the first electric field generation electrode and the second electric field generation electrode may be located together in the first display board 510.

The liquid crystal layer 530 can contain a plurality of liquid crystal molecules. Liquid crystal molecules can have positive or negative permittivity anisotropy. When the liquid crystal molecule has a positive dielectric anisotropy, its long axis is oriented so as to be substantially parallel to the surfaces of the first display plate 510 and the second display plate 520 in the absence of an electric field, and the electric field is generated. In the applied state, the major axis may be oriented so as to be substantially perpendicular to the surfaces of the first display plate 510 and the second display plate 520. On the contrary, when the liquid crystal molecule has a negative dielectric anisotropy, its long axis is oriented substantially perpendicular to the surfaces of the first display plate 510 and the second display plate 520 in the absence of an electric field. The major axis of the electric field may be oriented substantially parallel to the surfaces of the first display plate 510 and the second display plate 520 in a state where an electric field is applied.

The optical film 100 is located outside the liquid crystal display panel 500 and is shown in the drawings as being formed on the lower part and the upper part of the liquid crystal display panel 500, respectively, but is not limited to this, and the lower part and the upper part of the liquid crystal display panel 500 It may be formed in only one of them.

As described above, the optical film 100 has an integrated structure in which the polarizing film 110, the first photoalignment film 120, and the first liquid crystal layer 130 are in close contact with each other by coating, and is as described above.

Here, the optical film 100 is shown for convenience of explanation, but the above-mentioned optical films 200, 300, and 400 can also be applied in the same manner.

Hereinafter, the above-described embodiments of the present invention will be described in more detail through Examples. However, the examples below are for illustration purposes only and do not limit the scope of the invention.

[Manufacturing of polarizing film]
[Manufacturing Example 1]
A polarizing film in which 0.5, 0.2 and 0.3 parts by weight of dichroic dyes represented by the following chemical formulas A, B and C are mixed with 100 parts by weight of polypropylene (HU300, Samsung Total), respectively. Prepare the composition for use.

The composition for a polarizing film is melt-mixed at about 250 ° C. using a DSM Micro-compounder. The melt mixture is placed in a sheet-shaped mold and then pressed with a high-temperature and high-pressure press to produce a film. Next, the film is uniaxially stretched at 115 ° C. at a magnification of 1000% (using a tensile tester manufactured by Instron) to produce a polarizing film having a thickness of 20 um.

The solubility parameters, contact angles and surface energies of the polarizing film are shown in Table 1.

[Comparative Manufacturing Example 1]
A polyvinyl alcohol (PVA) film (PS60, Kuraray) is stretched to 30 μm to prepare a stretched PVA film. Next, a TAC film (manufactured by FUJIFILM) having a thickness of 40 μm is attached to both sides of the stretched PVA film to manufacture a polarizing plate.

[Preparation of composition for photoalignment film]
[Production Examples 2 to 9 and Comparative Production Examples 2 and 3]
A composition for a photo-alignment film is prepared by mixing 3% by weight of a photo-aligned polymer (Nissan Chemical Industries, LTD.) Containing a cinnamoyl group and 97% by weight of a solvent.

Table 2 shows the solubility parameters of the solvents used in Production Examples 2 to 9 and Comparative Production Examples 2 and 3.

[Manufacturing of optical film]
[Example 1]
The composition for a photoalignment film according to Production Example 2 is applied by bar coating on one surface of the polarizing film according to Production Example 1 and dried at 70 ° C. Next, UV irradiation is performed for 5 seconds with a light amount of 30 mW / cm ² to form a photoalignment film. Next, liquid crystal A (UCL-017, DIC Corporation) is applied onto the photoalignment film and dried at 70 ° C. to form a liquid crystal layer to produce an optical film.

[Example 2]
An optical film is produced in the same manner as in Example 1 except that liquid crystal B (RMS03-013C, Merck & Co., Inc.) is used instead of liquid crystal A.

