KR20210040374A - Optical film - Google Patents

Abstract

An object of the present invention is to provide an optical film having excellent film strength. An optical film having an optically anisotropic layer comprising a polymer polymerized in a state in which a polymerizable liquid crystal compound having one or more polymerizable functional groups is oriented, wherein the actual size is 0.3 µm or more and 50 µm or less. The optical film, characterized in that the number satisfies 0≦the number of alignment defects [number]≦14.

Description

Optical film

The present invention relates to an optical film, a retardation laminate, and a polarizing plate.

As an optical film used in a flat panel display, for example, an optical film having an optically anisotropic layer obtained by polymerization after applying a coating solution obtained by dissolving a polymerizable liquid crystal compound in a solvent on a supporting substrate has been proposed (Patent Document 1 ).

[Patent Document 1] Japanese Patent Laid-Open No. 2011-207765

In recent years, as the optical film becomes thinner, it is required to improve the film strength and workability of the optically anisotropic layer.

It is an object of the present invention to provide an optical film having improved film strength. Another object of the present invention is to provide an optical film having improved processability when processed into a polarizing plate.

The present invention provides the following aspects [1] to [12].

[1] An optical film having an optically anisotropic layer comprising a polymer polymerized in a state in which a polymerizable liquid crystal compound having at least one polymerizable functional group is oriented,

An optical film characterized in that the number of orientation defects having an actual size of 0.3 µm or more and 50 µm or less per 1 mm 2 of the optically anisotropic layer satisfies the following formula (1).

0≤number of orientation defects[pcs]≤14 (One)

[2] An optical film having an optically anisotropic layer comprising a polymer polymerized in a state in which a polymerizable liquid crystal compound having one or more polymerizable functional groups is oriented,

An optical film characterized in that the defect rate defined by the following formula (2) in the optically anisotropic layer satisfies the following formula (3).

[In the formula, the total defect area is the sum of the areas of orientation defects in which the actual size observed in one field of view of the optical microscope is 0.3 µm or more and 50 µm or less, and the observation field of the microscope is optically anisotropic in all one field of view of the optical microscope. It is the area of the optically anisotropic layer when the layer is present.]

0≤defect rate[ppm]≤1000 (3)

[3] An optical film having an optically anisotropic layer comprising a polymer polymerized in a state in which a polymerizable liquid crystal compound having at least one polymerizable functional group is oriented,

The number of orientation defects having an actual size of 0.3 µm or more and 50 µm or less per 1 mm 2 of the optically anisotropic layer satisfies the following formula (1), and the defect rate defined by the following formula (2) satisfies the following formula (3). Optical film, characterized in that.

0≤number of orientation defects[pcs]≤14 (One)

[In the formula, the total defect area is the sum of the areas of orientation defects in which the actual size observed in one field of view of the optical microscope is 0.3 µm or more and 50 µm or less, and the observation field of the microscope is optically anisotropic in all one field of view of the optical microscope. It is the area of the optically anisotropic layer when the layer is present.]

0≤defect rate[ppm]≤1000 (3)

[4] The optical film according to any one of [1] to [3], wherein the polymerizable functional group is an acryloyloxy group.

[5] The optical film according to any one of [1] to [4], wherein the alignment defect includes a defect caused by microcrystals of a polymerizable liquid crystal compound.

[6] The optical film according to any one of [1] to [5], wherein the thickness of the optically anisotropic layer is 0.05 µm or more and 10 µm or less.

[7] A phase difference laminate comprising one or more of the optical films described in any one of [1] to [6].

[8] A polarizing plate comprising the phase difference laminate according to [7].

[9] The polarizing plate according to [8] having a cut surface.

[10] The polarizing plate according to [8] or [9], which is a deformable polarizing plate.

[11] The polarizing plate according to any one of [8] to [10], comprising at least one of a front plate or a touch sensor.

[12] A flexible image display device comprising the polarizing plate according to any one of [8] to [11].

According to one aspect of the present invention, an optical film having improved film strength can be provided. Further, according to one aspect of the present invention, an optical film having improved processability can be provided.

1 is a schematic cross-sectional view showing an optical film according to an aspect of the present invention.
2 is a schematic cross-sectional view showing a phase difference laminate according to an aspect of the present invention.
3 is a schematic cross-sectional view showing a polarizing plate according to an aspect of the present invention.
4 is a schematic cross-sectional view showing a flexible image display device according to an aspect of the present invention.

[Optical film]

An optical film according to an aspect of the present invention is an optically anisotropic layer comprising a polymer polymerized in a state in which a polymerizable liquid crystal compound having one or more polymerizable functional groups (hereinafter, also simply referred to as a "polymerizable liquid crystal compound") is aligned. And the number of orientation defects (hereinafter also referred to as specific defects) having an actual size of 0.3 µm or more and 50 µm or less per 1 mm 2 of the optically anisotropic layer satisfies the following formula (1).

0≤number of orientation defects[pcs]≤14 (One)

The polymer polymerized while the polymerizable liquid crystal compound contained in the optically anisotropic layer is aligned is preferably polymerized while being aligned in one direction. The orientation may be horizontal orientation in which the optical axis of the polymerizable liquid crystal compound is oriented horizontally with respect to the plane of the optical film, or may be vertical orientation in which the optical axis of the polymerizable liquid crystal compound is oriented vertically with respect to the plane of the optical film. The optical axis means a direction in which a cross section cut out from a direction orthogonal to the optical axis becomes a circle in a refractive index ellipsoid formed by the orientation of a polymerizable liquid crystal compound, that is, a direction in which the refractive indexes of the two directions become the same.

The optically anisotropic layer can exhibit an in-plane retardation by polymerization in a state in which the polymerizable liquid crystal compound is oriented in an appropriate direction. When the polymerizable liquid crystal compound is a rod-shaped, in-plane retardation is expressed by horizontally aligning the optical axis of the polymerizable liquid crystal compound with respect to the plane of the optical film, and in this case, the optical axis direction and the slow axis direction coincide. When the polymerizable liquid crystal compound is disk-shaped, an in-plane retardation is expressed by horizontally aligning the optical axis of the polymerizable liquid crystal compound with respect to the optical film plane, and in this case, the optical axis and the slow axis are orthogonal. The alignment state of the polymerizable liquid crystal compound can be adjusted by a combination of an alignment film and a polymerizable liquid crystal compound described later.

As a polymerizable liquid crystal compound, a rod-shaped polymerizable liquid crystal compound and a disk-shaped polymerizable liquid crystal compound are exemplified. When the rod-shaped polymerizable liquid crystal compound is horizontally aligned or vertically aligned with respect to the plane of the optical film, the optical axis of the polymerizable liquid crystal compound coincides with the long axis direction of the polymerizable liquid crystal compound.

When the disk-type polymerizable liquid crystal compound is oriented, the optical axis of the polymerizable liquid crystal compound exists in a direction orthogonal to the disk surface of the polymerizable liquid crystal compound.

The polymerizable liquid crystal compound is a compound having at least one polymerizable functional group and also having liquid crystallinity. The polymerizable functional group means a group involved in the polymerization reaction, and a photopolymerizable group is preferable. Here, the photopolymerizable group refers to a group capable of participating in the polymerization reaction by an active radical or an acid generated from a photopolymerization initiator described later. Examples of the polymerizable functional group include epoxy group, vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, and the like. I can. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The liquid crystal properties of the polymerizable liquid crystal compound may be either a thermotropic liquid crystal or a lyotropic liquid crystal, and if the thermotropic liquid crystal is classified in order, nematic liquid crystal or smectic liquid crystal may be used. The polymerizable liquid crystal compound preferably has two or more polymerizable functional groups, and more preferably has two polymerizable functional groups.

It is preferable that the polymerizable liquid crystal compound has a molecular weight of 250 or more for one polymerizable functional group. For example, when the polymerizable liquid crystal compound has two polymerizable functional groups, the molecular weight of the polymerizable liquid crystal compound may be 500 or more. When the polymerizable liquid crystal compound has a molecular weight of 250 or more with respect to one polymerizable functional group, it tends to be easy to obtain good liquid crystallinity. The polymerizable liquid crystal compound has a molecular weight of preferably 280 or more, more preferably 300 or more, still more preferably 400 or more, and usually 1000 or less with respect to one polymerizable functional group.

The molecular weight of the polymerizable liquid crystal compound is preferably 500 or more, more preferably 560 or more, still more preferably 600 or more, further preferably 800 or more, and usually 2000 or less and may be 1500 or less. The polymerizable liquid crystal compound tends to be difficult to crystallize as the molecular weight decreases. Therefore, from the viewpoint of reducing specific defects caused by microcrystals, a polymerizable liquid crystal compound having a small molecular weight is preferably used. On the other hand, the larger the molecular weight of the polymerizable liquid crystal compound is, the easier it is to crystallize, and there is a tendency for an orientation defect resulting from crystallization to increase. In the case of using a polymerizable liquid crystal compound having a relatively large molecular weight, such as 500 or more, in order to make the number of specific defects within the range specified in the present invention, for example, by using a combination of two or more liquid crystal compounds as a polymerizable liquid crystal compound, It can be made into a polymer, or the humidity at the time of coating a polymeric liquid crystal compound on a base material can be comparatively lowered.

As a rod-shaped polymerizable liquid crystal compound or a disk-shaped polymerizable liquid crystal compound, known ones can be used. For example, "3.8.6 Network (published on October 30, 2000) of the Liquid Crystal Handbook (Liquid Crystal Handbook Editing Committee edition, Maruzen Co., Ltd.)) Complete crosslinking type)", "6.5.1 Liquid crystal material b. Polymerizable nematic liquid crystal material”, a compound having a polymerizable group, Japanese Patent Laid-Open No. 2011-207765, Japanese Patent Laid-Open No. 2010-24438, Japanese Patent Laid-Open No. 2015-163937, Japanese Patent Laid-Open 2017-179367 The compounds exemplified in Japanese Unexamined Publication No. 2016-42185, International Publication No. 2016/158940, and Japanese Unexamined Patent Publication No. 2016-224128 can be used. The optically anisotropic layer may contain only one type of polymer of the polymerizable liquid crystal compound, or may contain two or more types of polymers.

In recent years, a thinned optical film has been demanded, and a thin film is also required for an optically anisotropic layer containing a polymer of a polymerizable liquid crystal compound. However, the optically anisotropic layer having a thin thickness and in which the polymer of the polymerizable liquid crystal compound is oriented in one direction tends to be very fragile, and the film strength tends to be low. As a result of research on the improvement of the film strength of an optical film by the present inventors, the optically anisotropic layer containing a polymer polymerized in a state in which the polymerizable liquid crystal compound is oriented has the film strength and workability and the number of alignment defects in the optically anisotropic layer. It can be seen that there is a correlation between The inventor of the present invention, paying attention to it, further studied, and found that the smaller the number of the above-described specific defects in the optically anisotropic layer, the better the film strength of the optical film tends to be, and the number of specific defects is determined by the above equation ( It was found that when 1) is satisfied, the film strength and workability of the optically anisotropic layer tend to be improved. Obviously, the optical film ideally and preferably has zero specific defects, but it is difficult to produce an optically anisotropic layer having zero specific defects. Therefore, it is presumed that a specific defect is usually present in an optical film, and the stress generated in the optical film when using or processing an optical film having a specific defect is concentrated on the specific defect, and the optical film is broken or burst. For this reason, when the number of specific defects present in the optically anisotropic layer containing a polymer in which a polymerizable liquid crystal compound having a specific molecular weight is oriented is small, the portion where the stress is concentrated is reduced, and as a result, the optical film is broken or burst. It becomes difficult to do this, and it is thought that workability of an optical film improves.

A specific defect is a region in which an alignment defect of the polymerizable liquid crystal compound has occurred, and is observed as a bright spot under a cross-Nichol state under an optical microscope. Specific defects may include defects caused by microcrystals and gels of the polymerizable liquid crystal compound, foreign substances, splashes or irregularities in the coating film of the polymerizable liquid crystal compound, poor alignment film, irregularities or scratches on the base material, contamination of the base material, and the like.

Specific defects have an actual size of 0.3 µm or more and 50 µm or less. The actual size refers to a value obtained by measuring the length of a portion where the dimension becomes the largest with respect to the appearance of a defect that is visually recognized when the bright spot is observed by releasing the cross-Nicol state of an optical microscope. For example, when the appearance of a defect is visually recognized as a circular shape, the actual size is the length of the circular diameter. For example, when the appearance of a defect is visually recognized as a square, the actual size is the length of the diagonal of the square. When the actual size of the defect is less than 0.3 µm, there is a tendency that it is difficult to observe as a bright spot under a cross-Nichol condition under an optical microscope. When the actual size of the defect exceeds 50 µm, it becomes easy to be visually recognized, and the optical film tends to be unusable due to poor appearance. Defects having an actual size of 0.3 µm or more and 50 µm or less have not been recognized as bright spots because conventionally, the polarization degree of the polarizing plate is lower than the present, and tends to be difficult to observe as bright spots under the cross-Nicol state of an optical microscope. However, in recent years, from the viewpoint of further improvement in quality, reduction of such defects has been demanded. The number of defects whose actual size exceeds 50 µm is ideal and preferable, but may exist as long as the number of defects does not affect the appearance, film strength, and workability of the optical film, and usually 3 pieces/mm 2 It is less than or equal to 5 pieces/mm2 or 6 pieces/mm2 even if it is many. In addition, defects having an actual size of more than 50 µm are mostly caused by foreign substances.

The actual size may be, for example, 0.5 µm or more, 1 µm or more, or 5 µm or more. On the other hand, the actual size may be, for example, 40 µm or less, 30 µm or less, or 20 µm or less.

The average value of the actual size obtained by observing the optical film may be, for example, 0.5 µm or more, 1 µm or more, or 5 µm or more. On the other hand, the average value of the actual size may be, for example, 40 µm or less, 30 µm or less, or 20 µm or less.

In order for the number of specific defects to satisfy the formula (1), for example, adjustment of the composition of the liquid crystal composition to be described later that constitutes the optically anisotropic layer, adjustment of manufacturing conditions, or a combination thereof can be performed.

When adjusting the composition of the liquid crystal composition, for example, in the liquid crystal composition, the proportion of the polymerizable liquid crystal compound, the proportion of the poorly soluble polymerizable liquid crystal compound, the solid content concentration, and the like can be adjusted.

The liquid crystal composition may preferably contain two or more kinds of polymerizable liquid crystal compounds, and may contain three or more kinds of polymerizable liquid crystal compounds from the viewpoint of reducing specific defects caused by microcrystals in the optically anisotropic layer. The upper limit of the type of the polymerizable liquid crystal compound included in the liquid crystal composition may be, for example, 20 types. When the liquid crystal composition contains two or more kinds of polymerizable liquid crystal compounds, when the mass ratio of the polymerizable liquid crystal compound serving as the main polymer is high, crystals of the polymerizable liquid crystal compound tend to precipitate easily. Therefore, when the mass ratio of the polymerizable liquid crystal compound which is the main polymeric liquid crystal compound in the liquid crystal composition is lowered, the number of specific defects caused by microcrystals tends to decrease. When the liquid crystal composition contains two or more kinds of polymerizable liquid crystal compounds, the polymerizable liquid crystal compound serving as the main in the liquid crystal composition may be, for example, 90 mass% or less, preferably 85 mass% or less with respect to the total amount of the polymerizable liquid crystal compound. to be. Microcrystalline refers to crystals, crystal grains, and aggregates thereof having a size of several nm or more and hundreds of µm or less. The "polymerizable liquid crystal compound serving as a main" means a polymerizable liquid crystal compound having the largest content ratio among the polymerizable liquid crystal compounds contained in the liquid crystal composition.

As described above, the larger the molecular weight of the polymerizable liquid crystal compound is, the easier it is to crystallize, and there is a tendency that specific defects caused by microcrystals increase. For this reason, in the case of using a polymerizable liquid crystal compound having a relatively large molecular weight, such as a polymerizable liquid crystal compound having a molecular weight of 500 or more, in order to make the number of alignment defects within the range specified in the present invention, for example, two or more types of polymerizable liquid crystal compounds are used. Polymerization can be performed by combining a liquid crystal compound.

