TWI908713B - Polarizing film and its manufacturing method - Google Patents

Abstract

This invention relates to a polarizing film having a liquid crystal curing layer. The liquid crystal curing layer comprises a liquid crystal compound and has at least a first region and a second region with different values of visual sensitivity correction transmittance. The second region has a higher visual sensitivity correction transmittance than the first region. Its top-view shape is circular, elliptical, oval, or polygonal. When the second region is circular, its diameter is 2 cm or less. When the second region is elliptical or oval, its major diameter is 2 cm or less. When the second region is polygonal, the diameter of the imaginary circle drawn inscribed in the polygon is 2 cm or less.

Description

Polarizing film and its manufacturing method

This invention relates to a polarizing film and a method for manufacturing the same.

Organic light-emitting diode (OLED) displays, or organic EL (electroluminescence) displays, offer advantages over liquid crystal displays (LCDs) in terms of weight reduction and thinness. They also provide a wider viewing angle, faster response time, and higher contrast, resulting in superior image quality. Consequently, they are widely used in smartphones, televisions, digital cameras, and other applications. In OLED displays, circular polarizers are used to enhance anti-reflective properties and suppress the reduction in visibility caused by reflections of external light.

As polarizing films used in such circular polarizers, Patents 1 and 2 describe patterned polarizing films obtained by depositing a patterned liquid crystal curing layer onto a substrate. In recent years, for the design of smartphones, there has been a demand for patterned polarizing films with areas of high visual sensitivity correction transmittance. However, if the areas of high visual sensitivity correction transmittance in a patterned polarizing film are large, it may result in poor polarization performance. Therefore, there is a need for patterned polarizing films with narrower areas of high visual sensitivity correction transmittance. [Prior Art Documents] [Patents]

[Patent Document 1] Japanese Patent Application Publication No. 2015-206852 [Patent Document 2] Japanese Patent Application Publication No. 2015-212823

[The problem that the invention aims to solve]

However, for patterned polarizing films with higher visual sensitivity correction and narrower areas, the following situation exists: wrinkles are generated in the film during pattern formation, resulting in a deterioration in the appearance of the film.

The purpose of this invention is to provide a polarizing film with high visual sensitivity correction, narrow transmission area, and excellent appearance, as well as a method for manufacturing the same. [Technical Means for Solving the Problem]

The present invention provides a polarizing film as shown below and a method for manufacturing the same. [1] A polarizing film having a liquid crystal curing layer, the liquid crystal curing layer comprising a liquid crystal compound, having at least a first region and a second region having different values of visual sensitivity correction transmittance, and the second region having a higher visual sensitivity correction transmittance than the first region, and having a top-view shape that is circular, elliptical, oval, or polygonal, wherein the diameter of the second region is 2 cm or less when it is circular, the major diameter of the second region is 2 cm or less when it is elliptical or oval, and the diameter of an imaginary circle drawn inscribed in the second region is 2 cm or less when the second region is polygonal. [2] A polarizing film as described in [1], further comprising a substrate layer and an alignment layer deposited on at least one side of the substrate layer, wherein a liquid crystal curing layer is deposited on the alignment layer. [3] A polarizing film as described in [2], wherein the alignment layer comprises a photoaligning polymer. [4] A polarizing film as described in any one of [1] to [3], wherein the liquid crystal compound comprises a polymerizable liquid crystal compound. [5] A polarizing film as described in any one of [1] to [4], wherein the visual sensitivity correction polarization value of the first region is higher than that of the second region. [6] A polarizing film as described in any one of [1] to [5], wherein the visual sensitivity correction polarization value in the first region is 90% or more. [7] A polarizing film of any one of [1] to [6], wherein the sensitivity-correcting polarization in the second region is 10% or less. [8] A polarizing film of any one of [1] to [7], wherein the liquid crystal curing layer further contains a dichroic pigment. [9] A polarizing film of [8], wherein the content of the dichroic pigment in the first region is greater than that in the second region. [10] A polarizing film of any one of [1] to [9], wherein the sensitivity-correcting monomer transmittance in the first region is 35% or more. [11] A polarizing film of any one of [1] to [10], wherein the sensitivity-correcting monomer transmittance in the second region is 80% or more. [12] A polarizing film of any one of [1] to [11], wherein the first region exhibits a Bühler peak in X-ray diffraction measurements. [13] A polarizing film of any one of [2] to [12], wherein the substrate layer has a quarter-wavelength plate function. [14] A polarizing film of any one of [1] to [13], wherein the length of the polarizing film is 10 m or more. [15] A circular polarizer, which is formed by laminating a polarizing film of any one of [1] to [12] and [14] and a phase détramorphic layer having a quarter-wavelength plate function. [16] A method for manufacturing a polarizing film, wherein the polarizing film has a lower content of dichroic pigment in a certain region of a liquid crystal curing layer than in other regions, the method comprising the step of irradiating a laminated film having the liquid crystal curing layer and a substrate layer containing dichroic pigment with a laser of wavelength from 300 nm to 800 nm. [17] The method for manufacturing a polarizing film as described in [16], wherein the laminated film further has an alignment layer, and the alignment layer is deposited on the liquid crystal curing layer. [18] A method for manufacturing a polarizing film as described in [16] or [17], wherein the top-view shape of the region with a low dichroic pigment content is circular, elliptical, oval, or polygonal; when the region is circular, its diameter is 2 cm or less; when the region is elliptical or oval, its major diameter is 2 cm or less; and when the region is polygonal, the diameter of the imaginary circle drawn inscribed in the polygon is 2 cm or less. [19] A method for manufacturing a polarizing film as described in any one of [16] to [18], wherein the liquid crystal curing layer comprises a polymer of a polymeric liquid crystal compound. [20] A method for manufacturing a polarizing film as described in any one of [16] to [19], wherein the length of the polarizing film is 10 m or more. [21] A method for manufacturing a circular polarizer includes: step (1), which involves irradiating a laminated film comprising a liquid crystal curing layer and a substrate layer with a wavelength of 300 nm to 800 nm using a laser; and step (2), which involves laminating the polarizer obtained by step (1) and a phase retardation layer having a 1/4 wavelength film function. [22] In the method for manufacturing a circular polarizer as described in [21], step (1) is performed after step (2). [Effects of the Invention]

The polarizing film of this invention has a narrower area of high visual sensitivity correction transmittance and an excellent appearance. Furthermore, according to the manufacturing method of this invention, the polarizing film of this invention can be obtained with high efficiency.

The polarizing film of the present invention has a liquid crystal curing layer, which contains a liquid crystal compound and has at least a first region and a second region with different values of visual sensitivity correction transmittance. The second region has a higher visual sensitivity correction transmittance than the first region. The shape when viewed from above is circular, elliptical, oval, or polygonal. When the second region is circular, its diameter is 2 cm or less. When the second region is elliptical or oval, its major diameter is 2 cm or less. When the second region is polygonal, the diameter of the imaginary circle drawn in the manner of inscribed in the polygon is 2 cm or less.

The preferred embodiment of the polarizing film and its manufacturing method of the present invention will be described below with reference to the figures. Furthermore, the scope of the present invention is not limited to the embodiment described herein, and various modifications may be made without prejudice to the spirit of the present invention.

<Polarizing Film> Figure 1(a) is a schematic top view of an example of the polarizing film of the present invention, and Figure 1(b) is an X-X cross-sectional view of Figure 1(a).

The polarizing film 1 of this embodiment is a film with anisotropic light absorption function, and has a liquid crystal curing layer 11 containing a liquid crystal compound. The liquid crystal curing layer 11 has at least two regions divided according to the value of the visual sensitivity correction transmittance (Ty), and the at least two regions typically have different contents of dichroic pigments.

The polarizing film 1 may have a liquid crystal curing layer 11, or it may further have a substrate layer 13, an alignment layer 12, and other layers.

In the polarizing film 1 shown in Figure 1(b), an example is shown in which an alignment layer 12 and a liquid crystal curing layer 11 are provided on one side of the substrate layer 13. Alternatively, an alignment layer and a liquid crystal curing layer may be provided on both sides of the substrate layer 13. The structures of the liquid crystal curing layers provided on both sides of the substrate layer 13 may be identical or different from each other.

The polarizing film 1 can be a strip-shaped polarizing film with a length of 10 m or more. In this case, the polarizing film 1 can be made into a wound body wound into a cylinder shape. Steps such as continuously releasing the polarizing film from the wound body, laminating it with the phase difference layer, and cutting it into single sheets can be performed. The length of the strip-shaped polarizing film used to make the wound body is not particularly limited as long as it is 10 m or more, for example, it can be set to 10,000 m or less.

(Liquid Crystal Curing Layer) The liquid crystal curing layer 11 contains a liquid crystal compound and has regions containing the liquid crystal compound and a dichroic pigment. When the polarizing film 1 has polarization characteristics along its plane, it is preferable that the dichroic pigment and the liquid crystal compound are horizontally aligned relative to the plane of the polarizing film 1. When the polarizing film 1 has polarization characteristics along its thickness direction, it is preferable that the dichroic pigment and the liquid crystal compound are horizontally aligned relative to the plane of the polarizing film 1.

The liquid crystal curing layer 11 contains a liquid crystal compound, and typically contains a dichroic pigment.

In the liquid crystal curing layer 11, in the region where the dichroic pigment and liquid crystal compound are horizontally aligned with the polarizing film 1, the ratio of the absorbance A1(λ) in the horizontal direction of the liquid crystal alignment to the absorbance A2(λ) in the vertical direction within the liquid crystal alignment plane for light of wavelength λ nm, i.e., the dichroic ratio (＝A1(λ)/A2(λ)), is preferably 7 or higher, more preferably 20 or higher, and even more preferably 30 or higher. The higher this value, the better the polarization characteristics with excellent absorption selectivity. Although it also depends on the type of dichroic pigment, when the liquid crystal curing layer 11 is a nematic liquid crystal phase, the above ratio is about 5 to 10. When the liquid crystal curing layer 11 is a nematic liquid crystal phase or a lamellar liquid crystal phase as described below, the liquid crystal compound and the dichroic pigment do not separate. This can be confirmed, for example, by surface observation using various microscopes or by scattering measurement using a haze meter.

As shown in Figures 1(a) and 1(b), the liquid crystal curing layer 11 has a first region 11a and a second region 11b that are divided according to the visual sensitivity correction transmittance.

In the polarizing film 1 shown in Figure 1(a), there is an example where there is one of each of the two regions with different visual sensitivity correction transmittance, but the first region and the second region may also have more than two of each.

The polarizing film 1 shown in Figure 1(a) has a first region 11a containing a liquid crystal compound and a dichroic pigment. The second region 11b contains a liquid crystal compound and may or may not contain a dichroic pigment. When the first region 11a contains a dichroic pigment, its content is preferably higher than the content of the dichroic pigment contained in the second region 11b.

The content of dichroic pigments in the liquid crystal curing layer 11 can be determined, for example, by measuring the absorbance at the wavelength of maximum absorption ( _λMAX ) of the dichroic pigments.

The better region 11a is the region with a higher visual sensitivity correction polarization value than the region 2 11b.

Region 11a is preferably a region with high polarization characteristics, for example, the visual sensitivity correction polarization (Py) can be set to 90% or higher, preferably 92% or higher, more preferably 95% or higher, and usually below 100%. The visual sensitivity correction transmittance (Ty) of Region 11a can be set to 35% or higher, preferably 40% or higher, more preferably 42% or higher, and usually below 50%.

Region 2 11b is preferably a low-polarization region with a lower visual sensitivity correction polarization (Py) than Region 1 11a.

The visual sensitivity correction polarization (Py) in Zone 2 11b can be set to less than 10%, preferably less than 5%, even more preferably less than 1%, or it can be 0%.

The second region 11b has a higher visual sensitivity correction transmittance than the first region 11a. The visual sensitivity correction transmittance (Ty) of the second region 11b can be set to, for example, 80% or more, preferably 85% or more, even more preferably 88% or more, and usually below 98%.

