JP2019194685A - Polarizing plate - Google Patents

Abstract

To provide a polarizing plate with at least one curved section.SOLUTION: A polarizing plate of the present invention comprises a polarizer with a first surface and a second surface, and a first base material disposed on the first surface of the polarizer, where the polarizer has a thickness of 15 μm or less and the first base material is a thermoplastic resin. The polarizing plate has at least one curved section.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polarizing plate.

  A polarizing plate is an optical element having a specific alignment structure. For example, Patent Document 1 discloses a polarizing film in which iodine or a dichroic dye is adsorbed on a polymer film typified by a film made of polyvinyl alcohol (PVA) or a derivative thereof, and this film is stretched and oriented uniaxially. ing.

JP 2007-047498 A

  The polarizing plate may be heat-molded depending on the application. For example, when a polarizing plate is bonded to a lens having a curved surface such as sunglasses, the polarizing plate is heat-molded while being bonded along the lens to give the polarizing plate a shape corresponding to the curved surface. However, when the polarizing plate is thermoformed, the following problems may occur.

  The thickness of the polarizer of the polarizing plate using the conventional stretched PVA is 20 μm to 30 μm, and when such a polarizing plate is heat-molded, the stretching force of the stretched PVA is large and the heat shrinks in the stretching direction. , It may tear along the stretching direction. In order to suppress such a phenomenon, in a polarizing plate using stretched PVA, it is necessary to bond the polarizing plate to a substrate such as a resin, or to fix the periphery of the polarizing plate with a curable resin.

  This invention is made | formed in view of the said situation, Comprising: Shrinkage | contraction by thermoforming is suppressed and it makes it a subject to provide the polarizing plate thinned.

The present invention includes the following aspects.
[1] A polarizing plate having a polarizer having a first surface and a second surface, and a first substrate disposed on the first surface of the polarizer, the polarizer comprising: A polarizing plate having a thickness of 15 μm or less, the first base material being a thermoplastic resin base material, and the polarizing plate having at least one curved portion.
[2] The polarizing plate according to [1], wherein a curvature radius of the curved portion is 30 mm to 150 mm.
[3] The polarizing plate according to [1] or [2], wherein the first base material includes at least one resin of an acrylic resin and a cyclic olefin resin.
[4] The polarizer includes a polarizing layer, and the polarizing layer includes a cured product of a liquid crystal compound and a dichroic dye, and the dichroic dye is dispersed and oriented in the polarizing layer [ The polarizing plate as described in any one of 1]-[3].
[5] The polarizing plate according to any one of [1] to [4], wherein the thickness of the first substrate is 40 μm to 120 μm.
[6] The polarizing plate according to any one of [1] to [5], further including a second base material on the second surface of the polarizer.
[7] The polarizing plate according to [6], wherein the second base material includes at least one selected from an acrylic resin, a cyclic olefin resin, and a triacetyl cellulose resin.
[8] Any one of [1] to [7], wherein the polarizing plate is used by being bonded to the display surface of a display device having a curved surface, and the curved portion matches the curved surface. The polarizing plate as described in one.

  ADVANTAGE OF THE INVENTION According to this invention, the shrinkage | contraction by thermoforming is suppressed and the polarizing plate thinned can be provided.

It is a schematic cross section of the polarizing plate in one Embodiment of this invention. It is a schematic cross section of the polarizing plate in one Embodiment of this invention. It is a schematic cross section of the circularly-polarizing plate in one Embodiment of this invention. It is a schematic cross section of the circularly-polarizing plate in one Embodiment of this invention.

  The polarizing plate in this embodiment is a polarizing plate having a polarizer having a first surface and a second surface, and a first substrate disposed on the first surface of the polarizer. The thickness of the polarizer is 15 μm or less, the first substrate is a thermosetting resin substrate, and the polarizing plate has at least one curved portion.

  Hereinafter, as an embodiment of the present invention, a case where the polarizing layer includes a cured product of a liquid crystal compound and a case where PVA is included will be described.

<First Embodiment>
FIG. 1 is a schematic cross-sectional view of a polarizing plate 1 according to this embodiment. The polarizing plate 1 includes a polarizer 11 and a first base material 12. The polarizer 11 has a first surface 31 and a second surface 32. The first substrate 12 is located on the first surface 31. The polarizer 11 includes a polarizing layer 21 and an alignment layer 22. The polarizing layer 21 includes a cured product 101 of a liquid crystal compound and a dichroic dye 102. The dichroic dye 102 is dispersed in a cured product 101 of a liquid crystal compound.
The alignment layer 22 exhibits an alignment regulating force. By disposing the liquid crystal compound before curing on the alignment layer 22, the liquid crystal compound before curing is aligned in one direction. Then, the cured product 101 of the liquid crystal compound aligned in one direction is obtained by curing the liquid crystal compound. Since the dichroic dye 102 is disposed on the alignment layer 22 in a state of being dispersed in the liquid crystal compound before curing, the dichroic dye 102 is also a cured product 101 of the liquid crystal compound according to the orientation of the cured product 101 of the liquid crystal compound. It is oriented in the orientation direction.

The polarizing plate 1 has at least one curved portion 13. The shape of the curved portion 13 depends on the shape of the object to which the polarizing plate 1 is bonded. In the present embodiment, the bending portion 13 may be a bending portion having a plurality of curvature radii. The radius of curvature in the present embodiment is defined by the surface closest to the virtual center in the curved portion 13. For example, the radius of curvature in the polarizing plate 1 of FIG. 1 is defined as the radius of curvature of the second surface 32. The radius of curvature is a value obtained from the arc length, chord length, and arrow height of the curved portion 13 using the following formula.
Arc length (L) = radius (r) * center angle (θ) (1)
String length (d) = 2 * r * sin (θ / 2) (2)
Yataka (h) = r * {1-cos (θ / 2)} (3)

  The curvature radius of the curved portion 13 may be, for example, 30 mm to 150 mm. The polarizing plate 1 may have two or more curved portions 13. Although the shape of the curved part 13 is not specifically limited, For example, the curved part which has a small curvature radius which could not be followed with the polarizing plate containing extending | stretching PVA may be sufficient.

  In addition, in the polarizing plate using the stretched PVA having a thickness of 20 μm to 30 μm as the polarizing layer, it may be thermally shrunk in the stretching direction of the stretched PVA or torn along the stretching direction of the stretched PVA during the heat molding. There is. In order to suppress such a phenomenon, it is necessary to hold | maintain a polarizing plate with the 2nd base material for maintaining a shape.

  When the polarizer 1 of the polarizing plate 1 is obtained by aligning the cured product 101 of the liquid crystal compound and the dichroic dye 102, stretching is not necessary. Therefore, the shrinkage by heat is small compared with the polarizing plate containing the extending | stretching PVA whose thickness is 20 micrometers-30 micrometers conventionally. From this, when the polarizing plate using the stretched PVA having a conventional thickness of 20 μm to 30 μm is heat-molded, the second base material used for maintaining the shape is thinned or omitted. Can do. The polarizing plate 1 can be bonded to an object having a more complicated shape, and contributes to an improvement in the design of the object.

  When the polarizer 1 of the polarizing plate 1 is obtained by aligning the cured product 101 of the liquid crystal compound and the dichroic dye 102, the bending strength does not vary depending on the bending direction at the time of heat molding. Therefore, it can be pasted also on the object which has a more complicated shape, and it contributes to the improvement of the design nature of an object.

  The thickness of the polarizing plate 1 is 25 μm to 200 μm, preferably 50 μm to 180 μm, and more preferably 60 μm to 170 μm. By setting the thickness of the polarizing plate 1 to 60 μm to 170 μm, the followability to the shape of the object to which the polarizing plate 1 is bonded becomes good. The thickness of the polarizing plate 1 in this embodiment is defined as a value obtained by measuring an arbitrary five points in the polarizing plate 1 with a contact-type film thickness meter and calculating an average thereof.

  The thickness of the polarizer 11 is 1 μm or more and 15 μm or less, preferably 1 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less, and further preferably 1 μm or more and 3 μm or less. In the present embodiment, the thickness of the polarizer 11 is determined by measuring any five points of the polarizer 11 with a contact film thickness meter, an interference film thickness meter, a laser microscope or a stylus film thickness meter, and calculating an average value thereof. It can be obtained by calculating.

  Since the polarizing plate 1 of this embodiment includes the cured product 101 of the liquid crystal compound and the polarizing layer 21 in which the dichroic dye 102 is aligned, the polarization characteristics are not easily changed even when the polarizing plate 1 is heated. The holding ratio of the polarization property of the polarizing plate 1 before and after heating is, for example, 90% to 100%, and preferably 95% to 100%. In the present embodiment, the polarization property retention ratio of the polarizing plate 1 before and after heating can be calculated as the absorbance retention ratio (%) in the orientation direction (also referred to as the absorption axis direction) of the dichroic dye 102.

Specifically, it is defined as follows. First, the absorbance A1 in the absorption axis direction of the polarizing plate 1 at 23 ° C. is measured (A1 (23 ° C.)). Measure A1 (23 ° C.) in a wavelength range of 2 nm steps 380 to 680 nm by a double beam method using a device in which a folder with a polarizing plate 1 attached is set on a spectrophotometer (Shimadzu Corporation UV-3150). To do. In addition, in order to remove the contribution of the light loss due to the surface reflection of the polarizing plate 1, after setting the measurement sample, the measurement is performed after correcting the zero point at 800 nm with no light absorption. Thereafter, the sample is put into an oven at 85 ° C. for 500 hours, and after taking out, the absorbance is measured again by the above method. Absorbance retention (%) is calculated by the following formula (I).
Absorbance retention (%) = A1 (85 ° C.) / A1 (23 ° C.) × 100 (I)
In the formula, A1 (85 ° C) is the absorbance in the absorption axis direction after holding the polarizing plate in an oven at 85 ° C for 500 hours, and A1 (23 ° C) is measured at 23 ° C before the heat resistance test. Absorbance in the direction of the absorption axis is shown.

