JP2015001584A - Intrinsic polarizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intrinsic polarizer which shows enhanced absorption of light in a red light region from 600 to 640 nm, where a conventional intrinsic polarizer cannot achieve sufficient absorption of light, and which has a high polarization incident contrast in the above region, and to provide an intrinsic polarizer and an intrinsic polarizing plate which show excellent polarization performance over the whole region of visible light and give a neutral gray hue to transmitted light with polarization parallel to the transmission axis of the polarizer as well as to transmitted light with polarization perpendicular to the transmission axis.SOLUTION: The intrinsic polarizer comprises an intrinsic polarizer having such properties that when a polyvinylene structure included in oriented polymer molecules at the center in a thickness direction of an intrinsic polarizer film and on a plane parallel to the film surface is measured by Raman spectroscopy, a ratio of a Raman shift intensity derived from a vinylene (-C=C-) bond to a Raman shift intensity derived from a conjugate diene (=C-C=) bond in the polyvinylene structure is at most 1.2. The intrinsic polarizer contains a dichroic dye. A polarizing plate using the intrinsic polarizer is also provided.

Description

  The present invention relates to an intrinsic polarizer, a production method thereof, a polarizing plate using the polarizer, and a liquid crystal display device.

  A polarizing plate having a light transmission and shielding function is a basic component of a liquid crystal display (LCD) together with a liquid crystal having a light switching function. In recent years, LCDs have been applied to a wide range of applications, including personal computer displays, tablet terminals, mobile phones, projectors, in-vehicle navigation systems, liquid crystal televisions, and measuring instruments used indoors and outdoors. It is expected to be used under a wide range of conditions for both humidity and humidity. Therefore, there is a demand for a polarizing plate that has higher optical performance than conventional products and has excellent durability such as moisture and heat resistance.

  As the polarizer used for the polarizing plate, a polarizer produced by adsorbing and orienting either a dichroic dye, iodine or a dichroic dye, onto a polyvinyl alcohol-based resin film is most commonly used. Has been. Iodine-based polarizers using iodine as a dichroic dye have high transmittance and degree of polarization, and are widely used in general liquid crystal monitors, mobile phones, etc. However, there is a problem of durability such as a decrease in polarization performance. On the other hand, dye-based polarizers using dichroic dyes can be greatly improved in durability under high temperature and high humidity as compared with iodine-based polarizers, and are widely used in in-vehicle and outdoor meters. However, satisfactory durability has not yet been obtained when the projector is used under severe conditions.

Intrinsic polarizers (K-type polarizers) that do not require dichroic dyes are used in part as polarizers that are different from iodine-based polarizers and dye-based polarizers. This is a polarizer in which the polymer itself of the polymer film forming the polarizer has dichroism.
The intrinsic polarizer exhibits dichroism due to the light absorption property of a stable polyvinylene structure (or polyene fragment structure) formed in a polymer molecule constituting the film. Even if compared, it has the feature that it is remarkably excellent in moisture-and-heat resistance. Although it has been known for a long time, the manufacturing method was difficult compared to the polarizer using the above-mentioned dichroic dye, and the polarization performance was initially inferior to that of a dye-based polarizer. It was not so popular for reasons such as that. However, in recent years, improvements have been made (for example, Patent Document 1) and it has come into practical use. In particular, among intrinsic polarizers, KE polarizers with improved durability and the like have been put into practical use. For example, Patent Document 2 discloses a method for producing a PVA type intrinsic polarizer containing a vinylene polymer block. Patent Document 3 discloses an intrinsic polarizer in which the transmittance of linearly polarized light orthogonal to the transmission axis is reduced in the red light band, which improves the drawbacks of the conventional KE type polarizer.

Special table flat 10-508123 JP 2008-509433 A JP2012-088351

As the intrinsic polarizer having enhanced absorption on the long wavelength side, the above-mentioned Patent Document 3 can be cited. In Patent Document 3, the polyvinyl alcohol film is treated with a hydrochloric acid solution having a reduced hydrochloric acid concentration as a dehydration catalyst. Thus, it is disclosed that an intrinsic polarizer with enhanced absorption on the long wavelength side can be obtained. However, in the study of the present inventor, the method disclosed in Patent Document 3 is performed by the conventional method except for the hydrochloric acid concentration, so the contrast is about 10,000 at maximum. This is because, when a polyvinylene bond (also referred to as a polyene group or polyene bond) is formed, if more long polyvinylene bonds that absorb light in the red light band are generated, a large number of blocks of the long polyvinylene bonds are generated. At the same time, a number of short polyvinylene bonds and unconjugated vinylene (-C = C-) bonds are generated, and a large number of polyvinylene bonds and unconjugated vinylene bonds are generated, resulting in increased film hardness and difficulty in stretching. It is difficult to align the directionality of the polyvinylene bond, and the orientation becomes insufficient, so that the contrast is not so high. As seen from FIG. 2, the intrinsic polarizer disclosed in Patent Document 3 has an average transmittance of linearly polarized light orthogonal to the transmission axis in the red light band of 590 nm to 640 nm, as compared with the conventional intrinsic polarizer. Although it is considerably improved (hereinafter also referred to as average polarization orthogonal transmittance), the contrast is not sufficiently satisfactory.
Currently, there is a demand for clearer display in display devices, and there is a demand for intrinsic polarizers with higher contrast in the red light band.

As a result of intensive studies to solve the above-mentioned problems, the inventor is formed in a polymer in a plane parallel to the film surface (referred to as a film thickness direction central plane) in the center in the thickness direction in the intrinsic polarizing element film. Raman derived from conjugated diene (= C-C =) bond to Raman shift intensity (Raman scattering intensity) derived from vinylene (-C = C-) bond measured by laser Raman spectroscopy It has been found that the ratio of the intensity of the shift (Raman scattering intensity) (hereinafter also simply referred to as the Raman scattering intensity ratio or I ₁₁₀₈ / I ₁₄₉₃ ) greatly affects the polarization characteristics of the intrinsic polarizer. That is, according to the study of the present invention, as in Patent Document 3, in the intrinsic polarizer manufactured by the conventional method, the value of I ₁₁₀₈ / I ₁₄₉₃ is 1.22 on the central plane in the film thickness direction. It was found to show a value of about ~ 1.5.
On the other hand, the formation of polyvinylene bonds is carried out mainly in the range of 100 to 125 ° C., preferably while gradually increasing the temperature. In the intrinsic polarizer, the average polarization orthogonality in the red light region (600 nm to 640 nm) is obtained. The transmittance (hereinafter also referred to as aveTpol-c) can be reduced, and the average contrast of polarized light incidence in this region can be further increased. In this case, the film thickness direction center plane (or the film thickness direction including it) It was found that the Raman scattering intensity ratio in the middle part was lowered to 1.2 or less, and the present invention was completed.
The Raman scattering intensity ratio (or I ₁₁₀₈ / I ₁₄₉₃ ) in the present invention is a non-conjugated vinylene (-C = C) in the Raman spectrum measured by Raman spectroscopy on the central plane in the film thickness direction of the intrinsic polarizer film. -) Raman shift peak corresponding to the stretching vibration of the conjugated diene (= C-C =) bond to the intensity (I ₁₄₉₃ ) of the Raman shift peak derived from the stretching vibration of the bond (usually a peak near ₁₄₉₃ cm ^-1 ). The ratio (I ₁₁₀₈ / I ₁₄₉₃ ) of the intensity (I ₁₁₀₈ ) of the peak in the vicinity of ₁₁₀₈ cm ⁻¹ (I ₁₁₀₈ / I ₁₄₉₃ ) is an average value of values measured at a plurality of measurement points in a certain region in a plane parallel to the film surface. is there.
Further, in the intrinsic polarizer of the present invention, the absorption region of polarized light orthogonal to the transmission axis of the intrinsic polarizer moves to the long wavelength side exceeding 600 nm. Therefore, the intrinsic polarizer in the polarized light having a wavelength of 400 nm on the short wavelength side. The transmittance of polarized light orthogonal to the transmission axis is clearly higher than that of a conventional intrinsic polarizer or Patent Document 3.