The visual sensitivity-corrected transmittance (Ty) and visual sensitivity-corrected polarization (Py) in this manual can be calculated based on the polarization and unit transmittance measured using a spectrophotometer. For example, a device with a clip containing a polarizing element can be used in the spectrophotometer to measure the transmittance along the transmission axis (aligned perpendicularly) and the transmittance along the absorption axis (aligned in the same direction) ( _T2 ) in the wavelength range of visible light, from 380 nm to 780 nm, using a _two -beam method. Regarding the polarization and unit transmittance in the visible light range, the polarization and unit transmittance at each wavelength can be calculated using the following formulas (Formula 1) and (Formula 2), and then the visual sensitivity can be corrected using the 2-degree field of view (C light source) of JIS Z 8701. The corrected polarization (Py) and the corrected transmittance (Ty) are then used to calculate the polarization.

Polarization [%] = {( _T1 - _T2 ) / ( _T1 + _T2 )} × 100 (Equation 1) Transmittance [%] = ( _T1 + _T2 ) / 2 (Equation 2)

The area occupied by region 11a and region 11b shall be appropriately selected according to the characteristics required by polarizing film 1. The ratio of the total area occupied by region 11a and region 11b to the surface area of polarizing film 1 is preferably 90% or more, more preferably 95% or more, and even more preferably 99% or more.

Compared to the combined area occupied by the first region 11a and the second region 11b, the area occupied by the first region 11a is preferably 50% or more, more preferably 70% or more, and even more preferably 80% or more. For example, as shown in Figure 1(a), the area occupied by the second region 11b is smaller than the area occupied by the first region 11a, and the first region 11a is arranged to surround the second region 11b. In the polarizing film 1 shown in Figure 1(a), the first region 11a is arranged to surround a circular second region 11b, but multiple second regions 11b can also be independently provided.

The shape of the first region 11a is not particularly limited. The top view shape of the first region 11a can be circular, elliptical, oval, polygonal, linear, strip-shaped, wavy, etc.

The top view shape of region 2 11b is circular, elliptical, oval, or polygonal. When region 2 11b is circular, its diameter is less than 2 cm, preferably less than 1 cm, and even more preferably less than 0.5 cm. When region 2 11b is circular, its diameter may be more than 0.05 cm or more, or more than 0.1 cm.

When the second region 11b is elliptical or oval, its major axis is less than 2 cm, preferably less than 1 cm, and even more preferably less than 0.5 cm. When the second region 11b is elliptical or oval, its diameter may be more than 0.05 cm or more, or more than 0.1 cm.

When region 11b is a polygon, the diameter of the imaginary circle drawn inscribed in the polygon is 2 cm or less, preferably 1 cm or less, and more preferably 0.5 cm or less. When region 11b is a polygon, the diameter of the imaginary circle may be 0.05 cm or more, or 0.1 cm or more.

The second region 11b of the above-described shape can be preferably used as a region corresponding to the lens position of a camera installed in a smartphone or tablet. In this case, by setting the second region 11b to a region with a visual sensitivity correction unit transmittance (Ty) of 80% or more and a visual sensitivity correction polarization (Py) of 10% or less, the coloring of the second region 11b can be reduced, excellent transparency can be obtained, and thus the performance of the camera can be improved.

Multiple areas 11a and 11b can also be alternately set.

When the polarizing film is a strip-shaped polarizing film, the strip-shaped polarizing film is usually cut to a specific size according to the purpose of the polarizing film. Therefore, it is preferable to set the arrangement of the first region 11a or the second region 11b in the strip-shaped polarizing film in such a way that the first region 11a or the second region 11b is formed at a specific position in the cut polarizing film. For example, when the cut polarizing film is the polarizing film 1 shown in FIG. 1(a), it is preferable to set a plurality of second regions 11b at specific intervals in the length direction and/or width direction of the strip-shaped polarizing film.

The thickness of the first region 11a in the liquid crystal curing layer 11 is preferably 0.5 μm or more, more preferably 1 μm or more, and also preferably 5 μm or less, more preferably 3 μm or less. The thickness of the second region 11b in the liquid crystal curing layer 11 is preferably the same as that of the first region 11a, preferably 0.5 μm or more, more preferably 1 μm or more, and also preferably 5 μm or less, more preferably 3 μm or less. The thickness of the liquid crystal curing layer 11 can be measured by means of an interferometer, a laser microscope, or a stylus thickness gauge.

The thickness of the second region 11b can also be less than the thickness of the first region 11a, but the difference between the thickness of the first region 11a and the thickness of the second region 11b is preferably less than 2 μm, more preferably less than 1 μm, and even more preferably less than 0.5 μm. By setting the thickness of the first region 11a and the second region 11b of the liquid crystal curing layer 11 to the same level, the step difference between the first region 11a and the second region 11b is reduced. In cases where the liquid crystal curing layer 11 has the following phase difference layer or other layers (such as surface protection layer), the entry of bubbles or the generation of wrinkles can be suppressed. Furthermore, when the polarizing film 1 with the liquid crystal curing layer 11 is wound into a cylindrical shape, defects such as winding marks can be suppressed.

(Liquid Crystal Compound) The liquid crystal compound included in the liquid crystal curing layer 11 may be a known liquid crystal compound. There is no particular limitation on the type of liquid crystal compound; rod-shaped liquid crystal compounds, disc-shaped liquid crystal compounds, and mixtures thereof may be used. The liquid crystal compound may be a polymeric liquid crystal compound, a polymeric liquid crystal compound, or a mixture thereof.

Polymerizable liquid crystal compounds can be used as the liquid crystal compound. By using polymerizable liquid crystal compounds, the hue of the polarizing film can be controlled arbitrarily, and the polarizing film can be made much thinner. Furthermore, the polarizing film can be manufactured without stretching treatment, thus producing a non-stretchable polarizing film that does not stretch due to heat.

The term "polymerizable liquid crystal compound" refers to a compound that possesses a polymerizable group and exhibits liquid crystal properties. The polymerizable group refers to a group that participates in a polymerization reaction, preferably a photopolymerizable group. Here, the term "photopolymerizable group" refers to a group that can participate in a polymerization reaction via an active free radical or acid generated from the photopolymerization initiator described below. Examples of polymerizable groups include vinyl, ethoxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, ethylene oxide, and oxocyclobutyl. Among these, acryloxy, methacryloxy, ethoxy, ethylene oxide, or oxocyclobutyl are preferred, and acryloxy is even more preferred. The liquid crystal can be either a thermotropic liquid crystal or a lyotropic liquid crystal. In the case where the liquid crystal curing layer of this embodiment is mixed with dichroic pigments, it is preferable to use a thermotropic liquid crystal.

When the polymerizable liquid crystal compound is a thermotropic liquid crystal, it can be a thermotropic liquid crystal compound that displays a nematic liquid crystal phase or a thermotropic liquid crystal compound that displays a lamellar liquid crystal phase. When the liquid crystal curing layer 11 performs polarization function as a polymer film obtained by polymerization reaction, the liquid crystal state displayed by the polymerizable liquid crystal compound is preferably a lamellar phase, and from the viewpoint of performance enhancement, it is even more preferably a higher-order lamellar phase. More preferably, the liquid crystal compound forms a higher-order stratified liquid crystal compound with a stratified B phase, stratified D phase, stratified E phase, stratified F phase, stratified G phase, stratified H phase, stratified I phase, stratified J phase, stratified K phase, or stratified L phase; and even more preferably, it forms a higher-order stratified liquid crystal compound with a stratified B phase, stratified F phase, or stratified I phase. If the liquid crystal curing layer 11 formed by the polymerizable liquid crystal compound is such a higher-order stratified phase, a region with higher polarization performance can be formed in the liquid crystal curing layer 11. Furthermore, such a region with higher polarization performance is obtained from the Blerg peaks of higher-order structures such as hexagonal phases or crystalline phases obtained in X-ray diffraction measurements. In the polarizing film of the present invention, the first region preferably exhibits a Bourgue peak in X-ray diffraction measurements. This Bourgue peak originates from the periodic structure of molecular alignment, allowing for the acquisition of a film with a periodic interval of 3–6 Å. In the polarizing film 1 of this embodiment, the liquid crystal curing layer 11 comprises a polymer formed by the polymerization of a polymeric liquid crystal compound in a laminar phase state, thereby, for example, bestowing higher polarization characteristics upon the first region 11a, which is therefore preferable. Furthermore, the polymeric liquid crystal compound can be a monomer, or an oligomer or polymer formed by the polymerization of polymeric groups.

For example, it can be confirmed that a polymerizable liquid crystal compound displays a nematic or lamellar liquid crystal phase in the following manner: After coating a polarizing film-forming composition onto a substrate to form a coating film, a heating treatment is performed under conditions where the polymerizable liquid crystal compound does not polymerize, thereby removing the solvent contained in the coating film. Subsequently, the liquid crystal phase exhibited by heating the coating film formed on the substrate to an isotropic phase temperature and then slowly cooling it is examined using texture observation with a polarizing microscope, X-ray diffraction measurement, or differential scanning calorimetry.

As for the polymerizable liquid crystal compound, there is no particular limitation as long as it is a liquid crystal compound having at least one (meth)acrylic acid group. Known polymerizable liquid crystal compounds can be used, preferably compounds that exhibit lamellar liquid crystal properties. Examples of such polymerizable liquid crystal compounds include compounds represented by the following formula (A1) (hereinafter sometimes referred to as "polymerizable liquid crystal compound (A1)").

^{U1 -V1 -W1} -( ^{X1 -Y1} -) _n ^{-X2 -W2 -V2 -U2} (A1) [In formula (A1), ^X1 and ^X2 independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon, wherein the hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon may be replaced by a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group or a nitro group, and the carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon may be replaced by an oxygen atom, a sulfur atom or a nitrogen atom. At least one of ^X1 and ^X2 is a 1,4-epenylphenyl group that may have substituents or a cyclohexane-1,4-diyl group that may have substituents.]

^Y1 is a single-bond or divalent linker.

When n is 1 to 3, and n is 2 or more, the plurality of ^X1s can be the same or different from each other. ^X2 can be the same as or different from any one or all of the plurality of ^X1s . When n is 2 or more, the plurality of ^Y1s can be the same as or different from each other. From the perspective of liquid crystal properties, n is preferably 2 or more.

U ¹ represents a hydrogen atom or (meth)acryloxy group.

U ² represents (meth)acryloxy.

^W1 and ^W2 are independent single-bond or divalent linkage bases.

^V1 and ^V2 independently represent alkyldiyl groups with 1 to 20 carbon atoms that can have substituents. The _-CH2- group constituting the alkyldiyl group can also be substituted with -O-, -CO-, -S, or NH-.

In the polymerizable liquid crystal compound (A1), ^X1 and ^X2 are preferably independently substituted 1,4-epylphenyl or substituted cyclohexane-1,4-diyl, and at least one of ^X1 and ^X2 is substituted 1,4-epylphenyl or substituted cyclohexane-1,4-diyl, preferably trans-cyclohexane-1,4-diyl. Substituents that may be present in the substituted 1,4-epylphenyl or substituted cyclohexane-1,4-diyl may include alkyl groups having 1 to 4 carbon atoms such as methyl, ethyl, and butyl, cyano groups, and halogen atoms such as chlorine and fluorine atoms. Preferably, they are unsubstituted.

Furthermore, regarding the ease with which the polymerizable liquid crystal compound (A1) exhibits stratified liquid crystal properties, it is preferable that the portion represented by formula (A1-1) in formula (A1-1): -( ^X1 - ^Y1- ) _n - ^X2- (A1-1) [where ^X1 , ^Y1 , ^X2 , and n represent the same meanings as described above.] is an asymmetric structure.

As a polymeric liquid crystal compound (A1) whose partial structure (A1-1) is an asymmetric structure, for example, a polymeric liquid crystal compound (A1) in which n is 1 and one ^X1 and ^X2 have different structures can be listed. Two other polymeric liquid crystal compounds (A1) can also be listed: one polymeric liquid crystal compound (A1) is a compound in which n is 2 and two ^Y1 have the same structure, wherein two ^X1 have the same structure and one ^X2 has a different structure from the two ^X1 ; the other polymeric liquid crystal compound (A1) is a compound in which n is 2, and ^one of the two ^X1 is bonded to ^W1 with a different structure from the other ^X1 and ^X2 , while the other ^X1 and ^X2 have the same structure. Examples of polymerizable liquid crystal compounds (A1) include those where n is 3 and the three ^Y1 molecules are identical in structure, wherein any one of the three ^{X1 molecules} and one ^X2 molecule is different from the other three.