[Example 3]
An optical film is produced in the same manner as in Example 1 except that the composition for a photoalignment film according to Production Example 3 is used instead of the composition for a photoalignment film according to Production Example 2.

[Example 4]
It was carried out except that the composition for the photoaligning film according to Production Example 3 was used instead of the composition for the photoaligning film according to Production Example 2 and the liquid crystal B (RMS03-013C, Merck) was used instead of the liquid crystal A. An optical film is produced in the same manner as in Example 1.

[Example 5]
An optical film is produced in the same manner as in Example 1 except that the composition for a photoalignment film according to Production Example 4 is used instead of the composition for a photoalignment film according to Production Example 2 and dried at 100 ° C.

[Example 6]
The composition for a photoalignment film according to Production Example 2 is applied by bar coating on one surface of the polarizing film according to Production Example 1 and dried at 70 ° C. Next, UV irradiation is performed for 5 seconds with a light amount of 30 mW / cm ² to form a lower photoalignment film. Next, liquid crystal A (UCL-017, DIC Corporation) is applied onto the lower photoalignment film and dried at 70 ° C. to form a lower liquid crystal layer. Next, an upper photoalignment film is applied onto the lower liquid crystal layer in the same manner as the lower photoalignment film, a liquid crystal solution (UCL-017, DIC Corporation) is applied, and the film is dried at 70 ° C. to form an upper liquid crystal layer. Then, the optical film is manufactured.

[Example 7]
Optical in the same manner as in Example 1 except that liquid crystal C (UCL-018, DIC Corporation) was applied to the other surface of the polarizing film according to Production Example 1 and dried at 70 ° C. to further form an auxiliary layer. Manufacture film.

[Example 8]
Optical in the same manner as in Example 6 except that liquid crystal C (UCL-018, DIC Corporation) was applied to the other surface of the polarizing film according to Production Example 1 and dried at 70 ° C. to further form an auxiliary layer. Manufacture film.

[Comparative Example 1]
An optical film is produced by bonding the polarizing plate according to Comparative Production Example 1 and the polycarbonate λ / 4 phase delay layer (WRS, Teijin) using an adhesive (PS-47, Soken).

[Comparative Example 2]
An optical film is produced in the same manner as in Example 1 except that the composition for a photoalignment film according to Comparative Production Example 2 is used instead of the composition for a photoalignment film according to Production Example 2 and dried at 100 ° C. ..

[Comparative Example 3]
An optical film is produced in the same manner as in Example 1 except that the composition for a photoalignment film according to Comparative Production Example 3 is used instead of the composition for a photoalignment film according to Production Example 2 and dried at 110 ° C. ..

[Evaluation]
[Evaluation 1]
Table 3 shows the difference in the solubility parameter between the polarizing film obtained in Production Example 1 and the solvent used in Production Examples 2 to 9 and Comparative Production Examples 2 and 3.

[Evaluation 2: Thickness]
The thicknesses of the optical films according to Examples 1 to 8 and Comparative Example 1 are compared.

The results are shown in Table 4.

With reference to Table 4, it can be confirmed that the optical films according to Examples 1 to 8 have a thickness of about 50 μm or less, and have a large and thin thickness as compared with the optical films according to Comparative Example 1. ..

[Evaluation 3: Coating property]
In the optical films according to Examples 1 to 8 and Comparative Examples 2 and 3, the degree of coating property of the (lower) photo-alignment film and the degree of orientation of the photo-alignment film on the polarizing film is evaluated.

The coating property is evaluated by a polarizing microscope (Olympus, USA), and the orientation is evaluated by KOBRA-WPR (Oji Scientific Instruments, Japan).

The results are shown in Table 5.

With reference to Table 5, it can be confirmed that the optical films according to Examples 1 to 8 have good coating properties and orientation.

[Evaluation 4: Flexibility]
The flexibility of the optical film according to Examples 1 to 8 and Comparative Example 1 is evaluated.