Specifically, the liquid crystal composition preferably contains two or more polymerizable liquid crystal compounds having a molecular weight of 600 or more, more preferably three or more, and may contain 20 or less. The liquid crystal composition preferably contains two or more polymerizable liquid crystal compounds having a molecular weight of 800 or more, more preferably three or more, and may contain 10 or less. In these cases, the liquid crystal composition may include a polymerizable liquid crystal compound having a molecular weight of less than 800, and further less than 600.

When the liquid crystal composition contains a poorly soluble polymerizable liquid crystal compound, crystals of the poorly soluble polymerizable liquid crystal compound tend to precipitate. Therefore, when the mass ratio of the poorly soluble liquid crystal composition is reduced or the mass ratio of the polymerizable liquid crystal compound is increased, the number of specific defects caused by microcrystals tends to decrease. When the liquid crystal composition contains a poorly soluble polymerizable liquid crystal compound, the poorly soluble polymerizable liquid crystal compound in the liquid crystal composition may be, for example, 90% by mass or less, preferably 85% by mass with respect to the total amount of the polymerizable liquid crystal compound. Below.

In the liquid crystal composition, when the amount of the solvent is increased to lower the solid content, crystals of the polymerizable liquid crystal compound become difficult to precipitate, and the number of specific defects caused by microcrystals tends to decrease. In addition, when the amount of the solvent is increased and the solid content is lowered, the solvent in the coating film becomes difficult to completely volatilize, so that crystals of the polymerizable liquid crystal compound are difficult to precipitate, and the number of specific defects caused by microcrystals tends to decrease. The solid content of the liquid crystal composition may be, for example, 50% by mass or less, and preferably 25% by mass or less.

To the liquid crystal composition, a monomer other than a polymerizable liquid crystal compound (e.g., a low molecular weight monomer such as acrylate or methacrylate) or a polymer (e.g., a polymer such as polyvinyl alcohol or polyethylene glycol and a modified product thereof) is added, or a polymerizable liquid crystal Even if some or all of the compounds are made into dimers, trimers or more oligomers before orientation and polymerization of the compound, the number of specific defects caused by microcrystals tends to decrease. When the liquid crystal composition contains a monomer or polymer other than the polymerizable liquid crystal compound, or a dimer, trimer or higher oligomer of the polymerizable liquid crystal compound, the solubility in the solvent is improved, and the precipitation of crystals tends to be easily suppressed. have.

When adjusting the manufacturing conditions, for example, the temperature of the substrate when coating the liquid crystal composition, the humidity of the ambient atmosphere during coating, the ambient atmosphere of the die used for coating, and the like can be adjusted.

The substrate to which the liquid crystal composition is applied tends to reduce the number of specific defects caused by microcrystals by keeping it warm at a constant temperature when the liquid crystal composition is applied. The temperature to keep warm may be, for example, 15°C or more and 60°C or less, and preferably 20°C or more and 50°C or less.

By using a substrate having good surface smoothness, the uniformity of the coating film of the polymerizable liquid crystal compound is improved, and the number of specific defects due to spatter of the coating film of the polymerizable liquid crystal compound or defective alignment film tends to decrease. As a means to increase the smoothness of the substrate surface, for example, annealing (surface grinding) or the like can be mentioned. Annealing can be performed by heating the substrate, and the heating temperature may be, for example, 60° C. or higher and 100° C. or lower, or 5° C. to 20° C. lower than the glass transition point of the substrate, and the heating time is, for example, 1 second or more and 60 seconds or less. It can be done.

By making the humidity of the surrounding atmosphere constant during coating, it becomes easy to suppress crystallization of the polymerizable liquid crystal compound, and the number of specific defects caused by microcrystals tends to decrease. The humidity of the surrounding atmosphere during coating may be, for example, 90%RH or less, preferably 85%RH or less, more preferably 60%RH or less, still more preferably 55%RH or less, and particularly preferably 40% It is less than or equal to RH. On the other hand, the humidity of the surrounding atmosphere during coating may be, for example, 10%RH or more, and preferably 20%RH or more. In the case of using a polymerizable liquid crystal compound having a relatively large molecular weight, in order to make the number of specific defects within the range specified in the present invention, the humidity when the polymerizable liquid crystal compound is applied onto a substrate can be relatively lowered.

By adjusting the atmosphere around the die used for coating by the vapor pressure of the solvent contained in the polymerizable liquid crystal compound (under the solvent atmosphere), the solvent of the polymerizable liquid crystal compound becomes difficult to volatilize, and crystallization of the polymerizable liquid crystal compound is suppressed, and microcrystalline The number of specific defects caused by the tends to be small.

By removing contamination of the substrate surface, such as PET lubricant, PET oligomer, silicone oil, etc., before coating of the liquid crystal composition, the number of specific defects caused by foreign matter tends to decrease. Further, by applying the liquid crystal composition in a clean room having a high degree of cleanliness, the number of specific defects caused by foreign matter tends to decrease. Further, by removing foreign matters, microcrystals, and the like in the liquid crystal composition before coating with a filter, the number of microcrystals and specific defects caused by foreign matter tends to decrease.

The number of specific defects per 1 mm 2 of the optically anisotropic layer is preferably 10 or less, more preferably 7 or less, still more preferably 6 or less, particularly preferably 3 or less, and particularly preferably 1 or less. to be. Further, the number of specific defects per 1 mm 2 of the optically anisotropic layer is ideally 0, but may be 0.001 or more, and further, 0.01 or more.

The ratio of the number of defects due to microcrystals in the number of specific defects per 1 mm 2 of the optically anisotropic layer may be, for example, 70% or more, or 85% or more, and preferably 90% or more. In the case of microcrystallization, if microcrystals are present in the optically anisotropic layer, it is estimated that when stress is applied, the crystal portion becomes a stress concentration point and is destroyed. Therefore, when 70% or more of the specific defects are due to microcrystals, the number of specific defects due to microcrystals is 14 or less, and the stress is appropriately distributed in the thickness of the optically anisotropic layer of the present invention, and the film strength is increased. It is estimated to be.

The ratio of the number of defects due to foreign substances in the number of specific defects per 1 mm 2 of the optically anisotropic layer may be, for example, 10% or less or 0%.

The ratio of the number of defects caused by spatter in the number of specific defects per 1 mm 2 of the optically anisotropic layer may be, for example, 10% or more and 70% or less, or 20% or more and 60% or less.

The film strength of the optically anisotropic layer can be evaluated according to the measurement method of the piercing strength described in the Examples section described later. The piercing strength of the optical film may be, for example, 5 gmm or more and 100 gmm or less, preferably 10 gmm or more and 80 gmm or less, and more preferably 15 gmm or more and 50 gmm or less. When the piercing strength of the optical film is within the above range, even when the optical film is thinned, there is a tendency that good film strength is easily obtained.

The film strength of the optically anisotropic layer can be evaluated according to the measurement method of the piercing strength described in the Examples section described later. The piercing strength of the optical film may be, for example, 5 g·mm or more and 100 g·mm or less, preferably 10 g·mm or more and 80 g·mm or less, and more preferably 15 g·mm or more and 50 g·mm or less. When the piercing strength of the optical film is within the above range, even when the optical film is thinned, there is a tendency that good film strength is easily obtained.

The film strength of the optically anisotropic layer can also be evaluated according to the measuring method of tensile stress described in the Examples section described later. The tensile stress of the optical film may be, for example, 30 N/mm 2 or more and 200 N/mm 2 or less, preferably 40 N/mm 2 or more and 150 N/mm 2 or less, and more preferably 50 N/mm 2 or more and 100 N/mm 2 or less. When the tensile stress of the optical film is within the above range, even when the optical film is thinned, it tends to become easy to obtain good film strength.

The optical film may further have a base layer and an alignment layer in addition to the optically anisotropic layer.

The base material layer can be constituted of, for example, a resin film or the like. The resin constituting the resin film is a light-transmitting thermoplastic resin, preferably an optically transparent thermoplastic resin, and examples thereof include polyolefin resins such as polyethylene and polypropylene; Cyclic polyolefin-based resins such as norbornene-based polymers; Polyester resins such as polyethylene terephthalate and polyethylene naphthalate; (Meth)acrylic acid-based resins such as (meth)acrylic acid and poly(meth)methyl acrylate; Cellulose ester resins such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; Vinyl alcohol-based resins such as polyvinyl alcohol and polyvinyl acetate; Polycarbonate resin; Polystyrene resin; Polyarylate resin; Polysulfone resin; Polyethersulfone resin; Polyamide resin; Polyimide resin; Polyether ketone resin; Polyphenylene sulfide resin; And polyphenylene oxide-based resins and mixtures and copolymers thereof. Among these resins, it is preferable to use any one of a cyclic polyolefin resin, a polyester resin, a cellulose ester resin, and a (meth)acrylic acid resin, or a mixture thereof.

The thickness of the substrate layer may be, for example, 1 µm or more and 300 µm or less, and preferably 5 µm or more and 200 µm or less, and more preferably 10 µm or more and 120 µm or less from the viewpoint of workability such as strength and handling.

The heat capacity per 1 cm 2 of the substrate layer is not particularly limited, but it is preferable to control the temperature of the optical film by an environmental temperature control device such as a drying furnace or a cooling furnace. This is 0.1 J/cm2·°C or less, more preferably 0.05 J/cm2·°C or less, and particularly preferably 0.03 J/cm2·°C or less.

Here, the heat capacity per 1 cm 2 of the base layer refers to the heat capacity of the volume contained when the base layer is cut out by 1 cm 2.

Further, the specific heat of the substrate layer is not particularly limited, but from the same viewpoint, 2,000 J/kg·° C. or less is preferable, and 1,500 J/kg·° C. or less is more preferable.

When the optical film has a substrate layer and an alignment layer, in order to improve the adhesion between the substrate layer and the alignment layer, corona treatment, plasma treatment, flame treatment, etc. may be performed on the surface of the substrate layer on which the alignment layer is formed. , A primer layer or the like may be formed.

The alignment layer has an alignment regulating force for liquid crystal alignment of the polymerizable liquid crystal compound in a desired direction. Examples of the alignment layer include an alignment polymer layer formed of an alignment polymer, a photo-alignment polymer layer formed of a photo-alignment polymer, and a groove alignment layer having an uneven pattern or a plurality of grooves (grooves) on the surface of the layer, and the thickness of the alignment layer is usually It is 10 nm or more and 4000 nm or less, and it is preferable that it is 50 nm or more and 3000 nm or less.

The oriented polymer layer can be formed by applying a composition in which the oriented polymer is dissolved in a solvent to the base layer to remove the solvent, and performing rubbing treatment as necessary. In this case, the orientation regulating force can be arbitrarily adjusted in the orientation polymer layer formed of the orientation polymer in accordance with the surface condition and rubbing conditions of the orientation polymer.

The photo-alignment polymer layer can be formed by applying a polymer having a photoreactive group or a composition containing a monomer and a solvent (hereinafter, also referred to as a composition for forming a photo-alignment film) to a base layer and irradiating light such as ultraviolet rays. In particular, when the orientation-regulating force is expressed in the horizontal direction, it can be formed by irradiating polarized light. In this case, the orientation regulating force can be arbitrarily adjusted in the photo-alignment polymer layer by polarization irradiation conditions for the photo-alignment polymer or the like.

The groove alignment layer is, for example, a method of forming an uneven pattern by performing exposure, development, etc. through an exposure mask having a pattern-shaped slit on the surface of a photosensitive polyimide film, and an active energy ray on a plate-shaped disk having a groove on the surface. A method of forming an uncured layer of curable resin, transferring the layer to the substrate layer to cure, forming an uncured layer of active energy ray-curable resin on the substrate layer, and pressing the roll-shaped disc having irregularities on this layer. It can be formed by a method of forming unevenness and hardening by, for example.

When the optical film includes a substrate layer and an alignment layer, when peeling the substrate layer, the alignment layer may be peeled off together with the substrate layer, and the alignment layer may remain on the optically anisotropic layer. Whether the alignment layer is peeled off with the base layer or remains in the optically anisotropic layer can be set by adjusting the relationship of the adhesion between each layer, for example, the above-described corona treatment, plasma treatment, flame treatment, and primer applied to the base layer. It can be adjusted by surface treatment such as a layer or a component of a liquid crystal composition used to form an optically anisotropic layer.

The optical film according to another aspect of the present invention is an optical film having an optically anisotropic layer comprising a polymer polymerized in a state in which a polymerizable liquid crystal compound having one or more polymerizable functional groups is oriented, and the following in the optically anisotropic layer The defect rate defined by formula (2) is characterized by satisfying the following formula (3).

[In the formula, the total defect area is the sum of the areas of defects whose actual size observed in one field of view of the optical microscope is 0.3 µm or more and 50 µm or less, and the microscope observation field is observed in one field of view of the optical microscope. It is the area of the optically anisotropic layer.]

0≤defect rate[ppm]≤1000 (3)

The microscopic observation field in Formula (2) may be, for example, 4.53 mm 2. The defect rate can be determined according to the method of measuring the defect rate described in the Examples section to be described later.

When the defect rate of the optically anisotropic layer satisfies the formula (3), there is a tendency that the film strength and workability of the optically anisotropic layer are easily made good. The defect rate of the optically anisotropic layer is preferably 600 ppm or less, more preferably 300 ppm or less, still more preferably 100 ppm or less, particularly preferably 50 ppm or less from the viewpoint of the film strength and processability of the optically anisotropic layer. . The defect rate of the optically anisotropic layer is ideally 0 ppm, but may be 0.01 ppm or more, and further, 0.1 ppm or more.

In order for the defect rate of the optically anisotropic layer to satisfy the formula (3), it can be performed by, for example, selection of the kind or molecular weight of the polymerizable liquid crystal compound, control of the composition, control of production conditions, and combinations thereof. Specific examples of the control of the type, molecular weight, and composition of the polymerizable liquid crystal compound, and the control of the manufacturing conditions, are the number of defects whose actual size is 0.3 µm or more and 50 µm or less per 1 mm 2 of the above-described optically anisotropic layer satisfies Equation (1). In order to do so, what is illustrated is suitable.

An optical film according to another aspect of the present invention is an optical film having an optically anisotropic layer comprising a polymer polymerized in a state in which a polymerizable liquid crystal compound having one or more polymerizable functional groups is oriented, per 1 mm 2 of the optically anisotropic layer , The number of defects having an actual size of 0.3 µm or more and 50 µm or less satisfies the following formula (1), and the defect rate defined by the following formula (2) satisfies the following formula (3).

0≤number of orientation defects[pcs]≤14 (One)

0≤defect rate[ppm]≤1000 (3)

[In the formula, the total defect area is the sum of the areas of defects whose actual size observed in one field of view of the optical microscope is 0.3 µm or more and 50 µm or less, and the observation field of the microscope is optical anisotropy observed in one field of view of the optical microscope. It is the area of the floor.]

When the number of defects whose actual size is 0.3 µm or more and 50 µm or less per 1 mm2 of the optically anisotropic layer satisfies Equation (1) and the defect rate satisfies Equation (3), the film strength and workability of the optically anisotropic layer are excellent. It tends to be easy to do.

The optical film is excellent in transparency, and can be used in a variety of uses together with a substrate and/or alignment film or various optical films in a single single layer or laminated structure (for example, a structure of two or more and four or less layers). In addition, when a plurality of layers are laminated, the same film may be used, or different layers may be used in combination. Here, the optical film refers to a film that can transmit light, and refers to a film having an optical function, and the optical function refers to refraction, birefringence, and the like.

As an optical film, for example

First form: a retardation film in which a rod-shaped liquid crystal compound is oriented in a horizontal direction with respect to a supporting substrate,

Second form: a retardation film in which a rod-shaped liquid crystal compound is oriented in a vertical direction with respect to a supporting substrate,

Third form: a retardation film in which a rod-shaped liquid crystal compound is helically changed in an orientation direction in a plane,

Fourth aspect: a retardation film in which a disc-shaped liquid crystal compound is obliquely aligned,

Fifth form: a biaxial retardation film in which a disc-shaped liquid crystal compound is oriented in a vertical direction with respect to a supporting substrate

Can be mentioned.