^Y1 is preferably _-CH2CH2- , _-CH2O- , _-CH2CH2O- , _-COO- , -OCOO-, _a single bond, -N=N-, ^-CRa = ^CRb- , -C≡C-, ^-CRa =N-, or -CO- ^NRa- . ^Ra and ^Rb independently represent hydrogen atoms or alkyl groups having 1 to 4 carbon atoms. ^Y1 is more preferably _-CH2CH2- , -COO-, or a single bond. When there are multiple ^Y1s , the ^Y1 bonded to ^X2 is more preferably _-CH2CH2- or _-CH2O- . When ^X1 and _X2 are all of the same structure, _it is preferable to have two or more ^Y1s with different bonding ^methods . When there are multiple ^Y1s with different bonding methods, it becomes an asymmetric structure, and therefore tends to exhibit the properties of a stratified liquid crystal.

^U2 is (meth)acryloxy. ^U1 is a hydrogen atom or (meth)acryloxy, preferably (meth)acryloxy. From the viewpoint of improving the interlayer adhesion and heat resistance of the polarizing film, it is preferable that both ^U1 and ^U2 are (meth)acryloxy. (Methacryloxy)acryloxy can be in a polymerized state or an unpolymerized state, preferably in an unpolymerized state.

Examples of alkyldiyl groups represented by ^V1 and ^V2 include methylene, ethyl, propane-1,3-diyl, butane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, decane-1,10-diyl, tetradecane-1,14-diyl, and eicosane-1,20-diyl. ^V1 and ^V2 are preferably alkyldiyl groups with 2 to 12 carbon atoms, and more preferably alkyldiyl groups with 6 to 12 carbon atoms.

Substituents that the alkyl diene may have include cyano groups and halogen atoms, but the alkyl diene is preferably unsubstituted, and more preferably an unsubstituted linear alkyl diene.

^W1 and ^W2 are preferably independent of each other as single key, -O-, -S-, -COO- or -OCOO-, and more preferably as single key or -O-.

As a polymerizable liquid crystal compound, there is no particular limitation as long as it is a polymerizable liquid crystal compound having at least one (meth)acrylic group. Known polymerizable liquid crystal compounds can be used, preferably exhibiting lamellar liquid crystal properties. For a structure that readily exhibits lamellar liquid crystal properties, a molecular structure with asymmetry in its molecular structure is preferred. Specifically, polymerizable liquid crystal compounds having the structures represented by formulas (A-a) to (A-i) and exhibiting lamellar liquid crystal properties are even more preferred. From the viewpoint of readily exhibiting higher-order lamellar liquid crystal properties, structures represented by formulas (A-a), (A-b), or (A-c) are even more preferred. Furthermore, in formulas (A-a) to (A-i), * denotes a bonding bond (single bond).

[Chemistry 1]

Examples of polymerizable liquid crystal compounds include those represented by formulas (A-1) to (A-25). When the polymerizable liquid crystal compound contains a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably in the trans form.

[Chemistry 2]

[Chemistry 3]

[Chemistry 4]

[Chemistry 5]

[Chemistry 6]

Preferably, at least one compound is selected from the group consisting of compounds represented by formulas (A-2), (A-3), (A-4), (A-5), (A-6), (A-7), (A-8), (A-13), (A-14), (A-15), (A-16), and (A-17). As a polymerizable liquid crystal compound, one compound may be used alone, or two or more compounds may be used in combination.

Polymerizable liquid crystal compounds can be used alone or in combination in the liquid crystal curing layer 11. Furthermore, when two or more polymerizable liquid crystal compounds are combined, it is preferable that at least one is a polymerizable liquid crystal compound, and more preferably two or more. By combining two or more polymerizable liquid crystal compounds, liquid crystal properties can be temporarily maintained even at temperatures below the liquid crystal-crystal phase transition temperature. The mixing ratio when combining two polymerizable liquid crystal compounds is typically 1:99 to 50:50, preferably 5:95 to 50:50, and even more preferably 10:90 to 50:50.

Polymerizable liquid crystal compounds can be manufactured, for example, by the known methods described in Lub et al. Recl. Trav. Chim. Pays - Bas, 115, 321 - 328 (1996) or Japanese Patent No. 4719156.

The content of the polymerizable liquid crystal compound in the liquid crystal curing layer 11 is typically 50 to 99.5 parts by mass relative to 100 parts by mass of the solid content of the liquid crystal curing layer 11, preferably 60 to 99 parts by mass, more preferably 70 to 98 parts by mass, and even more preferably 80 to 97 parts by mass. If the content of the polymerizable liquid crystal compound is within the above range, there is a tendency for increased alignment. Here, the solid content refers to the total amount of components obtained by removing the solvent from the liquid crystal curing layer forming composition described below.

(Dichroic Pigments) Dichroic pigments refer to pigments whose absorbance differs along their long axis and short axis. They are pigments that align with liquid crystal compounds to exhibit dichroism. Dichroic pigments themselves can be polymerizable or liquid crystallizable. Preferably, dichroic pigments possess the property of absorbing visible light, and more preferably, they have extremely high absorption wavelengths ( _λMAX ) in the range of 380–680 nm. Examples of such dichroic pigments include acridine pigments, cyanine pigments, anthocyanin pigments, naphthalene pigments, azo pigments, or anthraquinone pigments, with azo pigments being preferred. As azo pigments, examples include monoazo pigments, diazo pigments, triazo pigments, tetraazo pigments, and zirconia pigments, with diazo pigments or triazo pigments being preferred. Dichroic pigments can be used alone or in combination of two or more, but in order to achieve absorption across the entire visible light spectrum, it is preferable to use a combination of three or more dichroic pigments, and even more preferably, a combination of three or more azo pigments.

As an azo dye, for example, the formula (I) ^T1 - ^A1 (-N= ^NA2 ) _p -N= ^NA3 - ^T2 (I) [In formula (I), ^A1 , ^A2 , and ^A3 independently represent 1,4-epenylphenyl, naphth-1,4-diyl, or divalent heterocyclic groups that may have substituents, and ^T1 and ^T2 are independently electron-withdrawing or electron-donating groups, located at positions substantially 180° relative to the azo bond plane. p represents an integer from 0 to 4. When p is 2 or higher, each ^A2 may be the same or different. Within the visible light absorption range, the -N=N- bond may also be substituted with -C=C-, -COO-, -NHCO-, or -N=CH- bonds.] The compound referred to is (hereinafter, sometimes also referred to as "compound (I)").

Substituents that can be arbitrarily present in the 1,4-epenylphenyl, naphth-1,4-diyl, and divalent heterocyclic groups of ^A1 , ^A2 , and ^A3 include: alkyl groups with 1 to 4 carbons such as methyl, ethyl, or butyl; alkoxy groups with 1 to 4 carbons such as methoxy, ethoxy, or butoxy; fluorinated alkyl groups with 1 to 4 carbons such as trifluoromethyl; cyano; nitro; halogen atoms such as chlorine or fluorine; and substituted or unsubstituted amino groups such as amino, diethylamino, and pyrrolidinyl (a substituted amino group refers to an amino group having one or two alkyl groups with 1 to 6 carbons, or an amino group formed by two substituted alkyl groups bonded together to form an alkyldiyl group with 2 to 8 carbons. An unsubstituted amino group is _-NH2 ). Furthermore, alkyl groups with 1 to 6 carbons include methyl, ethyl, or hexyl. Examples of alkyldiyl groups with 2 to 8 carbon atoms include ethylenyl, propane-1,3-diyl, butane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, or octane-1,8-diyl. To encapsulate compound (I) in a high-order liquid crystal structure such as a stratified liquid crystal, ^A1 , ^A2 , and ^A3 are preferably independently unsubstituted 1,4-phenylenyl groups substituted with methyl or methoxy groups, or divalent heterocyclic groups, and p is preferably 0 or 1. Of these, in terms of both ease of molecular synthesis and higher performance, it is more preferable that p is 1 and at least two of the three structures of ^A1 , ^A2 and ^A3 are 1,4-epenylphenyl.

As a divalent heterocyclic group, examples include groups obtained by removing two hydrogen atoms from quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, benzo[a]azole, and benzo[a]azole. When A2 is a divalent heterocyclic group, it is preferable to have a structure in which the molecular bond angle is actually 180°. Specifically, it is even more preferable to have a structure of two 5-membered ring condensations of benzo[ ^a ]thiazole, benzimidazole, and benzo[a]azole.

^T1 and ^T2 are independently electron-withdrawing or electron-donating bases, preferably with different structures, and more preferably ^T1 is an electron-withdrawing base and ^T2 is an electron-donating base, or ^T1 is an electron-donating base and ^T2 is an electron-withdrawing base. Specifically, ^T1 and ^T2 are preferably independently alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, cyano groups, nitro groups, amino groups having one or two alkyl groups having 1 to 6 carbon atoms, or amino groups having two substituted alkyl groups bonded together to form alkyldiyl groups having 2 to 8 carbon atoms, or trifluoromethyl groups. In order to be included in a high-order liquid crystal structure such as a lamellar liquid crystal, it is necessary to be a structure with a smaller molecular exclusion volume. Therefore, it is preferred to be an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, cyano groups, amino groups having one or two alkyl groups having 1 to 6 carbon atoms, or amino groups having two substituted alkyl groups bonded together to form alkyldiyl groups having 2 to 8 carbon atoms.

The following compounds can be listed as azo dyes.

[Chemistry 7]

[Chemistry 8]

In formulas (2-1) to (2-6), ^B1 to ^B20 independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of substituted and unsubstituted amino groups are as described above), a chlorine atom, or a trifluoromethyl group. Furthermore, from the viewpoint of obtaining higher polarization performance, ^B2 , ^B6 , ^B9 , ^B14 , ^B18 , and ^B19 are preferably hydrogen atoms or methyl groups, and more preferably hydrogen atoms.

n1 to n4 represent integers from 0 to 3 independently.

When n1 is 2 or more, the multiple ^B2s can be the same or different. When n2 is 2 or more, the multiple ^B6s can be the same or different. When n3 is 2 or more, the multiple ^B9s can be the same or different. When n4 is 2 or more, the multiple ^B14s can be the same or different.

The anthraquinone pigments mentioned above are preferably compounds represented by formulas (2-7).

[Chemistry 9]

In formula (2-7), ^R1 to ^R8 independently represent hydrogen atoms, ^-Rx , _-NH2 , ^-NHRx , ^-NRx2 , _-SRx or ^halogen atoms.

R ^_x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.

As the pigment mentioned above, the compound represented by formula (2-8) is preferred.

[Chemistry 10]

[In formulas (2-8), ^R9 to ^R15 independently represent a hydrogen atom, ^-Rx , _-NH2 , ^-NHRx , ^-NRx2 , _-SRx ^, or a halogen atom.] ^Rx represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.

The preferred acridine pigments are those represented by formulas (2-9).

[Chemistry 11]

In formula (2-9), ^R16 to ^R23 independently represent hydrogen atoms, ^-Rx , _-NH2 , ^-NHRx , ^-NRx2 , _-SRx or ^halogen atoms.

R ^_x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.

As alkyl groups with 1 to 4 carbons represented by R ^x in formulas (2-7), (2-8), and (2-9), examples include methyl, ethyl, propyl, butyl, pentyl, or hexyl, etc.; as aryl groups with 6 to 12 carbons, examples include phenyl, toluene, xylyl, or naphthyl, etc.

The anthocyanins mentioned above are preferably compounds represented by formula (2-10) and compounds represented by formula (2-11).

[Chemistry 12]

[In equation (2-10), ^D1 and ^D2 independently represent the basis represented by any one of equations (2-10a) to (2-10d). n5 represents an integer from 1 to 3.]

[Chemistry 13]

[Chemistry 14]

[In equation (2-11), ^D3 and ^D4 independently represent the basis represented by any one of equations (2-11a) to (2-11h). n6 represents an integer from 1 to 3.]