The present invention relates to the following inventions.
(1) Vinylene (-C = C-) measured by Raman spectroscopy in a polyvinylene structure contained in an oriented polymer molecule in the center plane in the thickness direction of the intrinsic polarizing element film and parallel to the film surface ) An intrinsic polarizer in which the ratio of the intensity of Raman shift derived from a conjugated diene (= C—C =) bond to the intensity of Raman shift derived from a bond is 1.2 at the maximum.
(2) The intrinsic polarization according to (1) above, wherein the intrinsic polarizer has an average orthogonal transmittance of at most 0.003% in the wavelength region of 600 to 640 nm and an orthogonal transmittance at 400 nm of at least 0.3%. Child.
(3) The intrinsic polarizer according to (1) or (2) above, wherein the polarization average contrast in the wavelength region of 600 to 640 nm of the intrinsic polarizer is at least 20000.
(4) The intrinsic polarizer according to (1) or (2) above, which has a maximum absorption wavelength between 560 nm and 610 nm.
(5) The intrinsic polarizer according to any one of (1) to (4), wherein an average polarization contrast in a range of at least 40 nm before and after the maximum absorption wavelength is at least 15000.
(6) The intrinsic polarizer according to any one of (1) to (5), wherein the polyvinylene structure in the polymer molecule is formed by dehydration of a polyhydroxy linear polymer.
(7) The intrinsic polarizer according to any one of (1) to (6), further comprising a dichroic dye.
(8) The intrinsic polarizer according to (7), which is obtained by dyeing a polymer film with a dichroic dye before forming a polyvinylene structure contained in the polymer molecule.
(9) The intrinsic polarizer according to (7) or (8) above, wherein the dichroic dye is a dichroic dye having a maximum absorption wavelength in the range of 400 to 500 nm.
(10) The intrinsic polarizer according to any one of (1) to (9), which is for red light.
(11) A polarizing plate in which a protective film or a support is bonded to at least one surface of the intrinsic polarizer according to any one of (1) to (10).
(12) A display device comprising the intrinsic polarizer according to any one of (1) to (10) or the polarizing plate according to (11).
(13) The display device according to (12), wherein the display device is a projector.

According to the intrinsic polarizer of the present invention, the transmittance of polarized light orthogonal to the transmission axis of the intrinsic polarizer is remarkably increased in the red light region, which is difficult to improve with the conventional intrinsic polarizer, particularly in the wavelength region of light of 600 to 640 nm. Can be lowered. In addition, even when many long continuous polyvinylene bonds (long continuous conjugated diene bonds) that absorb light in the region are generated, short conjugated polyvinylene bonds that absorb light in the short wavelength region or unconjugated vinylene bonds. Since the number can be kept relatively low, the contrast when polarized light is incident can be significantly increased. Therefore, the intrinsic polarizer of the present invention is suitable as a red polarizer for a projector or the like.
The intrinsic polarizer of the present invention can be used as it is, or can be used as a polarizing plate in which a protective film or the like is bonded to the intrinsic polarizer, if necessary.
In addition, by using the intrinsic polarizer of the present invention for a display device, it is possible to obtain a high-contrast display device that has excellent optical performance in the red light region and does not deteriorate under long-time severe conditions. it can. In particular, by using the intrinsic polarizer of the present invention as a red light polarizer in a liquid crystal display device, the characteristics of the present invention can be fully utilized.

FIG. 1 shows a change in the value of I ₁₁₀₈ / I ₁₄₉₃ by Raman analysis in the thickness direction from the film surface of the intrinsic polarizer of the present invention and a commercially available intrinsic polarizer. The horizontal axis in FIG. 1 indicates the distance in the thickness direction from the surface of the intrinsic polarizer, and the vertical axis indicates the value of I ₁₁₀₈ / I ₁₄₉₃ .
FIG. 3 shows the transmittance of light when polarized light orthogonal to the transmission axis of each of the three intrinsic polarizers and the commercially available intrinsic polarizer is incident. The vertical axis represents the light transmittance, and the horizontal axis represents the light wavelength.
(A) of FIG. 3 shows the change with the wavelength of the single transmittance in the dye-containing intrinsic polarizer of the present invention. The horizontal axis indicates the wavelength of light, and the vertical axis indicates the light transmittance.
FIG. 3 (b) shows the change of the orthogonal transmittance according to the wavelength when the two dye-containing intrinsic polarizers of the present invention are stacked so that the transmittance is orthogonal. The horizontal axis indicates the wavelength of light, and the vertical axis indicates the light transmittance.

The intrinsic polarizer of the present invention comprises a polymer film containing an oriented polymer having a polyvinylene structure, and a plane parallel to the surface in the thickness direction of the film (perpendicular to the plane of the film surface) ( The intensity of the Raman shift derived from the conjugated diene (= C—C =) bond relative to the intensity of the Raman shift derived from the vinylene (—C═C—) bond measured by Raman spectroscopy. The ratio (the Raman scattering intensity ratio or I ₁₁₀₈ / I ₁₄₉₃ ) is 1.2 at most (in other words, 1.2 or less).
As can be seen from the above, the value of I ₁₁₀₈ / I ₁₄₉₃ is the Raman shift (usually 1493 cm ⁻¹ ) derived from the stretching vibration of the vinylene (—C═C—) bond in the Raman spectrum measured with a Raman spectrophotometer. The intensity of the Raman shift peak (usually the peak near 1108 cm ⁻¹ ) derived from the stretching vibration of the conjugated diene (= C—C =) bond relative to the intensity of the nearby peak) (hereinafter also referred to as “I ₁₄₉₃ ”). (Hereinafter also referred to as “I ₁₁₀₈ ”) (I ₁₁₀₈ / I ₁₄₉₃ ).
The Raman scattering intensity ratio (I ₁₁₀₈ / I ₁₄₉₃ ) obtained by using the Raman spectrophotometer is an average value obtained by measuring at a plurality of measurement points in a certain region in a plane parallel to the film surface. It is. The area of the region and the number of measurement points are not particularly limited. For example, in a rectangular region having a side of about 20 μm to 100 μm, the number of measurement points is about 30 to 500 per side in the vertical and horizontal directions (total number is about 900 to 25000). Any average value obtained when measurement is performed may be used.
As a technique for confirming the state of the polyvinylene structure in the polymer having the polyvinylene structure, Raman spectroscopy can be used. For Raman spectroscopy, a commercially available Raman spectrophotometer (Raman spectrometer) is used. Any material can be used as long as it can be analyzed in the thickness direction of the film. Examples thereof include NRS-5000 / 7000 series manufactured by JASCO Corporation. According to the spectrophotometer, the local Raman spectrum of the sample can be measured, and the internal structure of the sample can be analyzed in three dimensions by scanning in the surface direction and the depth direction. it can. The laser beam used for measurement is not particularly limited. For example, lasers having excitation wavelengths such as 514.5 nm and 532 nm can be used.

In Raman spectroscopy, (sometimes referred to as Raman band) Raman shift derived from the stretching vibration of vinylene "-C = C-'binding in polyvinylene structure observed as a peak in the vicinity of 1493cm ^-1 (approximately ± ^{5 cm -1)} The content is expressed as peak intensity (I ₁₄₉₃ ). Similarly, Raman shift derived from the stretching vibration of the conjugated diene "= C-C =" bonds in polyvinylene structure is observed as a peak in the vicinity of 1108cm ^-1 (approximately ± ^{5 cm -1),} the content of the peak intensity ( I ₁₁₀₈ ). As will be described in detail later, the ratio of the latter to the former (the Raman scattering intensity ratio or I ₁₁₀₈ / I ₁₄₉₃ ) is 1.2 on the central plane in the film thickness direction (the central plane in the film thickness direction) from the film surface of the intrinsic polarizer. When the following is applied, the formation of excessive polyene bonds is suppressed and the curing of the film is suppressed. As a result, the orientation of the polyvinylene structure in the stretching is sufficiently performed, resulting in a wavelength of 600 to 640 nm of the intrinsic polarizer. It is thought that the absorption of light in the region may be improved.