The optical film may have a retardation value (Re (550 nm) at a wavelength of 550 nm) of, for example, 113 nm or more and 163 nm or less, preferably 130 nm or more and 150 nm or less, and more preferably about 135 nm or more and 150 nm. Below. When the optical film has a retardation value at a wavelength of 550 nm in the above range, it is suitable for a 1/4 wavelength retardation film.

It is preferable that the optical film has reverse wavelength dispersion. The reverse wavelength dispersion is an optical characteristic in which the phase difference value in the liquid crystal alignment at a short wavelength becomes smaller than the phase difference value in the liquid crystal alignment at a long wavelength, and the optical film preferably satisfies the following formulas (i) and (ii). will be.

In addition, Re(λ) represents an in-plane retardation value for light having a wavelength of λ nm.

Re(450)/Re(550)≤1 (i)

1≤Re(630)/Re(550) (ii)

When the optical film is the first aspect described above and has reverse wavelength dispersion, it is preferable because the coloration at the time of black display in the display device is reduced, and in equation (1), 0.82 ≤ Re(450)/ It is more preferable if Re(550)≤0.93. Further, 120≦Re(550)≦150 is preferable.

When the optical film is of the second form, the in-plane retardation value Re(550) may be adjusted in the range of 0 to 10 nm, preferably in the range of 0 to 5 nm, and the retardation value R _th in the thickness direction is- The range of 10 to -300 nm, preferably -20 to -200 nm.

_{The retardation value R th} in the thickness direction, which means refractive index anisotropy in the thickness direction, can be calculated from the _{retardation value R 50} and the in-plane retardation value R _{e, which} are measured by inclining the in-plane fast axis by 50 degrees as the inclined axis. _{That is, the retardation value R th} in the thickness direction is from the in-plane _{retardation value R e , the retardation value R 50} measured by inclining the fast axis by 50 degrees, the thickness d of the retardation film, and the average refractive index n _{0 of the retardation film. It can be calculated by obtaining n x} , n _y and n _z by equations (iv) to (vi) of, and substituting them into equation (iii).

R _th =[(n _x +n _y )/2-n _z ]×d (iii)

R _e =(n _x -n _y )×d (iv)

R ₅₀ =(n _x -n _y ')×d/cos(φ) (v)

(n _x +n _y +n _z )/3=n ₀ (vi)

here,

φ=sin ^-1 〔sin(40°)/n ₀ 〕

n _y '= n _y × n _z / (n _y ² ×sin ² (φ)+n _z ² ×cos ² (φ)) ^1/2

In order to use the optical film as an optical film for VA (Vertical Alingment) mode, the content of the polymerizable liquid crystal compound in the liquid crystal composition may be appropriately adjusted to adjust the thickness of the optical film. Specifically, the film thickness may be adjusted so that Re(550) is, for example, 40 nm or more and 100 nm or less, preferably 60 nm or more and 80 nm or less.

[Manufacturing method of optical film]

An optical film can be produced, for example, by preparing a liquid crystal composition, then coating a liquid crystal composition on a substrate or an alignment film, drying, and polymerizing a polymerizable liquid crystal compound.

<Liquid Crystal Composition>

The liquid crystal composition can be prepared by optionally mixing a polymerizable liquid crystal compound with a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, and/or a leveling agent.

The larger the molecular weight of the polymerizable liquid crystal compound is, the easier it is to crystallize, and since there is a tendency that specific defects due to microcrystals tend to increase, in the case of using a polymerizable liquid crystal compound having a relatively large molecular weight, the number of specific defects is within the range defined in the present invention. In order to set it as, for example, as a polymerizable liquid crystal compound, polymerization can be performed by combining two or more types of liquid crystal compounds.

(Polymerizable liquid crystal compound)

As a polymerizable liquid crystal compound, for example, Japanese Patent Laid-Open No. 2011-207765, Japanese Patent Laid-Open No. 2010-24438, Japanese Patent Laid-Open No. 2015-163937, Japanese Patent Laid-Open No. 2017-179367, Japanese Patent Laid-Open No. 2016-42185 , International Publication No. 2016/158940, Japanese Patent Publication No. 2016-224128, and the like may be used alone or in combination of two or more. The polymerizable liquid crystal compound has one or more polymerizable functional groups, preferably two or more polymerizable functional groups, more preferably two or more and four or less polymerizable functional groups, and more preferably two polymerization functional groups. It has a sexual functional group.

The polymerizable liquid crystal compound may have a molecular weight of, for example, 250 or more with respect to one polymerizable functional group. For example, when the polymerizable liquid crystal compound has two polymerizable functional groups, the molecular weight of the polymerizable liquid crystal compound may be 500 or more, 600 or more, or 800 or more. When the polymerizable liquid crystal compound has a molecular weight of 250 or more with respect to one polymerizable functional group, it tends to be easy to obtain good liquid crystallinity. The polymerizable liquid crystal compound has a molecular weight of preferably 280 or more, more preferably 300 or more, still more preferably 400 or more, and usually 1000 or less with respect to one polymerizable functional group.

The molecular weight of the polymerizable liquid crystal compound is preferably 500 or more, more preferably 560 or more, still more preferably 600 or more, further preferably 800 or more, usually 2000 or less, and may be 1500 or less.

Examples of the polymerizable liquid crystal compound include compounds satisfying all of the following (1) to (4).

(1) It is a compound capable of forming a nematic phase.

(2) It has π electrons on the major axis direction (a) of the polymerizable liquid crystal compound.

(3) It has π electrons in the direction [crossing direction (b)] that intersects with the major axis direction (a).

(4) The long axis of the polymerizable liquid crystal compound defined by the following formula (i) with the sum of the π electrons present in the major axis direction (a) as N(πa) and the total molecular weights in the major axis direction as N(Aa) Π electron density in direction (a):

D(πa)=N(πa)/N(Aa) (i)

And, a polymerizable liquid crystal compound defined by the following formula (ii), with the sum of the π electrons present in the crossing direction (b) being N(πb) and the molecular weights present in the crossing direction (b) as N(Ab) Π electron density in the crossing direction (b) of:

D(πb)=N(πb)/N(Ab) (ii)

Is 0≦[D(πa)/D(πb)]≦1 (that is, the π electron density in the crossing direction b is greater than the π electron density in the major axis direction a).

Further, the polymerizable liquid crystal compound that satisfies all of the above (1) to (4) can be applied onto an alignment film, for example, and heated to a phase transition temperature or higher to form a nematic phase. In the nematic phase formed by aligning this polymerizable liquid crystal compound, the major axis directions of the polymerizable liquid crystal compound are usually oriented so that they are parallel to each other, and this major axis direction becomes the orientation direction of the nematic phase.

Since the compound satisfying the above (3) has π electrons in the crossing direction (b), it tends to be easily crystallized by π-π interaction. According to this embodiment, even when such a polymerizable liquid crystal compound is used, the number of specific defects caused by microcrystals can be reduced.

The polymerizable liquid crystal compound having the above characteristics generally exhibits reverse wavelength dispersion in many cases. As a compound satisfying the characteristics of the above (1) to (4), specifically, for example, the following formula (I):

The compound represented by is mentioned.

In formula (I), Ar represents a divalent aromatic group which may have a substituent. The aromatic group referred to herein is a cyclic structure having planarity, and the number of π electrons in this cyclic structure is [4n+2] according to Huckel's rule. Where n represents an integer. When a ring structure is formed by including a hetero atom such as -N= or -S-, the Huckel rule is satisfied by including a pair of non-covalent bonded electrons on these hetero atoms, and a case of having aromaticity is also included. It is preferable that at least one of a nitrogen atom, an oxygen atom, and a sulfur atom is contained in the divalent aromatic group.

Each of G ¹ and G ² independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group.

Here, the hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group is a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or It may be substituted with a nitro group, and the carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom.

L ¹ , L ² , B ¹ and B ² are each independently a single bond or a divalent linking group.

Each of k and l independently represents an integer of 0 to 3, and satisfies the relationship of 1≦k+l. Here, when 2≦k+l, B ¹ and B ² , G ¹ and G ² may be the same or different from each other.

E ¹ and E ² each independently represent an alkanediyl group having 1 to 17 carbon atoms, wherein the hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and -CH ₂ -contained in the alkanediyl group May be substituted with -O-, -S-, or -Si-.

P ¹ and P ² each independently represent a polymerizable functional group or a hydrogen atom, and at least one is a polymerizable functional group.

Each of G ¹ and G ² is independently preferably a 1,4-phenylenediyl group, a halogen atom and a C 1 to C 1, which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms. It is a 1,4-cyclohexanediyl group which may be substituted with at least one substituent selected from the group consisting of 4 alkyl groups, more preferably a 1,4-phenylenediyl group substituted with a methyl group, an unsubstituted 1,4 -Phenylenediyl group or an unsubstituted 1,4-trans-cyclohexanediyl group, and particularly preferably an unsubstituted 1,4-phenylenediyl group or an unsubstituted 1,4-trans-cyclohexanediyl group.

In addition, it is preferable that at least one of the ^{plurality of G 1} and G ^{2 is a divalent alicyclic hydrocarbon group, and at least one of G 1} and G ² bonded to ^{L 1} or L ² is a divalent alicyclic hydrocarbon group. desirable.

L ¹ and L ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a1 OR ^a2 -, -R ^a3 COOR ^a4 -, -R ^a5 OCOR ^a6 -, R ^a7 OC=OOR ^a8 -, -N=N-, ^{-CR c} =CR ^d -or C≡C-. Here, R ^a1 to ^{R a8} each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms, and R ^c and R ^{d each} represent a C 1 to C 4 alkyl group or a hydrogen atom. L ¹ and L ² are each independently more preferably a single bond, -OR ^{a2 -1} -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a4-1 -or OCOR ^{a6 -1} -. Here, R ^{a2 -1} , R ^{a4 -1} , and R ^{a6 -1} each independently represent a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. L ¹ and L ² are each independently more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -or OCO-.

B ¹ and B ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a9 OR ^a10 -, -R ^a11 COOR ^a12 -, -R ^a13 OCOR ^{a14 -Or} R a15 OC=OOR ^a16 -. Here, R ^a9 to ^{R a16} each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms. B ¹ and B ² are each independently more preferably a single bond, -OR ^{a10 -1} -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a12-1 -or OCOR ^{a14 -1} -. Here, R ^{a10 -1} , R ^{a12 -1} , and R ^{a14 -1} each independently represent a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. B ¹ and B ² are each independently more preferably a single _{bond, -O-, -CH 2 CH 2 -} , -COO-, -COOCH 2 CH 2 -, -OCO- , or OCOCH ₂ CH ₂ - it is.

From the viewpoint of expressing reverse wavelength dispersion, k and 1 are preferably in the range of 2≦k+l≦6, preferably k+l=4, and more preferably k=2 and 1=2. When k=2 and l=2, a symmetrical structure is obtained, which is preferable.

E ¹ and E ² are each independently preferably an alkanediyl group having 1 to 17 carbon atoms, more preferably an alkanediyl group having 4 to 12 carbon atoms.

Examples of ^{the polymerizable functional group represented by P 1} or P ² include epoxy group, vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxira And an oxetanyl group.

Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and an acryloyloxy group is more preferable.

Ar preferably has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle which may have a substituent, and an electron withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, an anthracene ring, and the like, and a benzene ring and a naphthalene ring are preferable. Examples of the aromatic heterocycle include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, and an imidazole ring. , A pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Among them, those having a thiazole ring, a benzothiazole ring, or a benzofuran ring are preferred, and those having a benzothiazole group are more preferred. In addition, when Ar contains a nitrogen atom, it is preferable that the nitrogen atom has π electrons.

In formula (I), the total number Nπ of π electrons contained in the divalent aromatic group represented by Ar is preferably 8 or more, more preferably 10 or more, still more preferably 14 or more, and particularly preferably 16 That's it. Further, it is preferably 30 or less, more preferably 26 or less, and still more preferably 24 or less.

As an aromatic group represented by Ar, the following groups are mentioned, for example.

In formulas (Ar-1) to (Ar-23), * represents a connecting portion, and Z ⁰ , Z ¹ and Z ² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, Nitro group, C1-C12 alkylsulfinyl group, C1-C12 alkylsulfonyl group, carboxyl group, C1-C12 fluoroalkyl group, C1-C6 alkoxy group, C1-C12 alkylthio group, C1-C12 1 to 12 N-alkylamino group, C 2 to C 12 N,N-dialkylamino group, C 1 to C 12 N-alkylsulfamoyl group or C 2 to C 12 N,N-dialkylsulfamoyl group. .

Q ^1, Q ² and Q ³ are each independently selected from ^{-CR 2 'R 3' -,} -S-, -NH-, -NR 2 '-, -CO- , or it represents a O-, R ^2' and R ^{3 '} Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J ¹ and J ² each independently represent a carbon atom or a nitrogen atom.

Y ¹ , Y ² and Y ³ each independently represent an optionally substituted aromatic hydrocarbon group or an aromatic heterocyclic group.

W ¹ and W ² each independently represent a hydrogen atom, a cyano group, a methyl group, or a halogen atom, and m represents an integer of 0-6.

Examples of the aromatic hydrocarbon group in Y ¹ , Y ² and Y ³ include aromatic hydrocarbon groups having 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group. It is preferable, and a phenyl group is more preferable. The aromatic heterocyclic group includes at least one hetero atom such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group, an oxygen atom, and a sulfur atom. An aromatic heterocyclic group is mentioned, and a furyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group are preferable.

Y ¹ , Y ² and Y ³ may each independently be substituted with a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring group. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from an aromatic ring set.

Z ⁰ , Z ¹ and Z ² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, and preferably an alkoxy group having 1 to 12 ^{carbon atoms, and Z 0} is a hydrogen atom, a carbon number 1 The alkyl group and cyano group of -12 are more preferable, and Z ¹ and Z ² are more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, and a cyano group.

Q ^1, Q ² and Q ³ is ^{-NH-, -S-, -NR 2 '-} , -O- it is preferable, and R ^2' is preferably a hydrogen atom. Among them, -S-, -O-, and -NH- are particularly preferred.

Among formulas (Ar-1) to (Ar-23), formulas (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability.

In formulas (Ar-16) to (Ar-23), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ^0. Examples of the aromatic heterocyclic group include those described above as aromatic heterocycles which may be present in Ar. For example, pyrrole ring, imidazole ring, pyrroline ring, pyridine ring, pyrazine ring, pyrimidine ring, indole ring, quinoline ring, isoquinoline Ring, purine ring, pyrrolidine ring, etc. are mentioned. This aromatic heterocyclic group may have a substituent. Further, Y ¹ may be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted as described above together with the nitrogen atom to which it is bonded and Z ^0. Examples thereof include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring.

As a compound satisfying the characteristics of the above (1) to (4), a compound in which Ar in the formula (I) is a group (II) having the following structure is also exemplified.

In formula (II), * represents L ¹ or L ² and a connection part.

D ¹ and D ² each independently represent a group selected from the following general formula (D-1).

Substituents X, X ¹ and X ² are each independently a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a pentafluorosulfanyl group, a nitro group, a cyano group, an isocyano group, an amino group, a hydroxyl group, a mercapto group, Methylamino group, dimethylamino group, diethylamino group, diisopropylamino group, trimethylsilyl group, dimethylsilyl group, thioisocyano group, or one -CH ₂ -or two or more non-adjacent -CH ₂ -are each independently- O-, -S-, -CO-, -COO-, -OCO-, -CO-S-, -S-CO-, -O-CO-O-, -CO-NH-, -NH-CO- , -CH=CH-COO-, -CH=CH-OCO-, -COO-CH=CH-, -OCO-CH=CH-, -CH=CH-, -CF=CF- or -C≡C- It represents a C1-C20 linear or branched alkyl group which may be substituted with. Any hydrogen atom in the alkyl group may be substituted with a fluorine atom.

General Formula (D-1)

In General Formula (D-1), M ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. The alkyl group may be substituted with one or more of the substituents X, or may be unsubstituted.

U ¹ represents an organic group having 2 to 30 carbon atoms having an aromatic hydrocarbon group. Any carbon atom of the aromatic hydrocarbon group may be substituted with a hetero atom. The aromatic hydrocarbon group may be substituted with one or more of the above substituents X, or may be unsubstituted.