  Since the polarizer 1 is as thin as 15 μm or less, the contraction due to heating is small as compared with a polarizer including stretched PVA having a thickness of 20 μm to 30 μm as a polarizer. Further, when the cured product 101 of the liquid crystal compound and the polarizing layer 21 in which the dichroic dye 102 is oriented, the shrinkage due to heating is smaller. Therefore, there is little variation in the polarization characteristics even at a plurality of arbitrary points in the curved portion 13 even after heat molding.

  FIG. 2 is a schematic cross-sectional view of a polarizing plate in one embodiment of the present invention. As shown in FIG. 2, the polarizing plate 1 ′ has the second substrate 14 positioned on the second surface 32 of the polarizer 11. The polarizer 11 can be protected by the second base material 14. Specifically, when the polarizer 11 is directly touched with a hand, scratches or the like may occur, and the polarization characteristics of only that portion may deteriorate. The second substrate 14 can prevent such a decrease in polarization characteristics.

Below, each element contained in the polarizing plate 1 is demonstrated in detail.
1. Polarizer The polarizer according to the present embodiment has a polarizing layer in which a dichroic dye and a cured product of a liquid crystal compound are aligned. This polarizing layer can be formed using a composition containing a dichroic dye (hereinafter, sometimes referred to as “polarizer-forming composition”). In this embodiment, the liquid crystal compound may also serve as a dichroic dye, that is, the liquid crystal compound may exhibit dichroism. As a liquid crystal compound which shows dichroism, the compound described in WO2011 / 024891 and Unexamined-Japanese-Patent No. 2018-120229 is illustrated, for example.

1-1. Dichroic dye As the dichroic dye, those having absorption within a wavelength range of 380 nm to 800 nm can be used, and an organic dye is preferably used. Examples of the dichroic dye include azo compounds.

  Examples of the azo compound include a dichroic dye (1) having an absorption maximum in a wavelength range of 380 nm to 550 nm. Examples of the dichroic dye (1) include a compound represented by the following formula (1) (hereinafter sometimes referred to as “compound (1)”). Trans is preferable for the geometric isomerism of the azobenzene moiety of the compound (1).

  Y in formula (1) is a group represented by the following formula (Y1) or formula (Y2), and preferably a group represented by formula (Y1).

In Formula (Y1) and Formula (Y2), the straight lines at both ends represent a bond, the bond on the left is bonded to a phenylene group having an azo group, and the bond on the right is phenylene having R ² Bonded to a group. L is an oxygen atom or -NR-, and R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group. Among these, L is preferably an oxygen atom or —NH—, and more preferably an oxygen atom.

R ¹ is a group represented by the following formula (R ¹ -1), formula (R ¹ -2) or formula (R ¹ -3), and preferably the formula (R ¹ -2) and the formula (R ¹ -3). * In the formula represents a bond.

It is preferable that ma in the group represented by the formula (R ¹ -2) is independently an integer of 0 to 10, and more preferably an integer of 0 to 5. The two mas may be the same or different, but are preferably the same.

R ² represents formula (R ² -1), formula (R ² -2), formula (R ² -3), formula (R ² -4), formula (R ² -5) or formula (R ² -6). ) with a group represented by the formula ^(R 2 -2), a group represented by the formula ^(R 2 -5) or formula ^(R 2 -6) preferably by the formula ^(R 2 -6) It is more preferable that it is a group represented.

When R ² is a group represented by the formula (R ² -1), formula (R ² -2), formula (R ² -3), formula (R ² -5) or formula (R ² -6) In addition, mb contained in the group is preferably an integer of 0 to 10, and more preferably an integer of 0 to 5.

  Examples of the compound (1) include compounds represented by the following formulas (1-1) to (1-8).

  Among these, compounds represented by formula (1-1), formula (1-2), formula (1-3), formula (1-5), formula (1-7) and formula (1-8) are preferable. The compounds represented by formula (1-1), formula (1-2), formula (1-3) and formula (1-7) are more preferred.

  Here, the manufacturing method of a compound (1) is demonstrated. Compound (1) is produced, for example, from the compound represented by formula (1X) [compound (1X)] and the compound represented by formula (1Y) [compound (1Y)] by the reaction shown in the following scheme. can do.

In the above scheme, R ¹ , R ² and Y have the same meaning as described above, and Re ¹ and Re ² are groups that react with each other to form a group represented by Y. Examples of the combination of Re ¹ and Re ² include a combination of a carboxy group and a hydroxyl group, a combination of a carboxy group and an amino group (such an amino group may be substituted with R), a carbonyl halide group and a hydroxyl group, Combinations of halide groups and amino groups (such amino groups may be substituted with R), combinations of carbonyloxyalkyl groups and hydroxyl groups, carbonyloxyalkyl groups and amino groups (such amino groups are substituted with R May be included). Further, here, the compound (1X) having R ¹ and the compound (1Y) having R ² will be described, but a compound in which R ¹ is protected with an appropriate protecting group, and R ² is protected with an appropriate protecting group. Compound (1) can also be produced by reacting the compounds with each other and then performing an appropriate deprotection reaction.

  As the reaction conditions for reacting the compound (1X) and the compound (1Y), optimum known conditions can be appropriately selected according to the types of the compound (1X) and the compound (1Y) to be used.

For example, the reaction conditions when Re ¹ is a carboxy group, Re ² is a hydroxyl group, and Y is —C (═O) —O— are, for example, in a solvent in the presence of an esterification condensing agent. The conditions to condense are mentioned. Examples of the solvent include solvents that can dissolve both the compound (1X) and the compound (1Y), such as chloroform. Examples of the esterification condensing agent include diisopropylcarbodiimide (IPC). Here, a base such as dimethylaminopyridine (DMAP) is preferably used in combination. Although reaction temperature is selected according to the kind of compound (1X) and compound (1Y), the range of -15-70 degreeC is mentioned, for example, Preferably it is the range of 0-40 degreeC. Examples of the reaction time include a range of 15 minutes to 48 hours.

  As for the reaction time, the reaction mixture during the reaction is appropriately sampled, and the degree of disappearance of the compound (1X) and the compound (1Y) and the production of the compound (1) by a known analytical means such as liquid chromatography or gas chromatography. It is also possible to determine by checking the degree.

  From the reaction mixture after the reaction, the compound (1) can be taken out by a known method such as recrystallization, reprecipitation, extraction and various chromatography, or by combining these operations.

  As the azo compound, a dichroic dye (2) having an absorption maximum in a wavelength range of 550 nm to 700 nm can be used.

  The dichroic dye (2) is a dichroic dye (2-1) having an absorption maximum in a wavelength range of 550 nm to 600 nm and / or a dichroic dye having an absorption maximum in a wavelength range of 600 nm to 700 nm (2- 2) may be included. The dichroic dye (2-1) preferably has an absorption maximum in the wavelength range of 570 nm to 600 nm, and the dichroic dye (2-2) more preferably has an absorption maximum in the wavelength range of 600 nm to 680 nm.

  Examples of the dichroic dye (2) include a compound represented by the following formula (2) (hereinafter sometimes referred to as “compound (2)”). Trans is preferable for the geometric isomerism of the azobenzene moiety of the compound (2). In the formula (2), n is 1 or 2.

Ar ¹ and Ar ³ are each independently a group represented by the formula (AR-1), the formula (AR-2), the formula (AR-3), or the formula (AR-4). * Represents a bond.

Ar ² is a group represented by formula (AR2-1), formula (AR2-2), or formula (AR2-3).

A ₁ and A ₂ are each independently a group represented by any one of formulas (A-1) to (A-9). In formula (A-2), formula (A-3), formula (A-5) and (A-6), mc is an integer of 0 to 10, and when two mc are present in the same group, The two mcs are the same or different from each other.

The compound (2) that can be used as the dichroic dye (2-1) is determined by combining Ar ¹ , Ar ^2, and Ar ³ so that the compound (2) has an absorption maximum in the wavelength range of 550 nm to 600 nm. It is done. Similarly, the compound (2) that can be used as the dichroic dye (2-2) by combining Ar ¹ , Ar ² and Ar ³ so that the compound (2) has absorption in the wavelength range of 600 nm to 700 nm. Is determined.

  Specific examples of the compound (2) include compounds represented by formulas (2-11) to (2-37), respectively.

  Among the specific examples of the compound (2), examples of the dichroic dye (2-1) include the formula (2-12), the formula (2-13), the formula (2-18), and the formula (2-20). ), Formula (2-21), formula (2-22), formula (2-23), formula (2-24), formula (2-26), formula (2-27), formula (2-28) , Formula (2-29), formula (2-30), and formula (2-37), respectively, and the dichroic dye (2-2) includes formula (2-31), Applicable are those represented by formula (2-32), formula (2-33), formula (2-34), formula (2-35) and formula (2-36), respectively. The compounds represented by formula (2-11), formula (2-15) and formula (2-16) are not dyes which absorb at wavelengths of 550 nm to 700 nm, but are used in combination with other dichroic dyes. can do.

  Among the specific examples of the compound (2), as the dichroic dye (2), the formula (2-15), the formula (2-16), the formula (2-18), the formula (2-20), the formula (2), 2-21), Formula (2-22), Formula (2-23), Formula (2-27), Formula (2-29), Formula (2-31), Formula (2-32), Formula (2) -33), formula (2-34), formula (2-35) and formula (2-37) are preferred.

  The dichroic dye (2) is produced by a known method described in, for example, JP-A-58-38756, JP-A-63-301850 and the like.