[Chemistry 15]

From the viewpoint of obtaining good light absorption characteristics, in regions with polarizing characteristics, such as the first region 11a of the liquid crystal curing layer 11, the content of dichroic pigments (in the case of multiple types, the ratio of their total mass) relative to 100 parts by mass of the polymeric liquid crystal compound is generally preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, and even more preferably 3 to 15 parts by mass. If the content of dichroic pigments is less than this range, light absorption becomes insufficient, and sufficient polarization performance cannot be obtained; if it is more than this range, it will hinder the alignment of liquid crystal molecules. The content of dichroic pigments in the second region 11b of the liquid crystal curing layer 11 is generally lower than that in the first region 11a of the liquid crystal curing layer 11.

(Substrate layer) The polarizing film 1 may also have a substrate layer 13. The substrate layer 13 may, for example, be used to support the alignment layer 12 or the liquid crystal curing layer 21 described below during the manufacture of the polarizing film 1, and may also be used to support the liquid crystal curing layer 11 of the polarizing film 1.

The substrate layer 13 can be a glass substrate or a resin substrate, but is preferably a resin substrate. For the purpose of continuous manufacturing of the polarizing film 1, the substrate layer 13 is more preferably formed by winding a long strip of resin substrate into a cylindrical shape. The resin substrate is preferably a substrate with light transmittance that allows visible light to pass through. Here, light transmittance refers to a transmittance of 80% or more for the optical sensitivity correction element in the wavelength region of 380–780 nm.

The thinner the substrate layer 13, the better; however, if it is too thin, the strength will be reduced and the processability will be poor. The thickness of the substrate layer 13 is usually 5 μm to 300 μm, and preferably 20 μm to 200 μm. Furthermore, the substrate layer 13 can be made peelable, for example, it can be peelable from the polarizing film 1 after the liquid crystal curing layer 11 of the polarizing film 1 is attached to the component forming the display device or the phase retardation layer described below.

Resins that form the base material of resins include: polyolefins such as polyethylene and polypropylene; cyclic olefin resins such as norethene polymers; polyvinyl alcohol; polyethylene terephthalate; polymethacrylate; polyacrylate; cellulose esters such as triacetin, diacetin, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polyurethane; polyether ether; polyether ketone; polyphenylene sulfide and polyphenylene ether, etc.

Examples of commercially available cellulose ester resin base materials include: "Fujitac Film" (manufactured by Fujifilm Inc.); "KC8UX2M", "KC8UY" and "KC4UY" (all manufactured by KONICA MINOLTA Inc.).

Commercially available cyclic olefin resins include: "Topas" (registered trademark) (manufactured by Ticona Corporation); "ARTON" (registered trademark) (manufactured by JSR Corporation); "ZEONOR" (registered trademark), "ZEONEX" (registered trademark) (both manufactured by Zeon Corporation); and "APEL" (registered trademark) (manufactured by Mitsui Chemicals Co., Ltd.). These cyclic olefin resins can be used to form resin substrates by solvent casting, melt extrusion, and other known methods. Commercially available cyclic olefin resin substrates can also be used. As resin base materials for commercially available cyclic olefin resins, examples include: "S-SINA" (registered trademark), "SCA40" (registered trademark) (both manufactured by Sekisui Chemicals Co., Ltd.); "ZEONOR FILM" (registered trademark) (manufactured by Optronics Co., Ltd.); and "ARTON FILM" (registered trademark) (manufactured by JSR Co., Ltd.).

The substrate layer 13 can be a single-layer structure or a multi-layer structure with two or more layers. When the substrate layer 13 is a multi-layer structure, each layer can be formed of the same material or of different materials.

The substrate layer 13 can also function as a quarter-wavelength film. By having the substrate layer 13 function as a quarter-wavelength film, a polarizing film with the function of a circular polarizer can be obtained by combining the substrate layer 13 with the liquid crystal curing layer 11. Therefore, even if the phase retardation layer with the function of a quarter-wavelength film is bonded to the polarizing film 1 without separating it from the substrate layer 13, a circular polarizer can still be obtained. When the substrate layer 13 has a multi-layer structure, a circular polarizer can be obtained by using a component obtained by stacking layers with the function of a half-wavelength film and layers with the function of a quarter-wavelength film, and by stacking the liquid crystal curing layer 11 on the side of the layer with the function of a half-wavelength film. Alternatively, when the substrate layer 13 has a multi-layer structure, a circular polarizer can also be obtained by using a layer with stacked reverse wavelength dispersion that functions as a 1/4 wavelength film and a layer that functions as a positive C-plate.

(Alignment Layer) The polarizing film 1 may also have an alignment layer 12 on the substrate layer 13, the alignment layer 12 being disposed between the substrate layer 13 and the liquid crystal curing layer 11. The alignment layer 12 may have an alignment restraint force that aligns the liquid crystal compound in the liquid crystal curing layer 11 deposited thereon in a desired direction.

The alignment layer 12 facilitates the alignment of the liquid crystal compound. The alignment states of the liquid crystal, such as horizontal alignment, vertical alignment, mixed alignment, and tilted alignment, vary depending on the properties of the alignment layer 12 and the liquid crystal compound, and any combination of these can be selected. For example, if the alignment layer 12 is a material exhibiting horizontal alignment as an alignment constraint force, the liquid crystal compound can form a horizontal alignment or a mixed alignment. If the alignment layer 12 is a material exhibiting vertical alignment, the liquid crystal compound can form a vertical alignment or a tilted alignment. The terms "horizontal," "vertical," etc., refer to the direction of the long axis of the aligned liquid crystal compound when the plane of the polarizing film 1 is used as a reference. For example, vertical alignment refers to the long axis of the polymeric liquid crystal aligned in a direction perpendicular to the plane of the polarizing film 1. Here, "vertical" means 90° ± 20° relative to the plane of the polarizing film 1. The polarizing film 1 preferably has the polarizing characteristics of the plane of the polarizing film 1, and therefore the alignment layer 12 is preferably formed using a material that exhibits horizontal alignment.

When the alignment layer 12 is formed of an alignment polymer, the alignment constraint force can be arbitrarily adjusted according to the surface condition or friction conditions. When it is formed of a photoalignment polymer, it can be arbitrarily adjusted according to polarization irradiation conditions, etc. Furthermore, the liquid crystal alignment can also be controlled by selecting the surface tension or liquid crystal properties of the polymerizable liquid crystal compound.

The thickness of the alignment layer 12 is typically 10 nm to 5000 nm, preferably 10 nm to 1000 nm, and even more preferably 30 nm to 300 nm. Furthermore, the alignment layer 12 formed between the substrate layer 13 and the liquid crystal curing layer 11 is preferably insoluble in the solvent used when the liquid crystal curing layer 11 is formed on the alignment layer 12, and also possesses heat resistance for solvent removal or for heat treatment of liquid crystal alignment.

As the alignment layer 12, examples include alignment films containing alignment polymers, photoalignment films, or groove alignment films. When the substrate layer 13 is rolled out from a cylindrical strip of resin substrate, the alignment layer 12 is preferably a photoalignment film in terms of easy control of its alignment direction.

Examples of directional polymers include polyamides or gelatin containing amide bonds within the molecule, polyimides containing imine bonds within the molecule, and polyamide acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyazole, polyethylimide, polystyrene, polyvinylpyrrolidone, polyacrylic acid, or polyacrylates as their hydrolysates. Polyvinyl alcohol is preferred. These directional polymers can be used alone or in combination of two or more.

Examples of alignment layer forming compounds used in the alignment layer forming step include the following alignment polymer compounds and photoalignment film forming compounds. The alignment layer forming step can be described as follows.

An alignment layer containing an alignment polymer can be obtained, for example, by applying a composition obtained by dissolving the alignment polymer in a solvent (hereinafter sometimes referred to as "alignment polymer composition") to a substrate layer and then removing the solvent, or by applying the alignment polymer composition to a substrate layer, removing the solvent, and then rubbing (friction method).

Examples of solvents used for oriented polymer compositions include: water; alcohols such as methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, methyl solvent, butyl solvent, or propylene glycol monomethyl ether; esters such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, or ethyl lactate; ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl pentyl ketone, or methyl isobutyl ketone; aliphatic hydrocarbons such as pentane, hexane, or heptane; aromatic hydrocarbons such as toluene or xylene; nitrile solvents such as acetonitrile; ethers such as tetrahydrofuran or dimethoxyethane; and chlorinated hydrocarbons such as chloroform or chlorobenzene. These solvents can be used alone or in combination of two or more.

The content of the directional polymer in the directional polymer composition is only required to be within the range where the directional polymer can be completely dissolved in the solvent. The content is preferably 0.1 to 20% by mass relative to the solid content of the solution, and more preferably 0.1 to 10% by mass.

As an alignment polymer composition, commercially available alignment membrane materials can also be used directly. Examples of commercially available alignment membrane materials include Sunever (registered trademark) (manufactured by Nissan Chemical Industries, Ltd.) and Optomer (registered trademark) (manufactured by JSR Corporation).

Methods for coating oriented polymer compositions onto a substrate layer include known methods such as rotational coating, extrusion coating, gravure coating, die coating, rod coating, or lamination, as well as printing methods such as flexographic printing. When manufacturing polarizing film 1 using a continuous roll-to-roll manufacturing method, gravure coating, die coating, or flexographic printing are typically used for the coating method.

A dried coating of the oriented polymer is formed by removing the solvent contained in the oriented polymer composition. Methods for solvent removal include natural drying, ventilation drying, heated drying, and depressurized drying. Subsequently, the dried coating is brought into contact with rotating friction rollers wound with friction cloth to form an oriented layer 12.

Photoalignment films are typically obtained by irradiating an alignment layer with polarized light (preferably polarized UV light) to the alignment layer coating. This alignment layer coating is formed by coating a composition comprising a polymer or monomer having photoreactive groups and a solvent (hereinafter sometimes referred to as a "photoalignment film forming composition") onto a substrate layer. Photoalignment films are particularly advantageous in that the direction of the alignment constraint force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

Photoreactive groups refer to groups that generate liquid crystal alignment energy through light irradiation. Specifically, they are photoreactions that initiate or induce isomerization, dimerization, photocrosslinking, or photodecomposition of the generated molecules, thus becoming the origin of liquid crystal alignment energy. Among these photoreactive groups, those that induce dimerization or photocrosslinking reactions are superior in terms of alignment performance. As a photoreactive group capable of producing the above reaction, it is preferably a group having unsaturated bonds, especially double bonds, and more preferably a group having at least one of the following: carbon-carbon double bonds (C=C), carbon-nitrogen double bonds (C=N), nitrogen-nitrogen double bonds (N=N), and carbon-oxygen double bonds (C=O).

Examples of photoreactive groups with C=C bonds include vinyl, polyene, stilbazole, stilbazolium, chalcone, or cinnamicyl groups. Chalcone or cinnamicyl groups are preferred from the perspective of easy control over reactivity or the expression of orientation restriction forces during photoorientation. Examples of photoreactive groups with C=N bonds include groups with aromatic Schiff bases or aromatic hydrazones. Examples of photoreactive groups with N=N bonds include azophenyl, azonaphthyl, aromatic heterocyclic azo, diazo, or formazanyl groups, or those with azobenzene oxide as the basic structure. As photoreactive groups with C=O bonds, examples include benzophenone, coumarin, anthraquinone, or cis-butenidimino. These groups may also have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, or halogenated alkyl.

As a solvent for the composition for photoalignment film formation, it is preferably a solvent that dissolves polymers and monomers having photoreactive groups. Examples of such solvents that can be used as solvents for the aforementioned alignment polymer compositions include those listed above.

The content of the polymer or monomer with photoreactive groups in the composition for forming the photoalignment film can be appropriately adjusted according to the type of the polymer or monomer with photoreactive groups or the thickness of the photoalignment film to be manufactured, preferably 0.2% by mass or more, and more preferably in the range of 0.3% to 10% by mass. Polyvinyl alcohol or polyimide or other polymeric materials or photosensitizers may also be included, without significantly damaging the properties of the photoalignment film.

As a method for coating the photoalignment film forming composition onto the substrate layer, methods similar to those described above for coating the alignment polymer composition onto the substrate layer 13 can be cited. As a method for removing the solvent from the coated photoalignment film forming composition, methods similar to those for removing the solvent from the alignment polymer composition can be cited.