T ¹ is -O-, -S-, -COO-, -OCO-, -OCO-O-, -NU ² -, -N=CU ² -, -CO-NU ² -, -OCO-NU ^2- Or -O-NU ² -. U ² is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, or an aromatic hydrocarbon group (even if any carbon atom of this aromatic hydrocarbon group is substituted with a hetero atom, It represents an organic group having 2 to 30 carbon atoms. The alkyl group, cycloalkyl group, cycloalkenyl group, and aromatic hydrocarbon group may each be substituted with one or more of the substituents X, or may be unsubstituted. The alkyl group may be substituted with the cycloalkyl group or the cycloalkenyl group. One of the alkyl groups -CH ₂ -or two or more non-adjacent -CH ₂ -are each independently -O-, -S-, -CO-, -COO-, -OCO-, -CO-S-, -S-CO-, -SO ₂ -, -O-CO-O-, -CO-NH-, -NH-CO-, -CH=CH-COO-, -CH=CH-OCO-, -COO- It may be substituted with CH=CH-, -OCO-CH=CH-, -CH=CH-, -CF=CF-, or -C≡C-. One of the cycloalkyl group or the cycloalkenyl group -CH ₂ -or two or more non-adjacent -CH ₂ -are each independently -O-, -CO-, -COO-, -OCO- or -O-CO- It may be substituted with O-. U ¹ and U ² may be bonded to form a ring.

In General Formula (D-1), M ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. The hydrogen atom of the alkyl group may be substituted with a fluorine atom. It is preferable that M ¹ is a hydrogen atom.

U ¹ is preferably an organic group having an aromatic heterocycle in which at least one of the carbon atoms is substituted with a hetero atom from the viewpoint of good wavelength dispersion. U ¹ is more preferably an organic group having an aromatic heterocycle which is a condensed ring of a 5-membered ring and a 6-membered ring from the viewpoint of having good wavelength dispersion and exhibiting high birefringence.

It is preferable that U ¹ has a group represented by the following formula. In addition, these groups have the number of bonds ^{with T 1 at an arbitrary position.}

T ¹ is preferably -O-, -S-, -N=CU ² -or -NU ² -from the viewpoint of good birefringence and easy synthesis. T ¹ is more preferably ^{-O-, -S- or -NU 2} -from the viewpoint of good wavelength dispersion and birefringence.

Here, U ² may be substituted with one or more of the above substituents X, and one -CH ₂ -or two or more non-adjacent -CH ₂ -s are each independently -O-, -CO-, -COO-, An alkyl group or alkenyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, or the cycloalkyl group, which may be substituted with -OCO- or -O-CO-O- , It is preferable that it is the said alkyl group or alkenyl group which may be substituted with a cycloalkenyl group or an aryl group.

Among them, U ² may be substituted with a fluorine atom in terms of birefringence and solvent solubility, and one -CH ₂ -or two or more non-adjacent -CH ₂ -s are each independently -O-, -CO-, It is more preferable that it is a C2-C20 linear alkyl group which may be substituted with -COO-, -OCO-.

U ¹ and U ² may be bonded to form a ring. In that case, for example, ^{a cyclic group represented by -NU 1} U ² or a cyclic group represented by -N=CU ¹ U ² may be mentioned.

It is particularly preferable that D ¹ and D ² each represent a group selected from the following formulas (D-1) to (D-47) in terms of easy availability of raw materials, good solubility, and high birefringence. .

The content of the polymerizable liquid crystal compound in the liquid crystal composition is usually 50 parts by mass or more and 99.5 parts by mass or less, preferably 60 parts by mass or more and 99 parts by mass or less, and more preferably 70 parts by mass, based on 100 parts by mass of the solid content of the liquid crystal composition. It is a mass part or more and 98 mass parts or less, More preferably, it is 80 mass parts or more and 97 mass parts or less. When the content ratio of the polymerizable liquid crystal is within the above range, there is a tendency for the orientation property to increase. Here, the solid content means the total amount of the components excluding the solvent in the liquid crystal composition.

The liquid crystal composition preferably contains two or more kinds of polymerizable liquid crystal compounds from the viewpoint of reducing defects caused by microcrystals in the optically anisotropic layer. When the liquid crystal composition contains two or more kinds of polymerizable liquid crystal compounds, the liquid crystal composition may contain, for example, 90% by mass or less, preferably 85% by mass or less with respect to the entire polymerizable liquid crystal compound. Includes.

From the viewpoint of improving the solubility in a solvent, the liquid crystal composition may preferably contain a dimer, a trimer, or an oligomer higher than the polymerizable liquid crystal compound together with the polymerizable liquid crystal compound. Accordingly, there is a tendency that precipitation of microcrystals is easily suppressed.

(solvent)

When the liquid crystal composition contains an organic solvent, since precipitation of crystals of the polymerizable liquid crystal compound contained in the liquid crystal composition can be suppressed, the occurrence of defects due to microcrystals in the optically anisotropic layer tends to be easily suppressed. have. In addition, when the liquid crystal composition contains an organic solvent, there is a tendency that handling and film formation at the time of forming an optical film become easy. As a solvent, it is preferable that it can completely dissolve a polymerizable liquid crystal compound, and it is preferable that it is a solvent inert to the polymerization reaction of a polymeric liquid crystal compound.

Examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether and propylene glycol monomethyl ether; Ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone or propylene glycol methyl ether acetate, and ethyl lactate; Ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone and methyl isobutyl ketone; Aliphatic hydrocarbon solvents such as pentane, hexane and heptane; Aromatic hydrocarbon solvents such as toluene and xylene, nitrile solvents such as acetonitrile; Ether solvents such as tetrahydrofuran and dimethoxyethane; Chlorine-containing solvents such as chloroform and chlorobenzene; And amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. These solvents may be used alone or in combination of two or more.

The content of the solvent is preferably 50% by mass or more and 98% by mass or less with respect to the total amount of the liquid crystal composition. In other words, the content of the solid content in the liquid crystal composition is preferably 2% by mass or more and 50% by mass or less. When the content of the solid content is 50% by mass or less, the viscosity of the liquid crystal composition is lowered, so that the thickness of the polarizing layer 12 becomes substantially uniform, so that the polarizing layer 12 tends to become less uneven. In addition, the content of the solid content may be determined in consideration of the thickness of the polarizing layer 12 to be manufactured.

(Polymerization initiator)

The liquid crystal composition may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating a polymerization reaction such as a polymerizable liquid crystal. As the polymerization initiator, from the viewpoint of not depending on the phase state of the thermotropic liquid crystal, a photopolymerization initiator that generates active radicals by the action of light is preferable.

Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts and sulfonium salts.

Examples of the benzoin compound include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

As a benzophenone compound, for example, benzophenone, o-benzoyl methylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3',4,4'-tetra(tert-butylperoxy Carbonyl)benzophenone and 2,4,6-trimethylbenzophenone, and the like.

Examples of the alkylphenone compound include diethoxyacetophenone, 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one, and 2-benzyl-2-dimethylamino-1-(4- Morpholinophenyl)butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethan-1-one, 2- Hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexylphenylketone and 2-hydroxy-2-methyl-1-[4 Oligomers of -(1-methylvinyl)phenyl]propan-1-one, and the like.

Examples of the acylphosphine oxide compound include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

As a triazine compound, for example, 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-( 4-methoxynaphthyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2, 4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6- [2-(furan-2-yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl) Ethenyl]-1,3,5-triazine and 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine And the like.

Commercially available ones can be used as polymerization initiators. As a commercially available polymerization initiator, Irgacure (registered trademark) 907, 184, 651, 819, 250 and 369, 379, 127, 754, OXE01, OXE02, OXE03 (Chiba Specialty Chemicals Co., Ltd.) Produce); Seikol (registered trademark) BZ, Z, and BEE (manufactured by Seiko Chemical Co., Ltd.); Kayacure (registered trademark) BP100 and UVI-6992 (manufactured by Dow Chemical Co., Ltd.); Adeka Optoma SP-152, N-1717, N-1919, SP-170, Adeka Arcles NCI-831, Adeka Arcles NCI-930 (manufactured by ADEKA Co., Ltd.); TAZ-A and TAZ-PP (manufactured by Nippon Siber Hegna Co., Ltd.); And TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.); And the like. One kind of polymerization initiator in the liquid crystal composition may be sufficient, and two or more kinds of a plurality of polymerization initiators may be mixed according to the light source of light.

The content of the polymerization initiator in the liquid crystal composition can be appropriately adjusted according to the type and amount of the polymerizable liquid crystal compound, but is usually 0.1 parts by mass or more and 30 parts by mass or less, preferably based on 100 parts by mass of the content of the polymerizable liquid crystal compound. It is 0.5 mass parts or more and 10 mass parts or less, More preferably, it is 0.5 mass parts or more and 8 mass parts or less. When the content of the polymerization initiator is within the above range, polymerization can be performed without disturbing the orientation of the polymerizable liquid crystal.

(Sensitizer)

The liquid crystal composition may contain a sensitizer. As a sensitizer, a photosensitizer is preferable. Examples of the sensitizer include xanthone compounds such as xanthone and thioxanthone (for example, 2,4-diethyl thioxanthone, 2-isopropyl thioxanthone, etc.); Anthracene compounds such as anthracene and alkoxy group-containing anthracene (eg, dibutoxyanthracene, etc.); Phenothiadine, rubrene, and the like.

When the liquid crystal composition contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal compound contained in the liquid crystal composition can be further accelerated. The amount of the sensitizer used is preferably 0.1 parts by mass or more and 10 parts by mass or less, more preferably 0.5 parts by mass or more and 5 parts by mass or less, and 0.5 parts by mass or more and 3 parts by mass based on 100 parts by mass of the content of the polymerizable liquid crystal compound. The following are more preferable.

(Polymerization inhibitor)

From the viewpoint of stably advancing the polymerization reaction, the liquid crystal composition may contain a polymerization inhibitor.

The degree of progression of the polymerization reaction of the polymerizable liquid crystal compound can be controlled by the polymerization inhibitor.

Examples of the polymerization inhibitor include radicals such as hydroquinone, alkoxy group-containing hydroquinone, alkoxy group-containing catechol (eg, butylcatechol), pyrogallol, and 2,2,6,6-tetramethyl-1-piperidinyloxy radical. Capture agent; Thiophenols; β-naphthylamines and β-naphthols.

When the liquid crystal composition contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.1 parts by mass or more and 10 parts by mass or less, and more preferably 0.5 parts by mass or more and 5 parts by mass based on 100 parts by mass of the content of the polymerizable liquid crystal compound. It is not more than 0.5 parts by mass, more preferably not less than 0.5 parts by mass and not more than 3 parts by mass. When the content of the polymerization inhibitor is within the above range, polymerization can be performed without disturbing the orientation of the polymerizable liquid crystal.

(Leveling agent)

The liquid crystal composition may contain a leveling agent. The leveling agent is an additive that has a function of adjusting the fluidity of the composition and making the film obtained by applying the composition more flat, such as an organic modified silicone oil-based, polyacrylate-based, and perfluoroalkyl-based leveling agent. have. Specifically, DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (above, all manufactured by Toray Dow Corning Co., Ltd.), KP321, KP323, KP324, KP326, KP340, KP341 , X22-161A, KF6001 (above, all manufactured by Shin-Etsu Chemical Co., Ltd.), TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF-4446, TSF4452, TSF4460 (above, all Momentive Performance Materials Japan) Kodo Corporation), Fluorinert (registered trademark) FC-72, copper FC-40, copper FC-43, copper FC-3283 (above, all manufactured by Sumitomo 3M), Megapak (registered trademark) R-08, East R-30, East R-90, East F-410, East F-411, East F-443, East F-445, East F-470, East F-477, East F-479, East F-482, copper F-483 (above, all manufactured by DIC Co., Ltd.), Ftop (brand name) EF301, copper EF303, copper EF351, copper EF352 (above, all manufactured by Misubishima Terial Denshi Gasei Co., Ltd.) , Saffron (registered trademark) S-381, East S-382, East S-383, East S-393, East SC-101, East SC-105, KH-40, SA-100 (above, all AGC SEMI Chemical Co., Ltd.), brand name E1830, copper E5844 (manufactured by Daikin Fine Chemical Co., Ltd.), BM-1000, BM-1100, BYK-352, BYK-353 and BYK-361N (all brand names: BM Chemie Manufactured by Co., Ltd.), etc. are mentioned. Among them, a polyacrylate-based leveling agent and a perfluoroalkyl-based leveling agent are preferable.

When the liquid crystal composition contains a leveling agent, based on 100 parts by mass of the content of the polymerizable liquid crystal compound, preferably 0.01 parts by mass or more and 5 parts by mass or less, more preferably 0.1 parts by mass or more and 5 parts by mass or less, even more preferably Is 0.1 parts by mass or more and 3 parts by mass or less. When the content of the leveling agent is within the above range, it is easy to horizontally align the polymerizable liquid crystal compound, and the obtained polarizing film tends to become smoother. When the content of the leveling agent in the polymerizable liquid crystal compound exceeds the above range, there is a tendency that unevenness tends to occur in the obtained polarizing film. Moreover, the liquid crystal composition may contain 2 or more types of leveling agents.

Further, by appropriately adjusting the coating amount and concentration of the liquid crystal composition, the film thickness can be adjusted so as to impart a desired retardation. In the case of a liquid crystal composition in which the amount of the polymerizable liquid crystal compound is constant, the retardation value (retardation value, Re(λ)) of the obtained retardation film is determined as shown in the following formula (a). You may adjust the thickness d.

Re(λ)=d×Δn(λ) (a)

[In the formula, Re(λ) represents the retardation value at the wavelength λ nm, d represents the film thickness, and Δn(λ) represents the birefringence index at the wavelength λ nm]

(Application of liquid crystal composition)

As a method of applying the liquid crystal composition onto a substrate or alignment film, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a CAP coating method, a slit coating method, a microgravure method, a die coating method, an ink jet method, and the like can be mentioned. . Further, a method of coating using a coater such as a dip coater, a bar coater, and a spin coater may be mentioned. Among them, in the case of continuous coating in a roll-to-roll format, a microgravure method, an inkjet method, a slit coating method, or a die coating method is preferable. When the substrate is a single-leaf type, a spin coating method with high uniformity is preferred. desirable. In the case of applying in a roll-to-roll format, a composition for forming a photo-alignment film or the like for forming an alignment film may be applied to a substrate to form an alignment film, and a liquid crystal composition may be continuously applied on the obtained alignment film.

The substrate to which the liquid crystal composition is applied tends to reduce the number of specific defects caused by microcrystals by keeping it warm at a constant temperature when the liquid crystal composition is applied. The temperature to keep warm may be, for example, 20°C or more and 60°C or less, and preferably 30°C or more and 50°C or less.

From the viewpoint of increasing the uniformity of the coating film of the polymerizable liquid crystal compound, and reducing the number of specific defects caused by spatter of the coating film of the polymerizable liquid crystal compound or poor alignment film, the smoothness of the surface of the substrate can be improved by annealing (surface cleaning). . The annealing temperature may be, for example, 60°C or more and 100°C or less, or 5°C or more and 20°C or less lower than the glass transition point of the substrate, and the time may be 1 second or more and 60 seconds or less.

By making the humidity of the surrounding atmosphere constant during coating, it becomes easy to suppress crystallization of the polymerizable liquid crystal compound, and the number of specific defects caused by microcrystals tends to decrease. The humidity of the ambient atmosphere may be, for example, 90%RH or less, preferably 85%RH or less, more preferably 60%RH or less, still more preferably 55%RH or less, and particularly preferably 40%RH or less. . On the other hand, the humidity of the surrounding atmosphere during coating may be, for example, 10%RH or more, and preferably 20%RH or more. In the case of using a polymerizable liquid crystal compound having a relatively large molecular weight, in order to make the number of specific defects within the range specified in the present invention, the humidity when the polymerizable liquid crystal compound is applied onto a substrate can be relatively lowered.