The above-mentioned dichroic dyes may be used alone or in combination of two or more.
When the composition for forming a polarizer contains two or more dichroic dyes, each content of the dichroic dye is expressed as a content with respect to 100 parts by mass of the polymerizable liquid crystal compound described later, and 3 parts by mass or less. Is preferable, 0.1 to 2.5 parts by mass is more preferable, and 1 to 1.5 parts by mass is more preferable. If each content of the dichroic dye is within the above range, the dichroic dye in the composition for forming a polarizer exhibits sufficient solubility in a solvent. When a polarizer is manufactured, a polarizer free from defects is easily obtained. This makes it easier to produce a polarizing plate having high light absorption selection performance even in a thin film and excellent in heat resistance. The total amount of the dichroic dye contained in the composition for forming a polarizer is represented by a content with respect to 100 parts by mass of the polymerizable liquid crystal compound to be described later, preferably 9 parts by mass or less, and 0.1 parts by mass to 7.5 parts by mass. More preferred is 1 part by mass or more and 4.5 parts by mass or less.

1-2. Liquid Crystal Compound A polarizer 11 according to this embodiment includes a polarizing layer 21 including a cured product 101 of a liquid crystal compound and a dichroic dye 102. That is, the said polarizer formation composition contains a liquid crystal compound with a dichroic dye.

A polymerizable liquid crystal compound is mentioned as a liquid crystal compound in this embodiment. The polymerizable liquid crystal compound is a liquid crystal compound that can be polymerized while being aligned, and has a polymerizable group in the molecule. A composition for forming a polarizer containing a polymerizable liquid crystal compound forms a cured film by polymerizing the polymerizable liquid crystal compound in an aligned state. The cured film, that is, the cured product 101 of the liquid crystal compound does not need to exhibit liquid crystallinity. The polymerizable group is particularly preferably a radical polymerizable group.
A radically polymerizable group means a group involved in a radical polymerization reaction.

  Even though the polymerizable liquid crystal compound exhibits a nematic liquid crystal phase (hereinafter, sometimes referred to as “nematic liquid crystal phase”), it is a smectic liquid crystal phase (hereinafter, sometimes referred to as “smectic liquid crystal phase”). Or a nematic liquid crystal phase and a smectic liquid crystal phase, but at least a polymerizable smectic liquid crystal compound exhibiting a smectic liquid crystal phase is preferable. In the composition for forming a polarizer containing a polymerizable smectic liquid crystal compound, the coloring is suppressed by the interaction with the dichroic dye, and a polarizer having more excellent polarization performance is obtained.

  As the smectic liquid crystal phase exhibited by the polymerizable smectic liquid crystal compound, a higher order smectic liquid crystal phase is more preferable. The high-order smectic liquid crystal phase here means a smectic B phase, a smectic D phase, a smectic E phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic I phase, a smectic J phase, a smectic K phase, and a smectic L phase. Among them, a smectic B phase, a smectic F phase, and a smectic I phase are more preferable.

When the smectic liquid crystal phase exhibited by the polymerizable liquid crystal compound is a higher-order smectic liquid crystal phase, a polarizer having a higher degree of alignment order can be produced. In addition, a polarizer prepared using a polymerizable liquid crystal compound that is a high-order smectic liquid crystal phase having a high degree of orientational order has a Bragg peak derived from a higher-order structure such as a hexatic phase or a crystal phase in X-ray diffraction measurement. can get. This Bragg peak is a peak derived from the surface periodic structure of molecular orientation.
According to the composition for forming a polarizer according to this embodiment, a polarizer having a periodic interval of 3.0 to 5.0 mm can be obtained.

  Whether the polymerizable liquid crystal compound exhibits a nematic liquid crystal phase or a smectic liquid crystal phase can be confirmed, for example, as follows. A suitable base material is prepared, and a composition for forming a polarizer is applied to the base material to form a coating film. Thereafter, the solvent contained in the coating film is removed by heat treatment or reduced pressure treatment under conditions where the polymerizable liquid crystal compound is not polymerized. Subsequently, the coating film formed on the substrate is heated to an isotropic phase temperature, and the liquid crystal phase that is expressed by gradually cooling is examined by texture observation using a polarizing microscope. In this inspection, for example, a polymerizable liquid crystal compound that exhibits a nematic liquid crystal phase by cooling and further exhibits a smectic liquid crystal phase by further cooling is particularly preferable. Whether the polymerizable liquid crystal compound and the dichroic dye are not phase-separated in the nematic liquid crystal phase and the smectic liquid crystal phase can be confirmed by, for example, surface observation with various microscopes or scattering degree measurement with a haze meter.

Examples of the polymerizable liquid crystal compound include a compound represented by the formula (4) (hereinafter sometimes referred to as “compound (4)”).
^{U 1 -V 1 -W 1 -X 1} -Y 1 -X 2 -Y 2 -X 3 -W 2 -V 2 -U 2 (4)

In formula (4), X ¹ , X ² and X ³ are each independently a 1,4-phenylene group which may have a substituent or cyclohexane-1,4 which may have a substituent. -Represents a diyl group. At least one of X ¹ , X ² and X ³ is preferably a cyclohexane-1,4-diyl group which may have a substituent, and X ¹ or X ³ has a substituent. Particularly preferred is a cyclohexane-1,4-diyl group. —CH ₂ — constituting the optionally substituted cyclohexane-1,4-diyl group may be replaced by —O—, —S— or —NR—. R is a C1-C6 alkyl group or a phenyl group.

The cyclohexane-1,4-diyl group which may have a substituent is preferably a trans-cyclohexane-1,4-diyl group which may have a substituent. It is more preferable that it is a trans-cyclohexane-1,4-diyl group which does not have a structure. In the formula (4), at ^{least two of} X ¹ , X ² and X ³ may be a 1,4-phenylene group which may have a substituent, or 1,4 which has no substituent. -A phenylene group is preferred.

  Examples of the substituent that the optionally substituted 1,4-phenylene group or the optionally substituted cyclohexane-1,4-diyl group include, for example, methyl group, ethyl Group, a C1-C4 alkyl group, such as a butyl group, a cyano group, and a halogen atom.

Wherein (4), ^{Y 1} and ^{Y 2,} independently of one _{another, -CH 2 CH 2 -, -} CH 2 O -, - COO -, - OCOO-, a single bond, -N = N -, - CR a = CR ^b- , -C≡C- or -CR ^a = N-. R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y ¹ is preferably —CH ₂ CH ₂ —, —COO— or a single bond, and Y ² is preferably —CH ₂ CH ₂ —, —COO— or —CH ₂ O—.

In formula (4), U ¹ is a hydrogen atom or a polymerizable group, preferably a polymerizable group. U ² is a polymerizable group. U ¹ and U ² are both preferably a polymerizable group, and more preferably a photopolymerizable group. The photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical, an acid, or the like generated from a photopolymerization initiator described later. The polymerizable liquid crystal compound having a photopolymerizable group is advantageous in that it can be polymerized under a lower temperature condition.

The polymerizable groups of U ¹ and U ² may be different from each other, but are preferably the same type. Examples of the polymerizable group include a vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, and oxetanyl group. Among these, as the polymerizable group, 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.

In Formula (4), V ¹ and V ² each independently represent a C 1-20 alkanediyl group which may have a substituent, and —CH ₂ — constituting this alkanediyl group is , -O-, -S- or -NH- may be substituted. Examples of the alkanediyl group having 1 to 20 carbon atoms include methylene group, ethylene group, propane-1,3-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, and pentane-1. , 5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, decane-1,10-diyl group, tetradecane-1,14-diyl group And icosane-1,20-diyl group. V ¹ and V ² are preferably alkanediyl groups having 2 to 12 carbon atoms, and more preferably alkanediyl groups having 6 to 12 carbon atoms. As a substituent which a C1-C20 alkanediyl group has arbitrarily, a cyano group and a halogen atom can be mentioned, for example. This alkanediyl group is preferably unsubstituted, more preferably unsubstituted and linear.

In Formula (4), W ¹ and W ² each independently represent a single bond, —O—, —S—, —COO— or —OCOO—, preferably a single bond or —O—.

  Examples of compound (4) include compounds represented by formula (4-1) to formula (4-43). When the specific example of the compound (4) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably a trans isomer.

  The polymerizable liquid crystal compound can be used alone or in a mixture of two or more for the composition for forming a polarizer. When mixing 2 or more types of polymeric liquid crystal compounds, it is preferable in at least 1 type being a compound (4). As a mixing ratio when two kinds of polymerizable liquid crystal compounds are mixed, the ratio of polymerizable liquid crystal compound other than compound (4): compound (4) is usually 1:99 to 50:50, preferably 5:95. It is -50: 50, More preferably, it is 10: 90-50: 50.

  Among the compounds (4), formula (4-5), formula (4-6), formula (4-7), formula (4-8), formula (4-9), formula (4-10), formula (4-11), Formula (4-12), Formula (4-13), Formula (4-14), Formula (4-15), Formula (4-22), Formula (4-24), Formula ( 4-25), a formula (4-26), a formula (4-27), a formula (4-28), and a compound denoted by a formula (4-29) are preferred. These compounds can easily polymerize under the temperature conditions below the crystal phase transition temperature, that is, while maintaining the liquid crystal state of the higher order smectic phase sufficiently by interaction with other polymerizable liquid crystal compounds. Can do. Specifically, these compounds can be polymerized under a temperature condition of 70 ° C. or less, preferably 60 ° C. or less, while sufficiently maintaining a liquid crystal state of a higher order smectic phase.