Polarization irradiation can be performed directly on the dried coating or from the substrate layer side by irradiating the dried coating with polarized light that has passed through the substrate layer. The polarized light used for irradiation is preferably substantially parallel light. The wavelength of the irradiated polarized light can be in the wavelength range where the photoreactive groups of polymers or monomers with photoreactive groups can absorb light energy. Specifically, it is preferably UV (ultraviolet light) in the wavelength range of 250–400 nm. Light sources for polarization irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halogen lamps, KrF, ArF, and other ultraviolet lasers, with high-pressure mercury lamps, ultra-high-pressure mercury lamps, or metal halogen lamps being more preferred. These lamps are superior because they emit greater light intensity than ultraviolet light with a wavelength of 313 nm. Polarized light can be emitted by illuminating the light from the light source through a suitable polarizing element. This polarizing element can be a polarizing mirror, a polarizing prism from Glen-Thompson or Glen-Taylor, or a grating-type polarizing element.

When subjected to friction or polarized light irradiation, if shielding is applied, multiple regions (patterns) with different liquid crystal alignment directions can also be formed.

A groove alignment film is a film with a raised or recessed pattern or a plurality of grooves on its surface. When liquid crystal molecules are placed on a film having a plurality of linear grooves arranged at equal intervals, the liquid crystal molecules align along the direction of the grooves.

Methods for obtaining grooved alignment films include: a method of forming a raised pattern by exposing the surface of a photosensitive polyimide film to an exposure mask with a patterned slit, followed by development and washing; a method of forming a layer of UV-curable resin before curing on a plate-shaped master disc with grooves on its surface, transferring the resin layer to a substrate, and then curing; and a method of pressing a roller-shaped master disc with a plurality of grooves against a UV-curable resin film before curing formed on a substrate to form a raised pattern, followed by curing. Specifically, methods described in Japanese Patent Application Publication No. Hei 6-34976 and Japanese Patent Application Publication No. 2011-242743 are examples.

In order to obtain alignment with less alignment disorder, the width of the protrusion of the groove alignment film is preferably 0.05 μm to 5 μm, the width of the concave portion is preferably 0.1 μm to 5 μm, and the depth of the step difference between the protrusion and concave portion is preferably less than 2 μm, and preferably less than 0.01 μm to 1 μm.

(Other Layers) The polarizing film 1 may also have layers other than the substrate layer 13 and the alignment layer 12. For example, a protective film for the purpose of protecting the surface of the liquid crystal curing layer 11 may be provided on the side of the liquid crystal curing layer 11 opposite to the substrate layer 13. Alternatively, when the substrate layer 13 is peeled off and used separately, a protective film may be provided on the side of the liquid crystal curing layer 11 on which the substrate layer 13 has been peeled off. The protective film may be a single-layer structure or a multi-layer structure. When the protective film is a multi-layer structure, each layer may be formed of the same material or of different materials.

The polarizing film of the present invention can be manufactured by preparing a liquid crystal curing layer and then setting the second region. There are no particular limitations on the method of preparing the liquid crystal curing layer or the method of setting the second region, but it is preferred to manufacture it by the method described below.

<Circular Polarizing Plate> Figures 2(a) to (c) are schematic cross-sectional views showing examples of the circular polarizing plates of the present invention. The polarizing film 1 shown in Figure 1(b) can be fabricated into the circular polarizing plates 5a and 5b shown in Figures 2(a) and (b) by laminating a phase retardation layer 15 having a 1/4 wavelength film function. The phase retardation layer 15 can be deposited on the side of the liquid crystal curing layer 11 of the polarizing film 1 (Figure 2(a)) or on the side of the substrate layer 13 (Figure 2(b)). The circular polarizing plate 5a shown in Figure 2(a) can also be used as the circular polarizing plate 5c (Figure 2(c)) obtained by peeling the substrate layer 13 off from the circular polarizing plate 5a shown in Figure 2(a). In this case, the alignment layer 12 can also be peeled off together with the substrate layer 13.

A circular polarizer can also be obtained by stacking a polarizing film 1 and a multilayered phase retardation layer. In this case, a phase retardation layer obtained by stacking a layer with a 1/2 wavelength film function and a layer with a 1/4 wavelength film function can be used as a multilayered phase retardation layer. By stacking the 1/2 wavelength film function side of the multilayered phase retardation layer and the polarizing film 1, a circular polarizer can be fabricated. Alternatively, a phase retardation layer obtained by stacking a layer with inverse wavelength dispersion function that has a 1/4 wavelength film function and a layer with a positive C-plate function can also be used as a multilayered phase retardation layer to obtain a circular polarizer.

Alternatively, a material that functions as a phase retardation layer can be used as the substrate layer 13 of the polarizing film 1, and then a phase retardation layer can be deposited to form a circular polarizing plate. In this case, the functions of the substrate layer 13 and the phase retardation layer as phase retardation layers can be selected according to the deposition positions of the substrate layer 13 and the phase retardation layer in the circular polarizing plate.

The polarizing film and the phase décor layer can be deposited by using a bonding layer with a known adhesive or bonding agent.

<Manufacturing Method of Polarizing Film>

The method for manufacturing the polarizing film of the present invention is a method for manufacturing a polarizing film in which the content of dichroic pigment in a certain region of the liquid crystal curing layer is lower than that in other regions, and includes a step of irradiating a laminated film having the above-mentioned liquid crystal curing layer and substrate layer with a laser of wavelength of 300 nm to 800 nm.

A laminated film having a liquid crystal curing layer and a substrate is not particularly limited as long as it has a liquid crystal curing layer on at least one side of the substrate layer. The following protective films can be used as substrates. In the above-mentioned laminated films, the protective film may be deposited not only as a substrate layer but also on the side of the liquid crystal curing layer opposite to the substrate.

When the laminated film further comprises an alignment layer, it is preferable to sequentially laminate an alignment layer and a liquid crystal curing layer on a substrate layer. The laminated film further comprising an alignment layer can be manufactured by the following steps: applying an alignment layer forming composition to one side of the substrate layer to form an alignment layer; and then applying a liquid crystal curing layer forming composition to the side on which the alignment layer is formed to form a liquid crystal curing layer.

In the alignment layer formation step, the substrate layer 13 may also undergo surface treatment before applying the alignment layer forming composition. Methods for surface treatment include, for example, corona treatment, plasma treatment, laser treatment, ozone treatment, saponification treatment, flame treatment, coupling agent coating treatment, and primer treatment. The alignment layer forming composition may include compositions containing resin materials used to form the aforementioned alignment polymer composition, photoalignment film forming composition, and groove alignment film. The methods for forming the alignment layer using each composition are also as described above. For example, when the alignment layer forming composition contains a photoalignable polymer, the alignment layer forming step can be performed by irradiating the alignment layer coating formed by the alignment layer forming composition with polarized light to form an alignment layer with alignment constraint force in a specific direction.

The liquid crystal curing layer forming composition comprises a liquid crystal compound and a dichroic pigment, preferably comprising a solvent and a polymerization initiator, and may also include a sensitizer, a polymerization inhibitor, a leveling agent, and a reactive additive. The liquid crystal compound and dichroic pigment described above can be used. The solvent, polymerization initiator, sensitizer, polymerization inhibitor, leveling agent, and reactive additive can be used.

Methods for applying compositions for forming liquid crystal curing layers include extrusion coating, direct gravure coating, reverse gravure coating, CAP (capillary) coating, slotted coating, microgravure coating, die coating, and inkjet coating. Methods using coating machines such as dip coating machines, rod coating machines, and rotary coating machines can also be listed. In the case of continuous coating in a roller-to-roll manner, coating methods such as microgravure, inkjet, slit coating, and die coating are preferred. When coating on a single substrate such as glass, rotational coating, which has higher uniformity, is preferred. In the case of coating in a roller-to-roll manner, an alignment film forming composition can also be coated on the substrate layer to form an alignment layer, and then the liquid crystal curing layer forming composition can be continuously coated on the obtained alignment layer.

When forming a liquid crystal curing layer using an assembly for forming a liquid crystal curing layer, the solvent is removed from the liquid crystal curing layer forming assembly to form a coating layer for forming the liquid crystal curing layer. As a method for removing the solvent, the same method as that used for removing solvent using self-aligning polymer compositions can be used, such as natural drying, ventilation drying, heated drying, depressurized drying, and combinations thereof. Natural drying or heated drying is preferred. The drying temperature is preferably in the range of 0–200°C, more preferably in the range of 20–150°C, and even more preferably in the range of 50–130°C. The drying time is preferably 10 seconds to 10 minutes, more preferably 30 seconds to 5 minutes.

When the liquid crystal compound contained in the liquid crystal curing layer forming assembly is a polymeric liquid crystal compound, it is preferable to irradiate the liquid crystal curing layer coating formed by the liquid crystal curing layer forming step with an active energy line to cause photopolymerization of the polymeric liquid crystal compound, thereby forming a liquid crystal curing layer that is a polymer layer of the polymeric liquid crystal compound. The active energy to be irradiated is appropriately selected based on the type of polymeric liquid crystal compound contained in the liquid crystal curing layer coating (especially the type of photopolymerizable functional groups possessed by the polymeric liquid crystal compound), the type of photopolymerization initiator (if a photopolymerization initiator is included), and the amount thereof. Specifically, one or more types of light can be selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, alpha rays, beta rays, and gamma rays. In terms of ease of control over the polymerization reaction and the availability of devices widely used in the field for photopolymerization, ultraviolet light is preferred, and more preferably, the type of polymerizable liquid crystal compound can be selected in a manner that allows photopolymerization by ultraviolet light.

As light sources for active energy lines, examples include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten filament lamps, gallium lamps, excimer lasers, LED (light emitting diode) light sources emitting light in the wavelength range of 380–440 nm, chemical lamps, black lamps, microwave-excited mercury lamps, and metal halogen lamps.

The irradiation intensity of the active energy line is typically 10 mW/ ^cm² to 3000 mW/ ^cm² . Preferably, the irradiation intensity is within the wavelength range effective for activating cationic polymerization initiators or free radical polymerization initiators. The irradiation time of the active energy line is typically 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and even more preferably 0.1 seconds to 1 minute. If irradiation is performed once or multiple times at this active energy line intensity, the cumulative light intensity can be set to 10 mJ/ ^cm² to 3000 mJ/ ^cm² , preferably 50 mJ/ ^cm² to 2000 mJ/ ^cm² , and more preferably 100 mJ/ ^cm² to 1000 mJ/ ^cm² . When the cumulative light intensity is below this range, the curing of the polymeric liquid crystal compound becomes insufficient, resulting in poor transferability. Conversely, when the cumulative light intensity is above this range, the liquid crystal curing layer exhibits coloration.

(Soluble) The liquid crystal curing layer forming assembly may also contain a solvent. Generally, polymerizable liquid crystal compounds have higher viscosity; therefore, when using polymerizable liquid crystal compounds as liquid crystal compounds, they are easily coated by using a liquid crystal curing layer forming assembly containing a solvent, resulting in easy formation of a liquid crystal curing layer. Preferably, the solvent is capable of completely dissolving both the polymerizable liquid crystal compound and the dichroic pigment. Preferably, it is a solvent that is inert to the polymerization reaction of the polymerizable liquid crystal compound.

As solvents, the following can be listed: methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, or propylene glycol monomethyl ether, etc.; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, or propylene glycol methyl ether acetate or ethyl lactate, etc.; acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, or methyl isobutyl ketone, etc. Ketone solvents such as ketones; aliphatic hydrocarbon solvents such as pentane, hexane, or heptane; aromatic hydrocarbon solvents such as toluene or xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran or dimethoxyethane; chlorine-containing solvents such as chloroform or chlorobenzene; amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidineone. These solvents can be used alone or in combination of two or more.

The solvent content in the liquid crystal curing layer forming assembly is preferably 50-98% by mass relative to the total amount of the liquid crystal curing layer forming assembly. In other words, the solid content in the liquid crystal curing layer forming assembly is preferably 2-50% by mass. If the solid content is less than 50% by mass, the viscosity of the liquid crystal curing layer forming assembly becomes lower, thus the thickness of the liquid crystal curing layer 21 becomes approximately uniform and less prone to unevenness. The solid content can be determined by considering the desired thickness of the liquid crystal curing layer 21.