In the intrinsic polarizer of the present invention, the value of I ₁₁₀₈ / I ₁₄₉₃ is not particularly limited as long as it is 1.2 or less in the central plane in the film thickness direction. . In particular, it is more preferable that the value of I ₁₁₀₈ / I ₁₄₉₃ is 1.2 or less over the entire area from the film surface of the intrinsic polarizer of the present invention to the central part in the film thickness direction (central part in the film thickness direction).
A preferable value of I ₁₁₀₈ / I ₁₄₉₃ in the central plane in the film thickness direction is 1.18 or less, and more preferably 1.15 or less. More preferably, it is 1.14 or less, Most preferably, it is 1.13 or less. More preferably, the film thickness direction central plane is any one of these, and the value of I ₁₁₀₈ / I ₁₄₉₃ is 1.2 or less over the entire central portion in the film thickness direction. More preferably, it is the same as one of the values of the central plane in the film thickness direction over the entire central area in the film thickness direction.
In the present invention, the center in the film thickness direction is, for example, a portion having a thickness of 20 μm perpendicular to the thickness direction from the film surface in the case of an intrinsic polarizer having a thickness of 40 μm. Therefore, the central plane in the thickness direction parallel to the film surface (the central plane in the film thickness direction) is, for example, a portion of 20 μm perpendicular to the film surface in the thickness direction from the film surface in the case of a 40 μm thick intrinsic polarizer. It is a plane corresponding to.

In the intrinsic polarizer of the present invention, the central portion in the film thickness direction is a portion of 15% to 30% from the surface of the film and 20% to 30% from the back surface of the film with respect to the entire length of the film thickness. Excluding the portion, including the center in the film thickness direction, including before and after the film thickness, in the range of 40% to 65%, preferably in the range of 50% to 65%, most preferably 60%, relative to the total length of the film thickness. Means a range of ~ 65%.
In the intrinsic polarizer of the present invention, the lower limit of the Raman scattering intensity ratio at the film thickness direction central plane or the film thickness direction central part is not particularly limited. However, for example, considering the ease of production, the lower limit is about 0.5, and in some cases, about 0.8 or 1 is preferable.

The intrinsic polarizer of the present invention can particularly improve the polarization performance in the wavelength region of 600 to 640 nm.
The average orthogonal polarization transmittance in the wavelength region of 600 to 640 nm of the intrinsic polarizer (the average orthogonal polarization transmittance is also referred to as aveTpol-c) is 0.003% at the maximum, and preferably 0.002% or less. More preferably, it is 0.0015 or less. In addition, the said average orthogonal polarization | polarized-light transmittance means the average transmittance | permeability in the wavelength range of 600-640 nm of the transmittance | permeability when the polarized light orthogonal to the transmission axis of an intrinsic | native polarizer enters into an intrinsic | native polarizer.
Further, the preferred average parallel polarized light transmittance (average parallel polarized light transmittance is also referred to as aveTpol) in the wavelength region of 600 to 640 nm of the intrinsic polarizer of the present invention is 82% or more, preferably 83% or more, more preferably 84%. More preferably, it is 85% or more. In addition, said average parallel polarization | polarized-light transmittance means the average transmittance | permeability in the wavelength range of 600-640 nm of the transmittance | permeability when the polarization | polarized-light parallel to the transmission axis of an intrinsic polarizer enters into an intrinsic polarizer.

In the case of the intrinsic polarizer of the present invention, the average polarization incidence contrast in the wavelength region of 600 to 640 nm is preferably 20000 or more, more preferably 30000 or more, and further preferably 35000 or more. Moreover, according to the most preferable aspect of the intrinsic polarizer of the present invention, the contrast can be set to 40000 or more, 50000 or more, or 80000 or more. The average polarization incident contrast is a value obtained by dividing the average parallel polarization transmittance by the average orthogonal polarization transmittance and is a value of aveTpol / aveTpol-c.
In the intrinsic polarizer of the present invention, when polarized light orthogonal to the transmission axis of the intrinsic polarizer is incident on the intrinsic polarizer, preferably, the intrinsic absorption wavelength of the intrinsic polarizer is within a range of 560 to 610 nm. It is to be. By having the maximum absorption wavelength in this range, the polarization performance in the wavelength region of 600 to 640 nm can be particularly improved. In the intrinsic polarizer of the present invention, the average polarization incidence contrast in the range of 40 nm before and after the maximum absorption wavelength is at least 20000, preferably 30000 or more, more preferably 40000 or more, and further preferably 50000 or more. is there.

In addition, the intrinsic polarizer of the present invention has a characteristic that the light absorption region of the conventional intrinsic polarizer is moved to the longer wavelength side rather than expanding the light absorption region of the conventional intrinsic polarizer. Therefore, light absorption at a short wavelength of 400 nm decreases. Therefore, the orthogonal polarization transmittance (Tpol-c) in the light having a wavelength of 400 nm of the intrinsic polarizer is at least 0.3%, which is a higher value than the conventional intrinsic polarizer. Therefore, when increasing the absorption of the light on the short wavelength side, as will be described later, a dichroic dye that absorbs light of the wavelength in this region is inserted and oriented to increase the absorption of light in this region. It is preferable.
The optical performance of the polarizer and polarizing plate, such as transmittance and polarization degree, can be measured with a spectrophotometer (for example, V-7100 manufactured by JASCO Corporation, U-4100 manufactured by Hitachi, Ltd.). In addition, all the values measured in this specification are values measured in the state of a polarizer.

The polyvinylene structure in the polymer having an oriented polyvinylene structure in the intrinsic polarizer of the present invention can be usually formed by a dehydration reaction from a polyhydroxy linear polymer. This polyvinylene structure includes a block of polyvinylene bonds (also referred to as conjugated diene bonds) in which vinylene bonds are continuous. In general, the longer the polyvinylene bond (the more the number of continuous vinylene bonds), the longer wavelength light is absorbed. . Therefore, increasing light absorption on the long wavelength side by increasing the number of blocks of long and continuous polyvinylene bonds (for example, the number of continuous vinylene bonds is at least 14, preferably at least 15, more preferably at least 16). I can do it.
The intrinsic polarizer of the present invention can sufficiently reduce the average orthogonal polarization transmittance at 600 nm to 640 nm to 0.003% or less. Furthermore, in the intrinsic polarizer of the present invention, when the number of long and continuous polyvinylene bond blocks that absorb light in the wavelength region of 600 nm to 640 nm is increased, the light absorption on the short wavelength side (for example, 400 nm) decreases. Therefore, the number of blocks of short conjugated polyvinylene bonds (for example, the number of continuous vinylene groups is about 2 to 12) and the number of unconjugated vinylene bonds included in the intrinsic polarizer of the present invention are determined by using a conventional method. Therefore, it is considered that the absorption of light of 600 nm to 640 nm is suppressed to be lower than that of the intrinsic polarizer having the same level as that of the present invention. Therefore, it is considered that the polarization incidence contrast is remarkably improved.
When the absorption of light of 600 nm to 640 nm is increased by the conventional method, the number of short conjugated diene bonds and non-conjugated vinylene bonds increases accordingly, resulting in film curing and the orientation is not sufficiently performed Occurs.
The polyhydroxy linear polymer has a number of hydroxy groups in the molecule, and can form a polyvinylene group (also called a polyene group), particularly a conjugated diene (= C—C =) bond, by dehydration. Any polymer can be used as long as it is a polymer. The polyhydroxy linear polymer may have a substituent other than a hydroxy group as long as the effect of the intrinsic polarizer of the present invention is not lost. Examples of the substituent include a C1-C4 acyloxy group, a C1-C4 alkyl group, a phenyl group, and a carboxy group.
The ratio of substituents other than hydroxy groups is preferably in the range of 0 to 30%, more preferably about 0 to 20%, based on the total number of substituents other than hydroxy groups and hydroxy groups in the polyhydroxy linear polymer. More preferably, it is the range of about 0 to 10%.
As the polyhydroxy linear polymer, those having a polymerization degree of usually in the range of about 1000 to 10,000 are used, and a preferable degree of polymerization is about 1500 to 7000, more preferably about 2000 to 6000.