By adjusting the atmosphere around the die used for coating by the vapor pressure of the solvent contained in the polymerizable liquid crystal compound (under the solvent atmosphere), the solvent of the polymerizable liquid crystal compound becomes difficult to volatilize, and crystallization of the polymerizable liquid crystal compound is suppressed, and microcrystalline The number of specific defects caused by the tends to be small.

From the viewpoint of reducing the number of specific defects caused by foreign matter, the substrate is preferably cleaned before application of the liquid crystal composition to remove surface contamination such as PET lubricant, PET oligomer, silicone oil, and the like.

In order to remove foreign matters, microcrystals, and the like in the liquid crystal composition to be coated, filtering can be performed before coating, preferably immediately before coating. Further, by applying the liquid crystal composition in a clean room, the number of specific defects caused by foreign matter can be reduced.

(Drying of liquid crystal composition)

Examples of the drying method for removing the solvent contained in the liquid crystal composition include natural drying, air drying, heat drying, vacuum drying, and a combination thereof. Among them, natural drying or heat drying is preferable. The drying temperature may be, for example, 0°C or more and 200°C or less, more preferably 20°C or more and 150°C or less, and still more preferably 50°C or more and 130°C or less. The drying time may be, for example, 10 seconds or more and 10 minutes or less, and preferably 30 seconds or more and 5 minutes or less. Orienting polymer composition can also be dried in the same way.

(Polymerization of polymerizable liquid crystal compound)

Photopolymerization is preferable as a method of polymerizing the polymerizable liquid crystal compound. Photopolymerization is carried out by irradiating an active energy ray to a laminate to which a liquid crystal composition is applied with a polymerizable liquid crystal compound on a substrate or an alignment film. As the active energy ray to be irradiated, depending on the kind of the polymerizable liquid crystal compound contained in the dry film (especially the kind of the photopolymerizable functional group of the polymerizable liquid crystal compound), and in the case of containing a photopolymerization initiator, the type of the photopolymerization initiator and the amount thereof. It is selected appropriately. Specifically, at least one type of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-ray, α-ray, β-ray, and γ-ray can be mentioned. Among them, since it is easy to control the progress of the polymerization reaction, and that what is widely used in the art as a photopolymerization device can be used, ultraviolet light is preferable, and a polymerizable liquid crystal compound so that photopolymerization is possible by ultraviolet light. It is desirable to choose the type of.

As the light source of the active energy ray, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, a wavelength range of 380 nm or more to 440 nm. LED light sources emitting the following light, chemical lamps, black light lamps, microwave excitation mercury lamps, metal halide lamps, and the like.

The ultraviolet irradiation intensity is usually 10 mW/cm 2 or more and 3,000 mW/cm 2 or less.

The ultraviolet irradiation intensity is preferably the intensity in a wavelength range effective for activation of a cationic polymerization initiator or a radical polymerization initiator. The time to irradiate light is usually 0.1 second or more and 10 minutes or less, preferably 0.1 second or more and 5 minutes or less, more preferably 0.1 second or more and 3 minutes or less, and still more preferably 0.1 second or more and 1 minute or less. When irradiated once or multiple times with such ultraviolet irradiation intensity, the accumulated light amount is 10 mJ/cm 2 or more and 3,000 mJ/cm 2 or less, preferably 50 mJ/cm 2 or more and 2,000 mJ/cm 2 or less, more preferably 100 mJ/cm 2 It is more than 1,000 mJ/cm<2> or less. When the cumulative amount of light is within this range, curing of the polymerizable liquid crystal compound becomes sufficient, and good transferability tends to be easily obtained, and coloration of the optical laminate tends to be easily suppressed.

1 is a schematic diagram showing an embodiment of an optical film according to an aspect of the present invention. The optical film 10 has an optically anisotropic layer 11, an alignment layer 12, and a base layer 13 in this order.

[Phase difference laminate]

The retardation laminate includes one or more of the above-described optical films. The retardation layered product may have one or more retardation layers, and may be, for example, a film used to convert linearly polarized light into circularly polarized light or elliptically polarized light, or conversely, from circularly polarized light or elliptically polarized light into linearly polarized light.

When the retardation laminate has a first retardation layer and a second retardation layer, the retardation laminate can be attached to a polarizing plate and used as a circular polarizing plate. When used as a circular polarizing plate, the first retardation layer may be used as a quarter-wavelength retardation layer having reverse wavelength dispersion, and the second retardation layer may be used as a positive C plate, or the first retardation layer may be used as a half-wavelength retardation layer. In addition, the second retardation layer may be a 1/4 wavelength retardation layer.

The phase difference layered product will be described with reference to the drawings.

2 is a schematic diagram showing an embodiment of a phase difference laminate. The retardation laminate 20 includes a first base layer 31, a first alignment layer 32, a first retardation layer 33, an adhesive layer 34, a second retardation layer 35, and a second alignment layer 36. ) And the second base layer 37 in this order.

The first laminate 21 composed of the first base layer 31, the first alignment layer 32 and the first retardation layer 33 may be composed of the optical film 10 of the present invention described above.

The second laminate 22 composed of the second retardation layer 35, the second alignment layer 36, and the second base layer 37 may be composed of the optical film 10 of the present invention described above.

The adhesive layer 34 may be formed of an adhesive, an adhesive, or a combination thereof.

The adhesive layer 34 is usually one layer, but may be two or more layers. The adhesive layer 34 may be formed by applying the adhesive composition to the bonding surface of the base layer or the retardation layer. As the coating method, a conventional coating technique using a die coater, a comma coater, a reverse roll coater, a gravure coater, a rod coater, a wire bar coater, a doctor blade coater, an air doctor coater, or the like may be employed.

As the adhesive, a (meth)acrylic adhesive, a styrene adhesive, a silicone adhesive, a rubber adhesive, a urethane adhesive, a polyester adhesive, an epoxy copolymer adhesive, or the like can be used.

As the adhesive, for example, it can be formed by combining one or two or more of a water-based adhesive, an active energy ray-curable adhesive, and an adhesive. Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution, an aqueous two-component urethane emulsion adhesive, and the like. As an active energy ray-curable adhesive, it is an adhesive that cures by irradiating an active energy ray such as ultraviolet rays, and includes, for example, a polymerizable compound and a photopolymerization initiator, a photoreactive resin, a binder resin and a photoreactive crosslinking agent. And things to do. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and oligomers derived from these monomers. Examples of the photopolymerization initiator include those containing substances that generate active species such as neutral radicals, anionic radicals, and cationic radicals by irradiation with active energy rays such as ultraviolet rays.

The thickness of the adhesive layer 34 may be, for example, 0.1 µm or more and 25 µm or less, preferably 0.5 µm or more and 20 µm or less, more preferably 1 µm or more and 15 µm or less, even more preferably 2 µm or more and 10 µm or less, particularly It is preferably 2.5 µm or more and 5 µm or less.

The retardation laminate 20 is, for example, a step of preparing the first laminate 21 and the second retardation layer 22, and an adhesive layer on the surface of the first laminate 21 on the first retardation layer 33 side. It can be manufactured by a manufacturing method including a step of forming (34) and a step of attaching the first layered body 21 and the second phase difference layer 22 to each of the phase difference layer surfaces as a bonding surface.

[Polarizer]

By combining the above-described retardation laminate and a polarizer, a polarizing plate such as an elliptically polarizing plate and a circular polarizing plate are provided.

Since the polarizing plate of the present invention has an optically anisotropic layer with improved film strength and workability, cracks and the like tend to be less likely to occur even when cut. Therefore, the polarizing plate of the present invention is suitable for a polarizing plate having a cut surface or a release polarizing plate. The release polarizing plate may be, for example, a polarizing plate having a planar shape other than a rectangular shape and a square shape, or a polarizing plate having a through hole in a planar region from the outermost periphery to the inner side. The polarizing plate may be a long or single-leaf type.

3 is a schematic diagram showing an embodiment of a polarizing plate. The polarizing plate 40 includes a polarizer 39, an adhesive layer 38, a first alignment layer 32, a first retardation layer 33, an adhesive layer 34, a second retardation layer 35, and a second alignment layer ( 36) and the second base layer 37 are provided in this order.

Any suitable polarizer may be employed as the polarizer 39. The polarizer refers to a linear polarizer having a property of transmitting linearly polarized light having a vibrating surface orthogonal to an absorption axis when unpolarized light is incident. For example, the resin film forming the polarizer may be a single-layered resin film or a laminated film of two or more layers. The polarizer 39 may be a cured film obtained by aligning a dichroic dye to a polymerizable liquid crystal compound and polymerizing the polymerizable liquid crystal compound.

As a specific example of a polarizer composed of a single-layer resin film, such as a polyvinyl alcohol (hereinafter sometimes abbreviated as "PVA")-based film, a partially formalized PVA-based film, an ethylene/vinyl acetate copolymer-based partial saponification film, and the like The hydrophilic polymer film is dyed and stretched with a dichroic substance such as iodine or a dichroic dye, and polyene-based oriented films such as PVA dehydration treatment and polyvinyl chloride dehydrochloric acid treatment. I can. Since the optical properties are excellent, it is preferable to use a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching it.

Polyvinyl alcohol-based resin can be produced by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and other monomers copolymerizable with vinyl acetate in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is usually 85 mol% or more and 100 mol% or less, and preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 or more and 10,000 or less, and preferably 1,500 or more and 5,000 or less.

What formed such a polyvinyl alcohol-based resin into a film is used as a raw film of a polarizer. The method of forming a film of the polyvinyl alcohol-based resin is not particularly limited, and may be formed by a known method. The film thickness of the polyvinyl alcohol-based resin original film is, for example, 10 µm or more and 100 µm or less, preferably 10 µm or more and 60 µm or less, and more preferably 15 µm or more and 30 µm or less.

As another method of manufacturing the polarizer 39, first, a base film is prepared, a resin solution such as polyvinyl alcohol-based resin is applied on the base film, and drying to remove the solvent is performed to form a resin layer on the base film. What includes the step of forming is mentioned. In addition, a primer layer may be formed in advance on the surface of the base film on which the resin layer is formed. As the base film, a resin film such as PET can be used. As the material of the primer layer, a resin obtained by crosslinking a hydrophilic resin used for a polarizer may be mentioned.

Then, if necessary, the amount of solvent such as moisture in the resin layer is adjusted, and then, the base film and the resin layer are uniaxially stretched, and then the resin layer is dyed with a dichroic dye such as iodine, and the dichroic dye is applied to the resin layer. Adsorption orientation. Next, if necessary, the resin layer in which the dichroic dye is adsorbed and oriented is treated with an aqueous boric acid solution to wash the aqueous boric acid solution. Accordingly, a resin layer in which a dichroic dye is adsorbed and oriented, that is, a film of a polarizer is produced. A known method can be employed for each process.

The uniaxial stretching of the base film and the resin layer may be performed before dyeing, during dyeing, during boric acid treatment after dyeing, or uniaxial stretching may be performed in a plurality of these steps. The base film and the resin layer may be uniaxially stretched in the MD direction (film conveyance direction), and in this case, it may be stretched uniaxially between rolls having different circumferential speeds, or uniaxially stretched using a hot roll. In addition, the base film and the resin layer may be uniaxially stretched in the TD direction (direction perpendicular to the film conveyance direction), and in this case, a so-called tenter method can be used. Further, the stretching of the base film and the resin layer may be dry stretching performed in the air, or wet stretching performed in a state in which the resin layer is swollen with a solvent. In order to express the performance of the polarizer, the draw ratio is 4 times or more, preferably 5 times or more, and particularly preferably 5.5 times or more. There is no particular upper limit of the draw ratio, but it is preferably 8 times or less from the viewpoint of suppressing breakage and the like.

The polarizer 39 produced by the above method can be obtained by laminating a protective layer to be described later and then peeling the base film. According to this method, further thinning of the polarizer becomes possible.

As a method for producing a polarizer 39, which is a cured film obtained by aligning a dichroic dye in a polymerizable liquid crystal compound and polymerizing a polymerizable liquid crystal compound, for forming a polarizer comprising a polymerizable liquid crystal compound and a dichroic dye on a base film. A method of forming a polarizer by applying the composition and polymerizing and curing the polymerizable liquid crystal compound while maintaining the liquid crystal state is exemplified. The polarizer thus obtained is in a state of being laminated on the base film, and may be used as a polarizer with a base film. Alternatively, after laminating a polarizer with a base film through an adhesive layer on a retardation layered product, or after laminating on an adhesive layer with a release layer, the base film may be peeled and used.

As the dichroic dye, a dye having a property different in absorbance in the long axis direction and absorbance in the short axis direction of the molecule can be used, for example, a dye having a maximum absorption wavelength (λmax) in the range of 300 nm to 700 nm. Is preferred. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes. Among them, azo dyes are preferred. Examples of the azo dye include a monoazo dye, a bis azo dye, a tris azo dye, a tetrakis azo dye, and a stilbenazo dye, and a bis azo dye and a tris azo dye are more preferable.

The composition for forming a polarizer may contain a solvent, a polymerization initiator such as a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, and the like. As for the polymerizable liquid crystal compound, dichroic dye, solvent, polymerization initiator, photosensitizer, polymerization inhibitor, etc. contained in the composition for forming a polarizer, known ones can be used. For example, Japanese Patent Laid-Open No. 2017-102479, Japan What is illustrated in Patent Publication No. 2017-83843 can be used. In addition, the polymerizable liquid crystal compound may be the same as the compound exemplified as the polymerizable liquid crystal compound used to obtain the above-described optically anisotropic layer.

As for the method of forming a polarizer using the composition for forming a polarizer, the method exemplified in the above publication can be employed.

The thickness of the polarizer 39 may be, for example, 2 µm or more, and preferably 3 µm or more.

On the other hand, the thickness of the polarizer 39 is, for example, 25 µm or less, and preferably 15 µm or less. In addition, the above-described upper limit and lower limit can be arbitrarily combined. As the thickness of the polarizer 39 decreases, the stiffness decreases, and there is a tendency to be easily affected by the shrinkage stress of the optically anisotropic layer described above.

The polarizer 39 may stack a protective layer on one or both sides thereof through a known adhesive layer or an adhesive layer. As the protective layer that can be laminated on one or both sides of the polarizer 39, a film formed of a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, stretchability, and the like is used. Specific examples of such a thermoplastic resin include cellulose resins such as triacetyl cellulose; Polyester resins such as polyethylene terephthalate and polyethylene naphthalate; Polyethersulfone resin; Polysulfone resin; Polycarbonate resin; Polyamide resins such as nylon and aromatic polyamide; Polyimide resin; Polyolefin resins such as polyethylene, polypropylene, and ethylene/propylene copolymer; Cyclic polyolefin resin having a cyclo-based and norbornene structure (also referred to as a norbornene-based resin); (Meth)acrylic resin; Polyarylate resin; Polystyrene resin; And polyvinyl alcohol resins and mixtures thereof. When protective layers are laminated on both surfaces of the polarizer 39, the resin composition of the two protective layers may be the same or different. In this specification, "(meth)acryl" means that either acrylic or methacrylic may be used. "(Meth)" such as (meth)acrylate has the same meaning.

A film formed of a thermoplastic resin may be subjected to surface treatment (for example, corona treatment, etc.) in order to improve adhesion to a polarizer containing a PVA-based resin and a dichroic substance, and a primer layer (also referred to as an undercoat layer) or the like. A thin layer of may be formed.

The protective layer may be, for example, stretched or non-stretched thermoplastic resin (hereinafter, sometimes referred to as "unstretched resin"). Examples of the stretching treatment include uniaxial stretching and biaxial stretching.

The thickness of the protective layer may be, for example, 3 µm or more, and preferably 5 µm or more. On the other hand, the thickness of the protective layer may be, for example, 50 µm or less, and preferably 30 µm or less.

In addition, the above-described upper limit and lower limit can be arbitrarily combined.

The surface of the protective layer opposite to the polarizer may have a surface treatment layer, for example, a hard coat layer, an antireflection layer, an anti-sticking layer, an anti-glare layer, a diffusion layer, and the like. The surface treatment layer may be a separate layer laminated on the protective layer, or may be formed by performing a surface treatment on the surface of the protective layer.