  The content of the polymerizable liquid crystal compound in the composition for forming a polarizer is preferably 50% by mass to 99.9% by mass, and preferably 80% by mass to 99.9% by mass with respect to the solid content of the composition for forming a polarizer. Is more preferable. If the content rate of a polymeric liquid crystal compound is in the said range, there exists a tendency for the orientation of a polymeric liquid crystal compound to become high. Solid content means the total amount of the component remove | excluding volatile components, such as a solvent, from the composition for polarizer formation.

  Polymerizable liquid crystal compounds are described in, for example, Lub et al. Recl. Trav. Chim. It is manufactured by a known method described in Pays-Bas, 115, 321-328 (1996), Japanese Patent No. 4719156, and the like.

1-3. Solvent The composition for forming a polarizer preferably contains a solvent. As the solvent, a solvent capable of completely dissolving the dichroic dye and the polymerizable liquid crystal compound is preferable. Moreover, it is preferable that it is a solvent inactive to the polymerization reaction of the polymeric liquid crystal compound contained in the composition for polarizer formation.

  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; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ -Ester solvents such as butyrolactone, 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; tetrahydride Furan and ether solvents such as dimethoxyethane; and chloroform and chlorine-containing solvents such as chlorobenzene and the like. These solvents may be used alone or in combination of two or more.

  The content of the solvent is preferably 50% by mass to 98% by mass with respect to the total amount of the composition for forming a polarizer. In other words, the solid content in the composition for forming a polarizer is preferably 2% by mass to 50% by mass. When the solid content is 2% by mass or more, a thin polarizing plate which is one of the objects of the present embodiment is easily obtained. Further, when the solid content is 50% by mass or less, the viscosity of the composition for forming a polarizer is lowered, and therefore, the thickness of the polarizer becomes substantially uniform, so that unevenness in the polarizer hardly occurs. The solid content can be determined in consideration of the thickness of the polarizer.

1-4. Additive The composition for forming a polarizer according to the present embodiment can optionally contain an additive. Examples of the additive include a polymerization initiator, a photosensitizer, a polymerization inhibitor, and a leveling agent.

1-4-1. Polymerization initiator The composition for forming a polarizer preferably contains a polymerization initiator. The polymerization initiator is a compound that can initiate a polymerization reaction of the polymerizable liquid crystal compound. As the polymerization initiator, a photopolymerization initiator is preferable in that the polymerization reaction can be initiated under low temperature conditions. Specifically, a compound that generates an active radical or an acid by the action of light is used as a photopolymerization initiator. Among the photopolymerization initiators, those that generate active radicals by the action of light are more 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.

  Examples of the benzophenone compound include benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, 3,3 ′, 4,4′-tetra (tert-butylperoxycarbonyl). ) Benzophenone and 2,4,6-trimethylbenzophenone.

  Examples of the alkylphenone compound include diethoxyacetophenone, 2-methyl-2-morpholino-1- (4-methylthiophenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl). ) Butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1 -[4- (2-hydroxyethoxy) phenyl] propan-1-one, 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane-1- ON oligomers.

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

  Examples of the triazine compound include 2,4-bis (trichloromethyl) -6- (4-methoxyphenyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (4-methoxy Naphthyl) -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 (trichloro Methyl)- - [2- (3,4-dimethoxyphenyl) ethenyl] -1,3,5-triazine.

  A commercially available polymerization initiator can also be used. Examples of commercially available polymerization initiators include “Irgacure 907”, “Irgacure 184”, “Irgacure 651”, “Irgacure 819”, “Irgacure 250”, “Irgacure 369” (BASF Japan Ltd.); “Sequel BZ”, “Sequential Z”, “Sequential BEE” (Seiko Chemical Co., Ltd.); “Kayacure BP100” (Nippon Kayaku Co., Ltd.); “UVI-6992” (manufactured by Dow Chemical Company); "Adekaoptomer SP-152", "Adekaoptomer SP-170" (ADEKA); "TAZ-A", "TAZ-PP" (DKSH Japan); and "TAZ-104" ((stock) ) Sanwa Chemical).

  When the composition for forming a polarizer contains a polymerization initiator, the content can be appropriately adjusted according to the type and amount of the polymerizable liquid crystal compound contained in the composition for forming a polarizer, but usually the polymerization is performed. The content of the polymerization initiator with respect to 100 parts by mass of the total liquid crystalline compound is 0.1 parts by mass to 30 parts by mass, preferably 0.5 parts by mass to 10 parts by mass, and more preferably 0.5 parts by mass. Part to 8 parts by mass. If the content of the polymerizable initiator is within this range, it can be polymerized without disturbing the orientation of the polymerizable liquid crystal compound, which is preferable.

1-4-2. Photosensitizer When the composition for forming a polarizer contains a photopolymerization initiator, it may further contain a photosensitizer. Examples of the photosensitizer include anthracene such as xanthone compounds such as xanthone and thioxanthone (for example, 2,4-diethylthioxanthone and 2-isopropylthioxanthone); anthracene and anthracene containing an alkoxy group (for example, dibutoxyanthracene). Compounds; phenothiazine and rubrene.

  When the composition for forming a polarizer contains a photopolymerization initiator and a photosensitizer, the polymerization reaction of the polymerizable liquid crystal compound contained in the composition for forming a polarizer is further promoted. The content of the photosensitizer can be appropriately adjusted according to the type and amount of the photopolymerization initiator and the polymerizable liquid crystal compound to be used together, but is usually 0 with respect to 100 parts by mass of the polymerizable liquid crystal compound. 0.1 parts by mass to 30 parts by mass, preferably 0.5 parts by mass to 10 parts by mass, and more preferably 0.5 parts by mass to 8 parts by mass.

1-4-3. Polymerization inhibitor The composition for forming a polarizer may contain a polymerization inhibitor in order to allow the polymerization reaction of the polymerizable liquid crystal compound to proceed stably. The progress 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 (for example, butylcatechol), pyrogallol, 2,2,6,6-tetramethyl-1-piperidinyloxy radical, and the like. Supplementary agents; thiophenols; β-naphthylamines and β-naphthols.

When the composition for forming a polarizer contains a polymerization inhibitor, the content is appropriately adjusted according to the type and amount of the polymerizable liquid crystal compound used, the content of the photosensitizer, etc. It is 0.1-30 mass parts with respect to 100 mass parts of polymeric liquid crystal compound content, Preferably it is 0.5-10 mass parts, More preferably, it is 0.5-8 mass parts. Part by mass.
If the content of the polymerization inhibitor is within the above range, it can be polymerized without disturbing the orientation of the polymerizable liquid crystal compound contained in the composition for forming a polarizer, which is preferable.

1-4-4. Leveling agent It is preferable that the composition for forming a polarizer contains a leveling agent. The leveling agent has a function of adjusting the fluidity of the composition for forming a polarizer and flattening a coating film obtained by applying the composition for forming a polarizer, and includes a surfactant and the like. be able to. As a leveling agent, the leveling agent which has a polyacrylate compound as a main component and the leveling agent which has a fluorine atom containing compound as a main component is mentioned, for example.

  Examples of leveling agents mainly composed of a polyacrylate compound include “BYK-350”, “BYK-352”, “BYK-353”, “BYK-354”, “BYK-355”, and “BYK-358N”. , “BYK-361N”, “BYK-380”, “BYK-381”, and “BYK-392” [BYK Chemie].

  Examples of the leveling agent mainly composed of a fluorine atom-containing compound include MegaFuck “R-08”, “R-30”, “R-90”, “F-410”, “F-411”, “F”. -443 "," F-445 "," F-470 "," F-471 "," F-477 "," F-479 "," F-482 "and" F-483 "[DIC Corporation ] Surflon "S-381", "S-382", "S-383", "S-393", "SC-101", "SC-105", "KH-40" and "SA-100" [AGC Seimi Chemical Co., Ltd.]; “E1830”, “E5844” [Daikin Industries, Ltd.]; F-top “EF301”, “EF303”, “EF351” and “EF352” [Mitsubishi Materials Electronics Chemical Co., Ltd.] Is mentioned.

  When the leveling agent is contained in the composition for forming a polarizer, the content is usually 0.3 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the polymerizable liquid crystal compound, preferably 0.5 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 polarizer tends to be smoother. If the content of the leveling agent with respect to the polymerizable liquid crystal compound exceeds the above range, unevenness tends to occur in the obtained polarizer. In addition, the composition for polarizer formation may contain 2 or more types of leveling agents.

2. As the first base material 12 and the second base material 14, a thermoplastic resin base material can be used. The first substrate 12 and the second substrate 14 are preferably transparent thermoplastic resin substrates. The transparent thermoplastic resin base material is a thermoplastic resin base material having a transparency that can transmit light, particularly visible light. Transparency refers to the characteristic that the transmittance with respect to light rays over a wavelength range of 380 nm to 780 nm is 80% or more. The first substrate and the second substrate may be formed from the same thermoplastic resin, or may be formed from different thermoplastic resins.

  Specifically, as the first base material 12 and the second base material 14, for example, polyolefin such as polyethylene, polypropylene, norbornene-based polymer; cyclic olefin-based resin; polyvinyl alcohol; polyethylene terephthalate; Acrylic resins such as polyacrylic acid ester; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyetherketone; polyphenylene sulfide and polyphenylene oxide. Among them, from the viewpoint of being easily available from the market or having excellent transparency, a cyclic olefin resin, polyethylene terephthalate or acrylic resin is preferable, and a cyclic olefin resin or polymethacrylate is particularly preferable. It is. In the manufacturing process of the polarizing plate 1, the first base material 12 and the second base material 14 can be easily handled without causing breakage or the like when the first base material 12 and the second base material 14 are transported or stored. A support base material or the like may be attached to 12 and the second base material 14.