Examples of the polyhydroxy linear polymer include polyvinyl alcohol (hereinafter also referred to as PVA) or a derivative thereof, or a copolymer of polyvinyl acetate and another copolymerizable monomer (polyvinyl acetate copolymer). ) Can be preferably used. A polyvinyl alcohol polymer (hereinafter also referred to as PVA resin) obtained by saponification treatment) is preferably used. As said other copolymerizable monomer, styrene, (meth) acrylic acid or its ester (For example, ester with C1-C4 alcohol) etc. can be mentioned. In the case of a polymer obtained by saponifying the above-mentioned vinyl acetate copolymer or a polymer obtained by acylating a part of hydroxyl groups of polyvinyl alcohol with an organic acid (such as an aliphatic organic acid containing 1 to 4 carbon atoms), polyvinyl alcohol It is preferable that the component occupies 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more of the polymer constituent.
When a PVA resin film is used as a material film for an intrinsic polarizer, a film made of PVA obtained by saponifying polyvinyl acetate, which is a polymer of vinyl acetate, can be copolymerized with vinyl acetate. A film made of a PVA copolymer obtained by saponifying a copolymer (polyvinyl acetate copolymer) with another monomer, or the above PVA or PVA copolymer is converted into an olefin or an unsaturated carboxylic acid. A film made of a PVA-modified product modified with an acid (for example, (meth) acrylic acid) is preferred as the PVA-based resin.
Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids such as (meth) acrylic acid; unsaturated carboxylic acid esters such as (meth) acrylate (for example, methyl (meth) acrylate) Olefins such as ethylene, propylene and butylene; vinyl ethers; unsaturated sulfonic acids; unsaturated amines; acrylic acid derivatives such as vinyl acetate: acrylamide; and styrene.
The degree of saponification of the PVA and PVA copolymer is usually about 85 to 100 mol%, preferably 98 to 100 mol%, more preferably 99 to 100 mol%.

As a raw material film used for the intrinsic polarizer of the present invention, a film made of a PVA resin is preferable.
The PVA-based resin film is preferably a resin film in which the main component of the repeating unit in the polymer is PVA and / or a modified product thereof, and the proportion of the PVA and / or the modified product (preferably PVA) is in moles. More preferred are films of polymer in a proportion of at least 50%, preferably 70-100%, more preferably 80-100%, most preferably 90-100%.
As the PVA-based resin used in the intrinsic polarizer of the present invention, those having a polymerization degree in the range of usually about 1000 to 10,000 are used, preferably about 1500 to 7000, more preferably about 2000 to 6000. It is a range.

As a material of the intrinsic polarizer of the present invention, a film made of PVA or a PVA copolymer having the above-mentioned preferable polymerization degree and a preferable saponification degree is preferable, and a film made of PVA having the above-mentioned preferable polymerization degree and preferable saponification degree. Particularly preferred.
The thickness of the polyhydroxy linear polymer film used as the material for the intrinsic polarizer is not particularly limited, but is usually about 20 to 150 μm. The film thickness of the intrinsic polarizer of the present invention after the stretching treatment is preferably about 10 to 100 μm, more preferably about 20 to 70 μm, and still more preferably about 25 to 50 μm.

Hereinafter, the manufacturing method of the intrinsic polarizer of this invention is demonstrated.
In the production of the solid polarizer of the present invention, the time of the temperature of the film surface temperature of 125 ° C. or more and less than 130 ° C. is set to 0 to reduce the formation of polyvinylene at the film surface temperature of 125 ° C. or more as much as possible. Within 3 seconds, preferably within 0-2 seconds, more preferably within 0-1 seconds, and the film surface temperature should not exceed 130 ° C. Polyvinylene bond formation is mainly accomplished by completing the film surface temperature within 100 to 125 ° C., so that it has high absorption for polarized light having a long wavelength of 600 to 640 nm orthogonal to the transmission axis of the intrinsic polarizer. And an intrinsic polarizer exhibiting high polarization incidence contrast can be obtained. The intrinsic polarizer thus obtained has a value of I ₁₁₀₈ / I ₁₄₉₃ of 1.2 or less at the central plane in the film thickness direction.
Therefore, in order to obtain the intrinsic polarizer of the present invention, a polyhydroxy linear polymer film containing an inorganic acid as a dehydration catalyst, preferably hydrochloric acid, uniaxially stretched and oriented, is heated, preferably by infrared irradiation. It is preferable to increase the surface temperature and to carry out most of the dehydration reaction to form a polyvinylene bond at a film surface temperature of 100 ° C. to less than 130 ° C.
The film surface temperature at which the polyvinylene bond is formed is preferably in the range of 100 to 125 ° C., and the time when the film surface temperature exceeds 120 ° C. is preferably relatively short. Of the total time for maintaining the film surface temperature at a temperature of 100 ° C. to less than 130 ° C. for the formation of the polyene group, 70% to 10%, preferably 80% to 10%, more preferably 8.5%. The film surface temperature is in the range of 100 to 120 ° C., and the temperature exceeding 120 ° C. is at most about 30%, preferably 20% or less, more preferably 1.5% or less. Is preferred.

The time for forming the polyvinylene bond at a film surface temperature of 100 ° C. to less than 130 ° C. varies depending on the type and output of the heater, the type of film, the thickness, etc., and thus cannot be generally stated. Usually, the time for maintaining the film surface temperature at a temperature of 100 ° C. to less than 130 ° C. for forming the polyvinylene bond is preferably within 30 minutes at the longest. A more preferable time is about 10 minutes or less. For example, it can be as short as 3 minutes or 1 minute. The heater is not particularly limited, but an infrared heater is usually preferable.
Within the above temperature range, the film surface temperature is kept constant at a temperature higher than 100 ° C., and a polyvinylene bond is formed. Alternatively, the film surface temperature is gradually increased from 100 ° C. and less than 120 to 130 ° C. In the meantime, heating may be appropriately stopped to form a polyvinylene bond. Either method may be used, but the latter method is usually preferred.
In addition, the minimum heating time for maintaining the film surface temperature between 100 ° C. and less than 130 ° C. is the time until an appropriate polyvinylene bond is formed within the above heating time, usually 10 seconds or more. Yes, more preferably 15 seconds or more. Even in the temperature range of 100 ° C. to less than 130 ° C., if the polyene group is formed for a very long time (for example, 1 to several hours), the intrinsic polarizer of the present invention may not be obtained. .

In this invention, it can carry out according to the manufacturing method of the conventional intrinsic | native polarizer fundamentally except the temperature and time which form said polyvinylene bond.
For example, the polarizer of the present invention is a resin film containing a polyhydroxy linear polymer such as polyvinyl alcohol, preferably a polyhydroxy linear polymer film (which can contain any additive as required), (I) Acid treatment for impregnating the resin film with an acid (acid catalyst) as a dehydration catalyst, (II) Heat treatment for forming a polyvinylene bond on the resin film impregnated with the acid catalyst, (III) Polymer It is produced by subjecting a stretching treatment for orientation, preferably (IV) a curing agent treatment with boric acid or the like, and (V) a drying treatment.
The details of each step will be described below.