(Polymerization Initiator) The liquid crystal curing layer forming composition may also contain a polymerization initiator. A polymerization initiator is a compound that can be used when a polymerizable liquid crystal compound is used as the liquid crystal compound to initiate the polymerization reaction of the polymerizable liquid crystal compound, etc. From the viewpoint that the polymerization initiator is independent of the phase state of the thermotropic liquid crystal, a photopolymerization initiator that generates active free radicals through the action of light is preferred.

Examples of polymerization initiators include benzoin compounds, benzophenone compounds, benzyl ketone compounds, acetylsinox compounds, triterpenoid compounds, monazine salts, or strontium salts.

As compounds of benzoin, examples include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

Examples of benzophenone compounds include benzophenone, methyl benzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and 2,4,6-trimethylbenzophenone.

Examples of phenyl ketone compounds include diethoxyacetophenone, 2-methyl-2-morpholino-1-(4-methylthienyl)propane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propane-1-one, 1-hydroxycyclohexylphenyl one, or oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane-1-one.

Examples of phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

Examples of trichloromethyl compounds include 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-trichloromethyl, 2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-trichloromethyl, 2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-trichloromethyl, and 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)ethyl [Alkenyl]-1,3,5-trisyl, 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)vinyl]-1,3,5-trisyl, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)vinyl]-1,3,5-trisyl or 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)vinyl]-1,3,5-trisyl, etc.

Commercially available products can also be used as polymerization initiators. Commercially available polymerization initiators include: Irgacure (registered trademark) 907, 184, 651, 819, 250, 369, 379, 127, 754, OXE01, OXE02, or OXE03 (manufactured by Ciba Specialty Chemicals Co., Ltd.); Seikuol (registered trademark) BZ, Z, or BEE (manufactured by Seiko Chemical Co., Ltd.); Kayacure (registered trademark) BP100 or UVI-6992 (manufactured by Dow Chemical Co., Ltd.); Adeka Optomer SP-152, N-1717, N-1919, SP-170, Adeka Arkls NCI-831, Adeka Arkls NCI-930 (manufactured by ADEKA Corporation); TAZ-A or TAZ-PP (Nihon). (manufactured by SiberHegner Co., Ltd.); TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.), etc. The polymerization initiator in the liquid crystal curing layer forming composition can be one type, or two or more types of polymerization initiators can be mixed in accordance with the light source.

The content of the polymerization initiator in the liquid crystal curing layer composition can be appropriately adjusted according to the type or amount of the polymerizable liquid crystal compound. The content of the polymerizable liquid crystal compound is typically 0.1 to 30 parts by mass per 100 parts by mass, preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass. If the content of the polymerization initiator is within the above range, polymerization can proceed without disrupting the orientation of the polymerizable liquid crystal compound.

(Sensitizer) The liquid crystal curing layer forming composition may also contain a sensitizer. The sensitizer is preferably used when a polymerizable liquid crystal compound is used as the liquid crystal compound. When a polymerizable liquid crystal compound having a photopolymerizable group is used, the sensitizer is preferably a photosensitizer. Examples of sensitizers include: ketone and 9-oxothiophene. ketone compounds (e.g., 2,4-diethyl-9-oxosulfuron) 2-Isopropyl-9-oxosulfuron (etc.); anthracene and anthracene compounds containing alkoxyanthracene (such as dibutoxyanthracene); phenanthrene or cinnamene, etc.

When the liquid crystal curing layer forming composition contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal compound contained in the liquid crystal curing layer forming composition can be further promoted. The amount of the sensitizer used relative to 100 parts by mass of the polymerizable liquid crystal compound is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 0.5 to 3 parts by mass.

(Polymerization Inhibitor) From the viewpoint of ensuring the stable progress of the polymerization reaction, the liquid crystal curing layer forming composition may also contain a polymerization inhibitor. Polymerization inhibitors are preferable when using a polymerizable liquid crystal compound as the liquid crystal compound, as they control the extent of the polymerization reaction of the polymerizable liquid crystal compound.

Examples of polymerization inhibitors include: hydroquinone, alkoxy-containing hydroquinone, alkoxy-containing catechol (such as butylcatechol), gallnutol, free radical scavengers such as 2,2,6,6-tetramethyl-1-piperidinoxy radical; thiophenol compounds; β-naphthylamine compounds or β-naphthol compounds, etc.

When the composition for forming the liquid crystal curing layer contains a polymerization inhibitor, the content of the polymerization inhibitor relative to 100 parts by mass of the polymerizable liquid crystal compound is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 0.5 to 3 parts by mass. If the content of the polymerization inhibitor is within the above range, polymerization can proceed without causing misalignment of the polymerizable liquid crystal compound.

(Leveling Agent) The liquid crystal curing layer forming composition may also contain a leveling agent. A leveling agent is an additive that adjusts the flowability of the composition to make the film obtained by coating the composition flatter. Examples of leveling agents include organic modified polysiloxane oil-based, polyacrylate-based, or perfluoroalkyl-based leveling agents. Specific examples include: DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all manufactured by Toray Industries, Ltd.); KP321, KP323, KP324, KP326, KP340, KP341, X22-161A, KF6001 (all manufactured by Shin-Etsu Chemical Industries, Ltd.); TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF-4446, TSF4452, TSF4460 (all manufactured by Mitu Advanced Materials Japan Ltd.); fluorinert (registered trademark) FC-72, fluorinert FC-40, Fluorinert FC-43, Fluorinert FC-3283 (all manufactured by Sumitomo 3M); MEGAFAC (registered trademark) R-08, MEGAFAC R-30, MEGAFAC R-90, MEGAFAC F-410, MEGAFAC F-411, MEGAFAC F-443, MEGAFAC F-445, MEGAFAC F-470, MEGAFAC F-477, MEGAFAC F-479, MEGAFAC F-482, MEGAFAC F-483 (all manufactured by DIC); Eftop (trade name) EF301, Eftop EF303, Eftop EF351, Eftop EF352 (all manufactured by Mitsubishi Materials Electronics Chemicals, Inc.); Surflon (registered trademark) S-381, Surflon S-382, Surflon S-383, Surflon S-393, Surflon SC-101, Surflon SC-105, KH-40, SA-100 (all manufactured by AGC Ching-mei Chemicals, Inc.); trade names E1830 and E5844 (manufactured by Daikin Precision Chemical Research Institute, Inc.); BM-1000, BM-1100, BYK-352, BYK-353, or BYK-361N (all trade names; manufactured by BM Chemie, Inc.), etc. Among these, polyacrylate-based leveling agents or perfluoroalkyl-based leveling agents are preferred.

When the liquid crystal curing layer forming composition contains a leveling agent, the amount of leveling agent relative to 100 parts by mass of the liquid crystal compound is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.1 to 3 parts by mass. If the amount of leveling agent is within the above range, it tends to facilitate the horizontal alignment of the liquid crystal compound and result in a smoother liquid crystal curing layer. If the amount of leveling agent relative to the liquid crystal compound exceeds the above range, it tends to cause unevenness in the resulting liquid crystal curing layer. The liquid crystal curing layer forming composition may also contain two or more leveling agents.

(Reactive Additives) The liquid crystal curing layer forming composition may also contain reactive additives. Preferably, the reactive additive has carbon-carbon unsaturated bonds and active hydrogen reactive groups within its molecule. Furthermore, the term "active hydrogen reactive group" here refers to a group reactive to groups with active hydrogen, such as carboxyl (-COOH), hydroxyl (-OH), and amino ( _-NH₂ ), with examples including glycidyl, acezolinyl, carbodiimide, aziridinyl, amide, isocyanate, thioisocyanate, and maleic anhydride. The number of carbon-carbon unsaturated bonds or active hydrogen reactive groups in reactive additives is usually 1 to 20, preferably 1 to 10.

In reactive additives, it is preferable to have at least two active hydrogen reactive groups. In this case, the multiple active hydrogen reactive groups may be the same or different.

The carbon-carbon unsaturated bonds in the reactive additive can be carbon-carbon double bonds, carbon-carbon triple bonds, or combinations thereof, preferably carbon-carbon double bonds. Preferably, the reactive additive contains carbon-carbon unsaturated bonds as vinyl and/or (meth)acrylic groups. Further, it is more preferably a reactive additive whose active hydrogen reactive group is at least one selected from the group consisting of epoxy groups, glycidyl groups, and isocyanate groups, and even more preferably a reactive additive having both acrylamide and isocyanate groups.

Specific examples of reactive additives include: compounds containing (meth)acrylic acid and epoxy groups, such as methacrylic acid oxyglycidyl ether or acryloxyglycidyl ether; compounds containing (meth)acrylic acid and oxacyclobutane acrylate or oxacyclobutane methacrylate; compounds containing (meth)acrylic acid and lactone groups, such as lactone acrylate or lactone methacrylate; compounds containing vinyl and acezoline groups, such as vinyl acezoline or isopropenyl acezoline; and oligomers of compounds containing (meth)acrylic acid and isocyanate groups, such as methyl isocyanate acrylate, methyl isocyanate methacrylate, ethyl 2-isocyanate acrylate or ethyl 2-isocyanate methacrylate. Furthermore, compounds containing vinyl or extended vinyl groups and anhydrides, such as methacrylic anhydride, acrylic anhydride, maleic anhydride, or vinyl maleic anhydride, can be listed. Among these, methacryloyloxyglycidyl ether, acryloxyglycidyl ether, methyl isocyanate acrylate, methyl isocyanate methacrylate, vinyl methazolin, ethyl 2-isocyanate acrylate, ethyl 2-isocyanate methacrylate, or oligomers thereof are preferred, especially methyl isocyanate acrylate, ethyl 2-isocyanate acrylate, or oligomers thereof.

Specifically, the compound represented by the following formula (Y) is preferred.

[Chemistry 16]

In formula (Y), n represents an integer from 1 to 10, and ^{R1 '} represents a divalent aliphatic or alicyclic hydrocarbon with 2 to 20 carbon atoms, or a divalent aromatic hydrocarbon with 5 to 20 carbon atoms. One of the two ^{R2 's} in each repeating unit is -NH-, and the other is the group represented by >NC(=O) ^{-R3 '} . ^{R3 '} represents a hydroxyl group or a group with carbon-carbon unsaturated bonds.

In formula (Y) ^{, at least one of the R3's is a group} having carbon-carbon unsaturated bonds.

Of the reactive additives represented by the above formula (Y), the compound represented by formula (YY) is preferred (hereinafter, sometimes referred to as compound (YY)) (and n has the same meaning as above).

[Chemistry 17]

For compounds (YY), commercially available products can be used directly or refined as needed. Commercially available products include, for example, Laromer (registered trademark) LR-9000 (manufactured by BASF).

When the composition for forming the liquid crystal curing layer contains a reactive additive, the content of the reactive additive is usually 0.01 to 10 parts by mass relative to 100 parts by mass of the liquid crystal compound, and preferably 0.1 to 5 parts by mass.

The laminated film in this invention can also have a protective film laminated on the liquid crystal curing layer obtained by the above method.

(Protective Film) The aforementioned protective film may be a film comprising a thermoplastic resin having light transmittance (preferably optical transparency). Such thermoplastic resins include, for example: cyclic polyolefin resins (such as polypropylene resins) and cyclic polyolefin resins (such as norethene resins); cellulose resins such as triacetyl cellulose and diacetyl cellulose; and polyester resins such as polyethylene terephthalate and polybutylene terephthalate. Resins; polycarbonate resins; such as methyl methacrylate resins, (meth)acrylic resins; polystyrene resins; polyvinyl chloride resins; acrylonitrile-butadiene-styrene resins; acrylonitrile-styrene resins; polyvinyl acetate resins; polyvinylidene chloride resins; polyamide resins; polyacetal resins; modified polyphenylene ether resins; polyurethane resins; polyether urethane resins; polyarylate resins; polyamide-imide resins; polyimide resins, etc.

As chain polyolefin resins, examples include chain olefin homopolymers such as polyethylene resin (a homopolymer of ethylene, or a copolymer based on ethylene) and polypropylene resin (a homopolymer of propylene, or a copolymer based on propylene). In addition, copolymers containing two or more chain olefins can also be listed.