  If either one of the first substrate 12 and the second substrate 14 is a thermoplastic resin substrate, the other may not be a thermoplastic resin substrate. If either one of the first base material 12 and the second base material 14 is a thermoplastic resin base material, the curved surface moldability of the polarizing plate 1 is maintained. For example, a substrate containing a cellulose ester resin such as triacetyl cellulose, diacetyl cellulose, or cellulose acetate propionate may be used as the first substrate. As an example, a substrate containing triacetyl cellulose can be used as the first substrate, and a substrate containing an acrylic resin can be used as the second substrate.

  When the phase difference is imparted to the first substrate 12, a plastic substrate made of a cellulose ester or a cyclic olefin resin is preferable because the phase difference value can be easily controlled.

  In the cellulose ester, at least a part of the hydroxyl group contained in the cellulose is acetic esterified. A cellulose ester film comprising such a cellulose ester can be easily obtained from the market. Examples of commercially available triacetyl cellulose films include “Fujitac Film” (Fuji Photo Film Co., Ltd.); “KC8UX2M”, “KC8UY” and “KC4UY” (Konica Minolta Opto Co., Ltd.). Such a commercially available triacetyl cellulose film can be used as the first substrate 12 as it is or after being imparted with retardation as necessary. Further, after the surface of the prepared first substrate 12 is subjected to surface treatment such as anti-glare treatment, hard coat treatment, antistatic treatment or antireflection treatment, it can be used as the first substrate 12. .

  Cyclic olefin resin is comprised from the polymer or copolymer of cyclic olefins, such as norbornene and a polycyclic norbornene-type monomer, for example. The cyclic olefin-based resin may partially include a ring-opening portion, or may be a hydrogenated cyclic olefin-based resin including a ring-opening portion. The cyclic olefin resin is, for example, a copolymer of a cyclic olefin and a chain olefin or a vinylated aromatic compound (such as styrene) in that the transparency is not significantly impaired or the hygroscopicity is not significantly increased. May be. The cyclic olefin resin may have a polar group introduced into its molecule.

  When the cyclic olefin-based resin is a copolymer of a cyclic olefin and a chain olefin or an aromatic compound having a vinyl group, examples of the chain olefin include ethylene and propylene, and vinylated aromatic compounds. Examples include styrene, α-methylstyrene, and alkyl-substituted styrene. In such a copolymer, the content ratio of the structural unit derived from the cyclic olefin is 50 mol% or less, for example, in the range of about 15 mol% to 50 mol% with respect to all the structural units of the cyclic olefin resin. is there. When the cyclic olefin-based resin is a terpolymer obtained from a cyclic olefin, a chain olefin, and a vinylated aromatic compound, for example, the content ratio of the structural unit derived from the chain olefin is the cyclic olefin. The content ratio of the structural unit derived from the vinylated aromatic compound is about 5 mol% to 80 mol% with respect to all the structural units of the resin. Such a cyclic olefin resin of a terpolymer has an advantage that the amount of expensive cyclic olefin used can be relatively reduced when the cyclic olefin resin is produced.

  Cyclic olefin resin is easily available from the market. Examples of commercially available cyclic olefin resins include “Topas” [Ticona (Germany)]; “Arton” [JSR Corporation]; “ZEONOR” and “ZEONEX” [Nippon Zeon Corporation] )]; “Apel” [Mitsui Chemicals, Inc.]. Such a cyclic olefin-based resin can be formed into a film (cyclic olefin-based resin film) by, for example, known film-forming means such as a solvent casting method or a melt extrusion method. Moreover, the cyclic olefin resin film already marketed with the form of a film can also be used. Examples of such commercially available cyclic olefin resin films include “Essina” and “SCA40” [Sekisui Chemical Co., Ltd.]; “Zeonor Film” [Optes Corporation]; and “Arton Film” [JSR ( Co.)].

  The thickness of the first base material 12 and the second base material 14 is preferably thin, but is too thin in terms of weight that allows practical handling and sufficient transparency. However, the strength tends to decrease and the processability tends to be inferior. The appropriate thickness of each of the first base material 12 and the second base material 14 is, for example, about 20 μm to 200 μm, and preferably about 20 μm to 160 μm. When using the polarizing plate 1 of this embodiment as a circularly polarizing plate to be described later, or particularly when using it as a polarizing plate for mobile devices, the thickness of the transparent substrate is preferably about 20 μm to 80 μm, preferably 20 μm to 50 μm. There may be.

3. Alignment layer It is preferable that an alignment layer 22 is formed on the first substrate 12 or the second substrate 14. In this case, the composition for forming a polarizer is applied on the alignment layer 22. For this reason, it is preferable that the alignment layer 22 has a solvent resistance to such an extent that the alignment layer 22 does not dissolve when the polarizer-forming composition is applied. Moreover, it is preferable to have heat resistance in the heat treatment for removing the solvent and aligning the liquid crystal. The alignment layer 22 can be formed of an alignment polymer.

  Examples of the orientation polymer include polyamide, gelatin, polyimide, polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylic acid ester. be able to. Among these, polyvinyl alcohol is preferable. These orientation polymers may be used alone or in combination of two or more.

  The orientation polymer is applied onto the first substrate 12 or the second substrate 14 as an orientation polymer composition (solution containing the orientation polymer) dissolved in a solvent, whereby the first substrate 12 is coated. Alternatively, the alignment layer 22 can be formed on the second substrate 14. Examples of the solvent include water; alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, and γ-butyrolactone. Ester solvents such as propylene glycol methyl ether acetate and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; toluene And aromatic hydrocarbon solvents such as xylene, nitrile solvents such as acetonitrile; tetrahydrofuran and dimethoxyethylene Ether solvents emissions and the like; as well as chloroform and chlorinated hydrocarbon solvents such as chlorobenzene. These solvents may be used alone or in combination of two or more.

  A commercially available alignment film material may be used as it is as the alignment polymer composition. Examples of commercially available alignment film materials include Sunever (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) and Optmer (registered trademark, manufactured by JSR Corporation).

  The alignment layer 22 may be a photo-alignment layer. With the photo-alignment layer, a composition containing a polymer or monomer having a photoreactive group and a solvent (hereinafter sometimes referred to as “photo-alignment layer forming composition”) is applied to the first substrate 12, It refers to an alignment layer imparted with alignment regulating force by irradiation with polarized light (preferably polarized UV). The photoreactive group refers to a group that generates liquid crystal alignment ability when irradiated with light. Specifically, the photoreactive group is the origin of liquid crystal alignment ability such as molecular orientation induction or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photolysis reaction caused by light irradiation. Causes a photoreaction. A photoreactive group that causes a dimerization reaction or a photocrosslinking reaction is preferable in that it has excellent orientation and maintains a smectic liquid crystal state during polarizer formation. As the photoreactive group, those having an unsaturated bond, particularly a double bond are preferred, and a carbon-carbon double bond (C = C bond), a carbon-nitrogen double bond (C = N bond), and nitrogen-nitrogen. A group having at least one selected from the group consisting of a double bond (N═N bond) and a carbon-oxygen double bond (C═O bond) is more preferable.

  Examples of the photoreactive group having a C═C bond include a vinyl group, a polyene group, a stilbene group, a stilbazole group, a stilbazolium group, a chalcone group, and a cinnamoyl group. Examples of the photoreactive group having a C═N bond include groups having a structure such as an aromatic Schiff base and an aromatic hydrazone. Examples of the photoreactive group having an N═N bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and a group having a basic structure of azoxybenzene. Examples of the photoreactive group having a C═O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have a substituent such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, or a halogenated alkyl group. Among them, a photoreactive group capable of causing a photodimerization reaction is preferable, and a cinnamoyl group and a chalcone group have a relatively small amount of polarized light irradiation necessary for photoalignment, and a photoalignment layer having excellent thermal stability and temporal stability. Since it is easy to obtain, it is preferable. Furthermore, as a polymer which has a photoreactive group, what has a cinnamoyl group in which the terminal part of a polymer side chain becomes a cinnamic acid structure is more preferable.

  As a solvent for the composition for forming a photo-alignment layer, a solvent that dissolves a polymer and a monomer having a photoreactive group is preferable, and examples thereof include the solvent used in the above-described aligning polymer composition.

  The concentration of the polymer or monomer having a photoreactive group with respect to the composition for forming a photoalignment layer can be appropriately adjusted depending on the type of polymer or monomer having a photoreactive group and the thickness of the photoalignment layer to be produced. Expressed in terms of partial concentration, it is preferably at least 0.2% by mass, and more preferably in the range of 0.3% by mass to 10% by mass. As long as the properties of the alignment layer 22 are not significantly impaired, the composition for forming a photo-alignment layer may contain a polymer material such as polyvinyl alcohol and polyimide, and a photosensitizer.

  The thickness of the alignment layer 22 is 10 nm or more and 10000 nm or less, preferably 10 nm or more and 1000 nm or less. The thickness of the alignment layer 22 in the present embodiment can be obtained by measuring any five points of the alignment layer 22 with an interference film thickness meter and calculating an average value thereof.

  In the polarizer 11 according to this embodiment, the absorbance (A1) in the absorption axis direction at a wavelength of 380 nm to 760 nm is 0.3 or more and 1.5 or less, preferably 0.3 or more and 1.0 or less. More preferably, it is 0.33 or more and 0.9 or less, and further preferably 0.36 or more and 0.85 or less. The absorbance (A2) in the direction of the transmission axis is 0.001 or more and 0.15 or less, preferably 0.001 or more and 0.10 or less, more preferably 0.002 or more and 0.05 or less, More preferably, it is 0.005 or more and 0.040 or less.

  The absorbance is determined by adjusting the thickness of the polarizer 11 by adjusting the type of the dichroic dye 102 contained in the polarizer 11, the amount of the dichroic dye 102, the solid content concentration of the composition for forming the polarizer, or the coating amount. It can adjust suitably by controlling this.