<Acid treatment (I)>
The acid treatment (I) is a step of impregnating the resin film with an acid as a dehydration catalyst, and the method is not particularly limited as long as the acid can be impregnated in the film. Usually, the acid treatment (I) is performed by immersing a resin film in an acid-containing solution, preferably in an acid-containing aqueous solution. In some cases, the acid treatment (I) can also be performed by applying or applying an acid-containing solution to the film, or by exposing the film to the vapor of the acid-containing solution.
As the acid used in the acid treatment (I), acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid and sulfuric acid can be preferably used, and hydrochloric acid is preferred. Examples of the solvent for the acid treatment solution include water, a water-soluble organic solvent, and a mixture thereof, and an aqueous solution is preferable.
The concentration of the solution varies depending on the type of acid used. Generally, the acid concentration in the acid aqueous solution is about 0.001% by mass to 1% by mass. For example, in the case of hydrochloric acid, it is usually 0.01 N or more, preferably 0.045 N or more, and the upper limit is not particularly limited, but is preferably 5 N or less, more preferably 1 default or less. More preferably, it is 0.045 normal -0.5 normal.
Since the immersion time varies depending on the acid concentration and the type of the film, it cannot be determined in general. Generally, it is appropriately selected between about 2 seconds and about 30 minutes.
For example, it can be performed for about 2 to 5 minutes.
The acid treatment is usually performed as the first step. Since the acid-treated film usually has an acid solution attached to the film surface, it is preferable to remove the acid solution attached to the film surface by a method such as wiping.
Further, as will be described later, in this acid treatment step, a stretching treatment may also be performed. In that case, the acid treatment and the stretching treatment can be completed by uniaxial stretching in the acid treatment solution.

<Heat treatment (II)>
This step is a step of generating a polyvinylene bond in the polyhydroxy linear polymer forming the film. This step is as described in detail above.
This step can be performed by heating the film subjected to the acid treatment (I) at a surface temperature of 100 ° C. to less than 130 ° C. for a certain time.
Through this step, the hydroxyl group of the polyhydroxy linear polymer is dehydrated to form a polyvinylene bond.
The heat treatment can be performed before the stretching treatment after the acid treatment, but it is usually preferable to perform the heat treatment on the film subjected to the acid treatment and uniaxial stretching. Usually, it is preferable to heat-treat the stretched film in an acid treatment solution. Although it is possible to heat the stretched film as it is in the acid treatment solution, it is usually preferable to carry out the treatment after removing the acid treatment solution adhering to the surface.
The “film surface temperature” in the heat treatment (II) can be measured using a known thermometer capable of measuring the film surface temperature. The thermometer to be used may be a non-contact type or a contact type. For example, a commercially available radiation thermometer or a thermometer using a thermocouple may be used.
As a heating means in the heat treatment (II), any means can be used as long as the temperature of the film can be controlled within the above range, and an infrared heater, a convection heater, or the like can be used. An infrared heater is preferably used as the heating means.

<Stretching treatment (III)>
This is a step of forming an oriented polymer in the intrinsic polarizer of the present invention.
This stretching treatment (III) can be performed either before or after the polyvinylene bond formation, or both. Usually, it is preferable to carry out both before and after the polyvinylene bond formation.
Moreover, the extending | stretching process (III) performed before polyvinylene bond formation can be performed any of before acid treatment (I), with acid treatment, or after acid treatment. Usually, the film may be stretched in an acid treatment solution together with the acid treatment (I). For example, the film is stretched after being immersed in an acid treatment solution and swollen. Further, the film may be stretched before the acid treatment (I), and the acid treatment (I) may be performed while maintaining the tension of the film. The stretching treatment (III) may be performed a plurality of times.
In a preferred embodiment of the invention, the first stretching is performed in acid treatment solution during acid treatment (I). In this first stretching, the film is stretched to a predetermined magnification, for example, about 4 to 10 times. Furthermore, it is more preferable to perform the second stretching treatment after the heat treatment (II) (after the formation of the polyvinylene bond). The second stretching is preferably 2 times or less. This second stretching can also be carried out following the curing agent treatment (V) described later. This second stretching can usually be performed in water.
The stretching treatment (III) is usually preferably uniaxial stretching.

The stretching method in the stretching treatment (III) may be either a dry stretching method or a wet stretching method, but a wet stretching method is preferred. In the wet stretching method, a solution using water, a water-soluble organic solvent or a mixed solution of water and a water-soluble organic solvent is usually heated, and the polyvinyl alcohol resin film is stretched while being immersed in the heated solution. Is done.
The temperature of the stretching solution is usually about 30 to 60 ° C. As the stretching method, a method of uniaxial stretching between two rolls having different speeds is preferable. The draw ratio of the film obtained by the stretching treatment with respect to the raw material film is about 4 to 12 times, preferably about 6 to 10 times. When the stretching process is performed a plurality of times, the total stretching ratio may be within the above range.

<Curing agent treatment (IV)>
In a preferred embodiment for producing the intrinsic polarizer of the present invention, curing agent treatment (IV) is performed. The curing agent treatment (IV) is usually performed by treating a film subjected to the acid treatment (I), the stretching treatment (III) and the heat treatment (II) with a solution containing a curing agent. As the curing agent treatment (IV), a method of immersing the above film in a solution containing a curing agent is preferable. For example, the solution may be applied to the film.

Examples of the curing agent used in the curing agent treatment (IV) include boron compounds such as boric acid or salts thereof (alkali metal salts such as borax, ammonium borax, etc.), polyvalent aldehydes such as glyoxal or glutaraldehyde, Biuret type, isocyanurate type or block type polyvalent isocyanate compounds, titanium compounds such as titanium oxysulfate, ethylene glycol glycidyl ether and polyamide epichlorohydrin can be used. Usually, boron compounds are preferred, and boric acid is more preferred. As the solvent of the curing agent treatment solution, water, a water-soluble organic solvent, a mixed solvent thereof or the like can be used, but water is preferable.
The curing agent concentration of the curing agent treatment solution varies depending on the type of the curing agent and cannot be generally specified, but is usually about 0.1 to 20% by mass, preferably about 5 to 10% by mass. The temperature of the curing agent treatment solution is preferably 80 to 100 ° C. The treatment time is usually about 30 seconds to 10 minutes, and more preferably about 1 to 5 minutes.
Moreover, the aspect which performs 2nd extending | stretching as described in the term of the extending | stretching process following this hardening | curing agent process is preferable.

In a preferred embodiment of the present invention, boric acid is contained in the resin film when the curing agent treatment is performed in an aqueous boric acid solution. The content of boric acid in the polarizer at this time is obtained by heating the obtained polarizer in pure water to completely dissolve it, adding a phenolphthalein indicator, and performing neutralization titration with an aqueous sodium hydroxide solution. Can be sought.
The boric acid content in the polarizer of the present invention is 3 to 30% by weight. The boric acid content in the polarizer can be adjusted by the concentration, immersion time, solution temperature, and stretching ratio of the solution in the stretching treatment or the curing agent treatment.

<Drying treatment (V)>
The film that has been subjected to the acid treatment (I), the stretching treatment (III), the heat treatment (II), and the curing agent treatment (IV) is washed as necessary and then subjected to a drying treatment (V). The lower limit of the drying temperature in the drying treatment (V) is about 30 ° C or higher, preferably about 40 ° C or higher, and the upper limit is about 80 ° C or lower, preferably about 70 ° C or lower. The drying time may be appropriately set depending on the drying temperature, and is usually about 1 to 20 minutes, preferably about 3 to 15 minutes. What is necessary is just to perform a drying process (V) suitably using well-known heating means, such as an infrared heater.

<Washing>
After each step of these acid treatment (I), heat treatment (II), stretching treatment (III), curing agent treatment (IV), and complementary color treatment described later, components and deposits deposited on the film surface as necessary. The film surface may be washed for the purpose of removing the foreign matter. Usually, it is preferable to wash with water, the temperature of the cleaning liquid is about 10 to 60 ° C., and the cleaning time is about 1 second to 5 minutes. Washing may be performed once or multiple times as necessary.