Cyclic polyolefin resins are a general term for resins polymerized using cyclic alkenes as polymerizing units. Examples include the resins described in Japanese Patent Application Publication Nos. 1-240517, 3-14882, and 3-122137. Specific examples of cyclic polyolefin resins include ring-opening polymers (copolymers) of cyclic alkenes, addition polymers of cyclic alkenes, copolymers of cyclic alkenes with chain alkenes such as ethylene and propylene (typically random copolymers), graft polymers obtained by modifying these resins with unsaturated carboxylic acids or their derivatives, and their hydrogenates. Preferably, a norethene-based resin is used, wherein the norethene-based resin uses a norethene monomer, such as norethene or a polycyclic norethene monomer, as the cyclic olefin.

Polyester resins are resins containing ester bonds, excluding the cellulose ester resins described below. They are generally polycondensates containing polycarboxylic acids or their derivatives and polyols. As polycarboxylic acids or their derivatives, dicarboxylic acids or their derivatives can be used, such as terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalate. As polyols, diols can be used, such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexanediol. A representative example of polyester resins is polyethylene terephthalate, a polycondensate of terephthalic acid and ethylene glycol.

(Meth)acrylate resins are resins whose main constituent monomers are compounds having (meth)acrylic groups. Specific examples of (meth)acrylate resins include: poly(meth)acrylates such as polymethyl methacrylate; methyl methacrylate-(meth)acrylate copolymers; methyl methacrylate-(meth)acrylate copolymers; methyl methacrylate-acrylate-(meth)acrylate copolymers; methyl methacrylate-styrene copolymers (MS resin, etc.); copolymers of methyl methacrylate with compounds having alicyclic hydrocarbon groups (e.g., methyl methacrylate-cyclohexyl methacrylate copolymers, methyl methacrylate-norphoacrylate copolymers, etc.). It is preferable to use a polymer with poly(meth)acrylate _C1-6 alkyl ester as the main component, such as poly(meth)acrylate, and even more preferably to use a methyl methacrylate resin with methyl methacrylate as the main component (50-100% by weight, preferably 70-100% by weight).

Cellulose ester resins are esters of cellulose and fatty acids. Specific examples of cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Also, copolymers of these, or those obtained by modifying a portion of the hydroxyl group with other substituents, can also be listed. Cellulose triacetate (triacetin) is particularly preferred.

Polycarbonate resins are engineering plastics that consist of polymers with monomer units bonded by carbonate groups.

The thickness of the protective film is typically 1–100 μm, but from the perspective of strength or operability, 5–60 μm is preferred, and more preferably 5–50 μm. If the thickness is within this range, the liquid crystal curing layer is mechanically protected, and even when exposed to humid and hot environments, the liquid crystal curing layer will not shrink, thus maintaining stable optical properties.

The protective film can be adhered to the liquid crystal curing layer, for example, via an adhesive layer. As the adhesive for forming the adhesive layer, a water-based adhesive, an active energy line curing adhesive, or a thermosetting adhesive can be used, preferably a water-based adhesive or an active energy line curing adhesive.

Examples of aqueous adhesives include adhesives containing aqueous solutions of polyvinyl alcohol (PVA) resins and aqueous two-component carbamate emulsion adhesives. Among these, aqueous adhesives containing aqueous solutions of PVA resins are preferred. As for PVA resins, in addition to vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate (a homopolymer of vinyl acetate), polyvinyl alcohol copolymers obtained by saponifying copolymers of vinyl acetate and other monomers that can copolymerize with it, or modified PVA polymers obtained by partially modifying the hydroxyl groups of such copolymers, can also be used. Aqueous adhesives may include aldehyde compounds (such as glyoxal), epoxy compounds, melamine compounds, hydroxymethyl compounds, isocyanate compounds, amine compounds, and crosslinking agents such as polyvalent metal salts.

When using water-based adhesives, it is preferable to apply a drying step to remove the water contained in the water-based adhesive after bonding the liquid crystal curing layer to the protective film. Alternatively, a curing step can be performed after the drying step, for example, at a temperature of 20–45°C.

The aforementioned active energy line curing adhesive is an adhesive containing a curing compound that is cured by irradiation with active energy lines such as ultraviolet light, visible light, electron beams, and X-rays, preferably an ultraviolet curing adhesive.

The aforementioned curing compounds can be cationicly polymerizable or free-radically polymerizable. Examples of cationicly polymerizable curing compounds include epoxide compounds (compounds having one or more epoxy groups within the molecule), oxocyclobutane compounds (compounds having one or more oxocyclobutane rings within the molecule), or combinations thereof. Examples of free-radically polymerizable curing compounds include (meth)acrylic acid compounds (compounds having one or more (meth)acrylic acid groups within the molecule), other vinyl compounds with double bonds exhibiting free-radical polymerizability, or combinations thereof. Cationicly polymerizable and free-radically polymerizable curing compounds can also be used together. Active energy line hardening adhesives typically further include cationic polymerization initiators and/or free radical polymerization initiators for initiating the hardening reaction of the aforementioned hardening compounds.

When bonding the liquid crystal curing layer to the protective film, surface activation treatment can be applied to at least one of the bonding surfaces to improve adhesion. Examples of surface activation treatments include: dry treatments such as corona treatment, plasma treatment, discharge treatment (global discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, and ionizing active radiation treatment (ultraviolet treatment, electron beam treatment, etc.); and wet treatments such as ultrasonic treatment using solvents like water or acetone, saponification treatment, and tackifying coating treatment. These surface activation treatments can be performed individually or in combination of two or more.

When a protective film is applied to both sides of a liquid crystal curing layer, the adhesive used to apply the protective film can be the same type of adhesive or different types of adhesive.

(Laser irradiation step) In this invention, the step of irradiating the laminated film with a laser of wavelength from 300 nm to 800 nm can be performed, for example, in the following embodiments.

There are no particular limitations on the lasers mentioned above; solid lasers such as YAG (yttrium aluminum garnet), YLF (yttrium lithium fluoride), YVO4, and titanium sapphire lasers can be used.

In the above steps, the wavelength of the laser can be appropriately selected according to the composition or thickness of the liquid crystal curing layer or substrate being irradiated, preferably 350 nm or higher, more preferably 400 nm or higher. The upper limit of the laser wavelength is preferably 750 nm, more preferably 700 nm.

When irradiating the laminated film with a laser, it is preferable to irradiate the liquid crystal curing layer with a laser. Furthermore, when irradiating the protective film with a laser, the transmittance of the laser wavelength on the side of the protective film to which the laser is irradiated is preferably 20% or more, and more preferably 50% or more.

In the above steps, the irradiation conditions of the laser light can be appropriately selected according to the composition or thickness of the liquid crystal curing layer or substrate being irradiated, the laser device, etc. For example, when using a solid-state laser, the laser power is preferably 0.3 W or more, more preferably 0.5 W or more, preferably 10 W or less, and more preferably 5 W or less. The switching frequency is preferably 1000 Hz or more, more preferably 15000 Hz or more, and more preferably 1,000,000 Hz or less, and more preferably 300,000 Hz or less. The scanning speed is preferably 100 mm/s or more, more preferably 200 mm/s or more, and more preferably 10,000 mm/s or less, and more preferably 5,000 mm/s or less. By irradiating under these conditions, heat damage to the substrate can be suppressed and areas with lower dichroic pigments can be formed efficiently.

The polarizing film is preferably manufactured continuously using a roller-to-roll method. For example, it can be manufactured by continuously performing the steps of pre-winding a laminate having a substrate and a liquid crystal curing layer into a cylindrical shape, conveying the laminate while one side is being wound out, and then laminating a protective film, and then performing a laser irradiation step. In the protective film lamination step, the laminate is obtained by conveying the protective film while one side is being wound out of the cylindrical shape and then laminating and attaching it to the laminate. In the laser irradiation step, the laminate can be continuously conveyed while the laser is being irradiated. After the laser irradiation step, the obtained polarizing film can be further wound into a cylindrical shape to form a wound body. In the case of continuous manufacturing of polarizing film, for example, polarizing film with a length of more than 10 m can be produced.

In the manufacturing method of the polarizing film of the present invention, an alignment layer formation step or a liquid crystal curing layer formation step can be included to continuously manufacture the polarizing film. Furthermore, when the alignment layer formation step is included, the substrate layer, wound into a cylindrical shape, is conveyed while being rolled out, and the alignment layer forming assembly is continuously applied to the substrate layer using a coating apparatus to form the alignment layer. When the liquid crystal curing layer formation step is performed continuously, the liquid crystal curing layer forming assembly is applied to the side of the substrate layer with the alignment layer while the substrate layer with the alignment layer is continuously conveyed to form the liquid crystal curing layer.

<Manufacturing Method of Circular Polarizing Plate> The circular polarizing plate of the present invention can be manufactured by laminating the polarizing film and the retardation layer of the present invention. As described above, when the polarizing film is a strip polarizing film with a length of 10 m or more that is continuously manufactured, it is preferable to use a strip retardation layer with a length of 10 m or more as the retardation layer, and to laminate the strip polarizing film and the strip retardation layer while continuously conveying both, thereby forming a strip laminate. In this case, it is preferable to apply an adhesive or bonding agent to at least one of the strip polarizing film and the strip retardation layer and then laminate both.

The method for manufacturing the circular polarizer of the present invention may also include a step of cutting a strip-shaped laminate obtained by laminating a strip-shaped polarizer and a strip-shaped retardation layer into single pieces of a specific size in order to mount the polarizer on a display device of a specific size. In the cutting step, it is preferable to cut the strip-shaped laminate in at least one direction, either the length direction or the width direction. In this case, it is preferable to determine the cutting position in the strip-shaped laminate by arranging the second region of the liquid crystal curing layer in the cut single piece at a specific location. [Example]

The invention will be further described in detail based on the embodiments. However, the invention is not limited to these embodiments.

(Visual Sensitivity Corrected Transmittance (Ty), Visual Sensitivity Corrected Polarization (Py)) For each sample, the visual sensitivity corrected polarization (Ty) and visual sensitivity corrected polarization (Py) are calculated in the following order.

Sequence: Using a spectrophotometer (Shimadzu UV-3150 manufactured by Shimadzu Corporation) equipped with a clamp containing a polarizing element, the transmittance along the transmission axis ( _T1 ) and the transmittance along the absorption axis ( _T2 ) were measured in the wavelength range of 380 nm to 780 nm using a two-beam method. The clamp is equipped with a mesh that filters out 50% of the light. Using Equations (1) and (2) below, the transmittance and polarization at each wavelength were calculated. Then, using the 2-degree field of view (C light source) of JIS Z 8701, visual sensitivity correction was performed to calculate the visual sensitivity-corrected transmittance (Ty) and visual sensitivity-corrected polarization (Py).

Transmittance [%] = ( _T1 + _T2 )/2 (Equation 1) Polarization [%] = {( _T1 - _T2 )/( _T1 + _T2 )} × 100 (Equation 2)

[Example 1] (Preparation of an alignment layer forming compound) Two parts of polymer (1) with a number average molecular weight of 28,000 as represented by the following chemical formula were mixed with 98 parts of o-xylene and the mixture was stirred at 80°C for 1 hour to obtain an alignment layer forming compound.

Polymer (1)

(In the formula, Me represents methyl)

(Preparation of an assembly for forming a liquid crystal curing layer) An assembly for forming a liquid crystal curing layer is obtained by mixing the following components and stirring at 80°C for 1 hour. The dichroic pigment used is an azo pigment described in an embodiment of Japanese Patent Application Publication No. 2013-101328. ・75 parts of the polymerizable liquid crystal compound represented by formulas (1-6)

• 25 parts of the polymeric liquid crystal compound represented by formula (1-7)

• 2.8 parts of the dichroic pigment (1) shown below

• 2.8 parts of the dichroic pigment (2) shown below

• 2.8 parts of the dichroic pigment (3) shown below

• Polymerization initiator: 2-Dimethylamino-2-benzyl-1-(4-morpholinylphenyl)butane-1-one (Irgacure 369; manufactured by Ciba Specialty Chemicals) 6 parts • Leveling agent: Polyacrylate compound (BYK-361N; manufactured by BYK-Chemie) 1.2 parts • Solvent: Cyclopentanone 250 parts

(Manufacturing of Lamination 1) A 50×50 mm piece of triacetyl cellulose membrane (KC4UY-TAC, Konica Minolta, Inc.; 40 μm thickness) serving as the substrate layer was cut and its surface was subjected to corona treatment (AGF-B10; Kasuga Electric Co., Ltd.). The visual sensitivity corrected transmittance (Ty) of the above substrate layer at 355 nm was 2%, and the visual sensitivity corrected transmittance (Ty) at 532 nm was 92%.