The bending test is performed by a static bending test, and the optical films according to Examples 1 to 8 and Comparative Example 1 are folded and fixed between two stainless steel plates so as to have a radius of curvature (r) of 1 mm, and at room temperature. After leaving it for 240 hours, it is evaluated from the presence or absence of cracks and wrinkles in the unfolded and folded portion.

The results are shown in Table 6.

Referring to Table 6, the optical films according to Examples 1 to 8 can be effectively applied to foldable and / or bendable display devices without any appearance deformation in the state of being folded to a radius of curvature (r) of 1 mm. You can confirm that there is. On the other hand, it can be confirmed that the optical film according to Comparative Example 1 has a large amount of wrinkles and / or cracks.

[Evaluation 5: Stability of optical characteristics]
The stability of the optical properties of the optical film according to Example 1 is evaluated.

The stability of the optical characteristics of the optical film confirms that the liquid crystal layer plays a role as a protective layer of the polarizing film, and the stability of the optical characteristics is compared with the degree of change in the optical characteristics of the polarizing film at high temperature. Compare sex. A reference example is a polarizing film according to Production Example 1 in which a liquid crystal layer is not formed.

The stability of the optical characteristics is evaluated from the presence or absence of change by measuring the light transmittance and the degree of polarization, leaving the optical film at 85 ° C. for 500 hours, and then measuring the light transmittance and the degree of polarization again. ..

Light transmittance is evaluated using a V-7100 UV / Vis spectrophotometer manufactured by JASCO Corporation.

Polarizing efficiency (PE) is determined using the measured light transmittance.

The degree of polarization is calculated by the following mathematical formula 1.

[Formula 1]
PE (%) = [(T _‖ −T _⊥ ) / (T _‖ + T _⊥ )] ^1/2 × 100

In the above formula 1,
PE is the degree of polarization,
T _‖ is the light transmittance of the polarizing film with respect to the light incident parallel to the transmission axis of the polarizing film.
T _⊥ is the light transmittance of the polarizing film with respect to the light incident perpendicular to the transmission axis of the polarizing film.

The results are shown in Tables 7 to 10.

With reference to Tables 7 to 10, the optical film according to Example 1 has a reduced light transmittance and polarization degree after being left at a high temperature for a long time as compared with a polarizing film having no liquid crystal layer (reference example). It can be seen that the degree is large and low. This is because the liquid crystal layer of the optical film is used as a protective layer of the polarizing film, and it is possible to prevent the dichroic dye of the polarizing film from moving to the outside, which improves the stability of the optical properties of the optical film. Expected to have been done.

Although preferable examples of the present invention have been described above, the present invention is not limited to this, and the present invention is variously modified and implemented within the scope of claims, the detailed description of the invention, and the scope of the attached drawings. It is possible, and it goes without saying that this also belongs to the scope of the present invention.

100, 200, 300, 400 Optical film 110 Polarizing film 120 First light alignment film 130 First liquid crystal layer 140 Auxiliary layer 150 Second light alignment film 160 Second liquid crystal layer 50 Display panel 400 Organic light emitting display panel 410 Base substrate 420 Lower part Electrode 430 Organic light emitting layer 440 Upper electrode 450 Encapsulation substrate 500 Liquid crystal display panel 510 First display board 520 Second display board 530 Liquid crystal layer

Claims (20)