The hard coat layer is for the purpose of preventing scratches on the surface of the polarizing plate, and can be formed by, for example, adding a cured film having excellent hardness and sliding properties with an ultraviolet curable resin such as acrylic or silicone to the surface of the protective layer. I can. The antireflection layer is for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming a conventional antireflection film or the like. In addition, the anti-sticking layer is for the purpose of preventing adhesion with adjacent layers.

The anti-glare layer is intended to prevent external light from being reflected from the surface of the polarizing plate and impeding the visibility of the transmitted light of the polarizing plate, for example, a roughening method or a transparent method by a sand blast method or an embossing method. It can be formed by imparting a fine uneven structure to the surface of the protective layer by a method such as a blending method of fine particles. As transparent fine particles used to impart a fine uneven structure to the surface of the protective layer, for example, silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle diameter of 0.5 µm or more and 50 µm or less are conductive. And fine particles such as inorganic fine particles and organic fine particles such as a crosslinked or uncrosslinked polymer. The content of the transparent fine particles is generally 2 parts by mass or more and 50 parts by mass or less, and preferably 5 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the resin forming the layer forming the fine uneven structure. The anti-glare layer may also serve as a diffusion layer (a vision magnifying function, etc.) for diffusing the transmitted light of the polarizing plate to enlarge the vision and the like.

When the surface treatment layer is a separate layer laminated on the protective layer of the polarizing plate, the thickness of the surface treatment layer may be, for example, 0.5 µm or more, and preferably 1 µm or more. On the other hand, the thickness of the surface treatment layer may be, for example, 10 µm or less, and preferably 8 µm or less. When the thickness is within the above range, it is easy to effectively prevent scratches on the surface of the polarizing plate, curing shrinkage is suppressed, and the reverse curl of the polarizing plate tends to be easily suppressed.

The adhesive layer 38 may be composed of an adhesive. As the pressure-sensitive adhesive, a conventionally known pressure-sensitive adhesive having excellent optical transparency can be used without particular limitation, and for example, a pressure-sensitive adhesive having a base polymer such as acrylic, urethane, silicone, and polyvinyl ether may be used. Moreover, an active energy ray-curable adhesive, a thermosetting adhesive, etc. may be sufficient. Among these, a pressure-sensitive adhesive made of an acrylic resin excellent in transparency, adhesion, re-peelability, weather resistance, heat resistance, etc. as a base polymer is suitable. It is preferable that the adhesive layer is comprised of the reaction product of the adhesive composition containing a (meth)acrylic resin, a crosslinking agent, and a silane compound.

In the pressure-sensitive adhesive composition, an ultraviolet-curable compound such as a multifunctional acrylate is mixed to form an active energy ray-curable pressure-sensitive adhesive, and after forming the pressure-sensitive adhesive layer of the active energy-ray-curable pressure-sensitive adhesive, it is cured by irradiation with ultraviolet rays to obtain a harder pressure-sensitive adhesive layer. useful. The active energy ray-curable pressure-sensitive adhesive has a property of curing by being irradiated with energy rays such as ultraviolet rays or electron beams.

Since the active energy ray-curable adhesive has adhesiveness even before irradiation with energy rays, it adheres to an adherend such as an optical film or a liquid crystal layer, and is cured by irradiation with energy rays to adjust the adhesive force.

The active energy ray-curable adhesive generally contains an acrylic adhesive and an energy ray polymerizable compound as main components. Usually, a crosslinking agent is further blended, and a photoinitiator, a photosensitizer, or the like can also be blended if necessary.

The thickness of the adhesive layer 38 may be, for example, 3 µm or more and 40 µm or less, and preferably 3 µm or more and 30 µm or less.

[Flexible image display device]

The flexible image display device includes a laminate for a flexible image display device and an organic EL display panel, and a laminate for a flexible image display device is disposed on the viewer side with respect to the organic EL display panel so that it can be folded and bent. Being able to fold and bend means that it can be bent without causing cracks and fractures. As the laminate for a flexible image display device, a polarizing plate provided with at least one of a front plate or a touch sensor may be used. When the polarizing plate has both the front plate and the touch sensor, the order of stacking them is arbitrary, but the front plate, the polarizing plate, and the touch sensor are stacked from the viewer side in the order of the front plate, the touch sensor, and the polarizing plate from the viewer side. It is desirable to have. The presence of a polarizing plate on the visible side of the touch sensor is preferable because the pattern of the touch sensor becomes difficult to be visually recognized and the visibility of the displayed image is improved. Each member may be laminated using an adhesive or an adhesive. In addition, a light shielding pattern formed on at least one surface of any one layer of the front plate, the polarizing plate, and the touch sensor may be provided. Each layer (a front plate, a polarizing plate, a touch sensor) forming a laminate for a flexible image display device and a film member (a linear polarizing plate, a quarter-wavelength retardation plate, etc.) constituting each layer can be formed by an adhesive. The polarizing plate is a polarizing plate containing the optical film or retardation laminate of the present invention, and preferably a circular polarizing plate. Further, the polarizing plate may be a polarizing plate having a cut surface or a deformed polarizing plate.

(Front panel)

The front plate is preferably a plate-like body capable of transmitting light. The front plate may be composed of only one layer, or may be composed of two or more layers. The front plate may not only have a function (window) for protecting the front surface (screen) of the image display device, but may also have a function as a touch sensor, a blue light cut function, a viewing angle adjustment function, and the like. The front plate is preferably a window.

(window)

The window, for example, is disposed on the viewer's side of the flexible image display device to be described later, and serves to protect other components from external impacts or environmental changes such as temperature and humidity.

Conventionally, glass has been used as such a protective layer, but a window in a flexible image display device described later is not as hard and hard as glass, but has a flexible characteristic. The window includes a flexible transparent substrate, and may include a hard coat layer on at least one surface.

(Transparent description)

The transparent substrate has a visible light transmittance of 70% or more, preferably 80% or more. Any transparent substrate may be used as long as it is a transparent polymer film. Specifically, polyolefins such as polyethylene, polypropylene, polymethylpentene, norbornene or cycloolefin derivatives having a monomeric unit containing a cycloolefin, diacetyl cellulose, triacetyl cellulose, propionyl cellulose, etc. Modified) Cellulose, acrylics such as methyl methacrylate (co)polymers, polystyrenes such as styrene (co)polymers, acrylonitrile/butadiene/styrene copolymers, acrylonitrile/styrene copolymers, ethylene-vinyl acetate Copolymers, polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyesters such as polyarylate, polyamides such as nylon, polyimides, Films made of polymers such as polyamide imides, polyether imides, polyether sulfones, polysulfones, polyvinyl alcohol, polyvinyl acetals, polyurethanes, and epoxy resins may be used, and unstretched uniaxial or biaxial A stretched film can be used. These polymers may be used alone or in combination of two or more. Preferably, among the above transparent substrates, a polyamide film, polyamide-imide film or polyimide film, a polyester film, an olefin film, an acrylic film, and a cellulose film having excellent transparency and heat resistance are preferred. It is also preferable to disperse inorganic particles such as silica, organic fine particles, and rubber particles in the polymer film. In addition, a coloring agent such as a pigment or dye, a fluorescent whitening agent, a dispersing agent, a plasticizer, a heat stabilizer, a light stabilizer, an infrared absorber, an ultraviolet absorber, an antistatic agent, an antioxidant, a lubricant, a solvent, and the like may be contained. The thickness of the transparent substrate is 5 µm or more and 200 µm or less, and preferably 20 µm or more and 100 µm or less.

(Hard coat)

The window may have a hard coat layer formed on at least one surface of the transparent substrate.

The thickness of the hard coat layer is not particularly limited, and may be, for example, 2 µm or more and 100 µm or less. When the thickness of the hard coat layer is less than 2 µm, it is difficult to ensure sufficient scratch resistance, and when it exceeds 100 µm, the bending resistance decreases, and a problem of curling due to cure shrinkage may occur.

The hard coat layer can be formed by curing a hard coat composition containing a reactive material that forms a crosslinked structure by irradiating with active energy rays or thermal energy, but is preferably cured with active energy rays. An active energy ray is defined as an energy ray capable of generating an active species by decomposing a compound that generates an active species. Examples of active energy rays include visible light, ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays, and electron rays. Ultraviolet rays are particularly preferred. The hard coat composition contains at least one polymer of a radical polymerizable compound and a cationic polymerizable compound.

The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group that the radical polymerizable compound has may be a functional group capable of causing a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond. Specifically, a vinyl group, a (meth)acryloyl group, etc. are mentioned. Further, when the radically polymerizable compound has two or more radically polymerizable groups, these radically polymerizable groups may be the same or different, respectively. The number of radically polymerizable groups in one molecule of the radical polymerizable compound is preferably two or more from the viewpoint of improving the hardness of the hard coat layer. As the radical polymerizable compound, a compound having a (meth)acryloyl group is particularly preferable from the viewpoint of high reactivity, and is called a polyfunctional acrylate monomer having 2 to 6 (meth)acryloyl groups in one molecule. Compounds or oligomers having several (meth)acryloyl groups in a molecule called epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate can be preferably used. . It is preferable to include at least one selected from epoxy (meth) acrylate, urethane (meth) acrylate and polyester (meth) acrylate.

The cationic polymerizable compound is a compound having a cationic polymerizable group such as an epoxy group, an oxetanyl group, and a vinyl ether group. The number of cationic polymerizable groups in one molecule of the cationic polymerizable compound is preferably two or more, and more preferably three or more from the viewpoint of improving the hardness of the hard coat layer. Moreover, as a cationic polymerizable compound, the compound which has at least 1 type of an epoxy group and an oxetanyl group as a cationic polymerizable group is especially preferable. Cyclic ether groups, such as an epoxy group and an oxetanyl group, are preferable in that the shrinkage accompanying the polymerization reaction is small. Further, the compound having an epoxy group among the cyclic ether groups has the advantage that it is easy to obtain compounds of various structures, does not adversely affect the durability of the obtained hard coat layer, and is easy to control compatibility with the radical polymerizable compound. In addition, the oxetanyl group among the cyclic ether groups tends to have a higher degree of polymerization compared to the epoxy group, has low toxicity, and accelerates the rate of network formation obtained from the cationic polymerizable compound of the obtained hard coat layer, even in a region mixed with the radical polymerizable compound. There is an advantage of forming an independent network without leaving unreacted monomers in the film.

As a cationic polymerizable compound having an epoxy group, for example, an alicyclic epoxy obtained by epoxidating a polyglycidyl ether of a polyhydric alcohol having an alicyclic ring or a cyclohexene ring or a cyclopentene ring-containing compound with a suitable oxidizing agent such as hydrogen peroxide or peracid. Suzy; Aliphatic epoxy resins such as polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, polyglycidyl esters of aliphatic long-chain polybasic acids, homopolymers of glycidyl (meth)acrylates, and copolymers; Glycidyl ether and novolac prepared by reaction of bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A, or derivatives such as alkylene oxide adducts and caprolactone adducts, and epichlorohydrin It is an epoxy resin and the like, and a glycidyl ether type epoxy resin derived from bisphenols, etc. are mentioned.

The hard coat composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, a radical and a cationic polymerization initiator, and the like, and can be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating, and generate radicals or cations to advance radical polymerization and cationic polymerization.

The radical polymerization initiator may release a substance that initiates radical polymerization by at least one of irradiation with active energy rays and heating. Examples of the thermal radical polymerization initiator include organic peroxides such as hydrogen peroxide and hyperbenzoic acid, and azo compounds such as azobisbutyronitrile.

As the active energy ray radical polymerization initiator, there are a type 1 type radical polymerization initiator in which radicals are generated by decomposition of molecules, and a type 2 type radical polymerization initiator in which radicals are generated by hydrogen extraction reaction in coexistence with a tertiary amine. It can also be used in combination or in combination.

The cationic polymerization initiator may release a substance that initiates cationic polymerization by at least one of irradiation with active energy rays and heating. As a cationic polymerization initiator, an aromatic iodonium salt, an aromatic sulfonium salt, a cyclopentadienyl iron (II) complex, etc. can be used. These can initiate cationic polymerization by either or all of irradiation with active energy rays or heating due to the difference in structure.

The polymerization initiator may contain 0.1 to 10% by weight based on 100% by weight of the total hard coat composition. If the content of the polymerization initiator is less than 0.1% by weight, curing cannot be sufficiently advanced, and it is difficult to implement the mechanical properties or adhesion of the finally obtained coating film.If it exceeds 10% by weight, poor adhesion or cracking due to curing shrinkage And a curl phenomenon may occur.

The hard coat composition may further include one or more selected from the group consisting of a solvent and an additive. The solvent is one capable of dissolving or dispersing a polymerizable compound and a polymerization initiator, and any solvent known as a solvent for a hard coat composition in the art may be used without limitation. The additive may further include inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, and the like.

(Circular polarizer)

The circular polarizing plate is a functional layer having a function of transmitting only right or left circularly polarized components by laminating a quarter-wavelength retardation layer (hereinafter, also referred to as a λ/4 retardation layer) on a linear polarizing plate. For example, it is used for converting external light into right circular polarized light, blocking external light reflected from the organic EL panel to become left circularly polarized light, and transmitting only the light emitting component of the organic EL, thereby suppressing the influence of the reflected light and making the image easier to see. In order to achieve the circular polarization function, the absorption axis of the linear polarizer or the linear polarizing plate and the slow axis of the λ/4 retardation layer need to be 45° in theory, but are practically 45±10°. The linear polarizer or the linear polarizing plate and the λ/4 retardation layer do not necessarily need to be laminated adjacent to each other, and the relationship between the absorption axis and the slow axis may satisfy the above-described range. It is desirable to achieve complete circular polarization at all wavelengths, but in practical use, since it is not necessarily necessary, the circular polarizing plate in the present invention also includes an elliptically polarizing plate. It is also preferable to laminate a λ/4 retardation film on the viewing side of a linear polarizer or a linear polarizing plate to make the outgoing light circularly polarized, thereby improving visibility in a state of wearing polarized sunglasses.

The linear polarizing plate is a functional layer having a function of allowing light vibrating in a transmission axis direction to pass, but blocking polarization of a vibration component perpendicular thereto. The linear polarizing plate may be constituted with a linear polarizer alone or a linear polarizer and a protective film adhered to at least one surface thereof. The thickness of the linear polarizing plate may be 200 µm or less, and preferably 0.5 µm or more and 100 µm or less. When the thickness exceeds 200 µm, the flexibility may decrease.

The linear polarizer may be a film-type polarizer manufactured by dyeing and stretching a polyvinyl alcohol (PVA)-based film. A dichroic dye is oriented to the PVA-based film oriented by stretching, or a dichroic dye such as iodine is adsorbed or stretched in a state adsorbed by PVA, whereby the dichroic dye is oriented to exhibit polarization performance. In the production of a film-type polarizer, other steps such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying may be provided. The stretching or dyeing process may be performed by the PVA-based film alone, or may be performed in a state of being laminated with another film such as polyethylene terephthalate. As the PVA-based film to be used, 10 µm or more and 100 µm or less, and the draw ratio are preferably 2 to 10 times.

Further, as another example of the linear polarizer, a liquid crystal coating type polarizer formed by applying a liquid crystal polarizing composition may be used. The liquid crystal polarizing composition may include a liquid crystal compound and a dichroic dye compound. As a liquid crystal compound, what is necessary is just to have a property which shows a liquid-crystal state, and especially what has a high order alignment state, such as a smectic phase, can exhibit high polarization performance, and is preferable. Moreover, it is also preferable to have a polymerizable functional group. The dichroic dye compound is a dye that is oriented together with a liquid crystal compound to exhibit dichroism, and the dichroic dye itself may have liquid crystal properties or may have a polymerizable functional group. Any one compound in the liquid crystal polarizing composition has a polymerizable functional group. The liquid crystal polarizing composition may further contain an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal polarizing layer can be produced by applying a liquid crystal polarizing composition on the alignment film to form a liquid crystal polarizing layer. The liquid crystal polarizing layer may have a thinner thickness compared to the film-type polarizer. The thickness of the liquid crystal polarizing layer may be 0.5 µm or more and 10 µm or less, preferably 1 µm or more and 5 µm or less.