The intrinsic polarizer of the present invention, for example, performs the acid treatment (I) on a polyhydroxy linear polymer film (preferably a polyvinyl alcohol-based resin film) (raw film) and stretches the solution in an acid treatment solution. After the treatment (III) is performed, the heat treatment (II) is performed, the curing agent treatment (IV) and the second stretching treatment are performed, and then the drying treatment (V) is performed. can do.
The manufacturing method of the intrinsic polarizer of the present invention is not necessarily limited to the manufacturing method according to the order described above, and various modifications can be made.

The polyhydroxy linear polymer used as the material of the intrinsic polarizer of the present invention may contain one or more dichroic dyes from the viewpoint of improving optical properties. In particular, the intrinsic polarizer of the present invention containing a dichroic dye having absorption on the short-wavelength side of visible light has excellent polarization characteristics in the entire visible light region, and further includes two intrinsic polarizers of the present invention. The hue of the transmitted light when the transmission axes are arranged in parallel or orthogonal to each other can be a more preferable hue of neutral gray.
The intrinsic polarizer of the present invention containing one or two or more kinds of dichroic dyes is a process of incorporating a dichroic dye into a polyhydroxy linear polymer when the intrinsic polarizer of the present invention is produced according to the production method. (Hereinafter also referred to as complementary color processing) can be obtained. In the complementary color treatment with a dichroic dye, the resin film is immersed in a dye solution containing a dichroic dye, preferably a dye solution in which the dichroic dye is dissolved, as in the dyeing method in the method for producing a dye-based polarizer. This can be done.

  The complementary color treatment with the dichroic dye is preferably performed before any of the acid treatment (I), the heat treatment (II), the stretching treatment (III), and the curing agent treatment (IV). Thus, it is preferable to perform the complementary color treatment first because the orientation of the dichroic dye can be performed simultaneously with the orientation of the polymer of the polymer film in the stretching treatment (III) to be performed later.

  The dichroic dye is a dichroic dye used in the production of ordinary dye-based polarizers, which is a dichroic dye that is dyed on a polyhydroxy linear polymer and oriented by stretching the polymer. Any of them can be used. Preferably, a dichroic dye that absorbs blue light can be used, and it is more preferable to use a dichroic dye having a maximum absorption wavelength (λmax) of 350 to 500 nm, and dichroism having a λmax of 400 to 500 nm. More preferably, a dye is used. Preferred dichroic dyes include Yellow or Orange dichroic dyes having a λmax in the above range, such as Kayafect Yellow Y and Kayafect Orange G (both manufactured by Nippon Kayaku Co., Ltd.). The dichroic dye currently used is mentioned.

The concentration of the dichroic dye in the dyeing liquid when the film made of the polyhydroxy linear polymer is immersed in the dyeing liquid varies depending on the dyeing conditions, but cannot generally be said, but is usually about 0.5 to 20 g / L. Is more preferable, and more preferably about 2 to 10 g / L. When a plurality of dichroic dyes are used, it is preferable that the concentration of the total amount of the dyes used is in the above range.
It is preferable to use water as a solvent for the dyeing solution containing the dichroic dye. The dyeing solution containing the dichroic dye may contain an auxiliary such as a dyeing auxiliary as necessary. Examples of the dyeing aid include inorganic salts such as mirabilite and sodium tripolyphosphate. The density | concentration of the dyeing adjuvant at that time is about 0.01-10 g / L with respect to the total amount of the dyeing | staining liquid, Preferably it is about 0.05-5 g / L. When a plurality of dyeing assistants are used, the concentration of the total amount of dyeing assistants is preferably in the above range.

The temperature of the dyeing liquid in the dyeing treatment with the dichroic dye is about 20 to 60 ° C, preferably about 30 to 50 ° C. There is no problem if the dipping time is a time that can be dyed with the dyeing solution having the above concentration, and it is in the range of about 5 to 300 seconds, preferably about 10 to 200 seconds.
After the dyeing treatment, the film surface may be washed as necessary for the purpose of removing excess dyeing solution, precipitated dye and / or attached foreign matter on the film surface. Usually, it is preferable to wash with water, the temperature of the cleaning liquid is about 10 to 60 ° C., and the cleaning time is about 1 second to 5 minutes. Washing may be performed once or multiple times as necessary.

In the intrinsic polarizer of the present invention containing the dichroic dye by the complementary color treatment, the color expressed in the Lab color system of transmitted light when the two intrinsic polarizers are stacked so that the transmission axes are orthogonal to each other. The degree (a * c, b * c) is preferably −1.0 or more and 1.0 or less, more preferably −0.5 or more and 0.5 or less, and −0.3 or more. It is especially preferable that it is 0.3 or less.
The intrinsic polarizer of the present invention containing a dichroic dye by the complementary color treatment is excellent in polarization performance in the entire visible light region, and exhibits a neutral gray hue in both parallel and orthogonal positions. Since it has optical characteristics, it can be particularly preferably used as a polarizing plate used in display devices such as liquid crystal displays, plasma displays, and organic EL displays.

  The polarizing plate of the present invention is produced by forming a transparent protective layer by attaching a protective film on at least one surface of the intrinsic polarizer of the present invention obtained as described above. The protective film is added for the purpose of improving the water resistance and handling properties of the polarizer. As a raw material for the protective film, a transparent resin having excellent transparency, mechanical strength, thermal stability, moisture barrier property, etc. is particularly preferably used.

Examples of protective films include polyester resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, thermoplastic resins such as polyolefin resins and acrylic resins, and acrylic resins. And films obtained from thermosetting resins such as urethane, acrylic urethane, epoxy and silicone, or ultraviolet curable resins. Examples of the polyolefin resin include non-crystalline polyolefin resins and resins having a polymerized unit of cyclic polyolefin such as norbornene or a polycyclic norbornene monomer. Instead of laminating the protective film, a transparent protective layer may be formed by applying any of the above resins to at least one surface of the polarizer of the present invention.
A preferable protective film used for the polarizing plate of the present invention includes a film made of an acetate resin, and preferably a film made of triacetyl cellulose (TAC).

  The transparent protective film used for the transparent protective layer may be subjected to a treatment for the purpose of hard coat treatment, antireflection treatment, sticking prevention, diffusion or antiglare, etc., as long as the effects of the present invention are not impaired. good. After forming a transparent protective layer on at least one surface of the polarizer of the present invention by laminating a transparent protective film or applying a resin, these treatments may be performed. The film thickness of the transparent protective film is about 0.5 to 200 μm.

After the protective film is bonded to the polarizer of the present invention with an adhesive, the polarizing plate of the present invention can be obtained by drying or heat treatment at an appropriate temperature.
The adhesive used for the adhesive treatment between the polarizer of the present invention and the protective film is not particularly limited. For example, an adhesive made of a vinyl alcohol polymer, boric acid, borax, glutaraldehyde, melamine or the like. Adhesives composed of water-soluble crosslinking agents for vinyl alcohol polymers such as oxalic acid, highly transparent epoxy resins, polyester resins, solvent-based adhesives such as vinyl acetate, acrylic resins, urethane resins, etc. An adhesive resin or the like that can be cured by a polymerization reaction can be used. When producing the polarizing plate of the present invention, it is preferable to use a polyvinyl alcohol-based adhesive.