4). Manufacturing method of polarizing plate The method to manufacture the polarizing plate 1 using the composition for polarizer formation is demonstrated. In such a method, the polarizing plate 1 is formed by applying the composition for forming a polarizer to the first substrate 12, preferably the first substrate 12 which is preferably a transparent thermoplastic resin substrate. In the present embodiment, an example in which the cured product 101 of the liquid crystal compound is a polymerizable liquid crystal compound will be described.

  Examples of the method for forming the alignment layer 22 on the first substrate 12 include a method in which an alignment layer forming composition or a commercially available alignment film material is applied on the first substrate 12 and heated. The thickness of the coating film of the composition for forming an alignment layer is determined in consideration of the thickness of the alignment layer 22 to be obtained.

  In order to impart an alignment regulating force to the alignment layer 22, it is preferable to perform rubbing as necessary (rubbing method). By applying the alignment regulating force, the cured product 101 of the liquid crystal compound can be aligned in a desired direction.

  As a method of applying an alignment regulating force by the rubbing method, for example, a rubbing cloth is wound, a rotating rubbing roll is prepared, and a coating film for forming an alignment layer is formed on the first substrate 12. The laminated body is placed on a stage and conveyed toward a rotating rubbing roll, whereby the alignment layer forming coating film and the rotating rubbing roll are brought into contact with each other.

  Examples of the method for applying the alignment layer forming composition or the photo alignment layer forming composition on the first substrate 12 include a spin coating method, an extrusion method, a gravure coating method, a die coating method, a bar coating method, and the like. A known method such as a coating method such as an applicator method or a printing method such as a flexo method is employed. When the polarizer is manufactured by a roll-to-roll continuous manufacturing method, a printing method such as a gravure coating method, a die coating method, or a flexo method is usually employed as the coating method.

  Note that a plurality of regions (patterns) having different orientation directions can be formed by performing masking when performing rubbing or polarized light irradiation.

  On the first substrate 12 or the alignment layer 22 formed on the first substrate 12, a composition for forming a polarizer is applied to obtain a coating film. Examples of the method for applying the composition for forming a polarizer include the same methods as those exemplified as the method for applying the alignment layer-forming composition or the photo-alignment layer-forming composition to a substrate.

  Next, a dry film is formed by drying and removing the solvent contained in the polarizer-forming composition under the condition that the liquid crystal compound contained in the coating film is not polymerized. Examples of the drying method include natural drying, ventilation drying, heat drying, and reduced pressure drying.

  As a preferred form, once the liquid crystal state of the liquid crystal compound contained in the dry film is changed to a nematic liquid crystal, the nematic liquid crystal phase is changed to a smectic liquid crystal phase. In order to form a smectic liquid crystal phase via the nematic liquid crystal phase in this way, for example, the liquid crystal compound contained in the dry film is heated to a temperature at which the nematic liquid crystal phase is exhibited or higher, and then the liquid crystal compound exhibits a smectic liquid crystal phase. A method of cooling to the indicated temperature is employed.

  When the liquid crystal compound in the dry film is made into a smectic liquid crystal phase, or the polymerizable liquid crystal compound is made into a smectic liquid crystal phase via a nematic liquid crystal phase, the liquid crystal state is measured by measuring the phase transition temperature of the polymerizable liquid crystal compound. It is possible to obtain the conditions (heating conditions) for controlling.

  Next, the polymerization process of the liquid crystal compound will be described. Here, a photopolymerization initiator is contained in the composition for forming a polarizer, and after the liquid crystal state of the liquid crystal compound in the dry film is changed to a smectic liquid crystal phase, the liquid crystal compound is maintained while maintaining the liquid crystal state of the smectic liquid crystal phase. The photopolymerization method will be described in detail.

  In the photopolymerization, the light applied to the dry film is appropriately selected according to the type of photopolymerization initiator contained in the dry film or the type of liquid crystal compound (particularly, the type of polymerizable group possessed by the liquid crystal compound) and the amount thereof. , Light selected from the group consisting of visible light, ultraviolet light and laser light, or an active electron beam. Among these, ultraviolet light is preferable in that it is easy to control the progress of the polymerization reaction and that apparatuses widely used in the field as photopolymerization apparatuses can be used. Therefore, it is preferable to select the type of liquid crystal compound or photopolymerization initiator contained in the composition for forming a polarizer so that photopolymerization can be performed with ultraviolet light.

  Moreover, when superposing | polymerizing, superposition | polymerization temperature can also be controlled by cooling a dry film with a suitable cooling means with ultraviolet light irradiation. If the liquid crystal compound can be polymerized at a lower temperature by employing such a cooling means, the polarizer 11 can be appropriately formed even if a substrate having relatively low heat resistance is used as the first substrate 12. There are also advantages. In addition, the patterned polarizer 11 can also be obtained by performing a masking and image development at the time of photopolymerization.

  By performing the photopolymerization as described above, the liquid crystal compound is polymerized while maintaining the nematic liquid crystal phase or the smectic liquid crystal phase, preferably the higher-order smectic liquid crystal phase as exemplified above, and the polarizer 11 is formed. The A polarizer 11 obtained by polymerizing a liquid crystal compound while maintaining a smectic liquid crystal phase has a polarization performance as compared with a polarizer obtained by polymerizing a polymerizable liquid crystal compound or the like while maintaining a liquid crystal state of a nematic liquid crystal phase. There is an advantage that is high. Furthermore, there is an advantage that the strength is excellent as compared with the case where only the lyotropic dichroic dye is applied.

  The thickness of the polarizing layer 21 is preferably 1 μm or more and less than 15 μm, more preferably 1 μm or more and 10 μm or less, further preferably 1 μm or more and 5 μm or less, and particularly preferably 1 μm or more and 3 μm or less. Therefore, the thickness of the coating film for forming the polarizer is determined in consideration of the thickness of the obtained polarizing layer 21. In the present embodiment, the thickness of the polarizing layer 21 is determined by measuring any five points of the polarizing layer 21 with a contact-type film thickness meter, an interference film thickness meter, a laser microscope or a stylus-type film thickness meter. It can be obtained by calculating.

  In addition to the method of forming the polarizer 11 on the first substrate 12 as described above, after forming the polarizer 11 on the other substrate by the method described above, the polarizer 11 is A polarizing plate can also be manufactured by the method of transferring and bonding to the base material 12.

  In the above example, the example in which the alignment layer 22 and the polarizing layer 21 are formed on the first substrate 12 has been described, but the alignment layer 22 and the polarizing layer 21 may be formed on the second substrate 14. Good. In this case, by laminating the first substrate 12 on the polarizing layer 21 via an adhesive layer or a pressure-sensitive adhesive layer, the second substrate 14, the alignment layer 22, the polarizing layer 21, and the first substrate are stacked. A polarizing plate having a material is obtained.

  It is preferable that the formed polarizer 11 has a Bragg peak in X-ray diffraction measurement. Examples of the polarizer from which the Bragg peak can be obtained include a polarizer showing a diffraction peak derived from a hexatic phase or a crystal phase.

  When manufacturing a polarizer commercially, a method capable of continuously forming a polarizer is required. Such a continuous manufacturing method is based on the Roll to Roll format, and is sometimes referred to as “the present manufacturing method”. In addition, in this manufacturing method, it demonstrates centering around the case where the 1st base material 12 is transparent. When the first substrate 12 is transparent, what is finally obtained is the polarizing plate 1 having the transparent first substrate 12 and the polarizer 11.

  This manufacturing method includes the following processes, for example. A first roll in which the first base 12 is wound around a first core is prepared. The 1st base material 12 is sent out continuously from the 1st roll. An alignment layer 22 is continuously formed on the first substrate 12. A composition for forming a polarizer is continuously applied on the alignment layer 22. A dried film is continuously formed on the alignment layer 22 by drying the applied composition for forming a polarizer under conditions in which the liquid crystal compound is not polymerized. The liquid crystal compound contained in the dry film is a nematic liquid crystal phase, preferably a smectic liquid crystal phase. Thereafter, the liquid crystal compound is polymerized while maintaining the smectic liquid crystal phase, whereby the polarizing layer 21 is continuously obtained to obtain the polarizer 11. The polarizer 11 obtained continuously is wound around a second winding core to obtain a second roll.

  The polarizing plate 1 obtained by this production method is a polarizing film having a film shape and a long shape. When the polarizing plate 1 is used for a lens such as sunglasses described later, the polarizing plate 1 is used after being cut according to the size of the lens such as sunglasses.

  The polarizing plate 1 can take the form of a laminate of the first substrate 12 / alignment layer 22 / polarizing layer 21. Furthermore, the polarizing plate 1 may have a form in which a layer or a film other than the first base material 12 / alignment layer 22 / polarizing layer 21 is further laminated. As these layers and films, a retardation film may be further provided in the polarizing plate 1, or an antireflection layer or a brightness enhancement film may be further provided.

  For example, the polarizing plate 1 of this embodiment becomes the circularly polarizing plate 2 by further including a quarter wavelength plate. FIG. 3 is a schematic cross-sectional view of a circularly polarizing plate in one embodiment of the present invention. The circularly polarizing plate 2 is disposed on the other surface of the first substrate 12, the first substrate 12 having the alignment layer 22 disposed on one surface, the polarizing layer 21 provided on the alignment layer 22, and the first substrate 12. And a retardation film 15 which is a quarter wavelength plate. Further, the retardation film 15 may be positioned on the second surface 32 of the polarizer 11. In this case, as shown in FIG. 4, the circularly polarizing plate 2 ′ can take a form in which the first base material 12, the alignment layer 22, the polarizing layer 21, and the retardation film 15 are arranged in this order.