The alignment film can be produced, for example, by applying an alignment film-forming composition on a substrate and imparting alignment by rubbing, polarized light irradiation, or the like. In addition to the alignment agent, the alignment film forming composition may contain a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like.

As the aligning agent, for example, polyvinyl alcohol, polyacrylates, polyamic acids, and polyimides can be used. When applying photo-alignment, it is preferable to use an alignment agent containing a cinnamate group. The polymer used as the aligning agent may have a weight average molecular weight of about 10,000 to 100,000. The alignment film is preferably 5 nm or more and 10,000 nm or less, and particularly preferably 10 nm or more and 500 nm or less because the orientation regulating force is sufficiently expressed. The liquid crystal polarizing layer may be peeled off from the substrate and transferred to be laminated, or the substrate may be laminated as it is. It is also preferable that the substrate serves as a protective film, a retardation plate, or a transparent substrate for a window.

As the protective film, a transparent polymer film may be used, and materials and additives used for the transparent substrate can be used. A cellulose film, an olefin film, an acrylic film, and a polyester film are preferable. A coating-type protective film obtained by applying and curing a cationic curing composition such as an epoxy resin or a radical curing composition such as an acrylate may be used. Plasticizers, ultraviolet absorbers, infrared absorbers, colorants such as pigments and dyes, fluorescent whitening agents, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, solvents, etc. may be included as needed. The thickness of the protective film may be 200 µm or less, and preferably 1 µm or more and 100 µm or less. When the thickness exceeds 200 µm, the flexibility may decrease. It can also serve as a transparent substrate for the window.

The λ/4 retardation layer may be the optical film of the present invention, or may be a film that imparts a phase difference of λ/4 in a direction orthogonal to the advancing direction of the incident light (in-plane direction of the film). The film which imparts a retardation of λ/4 may be a stretched retardation plate manufactured by stretching a polymer film such as a cellulose film, an olefin film, or a polycarbonate film. If necessary, a phase difference adjuster, a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or dye, a fluorescent whitening agent, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, a solvent, etc. may be included. The thickness of the stretched retardation plate may be 200 µm or less, preferably 1 µm or more and 100 µm or less. When the thickness exceeds 200 µm, the flexibility may decrease. The λ/4 retardation layer is preferably the optical film of the present invention from the viewpoint of workability and flexibility.

Further, as another example of the λ/4 retardation layer, a liquid crystal coating type retardation plate formed by applying a liquid crystal composition may be used. The liquid crystal composition includes a liquid crystal compound having a liquid crystal state such as nematic, cholesteric, and smectic. Any one compound containing a liquid crystal compound in the liquid crystal composition has a polymerizable functional group. The liquid crystal coating type retardation plate may further contain an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal coating type retardation plate can be produced by forming a liquid crystal retardation layer by coating and curing a liquid crystal composition on an alignment film in the same manner as described in the liquid crystal polarizing layer. The liquid crystal coated retardation plate can be formed to have a thin thickness compared to the stretched retardation plate. The thickness of the liquid crystal polarizing layer may be 0.5 µm or more and 10 µm or less, preferably 1 µm or more and 5 µm or less.

The liquid crystal coating type retardation plate may be peeled off from the substrate and transferred to be laminated, or the substrate may be laminated as it is. It is also preferable that the substrate serves as a protective film, a retardation plate, or a transparent substrate for a window.

In general, the shorter the wavelength, the larger the birefringence, and the longer the wavelength, the smaller the birefringence. In this case, since it is not possible to achieve a retardation of λ/4 in the entire visible light region, the in-plane retardation of λ/4 is 100 nm or more and 180 nm or less, preferably 130 nm or more and 150 nm with respect to the vicinity of 560 nm with high visibility. It is often designed to be as follows. It is preferable to use an inversely dispersed λ/4 retardation layer using a material having a birefringence wavelength dispersion characteristic opposite to that of the usual because visibility can be improved. As such a material, in the case of an elongated retardation plate, it is preferable to use those described in Japanese Patent Laid-Open No. 2007-232873, and in the case of a liquid crystal coated retardation plate, those described in Japanese Unexamined Patent Publication No. 2010-30979.

In addition, as another method, a technique of obtaining a broadband λ/4 phase difference layer by combining with a 1/2 wavelength phase difference layer (hereinafter, also referred to as a λ/2 phase difference layer) is known (Japanese Patent Laid-Open No. 10-90521). The λ/2 retardation layer may also be the optical film of the present invention, or may be produced by the same material and method as the λ/4 retardation layer. Although the combination of the stretched retardation plate and the liquid crystal coated retardation plate is arbitrary, use of a liquid crystal coated retardation plate in either case is preferable because the film thickness can be reduced. The λ/2 retardation layer is preferably the optical film of the present invention from the viewpoint of workability and flexibility.

A method of laminating a positive C plate to a circular polarizing plate in order to increase visibility in an oblique direction is also known (Japanese Patent Laid-Open No. 2014-224837). The positive C plate may be also the optical film of the present invention, a liquid crystal coating type retardation plate or a stretched retardation plate may be used. The retardation in the thickness direction may be, for example, -200 nm or more and -20 nm or less, and preferably -140 nm or more and 40 nm or less. The positive C plate is preferably the optical film of the present invention from the viewpoint of workability and flexibility of the polarizing plate. The positive C plate can also be used as a retardation laminate in combination with a lambda /4 retardation layer.

(Touch sensor)

The touch sensor is used as an input means. As the touch sensor, various modes such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and a capacitance method have been proposed, and any method may be used. Among them, the electrostatic capacity method is preferable. The capacitive touch sensor is divided into an active area and an inactive area located at the outer periphery of the active area. The active area is an area corresponding to the area where the screen is displayed (display unit) on the display panel, and the inactive area is the area corresponding to the area where the screen is not displayed on the image display device (non-display area) to be. The touch sensor includes a substrate having a flexible characteristic; A sensing pattern formed in the active area of the substrate; Each sensing line is formed in the non-active region of the substrate and is connected to an external driving circuit through a sensing pattern and a pad portion. As the substrate having flexible properties, the same material as the transparent substrate for the window can be used. It is preferable that the substrate of the touch sensor has a toughness of 2,000 MPa% or more from the viewpoint of suppressing cracks of the touch sensor. More preferably, the toughness may be 2,000 MPa% or more and 30,000 MPa% or less.

The sensing pattern may have a first pattern formed in a first direction and a second pattern formed in a second direction. The first pattern and the second pattern are arranged in different directions. The first pattern and the second pattern are formed on the same layer, and each pattern must be electrically connected in order to sense a touched point. In the first pattern, each unit pattern is interconnected through a joint, but since the second pattern has a structure in which each unit pattern is separated from each other in the form of an island, a separate bridge electrode is used to electrically connect the second pattern. I need this. As the sensing pattern, a known transparent electrode material may be applied. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), PEDOT (poly(3,4-ethylenedioxythiophene)) , Carbon nanotubes (CNT), graphene, metal wires, and the like, and these may be used alone or in combination of two or more. Preferably, ITO can be used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, telenium, and chromium. These may be used alone or in combination of two or more.

The bridge electrode may be formed on the insulating layer through the insulating layer on the sensing pattern, and the bridge electrode may be formed on the substrate, and the insulating layer and the sensing pattern may be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, or may be formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of them. Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the joint portion of the first pattern and the bridge electrode, or may be formed in the structure of a layer covering the sensing pattern. In the latter case, the bridge electrode may connect the second pattern through a contact hole formed in the insulating layer.

The touch sensor is a means for appropriately compensating for a difference in transmittance between a patterned area in which a pattern is formed and a non-patterned area in which a pattern is not formed, specifically, a difference in light transmittance caused by a difference in refractive indices in these areas. As an example, an optical control layer may be further included between the substrate and the electrode, and the optical control layer may include an inorganic insulating material or an organic insulating material. The optical control layer may be formed by coating a photocurable composition including a photocurable organic binder and a solvent on a substrate. The photocurable composition may further include inorganic particles. The refractive index of the optical control layer can be increased by the inorganic particles.

The photocurable organic binder may include, for example, a copolymer of each monomer such as an acrylate-based monomer, a styrene-based monomer, and a carboxylic acid-based monomer. The photocurable organic binder may be a copolymer containing different repeating units such as an epoxy group-containing repeating unit, an acrylate repeating unit, and a carboxylic acid repeating unit. The inorganic particles may include, for example, zirconia particles, titania particles, alumina particles, and the like. The photocurable composition may further contain additives such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

(Adhesive layer)

Each layer (window, circular polarizing plate, touch sensor) and a film member constituting each layer (linear polarizing plate, λ/4 retardation plate, etc.) can be formed by an adhesive. Examples of adhesives include water-based adhesives, organic solvents, solvent-free adhesives, solid adhesives, solvent vaporizing adhesives, moisture curing adhesives, heat curing adhesives, anaerobic curing adhesives, active energy ray curing adhesives, curing agent mixture adhesives, heat melting adhesives, pressure sensitive adhesives. What is generally used, such as an adhesive (adhesive) and a rewet adhesive, can be used. Among them, a water-based solvent volatilization type adhesive, an active energy ray-curable adhesive, and an adhesive are often used. The thickness of the adhesive layer can be appropriately adjusted according to the required adhesion, etc., and is 0.01 µm or more and 500 µm or less, preferably 0.1 µm or more and 300 µm or less. You can do it.

As a water-based aqueous solvent volatilization type adhesive, a polymer in a water-dispersed state, such as a polyvinyl alcohol-based polymer, a water-soluble polymer such as starch, an ethylene-vinyl acetate-based emulsion, and a styrene-butadiene-based emulsion, can be used as the main polymer. In addition to water and the main polymer, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, and the like may be blended. In the case of bonding with a water-based water-based solvent volatilization-type adhesive, adhesion can be imparted by injecting a water-based water-based solvent volatilization-type adhesive between layers to be adhered to attach the adhered layer and then drying. In the case of using a water-based aqueous solvent volatilization type adhesive, the thickness of the adhesive layer may be 0.01 µm or more and 10 µm or less, preferably 0.1 µm or more and 1 µm or less. In the case of using a plurality of layers of a water-based aqueous solvent volatilization adhesive, the types of the thickness of each layer may be the same or different.

The active energy ray-curable adhesive can be formed by curing an active energy ray-curable composition containing a reactive material that forms an adhesive layer by irradiating with an active energy ray. The active energy ray curing composition may contain at least one polymer of a radical polymerizable compound and a cationic polymerizable compound such as a hard coat composition. The radical polymerizable compound is the same as the hard coat composition, and the same type of the hard coat composition can be used. The radical polymerizable compound used for the adhesive layer is preferably a compound having an acryloyl group. In order to lower the viscosity as an adhesive composition, it is also preferable to contain a monofunctional compound.

The cationic polymerizable compound is the same as the hard coat composition, and the same type of the hard coat composition can be used. As the cationic polymerizable compound used in the active energy ray curing composition, an epoxy compound is particularly preferable. It is also preferable to include a monofunctional compound as a reactive diluent in order to lower the viscosity as an adhesive composition.

The active energy ray composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cationic polymerization initiator, a radical and a cationic polymerization initiator, and the like, and can be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating, and generate radicals or cations to advance radical polymerization and cationic polymerization. Among those described in the hard coat composition, an initiator capable of initiating at least either radical polymerization or cationic polymerization by irradiation with active energy rays can be used.

The active energy ray curing composition may further include an ion trapping agent, an antioxidant, a chain transfer agent, an adhesion-imparting agent, a thermoplastic resin, a filler, a pour viscosity modifier, a plasticizer, a defoaming agent, a solvent, an additive, and a solvent. In the case of bonding with an active energy ray-curable adhesive, an active energy ray-curable composition is applied to one or both of the adhered layers, then bonded, and cured by irradiating active energy rays through either or both adhered layers. By making it possible to adhere. When an active energy ray-curable adhesive is used, the thickness of the adhesive layer may be 0.01 µm or more and 20 µm or less, preferably 0.1 µm or more and 10 µm or less. In the case of using a plurality of layers of an active energy ray-curable adhesive, the types of the thickness of each layer may be the same or different.

As the pressure-sensitive adhesive, it is classified into an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and the like, depending on the main polymer, and any one can be used. In addition to the main polymer, the pressure-sensitive adhesive may contain a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, and the like. Each component constituting the pressure-sensitive adhesive is dissolved and dispersed in a solvent to obtain a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive layer is formed by drying after coating the pressure-sensitive adhesive composition on a substrate. The adhesive layer may be formed directly or may be transferred to a separate substrate. It is also preferable to use a release film in order to cover the adhesive surface before adhesion. When an active energy ray-curable adhesive is used, the thickness of the adhesive layer may be 0.1 µm or more and 500 µm or less, and preferably 1 µm or more and 300 µm or less. In the case of using a plurality of pressure-sensitive adhesives, the types of thickness of each layer may be the same or different.

(Shading pattern)

The shading pattern can be applied as at least a part of a bezel or a housing of a flexible image display device. The light-shielding pattern hides the wiring arranged at the edge of the flexible image display device and makes it difficult to recognize the image, thereby improving the visibility of the image. The shading pattern may be in the form of a single layer or a multilayer. The color of the shading pattern is not particularly limited, and has various colors such as black, white, and metallic colors. The shading pattern may be formed of a pigment for realizing color and a polymer such as acrylic resin, ester resin, epoxy resin, polyurethane, and silicone. These may be used alone or as a mixture of two or more. The shading pattern can be formed by various methods such as printing, lithography, and inkjet. The thickness of the shading pattern may be 1 µm or more and 100 µm or less, and preferably 2 µm or more and 50 µm or less. In addition, it is also preferable to give a shape such as an inclination in the thickness direction of the light shielding pattern.

4 is a schematic cross-sectional view according to an embodiment of a flexible image display device. The circular polarizing plate 100 shown in FIG. 4 includes a front plate 101, a circular polarizing plate 102, a touch sensor 103, and an organic EL display panel 104 in this order.

Example

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples. In the examples, "%" and "parts" are mass% and mass parts unless otherwise specified. Various measurements and evaluations were performed as follows.

[Number of defects in the optically anisotropic layer]

<Confirmation of defects>

The obtained optical film was cut out into 50 mm x 50 mm, and the actual size and number of orientation defects on the screen were confirmed using an optical microscope (ECLIPSE ME600, manufactured by Nikon Corporation). When observing, a linear polarizing plate is inserted under the stage of the optical microscope. Then, the direction of the slow axis of the obtained optical film and the direction of the absorption axis of the linear polarizing plate inserted in the lower part of the stage are matched. In addition, the polarizer of the optical microscope was rotated to obtain a cross Nicol state, and the region which became a bright spot was made into an orientation defect. When the region was observed by releasing the polarization state, the length of the portion at which the dimension of the region as a visually recognized defect was maximized was measured as the actual size of the orientation defect. As a result of observation, all of the defects were due to crystals of the polymerizable liquid crystal compound. Table 2 shows the results. In addition, the actual size of the defects shown in Table 2 is the average value of the measured actual sizes. All of the cut-out optical films had 6 defects/mm 2 or less whose actual size exceeded 50 µm. In all examples, the actual size of the orientation defect was 20 μm or less.

<ECLIPSE observation setting>

Light illuminance: fully open

Stage lower aperture: 0.5

Exposure time: 200 ms

GAIN: 2.00

AWB: not set

[Defect rate of optically anisotropic layer]

After measuring the number of defects described above, an image of one field of view (including the defective portion) in the cross-Nicole state of an optical microscope is obtained with 256 gray scales between the brightest and darkest areas. As much as possible, the image received and received on a personal computer was binarized under the condition of a threshold value of 127 using image processing software attached to the personal computer, and the area of the orientation defect was calculated, and the defect rate was calculated. Table 2 shows the results.

[Measurement of stab strength]

For the prick test, a handy compression tester "KES-G5 needle penetration force measurement specification" manufactured by Katotech Co., Ltd. equipped with a needle with a spherical tip (tip diameter 1 mmφ, 0.5 R) was used, and the temperature was 23±3°C. Under the environment of, and under the measurement conditions of the piercing speed of 0.0033 cm/sec.

The piercing strength measured in the piercing test was taken as the average value by performing a piercing test on three test pieces. Table 2 shows the results.