The polarizing plate of the present invention can also be used as an optical member by being laminated on an optical layer made of another optical material. For example, the polarizing plate of the present invention includes a reflecting plate, a transflective plate, a retardation plate (including a λ plate such as a half-wave plate and a quarter-wave plate), a viewing angle compensation film, or a brightness enhancement film. The optical member of the present invention can be produced by laminating one or two or more appropriate optical materials used for forming a liquid crystal display device or the like.
Specific examples of the optical member of the present invention include a reflective polarizing plate or a transflective polarizing plate obtained by further laminating a reflective plate or a transflective plate on the polarizing plate of the present invention; An elliptical polarizing plate or a circular polarizing plate in which a retardation plate is laminated; a polarizing plate in which a viewing angle compensation film is further laminated on the polarizing plate of the present invention; or a brightness enhancement film is further laminated on the polarizing plate of the present invention. The polarizing plate etc. which are made are mentioned.

The polarizing plate of the present invention and various optical members using the polarizing plate of the present invention can be preferably used for various devices such as a liquid crystal display device. For example, the polarizing plate of the present invention can be disposed on one side or both sides of a liquid crystal cell to produce a liquid crystal display device of a reflective type, a transmissive type, or a transmissive / reflective type. In this case, any liquid crystal cell constituting the liquid crystal display device can be used. For example, a liquid crystal cell of an appropriate type such as an active matrix driving type liquid crystal cell typified by a thin film transistor type, a simple matrix driving type liquid crystal cell typified by a twisted nematic type or a super twisted nematic type can be used.
When the polarizing plate and the optical member of the present invention are provided on both sides of the liquid crystal cell, they may be the same or different. Furthermore, when manufacturing the liquid crystal display device, for example, appropriate components such as a prism array sheet, a lens array sheet, a light diffusing plate, and a backlight can be arranged in one or more layers at appropriate positions.

  When using the polarizing plate of this invention as a member of a liquid crystal display device, the adhesion layer for adhere | attaching with other members, such as a liquid crystal cell, is normally formed in the one side or both sides of the polarizing plate of this invention. As the adhesive layer, an appropriate adhesive substance or adhesive can be used, and there is no particular limitation. Examples thereof include those using an appropriate polymer such as an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine polymer, rubber polymer as a base polymer.

  The polarizing plate of the present invention is used in all liquid crystal display devices such as twisted nematic method (TN), super twisted nematic method (STN), thin film transistor method (TFT), vertical alignment method (VA), in-plane switching method (IPS), etc. I can do it.

The intrinsic polarizer of the present invention or the polarizing plate containing the intrinsic polarizer has high durability, which is a characteristic of the intrinsic polarizer, and the conventional intrinsic polarizer has a problem in that the absorptivity of orthogonal polarization is not sufficient. In the red light region (wavelength region of 600 to 640 nm), it has the characteristics that the absorption rate of polarized light orthogonal to the transmission axis of the intrinsic polarizer is high and the contrast of polarized light incidence is large. It can be preferably used as a polarizer or polarizing plate, particularly as a polarizer or polarizing plate for a red light channel of a liquid crystal projector device.
The intrinsic polarizer of the present invention containing the dichroic dye, particularly the intrinsic polarizer or polarizing plate containing a dichroic dye having light absorption on the short wavelength side of visible light is excellent over the entire visible light range. As a polarizing plate for a display device used in the entire visible light region such as a liquid crystal display, it has a remarkably excellent optical property of exhibiting a neutral gray hue together with the above polarizing performance. Can be used.

Hereinafter, the present invention will be described more specifically with reference to examples.
The transmittance of the intrinsic polarizer in the examples was evaluated as follows.
The transmittance when using one intrinsic polarizer is the single transmittance Ys, and the transmittance when the two intrinsic polarizers are stacked so that the absorption axes are parallel is the parallel transmittance Yp and the two intrinsic polarizations. The transmittance when the children are stacked so that the absorption axes are orthogonal is defined as the orthogonal transmittance Yc. Each transmittance was calculated by the following formula (1) by obtaining a spectral transmittance τλ every predetermined wavelength interval dλ (here, 5 nm) in a certain range of wavelength region.

In the equation, Pλ represents a spectral distribution of standard light (C light source), and yλ represents a 2 ° visual field color matching function. Spectral transmittance τλ was measured using a spectrophotometer (manufactured by JASCO Corporation, product name V-7100).

Example 1
A polyvinyl alcohol resin film (polymerization degree 4000, saponification degree 98 mol% or more, thickness 75 μm) was immersed in a 0.1N hydrochloric acid aqueous solution at a liquid temperature of 40 ° C. and swollen, and then the film was added in the aqueous hydrochloric acid solution. Was uniaxially stretched 6.7 times.
Next, the obtained stretched film is taken out from the aqueous hydrochloric acid solution, wiped off the aqueous hydrochloric acid solution on the surface, and returned to room temperature with a non-contact thermocouple temperature sensor (product name μIR / c-K, manufactured by FENWAL). While monitoring the surface temperature, heating was performed using an infrared heater. Polyvinylene bonds were formed by adjusting the surface temperature of the film so that the time from 100 ° C. to less than 130 ° C. was approximately 27 seconds. The maximum temperature reached was approximately 125 ° C.
The obtained film was immersed in a 7% by weight boric acid aqueous solution having a liquid temperature of 95 ° C. to perform boric acid treatment. The dipping time was appropriately adjusted between 1 minute and 10 minutes. The boric acid-treated film was stretched by 1.04 to 1.05 times in 35 ° C. water. After removing moisture from the film surface, the film was dried for 10 minutes at 65 ° C. using an infrared heater to obtain the intended intrinsic polarizer (three types) of the present invention. The film thickness of the obtained intrinsic polarizer was approximately 40 μm.
Table 1 below shows the transmittance and contrast of the obtained intrinsic polarizer of the present invention when orthogonal or parallel polarized light is incident thereon.
Each symbol in the table has the following meaning.

Tpol-c 400 nm: Transmittance when polarized light having a wavelength of 400 nm perpendicular to the transmission axis of the intrinsic polarizer is incident
600-640 nm aveTpol-c (%): Average transmittance (%) when polarized light having a wavelength of 600-640 nm perpendicular to the transmission axis of the intrinsic polarizer is incident (600-640 nm average orthogonal polarization transmittance)
600-640 nm aveTpol (%): average transmittance (%) when polarized light having a wavelength of 600-640 nm parallel to the transmission axis of the intrinsic polarizer is incident (600-640 nm average parallel polarized light transmittance)
600-640 nm aveCRpol: (600-640 nm average parallel polarization transmittance) / (600-640 nm average orthogonal polarization transmittance)
λmax ± 40 aveTpol-c: Average transmittance between 40nm before and after λmax when polarized light perpendicular to the transmission axis of the intrinsic polarizer is incident (%)
λmax ± 40 aveTpol: Average transmittance between 40nm before and after λmax when polarized light parallel to the transmission axis of the intrinsic polarizer is incident (%)
λmax ± 40 aveCRpol: λmax when polarized light parallel to the transmission axis of the intrinsic polarizer is incident on the average transmittance (%) between 40 nm before and after λmax when the polarized light orthogonal to the transmission axis of the intrinsic polarizer is incident Ratio of average transmittance between front and rear 40nm (average polarization contrast between λmax ± 40nm)

In addition, the measurement of the transmittance | permeability in the said Table 1 and 2 was measured using the spectrophotometer (The JASCO Corporation make, product name V-7100).
As the polarized light source, a deuterium lamp, a tungsten halogen lamp, and a mercury light source were used as appropriate, and polarized light converted by a Grand Taylor prism was used.

Test Example 1 (Measurement of Raman scattering intensity ratio (I ₁₁₀₈ / I ₁₄₉₃ ))
The intrinsic polarizer of the present invention obtained in Example 1 was subjected to Raman spectroscopic analysis on a plane having a depth of 20 μm from the film surface of the polarizing film using a confocal microscopic Raman spectrophotometer under the following measurement conditions. The average value of the Raman scattering intensity ratio in the measurement region was obtained. As a result, no. 1 has a Raman scattering intensity ratio (I ₁₁₀₈ / I ₁₄₉₃ ) of a plane 20 μm deep from the film surface of the intrinsic polarizer, which is 1.120. That of the two intrinsic polarizers was 1.126.
In addition, an intrinsic polarizer (film thickness of about 40 μm) is taken out from a conventional product (commercially available product), and subjected to Raman spectroscopic analysis in the same manner as described above, and planar Raman having a depth of 20 μm from the film surface of the intrinsic polarizer. When the scattering intensity ratio (I ₁₁₀₈ / I ₁₄₉₃ ) was calculated, it was a value exceeding 1.24.