After applying the above-mentioned alignment layer forming composition to the corona-treated film surface using a rod coating machine, the film is dried in a drying oven set to 120°C for 1 minute to obtain the alignment layer coating. The alignment layer is then formed by irradiating the alignment layer coating with polarized UV light at a cumulative intensity of 50 mJ/ ^cm² (313 nm reference) using a polarized UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Electric Co., Ltd.).

After applying the liquid crystal curing layer composition to the obtained alignment layer using a rod coating machine, it is dried in a drying oven set to 110°C for 1 minute.

Subsequently, a high-pressure mercury lamp (UNICURE VB-15201BY-A; manufactured by Ushio Electric Co., Ltd.) was used to irradiate the film with ultraviolet light (under nitrogen atmosphere; wavelength: 365 nm; cumulative light intensity at wavelength 365 nm: 1000 mJ/cm ² ), thereby forming a liquid crystal curing layer 1 with liquid crystal compound and dichroic pigment aligned, and thus obtaining a laminated film 1 having a substrate layer, an alignment layer and a liquid crystal curing layer in sequence.

The liquid crystal curing layer 1 in the laminate 1 has a visual sensitivity correction transmittance of 42% and a visual sensitivity correction polarization of 98%.

(Fabrication of Polarizing Film) A polarizing film was obtained by irradiating the liquid crystal curing layer side of the laminate 1 with a 355 nm laser using a laser marking machine manufactured by Keyence Corporation at an output of 3.2 W, a switching frequency of 100,000 Hz, and a scanning speed of 1000 mm/s. In the obtained polarizing film, the area formed by laser irradiation is circular (10 mm in diameter), and the visual sensitivity correction transmittance is 86%. Furthermore, the appearance and hue of the area formed by laser irradiation were visually observed. The results are shown in Table 1.

[Example 2] The laser wavelength was changed to 532 nm. Otherwise, a polarizing film was fabricated in the same manner as in Example 1, and the results were observed. The results are shown in Table 1. [Example 3] The laser irradiation diameter was set to 1 mm. Otherwise, a polarizing film was fabricated in the same manner as in Example 2, and the results were observed. The results are shown in Table 1. [Example 4] The laser irradiation diameter was set to 3 mm. Otherwise, a polarizing film was fabricated in the same manner as in Example 2, and the results were observed. The results are shown in Table 1. [Example 5] The laser irradiation diameter was set to 20 mm. Otherwise, a polarizing film was fabricated in the same manner as in Example 2, and the results were observed. The results are shown in Table 1. [Example 6] A polarizing film was fabricated by irradiating the substrate layer (triacetin film) side, otherwise the same as in Example 1, and the results were observed. The results are shown in Table 1. [Example 7] A polarizing film was fabricated by irradiating the substrate layer (triacetin film) side, otherwise the same as in Example 4, and the results were observed. The results are shown in Table 1. [Comparative Example 1] A polarizing film was fabricated using the following laminated film 2, otherwise the same as in Example 2, and the results were observed. The results are shown in Table 1. (Fabrication of Laminated Film 2) A 30 μm thick polyvinyl alcohol film (average degree of polymerization approximately 2400; degree of saponification ≥ 99.9 moles) was uniaxially stretched to approximately 5 times its original thickness using a dry stretching method, and then immersed in pure water at 40°C for 40 seconds while maintaining the stretched state. Subsequently, it was immersed in a dyeing aqueous solution with an iodine/potassium iodide/water mass ratio of 0.044/5.7/100 at 28°C for 30 seconds to perform dyeing treatment. Next, it was immersed in a boric acid aqueous solution with an iodide/boric acid/water mass ratio of 11.0/6.2/100 at 70°C for 120 seconds. Next, after rinsing with pure water at 8°C for 15 seconds, the film was dried at 60°C for 50 seconds and then at 75°C for 20 seconds under a tension of 300 N, thereby obtaining a 12 μm thick liquid crystal curing layer with iodine adsorption aligned to the polyvinyl alcohol film. An aqueous adhesive was injected between the obtained liquid crystal curing layer and the triacetyl cellulose film (KC4UY-TAC manufactured by Konica Minolta; thickness 40 μm), and the layers were bonded together using rollers. While maintaining the tension of the bonded composite at 430 N/m, it was dried at 60°C for 2 minutes, thereby obtaining a laminated film 2 with a cycloene film serving as a protective film on one side. Furthermore, the aforementioned aqueous adhesive was prepared by adding 3 parts of carboxyl-modified polyvinyl alcohol (KURARAY POVAL KL318; manufactured by Kuraray Co., Ltd.) and 1.5 parts of water-soluble polyamide epoxy resin (Sumirez Resin 650; manufactured by Sumika Chemtex Co., Ltd.; an aqueous solution with a solid content of 30%) to 100 parts of water and then adjusting the mixture accordingly. [Comparative Example 2] The laser wavelength was changed to 1064 nm, and a polarizing film was prepared in the same manner as in Example 1, and the results were observed. The results are shown in Table 1. [Comparative Example 3] The laser irradiation diameter was changed to 30 mm, and a polarizing film was prepared in the same manner as in Example 2, and the results were observed. The results are shown in Table 1.

[Table 1] laminated film substrate Irradiation wavelength Irradiation diameter result [nm] [mm] Hue Appearance Implementation Example 1 Laminated film 1 Triacetyl cellulose membrane 355 10 ○ (Transparent) ○ (No wrinkles) Implementation Example 2 Laminated film 1 Triacetyl cellulose membrane 532 10 ○ (Transparent) ○ (No wrinkles) Implementation Example 3 Laminated film 1 Triacetyl cellulose membrane 532 1 ○ (Transparent) ○ (No wrinkles) Implementation Example 4 Laminated film 1 Triacetyl cellulose membrane 532 3 ○ (Transparent) ○ (No wrinkles) Implementation Example 5 Laminated film 1 Triacetyl cellulose membrane 532 20 ○ (Transparent) △(There are several wrinkles) Implementation Example 6 Laminated film 1 Triacetyl cellulose membrane 355 10 △ (Black color varies) △(There are several wrinkles) Implementation Example 7 Laminated film 1 Triacetyl cellulose membrane 532 10 ○ (Transparent) ○ (No wrinkles) Comparative example 1 Laminated film 2 Triacetyl cellulose membrane 532 10 ○ (Transparent) × (with wrinkles) Comparative example 2 Laminated film 1 Triacetyl cellulose membrane 1064 10 × (No change) ○ (No wrinkles) Comparative example 3 Laminated film 1 Triacetyl cellulose membrane 532 30 ○ (Transparent) × (with wrinkles)

In each of the polarizing films in Examples 1-7, the areas irradiated by the laser have a transparent hue. That is, each of the polarizing films in Examples 1-7 has areas with higher transparency than the areas not irradiated by the laser (i.e., areas with higher visual sensitivity correction transmittance). Therefore, it can be seen that in each of the polarizing films in Examples 1-7, the areas not irradiated by the laser correspond to Region 1, and the areas irradiated by the laser correspond to Region 2. On the other hand, in Comparative Example 2, no areas with a transparent hue were observed. Therefore, it can be seen that the polarizing film of the present invention cannot be obtained by the manufacturing method of Comparative Example 2.

1: Polarizing film 5a: Circular polarizing plate 5b: Circular polarizing plate 5c: Circular polarizing plate 11: Liquid crystal curing layer 11a: Region 1 11b: Region 2 12: Alignment layer 13: Substrate layer 15: Phase reversal layer

Figure 1(a) is a schematic top view of an example of the polarizing film of the present invention, and (b) is an X-X cross-sectional view of (a). Figures 2(a) to (c) are schematic cross-sectional views of examples of the circular polarizing plate of the present invention, respectively.

Claims (21)

A polarizing film comprising a liquid crystal curing layer, the liquid crystal curing layer containing a liquid crystal compound, and having at least a first region and a second region with different values of visual sensitivity correction transmittance, the liquid crystal compound containing a polymerizable liquid crystal compound, the second region having a higher visual sensitivity correction transmittance than the first region, and having a top-view shape that is circular, elliptical, oval, or polygonal; when the second region is circular, its diameter is 2 cm or less; when the second region is elliptical or oval, its major diameter is 2 cm or less; when the second region is polygonal, the diameter of an imaginary circle drawn inscribed in the polygon is 2 cm or less; and the difference between the thickness of the first region and the thickness of the second region is 2 μm or less. The polarizing film of claim 1 further comprises a substrate layer and an alignment layer deposited on at least one side of the substrate layer, and a liquid crystal curing layer deposited on the alignment layer. The polarizing film of claim 2, wherein the alignment layer comprises a photoaligning polymer. For any of the polarizing films requested in items 1 to 3, the visual sensitivity correction polarization value in region 1 is higher than that in region 2. For example, the polarizing film in any of requests 1 to 3, wherein the visual sensitivity correction polarization in region 1 is 90% or higher. For any of the polarizing films requested in items 1 to 3, the visual sensitivity correction polarization in region 2 is less than 10%. The polarizing film of any of claims 1 to 3, wherein the liquid crystal curing layer further contains a dichroic pigment. For example, in the polarizing film of claim 7, the content of dichroic pigment in region 1 is greater than that in region 2. For example, the polarizing film of any of requests 1 to 3, wherein the transmittance of the visual sensitivity correction element in region 1 is 35% or higher. For example, the polarizing film of any of requests 1 to 3, wherein the transmittance of the visual sensitivity correction element in region 2 is 80% or higher. For example, the polarizing film of any of requests 1 to 3, wherein region 1 shows a Boulogne peak in X-ray diffraction measurements. For example, the polarizing film in request item 2 or 3, wherein the substrate layer functions as a quarter-wavelength film. For example, the polarizing film requested in any of items 1 to 3, wherein the length of the polarizing film is 10m or more. A circular polarizer is formed by laminating a polarizing film as described in any of claims 1 to 11 and 13 and a phase détramorphic layer having a quarter-wavelength plate function. A method for manufacturing a polarizing film as claimed in claim 1, wherein the polarizing film has a lower content of dichroic pigment in a certain region of a liquid crystal curing layer than in other regions, and the manufacturing method comprises the following step: irradiating a laminated film having the liquid crystal curing layer and the substrate layer containing the dichroic pigment with a laser of a wavelength of 300 nm to 800 nm. The method for manufacturing a polarizing film, as described in claim 15, further comprises an alignment layer, wherein the laminated film has an alignment layer deposited on a liquid crystal curing layer. As in the manufacturing method of the polarizing film of claim 15 or 16, the top view shape of the region with a lower content of dichroic pigment is circular, elliptical, oval, or polygonal. When the region is circular, its diameter is 2 cm or less; when the region is elliptical or oval, its major diameter is 2 cm or less; and when the region is polygonal, the diameter of the imaginary circle drawn inscribed in the polygon is 2 cm or less. The method for manufacturing the polarizing film as described in claim 15 or 16, wherein the aforementioned liquid crystal curing layer comprises a polymer of a polymeric liquid crystal compound. For example, the manufacturing method of the polarizing film in claims 15 or 16, wherein the length of the polarizing film is 10m or more. A method for manufacturing a circular polarizer includes: step (1), which involves irradiating a laminated film comprising a liquid crystal curing layer having dichroic pigments and a substrate with a wavelength of 300 nm to 800 nm using a laser; and step (2), which involves laminating the polarizer obtained by step (1) and a phase détente layer having a 1/4 wavelength film function; wherein the polarizer is the polarizer as claimed in claim 1. For example, in the method of manufacturing the circular polarizer of claim 20, step (1) is performed after step (2).