A polarizing film containing polyolefin and a dichroic dye,
The first photoalignment film located on one surface of the polarizing film and
Including a first liquid crystal layer located on one surface of the first photoalignment film,
The polarizing film, the first photo-alignment film, and the first liquid crystal layer, have a unitary structure in close contact with each other,
An optical film that does not contain an adhesive and an adhesive between the polarizing film and the first photoalignment film, and between the first photoalignment film and the first liquid crystal layer . The polyolefin optical film according polypropylene including, in claim 1. The optical film according to claim 1, wherein the first liquid crystal layer is a phase delay layer. The optical film according to claim 1, which is a flexible film having a radius of curvature of 1 mm to 10 mm. The optical film according to claim 1, which has a thickness of 50 μm or less. The optical film according to claim 1, which has a thickness of 10 μm to 35 μm. The optical film according to claim 1, further comprising an auxiliary layer located on another surface of the polarizing film or one surface of the first liquid crystal layer. The optical film according to claim 7 , wherein the auxiliary layer contains a vertically oriented liquid crystal. The second photoalignment film located on one surface of the first liquid crystal layer and
Further including a second liquid crystal layer located on one surface of the second photoalignment film,
The optical film according to claim 1, wherein the polarizing film, the first photoalignment film, the first liquid crystal layer, the second photoalignment film, and the second liquid crystal layer have an integrated structure in close contact with each other. The second photoalignment film is a coating composed of a photoreactive compound and a solution for a photoalignment film containing a solvent.
The optical film according to claim 9 , wherein the reaction product of the photoreactive compound is oriented in a predetermined direction with respect to the surface of the first liquid crystal layer. The first liquid crystal layer and the second liquid crystal layer are phase delay layers, respectively.
The optical film according to claim 9 , wherein the first liquid crystal layer and the second liquid crystal layer have different phase delays from each other. Any one of the first liquid crystal layer and the second liquid crystal layer has an in-plane phase difference of 230 nm to 300 nm with respect to a wavelength of 550 nm.
The optical film according to claim 11 , wherein the first liquid crystal layer and the other one of the second liquid crystal layers have an in-plane phase difference of 110 nm to 160 nm with respect to a wavelength of 550 nm. The optical film according to claim 9 , further comprising an auxiliary layer located on another surface of the polarizing film or one surface of the second liquid crystal layer. The optical film according to claim 13 , wherein the auxiliary layer includes a vertically oriented liquid crystal. A display device comprising the optical film according to any one of claims 1 to 14 . At the stage of preparing a polarizing film by melting and mixing polyolefin and dichroic dye,
The step of coating one surface of the polarizing film with a solution for a photoalignment film containing a photoreactive compound and a solvent, and
The step of drying the coated solution for a photoalignment film to form a first photoalignment film, and
Including a step of forming a first liquid crystal layer on one surface of the first photoalignment film.
A method for producing an optical film, wherein the solubility parameter of the polyolefin and the solvent satisfies the solubility parameter of the following relational expressions 1 to 3.
[Relationship formula 1]
_{0.9 ≦ │H D (P) -H} D (S) │ ≦ 1.7
[Relational expression 2]
_{1.9 ≦ │H P (P) -H} P (S) │ ≦ 4.1
[Relational expression 3]
4.9 ≤ │ _{H H} (P) -H _H (S) │ ≤ 10.8
In the relational expressions 1 to 3,
H _D (P) is the Hansen solubility parameter for dispersion force of the polyolefin (Hansen solubility parameter),
H D _(S) is the Hansen solubility parameter for dispersion force of said solvent,
H P _(P) is the Hansen solubility parameter for polarity of the polyolefin,
H P _(S) is the Hansen solubility parameter for polarity of the solvent,
H H _(P) is the Hansen solubility parameter for hydrogen bonding of the polyolefin,
H H _(S) is a Hansen solubility parameter for hydrogen bonding of the solvent. The method for producing an optical film according to claim 16 , wherein the photoreactive compound contains a photodimerized compound. The polyolefin contains polypropylene
The production of the optical film according to claim 16 , wherein the solvent contains any one of a propylene glycol monomethyl ether, a mixed solvent of propylene glycol monomethyl ether and toluene, and a mixed solvent of propylene glycol monomethyl ether and cyclohexanone. Method. At the stage of forming the second photoalignment film on one surface of the first liquid crystal layer,
The method for producing an optical film according to claim 16 , further comprising a step of forming a second liquid crystal layer on one surface of the second photoalignment film. The method for producing an optical film according to claim 16 , further comprising a step of forming an auxiliary layer on another surface of the polarizing film or one surface of the first liquid crystal layer.

Images