<Measurement conditions>
Measurement area (x, y): (40 μm, 40 μm)
Number of measurement points: 14400 (120 points x 120 points)
Excitation light source: Laser (λ = 532 nm)

For reference, the No. of the present invention is used. A Raman spectroscopic analysis was performed in the thickness direction straight from the film surface of 1 intrinsic polarizer toward the back surface of the film, and I ₁₁₀₈ / I ₁₄₉₃ in the thickness direction was calculated. For the conventional product, a measurement sample was prepared using the cryo-ultra microtome method, and Raman spectroscopic analysis was performed in the thickness direction, and I ₁₁₀₈ / I ₁₄₉₃ in the thickness direction was calculated. The change of I ₁₁₀₈ / I ₁₄₉₃ in both thickness directions is shown in FIG.

Example 2
Polyvinyl alcohol resin film (polymerization degree 4000, saponification degree 98 mol% or more, thickness 75 μm), orange dye (Kayafect Orange G, Nippon Kayaku Co., Ltd.) with an absorption maximum wavelength of 450 nm at a concentration of 0.9 g / L It was immersed in an aqueous solution containing 40 ° C. for 20 seconds. The excess dye solution was then washed away with water.
The obtained film was immersed in a 0.1N hydrochloric acid aqueous solution at a liquid temperature of 40 ° C. to swell, and then the film was uniaxially stretched 6.7 times in the hydrochloric acid aqueous solution.
The aqueous hydrochloric acid solution on the surface was wiped off, and the film surface was heated from room temperature using an infrared heater while monitoring the temperature of the film surface with a non-contact type thermocouple temperature sensor (manufactured by FENWAL, product name μIR / c-K). After confirming that the surface temperature of the film exceeded 120 ° C., the heating was stopped and the film surface temperature was lowered to room temperature. The time during which the surface temperature of the film was between 100 ° C. and less than 130 ° C. was approximately 27 seconds.
The obtained film was immersed in a 7% by weight boric acid aqueous solution having a liquid temperature of 95 ° C. to perform boric acid treatment. The dipping time was appropriately adjusted between 1 minute and 10 minutes. The boric acid-treated film was stretched by 1.04 to 1.05 times in 35 ° C. water. After removing moisture from the film surface, the film was dried for 10 minutes at 65 ° C. using an infrared heater to obtain the intended dye-containing intrinsic polarizer of the present invention. The film thickness of the obtained intrinsic polarizer was approximately 40 μm.

Test example 2
About the dye-containing intrinsic polarizer of the present invention obtained in Example 2 above, single transmittance and orthogonal transmittance in the following wavelength range, and transmitted light when each sample is stacked so that the transmission axes are orthogonal to each other Each of the chromaticities (a * c, b * c) expressed in the Lab color system was measured with a spectrophotometer (manufactured by JASCO Corporation, product name V-7100) under the following conditions.
Measurement wavelength: 380 to 780 nm
Calculation range: 380 to 700 nm
Measurement conditions: scan speed 600 nm / min
The measured values of single transmittance (Ys), orthogonal transmittance (Yc) and chromaticity (a * c, b * c) of each sample in the above wavelength range are shown in Table 3 below.

[Table 3]
Ys (%) Yc (%) a * c b * c
Example 2 38.9 0.0046 0.28 0.04

  The dye-containing intrinsic polarizer of the present invention obtained in Example 2 is an intrinsic polarizer obtained in the same manner as in Example 1 except that the dye-containing intrinsic polarizer was dyed with a dichroic dye, and has a wavelength of 600 to 640 nm. The absorption characteristics on the long wavelength side are remarkably improved in the same manner as in Example 1, and since an orange dye having an absorption maximum on the short wavelength side is used in combination as the dichroic dye, Excellent polarization characteristics over the wavelength range. In addition, the dye-containing intrinsic polarizer of the present invention can significantly improve the hue at orthogonal positions as compared with the conventional intrinsic polarizer.

  The intrinsic polarizer of the present invention is very useful as a polarizing plate for a red light channel of a projector because the absorption characteristics in the red light region of 600 to 640 nm, which is a problem of the conventional intrinsic polarizer, are remarkably improved. Furthermore, the intrinsic polarizer of the present invention containing a dichroic dye in a polyhydroxy linear polymer can make the hue of parallel and orthogonal transmitted light neutral grey, in addition to the above properties. Therefore, it is very useful as a polarizing plate for a display device such as a liquid crystal display.

Explanation of reference numerals in FIG. The distribution state of the value of I ₁₁₀₈ / I ₁₄₉₃ in the thickness direction of one intrinsic polarizer is shown.
2: The distribution state of the value of I ₁₁₀₈ / I ₁₄₉₃ in the thickness direction of the conventional intrinsic polarizer is shown.
Explanation of reference numerals in FIG. 3 shows the transmittance of light when polarized light orthogonal to the transmission axis of No. 3 intrinsic polarizer is incident.
2: Shows the transmittance of light when polarized light orthogonal to the transmission axis of the conventional intrinsic polarizer is incident.
Explanation of reference numerals in FIGS. The single transmittance of the dye-containing intrinsic polarizer of the present invention is shown.
2. The orthogonal transmittance when the transmission axes are orthogonalized using two dye-containing intrinsic polarizers of the present invention is shown.

Claims (13)

  Vinylene (-C = C-) bond measured by Raman spectroscopy in a polyvinylene structure contained in an oriented polymer molecule in a central plane in the thickness direction of the intrinsic polarizing element film and parallel to the film surface. The intrinsic polarizer in which the ratio of the intensity of the Raman shift derived from a conjugated diene (= C—C =) bond to the intensity of the Raman shift derived from is 1.2 at the maximum.   The intrinsic polarizer according to claim 1, wherein the intrinsic polarizer has an average orthogonal polarization transmittance of at most 0.003% in a wavelength region of 600 to 640 nm and an orthogonal polarization transmittance at 400 nm of at least 0.3%.   The intrinsic polarizer according to claim 1 or 2, wherein the intrinsic polarizer has an average polarization contrast in a wavelength region of 600 to 640 nm of at least 20,000.   The intrinsic polarizer according to claim 1, wherein the intrinsic polarizer has a maximum absorption wavelength between 560 nm and 610 nm.   The intrinsic polarizer according to any one of claims 1 to 4, wherein an average polarization contrast in a range of at least 40 nm before and after the maximum absorption wavelength is at least 20,000.   The intrinsic polarizer according to any one of claims 1 to 5, wherein the polyvinylene structure in the polymer molecule is formed by dehydration of a polyhydroxy linear polymer.   The intrinsic polarizer according to any one of claims 1 to 6, further comprising a dichroic dye.   The intrinsic polarizer according to claim 7, which is obtained by dyeing a polymer film with a dichroic dye before forming a polyvinylene structure contained in the polymer molecule.   The intrinsic polarizer according to claim 7 or 8, wherein the dichroic dye is a dichroic dye having a maximum absorption wavelength in a range of 400 to 500 nm.   The intrinsic polarizer according to any one of claims 1 to 9, which is for red light.   The polarizing plate by which the protective film or the support body was bonded to the at least single side | surface of the intrinsic | native polarizer as described in any one of Claims 1 thru | or 10.   A display device comprising the intrinsic polarizer according to any one of claims 1 to 11 or the polarizing plate according to claim 11.   The display device according to claim 11, wherein the display device is a projector.

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