  When producing a circularly-polarizing plate, even if the 1st base material 12 or the polarizer 11, and the phase difference film 15 are bonded through the adhesion layer formed from an adhesive using a suitable adhesive. Good.

  By using the 1st base material 12 to which phase difference was previously given, 1st base material 12 itself may have the function as a phase difference layer. By using the first substrate 12 itself as a retardation film, a circularly polarizing plate or an elliptically polarizing plate in the form of the first substrate 12 / alignment layer 22 / polarizing layer 21 can be used. Thus, it is preferable that the quarter wavelength plate used when manufacturing the circularly polarizing plate has a characteristic that the in-plane retardation value with respect to visible light becomes smaller as the wavelength becomes shorter.

  Using a half-wave plate as the retardation film 15, a linear polarizing plate roll as set by shifting the angle between the slow axis and the absorption axis of the polarizer 11 was prepared, and the surface on which the polarizer 11 was formed It is possible to form a broadband circularly polarizing plate by further forming a quarter wavelength plate on the opposite side.

The birefringence with respect to light having a wavelength of 450 nm, the birefringence with respect to light having a wavelength of 550 nm, and the birefringence with respect to light having a wavelength of 650 nm of the quarter wavelength plate used as the retardation film 15 are represented by the following formulas (II) and (III) It is preferable to have reverse wavelength dispersion satisfying the relationship represented by In the formula, Δn (λ) represents a birefringence for light having a wavelength of λ nm.
Δn (450) / Δn (550) ≦ 1.00 (II)
1.00 ≦ Δn (650) / Δn (550) (III)
A retardation film exhibiting such reverse wavelength dispersion characteristics can be produced by the method described in Japanese Patent No. 5463666.

  Examples of the method for forming the curved portion by heating the polarizing plate 1 of the present embodiment include insert molding, injection molding, pressure molding, vacuum molding, and die press.

  The polarizing plate 1 in the present embodiment has a curved portion with a small radius of curvature because the thermal contraction is small and thin.

  As one aspect of the present invention, the first substrate 12 is preferably an acrylic resin film or a cyclic olefin resin film. When these thermoplastic resin base materials are used, the polarizing plate 1 having a curved portion with a small curvature radius can be realized because it is easy to process at a low temperature and has good thermoformability.

  As one aspect of the present invention, the liquid crystal compound is preferably a compound represented by the following formula (4-6) or a compound represented by the formula (4-7).

  As one aspect of the present invention, the dichroic dye 102 is selected from the group consisting of a compound represented by formula (2-15), a compound formula represented by formula (2-18), and formula (2-37). It is preferable to include at least one selected. The compound represented by the formula (2-15) has a maximum absorption wavelength at 380 nm. The compound represented by the formula (2-18) has a maximum absorption wavelength at 490 nm. The compound represented by the formula (2-37) has a maximum absorption wavelength at 590 nm. When these dichroic dyes are used, a polarizing plate having high polarization characteristics can be realized. The dichroic dye 102 more preferably includes a compound represented by the formula (2-15), a compound formula represented by the formula (2-18), and a formula (2-37).

  As one aspect of the present invention, the polarizing plate 1 includes an acrylic resin film as the first thermoplastic resin substrate (first substrate 12), and is represented by the formula (4-6) as a liquid crystal compound. A compound represented by formula (2-15), a compound represented by formula (2-18), and a compound represented by formula (2- Those containing the compound represented by 37) are preferred. In such a polarizing plate 1, since it is not necessary to provide a 2nd base material and a thinner polarizing plate can be implement | achieved, the polarizing plate which has a curved part with a small curvature radius is realizable.

  As one aspect of the present invention, the polarizing plate 1 includes a first thermoplastic resin substrate (first substrate 12) having a thickness of 20 μm to 200 μm, a polarizing layer 21 having a thickness of 1 μm to 5 μm, and an alignment layer. The thickness of 22 is preferably 10 nm to 1000 nm. In such a polarizing plate 1, since a thinner polarizing plate can be realized, a polarizing plate having a curved portion with a small radius of curvature can be realized.

Second Embodiment
The polarizing plate according to the second embodiment of the present invention is different from the first embodiment in that the polarizer has a polarizing layer in which iodine or a dichroic dye is oriented on a PVA film. Moreover, since the polarizing layer does not contain the liquid crystal compound, the polarizer in this embodiment does not need to have an alignment layer. That is, the polarizer of this embodiment may have only a polarizing layer. The configuration other than the polarizer of the present embodiment is the same as that of the first embodiment.

  Specific examples of the polarizing layer of the present embodiment include a polarizing layer in which iodine is adsorbed on the PVA film, a polarizing layer in which dichroic dye is adsorbed and oriented on the PVA film, and a modification containing a cationic group in the molecule. Examples include a polarizing layer having a dichroic dye on at least one of the surface and the inside of the PVA film. In addition, as a dichroic dye, the above-mentioned dichroic dye can be used.

  By making the thickness of a polarizer having a polarizing layer in which iodine or a dichroic dye is oriented on a PVA film to be 15 μm or less, the shape change can be reduced even when placed in a high temperature environment after curved surface molding. Can do.

  In the case of a polarizing layer in which iodine is oriented on the PVA film, the moisture content of the PVA film is usually 5 to 20% by weight, and preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizing layer is lost, and the polarizing layer may be damaged or broken after drying. On the other hand, when the moisture content exceeds 20% by weight, the thermal stability of the polarizing layer may be inferior.

  As a base material laminated | stacked with the polarizer in this embodiment, the 1st base material and 2nd base material which are described in 1st Embodiment can be used. Since the polarizer in this embodiment has a thickness of 15 μm or less, the shape change is small even when it is placed in a high temperature environment after being curved.

  As for the polarizing plate of this embodiment, only the 1st base material may be laminated | stacked on the polarizer similarly to 1st Embodiment. As in the first embodiment, the polarizing plate includes a polarizer, a first substrate positioned on the first surface of the polarizer, and a second substrate positioned on the second surface of the polarizer. May be included.

  The method for producing such a polarizing layer is not particularly limited. For example, after stretching the PVA film, a method of adsorbing iodine ions to the PVA film, a method of stretching the PVA film after dyeing with a dichroic dye, Known methods such as a method of dyeing a PVA film with a dichroic dye after stretching, a method of stretching a dichroic dye after printing on a PVA film, and a method of printing a dichroic dye after stretching a PVA film are included. . In order to make the thickness of the polarizing layer 15 μm or less, it is preferable to use a PVA film before stretching that has a thickness of 30 μm or less.

  For example, iodine is dissolved in a potassium iodide solution to prepare higher-order iodine ions, and after the iodine ions are adsorbed on a PVA film and stretched, a bath temperature of 30 to 40 ° C. is added to a 1 to 4 wt% boric acid aqueous solution. And a method of producing a polarizing layer by immersing in the above. Alternatively, the PVA film is similarly treated with boric acid, stretched about 3 to 7 times in a uniaxial direction, and immersed in a 0.05 to 5% by weight dichroic dye aqueous solution at a bath temperature of 30 to 40 ° C. to adsorb the dye. And a method of producing a polarizing layer by drying at 80 to 100 ° C. and heat setting.

  Moreover, also in the case of the polarizer of this embodiment, it can use as a circularly-polarizing plate by further providing a quarter wavelength plate.

  Examples of the method for forming the curved portion by heating the polarizing plate having the polarizer of the present embodiment include insert molding, injection molding, pressure molding, vacuum molding, mold press and the like as in the above-described method.

  Since the polarizer in the present embodiment has a polarizer thickness of 15 μm or less, the thermal shrinkage is smaller than that of a conventional polarizer including a stretched PVA having a thickness of 20 μm to 30 μm as a polarizer. Moreover, the polarizing plate in this embodiment can have a curved part with a small curvature radius.

<Use of polarizing plate>
The polarizing plate or the circularly polarizing plate in the present embodiment can be used for various articles having a curved portion. For example, it can be used for a lens for sunglasses, a goggle lens for a three-dimensional image display device, and the like. Since the polarizing plate or circularly polarizing plate in this embodiment can paste a polarizing plate or a circularly polarizing plate on a curved surface with a small curvature radius, it contributes to an improvement in design property.

  The polarizing plate in this embodiment can be used for various display devices having a curved display surface. A display device is a device having a display element and includes a light-emitting element or a light-emitting device as a light-emitting source. Examples of the display device include a liquid crystal display device, an organic electroluminescence (EL) display device, an inorganic electroluminescence (EL) display device, an electron emission display device (for example, a field emission display device (FED), a surface field emission display device (SED). )), Electronic paper (display device using electronic ink or electrophoretic element, plasma display device, projection display device (eg, display device having a grating light valve (GLV) display device, digital micromirror device (DMD)), Examples include a piezoelectric ceramic display.

  Examples of the liquid crystal display device include a transmissive liquid crystal display device, a transflective liquid crystal display device, and a reflective liquid crystal display device. These display devices may be a display device that displays a two-dimensional image, or may be a stereoscopic display device that displays a three-dimensional image.

  The polarizing plate of this embodiment can be effectively used particularly for a display device of an organic EL display device or an inorganic EL display device. Since the polarizing plate or the circularly polarizing plate in the present embodiment can be bonded to a curved surface having a small curvature radius, the aspect even when the display device has a curved portion at the end or corner. A polarizing plate or a circularly polarizing plate can be bonded so as to cover the surface, which contributes to improvement in design.

  Electronic paper includes those displayed by molecules such as optical anisotropy and dye molecule orientation, those displayed by particles such as electrophoresis, particle movement, particle rotation, and phase change, and one end of the film moves. And the like, those displayed by molecular color development / phase change, those displayed by light absorption of molecules, and those displayed by self-emission by combining electrons and holes.