[Measurement of tensile stress]

The tensile test was performed using the precision universal testing machine "Autograph AG-IS" manufactured by Shimadzu Corporation, in an environment at a temperature of 23±3°C and under measurement conditions of a tensile rate of 1 mm/min. The size of the optical film used for evaluation was 10 x 10 mm. Tensile tests were each performed in the slow axis direction or the direction perpendicular to the slow axis direction (that is, the fast axis direction) of the optical film. The tensile stress measured in the tensile test was subjected to a tensile test on three test pieces, and was taken as the average value. Table 2 shows the results.

[Liquid crystal composition solution]

A polymerizable liquid crystal compound (A-1) (molecular weight 1156), a polymerizable liquid crystal compound (B-1) (molecular weight 664), and a polymerizable liquid crystal compound (C-1) (molecular weight 1083) represented by the following formula were prepared.

Polymerizable liquid crystal compound (A-1):

Polymerizable liquid crystal compound (B-1):

Polymerizable liquid crystal compound (C-1):

The polymerizable liquid crystal compound (A-1) was synthesized by the method described in Japanese Unexamined Patent Application Publication No. 2011-207765.

The polymerizable compound (B-1) was synthesized by the method described in Japanese Patent Laid-Open No. 2010-24438.

The polymerizable compound (C-1) was synthesized by the method described in Japanese Patent Laid-Open No. 2010-24438.

83 parts by mass of the obtained polymerizable liquid crystal compound (A-1), 3 parts by mass of the polymerizable liquid crystal compound (B-1), and 14 parts by mass of the polymerizable liquid crystal compound (C-1) were mixed, and the liquid crystal mixture (1) (total amount 100) Mass parts) was obtained.

Referring to the patent document (Japanese Patent Laid-Open No. 2017-179367), according to the composition shown in Table 1, a liquid crystal mixture (1), a polymerization initiator, a leveling agent, a polymerization inhibitor, and a solvent were added to the liquid crystal composition solution (1). Prepared. Here, the amounts of the polymerization initiator, leveling agent, and polymerization inhibitor shown in Table 1 are the amounts to be charged per 100 parts by mass of the liquid crystal mixture (1). In addition, the blending amount of the solvent was set so that the mass% of the liquid crystal mixture (1) was 10 mass% with respect to the total amount of the liquid crystal composition solution [solvent so that 100 parts by mass of the liquid crystal mixture (1) is contained in 1000 parts by mass of the liquid crystal composition solution (1). Applied].

Polymerization initiator: 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one (Igacure 369; manufactured by BASF Japan)

Leveling agent: Polyacrylate compound (BYK-361N; manufactured by Big Chemistry Japan)

Polymerization inhibitor: BHT (manufactured by Wako Pure Chemical Industries, Ltd.)

Solvent: N-methylpyrrolidone (NMP; manufactured by Kanto Chemical Co., Ltd.)

[Composition for photo-alignment film formation]

The mixture obtained by mixing the following components was stirred at 80° C. for 1 hour to obtain a composition for forming a photo-alignment film (1). The photo-alignment material represented by the following formula was synthesized by the method described in Japanese Unexamined Patent Application Publication No. 2013-33248.

Photo-oriented material (5 parts):

Solvent (95 parts): Cyclopentanone

[Example 1]

An optical film was produced as follows. Cycloolefin polymer film (COP) (ZF-14, manufactured by Nippon Zeon Co., Ltd., thickness 23 µm, heat capacity per 1 cm 2 of substrate is 0.004 J/cm 2 ·°C), corona treatment device (AGF-B10, Kasuga Denki) (Manufactured by Co., Ltd.) was used once under the conditions of an output of 0.3 kW and a treatment speed of 3 m/min. On the surface subjected to the corona treatment, the composition for forming a photo-alignment film (1) was applied with a bar coater, dried at 80° C. for 1 minute, and a polarized UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Electric Corporation) was used. By using, polarized UV exposure was performed with the accumulated light quantity of 100 mJ/cm<2>. When the thickness of the obtained alignment film was measured with a laser microscope (LEXT, manufactured by Olympus Corporation), it was 100 nm.

Then, in an environment of room temperature 25°C and humidity 30%RH, the prepared liquid crystal composition solution (1) was passed through a PTFE membrane filter (manufactured by Adovantech Toyo Co., Ltd., part number; T300A025A) with a pore diameter of 0.2 μm, and obtained The liquid crystal composition solution (1) was applied on a substrate with an alignment film kept warm at 25°C using a bar coater, dried at 120°C for 1 minute, and then a high-pressure mercury lamp (Unicure VB-15201BY-A, Ushio Denki Co., Ltd.) Manufacturing), an optical film was produced by irradiating ultraviolet rays (under a nitrogen atmosphere, wavelength: 365 nm, accumulated light amount at a wavelength of 365 nm: 1000 mJ/cm 2 ). The thickness of the obtained coating film was measured with a laser microscope (LEXT, manufactured by Olympus Corporation) and found to be 2 µm.

[Example 2]

Except having coated while keeping the base material with alignment film warm at 40 degreeC, it carried out similarly to Example 1, and produced the optical film.

[Example 3]

An optical film was produced in the same manner as in Example 1, except that the obtained substrate with alignment film was heated at 80°C for 10 seconds before coating and then applied.

[Example 4]

An optical film in the same manner as in Example 1, except that the composition ratio of the polymerizable liquid crystal compound was 82 parts by mass, (B-1) 4 parts by mass, and (C-1) 14 parts by mass. I wrote.

[Example 5]

An optical film in the same manner as in Example 1, except that the composition ratio of the polymerizable liquid crystal compound was 77 parts by mass, (B-1) 9 parts by mass, and (C-1) 14 parts by mass. I wrote.

[Example 6]

As a base material, a soda glass plate having a thickness of 0.3 mm was bonded to the non-coated surface of COP (the surface to which the liquid crystal composition solution was not coated) with an adhesive. This substrate had a heat capacity of 0.05 J/cm2·°C per 1 cm2 of the substrate. Except having used this base material, it carried out similarly to Example 1, and produced the optical film.

[Comparative Example 1]

An optical film was produced in the same manner as in Example 1, except that the humidity at the time of coating was set to 65%RH.

[Comparative Example 2]

An optical film in the same manner as in Example 1, except that the composition ratio of the polymerizable liquid crystal compound was 99 parts by mass, (B-1) 1 part by mass, and (C-1) 0 parts by mass. I wrote.

[Comparative Example 3]

An optical film in the same manner as in Example 1, except that the composition ratio of the polymerizable liquid crystal compound was 92 parts by mass, (B-1) 3 parts by mass, and (C-1) 5 parts by mass. I wrote.

[Comparative Example 4]

As a base material, a soda glass plate having a thickness of 10 mm was bonded to the non-coated surface of COP with an adhesive. This substrate had a heat capacity of 1.68 J/cm2·°C per 1 cm2 of the substrate. Except having used this base material, it carried out similarly to Example 1, and produced the optical film.

[Phase difference laminate]

<Preparation of the first retardation layer>

Examples 1, 4 and 5 and Comparative Examples 2 and 3 were used as the first retardation layer.

<Preparation of the second retardation layer>

A PET substrate having a thickness of 38 μm was used as a transparent substrate, and a composition for a vertical alignment layer was coated on one side thereof so as to have a film thickness of 3 μm, and an alignment layer was produced by irradiation with ultraviolet rays. In addition, as the composition for the vertical alignment layer, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, dipentaerythritol triacrylate, and bis(2-vinyloxyethyl) ether of 1:1:4:5 The mixture was mixed at a rate, and a mixture in which LUCIRIN TPO was added at a rate of 4% as a polymerization initiator was used.

Next, on the formed alignment layer, a liquid crystal composition containing a photopolymerizable nematic liquid crystal (manufactured by Melk, RMM28B) was applied onto the alignment layer by die coating. Here, in the liquid crystal composition, methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) as solvents, and cyclohexanone (CHN) having a boiling point of 155° C. are used in a mass ratio (MEK:MIBK:CHN) of 35:30:35. A mixed solvent mixed at a ratio was used. Then, the liquid crystal composition prepared so that the solid content was 1 to 1.5 g was coated on the alignment layer so that the coating amount was 4 to 5 g (wet).

And after coating the liquid crystal composition on the alignment layer, drying treatment was performed by setting the drying temperature to 75 degreeC and the drying time to 120 seconds. Thereafter, polymerization was performed by ultraviolet (UV) irradiation to obtain a layer in which a photopolymerizable nematic liquid crystal compound was cured, an alignment layer, and a positive C layer including a transparent substrate. The total thickness of the layer on which the photopolymerizable nematic liquid crystal compound was cured and the alignment layer was 4 µm.

<Production of phase difference laminate>

The first retardation layer and the second retardation layer were bonded together with an ultraviolet-curable adhesive so that the respective retardation layer faces (the face opposite to the transparent substrate) became a bonding face. Subsequently, ultraviolet light was irradiated to cure the ultraviolet curable adhesive. In this way, a retardation laminate 1 including two retardation layers, a first retardation layer and a second retardation layer, was produced.

[Polarizer]

After immersing a polyvinyl alcohol film with an average polymerization degree of about 2400, a saponification degree of 99.9 mol% or more, and a thickness of 30 µm in pure water at 30°C, immersion in an aqueous solution having an iodine:potassium iodine:water mass ratio of 0.02:2:100 at 30°C. Then, iodine dyeing was performed (hereinafter, also referred to as an iodine dyeing step). The polyvinyl alcohol film subjected to the iodine dyeing step was immersed in an aqueous solution having a mass ratio of potassium iodide:boric acid:water of 12:5:100 at 56.5°C to perform boric acid treatment (hereinafter, also referred to as a boric acid treatment step). After washing the polyvinyl alcohol film subjected to the boric acid treatment step with pure water at 8°C, it was dried at 65°C to obtain a polarizer (12 µm in thickness after stretching) in which iodine is adsorbed and oriented to polyvinyl alcohol. At this time, stretching was performed in an iodine dyeing step and a boric acid treatment step. The total draw ratio in this drawing was 5.3 times.

To both surfaces of the obtained polarizer, a saponified triacetyl cellulose film (KC4UYTAC 40 µm manufactured by Konica Minolta Co., Ltd.) was adhered to each other with a nip roll through a water-based adhesive. The obtained bonded product was dried at 60° C. for 2 minutes while maintaining the tension at 430 N/m, thereby obtaining a polarizer (1) having a triacetyl cellulose film as a protective film on both sides. In addition, the water-based adhesive is 100 parts of water, 3 parts of carboxy-modified polyvinyl alcohol (Kurarepoval KL318 manufactured by Kuraray Co., Ltd.), and a water-soluble polyamide epoxy resin (Sumirez Resin manufactured by Taoka Chemical Industry Co., Ltd.). It was prepared by adding 1.5 parts of an aqueous solution having a 650 solid content concentration of 30%).

With respect to the obtained polarizer (1), optical properties were measured using a spectrophotometer (V7100, manufactured by Nippon Bunko Co., Ltd.). The obtained luminous sensitivity corrected monolith transmittance was 42.1%, luminous sensitivity corrected polarization degree was 99.996%, monolithic color a ^* was -1.1, monolithic color b ^* was 3.7.

[Polarizer]

A pressure-sensitive adhesive B was attached to one side of the polarizer 1 as a first pressure-sensitive adhesive layer, the separate film was peeled off, and the transparent substrate on the side of the first retardation layer of the retardation laminate 1 was laminated on the peeled side. A pressure-sensitive adhesive F was laminated as a second pressure-sensitive adhesive layer on a surface of the phase difference layered body 1 opposite to the surface of the polarizer stacked thereon. In this way, a polarizing plate including a protective film, a polarizer, a protective film, a first adhesive layer, a first phase difference layer, an adhesive layer, a second phase difference layer, and a second adhesive layer in this order was produced.

[Evaluation method of workability of polarizing plate]

When the obtained polarizing plate was cut into 100 mm×100 mm with a super cutter, the cut end surface was observed with an optical microscope, and 3 or more cracks were seen in the phase difference layered product ×, 1 or 2 cracks were shown. Was set to ◎. The crack lengths of the phase difference laminates generated at this time were all 300 µm to 400 µm, and there was no difference in length.

[Polarizing plate with polyimide film]

The separate film of the 2nd adhesive layer of the obtained polarizing plate was peeled off, and it laminated|stacked on the polyimide film (Ubegosan make, Upyrex S model number 75S) of 75 micrometers in thickness. In this way, a polarizing plate provided with a polyimide film including a protective film, a polarizer, a protective film, a first adhesive layer, a first phase difference layer, an adhesive layer, a second phase difference layer and a second adhesive layer, and a polyimide film in this order was prepared. did.

[A method for evaluating the bending resistance of a polarizing plate with a polyimide film]

When the obtained polarizing plate with polyimide film was cut into 100 mm×10 mm with a super cutter, and folded with 0.5 R so that the polyimide film was convex, five or more cracks were seen in the retardation layered layer ×, 1 to 4 The visible one was set as ○, and the invisible one was set as ◎. The length of the crack generated in Example 1 was 250 µm, and the length of the crack generated in Comparative Example 3 was 220 µm to 250 µm, and there was no difference in the length of the crack in Example 1 and Comparative Example 3.

Description of Reference Numerals 10: optical film, 11: optical anisotropic layer, 12: alignment layer, 13: base layer, 20: retardation laminate, 31: first base layer, 32: first alignment layer, 33: first retardation layer, 34: Adhesive layer, 35: second retardation layer, 36: second alignment layer, 37: second base layer, 38: adhesive layer, 39: polarizer, 40: polarizing plate.

Claims (12)

An optical film having an optically anisotropic layer comprising a polymer polymerized in a state in which a polymerizable liquid crystal compound having at least one polymerizable functional group is oriented,
An optical film characterized in that the number of orientation defects having an actual size of 0.3 µm or more and 50 µm or less per 1 mm 2 of the optically anisotropic layer satisfies the following formula (1).
0≤number of orientation defects[pcs]≤14 (1) An optical film having an optically anisotropic layer comprising a polymer polymerized in a state in which a polymerizable liquid crystal compound having at least one polymerizable functional group is oriented,
An optical film characterized in that the defect rate defined by the following formula (2) in the optically anisotropic layer satisfies the following formula (3).

[In the formula, the total defect area is the sum of the areas of orientation defects in which the actual size observed in one field of view of the optical microscope is 0.3 µm or more and 50 µm or less, and the observation field of the microscope is optically anisotropic in all one field of view of the optical microscope. It is the area of the optically anisotropic layer when the layer is present.]
0≤defect rate[ppm]≤1000 (3) An optical film having an optically anisotropic layer comprising a polymer polymerized in a state in which a polymerizable liquid crystal compound having at least one polymerizable functional group is oriented,
The number of orientation defects having an actual size of 0.3 µm or more and 50 µm or less per 1 mm 2 of the optically anisotropic layer satisfies the following formula (1), and the defect rate defined by the following formula (2) satisfies the following formula (3). Optical film, characterized in that.
0≤number of orientation defects[pcs]≤14 (1)

[In the formula, the total defect area is the sum of the areas of orientation defects in which the actual size observed in one field of view of the optical microscope is 0.3 µm or more and 50 µm or less, and the observation field of the microscope is optically anisotropic in the entire field of the optical microscope It is the area of the optically anisotropic layer when the layer is present.]
0≤defect rate[ppm]≤1000 (3) The optical film according to any one of claims 1 to 3, wherein the polymerizable functional group is an acryloyloxy group. The optical film according to any one of claims 1 to 4, wherein the alignment defect includes a defect caused by microcrystals of the polymerizable liquid crystal compound. The optical film according to any one of claims 1 to 5, wherein the optically anisotropic layer has a thickness of 0.05 µm or more and 10 µm or less. A retardation laminate comprising at least one optical film according to any one of claims 1 to 6. A polarizing plate comprising the retardation laminate according to claim 7. The polarizing plate according to claim 8, which has a cut surface. The polarizing plate according to claim 8 or 9, which is a release polarizing plate. The polarizing plate according to any one of claims 8 to 10, comprising at least one of a front plate and a touch sensor. A flexible image display device comprising the polarizing plate according to any one of claims 8 to 11.

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