  More specifically, microcapsule type electrophoresis, horizontal movement type electrophoresis, vertical movement type electrophoresis, spherical twist ball, magnetic twist ball, cylindrical twist ball method, charged toner, electronic powder fluid, magnetophoretic type, magnetic thermosensitive Formula, electrowetting, light scattering (transparency / transparency change), cholesteric liquid crystal / photoconductive layer, cholesteric liquid crystal, bistable nematic liquid crystal, ferroelectric liquid crystal, dichroic dye / liquid crystal dispersion type, movable film, leuco dye And color erasing, photochromic, electrochromic, electrodeposition, flexible organic EL, and the like. The electronic paper may be used not only for personal use of text and images but also for advertisement display (signage) or the like. According to the polarizing plate or the circularly polarizing plate of this embodiment, the thickness of the electronic paper can be reduced.

  As a stereoscopic display device, for example, a method of arranging different retardation films alternately like a micropole method has been proposed (Japanese Patent Laid-Open No. 2002-185983). However, when the polarizing plate of this embodiment is used, printing is performed. Since patterning is easy by inkjet, photolithography, etc., the manufacturing process of the display device can be shortened, and a retardation film is not required.

  The polarizing plate and the circularly polarizing plate in the present embodiment can be used particularly for a display device having a curved portion with a small curvature radius. Specifically, a polarizing plate can be bonded to a smartphone having a curved portion at the edge or corner of the screen. Further, the polarizing plate and the circularly polarizing plate of the present embodiment can be used for a VR (virtual reality) head mounted display.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely using an Example, this invention is not limited by an Example.

[Evaluation of curved surface formability]
The curved surface of the polarizing plate was molded as follows. A polarizing plate was sandwiched between two metal plates having a 10 cm diameter hole in the center. The polarizing plate was heated to 100 ° C. to 140 ° C. using a heat gun. A cylindrical glass having an arbitrary radius of curvature was pressed against the heated polarizing plate to form a curved surface. The curvature radius of the polarizing plate was calculated from the diameter of the curved portion and the arrow height.
The evaluation of the curved formability is carried out by visual inspection, and when the curved surface is formed and no defects such as cracks occur in the substrate or the polarizer, it is judged that the curved formability is good. Rated as bad.

(Measurement of polarizer thickness)
The arbitrary 5 points | pieces of a polarizer were measured using the contact-type film thickness meter (digital micrometer MH-15M; Nikon Corporation make), and the thickness of the polarizer was calculated | required by calculating the average value.

[Evaluation of shape change under high temperature environment]
The polarizing plate having a curved surface formed by the above method was put into an oven at 60 ° C. or 80 ° C. for 24 hours. Then, the shape change was evaluated using a ruler. It was judged that the dimensions such as the radius of curvature and the height were good when they were maintained in the state before being put into the oven, and it was judged as bad when they were not.

[Example 1]
[Preparation of a composition for forming a polarizer]
The following polymerizable liquid crystal compound, dichroic dye, polymerization initiator, leveling material and solvent were mixed in the following ratio. The obtained mixture was stirred at 80 ° C. for 1 hour to obtain a composition for forming a polarizer. The dichroic dye was synthesized in the same manner as the compound described in JP2013-101328A.

(Polymerizable liquid crystal compound)
As the polymerizable liquid crystal compound, 75 parts by mass of the compound represented by the formula (4-6) and 25 parts by mass of the compound represented by the formula (4-7) were used.

(Dichroic dye)
As a dichroic dye, 2.6 parts by mass of a compound represented by the formula (2-15) (having a maximum absorption wavelength at 380 nm) and a compound represented by the formula (2-18) (maximum absorption wavelength at 490 nm) 2.6 parts by mass, and a compound represented by the formula (2-37) (having a maximum absorption wavelength at 590 nm) was used at 2.2 parts by mass.

(Other ingredients)
As a polymerization initiator, 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one (Irgacure 369; manufactured by Ciba Specialty Chemicals) was used in an amount of 6 parts by mass.
As a leveling agent, a polyacrylate compound (BYK-361N; manufactured by BYK-Chemie) was used at 1.2 parts by mass.
As a solvent, o-xylene was used at 250 parts by mass.

[Production method of polarizing plate]
A roll of triacetyl cellulose (TAC) film (Konica Minolta Co., Ltd., KC4UY-TAC, thickness 40 μm) as the second substrate is continuously unwound at a speed of 10 m / min, and photo-alignment is performed by a slot die coater. The layer forming composition was discharged to form a first coating film. Furthermore, the solvent was removed by carrying for 2 minutes in the ventilation drying furnace set to 120 degreeC, and the 1st dry film | membrane was formed.

Thereafter, polarized UV light polarized in the direction of 0 ° with respect to the film transport direction is applied to the first dry film so as to have an intensity of 50 mJ / cm ² (reference to 313 nm). A substrate film with an alignment layer was produced. On the surface of the photo-alignment layer, the composition for forming a polarizer was applied by a slot die coater to form a second coating film. Furthermore, the solvent was removed by carrying it in the ventilation drying furnace set to 120 degreeC for 2 minutes, and the 2nd dry film | membrane was formed.

Thereafter, UV light was irradiated at 50 mJ / cm ² (365 nm standard) to polymerize and cure the polymerizable liquid crystal compound, thereby forming a polarizer. Thereafter, an acrylic resin film (S001G, manufactured by Sumitomo Chemical Co., Ltd.), which is the first base material, is laminated on the polarizer via an ultraviolet curable adhesive, and continuously rolled up to form a 0 ° direction. A polarizing film roll having an absorption axis was prepared.

  Various evaluations were performed using the polarizing plate rolls produced in this manner and cut into 10 cm square sizes as polarizing plates. The thickness of the alignment layer of the produced polarizing plate was 100 nm, and the thickness of the polarizing layer was 2 μm. The thickness of the alignment layer and the polarizing layer was determined by measuring an arbitrary five points of each layer with an interference film thickness meter, a laser microscope or a stylus thickness meter, and calculating an average value thereof. Table 1 shows the evaluation results of the curved surface moldability of the polarizing plate and the evaluation results of the shape change under a high temperature environment.

(Examples 2 to 5, Comparative Example 1)
The polarizing plates of Examples 2 to 5 and Comparative Example 1 were prepared in the same procedure as in Example 1 except that the first and second base materials and curved surface molding were changed as shown in Table 1. In Examples 4 and 5 and Comparative Example 1, the polarizing plate was not provided with the second base material. In addition, COP in Table 1 indicates a cyclic olefin-based resin film (manufactured by Nippon Zeon Co., Ltd.).

(Example 6)
The polarizing plate of Example 6 was produced as follows. A polarizer (manufactured by Sumitomo Chemical Co., Ltd.) in which stretched PVA was dyed with iodine was bonded onto an acrylic resin (manufactured by Kaneka Corporation) as the first base material. A TAC film was bonded to the other surface of the polarizer via an adhesive. The water content of this polarizer was 10% by weight.

(Examples 7 to 10, Comparative Example 2)
The polarizing plates of Examples 7 to 10 and Comparative Example 2 were produced in the same procedure as Example 6 except that the first and second substrates were changed as shown in Table 1. In Examples 9 and 10, and Comparative Example 2, the second substrate was not provided on the polarizing plate.

  The polarizing plates of Examples 1 to 5 were excellent in curved surface moldability, and no change in shape was observed even at 60 ° C. and 80 ° C. environment. The polarizing plates of Examples 6 to 10 were excellent in curved surface moldability, and no change in shape was observed under an environment of 60 ° C. However, a shape change occurred under an environment of 80 ° C. This is probably because stretched PVA contracted in the stretching direction at 80 ° C. In Comparative Examples 1 and 2 in which a triacetyl cellulose film was used as the first base material and the second base material was not provided, the curved surface moldability was poor. Therefore, the shape change under high temperature environment could not be evaluated.

  The polarizing plate of the present invention is suppressed from shrinkage due to thermoforming, and can be bonded to an object having a curved portion with a small curvature radius.

  DESCRIPTION OF SYMBOLS 1,1 '... Polarizing plate, 2,2' ... Circular polarizing plate, 11 ... Polarizer, 12 ... 1st base material, 13 ... Curved part, 14 ... 1st 2 substrate, 15 ... retardation film, 101 ... cured product of liquid crystal compound, 102 ... dichroic dye, 21 ... polarizing layer, 22 ... orientation layer

Claims (8)

A polarizing plate having a polarizer having a first surface and a second surface, and a first substrate disposed on the first surface of the polarizer,
The polarizer has a thickness of 15 μm or less,
The first substrate is a thermoplastic resin substrate;
The polarizing plate in which the polarizing plate has at least one curved portion.   The polarizing plate according to claim 1, wherein a radius of curvature of the curved portion is 30 mm to 150 mm.   The polarizing plate according to claim 1, wherein the first base material contains at least one resin of an acrylic resin and a cyclic olefin resin. The polarizer includes a polarizing layer,
The polarizing layer includes a cured product of a liquid crystal compound and a dichroic dye,
The polarizing plate according to claim 1, wherein the dichroic dye is dispersed and oriented in the polarizing layer.   The polarizing plate according to claim 1, wherein the first substrate has a thickness of 40 μm to 120 μm.   Furthermore, the polarizing plate as described in any one of Claims 1-5 which has a 2nd base material on the said 2nd surface of the said polarizer.   The polarizing plate according to claim 6, wherein the second base material includes at least one selected from an acrylic resin, a cyclic olefin resin, and a triacetyl cellulose resin. The said polarizing plate is bonded and used for the said display surface of the display apparatus which has a curved surface on a display surface, The said curved part corresponds to the said curved surface. Polarizer.

Images